<SEC-DOCUMENT>0001171843-17-001427.txt : 20170310
<SEC-HEADER>0001171843-17-001427.hdr.sgml : 20170310
<ACCEPTANCE-DATETIME>20170310170514
ACCESSION NUMBER:		0001171843-17-001427
CONFORMED SUBMISSION TYPE:	424B2
PUBLIC DOCUMENT COUNT:		3
FILED AS OF DATE:		20170310
DATE AS OF CHANGE:		20170310

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BIOCRYST PHARMACEUTICALS INC
		CENTRAL INDEX KEY:			0000882796
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				621413174
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		424B2
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	333-202466
		FILM NUMBER:		17682967

	BUSINESS ADDRESS:	
		STREET 1:		4505 EMPEROR BOULEVARD
		STREET 2:		SUITE 200
		CITY:			DURHAM
		STATE:			NC
		ZIP:			27703
		BUSINESS PHONE:		919-859-1302

	MAIL ADDRESS:	
		STREET 1:		4505 EMPEROR BOULEVARD
		STREET 2:		SUITE 200
		CITY:			DURHAM
		STATE:			NC
		ZIP:			27703
</SEC-HEADER>
<DOCUMENT>
<TYPE>424B2
<SEQUENCE>1
<FILENAME>f424b2_031017.htm
<DESCRIPTION>FORM 424B2
<TEXT>
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<P STYLE="font-size: 10pt; margin: 0pt 0 0pt 0.15in; background-color: Transparent"></P>

<P STYLE="font-size: 10pt; text-align: right; margin: 0pt 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-style: normal; text-transform: none; background-color: rgb(255, 255, 255)"><B>Filed
Pursuant to Rule 424(b)(2)</B></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><BR STYLE="box-sizing: border-box; color: rgb(54, 54, 54); font-size: 14px; font-style: normal; font-weight: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; background-color: rgb(255, 255, 255)">
<FONT STYLE="font-style: normal; text-transform: none; background-color: rgb(255, 255, 255)"><B>Registration No. 333-202466</B></FONT></FONT></P>

<P STYLE="font-size: 10pt; text-align: justify; margin: 0pt 0; color: red"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-weight: normal; font-style: normal; text-transform: none; background-color: rgb(255, 255, 255)">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-right: 0pt; margin-bottom: 0pt; background-color: transparent; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 12pt"><B>Prospectus supplement</B></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><BR>
<FONT STYLE="font-size: 12pt"><B>(To prospectus dated April 18, 2016)</B></FONT></FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-right: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 12pt"><B>&nbsp;</B></FONT></P>

<P STYLE="font-size: 18pt; margin: 0pt 0"><B><I>5,294,118 shares</I></B></P>

<P STYLE="font-size: 10pt; text-align: left; margin: 0pt 0 0pt 9.35pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; text-align: left; margin-top: 0pt; margin-right: 0pt; margin-bottom: 0pt; background-color: Transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><IMG SRC="logo.jpg" ALT=""></FONT></P>

<P STYLE="font-size: 10pt; text-align: left; margin: 0pt 0 0pt 9pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-align: left; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 12pt"><B><I>Common
stock</I></B></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">BioCryst Pharmaceuticals, Inc. is offering 5,294,118 shares of its common stock.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our common stock is listed on the NASDAQ Global Select Market under the symbol &ldquo;BCRX.&rdquo; On March
9, 2017, the last reported sale price of our common stock on the NASDAQ Global Select Market was $8.74 per share.</FONT></P>



<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>&nbsp;</B></FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" ALIGN="CENTER" STYLE="border-collapse: collapse; width: 90%">
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt; padding-bottom: 1pt; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; font-weight: bold; padding-bottom: 1pt; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: right; border-top: Black 1.5pt solid"><P STYLE="font-size: 10pt; text-align: center; margin-top: 0pt; margin-bottom: 0pt; background-color: Transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Per
                                         share</B></FONT></P></TD><TD STYLE="border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; font-weight: bold; padding-bottom: 1pt; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: right; border-top: Black 1.5pt solid"><P STYLE="font-size: 10pt; text-align: center; margin-top: 0pt; margin-bottom: 0pt; background-color: Transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Total</B></FONT></P></TD><TD STYLE="border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="width: 64%; font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Public offering price&#9;</FONT></TD><TD STYLE="width: 1%; font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 1%; font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="width: 15%; font-size: 10pt; text-align: right">8.50</TD><TD STYLE="width: 1%; font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="width: 1%; font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 1%; font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="width: 15%; font-size: 10pt; text-align: right">45,000,003</TD><TD STYLE="width: 1%; font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">Underwriting
    discounts and commissions<SUP>(1)</SUP>&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">0.51</TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">2,700,000</TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Proceeds to BioCryst,
    before expenses&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">7.99</TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">42,300,003</TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD COLSPAN="9" STYLE="font-size: 10pt; text-align: left; border-top: Black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD COLSPAN="9" STYLE="font-size: 10pt; text-align: left"><P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT>(1)
We have agreed to reimburse the underwriters for certain FINRA-related expenses. See &ldquo;Underwriting.&rdquo;</P></TD></TR>
</TABLE>




<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent">We have granted the underwriters an option for a period of 30 days to purchase up to 794,117 additional shares
of our common stock at the public offering price less the underwriting discounts and commissions.</P>



<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Investing
in our common stock involves risks. See &ldquo;Risk factors&rdquo; on page S-8 of this prospectus supplement
and in the documents incorporated by reference into this prospectus supplement and the accompanying prospectus for a discussion
of the factors you should carefully consider before deciding to purchase shares of our common stock.</B></FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>&nbsp;</B></FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Neither
the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or
passed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary
is a criminal offense.</B></FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
underwriters expect to deliver the shares on or about March&nbsp;15, 2017.</FONT></P>

<P STYLE="font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; margin: 0pt 0 0pt 9.6pt; text-align: center; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-weight: normal"><I>Sole
book-running manager</I></FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; margin: 0pt 0 0pt 9.6pt; text-align: center; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-weight: normal"><I>&nbsp;</I></FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; text-align: center; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 16pt; font-style: normal"><B>J.P.
Morgan</B></FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; text-align: center; margin: 0pt 0 0pt 9.6pt; background-color: transparent"></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><I>&nbsp;</I></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><I>Sole
lead <FONT STYLE="font-size: 10pt">manager</FONT></I></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><I>&nbsp;</I></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin-top: 0pt; margin-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 14pt"><B>Piper
Jaffray</B></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><I>&nbsp;</I></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><I>Co-<FONT STYLE="font-size: 10pt">manager</FONT></I></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><I>&nbsp;</I></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin-top: 0pt; margin-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 12pt"><B>JMP
Securities</B></FONT></P>



<P STYLE="font-size: 10pt; font-style: italic; text-align: center; margin: 0pt 0 0pt 9.6pt; background-color: transparent"><FONT STYLE="font: normal 12pt Arial, Helvetica, Sans-Serif"><B>&nbsp;</B></FONT></P>

<P STYLE="font-size: 10pt; text-align: left; margin-top: 0pt; margin-right: 0pt; margin-bottom: 0pt; background-color: Transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>March
9, 2017</B></FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 0pt 0; background-color: transparent"></P>

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OF CONTENTS</B></FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>&nbsp;</B></FONT></P>



<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="border-collapse: collapse; width: 100%">
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><B>Prospectus
    Supplement</B></FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><U>Page</U></FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">About this prospectus
    supplement</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt; text-align: right">S-<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">ii</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Forward-looking statements</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">S-iii</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="width: 83%; font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Prospectus
    supplement summary</FONT></TD><TD STYLE="width: 1%; font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 1%; font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="width: 15%; font-size: 10pt; text-align: right">S-<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">1</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
    offering</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">S-<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">7</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Risk
    factors</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">S-<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">8</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Use
    of proceeds</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">S-30</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Dilution</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">S-<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">31</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Price
    range of common stock and dividend policy</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">S-<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">33</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Underwriting</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">S-<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">34</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Legal
    matters</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">S-<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">39</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Experts</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">S-<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">39</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Where
    you can find more information</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">S-<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">40</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left; text-indent: -0.25in; padding-left: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Incorporation
    of certain documents by reference</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right">S-40</TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; font-weight: bold"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; font-weight: bold"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; font-weight: bold; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; font-weight: bold; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; font-weight: bold"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Prospectus</FONT></TD><TD STYLE="font-size: 10pt; font-weight: bold"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; font-weight: bold; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><U>Page</U></FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">About this Prospectus</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">i</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Prospectus Summary</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">1</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Risk Factors</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">2</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Information Regarding
    Forward-Looking Statements</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">3</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Use of Proceeds</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">5</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Description of Common
    Stock, Preferred Stock and Depositary Shares</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">6</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Description of Stock
    Purchase Contracts</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">9</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Description of Warrants</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">10</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Description of Units</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">12</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Plan of Distribution</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">13</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Legal Matters</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">16</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Experts</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">16</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Where You Can Find More
    Information</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">17</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Incorporation of Certain
    Documents by Reference</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">17</FONT></TD></TR>
</TABLE>



<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>



<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 16pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; text-transform: none"><B>About
this prospectus supplement</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">This
document is part of a registration statement that we filed with the Securities and Exchange Commission (the &ldquo;SEC&rdquo;)
using a &quot;shelf&quot; registration process and consists of two parts. The first part is the prospectus supplement, which describes
the specific terms of this offering of shares of our common stock and also adds to and updates information contained in the accompanying
prospectus and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus. The second
part is the accompanying prospectus, or the base prospectus, dated April 18, 2016, including the documents incorporated by reference
therein, which provides more general information, some of which may not apply to this offering. Generally, when we refer to this
prospectus, we are referring to both parts of this document combined. You should read both this prospectus supplement and the
accompanying prospectus, together with the additional information described under the caption &ldquo;Where you can find more information&rdquo;
below.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">Neither
we nor the underwriters have authorized anyone to provide you with information different from that contained
in or incorporated by reference into this prospectus supplement, the accompanying prospectus or any free writing prospectus prepared
by us or on our behalf. We and the underwriters take no responsibility for, and can provide no assurances as to the reliability
of, any information other than the information contained in or incorporated by reference into this prospectus supplement, the accompanying
prospectus or any free writing prospectus prepared by us or on our behalf. Neither we nor the underwriters are offering to sell,
nor seeking offers to buy, shares of our common stock in any jurisdiction where an offer or sale is prohibited. You should assume
that the information appearing in or incorporated by reference into this prospectus supplement, the accompanying prospectus or
any free writing prospectus prepared by us or on our behalf is accurate or complete only as of their respective dates or on the
date or dates which are specified in such documents, and that any information in documents that we have incorporated by reference
is accurate or complete only as of the date of such document incorporated by reference. Our business, financial condition, liquidity,
results of operations and prospects may have changed since those dates. Management estimates are derived from publicly available
information, our knowledge of our industry and assumptions based on such information and knowledge, which we believe to be reasonable.
In addition, assumptions and estimates of our and our industry's future performance are necessarily subject to a high degree of
uncertainty and risk due to a variety of factors, including those described in &quot;Risk factors&quot; in this prospectus supplement,
the accompanying prospectus and in our Annual Report on Form 10-K for the fiscal year ended December 31, 2016, which is incorporated
by reference into this prospectus supplement. These and other important factors could cause our future performance to differ materially
from our assumptions and estimates. See &quot;Forward-looking statements.&quot;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If
the information set forth in this prospectus supplement, on the one hand, differs in any way from the information set forth in
the accompanying prospectus or in a document which is incorporated by reference herein or therein that was filed with the SEC
before the date of this prospectus supplement, on the other hand, you should rely on the information set forth in this prospectus
supplement. If any statement in one of these documents conflicts with a statement in another document having a later date (for
example, a document incorporated by reference in this prospectus supplement or in the accompanying prospectus), the statement
in the document having the later date modifies or supersedes the earlier statement.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Unless
otherwise mentioned or unless the context requires otherwise, all references in this prospectus supplement and the accompanying
prospectus to &ldquo;BioCryst,&rdquo; the &ldquo;Company,&rdquo; &ldquo;we,&rdquo; &ldquo;us&rdquo; and &ldquo;our&rdquo; refer
to BioCryst Pharmaceuticals, Inc. together with its consolidated subsidiaries.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 16pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; text-transform: none"><B>Forward-looking
statements</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">This
prospectus supplement and the accompanying prospectus, including the information we incorporate by reference, contain forward-looking
statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the &ldquo;Securities Act&rdquo;) and
Section 21E of the Securities Exchange Act of 1934, as amended (the &ldquo;Exchange Act&rdquo;), which are subject to the &ldquo;safe
harbor&rdquo; created in Section 21E. All statements other than statements of historical facts contained in this prospectus supplement,
the accompanying prospectus and the information we incorporate herein and therein by reference are forward-looking statements.
These forward-looking statements can generally be identified by the use of words such as &ldquo;may,&rdquo; &ldquo;will,&rdquo;
&ldquo;intends,&rdquo; &ldquo;plans,&rdquo; &ldquo;believes,&rdquo; &ldquo;anticipates,&rdquo; &ldquo;expects,&rdquo; &ldquo;estimates,&rdquo;
&ldquo;predicts,&rdquo; &ldquo;potential,&rdquo; the negative of these words or similar expressions. Statements that describe
our future plans, strategies, intentions, expectations, objectives, goals or prospects are also forward-looking statements. These
forward-looking statements include, but are not limited to, statements about:</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         preclinical development, clinical development, commercialization, or post-marketing studies
                                         of our product candidates and products,&nbsp;including our hereditary angioedema (&ldquo;HAE&rdquo;)
                                         program, peramivir, galidesivir, and early stage discovery programs;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         potential funding from our contracts with the Biomedical Advanced Research and Development
                                         Authority (the &ldquo;BARDA/HHS&rdquo;) and the National Institute of Allergy and Infectious
                                         Diseases (&ldquo;NIAID/HHS&rdquo;) for the development of galidesivir;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         potential for government stockpiling orders of peramivir, additional regulatory approvals
                                         of peramivir, or milestones, royalties or profit from sales of peramivir by us or our
                                         partners;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         potential use of peramivir as a treatment for H1N1, H5N1, and H7N9 or other strains of
                                         influenza;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         implementation of our business model, strategic plans for our business, products, product
                                         candidates and technology;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to establish and maintain collaborations or out-license rights to our product
                                         candidates;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">plans,
                                         programs, progress and potential success of our collaborations, including Seqirus UK
                                         Limited (&ldquo;SUL&rdquo;) for peramivir, Mundipharma International Holdings Limited
                                         (&ldquo;Mundipharma&rdquo;) for forodesine, and Shionogi &amp; Co., Ltd. (&ldquo;Shionogi&rdquo;)
                                         and Green Cross Corporation (&ldquo;Green Cross&rdquo;) for peramivir in their territories;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         ability of our wholly-owned subsidiary, JPR Royalty Sub LLC (&ldquo;Royalty Sub&rdquo;),
                                         to service its payment obligations in respect of its PhaRMA Senior Secured 14.0% Notes
                                         due 2020 (the &ldquo;PhaRMA Notes&rdquo;), and our ability to benefit from our equity
                                         interest in Royalty Sub;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         foreign currency hedge agreement entered into by us in connection with the issuance by
                                         Royalty Sub of the PhaRMA Notes;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         scope of protection we are able to establish and maintain for intellectual property rights
                                         covering our product candidates and technology;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to operate our business without infringing the intellectual property rights of
                                         others;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">estimates
                                         of our expenses, revenues, capital requirements, annual cash utilization, and our needs
                                         for additional financing;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to continue as a going concern;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         timing or likelihood of regulatory filings or regulatory agreements, deferrals and approvals;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to raise additional capital to fund our operations or repay our recourse debt
                                         obligations;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

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<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to comply with the covenants as set forth in the agreements governing our debt
                                         obligations;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         financial performance; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">competitive
                                         companies, technologies and our industry.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">These
statements relate to future events or to our future financial performance and involve known and unknown risks, uncertainties and
other important factors that may cause our actual results, performance or achievements to be materially different from any future
results, performance or achievements expressed or implied by these forward-looking statements. Factors that may cause actual results
to differ materially from current expectations include, among other things, those listed under &ldquo;Risk factors&rdquo; and
elsewhere in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein.
Any forward-looking statement reflects our current views with respect to future events and is subject to these and other risks,
uncertainties and assumptions relating to our operations, results of operations, industry and future growth. Except as required
by law, we assume no obligation to update or revise these forward-looking statements for any reason, even if new information becomes
available in the future.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Discussions
containing these forward-looking statements are also included in &ldquo;Management&rsquo;s Discussion and Analysis of Financial
Condition and Results of Operations&rdquo; incorporated by reference from our most recent Annual Report on Form 10-K, our Current
Reports on Form 8-K, as well as any amendments we make to those filings with the SEC.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt; text-transform: none"><B>&nbsp;</B></FONT></P>

<TABLE BORDER="0" CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; border-collapse: collapse; font-size: 10pt">
<TR STYLE="vertical-align: bottom">
    <TD STYLE="width: 2%; border-top: Black 1.1pt solid; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 96%; border-top: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 2%; border-top: Black 1.1pt solid; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 12pt; font-weight: bold; vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 16pt; text-transform: none">Prospectus
    supplement summary</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 12pt; font-weight: bold; vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">This summary highlights information contained elsewhere or incorporated by reference in this prospectus supplement,
the accompanying prospectus or any free writing prospectus prepared by us or on our behalf and does not contain all of the information
that you should consider before investing in shares of our common stock. You should read this entire prospectus supplement and
the accompanying prospectus carefully, including the &ldquo;Risk factors&rdquo; section of this prospectus supplement beginning
on page S-8 and the consolidated financial statements and related notes and other information incorporated by reference in this
prospectus supplement and the accompanying prospectus, before making an investment decision.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 12pt; font-weight: bold; vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 14pt">BioCryst
    Pharmaceuticals, Inc.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 12pt; font-weight: bold; vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We are a biotechnology company
    that designs, optimizes and develops novel small molecule drugs that block key enzymes involved in the pathogenesis of diseases.
    We focus on the treatment of rare diseases in which significant unmet medical needs exist and that align with our capabilities
    and expertise. We integrate the disciplines of biology, crystallography, medicinal chemistry and computer modeling to discover
    and develop small molecule pharmaceuticals through the process known as structure-guided drug design.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-weight: bold; font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Drugs
    and drug candidates</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-weight: bold; font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Set forth below is a description
    of our main drugs and drug candidates in development.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-weight: bold; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Rare disease
    programs</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-weight: bold; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><U>Hereditary
    Angioedema (&ldquo;HAE&rdquo;) Drug Candidates:</U></FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle; padding-left: 30pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">2nd
    generation HAE compounds&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The goal of our second generation
    HAE discovery program is to discover and develop oral molecules for the prevention of HAE attacks which have a superior selectivity
    and bioavailability profile while maintaining similar potency as compared to avoralstat, our first oral drug candidate to
    treat HAE. HAE is a rare, severely debilitating and potentially fatal genetic condition that occurs in approximately 1 in
    50,000 people. HAE symptoms include recurrent episodes of edema in various locations, including the hands, feet, face, genitalia
    and airway. Airway swelling is particularly dangerous and can lead to death by asphyxiation. In addition, patients often have
    bouts of excruciating abdominal pain, nausea and vomiting caused by swelling in the intestinal wall.&nbsp;By inhibiting plasma
    kallikrein, our HAE drug candidates suppress bradykinin production. Bradykinin is the mediator of acute swelling attacks in
    HAE patients.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In December 2013, we announced
    the selection of two optimized plasma kallikrein inhibitors to advance into preclinical development as potential once-daily,
    oral prophylactic treatments for HAE. Based on early preclinical development studies, these structurally different molecules
    have a similar mechanism of action as avoralstat and have achieved the principal goal of improved bioavailability. Both BCX7353
    and the other compound had roughly five times better bioavailability than avoralstat. These compounds demonstrated sub-nanomolar
    potency on the isolated enzyme and single digit nanomolar potency in suppressing kallikrein activity in an ex-vivo activated
    normal human plasma kallikrein inhibition (&ldquo;aPKI&rdquo;) assay. Plasma concentrations of each of the optimized compounds
    exceeded the aPKI assay EC80 concentration at 24 hours after a single oral dose of 10 mg/kg in rats, indicating potential
    for once-daily dosing. In January 2015, we selected BCX7353 to advance into Phase 1 development to evaluate its potential
    as a once-daily, oral prophylactic HAE treatment. In addition to BCX7353, we continue to work on and advance other second
    generation compounds. These molecules are in preclinical development and are being assessed for safety and efficacy in prophylactic
    HAE treatment as well as for other potential indications. We will provide additional information on these molecules as we
    approach an Investigational New Drug filing or we obtain data suggesting efficacy and safety surrounding these molecules in
    HAE and other therapeutic indications.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle; padding-left: 30pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">BCX7353</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">BCX7353 is structurally different
    from and is expected to have superior efficacy as compared to avoralstat, but has a similar mechanism of action targeting
    plasma kallikrein. On May 13, 2015, we announced the initiation of a Phase 1 clinical trial to evaluate the safety, pharmacokinetics
    and pharmacodynamics of orally-administered BCX7353 in healthy volunteers.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid; border-bottom: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle; border-bottom: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid; border-bottom: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
</TABLE>


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<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt; text-transform: none"><B>&nbsp;</B></FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; font-style: italic; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-weight: normal; font-style: normal">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-weight: normal; font-style: normal">&nbsp;</FONT></P>

<TABLE BORDER="0" CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; border-collapse: collapse; font-size: 10pt">
<TR STYLE="vertical-align: bottom">
    <TD STYLE="width: 2%; border-top: Black 1.1pt solid; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 96%; border-top: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 2%; border-top: Black 1.1pt solid; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In December 2015, we successfully
    completed a Phase 1 clinical trial of BCX7353 in Western and Japanese healthy volunteers. In the Western portion of this trial,
    we studied BCX7353 single doses of up to 1000mg, once-daily doses of up to 500mg for seven days, and once-daily doses of 350mg
    for 14 days in healthy Western volunteers. Plasma levels increased in approximate proportion to dose, and drug exposure was
    not affected by dosing with food. The half-life of BCX7353 was estimated at 67-79 hours. After daily dosing, blood levels
    met or exceeded a predicted target therapeutic range of 4 to 8 times the 50% effective concentration (&ldquo;EC50&rdquo;)
    for plasma kallikrein inhibition throughout the 24 hour dosing interval. Inhibition of the target enzyme, plasma kallikrein,
    was measured in a sensitive and specific bioassay. Daily dosing with BCX7353 strongly inhibited plasma kallikrein at all four
    dose levels; the degree of inhibition was dose-related (p &lt; 0.0001) and inhibition was sustained throughout the 24 hour
    dosing interval. This pharmacodynamic effect correlated strongly to the achieved drug concentration (r = 0.91, p &lt; 0.0001).</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In the Japanese portion of this
    trial, we enrolled cohorts of healthy Japanese volunteers and gave single oral doses of BCX7353 of 100mg and 500mg, and daily
    doses of 250mg of BCX7353 for seven days. Compared to Western subjects administered the same dose level, plasma drug levels
    in Japanese subjects were moderately higher. Kallikrein inhibition on day seven of daily dosing with 250mg in Japanese subjects
    was similar to that seen at the 350mg daily and 500mg daily dose levels in Western subjects.&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The combined data from all Phase
    1 clinical trials completed as of July 2016 indicates that oral BCX7353 has been generally safe and well tolerated in a total
    of 117 healthy volunteers, 46 receiving single doses of up to 1000 mg, and 71 receiving once-daily doses of up to 500 mg for
    7 days and 350 mg for 14 days. In our Phase 1 trials, we have observed an approximate 5% rate of drug-related rash in healthy
    volunteers administered daily doses of BCX7353 for at least 7 days. This drug-related rash has appeared within the first 14
    days of drug administration and has resolved within a few days after discontinuing the drug. No serious adverse events have
    been seen and no dose-limiting toxicity has been identified. There have been no clinically significant laboratory abnormalities,
    ECG changes, or vital sign changes observed.&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The safety, tolerability, drug
    exposure and on-target plasma kallikrein inhibition results strongly supported advancing the development program into a Phase
    2 study in HAE patients. In August 2016, we commenced a Phase 2 trial (&ldquo;APeX-1&rdquo;) to evaluate the safety, tolerability,
    pharmacokinetics, pharmacodynamics and efficacy of BCX7353 as a preventative treatment to reduce the frequency of attacks
    in HAE patients.&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle; padding-left: 30pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">APeX-1 Trial</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In August 2016, we announced that
    we had dosed the first subject in the APeX-1 clinical trial of BCX7353 for the oral treatment of HAE. APeX-1 is a multi-part,
    Phase 2, randomized, double-blind, placebo-controlled, dose ranging trial to evaluate the safety, tolerability, pharmacokinetics,
    pharmacodynamics and efficacy of BCX7353 as a preventative treatment to eliminate or reduce the frequency of angioedema attacks
    in HAE patients. APEX-1 is being conducted in several European countries, Australia and Canada. In part 1 of APeX-1, subjects
    with HAE were randomized in a 1:1 ratio to receive an oral dose of either 350 mg of BCX7353 once daily (&ldquo;QD&rdquo;)
    or placebo QD for 28 days. The primary efficacy endpoints of APeX-1 are the number of angioedema attacks; attack rate per
    week, counts of attacks, proportion of subjects with no attacks, and number of attack-free days. Efficacy analyses will be
    conducted for HAE attacks reported over the entire dosing interval (Days 1 through 28) and during the dosing period in which
    plasma concentrations of BCX7353 should be at steady-state conditions (Days 8 through 28). Secondary efficacy endpoints include
    severity and duration of angioedema attacks and measures of health-related quality of life. Safety will be characterized through
    evaluation of adverse events and laboratory testing. Pharmacokinetics and pharmacodynamic effects will be assessed through
    measurement of plasma drug levels and kallikrein inhibition. A total of approximately 36 subjects have been enrolled in part
    1.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">On February 27,
    2017, we reported statistically significant and clinically meaningful reductions in attack frequency from an interim analysis
    of part 1 of our ongoing multi-part APeX-1 clinical trial in HAE patients. In the interim analysis, twenty-eight subjects
    were randomized equally to receive BCX7353 350 mg QD or placebo for 28 days. The baseline attack rate was approximately 1/week
    and average C1 inhibitor levels were less than 20% of the normal mean, indicating a severely affected patient population.
    Baseline characteristics of trial participants were generally well balanced between the two groups with the exception of prior
    androgen use, which was more common in the BCX7353 group (11 of 14 compared with 6 of 14 on placebo). Compliance with study
    drug dosing in the interim analysis of part 1 of the trial was greater than 98%.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid; border-bottom: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle; border-bottom: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid; border-bottom: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
</TABLE>


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<P STYLE="font-size: 10pt; font-style: italic; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-weight: normal; font-style: normal">&nbsp;</FONT></P>

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<TABLE BORDER="0" CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; border-collapse: collapse; font-size: 10pt">
<TR STYLE="vertical-align: bottom">
    <TD STYLE="width: 2%; border-left: Black 1.1pt solid; border-top: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 96%; border-top: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 2%; border-right: Black 1.1pt solid; border-top: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The pre-specified per-protocol
    (&ldquo;PP&rdquo;) interim analysis included data on 24 subjects with confirmed Type 1 or Type 2 HAE and completing 28 days
    of treatment (11 on BCX7353 and 13 on placebo). The mean rate of independently-adjudicated angioedema attacks for the pre-defined
    effective dosing period (weeks 2 through 4) in BCX7353-treated subjects was 0.34/week compared to 0.92/week for placebo, a
    reduction of 0.57/week (63%), p = 0.006. In the intent-to-treat (&ldquo;ITT&rdquo;) population of 28 subjects, the rate of
    attack for the effective dosing period for BCX7353 and placebo groups was 0.44/week and 0.91/week, a reduction of 0.47/week
    (52%), p = 0.035.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">A pre-planned analysis of peripheral
    and abdominal attacks showed reductions of 88% and 24%, respectively, for BCX7353 compared with placebo (PP analysis, weeks
    2 through 4). To understand this difference, patient diaries were reviewed and abdominal attacks (n = 9, BCX7353 and n = 14,
    placebo) were subdivided into two groups: attacks with abdominal symptoms only and attacks with a combination of abdominal
    and peripheral symptoms (mixed attacks). This post-hoc analysis showed that there were 2, 2 and 7 peripheral, mixed and abdominal-only
    attacks on BCX7353 compared with 22, 12 and 2 attacks, respectively, for placebo. Based on this distribution, it is likely
    that subjects recorded abdominal adverse events as HAE attack symptoms in their diary. Accordingly, this post-hoc analysis
    indicated an 88% reduction in the number of attacks for subjects treated with BCX7353, as compared to the placebo arm, characterized
    by either peripheral symptoms-only or a combination of peripheral and abdominal symptoms.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Pharmacokinetic and pharmacodynamic
    analyses indicate steady state BCX7353 plasma levels in HAE subjects were similar to those in healthy subjects administered
    the same dose in a previously completed Phase 1 trial. Steady state trough drug levels (24 hours after dosing) were 11 &ndash;
    32 times EC50 for plasma kallikrein inhibition. These observed steady state drug levels greatly exceeded our proposed therapeutic
    target range of 4 &ndash; 8 times the EC50. Daily oral dosing with BCX7353 strongly inhibited plasma kallikrein throughout
    the 24-hour dosing interval and the degree of inhibition was similar to that seen with this dose in the healthy subject Phase
    1 trial.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Oral BCX7353 350 mg QD for 28 days
    was generally safe and well tolerated in subjects with HAE. There were no serious adverse events (&ldquo;AEs&rdquo;) and no
    related severe AEs. Two subjects in the BCX7353 treatment group discontinued study drug before day 28, one due to an unrelated
    pre-existing liver disorder, and one due to an adverse event of gastroenteritis associated with elevated liver enzymes. Treatment-emergent
    adverse events occurring in at least two subjects overall, enumerated by treatment group (BCX7353 [n=14] and placebo [n=14]),
    respectfully, were: common cold (3, 4); diarrhea (4, 2); flatulence (2, 0); and fatigue (2, 0). No clinically significant
    changes in hematology parameters, renal function tests, electrolytes, or urinalysis were observed. One subject treated with
    BCX7353, with pre-existing colitis, hepatic steatosis (i.e., a fatty liver) and more than 20 years of prior androgen use,
    had an elevation of alanine aminotransferase &gt; 3 times the upper limit of normal at the end of treatment, which resolved.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Based upon this interim analysis,
    the efficacy, safety and tolerability profile of BCX7353 observed strongly supports its continued development as a prophylactic
    treatment for HAE. Furthermore, the steady state drug levels observed greatly exceeded our proposed therapeutic target range
    of 4 &ndash; 8 times the EC50, thereby supporting and prompting us to evaluate doses of BCX7353 lower than the 350 QD tested
    in part 1 of the trial. Therefore, the APeX-1 trial has been amended to add a 62.5 mg QD dose level, and to increase the number
    of subjects at the 125 mg QD and 250 mg QD dose levels, in order to more fully characterize dose response. Specifically, part
    2 of APeX-1 will enroll 14 additional subjects with HAE and they will be randomized to 250mg of BCX7353 QD (n=6), 125mg of
    BCX7353 QD (n=6) or placebo (n=2) and part 3 of APeX-1 will enroll 20 additional subjects with HAE and they will be randomized
    to 250mg of BCX7353QD (n=6), 125mg of BCX7353 QD (n=6), 62.5mg of BCX7353 QD (n=6) or placebo (n=2).</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">On October 27, 2015 The Japanese
    Ministry of Health Labor &amp; Welfare (&ldquo;MHLW&rdquo;) announced that BioCryst&rsquo;s BCX7353 was one of six products
    designated under MLHW&rsquo;s new Sakigake fast track review system. The Sakigake Designation System promotes R&amp;D in Japan,
    aiming at early market availability for innovative pharmaceutical products. This designation provides for additional interactions
    with the regulatory agency in Japan from early development through filing, prioritized development and review, and introduction
    of the product as soon as possible to address a serious unmet medical need. We expect the results of APeX-1 to help us and
    the MHLW determine the regulatory pathway and timeline for BCX7353 in Japan.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-bottom: Black 1.1pt solid; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle; border-bottom: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-bottom: Black 1.1pt solid; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
</TABLE>


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<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<TABLE BORDER="0" CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; border-collapse: collapse; font-size: 10pt">
<TR STYLE="vertical-align: bottom">
    <TD STYLE="width: 2%; border-top: Black 1.1pt solid; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 96%; border-top: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 2%; border-top: Black 1.1pt solid; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-weight: bold; font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Infectious
    disease programs</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-weight: bold; font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><U>Peramivir
    injection (RAPIVAB<FONT STYLE="font-size: 10pt; font-weight: normal"><I><SUP>&reg;</SUP>, RAPIACTA<SUP>&reg;</SUP>, PERAMIFLU<SUP>&reg;</SUP>,
    ALPIVAB<SUP>TM</SUP>)</I></FONT></U></FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Peramivir is an intravenous neuraminidase
    inhibitor approved in multiple countries for the treatment of patients with influenza. Influenza is a seasonal virus with
    the highest infection rates generally observed in colder months. In countries for which peramivir is commercially available,
    influenza occurs primarily during the September to April timeframe. Peramivir is available commercially in the United States
    and has been approved for commercial use in Canada under the name RAPIVAB<FONT STYLE="font-size: 10pt; font-weight: normal; font-style: normal"><SUP>&reg;</SUP>,
    in Japan and Taiwan as RAPIACTA<SUP>&reg;</SUP>, and in Korea as PERAMIFLU<SUP>&reg;</SUP>.&nbsp;&nbsp;</FONT></FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Peramivir was most recently approved
    in Canada in January 2017, and was approved in the United States in December 2014, in each case for the treatment of acute
    uncomplicated influenza in patients 18 years and older who have been symptomatic for no more than two days. Data from over
    2,700 subjects treated with peramivir in 27 clinical trials was utilized to support regulatory approval in these countries.
    We made RAPIVAB available for commercial sale in the U.S. through agreements with specialty distributorships during the 2014-2015
    influenza season. On June 17, 2015, we announced that we licensed RAPIVAB (peramivir injection) for the treatment of influenza
    to CSL Limited (&ldquo;CSL&ldquo;), a global biopharmaceutical company. RAPIVAB is being commercialized by a subsidiary of
    CSL called Seqirus UK Limited (&ldquo;SUL&rdquo; or &ldquo;Seqirus&rdquo;), which specializes in influenza prevention through
    the supply of seasonal and pandemic influenza vaccine to global markets. Under the terms of the agreement, SUL obtained worldwide
    rights to commercialize RAPIVAB, with the exception of Japan, Korea, Taiwan and Israel. BioCryst retained all rights to pursue
    pandemic stockpiling orders for RAPIVAB from the U.S. Government, while SUL is responsible for government stockpiling outside
    the U.S. With the out-license of RAPIVAB to SUL, and our recent Canadian regulatory approval, our current goals for RAPIVAB
    are to: (1) obtain a stockpiling procurement contract with the U.S. Government; (2) fulfill our post-approval development
    requirements, including conducting a pediatric trial in the United States and submitting a supplemental New Drug Application
    (&ldquo;sNDA&rdquo;) for a pediatric indication; and (3) receiving regulatory approval for our Marketing Authorization Application
    (&ldquo;MAA&rdquo;) in the European Union.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In January 2017, we announced that
    the European Medicines Agency (&ldquo;EMA&rdquo;) has accepted the filing of our peramivir injection MAA for treatment of
    symptoms typical of influenza in adults 18 years and older. If the MAA is approved, Seqirus will commercialize peramivir as
    ALPIVAB<FONT STYLE="font-size: 10pt; font-weight: normal; font-style: normal"><SUP>TM</SUP> in the European Union. The acceptance
    of the MAA begins the review process by the EMA under the centralized licensing procedure for all 28 member states of the
    European Union, Norway and Iceland.&nbsp;</FONT></FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">RAPIVAB was developed under a $234.8
    million contract from the Biomedical Advanced Research and Development Authority within the United States Department of Health
    and Human Services (&ldquo;BARDA/HHS&rdquo;), which expired on June 30, 2014.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In January 2010, our partner Shionogi
    &amp; Co., Ltd. (&ldquo;Shionogi&rdquo;) received the first approval for peramivir injection and launched it in Japan under
    the commercial name RAPIACTA. It is approved for the treatment of adults, children and infants with uncomplicated seasonal
    influenza and those patients at high-risk for complications associated with influenza. In August 2010, Green Cross Corporation
    (&ldquo;Green Cross&rdquo;) received marketing and manufacturing approval from the Korean Food &amp; Drug Administration under
    the commercial name PERAMIFLU to treat patients with influenza A &amp; B viruses, including pandemic H1N1 and avian influenza.
    In addition, we have a regional collaboration for the development and commercialization of peramivir in Israel.&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><U>Galidesivir
    (formerly BCX4430) broad spectrum anti-viral</U></FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Galidesivir is a broad-spectrum
    antiviral (&ldquo;BSAV&rdquo;) research program and is currently being developed under contracts with the National Institute
    of Allergy and Infectious Diseases (&ldquo;NIAID/HHS&rdquo;) and BARDA/HHS. The objective of our BSAV program is to develop
    galidesivir as a broad-spectrum therapeutic for viruses that pose a threat to national health and security. The primary focus
    of the program is treatment of hemorrhagic fever viruses. NIAID/HHS funding has supported galidesivir&rsquo;s development
    as a treatment for Marburg virus and Ebola virus. In March 2014, galidesivir was featured in an online <FONT STYLE="font-size: 10pt; font-weight: normal"><I>Nature
    </I><FONT STYLE="font-style: normal">publication depicting successful efficacy results in animal models of infection with
    Marburg virus and Ebola virus.&nbsp;Galidesivir completely protected cynomolgus macaques from Marburg virus infection when
    administered by intramuscular (&ldquo;i.m.&rdquo;) injection 48 hours post-infection. Post-exposure i.m. administration of
    galidesivir also protected rodents against Marburg virus and Ebola virus infections.&nbsp;In addition, galidesivir was shown
    to be active in vitro against a broad range of other RNA viruses, including the emerging viral pathogen Middle East Respiratory
    Syndrome Coronavirus.&nbsp;The publication, which reported the protection of non-human primates from filovirus disease by
    galidesivir, describes efficacy results generated from an ongoing collaboration between scientists in the U.S. Army Medical
    Research Institute of Infection Diseases (&ldquo;USAMRIID&rdquo;) and us.&nbsp;Galidesivir has been shown to be active against
    more than 20 RNA viruses in nine different families, including filoviruses, togaviruses, bunyaviruses, arenaviruses, paramyxoviruses,
    coronaviruses and flaviviruses.&nbsp;In tests conducted at USAMRIID, galidesivir protected animals against parenteral exposures
    to Marburg, Ebola and Rift Valley Fever viruses and from exposures to aerosolized Marburg virus, an experimental condition
    designed to mimic an exposure scenario that could result during a bioterrorist attack.</FONT></FONT></FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-bottom: Black 1.1pt solid; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle; border-bottom: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1.1pt solid; border-bottom: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
</TABLE>


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<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

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<TABLE BORDER="0" CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; border-collapse: collapse; font-size: 10pt">
<TR STYLE="vertical-align: bottom">
    <TD STYLE="width: 2%; border-top: Black 1.1pt solid; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 96%; border-top: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 2%; border-right: Black 1.1pt solid; border-top: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle; font-family: Arial, Helvetica, Sans-Serif"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">On December 15, 2014, we announced
    the dosing of the first subject in a randomized, placebo-controlled Phase 1 clinical trial to evaluate i.m. administration
    of galidesivir in healthy volunteers. The main goals of this first-in-human study are to evaluate the safety, tolerability
    and pharmacokinetics of escalating doses of galidesivir administered via i.m. injection in healthy subjects. In one part of
    the study, subjects received a single dose of galidesivir; in another part of the study, subjects received galidesivir for
    seven days. There were six single-dose cohorts and four multiple-dose cohorts evaluated, and 94 healthy volunteers participated.
    In August 2016, we reported the results of this study.&nbsp;&nbsp;Galidesivir administered by i.m. injection was generally
    safe and well tolerated over the range of doses up to 10 mg/kg, and durations tested (up to 7 days.)&nbsp;&nbsp;Seventy-six
    subjects received doses of study drug and there were no serious or severe adverse events.&nbsp;&nbsp;The most frequently reported
    adverse event across all cohorts was injection site pain and there were no clinically significant laboratory abnormalities
    which occurred at any doses.&nbsp;&nbsp;In addition, co-administration of lidocaine with galidesivir was determined to ameliorate
    injection site pain without altering the plasma pharmacokinetics profile of galidesivir. From this clinical trial, we determined
    galidesivir was safe and well tolerated, and that exposure was dose-proportional and supported the continued development of
    this BSAV drug candidate for serious emerging viral infections.&nbsp;</FONT></TD>
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<TR>
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<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">On December 23, 2014, we announced
    results from a successful proof-of-concept study of galidesivir for the treatment of experimental Ebola virus infection in
    Rhesus macaques, conducted at USAMRIID. The primary goal of the study was to assess the effect of galidesivir treatment on
    survival through Day 41 in animals infected with Ebola virus. Dosing of&nbsp;placebo or galidesivir by i.m. injection was
    initiated 30-120 minutes after virus challenge and continued twice a day (&ldquo;BID&rdquo;) for 14 days. Animals were dosed
    with either placebo, 16 mg/kg of galidesivir BID or 25 mg/kg of galidesivir BID. Survival at day 41 in the 16 mg/kg BID group
    of galidesivir treated animals was 4 of 6 (66.7%, p &lt; 0.001 compared to 0% survival in controls) and 6 of 6 in the 25 mg/kg
    BID group (100%, p &lt; 0.001 compared to controls). The overall survival rate for galidesivir treated animals at day 41 was
    10 of 12 (83%, p &lt; 0.001 compared to controls). Preliminary evaluation of the quantity of virus in the blood showed an
    approximate 3-log reduction in Ebola virus RNA copies/mL of plasma, compared with control animals. This Rhesus macaque study
    was conducted following the completion, in November 2014, of a dose-ranging study of galidesivir for the experimental treatment
    of cynomolgus macaques infected with Ebola virus. The cynomolgus macaque study was designed to evaluate whether galidesivir
    showed a meaningful benefit for survival in Ebola virus non-human primate disease models and explore a dose range. In this
    study galidesivir demonstrated a statistically significant prolongation of survival for the animals at the highest dose regimen
    tested, but no animals survived beyond 21 days.</FONT></TD>
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    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">On March 7, 2016, results from
    a preclinical study of our antiviral galidesivir in interferon-receptor-deficient mice infected with Zika virus were presented
    at a World Health Organization conference in Geneva, Switzerland. The primary goal of the study was to assess the effect of
    galidesivir treatment on survival through Day 28 in interferon-receptor-deficient mice infected with the Zika virus. Galidesivir
    was administered by i.m. injection twice a day beginning four hours prior to virus challenge and continuing for eight days;
    two dose levels were tested. In the standard dose galidesivir group, 7 of 8 mice survived through Day 28. In the low dose
    galidesivir group (n=8), and in control groups administered vehicle placebo (n=8) or ribavirin at two dose levels (n=16);
    no animals survived to Day 28. Overall survival for the standard dose level of galidesivir was superior to both the placebo
    and the ribavirin treatment control groups (p &lt; 0.0001). For both dose levels of galidesivir, median survival was superior
    to both control groups (&gt;28 days for galidesivir standard dose and 23 days for low dose) compared to 14 to 17 days for
    controls.&nbsp;</FONT></TD>
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<TR>
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    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Additional studies of galidesivir
    in the same mouse model were conducted at Utah State University. In one study, surviving mice that were previously treated
    with the standard dose of galidesivir after initial Zika virus challenge were re-challenged with the Zika virus on Day 28,
    without additional galidesivir treatment. All the re-challenged mice survived through day 56 with no disease signs observed,
    indicating the development of effective immune responses. A further experiment using the same AG129 mouse model tested the
    delayed treatment with galidesivir after viral challenge. Groups of mice received galidesivir 150 mg/kg twice-daily by i.m.
    injection starting on days 1, 3, 5, or 7 post infection, or vehicle (control group). All galidesivir treated groups showed
    a statistically significant survival benefit compared to vehicle controls.&nbsp;</FONT></TD>
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<TR>
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    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;On October 29, 2016, galidesivir
    nonclinical results from a Zika virus infection model were presented in a late-breaker scientific session at IDWeek by Dr.
    James B. Whitney, PhD, Assistant Professor of Medicine, Harvard Medical School, and Principal Investigator in the Center for
    Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston. Three groups of five healthy animals were
    inoculated with a Puerto Rico strain of Zika virus and administered either galidesivir by i.m. injection 200 mg/kg loading
    dose followed by 25 mg/kg BID for nine days, galidesivir single dose of 200 mg/kg, or vehicle control. Both galidesivir groups
    showed reduction in the proportion of animals viremic and in the amount of virus shed of into cerebrospinal fluid, saliva
    and urine. Galidesivir dosing in rhesus macaques was well-tolerated and offered significant protection against Zika virus
    infection. In a follow-on experiment, the same animals were rechallenged with a Thai strain of Zika virus, 72 days after initial
    inoculation. All animals demonstrated immune responses, and the initial treatments with galidesivir did not impair the generation
    of immunity.&nbsp;</FONT></TD>
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    <TD STYLE="font-weight: bold; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Financial outlook
    for 2017</FONT></TD>
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<TR>
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    <TD STYLE="font-weight: bold; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
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<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1.1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Based upon our development plans, expected operations and our awarded government contracts, we expect 2017 operating
cash usage to be in the range of $30 to $50 million, and expect our total 2017 operating expenses to be in the range of $53 to
$73 million. Our operating expense range excludes equity-based compensation expense due to the difficulty in accurately projecting
this expense as it is significantly impacted by the volatility and price of our stock, as well as vesting of our outstanding performance-based
stock options. Our operating cash forecast excludes any impact of our royalty monetization, hedge collateral posted or returned,
and any other non-routine cash outflows or inflows. Our ability to remain within our operating expense and operating cash target
ranges is subject to multiple factors, including unanticipated or additional general development and administrative costs and other
factors described under the &ldquo;Risk factors&rdquo; section located elsewhere in this prospectus supplement, the accompanying
prospectus and in the documents incorporated herein by reference.</FONT></TD>
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    <TD STYLE="vertical-align: middle; text-align: center"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">________________________</FONT></TD>
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    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We are a Delaware corporation originally
    founded in 1986. Our principal executive offices are located at 4505 Emperor Blvd., Suite 200, Durham, North Carolina 27703,
    and our telephone number is (919) 859-1302. Our website is located at http://www.biocryst.com. The information on our website
    is not incorporated by reference into this prospectus supplement or the accompanying prospectus.</FONT></TD>
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    offering</FONT></TD>
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    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-style: italic; vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Common
    stock offered&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">5,294,118  shares of common
    stock</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: left; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Option
    to purchase additional shares&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Up to 794,117 shares of common stock</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: left; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Common
    stock to be outstanding after the offering&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">79,313,398 shares of common stock</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: left; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Use
    of proceeds&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We intend to use the net proceeds
    of this offering for general corporate purposes, including future clinical development of BCX7353, continued development of
    our second generation HAE compounds, including for other indications, and the advancement of our other preclinical rare disease
    programs. See &ldquo;Use of Proceeds.&rdquo;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: left; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">NASDAQ
    global select market symbol&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">BCRX</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: left; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Dividend
    policy</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We have never paid cash dividends
    and do not anticipate paying cash dividends in the foreseeable future.&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: left; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Risk
    factors&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">See &ldquo;Risk factors&rdquo; beginning on page S-8 and the other information included in, or incorporated
by reference into, this prospectus supplement and the accompanying prospectus for a discussion of certain factors you should carefully
consider before deciding to invest in shares of our common stock.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: middle"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="3" STYLE="vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT>

<P STYLE="font-size: 10pt; margin: 0pt 0">The number of shares to be outstanding after this offering is based on 74,019,280 shares
outstanding as of March 7, 2017 and excludes:</P>



<FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="3" STYLE="vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: center; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;&bull;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">13,906,904
    shares of common stock issuable upon the exercise of stock options outstanding under our Stock Incentive Plan as of February
    28, 2017, at a weighted average exercise price of $6.21 per share;&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: center; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: center; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;&bull;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">220,373
    shares of common stock issuable upon the vesting of restricted stock units outstanding as of February 28, 2017; and</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: center; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: center; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;&bull;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">458,478
    additional shares of common stock reserved for issuance under our Stock Incentive Plan and 363,646 additional shares of common
    stock reserved for issuance under our Employee Stock Purchase Plan as of February 28, 2017.&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: left; vertical-align: top"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="2" STYLE="vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="3" STYLE="vertical-align: middle; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Except
    as otherwise noted, all information in this prospectus supplement assumes no exercise of the outstanding stock options, no
    vesting of the outstanding restricted stock units and no exercise of the underwriters&rsquo; option to purchase additional
    shares of our common stock.</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: bottom; border-left: Black 1pt solid; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="3" STYLE="vertical-align: middle; text-align: left; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-right: Black 1pt solid; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
</TABLE>


<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font: 10pt Arial, Helvetica, Sans-Serif; text-transform: none"><B></B></FONT></P>

<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt; text-transform: none"><B>&nbsp;</B></FONT></P>

<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 16pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; text-transform: none"><B>Risk
factors</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><I>An
investment in our common stock involves risks. You should consider carefully all of the information that is included or incorporated
by reference in this prospectus supplement and the accompanying prospectus before investing in our common stock. In particular,
you should evaluate the uncertainties and risks referred to or described below, which may adversely affect our business, financial
condition, liquidity, results of operations, or prospects, along with all of the other information included in our other filings
with the SEC, before deciding to buy our common stock.</I></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><I>&nbsp;</I></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Risks
relating to our business</B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
have incurred losses since our inception, expect to continue to incur such losses, and may never be profitable.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Since
our inception, we have not achieved sustained profitability. We expect to incur additional losses for the foreseeable future,
and our losses could increase as our research and development efforts progress. We expect that such losses will fluctuate from
quarter to quarter and losses and fluctuations may be substantial.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">To
become profitable, we, or our collaborative partners, must successfully manufacture and develop product candidates, receive regulatory
approval, and successfully commercialize and/or enter into profitable agreements with other parties. It could be several years,
if ever, before we receive significant revenue from any current or future license agreements or revenues directly from product
sales.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Because
of the numerous risks and uncertainties associated with developing our product candidates and their potential for commercialization,
we are unable to predict the extent of any future losses. Even if we do achieve profitability, we may not be able to sustain or
increase profitability on a quarterly or annual basis. If we are unable to achieve and sustain profitability, the market value
of our common stock will likely decline.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Our
success depends upon our ability to advance our products through the various stages of development, especially through the clinical
trial process.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">To
receive the regulatory approvals necessary for the sale of our product candidates, we or our partners must demonstrate through
preclinical studies and clinical trials that each product candidate is safe and effective. The development process and related
regulatory process are complex and uncertain. Because of the cost and duration of clinical trials, we may decide to discontinue
development of product candidates that are unlikely to show good results in the clinical trials, unlikely to help advance a product
to the point of a meaningful collaboration, or unlikely to have reasonable commercial potential. We may suffer significant setbacks
in pivotal pre-clinical studies and clinical trials (e.g. galidesivir, BCX7353, other kallikrein inhibitors and our other rare
disease product candidates), even after earlier clinical trials show promising results. The development of our product candidates,
including our clinical trials, may not be adequately designed or executed, which could affect the potential outcome and analysis
of study results. Any of our product candidates may produce undesirable side effects in humans. The pre-clinical and clinical
data from our product candidates could cause us or regulatory authorities to interrupt, delay, modify or halt preclinical or clinical
trials of a product candidate. Undesirable or inconclusive data or side effects in humans could also result in the FDA or foreign
regulatory authorities refusing to approve the product candidate for any targeted indications. In addition, the FDA or other regulatory
agencies may determine that study data from our product candidates necessitates additional studies or study designs which differ
from our planned development strategy, and regulatory agencies may also require patient monitoring and testing or may implement
restrictions or other conditions on our development activities, any of which could materially impact the cost and timing of our
planned development strategy. We, our partners, the FDA or foreign regulatory authorities may suspend or terminate clinical trials
at any time if we or they believe the trial participants face unacceptable health risks. Clinical trials may fail to demonstrate
that our product candidates are safe or effective and have acceptable commercial viability. Regulatory authorities may interrupt,
delay or halt clinical trials for a product candidate for any number of reasons.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
ability to successfully complete clinical trials is dependent upon many factors, including but not limited to:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to find suitable clinical sites and investigators to enroll patients;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

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<P STYLE="margin-top: 0; margin-bottom: 0"></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         ability to maintain contact with patients to provide complete data after treatment;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         product candidates may not prove to be either safe or effective;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">clinical
                                         protocols or study procedures may not be adequately designed or followed by the investigators;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">formulation
                                         improvements may not work as expected, which could negatively impact commercial demand
                                         for our product candidates;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">manufacturing
                                         or quality control problems could affect the supply of product candidates for our trials;
                                         and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">delays
                                         or changes in our planned development strategy, the regulations or guidelines, or other
                                         unexpected conditions or requirements of government agencies.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Clinical
trials are lengthy and expensive. We or our partners incur substantial expense for, and devote significant time to, preclinical
testing and clinical trials, yet we cannot be certain that the tests and trials will ever result in the commercial sale of a product.
For example, clinical trials require adequate supplies of drug and sufficient patient enrollment. Lack of adequate drug supply
or delays in patient enrollment can result in increased costs and longer development times. Even if we or our partners successfully
complete clinical trials for our product candidates, we or our partners might not file the required regulatory submissions in
a timely manner and may not receive regulatory approval for the product candidates.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
focus on rare diseases, which may create additional risks and challenges.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Because
we focus on developing drugs as treatments for rare diseases, we may seek orphan drug, breakthrough therapy or fast track designations
for our product candidates in the United States or the equivalent designations elsewhere in the world. Often, regulatory agencies
have broad discretion in determining whether or not to grant such designations. We cannot guarantee that we will be able to receive
orphan drug status from the FDA or equivalent regulatory designations elsewhere. We also cannot guarantee that we will obtain
breakthrough therapy or fast track designation, which may provide certain potential benefits such as more frequent meetings with
the FDA to discuss the development plan, intensive guidance on an efficient drug development program, and potential eligibility
for rolling review or priority review. Even if we are successful in obtaining any such designation by the FDA or other regulatory
agency for our product candidates, such designations may not lead to faster development or regulatory review or approval, and
it does not increase the likelihood that our product candidates will receive marketing approval. We may not be able to obtain
or maintain such designations for our product candidates, and our competitors may obtain these designations for their product
candidates, which could impact our ability to develop and commercialize our product candidates or compete with such competitors,
which may adversely impact our business, financial condition or results of operations.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Although
we have received Sakigake designation for BCX7353 in Japan, we may not experience a faster development, review or approval process
compared to the conventional process.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Our
clinical trials may not adequately show that our product candidates are safe or effective.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Progression
of our product candidates through the clinical development process is dependent upon our trials indicating our product candidates
have adequate safety and efficacy in the patients being treated by achieving pre-determined safety and efficacy endpoints according
to the clinical trial protocols. Failure to achieve any of these endpoints in any of our programs, including BCX7353 and our other
rare disease product candidates, could result in delays in our trials or require the performance of additional unplanned trials.
This could result in delays in the development of our product candidates and could result in significant unexpected costs or the
termination of programs.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>If
our development collaborations with third parties, such as our development partners and contract research organizations, fail,
the development of our product candidates will be delayed or stopped.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
rely heavily upon third parties for many important stages of our product candidate development, including but not limited to:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">discovery
                                         of compounds that cause or enable biological reactions necessary for the progression
                                         of the disease or disorder, called enzyme targets;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">licensing
                                         or designing of enzyme inhibitors for development as product candidates;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in">&bull;</TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">execution
                                         of certain preclinical studies and late-stage development for our compounds and product
                                         candidates;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">management
                                         of our clinical trials, including medical monitoring and data management;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">execution
                                         of additional toxicology studies that may be required to obtain approval for our product
                                         candidates;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">formulation
                                         improvement strategies and methods; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">manufacturing
                                         the starting materials and drug substance required to formulate our products and the
                                         product candidates to be used in our clinical trials, toxicology studies and any potential
                                         commercial product.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
failure to engage in successful collaborations at any one of these stages would greatly impact our business. If we do not license
enzyme targets or inhibitors from academic institutions or from other biotechnology companies on acceptable terms, our drug development
efforts would suffer. Similarly, if the contract research organizations that conduct our initial or late-stage clinical trials,
conduct our toxicology studies, manufacture our starting materials, drug substance and product candidates or manage our regulatory
function breached their obligations to us or perform their services inconsistent with industry standards and not in accordance
with the required regulations, this would delay or prevent both the development of our product candidates and the availability
of any potential commercial product.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If
we lose our relationship with any one or more of these parties, we could experience a significant delay in both identifying another
comparable provider and then contracting for its services. We may be unable to retain an alternative provider on reasonable terms,
if at all. Even if we locate an alternative provider, it is likely that this provider may need additional time to respond to our
needs and may not provide the same type or level of service as the original provider. In addition, any provider that we retain
will be subject to applicable FDA current Good Laboratory Practices, current Good Manufacturing Practices (&ldquo;cGMP&rdquo;)
and current Good Clinical Practices, and comparable foreign standards. We do not have control over compliance with these regulations
by these providers. Consequently, if these practices and standards are not adhered to by these providers, the development and
commercialization of our product candidates could be delayed. If any of the foregoing risks are realized, our business, financial
condition and results of operations could be materially adversely affected.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Because
we have limited manufacturing experience, we depend on third-party manufacturers to manufacture our product, product candidates
and the materials for our product candidates. Often, especially early in the development and commercialization process, we have
only one source for manufacturing. If we cannot rely on existing third-party manufacturers, we will be required to incur significant
costs and potential delays in finding new third-party manufacturers.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
have limited manufacturing experience and only a small scale manufacturing facility. We currently rely upon a very limited number
of third-party manufacturers to manufacture the materials required for our product, product candidates and most of the preclinical
and clinical quantities of our product candidates. We depend on these third-party manufacturers to perform their obligations in
a timely manner and in accordance with applicable governmental regulations. Our third-party manufacturers, which may be the only
manufacturer we have engaged for a particular product, may encounter difficulties with meeting our requirements, including but
not limited to problems involving:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">inconsistent
                                         production yields;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">product
                                         liability claims or recalls of commercial product;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">difficulties
                                         in scaling production to commercial and validation sizes;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">interruption
                                         of the delivery of materials required for the manufacturing process;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">scheduling
                                         of plant time with other vendors or unexpected equipment failure;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">potential
                                         catastrophes that could strike their facilities or have an effect on infrastructure;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">potential
                                         impurities in our drug substance or products that could affect availability of product
                                         for our clinical trials or future commercialization;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">poor
                                         quality control and assurance or inadequate process controls; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">lack
                                         of compliance or cooperation with regulations and specifications or requests set forth
                                         by the FDA or other foreign regulatory agencies, particularly associated with peramivir,
                                         BCX7353, galidesivir and our early stage compounds.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">These
contract manufacturers may not be able to manufacture the materials required for our product candidates at a cost or in quantities
necessary to make them commercially viable. We also have no control over whether third-party manufacturers breach their agreements
with us or whether they may terminate or decline to renew agreements with us. To date, our third-party manufacturers have met
our manufacturing requirements, but they may not continue to do so. Furthermore, changes in the manufacturing process or procedure,
including a change in the location where the drug is manufactured or a change of a third-party manufacturer, may require prior
review and approval in accordance with the FDA&rsquo;s cGMP and comparable foreign requirements. This review may be costly and
time-consuming and could delay or prevent the launch of a product. The FDA or similar foreign regulatory agencies may at any time
implement new standards, or change their interpretation and enforcement of existing standards for manufacture, packaging or testing
of products. If we or our contract manufacturers are unable to comply, we or they may be subject to regulatory action, civil actions
or penalties any of which could be costly to the Company and could result in a delay or shortage of product.</FONT></P>

<P STYLE="font-size: 10pt; text-align: justify; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If
we are unable to maintain current manufacturing or other contract relationships, or enter into new agreements with additional
manufacturers on commercially reasonable terms, or if there is poor manufacturing performance or failure to comply with any regulatory
agency on the part of any of our third-party manufacturers, we may not be able to complete development of, seek timely approval
of, or market, our product candidates.</FONT></P>

<P STYLE="font-size: 10pt; text-align: justify; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
raw materials, drug substances, and product candidates are manufactured by a limited group of suppliers, including some at a single
facility. If any of these suppliers were unable to produce these items, this could significantly impact our supply of product
candidate material for further preclinical testing and clinical trials.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
face intense competition, and if we are unable to compete effectively, the demand for our products, if any, may be reduced.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
biotechnology and pharmaceutical industries are highly competitive and subject to rapid and substantial technological change.
There are many companies seeking to develop products for the same indications that we currently target. Our competitors in the
United States and elsewhere are numerous and include, among others, major multinational pharmaceutical and chemical companies
and specialized biotechnology firms. Most of these competitors have greater resources than we do, including greater financial
resources, larger research and development staffs and more experienced marketing and manufacturing organizations. In addition,
most of our competitors have greater experience than we do in conducting clinical trials and obtaining FDA and other regulatory
approvals. Accordingly, our competitors may succeed in obtaining FDA or other regulatory approvals of product candidates more
rapidly than we do. Companies that complete clinical trials, obtain required regulatory approvals, and commence commercial sale
of their drugs before we do may achieve a significant competitive advantage, including patent and FDA exclusivity rights that
would delay our ability to market products. We face, and will continue to face, competition in the licensing of potential product
candidates for desirable disease targets, licensing of desirable product candidates, and development and marketing of our product
candidates from academic institutions, government agencies, research institutions and biotechnology and pharmaceutical companies.
Competition may also arise from, among other things:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">other
                                         drug development technologies;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">methods
                                         of preventing or reducing the incidence of disease, including vaccines; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">new
                                         small molecule or other classes of therapeutic agents.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Developments
by others may render our product candidates or technologies obsolete or noncompetitive.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
are performing research on or developing products for the treatment of several rare disorders, including HAE, as well as developing
broad spectrum antivirals for use as medical countermeasures. We expect to encounter significant competition for any of the pharmaceutical
products we plan to develop. Companies that complete clinical trials, obtain required funding or government support, obtain required
regulatory approvals and commence commercial sales or stockpiling orders of their products before their competitors may achieve
a significant competitive advantage. Such is the case with the current neuraminidase inhibitors marketed by GSK and Roche for
influenza; CINRYZE&reg;, KALBITOR&reg; and FIRAZYR&reg;, marketed by Shire Pharmaceuticals, Inc. for HAE; and BERINERT&reg;, marketed
by CSL for HAE. Therapeutic products with potentially promising data to treat Ebola include Mapp Biopharmaceutical, Inc.&rsquo;s
ZMapp (antibody-based) and Gilead Sciences, Inc.&rsquo;s product currently under development (small molecule), both of which have
been used in Ebola infected patients. Further, several pharmaceutical and biotechnology firms, including major pharmaceutical
companies and specialized structure-based drug design companies, have announced efforts in the field of structure-based drug design
and molecules in development in the fields of HAE and in other therapeutic areas where we have discovery and development efforts
ongoing. If one or more of our competitors&rsquo; products or programs are successful, the market for our products may be reduced
or eliminated.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Compared
to us, many of our competitors and potential competitors have substantially greater:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">capital
                                         resources;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">research
                                         and development resources, including personnel and technology;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">regulatory
                                         experience;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">preclinical
                                         study and clinical testing experience;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">manufacturing
                                         and marketing experience; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">production
                                         facilities.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Any
of these competitive factors could impede our funding efforts, render technology and product candidates noncompetitive or eliminate
or reduce demand for our product candidates.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
face risks related to our government-funded programs; if BARDA/HHS or NIAID/HHS were to eliminate, reduce or delay funding from
our contracts, this would have a significant negative impact on the programs associated with such funding and could have a significant
negative impact on our revenues and cash flows.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
projections of revenues and incoming cash flows are substantially dependent upon BARDA/HHS and NIAID/HHS reimbursement for the
costs related to our galidesivir program. If BARDA/HHS or NIAID/HHS were to eliminate, reduce or delay the funding for these programs
or disallow some of our incurred costs, we would have to obtain additional funding for continued development or regulatory registration
for these product candidates or significantly reduce or stop the development effort.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
contracting with BARDA/HHS and NIAID/HHS, we are subject to various U.S. Government contract requirements, including general clauses
for a cost-reimbursement research and development contract, which may limit our reimbursement or if we are found to be in violation
could result in contract termination. If the U.S. Government terminates any of its contracts with us for its convenience, or if
we default by failing to perform in accordance with the contract schedule and terms, significant negative impact on our cash flows
and operations could result.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Our
government contracts with BARDA/HHS and NIAID/HHS have special contracting requirements, which create additional risks of reduction
or loss of funding.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
have completed work under a contract with BARDA/HHS for the development of our neuraminidase inhibitor, RAPIVAB. We also have
entered into contracts with BARDA/HHS and NIAID/HHS for the development of galidesivir as a treatment for diseases caused by RNA
pathogens, including Marburg virus disease and Ebola virus disease. In contracting with these government agencies, we are subject
to various U.S. Government contract requirements, including general clauses for a cost-reimbursement research and development
contract, which may limit our reimbursement or, if we are found to be in violation, could result in contract termination.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">U.S.
Government contracts typically contain a number of extraordinary provisions that would not typically be found in commercial contracts
and which may create a disadvantage and additional risks to us as compared to competitors that do not rely on U.S. Government
contracts.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">These
risks include the ability of the U.S. Government to unilaterally:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">terminate
                                         or reduce the scope of our contract with or without cause;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">interpret
                                         relevant regulations (federal acquisition regulation clauses);</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">require
                                         performance under circumstances which may not be favorable to us;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">require
                                         an in process review where the U.S. Government will review the project and its options
                                         under the contract;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">control
                                         the timing and amount of funding, which impacts the development progress of our programs;
                                         and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">audit
                                         and object to our contract-related costs and fees, including allocated indirect costs.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Our
government contracts with BARDA/HHS and NIAID/HHS have termination and audit provisions which create additional risks to us.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
U.S. Government may terminate its contracts with us either for its convenience or if we default by failing to perform in accordance
with the contract schedule and terms. Termination for convenience provisions generally enable us to recover only our costs incurred
or committed, and settlement expenses and profit on the work completed prior to termination. Termination does not permit these
recoveries under default provisions. In the event of termination or upon expiration of a contract, the U.S. Government may dispute
wind-down and termination costs and may question prior expenses under the contract and deny payment of those expenses. Should
we choose to challenge the U.S. Government for denying certain payments under a contract, such a challenge could subject us to
substantial additional expenses which we may or may not recover. Further, if the U.S. Government terminates its contracts with
us for its convenience, or if we default by failing to perform in accordance with the contract schedule and terms, significant
negative impact on our cash flows and operations could result.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">As
a U.S. Government contractor, we are required to comply with applicable laws, regulations and standards relating to our accounting
practices and are subject to periodic audits and reviews. As part of any such audit or review, the U.S. Government may review
the adequacy of, and our compliance with, our internal control systems and policies, including those relating to our purchasing,
property, estimating, compensation and management information systems. Audits conducted by the U.S. Government for the completed
BARDA/HHS peramivir contract have been performed and concluded through fiscal 2009; all subsequent fiscal years are still open
and auditable. Audits under the active BARDA/HHS and NIAID/HHS galidesivir contracts may occur at the election of the U.S. Government
and have been concluded through fiscal 2013. Based on the results of its audits, the U.S. Government may adjust our contract-related
costs and fees, including allocated indirect costs. This adjustment could impact the amount of revenues reported on a historic
basis and could impact our cash flows under the contracts prospectively. In addition, in the event BARDA/HHS or NIAID/HHS determines
that certain costs and fees were unallowable or determines that the allocated indirect cost rate was higher than the actual indirect
cost rate, BARDA/HHS or NIAID/HHS would be entitled to recoup any overpayment from us as a result. In addition, if an audit or
review uncovers any improper or illegal activity, we may be subject to civil and criminal penalties and administrative sanctions,
including termination of our contracts, forfeiture of profits, suspension of payments, fines and suspension or prohibition from
doing business with the U.S. Government. We could also suffer serious harm to our reputation if allegations of impropriety were
made against us. In addition, under U.S. Government purchasing regulations, some of our costs may not be reimbursable or allowed
under our contracts. Further, as a U.S. Government contractor, we are subject to an increased risk of investigations, criminal
prosecution, civil fraud, whistleblower lawsuits and other legal actions and liabilities as compared to private sector commercial
companies.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>If
we fail to reach milestones or to make annual minimum payments or otherwise breach our obligations under our license agreements,
our licensors may terminate our agreements with them and seek additional remedies.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If
we are unable or fail to meet payment obligations, performance milestones relating to the timing of regulatory filings, product
supply obligations, post approval commitments for RAPIVAB, or development and commercial diligence obligations; are unable or
fail to make milestone payments or material data use payments in accordance with applicable provisions; or fail to pay the minimum
annual payments under our respective licenses, our licensors may terminate the applicable license or seek other available remedies.
As a result, our development of the respective product candidate or commercialization of the product would cease.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>If
we fail to obtain additional financing or acceptable partnership arrangements, we may be unable to complete the development and
commercialization of our product candidates or continue operations.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">As
our programs advance, our costs are likely to increase. Our current and planned discovery activities, pre-clinical and clinical
trials, the related development, manufacturing, regulatory approval process requirements, and the additional personnel resources
and testing required for supporting the development of our product candidates will consume significant capital resources. Our
expenses, revenues and cash utilization rate could vary significantly depending on many factors, including: our ability to raise
additional capital; the development progress of our collaborative agreements for our product candidates; the amount of funding
we receive from NIAID/HHS and BARDA/HHS for galidesivir or from other new partnerships with third parties for the development
of our product candidates, including BCX7353 and our other rare disease product candidates; the commercial success of peramivir
achieved by our partners; the amount or profitability of any orders for peramivir or galidesivir by any government agency or other
party; the progress and results of our current and proposed clinical trials for our most advanced product candidates, including
BCX7353 and our other rare disease product candidates; the progress made in the manufacture of our lead products and the progression
of our other programs.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
expect that we will be required to raise additional capital to complete the development and commercialization of our current product
candidates and we may seek to raise capital at any time. Additional funding, whether through additional sales of securities, additional
borrowings, or collaborative arrangements with partners, including governmental agencies in general and from any BARDA/HHS or
NIAID/HHS contract specifically, may not be available when needed or on terms acceptable to us. The issuance of preferred or common
stock or convertible securities, with terms and prices significantly more favorable than those of the currently outstanding common
stock, could have the effect of diluting or adversely affecting the holdings or rights of our existing stockholders. Additional
borrowings may subject us to more restrictive covenants than are currently applicable to us under our September 23, 2016, Senior
Credit Facility with an affiliate of MidCap Financial Services, LLC, as administrative agent (the &ldquo;Senior Credit Facility&rdquo;).
In addition, collaborative arrangements may require us to transfer certain material rights to such corporate partners. Insufficient
funds or lack of an acceptable partnership may require us to delay, scale-back or eliminate certain of our research and development
programs.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
order to continue future operations and continue our drug development programs, we will be required to raise additional capital.
In addition to seeking strategic partnerships, transactions and government funding, we may decide to access the equity or debt
markets, incur additional borrowings, or seek other sources to meet liquidity needs. Our ability to raise additional capital may
be limited and may greatly depend upon the success of ongoing development related to our current drug development programs, including
post approval studies for RAPIVAB,&nbsp;the progress, timeline and ultimate outcome of&nbsp;our kallikrein inhibitors, including
the BCX7353 program (including, but not limited to, formulation progress, phase 3 trials, long-term human safety studies, and
the timing of carcinogenicity or other required studies), the progress of our other rare disease product candidates, funding for
and continued successful development of galidesivir, and the progress of our early discovery programs. In addition, constriction
and volatility in the equity and debt markets may restrict our future flexibility to raise capital when such needs arise. Furthermore,
we have exposure to many different industries, financing partners and counterparties, including commercial banks, investment banks
and partners (which include investors, licensing partners, and the U.S. Government) which may be unstable or may become unstable
in the current economic and political environment. Any such instability may impact these parties&rsquo; ability to fulfill contractual
obligations to us or they might limit or place burdensome conditions upon future transactions with us. Also, it is possible that
suppliers may be negatively impacted. Any such unfavorable outcomes in our current programs or unfavorable economic conditions
could place severe downward pressure on the price of our common stock and may decrease opportunities to raise capital in the capital
or credit markets, and further could reduce the return available on invested corporate cash, which, if severe and sustained, could
have a material and adverse impact on our results of operations and cash flows and limit our ability to continue development of
our product candidates.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
may not be able to continue as a going concern if we do not obtain additional capital.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
have sustained operating losses for the majority of our corporate history and expect that our 2017 expenses will exceed our 2017
revenues. We expect to continue to incur operating losses and negative cash flows until revenues reach a level sufficient to support
ongoing operations.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
liquidity needs will be largely determined by the success of operations in regards to the progression of our product candidates
in the future. Our plans to alleviate the doubt regarding our ability to continue as a going concern primarily include our ability
to control the timing and spending on our research and development programs and raising additional funds through equity financings.
We also may consider other plans to fund operations including: (1) securing or increasing U.S. Government funding of our programs,
including obtaining procurement contracts; (2) out-licensing rights to certain of our products or product candidates, pursuant
to which the we would receive cash milestones; (3) raising additional capital through debt financings or from other sources; (4)
obtaining additional product candidate regulatory approvals, which would generate revenue, milestones and cash flow; (5) reducing
spending on one or more research and development programs by discontinuing development; and/or (6) restructuring operations to
change our overhead structure.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">There
can be no assurance that any of our plans will be successful or that additional capital will be available to us on reasonable
terms, or at all, when needed. If we are unable to obtain sufficient additional capital, we may be forced to curtail operations,
delay or stop ongoing clinical trials, cease operations altogether or file for bankruptcy.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>If
we fail to successfully commercialize or establish collaborative relationships to commercialize certain of our product candidates,
or if any partner terminates or fails to perform its obligations under agreements with us, potential revenues from commercialization
of our product candidates could be reduced, delayed or eliminated.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
business strategy is to increase the asset value of our product candidate portfolio. We believe this is best achieved by retaining
full product rights or through collaborative arrangements with third parties as appropriate. As needed, potential third-party
relationships could include preclinical development, clinical development, regulatory approval, marketing, sales and distribution
of our product candidates.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Currently,
we have established collaborative relationships with Mundipharma for the development and commercialization of forodesine and with
each of Shionogi and Green Cross for the development and commercialization of peramivir in Japan, Taiwan and South Korea. Most
recently we have established a collaborative relationship with Seqirus UK Limited for RAPIVAB on a worldwide basis other than
Israel, Japan, Korea and Taiwan. The process of establishing and implementing collaborative relationships is difficult, time-consuming
and involves significant uncertainty, including:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         partners may seek to renegotiate or terminate their relationships with us due to unsatisfactory
                                         clinical results, including post approval clinical commitments, a change in business
                                         strategy, a change of control or other reasons;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         contracts for collaborative arrangements may expire;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         partners may choose to pursue alternative technologies, including those of our competitors;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

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<P STYLE="margin-top: 0; margin-bottom: 0"></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">we
                                         may have disputes with a partner that could lead to litigation or arbitration;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">we
                                         do not have day to day control over the activities of our partners and have limited control
                                         over their decisions;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to generate future event payments and royalties from our partners depends upon
                                         their abilities to establish the safety and efficacy of our product candidates, obtain
                                         regulatory approvals and achieve market acceptance of products developed from our product
                                         candidates;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">we
                                         or our partners may fail to properly initiate, maintain or defend our intellectual property
                                         rights, where applicable, or a party may utilize our proprietary information in such
                                         a way as to invite litigation that could jeopardize or potentially invalidate our proprietary
                                         information or expose us to potential liability;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">we
                                         or our partners may not devote sufficient capital or resources towards our product candidates;
                                         and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">we
                                         or our partners may not comply with applicable government regulatory requirements.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If
we or our partners fail to fulfill our responsibilities in a timely manner, or at all, our commercialization efforts related to
that collaboration could be reduced, delayed or terminated, or it may be necessary for us to assume responsibility for activities
that would otherwise have been the responsibility of our partner. If we are unable to establish and maintain collaborative relationships
on acceptable terms, we may have to delay or discontinue further development of one or more of our product candidates, undertake
commercialization activities at our own expense or find alternative sources of funding. Any delay in the development or commercialization
of our product candidates would severely affect our business, because if our product candidates do not progress through the development
process or reach the market in a timely manner, or at all, we may not receive additional future event payments and may never receive
milestone, product sales or royalty payments.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
do not have a great deal of experience in commercializing our products or technologies, and our future revenue generation is uncertain.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
do not have a great deal of experience in commercializing our product candidates or technologies. We currently have limited marketing
and commercial capability, no direct or third-party sales force and limited distribution capabilities. We may be unable to establish
or sufficiently increase these capabilities for products we currently, or plan to, commercialize. In addition, our revenue from
collaborative agreements may be dependent upon the status of our preclinical and clinical programs.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
ability to receive revenue from products we commercialize presents several risks, including:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">we
                                         or our collaborators may fail to successfully complete clinical trials, or satisfy post-marketing
                                         commitments, sufficient to obtain and keep FDA marketing approval;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">many
                                         competitors are more experienced and have significantly more resources, and their products
                                         could reach the market faster, be more cost effective or have a better efficacy or tolerability
                                         profile than our product candidates;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">we
                                         may fail to employ a comprehensive and effective intellectual property strategy, which
                                         could result in decreased commercial value of our Company and our products;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">we
                                         may fail to employ a comprehensive and effective regulatory strategy, which could result
                                         in a delay or failure in commercialization of our products;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to successfully commercialize our products is affected by the competitive landscape,
                                         which cannot be fully known at this time;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">reimbursement
                                         is constantly changing, which could greatly affect usage of our products; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

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<P STYLE="margin-top: 0; margin-bottom: 0"></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">future
                                         revenue from product sales would depend on our ability to successfully complete clinical
                                         studies, obtain regulatory approvals, and manufacture, market and commercialize our approved
                                         drugs.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Commercialization
of peramivir by our partners is subject to the potential commercialization risks described herein and numerous additional risks.
Any potential revenue benefits to us in the form of milestone payments, royalties or other consideration are highly speculative.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Commercialization
success of peramivir is uncertain and is subject to all the risks and uncertainties disclosed in our other risk factors relating
to drug development and commercialization. In addition, commercialization of peramivir products is subject to further risks and
may be negatively impacted by a number of factors, including, but not limited to, the following:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">peramivir
                                         may not prove to be adequately safe and effective for market approval in markets other
                                         than the United States, Japan, Korea and Taiwan;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">necessary
                                         funding for post-marketing commitments and further development of peramivir may not be
                                         available timely, at all, or in sufficient amounts;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">flu
                                         prevention or pandemic treatment concerns may not materialize at all, or in the near
                                         future;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">advances
                                         in flu vaccines or other antivirals, including competitive i.v. antivirals, could substantially
                                         replace potential demand for peramivir ;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">a
                                         limited number of governmental entities are expected to be the primary potential stockpiling
                                         customers for peramivir and if we are not successful at marketing peramivir to these
                                         entities for any reason, we will not receive substantial revenues from stockpiling orders;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">government
                                         and third party payors may not provide sufficient coverage or reimbursement which would
                                         negatively impact the demand for peramivir ;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">we
                                         may not be able to supply commercial material to our partners and our partners may not
                                         be able to maintain or establish sufficient and acceptable commercial manufacturing,
                                         either directly or through third-party manufacturers;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         commercial demand and acceptance for peramivir by healthcare providers and by patients
                                         may not be sufficient to result in substantial revenues of peramivir to our partners
                                         and may result in little to no milestones or royalties to us;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">effectiveness
                                         of marketing and commercialization efforts for peramivir by our partners;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">market
                                         satisfaction with existing alternative therapies;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">perceived
                                         efficacy relative to other available therapies;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">disease
                                         prevalence;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">cost
                                         of treatment;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">pricing
                                         and availability of alternative products;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">marketing
                                         and sales activities of competitors;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">shifts
                                         in the medical community to new treatment paradigms or standards of care; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">relative
                                         convenience and ease of administration.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
are subject to various federal and state laws related to RAPIVAB and other products under development and, if we or our partners
do not comply with these regulations, we could face substantial penalties.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
or our partners&rsquo; activities related to RAPIVAB, or any of our other products under development and following their regulatory
approval, are subject to regulatory and law enforcement authorities in addition to the FDA, including the Federal Trade Commission,
the Department of Justice, and state and local governments. In the case of our collaboration with SUL, although SUL is responsible
for RAPIVAB marketing and commercialization efforts, we continue to carry certain risks associated with RAPIVAB because we hold
the RAPIVAB NDA. For example, we are responsible for reporting adverse drug experiences, we have responsibility for certain post-approval
studies, we may have responsibilities and costs related to a recall or withdrawal of RAPIVAB from sale, we may incur liability
associated with RAPIVAB manufacturing contracted by us or in support of any of our partners, we are required to maintain records
and provide data and reports to regulatory agencies related to RAPIVAB (e.g. risk evaluation and mitigation strategies, track
and trace requirements, adverse events), and we may incur certain promotional regulatory and government pricing risks, all of
which could have a material adverse impact on our operations and financial condition.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
addition, we are subject to the federal physician sunshine act and certain similar physician payment and drug pricing transparency
legislation in various states. We are also subject to various federal and state laws pertaining to health care &ldquo;fraud and
abuse,&rdquo; including both federal and state anti-kickback and false claims laws. These laws regulate our or our partners&rsquo;
operations, sales and marketing practices, price reporting, and relationships with physicians and other customers and third-party
payors. Anti-kickback laws generally prohibit a manufacturer from soliciting, offering, receiving, or paying any remuneration
to generate business, including the purchase or prescription of a particular drug. Although the specific provisions of these laws
vary, their scope is generally broad and there may be no regulations, guidance or court decisions that clarify how the laws apply
to particular industry practices. False claims laws prohibit anyone from knowingly and willingly presenting, or causing to be
presented for payment to third party payors (including Medicare and Medicaid) claims for reimbursement or services that are false
or fraudulent, claims for items or services not provided as claimed, or claims for medically unnecessary items or services. The
sunshine provisions apply to manufacturers with products reimbursed under certain government programs and require those manufacturers
to disclose annually to the federal government certain payments made to physicians (defined to include doctors, dentists, optometrists,
podiatrists and chiropractors) and teaching hospitals, as well as, ownership and investment interests held by physicians (as defined
above) and their immediate family members. State laws may also require disclosure of pharmaceutical pricing information and marketing
expenditures. Although we seek to comply with these statutes, it is possible that our practices, or those of our partners, might
be challenged under health care fraud and abuse, anti-kickback, false claims or similar laws. Violations of the physician sunshine
act and similar state legislation or the fraud and abuse laws may be punishable by civil or criminal sanctions, including fines
and civil monetary penalties, and future exclusion from participation in government healthcare programs. &nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
have a number of outstanding post-marketing commitments to the FDA that we retain, despite our partnership with SUL, which we
may not complete successfully or on time for any number of reasons, including but not limited to lack of funds to complete the
studies and insufficient interest by appropriate sites, investigators or study subjects. For example, as a condition of the approval
of RAPIVAB, we are required to complete a pediatric patient study of RAPIVAB and to submit the final results of this clinical
trial to the FDA. Depending on the outcome of this clinical trial, we may be unable to expand the indication for RAPIVAB or we
may be required to include specific warnings or limitations on dosing this product, which could negatively impact sales of RAPIVAB
and negatively impact our relationship with our partner. We may be subject to penalties if we fail to comply with post-approval
legal and regulatory requirements and our products could be subject to continual recordkeeping and reporting requirements, review
and periodic inspections by the FDA and other regulatory bodies. Regulatory approval of a product may be subject to limitations
on the indicated uses for which the product may be marketed or to the other restrictive conditions of approval that limit our
ability to promote, sell or distribute a product. Furthermore, the approval of RAPIVAB and any other future product candidates
may be subject to requirements for costly post-marketing testing and surveillance to monitor its safety or efficacy.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Advertising
and promotion are subject to stringent FDA rules and oversight and as the holder of the NDA we may be held responsible for any
advertising and promotion conducted by our partner that is not in compliance with the rules and regulations. In particular, the
claims in all promotional materials and activities must be consistent with the FDA approvals for approved products, and must be
appropriately substantiated and fairly balanced with information on the safety risks and limitations of the products. Adverse
event information concerning approved products must be reviewed and as the NDA holder of RAPIVAB we are required to make expedited
and periodic adverse event reports to the FDA and other regulatory authorities.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
addition, the research, manufacturing, distribution, sale and promotion of products are potentially subject to regulation by various
federal, state and local authorities in addition to the FDA, including the Centers for Medicare and Medicaid Services, other divisions
of the U.S. Department of Health and Human Services, the U.S. Department of Justice and individual U.S. Attorney offices within
the Department of Justice, and state and local governments. Until we can successfully transfer the pricing responsibilities to
our partner, we remain responsible for pricing and rebate programs. Pricing and rebate programs must comply with the Medicaid
rebate requirements of the Omnibus Budget Reconciliation Act of 1990, as amended, and the Veterans Health Care Act of 1992, as
amended. If products are made available to authorized users of the Federal Supply Schedule of the General Services Administration,
additional laws and requirements apply. All of these activities are also potentially subject to federal and state healthcare false
claims and fraud and abuse laws, as well as consumer protection and unfair competition laws.&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If
our operations with respect to RAPIVAB or our other products that are subject to healthcare laws and regulations are found to
be in violation of any of the healthcare fraud and abuse laws described above or any other governmental regulations that apply
to us, we may be subject to penalties, including civil and criminal penalties, damages, fines and the curtailment or restructuring
of our operations. Any penalties, damages, fines, curtailment or restructuring of our operations could adversely affect our ability
to operate our business and our financial results. Although compliance programs can mitigate the risk of investigation and prosecution
for violations of these laws, the risks cannot be entirely eliminated. Any action against us for violation of these laws, even
if we successfully defend against it, could cause us to incur significant legal expenses and divert our management's attention
from the operation of our business. Moreover, achieving and sustaining compliance with all applicable federal and state fraud
and abuse laws may be costly.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
and our partners may be subject to new legislation, regulatory proposals and healthcare payor initiatives that may increase our
costs of compliance and adversely affect our or our partners&rsquo; ability to market our products, including RAPIVAB, obtain
collaborators and raise capital.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
Patient Protection and Affordable Care Act, or PPACA, made extensive changes to the delivery of health care in the U.S. The PPACA
included numerous provisions that affect pharmaceutical companies, some of which became effective immediately and others of which
have taken effect over the past several years. For example, the PPACA expanded health care coverage to the uninsured through private
health insurance reforms and an expansion of Medicaid. The PPACA also imposed substantial costs on pharmaceutical manufacturers,
such as an increase in liability for rebates paid to Medicaid, new drug discounts that must be offered to certain enrollees in
the Medicare prescription drug benefit, an annual fee imposed on all manufacturers of brand prescription drugs in the U.S., and
an expansion of an existing program requiring pharmaceutical discounts to certain types of hospitals and federally subsidized
clinics. The PPACA also contains cost containment measures that could reduce reimbursement levels for health care items and services
generally, including pharmaceuticals. It also required reporting and public disclosure of payments and other transfers of value
provided by pharmaceutical companies to physicians and teaching hospitals.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
expect that the current presidential administration and U.S. Congress will seek to modify, repeal, or otherwise invalidate all,
or certain provisions of, the PPACA. There is still significant uncertainty with respect to the impact that the current presidential
administration and the U.S. Congress may have on the PPACA, if any, and any changes will likely take time to unfold. As such,
we cannot predict what effect the PPACA or other healthcare reform initiatives that may be adopted in the future will have on
our business.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
continuing efforts of the government, insurance companies, managed care organizations and other payors of health care services
to contain or reduce costs of health care could result in decreased net revenues from our pharmaceutical products and decrease
potential returns from our development efforts. In addition, pharmaceutical and device manufacturers are also required to report
and disclose certain payments and transfers of value to, and investment interests held by, physicians and their immediate family
members during the preceding calendar year. &nbsp;Failure to submit required information may result in civil monetary penalties
for payments, transfers of value or ownership or investment interests not reported in an annual submission. Compliance with the
PPACA and state laws with similar provisions is difficult and time consuming, and companies that do not comply with these state
laws face civil penalties. Because of the breadth of these laws and the narrowness of the safe harbors, it is possible that some
of our business activities could be subject to challenge under one or more of such laws. Such a challenge could have a material
adverse effect on our business, financial condition, results of operations and growth prospects.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
addition, there have been a number of other legislative and regulatory proposals aimed at changing the pharmaceutical industry.
In particular, legislation has been enacted in certain states and at a federal level that requires development of an electronic
pedigree to track and trace each prescription drug at the saleable unit level through the distribution system. Compliance with
these electronic pedigree requirements may increase our operational expenses and impose significant administrative burdens. In
addition, our compliance may be deemed insufficient and we could face a material adverse effect on our business, financial condition,
results of operations and growth prospects.&nbsp; As a result of these and other new proposals, we may determine to change our
current manner of operation, provide additional benefits or change our contract arrangements, any of which could have a material
adverse effect on our business, financial condition and results of operations.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Adequate
coverage and reimbursement is critical to the commercial success of RAPIVAB or any other product that we might bring to market.
Recently there has been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed
products, which has resulted in several Congressional inquiries and proposed bills designed to, among other things, reform government
program reimbursement methodologies. Third-party payors are increasingly challenging the prices charged for medical products and
services and, in some cases, imposing restrictions on the coverage of particular drugs. Many third-party payors negotiate the
price of medical services and products and develop formularies which establish pricing and reimbursement levels. Exclusion of
a product from a formulary can lead to its sharply reduced usage in the third-party payor&rsquo;s patient population. The process
for obtaining coverage can be lengthy and costly, and we expect that it could take several months before a particular payor initially
reviews our product and makes a decision with respect to coverage. For example, third-party payors may require cost-benefit analysis
data from us in order to demonstrate the cost-effectiveness of RAPIVAB or any other product we might bring to market. For any
individual third-party payor, we may not be able to provide data sufficient to gain reimbursement on a similar or preferred basis
to competitive products, or at all which may have a material adverse effect on our business, financial condition and results of
operations.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>There
are risks related to the potential government use or sale of peramivir (RAPIVAB).</I></B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 27pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">United
States Government use or sale of RAPIVAB in emergency situations, or otherwise, may result in the use of RAPIVAB outside of its
approved use. To the extent that RAPIVAB is used as a treatment for influenza by the U.S. Government or peramivir by any other
government entity, there can be no assurance that it will prove to be generally safe, well-tolerated and effective. Such government
use of RAPIVAB/peramivir may create certain liabilities for us or our partners in the case of government use outside of the U.S.
There is no assurance that we or our manufacturers will be able to fully meet the demand for peramivir in the event of additional
orders. Further, we may not achieve a favorable price for additional orders of RAPIVAB in the U.S. or peramivir in any other country.
Our competitors may develop products that could compete with or replace peramivir . We may face competition in markets where we
have no existing intellectual property protection or are unable to successfully enforce our intellectual property rights.</FONT></P>

<P STYLE="font-size: 10pt; text-align: justify; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">There
is no assurance that the non-U.S. partnerships that we have entered into for peramivir will result in any order for peramivir
in those countries. There is no assurance that peramivir will be approved for any use or will achieve market approval in additional
countries. In the event that any emergency use or market approval is granted, there is no assurance that any government order
or commercialization of peramivir in any countries will be substantial or will be profitable to us. In addition, the sale of peramivir
, emergency use or other use of peramivir in any country may create certain liabilities for us and our partners.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>If
we or our partners do not obtain and maintain governmental approvals for our product candidates under development, we or our partners
will not be able to sell these potential products, which would significantly harm our business because we will receive no revenue.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
or our partners must obtain regulatory approval before marketing or selling our future product candidates. If we or our partners
are unable to receive regulatory approval and do not market or sell our future product candidates, we will never receive any revenue
from such product sales. In the United States, we or our partners must obtain FDA approval for product candidates that we intend
to commercialize. The process of preparing for and obtaining FDA approval may be lengthy and expensive, and approval is never
certain. Products distributed abroad are also subject to foreign government regulation and export laws of the United States. Because
of the risks and uncertainties in biopharmaceutical development, our product candidates could take a significantly longer time
to gain regulatory approval than we expect or may never gain approval. If the FDA delays regulatory approval of our product candidates,
our management&rsquo;s credibility, our value and our operating results may suffer. Even if the FDA or foreign regulatory agencies
approve a product candidate, the approval may limit the indicated uses for a product candidate and/or may require post-approval
studies.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
FDA regulates, among other things, the record keeping and storage of data pertaining to potential pharmaceutical products. We
currently store most of our preclinical research data, our clinical data and our manufacturing data at our facility. While we
do store duplicate copies of most of our clinical data offsite and a significant portion of our data is included in regular backups
of our systems, we could lose important data if our facility incurs damage, or if our vendor data systems fail, suffer damage
or are destroyed. If we receive approval to market our potential products, whether in the United States or internationally, we
will continue to be subject to extensive regulatory requirements. These requirements are wide ranging and govern, among other
things:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">adverse
                                         drug experience reporting regulations;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">product
                                         promotion;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">product
                                         manufacturing, including good manufacturing practice requirements; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">product
                                         changes or modifications.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
failure to comply with existing or future regulatory requirements, or our loss of, or changes to, previously obtained approvals,
could have a material adverse effect on our business because we will not receive product or royalty revenues if we or our partners
do not receive approval of our products for marketing.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Royalties
and milestone payments from Shionogi under our license agreement with Shionogi (the &ldquo;Shionogi Agreement&rdquo;) will be
required to be used by Royalty Sub to service its obligations under its PhaRMA Notes, and generally will not be available to us
for other purposes until Royalty Sub has repaid in full its obligations under the PhaRMA Notes.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
March 2011, our wholly-owned subsidiary Royalty Sub issued $30.0 million in aggregate principal amount of PhaRMA Notes. The PhaRMA
Notes are secured principally by (i) certain royalty and milestone payments under the Shionogi Agreement, pursuant to which Shionogi
licensed from us the rights to market peramivir in Japan and Taiwan, (ii) rights to certain payments under a Japanese yen/U.S.
dollar foreign currency hedge arrangement put into place by us in connection with the issuance of the PhaRMA Notes and (iii) the
pledge by us of our equity interest in Royalty Sub. Payments from Shionogi to us under the Shionogi Agreement will generally not
be available to us for other purposes until Royalty Sub has repaid in full its obligations under the PhaRMA Notes. Accordingly,
these funds will be required to be dedicated to Royalty Sub&rsquo;s debt service and not available to us for product development
or other purposes. As of September 1, 2014, the payments from Shionogi were insufficient for Royalty Sub to service its obligations
under the PhaRMA Notes, resulting in an event of default with respect to the PhaRMA Notes. As a result of this event of default,
the holders of the PhaRMA Notes may be able to pursue acceleration of the PhaRMA Notes and foreclose on the collateral securing
the PhaRMA Notes and our equity interest in Royalty Sub and may&nbsp;exercise other remedies available to them under the indenture
or other documents related to&nbsp;the PhaRMA Notes. In such event, we may not realize the benefit of future royalty payments
that might otherwise accrue to us following repayment of the PhaRMA Notes, we may incur legal costs&nbsp;and we might otherwise
be adversely affected.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Because
an event of default has occurred under the PhaRMA Notes, the holders of the PhaRMA Notes may be able to pursue acceleration of
the PhaRMA Notes and foreclose on the collateral securing the PhaRMA Notes and our equity interest in Royalty Sub, in which case
we may not realize the benefit of future royalty payments that might otherwise accrue to us following repayment of the PhaRMA
Notes and we could otherwise be adversely affected.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Royalty
Sub&rsquo;s ability to service its payment obligations in respect of the PhaRMA Notes, and our ability to benefit from our equity
interest in Royalty Sub, is subject to numerous risks. Royalty Sub&rsquo;s ability to service the PhaRMA Notes may be adversely
affected by, among other things, changes in or any termination of our relationship with Shionogi, reimbursement, regulatory, manufacturing
and/or intellectual property issues, product returns, product recalls, product liability claims and allegations of safety issues,
as well as other factors. As Royalty Sub has been unable to service its obligations under the PhaRMA Notes and an event of default
has occurred under the PhaRMA Notes, the holders of the PhaRMA Notes may be able to pursue acceleration of the PhaRMA Notes and
foreclose on the collateral securing the PhaRMA Notes and our equity interest in Royalty Sub and may&nbsp;exercise other remedies
available to them under the indenture&nbsp;or other documents related to&nbsp;the PhaRMA Notes. In such event, we may not realize
the benefit of future royalty payments that might otherwise accrue to us following repayment of the PhaRMA Notes, we may incur
legal costs&nbsp;and we might otherwise be adversely affected.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
may be required to pay significant premiums under the foreign currency hedge arrangement entered into by us in connection with
the issuance of the PhaRMA Notes. In addition, because our potential obligations under the foreign currency hedge are marked to
market, we may experience additional quarterly volatility in our operating results and cash flows attributable to the foreign
currency hedge arrangement.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
connection with the issuance by Royalty Sub of the PhaRMA Notes, we entered into a foreign currency hedge arrangement to hedge
certain risks associated with changes in the value of the Japanese yen relative to the U.S. dollar. Under the foreign currency
hedge agreement, we may be required to pay an annual premium in the amount of $2.0 million in each May continuing through May
2020. Such payment will be required if, in May of the relevant year, the spot rate of exchange for Japanese yen-U.S. dollars (determined
in accordance with the foreign currency hedge arrangement) is such that the U.S. dollar is worth 100 yen or less. We will be required
to mark-to-market our potential obligations under the currency hedge and post cash collateral, which may cause us to experience
additional quarterly volatility in our operating results and cash flows as a result. Additionally, we may be required to pay significant
premiums or a termination fee under the foreign currency hedge agreement entered into by us in connection with the issuance of
the PhaRMA Notes. We are required to maintain a foreign currency hedge at 100 yen per dollar under the agreements governing the
PhaRMA Notes.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Our
Senior Credit Facility contains restrictions that limit our flexibility in operating our business. We may be required to make
a prepayment or repay the outstanding indebtedness earlier than we expect if a prepayment event or an event of default occurs,
including a material adverse change with respect to us, which could have a material adverse effect on our business.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
Senior Credit Facility contains various covenants that limit our ability to engage in specified types of transactions. These covenants
limit our ability to, among other things:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">convey,
                                         sell, lease, license, transfer or otherwise dispose of certain parts of our business
                                         or property;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">change
                                         the nature of our business;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">liquidate
                                         or dissolve;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">enter
                                         into certain change in control or acquisition transactions;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">incur
                                         or assume certain debt;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">grant
                                         certain types of liens on our assets;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">modify,
                                         liquidate or transfer assets in certain collateral accounts;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">pay
                                         dividends or make certain distributions to our stockholders;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">make
                                         certain investments;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">enter
                                         into material transactions with affiliates; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">modify
                                         existing debt or collaboration arrangements.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

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<P STYLE="margin-top: 0; margin-bottom: 0"></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
restrictive covenants contained in the Senior Credit Facility could cause us to be unable to pursue business opportunities that
we or our stockholders may consider beneficial without the lender&rsquo;s permission or without repaying all Senior Credit Facility
obligations.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">A
breach of any of these covenants could result in an event of default under the Senior Credit Facility. An event of default will
also occur if, among other things, a material adverse change in our business, operations or condition occurs, which could potentially
include negative results in clinical trials, or a material impairment of the prospect of our repayment of any portion of the amounts
we owe under the Senior Credit Facility occurs. In the case of a continuing event of default under the agreement, the lender could
elect to declare all amounts outstanding to be immediately due and payable, proceed against the collateral in which we granted
to the lender a security interest under the Senior Credit Facility, or otherwise exercise the rights of a secured creditor. Amounts
outstanding under the Senior Credit Facility are secured by substantially all of our assets and those of our subsidiaries, excluding
certain specified assets but including proceeds from those assets.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>If
we fail to adequately protect or enforce our intellectual property rights or secure rights to patents of others, the value of
those rights would diminish.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
success will depend in part on our ability and the abilities of our partners to obtain, protect and enforce viable intellectual
property rights including but not limited to trade name, trademark and patent protection for our Company and its products, methods,
processes and other technologies we may license or develop, to preserve our trade secrets, and to operate without infringing the
proprietary rights of third parties both domestically and abroad. The patent position of biotechnology and pharmaceutical companies
is generally highly uncertain, involves complex legal and factual questions and has recently been the subject of much litigation.
Neither the United States Patent and Trademark Office (&ldquo;USPTO&rdquo;), the Patent Cooperation Treaty offices, nor the courts
of the United States and other jurisdictions have consistent policies nor predictable rulings regarding the breadth of claims
allowed or the degree of protection afforded under many biotechnology and pharmaceutical patents. Further, we may not have worldwide
patent protection for all of our product candidates and our intellectual property rights may not be legally protected or enforceable
in all countries throughout the world. In some jurisdictions, some of our product candidates in certain programs, including our
HAE program, may have short or no composition of matter patent life and we may therefore rely on orphan drug exclusivity or data
exclusivity. There can be no assurance that we will obtain orphan drug exclusivity or data exclusivity in every jurisdiction.
Further, in some jurisdictions, we may rely on formulation patents or method of use patents. Both the ability to achieve issuance
and the enforcement of formulation and method of use patents can be highly uncertain and can vary from jurisdiction to jurisdiction,
and such patents may therefore not adequately prevent competitors and potential infringers in some jurisdictions. The validity,
scope, enforceability and commercial value of the rights protected by such patents, therefore, is highly uncertain.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
also rely on trade secrets to protect technology in cases when we believe patent protection is not appropriate or obtainable.
However, trade secrets are difficult to protect. If we cannot maintain the confidentiality of our technology and other confidential
information in connection with our collaborators and advisors, our ability to receive patent protection or protect our proprietary
information may be imperiled.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
may be involved in lawsuits to protect or enforce our patents, the patents of our partners or our other intellectual property
rights, which could be expensive, time consuming and unsuccessful.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Competitors
may infringe or otherwise violate our patents, the patents of our licensors or our other intellectual property rights. To counter
infringement or unauthorized use, we may be required to file legal claims, which can be expensive and time-consuming and unsuccessful.
An adverse result in any litigation or defense proceeding could put one or more of our patents at risk. Our success depends in
part on avoiding the infringement of other parties&rsquo; patents and other intellectual property rights as well as avoiding the
breach of any licenses relating to our technologies and products. In the United States, patent applications filed in recent years
are confidential for 18 months, while older applications are not published until the patent issues. As a result, avoiding patent
infringement may be difficult and we may inadvertently infringe third-party patents or proprietary rights. These third parties
could bring claims against us, our partners or our licensors that even if resolved in our favor, could cause us to incur substantial
expenses and, if resolved against us, could additionally cause us to pay substantial damages. Further, if a patent infringement
suit were brought against us, our partners or our licensors, we or they could be forced to stop or delay research, development,
manufacturing or sales of any infringing product in the country or countries covered by the patent we infringe, unless we can
obtain a license from the patent holder. Such a license may not be available on acceptable terms, or at all, particularly if the
third party is developing or marketing a product competitive with the infringing product. Even if we, our partners or our licensors
were able to obtain a license, the rights may be nonexclusive, which would give our competitors access to the same intellectual
property.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If
we or our partners are unable or fail to adequately initiate, protect, defend or enforce our intellectual property rights in any
area of commercial interest or in any part of the world where we wish to seek regulatory approval for our products, methods, processes
and other technologies, the value of the product candidates to produce revenue would diminish. Additionally, if our products,
methods, processes, and other technologies or our commercial use of such products, processes, and other technologies, including
but not limited to any trade name, trademark or commercial strategy infringe the proprietary rights of other parties, we could
incur substantial costs. The USPTO and the patent offices of other jurisdictions have issued to us a number of patents for our
various inventions and we have in-licensed several patents from various institutions. We have filed additional patent applications
and provisional patent applications with the USPTO. We have filed a number of corresponding foreign patent applications and intend
to file additional foreign and U.S. patent applications, as appropriate. We have also filed certain trademark and trade name applications
worldwide. We cannot assure you as to:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         degree and range of protection any patents will afford against competitors with similar
                                         products;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">if
                                         and when patents will issue;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">if
                                         patents do issue we cannot be sure that we will be able to adequately defend such patents
                                         and whether or not we will be able to adequately enforce such patents; or</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">whether
                                         or not others will obtain patents claiming aspects similar to those covered by our patent
                                         applications.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If
the USPTO or other foreign patent office upholds patents issued to others or if the USPTO grants patent applications filed by
others, we may have to:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">obtain
                                         licenses or redesign our products or processes to avoid infringement;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">stop
                                         using the subject matter claimed in those patents; or</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">pay
                                         damages.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
may initiate, or others may bring against us, litigation or administrative proceedings related to intellectual property rights,
including proceedings before the USPTO or other foreign patent office. Any judgment adverse to us in any litigation or other proceeding
arising in connection with a patent or patent application could materially and adversely affect our business, financial condition
and results of operations. In addition, the costs of any such proceeding may be substantial whether or not we are successful.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
success is also dependent upon the skills, knowledge and experience, none of which is patentable, of our scientific and technical
personnel. To help protect our rights, we require all employees, consultants, advisors and partners to enter into confidentiality
agreements that prohibit the disclosure of confidential information to anyone outside of our company and require disclosure and
assignment to us of their ideas, developments, discoveries and inventions. These agreements may not provide adequate protection
for our trade secrets, know-how or other proprietary information in the event of any unauthorized use or disclosure or the lawful
development by others of such information, and if any of our proprietary information is disclosed, our business will suffer because
our revenues depend upon our ability to license or commercialize our product candidates and any such events would significantly
impair the value of such product candidates.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Our
failure to comply with data protection laws and regulations could lead to government enforcement actions and significant penalties
against us and adversely impact our operating results.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">European
Union (&ldquo;EU&rdquo;) Member States, Switzerland and other countries have adopted data protection laws and regulation, which
impose significant compliance obligations.&nbsp;For example, the EU Data Protection Directive, as implemented into national laws
by the EU Member States, imposes strict obligations and restrictions on the ability to collect, analyze and transfer personal
data, including health data from clinical trials and adverse event reporting.&nbsp;Data protection authorities from the different
EU Member States may interpret the EU Data Protection Directive and national laws differently, which adds to the complexity of
processing personal data in the European Union, and guidance on implementation and compliance practices is often updated or otherwise
revised.&nbsp;Our failure to comply with these laws and regulations could lead to government enforcement actions and significant
penalties against us, and adversely impact our operating results.&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
are subject to periodic litigation, which could result in losses or unexpected expenditure of time and resources.&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">From
time to time, we may be called upon to defend ourselves against lawsuits relating to our business.&nbsp; Due to the inherent uncertainties
in litigation, we cannot accurately predict the ultimate outcome of any such proceedings.&nbsp; An unfavorable outcome in any
such proceedings could have an adverse impact on our business, financial condition and results of operations.&nbsp;If our stock
price is volatile, we may become involved in securities class action lawsuits in the future.&nbsp;Any litigation in the future,
regardless of its merits, could result in substantial costs and a diversion of management&rsquo;s attention and resources that
are needed to successfully run our business.&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><B><I>We
face an inherent risk of liability in the event that the use or misuse of our products results in personal injury or death and
our product liability insurance coverage may be insufficient.</I></B></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If
the use or misuse of peramivir or any other regulatory body-approved products we or a partner may sell in the future harms people,
we may be subject to costly and damaging product liability claims brought against us by consumers, healthcare providers, pharmaceutical
companies, third-party payors or others. The use of our product candidates in clinical trials, including post marketing clinical
studies, could also expose us to product liability claims. We cannot predict all of the possible harms or side effects that may
result from the use of our products or the testing of product candidates and, therefore, the amount of insurance coverage we currently
may not be adequate to cover all liabilities or defense costs we might incur. A product liability claim or series of claims brought
against us could give rise to a substantial liability that could exceed our resources. Even if claims are not successful, the
costs of defending such claims and potential adverse publicity could be harmful to our business.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
face an inherent risk of product liability exposure related to the testing of our product candidates in human clinical trials
and will face even greater risks upon any commercialization by us of our product candidates. We have product liability insurance
covering our commercial sale of peramivir and our clinical trials. Clinical trial and product liability insurance is becoming
increasingly expensive. As a result, we may be unable to obtain sufficient insurance or increase our existing coverage at a reasonable
cost to protect us against losses that could have a material adverse effect on our business. An individual may bring a product
liability claim against us if one of our products or product candidates causes, or is claimed to have caused, an injury or is
found to be unsuitable for consumer use. Any product liability claim brought against us, with or without merit, could result in:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">liabilities
                                         that substantially exceed our product liability insurance, which we would then be required
                                         to pay from other sources, if available;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">an
                                         increase of our product liability insurance rates or the inability to maintain insurance
                                         coverage in the future on acceptable terms, or at all;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">withdrawal
                                         of clinical trial volunteers or patients;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">damage
                                         to our reputation and the reputation of our products, resulting in lower sales;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">regulatory
                                         investigations that could require costly recalls or product modifications;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">litigation
                                         costs; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         diversion of management&rsquo;s attention from managing our business.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Insurance
coverage is increasingly more costly and difficult to obtain or maintain.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">While
we currently have insurance for our business, property, directors and officers, and our products, insurance is increasingly more
costly and narrower in scope, and we may be required to assume more risk in the future. If we are subject to claims or suffer
a loss or damage in excess of our insurance coverage, we will be required to bear any loss in excess of our insurance limits.
If we are subject to claims or suffer a loss or damage that is outside of our insurance coverage, we may incur significant uninsured
costs associated with loss or damage that could have an adverse effect on our operations and financial position. Furthermore,
any claims made on our insurance policies may impact our ability to obtain or maintain insurance coverage at reasonable costs
or at all.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>If
our facility incurs damage or power is lost for a significant length of time, our business will suffer.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
store clinical and stability samples at our facility that could be damaged if our facility incurs physical damage or in the event
of an extended power failure. We have backup power systems in addition to backup generators to maintain power to all critical
functions, but any loss of these samples could result in significant delays in our drug development process.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
addition, we store most of our preclinical and clinical data at our facilities. Duplicate copies of most critical data are secured
off-site. Any significant degradation or failure of our computer systems could cause us to inaccurately calculate or lose our
data. Loss of data could result in significant delays in our drug development process and any system failure could harm our business
and operations.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>A
significant disruption in our information technology systems or a cyber-security breach could adversely affect our business.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
are increasingly dependent on information technology systems to operate our business. Like other companies in our industry, our
networks and infrastructure may be vulnerable to cyber-attacks or intrusions, including by computer hackers, foreign governments,
foreign companies or competitors, or may be breached by employee error, malfeasance or other disruption. A breakdown, invasion,
corruption, destruction or interruption of critical information technology systems could negatively impact operations.&nbsp; If
our systems are damaged, fail to function properly or otherwise become unavailable, we may incur substantial costs to repair or
replace them, and we may experience loss of critical data and interruptions or delays in our ability to perform critical functions,
which could adversely affect our business, financial condition or results of operations. Any compromise of our data security could
also result in a violation of applicable privacy and other laws, significant legal and financial exposure, damage to our reputation,
loss or misuse of the information and a loss of confidence in our data security measures, which could harm our business. There
can be no assurance that our efforts to protect our data and information technology systems will prevent breakdowns or breaches
in our systems, or those of third parties with which we do business, and any such events could adversely affect our business.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>If
we fail to retain our existing key personnel or fail to attract and retain additional key personnel, the development of our product
candidates and commercialization of our products and the related expansion of our business will be delayed or stopped.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
are highly dependent upon our senior management and scientific team, the unexpected loss of whose services might impede the achievement
of our development and commercial objectives. Competition for key personnel with the experience that we require is intense and
is expected to continue to increase. Our inability to attract and retain the required number of skilled and experienced management,
commercial, operational and scientific personnel will harm our business because we rely upon these personnel for many critical
functions of our business.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>If
because of our use of hazardous materials, we violate any environmental controls or regulations that apply to such materials,
we may incur substantial costs and expenses in our remediation efforts.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
research and development involves the controlled use of hazardous materials, chemicals and various radioactive compounds. We are
subject to federal, state and local laws and regulations governing the use, storage, handling and disposal of these materials
and some waste products. Accidental contamination or injury from these materials could occur. In the event of an accident, we
could be liable for any damages that result and any liabilities could exceed our resources. Compliance with environmental laws
and regulations or a violation of such environmental laws and regulations could require us to incur substantial unexpected costs,
which would materially and adversely affect our results of operations.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Risks
relating to investing in our common stock</B></FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>&nbsp;</B></FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Our
existing principal stockholders hold a substantial amount of our common stock and may be able to influence significant corporate
decisions, which may conflict with the interest of other stockholders.</I></B></FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Several
of our stockholders own greater than 5% of our outstanding common stock. Our top ten stockholders own more than 50% of BioCryst
and can individually, and as a group, influence our operations based upon their concentrated ownership. These stockholders, if
they act together, may be able to influence the outcome of matters requiring approval of the stockholders, including the election
of our directors and other corporate actions.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Our
stock price has been, and is likely to continue to be, highly volatile, which could cause the value of an investment in our common
stock to decline significantly.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">The
market prices for securities of biotechnology companies in general have been highly volatile and may continue to be highly volatile
in the future. Moreover, our stock price has fluctuated frequently, and these fluctuations are often not related to our financial
results. For the twelve months ended December 31, 2016, the 52-week range of the market price of our stock was from $</FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">1.63
to $10.24 per share. The following factors, in addition to other risk factors described in this section, may have a significant
impact on the market price of our common stock:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">announcements
                                         of technological innovations or new products by us or our competitors;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">developments
                                         or disputes concerning patents or proprietary rights;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">additional
                                         dilution through sales of our common stock or other derivative securities;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">status
                                         of new or existing licensing or collaborative agreements and government contracts;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">announcements
                                         relating to the status of our programs;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">developments
                                         and announcements regarding new and virulent strains of influenza;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">we
                                         or our partners achieving or failing to achieve development milestones;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">publicity
                                         regarding actual or potential medical results relating to products under development
                                         by us or our competitors;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">publicity
                                         regarding certain public health concerns for which we are or may be developing treatments;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">regulatory
                                         developments in both the United States and foreign countries;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">public
                                         concern as to the safety of pharmaceutical products;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">actual
                                         or anticipated fluctuations in our operating results;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">changes
                                         in financial estimates or recommendations by securities analysts;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">changes
                                         in the structure of healthcare payment systems, including developments in price control
                                         legislation;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">announcements
                                         by us or our competitors of significant acquisitions, strategic partnerships, joint ventures
                                         or capital commitments;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">additions
                                         or departures of key personnel or members of our board of directors;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">purchases
                                         or sales of substantial amounts of our stock by existing stockholders, including officers
                                         or directors;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

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<P STYLE="margin-top: 0; margin-bottom: 0"></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">economic
                                         and other external factors or other disasters or crises; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">period-to-period
                                         fluctuations in our financial results.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>Future
sales and issuances of securities may dilute your ownership interest and cause our stock price to decline.</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0">Future sales of our common stock by current stockholders into the public market could cause the market price
of our stock to fall. As of March 7, 2017, there were 74,019,280 shares of our common stock outstanding. We may from time to time
issue securities in relation to a license arrangement, collaboration, merger or acquisition. We may also sell, for our own account,
shares of common stock or other equity securities, from time to time at prices and on terms to be determined at the time of sale.</P>



<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font: 10pt Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">As
of February 28, 2017, there were 14,127,277 stock options and restricted stock units outstanding, </FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">458,478
shares available for issuance under our Amended and Restated Stock Incentive Plan, and 363,646 shares available for issuance
under our Employee Stock Purchase Plan. In addition, we could also make equity compensation grants outside of our Stock
Incentive Plan. The shares underlying existing stock options, restricted stock units and possible future stock options, stock
appreciation rights and stock awards have been registered pursuant to registration statements on Form S-8.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If
some or all of such shares are sold or otherwise issued into the public market over a short period of time, our current stockholders&rsquo;
ownership interests may be diluted and the value of all publicly traded shares is likely to decline, as the market may not be
able to absorb those shares at then-current market prices. Additionally, such sales and issuances may make it more difficult for
us to sell equity securities or equity-related securities in the future at a time and price that our management deems acceptable,
or at all.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0">We anticipate entering into a Registration Rights Agreement with entities affiliated
with Baker Bros. Advisors LP (the &ldquo;Baker Entities&rdquo;) to provide that, if requested, we will register the shares of our
common stock beneficially owned by the Baker Entities for resale under the Securities Act. Our registration obligations, as proposed,
are expected to cover all shares now held or hereafter acquired by the Baker Entities, to be in effect for up to ten years, and
to include our obligation to facilitate certain underwritten public offerings of our common stock by the Baker Entities in the
future. If the Baker Entities, by exercising these registration and/or underwriting rights or otherwise, sell a large number of
our shares, or the market perceives that the Baker Entities intend to sell a large number of our shares, this could adversely affect
the market price of our common stock.</P>



<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
have anti-takeover provisions in our corporate charter documents that may result in outcomes with which you do not agree.</I></B></FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
board of directors has the authority to issue up to 4,800,000 shares of undesignated preferred stock and to determine the rights,
preferences, privileges and restrictions of those shares without further vote or action by our stockholders. The rights of the
holders of any preferred stock that may be issued in the future may adversely affect the rights of the holders of common stock.
The issuance of preferred stock could make it more difficult for third parties to acquire a majority of our outstanding voting
stock.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
addition, our certificate of incorporation provides for staggered terms for the members of the board of directors and supermajority
approval of the removal of any member of the board of directors and prevents our stockholders from acting by written consent.
Our certificate also requires supermajority approval of any amendment of these provisions. These provisions and other provisions
of our by-laws and of Delaware law applicable to us could delay or make more difficult a merger, tender offer or proxy contest
involving us.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
have broad discretion in the use of the net proceeds from this offering and may not use them effectively.</I></B></FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Management
will have broad discretion in the application of the net proceeds, including any of the purposes described in &ldquo;Use of Proceeds.&rdquo;
The failure by our management to apply these funds effectively could have a material adverse effect on our business.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>We
have never paid dividends on our common stock and do not anticipate doing so in the foreseeable future.</I></B></FONT></P>

<P STYLE="font-size: 10pt; font-style: italic; font-weight: bold; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B><I>&nbsp;</I></B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
have never paid cash dividends on our stock. We currently intend to retain all future earnings, if any, for use in the operation
of our business. Accordingly, we do not anticipate paying cash dividends on our common stock in the foreseeable future.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 16pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; text-transform: none"><B>Use
of proceeds</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0">We estimate that we will receive net proceeds of approximately $41.9 million from the
sale of shares of our common stock offered by us in this offering, after deducting  underwriting discounts and commissions
and estimated offering expenses payable by us. If the underwriters exercise their option to purchase additional shares in full,
we estimate that the net proceeds to us will be approximately $48.1 million, after deducting  underwriting discounts and
commissions and estimated offering expenses payable by us. We intend to use the net proceeds from this offering for general corporate
purposes, including future clinical development of BCX7353, continued development of our second generation HAE compounds, including
for other indications, and the advancement of our other preclinical rare disease programs.</P>



<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font: 10pt Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
amount and timing of these expenditures will depend on a number of factors, including the progress of our research and development
efforts and amounts received under our existing and any future government contracts and collaboration arrangements, as well as
the amount of cash used in our operations. Accordingly, our management will have broad discretion in the application of these
proceeds, and investors will be relying on the judgment of our management with regard to the use of these proceeds. Pending application
of the net proceeds as described above, we intend to invest the proceeds in investment grade interest-bearing instruments.</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>&nbsp;</B></FONT></P>

<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 16pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; text-transform: none"><B>Dilution</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font: 10pt Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0">As of December 31, 2016, our net tangible book value was approximately $11.5 million,
or approximately $0.16 per share of common stock. Net tangible book value per share represents the amount of our total assets,
excluding deferred collaboration expenses, less total liabilities, excluding deferred collaboration revenues, divided by the 73,781,854
shares of our common stock outstanding as of December 31, 2016.</P>

<P STYLE="font-size: 10pt; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; margin: 0pt 0">Investors participating in this offering will incur immediate, substantial dilution. After giving effect to our
receipt of approximately $41.9 million of estimated net proceeds (after deducting  underwriting discounts and commissions
and estimated offering expenses payable by us) from our sale of common stock in this offering, our as adjusted net tangible book
value as of December 31, 2016 would have been $53.3 million, or $0.67 per share. This amount represents an immediate increase
in net tangible book value of $0.51 per share of our common stock to existing stockholders and an immediate dilution in net tangible
book value of $7.83 per share of our common stock to new investors purchasing shares of common stock in this offering.</P>



<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font: 10pt Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
following table illustrates this dilution on a per share basis:</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLSPACING="0" CELLPADDING="0" ALIGN="CENTER" STYLE="width: 80%; border-collapse: collapse; font-size: 10pt">
<TR STYLE="vertical-align: top; background-color: transparent">
    <TD STYLE="text-indent: -10pt; padding-left: 10pt; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">Public
    offering price per share&#9;</FONT></TD>
    <TD STYLE="border-top: Black 1.5pt solid; text-align: right; text-indent: 0in">&nbsp;</TD>
    <TD STYLE="border-top: Black 1.5pt solid; text-align: right; text-indent: 0in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.50</FONT></TD></TR>
<TR STYLE="vertical-align: top; background-color: transparent">
    <TD STYLE="text-indent: -10pt; padding-left: 10pt; width: 79%"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">Net
    tangible book value per share as of December 31, 2016&#9;</FONT></TD>
    <TD STYLE="text-align: right; width: 11%"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">$&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;0.16</FONT></TD>
    <TD STYLE="text-align: left; width: 10%">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top; background-color: transparent">
    <TD STYLE="text-indent: -10pt; padding-left: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">Increase
    in net tangible book value per share attributable to new investors&#9;</FONT></TD>
    <TD STYLE="text-decoration: none; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">$&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;0.51</FONT></TD>
    <TD STYLE="text-decoration: none; text-align: left">&nbsp;</TD></TR>
<TR STYLE="background-color: transparent">
    <TD STYLE="vertical-align: top; padding-left: 10pt; text-indent: -10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">Net
    tangible book value per share as of December 31, 2016 after giving effect to this offering&#9;</FONT></TD>
    <TD STYLE="vertical-align: bottom; text-decoration: none; text-indent: 0in; text-align: right">&nbsp;</TD>
    <TD STYLE="vertical-align: bottom; text-decoration: none; text-indent: 0in; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">$&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;0.67</FONT></TD></TR>
<TR STYLE="vertical-align: top; background-color: transparent">
    <TD STYLE="text-indent: -10pt; padding-left: 10pt; border-bottom: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">Dilution
    in net tangible book value per share to new investors&#9;</FONT></TD>
    <TD STYLE="border-bottom: Black 1.5pt solid; text-decoration: none; text-indent: 0in; text-align: right">&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1.5pt solid; text-decoration: none; text-indent: 0in; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">$&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.83</FONT></TD></TR>
</TABLE>
<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0">If the underwriters&rsquo; option to purchase additional shares is exercised in full, the as adjusted net
tangible book value per share after giving effect to this offering would be $0.75 per share, which amount represents an immediate
increase in as adjusted net tangible book value of $0.59 per share of our common stock to existing stockholders and an immediate
dilution in net tangible book value of $7.75 per share of our common stock to new investors purchasing shares of common stock
in this offering.</P>



<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font: 10pt Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">The
above discussion and table are based on </FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">73,781,854 shares of our
common stock outstanding as of December 31, 2016 and exclude:</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">12,094,470
                                         shares of common stock issuable upon the exercise of stock options outstanding under
                                         our Stock Incentive Plan as of December 31, 2016, at a weighted average exercise price
                                         of $6.55 per share;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">434,573
                                         shares of common stock issuable upon the vesting of restricted stock units outstanding
                                         under our Stock Incentive Plan as of December 31, 2016; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

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<P STYLE="margin-top: 0; margin-bottom: 0"></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">2,274,512
                                         additional shares of common stock reserved for issuance under our Stock Incentive Plan
                                         and 421,748 additional shares of common stock reserved for issuance under our Employee
                                         Stock Purchase Plan as of December 31, 2016.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">To
the extent that outstanding options have been or may be exercised or other shares issued, there may be further dilution to investors.
In addition, we may choose to raise additional capital due to market conditions or strategic considerations even if we believe
we have sufficient funds for our current or future operating plans. To the extent that we raise additional capital by issuing
equity securities or convertible debt, your ownership may be further diluted.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 16pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; text-transform: none"><B>Price
range of common stock and dividend policy</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
common stock is listed on the NASDAQ Global Select Market under the symbol &ldquo;BCRX.&rdquo; The following table sets forth,
for the periods indicated, the range of high and low sales prices for our common stock, as reported by the NASDAQ Global Select
Market.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="border-collapse: collapse; width: 100%">
<TR STYLE="vertical-align: bottom">
    <TD STYLE="font-size: 10pt; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; font-weight: bold; padding-bottom: 1pt; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="3" STYLE="font-size: 10pt; font-weight: bold; text-align: center; border-bottom: Black 1pt solid; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">High</FONT></TD><TD STYLE="font-size: 10pt; font-weight: bold; padding-bottom: 1pt; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD COLSPAN="3" STYLE="font-size: 10pt; font-weight: bold; text-align: center; border-bottom: Black 1pt solid; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Low</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt; font-weight: bold"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Year ended December
    31, 2015</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="width: 64%; font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">1<SUP>st
    </SUP>Quarter&#9;</FONT></TD><TD STYLE="width: 1%; font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 1%; font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="width: 15%; font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">12.71</FONT></TD><TD STYLE="width: 1%; font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="width: 1%; font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 1%; font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="width: 15%; font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">7.85</FONT></TD><TD STYLE="width: 1%; font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">2<SUP>nd</SUP> Quarter&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">16.43</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">8.50</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">3<SUP>rd</SUP> Quarter&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">16.83</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">10.26</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">4<SUP>th</SUP> Quarter&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">12.88</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">8.01</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt; font-weight: bold"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Year ended December
    31, 2016</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">1<SUP>st</SUP> Quarter&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">10.24</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">1.63</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">2<SUP>nd</SUP> Quarter&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">4.03</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">2.49</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">3<SUP>rd</SUP> Quarter&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">5.80</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">2.82</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">4<SUP>th</SUP> Quarter&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">7.56</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">3.75</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt; font-weight: bold"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Year ending December
    31, 2017</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">1<SUP>st</SUP> Quarter
    (through March 9</FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">, 2017)&#9;</FONT></TD><TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">8.86</FONT></TD><TD STYLE="font-size: 10pt; text-align: left; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT>$</TD><TD STYLE="font-size: 10pt; text-align: right; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">4.20</FONT></TD><TD STYLE="font-size: 10pt; text-align: left; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
</TABLE>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"></FONT></P>

<P STYLE="font-size: 10pt; text-align: left; margin: 0pt 0">The last reported sale price of our common stock on the NASDAQ Global Select Market on March 9, 2017 was $8.86
per share. As of March 7, 2017 there were approximately 182 holders of record of our common stock.</P>

<P STYLE="font-size: 10pt; text-align: justify; margin: 0pt 0">&nbsp;</P>



<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font: 10pt Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
have never paid cash dividends and do not anticipate paying cash dividends in the foreseeable future.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 16pt; text-transform: none"><B>Underwriting</B></FONT><B><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><SUP></SUP></FONT></B></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt; text-transform: none; color: blue; vertical-align: baseline"><B>&nbsp;</B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
are offering the shares of common stock described in this prospectus supplement through a number of underwriters. J.P. Morgan
Securities LLC is acting as sole book-running manager of the offering and as representative of the underwriters. We have entered
into an underwriting agreement with the underwriters. Subject to the terms and conditions of the underwriting agreement, we have
agreed to sell to the underwriters, and each underwriter has severally agreed to purchase, at the public offering price less the
underwriting discounts and commissions set forth on the cover page of this prospectus supplement, the number of shares of common
stock listed next to its name in the following table:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLSPACING="0" CELLPADDING="0" ALIGN="CENTER" STYLE="width: 90%; border-collapse: collapse; font-size: 10pt">
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="width: 83%; text-decoration: underline; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><B><U>Name</U></B></FONT></TD>
    <TD STYLE="width: 17%; text-align: center; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><B>Number
    of</B></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><BR>
    <FONT STYLE="font-size: 10pt"><B><U>Shares</U></B></FONT></FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">J.P. Morgan Securities LLC &#9;</FONT></TD>
    <TD STYLE="text-align: right">3,705,882</TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD>Piper Jaffray  &amp; Co. </TD>
    <TD STYLE="text-align: right">1,058,824 </TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD>JMP Securities LLC </TD>
    <TD STYLE="text-align: right; border-bottom: Black 1pt solid">529,412 </TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">Total&#9;</FONT></TD>
    <TD STYLE="border-bottom: Black 2.25pt double; text-align: right">5,294,118 </TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="text-align: right; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
</TABLE>
<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
underwriters are committed to purchase all the shares of common stock offered by us if they purchase any shares. The underwriting
agreement also provides that if an underwriter defaults, the purchase commitments of non-defaulting underwriters may also be increased
or the offering may be terminated.</FONT></P>



<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
underwriters propose to offer the shares of common stock directly to the public at the public offering
price set forth on the cover page of this prospectus supplement and to certain dealers at that price less a concession not in excess
of $0.306 per share. After the offering of the shares to the public, the offering price and other selling terms may be changed by
the underwriters. Sales of shares made outside of the United States may be made by affiliates of the underwriters.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0">The underwriters have an option to buy up to 794,117 additional shares of common stock from us to cover sales
of shares by the underwriters which exceed the number of shares specified in the table above. The underwriters have 30&nbsp;days
from the date of this prospectus supplement to exercise this option to purchase additional shares. If any shares are purchased
with this option to purchase additional shares, the underwriters will purchase shares in approximately the same proportion as shown
in the table above. If any additional shares of common stock are purchased, the underwriters will offer the additional shares on
the same terms as those on which the shares are being offered.</P>



<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
underwriting fee is equal to the public offering price per share of common stock less the amount paid
by the underwriters to us per share of common stock. The underwriting fee is $0.51 per share. The following table shows the per
share and total underwriting discounts and commissions to be paid to the underwriters assuming both no exercise and full exercise
of the underwriters&rsquo; option to purchase additional shares.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="border-collapse: collapse; width: 100%">
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="width: 64%; font-size: 10pt; padding-bottom: 1pt; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="width: 1%; font-size: 10pt; font-weight: bold; padding-bottom: 1pt; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 1%; border-bottom: Black 1pt solid; font-size: 10pt; text-align: left; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="width: 15%; border-bottom: Black 1pt solid; font-size: 10pt; text-align: right; border-top: Black 1.5pt solid"><P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0; background-color: Transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Without
                                         exercise of</B><BR> <B>option to purchase additional shares</B></FONT></P></TD><TD STYLE="width: 1%; border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="width: 1%; font-size: 10pt; font-weight: bold; padding-bottom: 1pt; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="width: 1%; border-bottom: Black 1pt solid; font-size: 10pt; text-align: left; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="width: 15%; border-bottom: Black 1pt solid; font-size: 10pt; text-align: right; border-top: Black 1.5pt solid"><P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0; background-color: Transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>With
                                         full</B><BR> <B>exercise of option to purchase additional shares</B></FONT></P></TD><TD STYLE="width: 1%; border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left; border-top: Black 1.5pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Per Share&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">0.51</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;$</FONT></TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">0.51</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: transparent">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Total&#9;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT>$</TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">2,700,000</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT>$</TD><TD STYLE="font-size: 10pt; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">3,105,000</FONT></TD><TD STYLE="font-size: 10pt; text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: right; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD><TD STYLE="font-size: 10pt; text-align: left; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></TD></TR>
</TABLE>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>




<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0">We estimate that the total expenses of this offering, including registration, filing
and listing fees, printing fees and legal and accounting expenses, but excluding the underwriting discounts and commissions, will
be approximately $500,000. We have agreed to reimburse the underwriters for all expenses related to qualification of our common
stock under states securities laws and the clearing of this offering with the Financial Industry Regulatory Authority. In addition,
we have granted to J.P. Morgan Securities LLC the right to participate in any public offering of our common stock until March 21,
2018, subject to certain limitations.</P>



<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">A
prospectus supplement in electronic format may be made available on the web sites maintained by one or more underwriters, or selling
group members, if any, participating in the offering. The underwriters may agree to allocate a number of shares to underwriters
and selling group members for sale to their online brokerage account holders. Internet distributions will be allocated by the
representative to underwriters and selling group members that may make Internet distributions on the same basis as other allocations.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
have agreed, subject to limited exceptions, that we will not (i) offer, pledge, announce the intention to sell, sell, contract
to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant
to purchase or otherwise dispose of, directly or indirectly, or file with the SEC a registration statement under the Securities
Act relating to, any shares of our common stock or securities convertible into or exchangeable or exercisable for any shares of
our common stock, or publicly disclose the intention to make any offer, sale, pledge, disposition or filing, or (ii) enter into
any swap or other arrangement that transfers all or a portion of the economic consequences associated with the ownership of any
shares of common stock or any such other securities (regardless of whether any of these transactions are to be settled by the
delivery of shares of common stock or such other securities, in cash or otherwise), in each case without the prior written consent
of J.P. Morgan Securities LLC for a period of 60 days after the date of this prospectus supplement (the &ldquo;Restricted Period&rdquo;),
other than (A) the shares of our common stock to be sold hereunder (B) shares and options to purchase shares of common stock issued
pursuant to our existing equity compensation plans and (C) any shares of our common stock issued upon the exercise of options
or the vesting of restricted stock units granted under our existing management incentive plans.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
directors and executive officers have entered into lock-up agreements with the underwriters prior to the commencement of this
offering pursuant to which each of these persons, with limited exceptions, for a period of 60 days after the date of this prospectus
supplement, may not, without the prior written consent of J.P. Morgan Securities LLC, (1)&nbsp;offer, pledge, announce the intention
to sell, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option,
right or warrant to purchase, or otherwise transfer or dispose of, directly or indirectly, any shares of our common stock or any
securities convertible into or exercisable or exchangeable for our common stock (including, without limitation, common stock or
such other securities which may be deemed to be beneficially owned by such directors and executive officers in accordance with
the rules and regulations of the SEC and securities which may be issued upon exercise of a stock option or warrant) or (2)&nbsp;enter
into any swap or other agreement that transfers, in whole or in part, any of the economic consequences of ownership of the common
stock or such other securities, whether any such transaction described in clause&nbsp;(1) or (2) above is to be settled by delivery
of common stock or such other securities, in cash or otherwise, or (3) make any demand for or exercise any right with respect
to the registration of any shares of our common stock or any security convertible into or exercisable or exchangeable for our
common stock. Each of the lock-up agreements contain certain exceptions, including the establishment of a contract or plan meeting
the requirements of Rule 10b5-1 under the Exchange Act for the transfer or sale of shares of common stock after the expiration
of a period of 60 days after the date of this prospectus supplement, provided that such plan does not provide for the sale of
common stock during the Restricted Period and, provided further, that no filing by any party under the Exchange Act, or other
public announcement regarding the establishment of such plan, shall be required or shall be voluntarily made during the Restricted
Period; the transfer or sale of shares of common stock pursuant to a 10b5-1 plan that has been entered into by certain of our
executive officers prior to the date hereof and provided any filing required or voluntarily made under the Exchange Act shall
note that such transaction was conducted pursuant to a pre-established 10b5-1 plan; or the disposition of shares of common stock
to the Company for the purpose of covering tax liabilities and/or the exercise price in connection with the exercise of options
to purchase shares of common stock or the vesting of restricted stock units or shares of restricted stock, in each case awarded
pursuant to our existing equity compensation plans, provided that any required filing under the Exchange Act shall clearly indicate
the circumstances of such disposition.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
common stock is listed on the NASDAQ Global Select Market under the symbol &ldquo;BCRX.&rdquo;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
connection with this offering, the underwriters may engage in stabilizing transactions, which involves making bids for, purchasing
and selling shares of common stock in the open market for the purpose of preventing or retarding a decline in the market price
of the common stock while this offering is in progress. These stabilizing transactions may include making short sales of the common
stock, which involves the sale by the underwriters of a greater number of shares of common stock than they are required to purchase
in this offering, and purchasing shares of common stock on the open market to cover positions created by short sales. Short sales
may be &ldquo;covered&rdquo; shorts, which are short positions in an amount not greater than the underwriters&rsquo; option to
purchase additional shares referred to above, or may be &ldquo;naked&rdquo; shorts, which are short positions in excess of that
amount. The underwriters may close out any covered short position either by exercising their option to purchase additional shares,
in whole or in part, or by purchasing shares in the open market. In making this determination, the underwriters will consider,
among other things, the price of shares available for purchase in the open market compared to the price at which the underwriters
may purchase shares through the option to purchase additional shares. A naked short position is more likely to be created if the
underwriters are concerned that there may be downward pressure on the price of the common stock in the open market that could
adversely affect investors who purchase in this offering. To the extent that the underwriters create a naked short position, they
will purchase shares in the open market to cover the position.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
underwriters have advised us that, pursuant to Regulation&nbsp;M of the Securities Act, they may also engage in other activities
that stabilize, maintain or otherwise affect the price of the common stock, including the imposition of penalty bids. This means
that if the representative of the underwriters purchases common stock in the open market in stabilizing transactions or to cover
short sales, the representative can require the underwriters that sold those shares as part of this offering to repay the underwriting
discount received by them.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">These
activities may have the effect of raising or maintaining the market price of the common stock or preventing or retarding a decline
in the market price of the common stock, and, as a result, the price of the common stock may be higher than the price that otherwise
might exist in the open market. If the underwriters commence these activities, they may discontinue them at any time. The underwriters
may carry out these transactions on the NASDAQ Global Select Market, in the over-the-counter market or otherwise.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
addition, in connection with this offering certain of the underwriters (and selling group members) may engage in passive market
making transactions in our common stock on the NASDAQ Stock Market prior to the pricing and completion of this offering. Passive
market making consists of displaying bids on the NASDAQ Stock Market no higher than the bid prices of independent market makers
and making purchases at prices no higher than these independent bids and effected in response to order flow. Net purchases by
a passive market maker on each day are generally limited to a specified percentage of the passive market maker&rsquo;s average
daily trading volume in the common stock during a specified period and must be discontinued when such limit is reached. Passive
market making may cause the price of our common stock to be higher than the price that otherwise would exist in the open market
in the absence of these transactions. If passive market making is commenced, it may be discontinued at any time.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Other
than in the United States, no action has been taken by us or the underwriters that would permit a public offering of the securities
offered by this prospectus supplement in any jurisdiction where action for that purpose is required. The securities offered by
this prospectus supplement may not be offered or sold, directly or indirectly, nor may this prospectus supplement or any other
offering material or advertisements in connection with the offer and sale of any such securities be distributed or published in
any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that
jurisdiction. Persons into whose possession this prospectus supplement comes are advised to inform themselves about and to observe
any restrictions relating to the offering and the distribution of this prospectus supplement. This prospectus supplement does
not constitute an offer to sell or a solicitation of an offer to buy any securities offered by this prospectus supplement in any
jurisdiction in which such an offer or a solicitation is unlawful.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 12pt; margin: 0pt 0; background-color: Transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 12pt"><B>Notice
to Prospective Investors in the European Economic Area</B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>&nbsp;</B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">In
relation to each Member State of the European Economic Area (each, a &ldquo;Relevant Member State&rdquo;), no offer of shares
may be made to the public in that Relevant Member State other than:</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt"><TR STYLE="vertical-align: top"><TD STYLE="width: 20px"></TD><TD STYLE="width: 20px"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">A.</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">to
                                         any legal entity which is a qualified investor as defined in the Prospectus Directive;&nbsp;</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; margin: 0pt 0 0pt 0.5in; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt"><TR STYLE="vertical-align: top"><TD STYLE="width: 20px"></TD><TD STYLE="width: 20px"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">B.</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">to
                                         fewer than 100 or, if the Relevant Member State has implemented the relevant provision
                                         of the 2010 PD Amending Directive, 150, natural or legal persons (other than qualified
                                         investors as defined in the Prospectus Directive), as permitted under the Prospectus
                                         Directive, subject to obtaining the prior consent of the representative; or</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; margin: 0pt 0 0pt 0.5in; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt"><TR STYLE="vertical-align: top"><TD STYLE="width: 20px"></TD><TD STYLE="width: 20px"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">C.</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">in
                                         any other circumstances falling within Article 3(2) of the Prospectus Directive,</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0 0pt 0.5in; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">provided
that no such offer of shares shall require the Company or the representative to publish a prospectus pursuant to Article 3 of
the Prospectus Directive or supplement a prospectus pursuant to Article 16 of the Prospectus Directive.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0 0pt 0.5in; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Each
person in a Relevant Member State who initially acquires any shares or to whom any offer is made will be deemed to have represented,
acknowledged and agreed that it is a &ldquo;qualified investor&rdquo; within the meaning of the law in that Relevant Member State
implementing Article 2(1)(e) of the Prospectus Directive.&nbsp; In the case of any shares being offered to a financial intermediary
as that term is used in Article 3(2) of the Prospectus Directive, each such financial intermediary will be deemed to have represented,
acknowledged and agreed that the shares acquired by it in the offer have not been acquired on a non-discretionary basis on behalf
of, nor have they been acquired with a view to their offer or resale to, persons in circumstances which may give rise to an offer
of any shares&nbsp; to the public other than their offer or resale in a Relevant Member State to qualified investors as so defined
or in circumstances in which the prior consent of the representative has been obtained to each such proposed offer or resale.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
Company, the representative and their affiliates will rely upon the truth and accuracy of the foregoing representations, acknowledgements
and agreements.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">This
prospectus supplement has been prepared on the basis that any offer of shares in any Relevant Member State will be made pursuant
to an exemption under the Prospectus Directive from the requirement to publish a prospectus for offers of shares. Accordingly,
any person making or intending to make an offer in that Relevant Member State of shares which are the subject of the offering
contemplated in this prospectus supplement may only do so in circumstances in which no obligation arises for the Company or any
of the underwriters to publish a prospectus pursuant to Article 3 of the Prospectus Directive in relation to such offer.&nbsp;
Neither the Company nor the underwriters have authorized, nor do they authorize, the making of any offer of shares in circumstances
in which an obligation arises for the Company or the underwriters to publish a prospectus for such offer.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">For
the purpose of the above provisions, the expression &ldquo;an offer to the public&rdquo; in relation to any shares in any Relevant
Member State means the communication in any form and by any means of sufficient information on the terms of the offer and the
shares to be offered so as to enable an investor to decide to purchase or subscribe the shares, as the same may be varied in the
Relevant Member State by any measure implementing the Prospectus Directive in the Relevant Member State and the expression &ldquo;Prospectus
Directive&rdquo; means Directive 2003/71/EC (including the 2010 PD Amending Directive, to the extent implemented in the Relevant
Member States) and includes any relevant implementing measure in the Relevant Member State and the expression &ldquo;2010 PD Amending
Directive&rdquo; means Directive 2010/73/EU.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 12pt; margin: 0pt 0; background-color: Transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 12pt"><B>Notice
to Prospective Investors in the United Kingdom</B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">In
addition, in the United Kingdom, this prospectus supplement is being distributed only to, and is directed only at, and any offer
subsequently made may only be directed at persons who are &ldquo;qualified investors&rdquo; (as defined in the Prospectus Directive)
(i) who have professional experience in matters relating to investments falling within Article 19 (5) of the Financial Services
and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the &ldquo;Order&rdquo;) </FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">and/or
(ii) who are high net worth companies (or persons to whom it may otherwise be lawfully communicated) falling within Article 49(2)(a)
to (d) of the Order (all such persons together being referred to as &ldquo;relevant persons&rdquo;).&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Any
person in the United Kingdom that is not a relevant person should not act or rely on the information included in this prospectus
supplement or use it as basis for taking any action. In the United Kingdom, any investment or investment activity that this prospectus
supplement relates to may be made or taken exclusively by relevant persons. Any person in the United Kingdom that is not a relevant
person should not act or rely on this prospectus supplement or any of its contents.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 12pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Notice
to Prospective Investors in Canada</B></FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
shares of common stock may be sold only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited
investors, as defined in National Instrument 45-106 <I>Prospectus Exemptions</I> or subsection 73.3(1) of the <I>Securities Act
</I>(Ontario), and are permitted clients, as defined in National Instrument 31-103 <I>Registration Requirements, Exemptions and
Ongoing Registrant Obligations</I>. Any resale of the shares of common stock must be made in accordance with an exemption from,
or in a transaction not subject to, the prospectus requirements of applicable securities laws.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Securities
legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this
prospectus supplement (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission
or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser&rsquo;s
province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser&rsquo;s
province or territory for particulars of these rights or consult with a legal advisor.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Pursuant
to section 3A.3 of National Instrument 33-105 <I>Underwriting Conflicts</I> (<B>NI 33-105</B>), the underwriters are not required
to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Certain
of the underwriters and their affiliates have provided in the past to us and our affiliates and may provide from time to time
in the future certain commercial banking, financial advisory, investment banking and other services for us and such affiliates
in the ordinary course of their business, for which they have received and may continue to receive customary fees and commissions.
In addition, from time to time, certain of the underwriters and their affiliates may effect transactions for their own account
or the account of customers, and hold on behalf of themselves or their customers, long or short positions in our debt or equity
securities or loans, and may do so in the future.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 16pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; text-transform: none"><B>Legal
matters</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
validity of the shares of common stock offered by this prospectus supplement will be passed upon for us by Gibson, Dunn &amp;
Crutcher LLP. Certain legal matters in connection with this offering will be passed upon for the underwriters by Latham &amp;
Watkins LLP, San Diego, California.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 16pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; text-transform: none"><B>Experts</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Ernst
&amp; Young LLP, independent registered public accounting firm, has audited our consolidated financial statements included in
our Annual Report on Form 10-K for the year ended December 31, 2016, and the effectiveness of our internal control over financial
reporting as of December 31, 2016, as set forth in their reports, which are incorporated by reference in this prospectus and elsewhere
in the registration statement. Our financial statements and our management&rsquo;s assessment of the effectiveness of internal
control over financial reporting as of December 31, 2016 are incorporated by reference in reliance on Ernst &amp; Young LLP&rsquo;s
reports, given on their authority as experts in accounting and auditing.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 16pt; font-weight: bold; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 16pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; text-transform: none"><B>Where
you can find more information</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
file electronically with the SEC our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K,
proxy statements and other information. We make available on or through our website, http://www.biocryst.com, free of charge,
copies of these filings as soon as reasonably practicable after we electronically file them with or furnish them to the SEC. The
information on our website is not incorporated by reference into this prospectus supplement. You can also request copies of such
documents by contacting our Investor Relations Department at 4505 Emperor Blvd., Suite 200, Durham, North Carolina 27703 or sending
an email to investorrelations@biocryst.com. You may read and copy any document we file at the SEC&rsquo;s Public Reference Room
at 100 F Street NE, Washington, D.C. 20549. You can also obtain copies of this information by mail from the Public Reference Room
of the SEC at prescribed rates. You may obtain information on the operation of the Public Reference Room by calling the SEC at
(800) SEC-0330.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
SEC also maintains a website that contains reports, proxy statements and other information about issuers, like BioCryst, that
file electronically with the SEC. The address of that site is http://www.sec.gov. Unless specifically listed below under &ldquo;Incorporation
of Certain Documents by Reference&rdquo; the information contained on the SEC website is not incorporated by reference into this
prospectus supplement.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
have filed with the SEC a registration statement on Form S-3 that registers the securities we are offering. The registration statement,
including the attached exhibits and schedules, contains additional relevant information about us and our securities. The rules
and regulations of the SEC allow us to omit certain information included in the registration statement from this prospectus supplement.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 16pt; text-transform: uppercase; text-align: left; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; text-transform: none"><B>Incorporation
of certain documents by reference</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
SEC allows us to &ldquo;incorporate by reference&rdquo; information into this prospectus supplement. This means that we can disclose
important information to you by referring you to another document filed separately with the SEC. The information incorporated
by reference is considered to be part of this prospectus supplement, except for any information that is superseded by information
that is included directly in this document.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">This
prospectus supplement includes by reference the documents listed below that we have previously filed with the SEC and that are
not included in or delivered with this document. They contain important information about us and our financial condition.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
                                         Annual Report on Form 10-K for the year ended December 31, 2016, filed with the SEC on
                                         February 27, 2017;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
                                         information in our Definitive Proxy Statement, filed with the SEC on April 11, 2016,
                                         set forth under the captions &ldquo;Items to be Voted on &mdash; 1. Election of Directors,&rdquo;
                                         &ldquo;Executive Officers,&rdquo; &ldquo;Section 16(a) Beneficial Ownership Reporting
                                         Compliance,&rdquo; &ldquo;Corporate Governance,&rdquo; &ldquo;Compensation Discussion
                                         and Analysis,&rdquo; &ldquo;Summary Compensation Table,&rdquo; &ldquo;Grants of Plan-Based
                                         Awards in 2015,&rdquo; &ldquo;Outstanding Equity Awards at December&nbsp;31, 2015,&rdquo;
                                         &ldquo;2015 Option Exercises and Stock Vested,&rdquo; &ldquo;Potential Payments Upon
                                         Termination or Change in Control,&rdquo; &ldquo;2015 Director Compensation,&rdquo; &ldquo;Compensation
                                         Committee Interlocks and Insider Participation,&rdquo; &ldquo;Compensation Committee
                                         Report,&rdquo; &ldquo;Equity Compensation Plan Information,&rdquo; &ldquo;Security Ownership
                                         of Certain Beneficial Owners and Management,&rdquo; &ldquo;Certain Relationships and
                                         Related Transactions,&rdquo; and &ldquo;Items to be Voted on &mdash; 2. Ratification
                                         of Appointment of Independent Registered Public Accountants&rdquo;;</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
                                         Current Report on Form 8-K filed with the SEC on February 27, 2017; and</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 0pt; margin-bottom: 0pt; background-color: transparent"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
                                         description of our common stock contained in our Registration Statement on Form 8-A (File
                                         No. 000-23186) filed with the SEC on January 8, 1994, including any amendment or reports
                                         filed for the purpose of updating such description.</FONT></TD></TR></TABLE>

<P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">All
documents filed by us pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus supplement
and prior to the termination of this offering shall be deemed to be incorporated by reference herein and to be a part of this
prospectus supplement from the date of filing of such documents. We are not, however, incorporating by reference any documents
or portions thereof, whether specifically listed above or filed in the future, that are not deemed &ldquo;filed&rdquo; with the
SEC, including any information furnished under Item 2.02 or Item 7.01 of any Current Report on Form 8-K and exhibits filed on
such form that are related to such items. Any statement contained in a document incorporated by reference herein shall be deemed
to be modified or superseded for purposes of this prospectus supplement to the extent that a statement contained herein or in
any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes
such statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute
a part of this prospectus supplement.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">You
can obtain any of the documents incorporated by reference in this prospectus supplement from us without charge, excluding any
exhibits to those documents unless the exhibit is specifically incorporated by reference as an exhibit to this prospectus supplement
by requesting them in writing or by telephone from us at the following address and telephone number:</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Investor
Relations</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">BioCryst
Pharmaceuticals, Inc.</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">4505
Emperor Blvd., Suite 200</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Durham,
North Carolina 27703</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">(919)
859-7910</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Neither
we nor the underwriters have authorized anyone to provide you with information different from that contained or incorporated by
reference in this prospectus supplement, the accompanying prospectus or any free writing prospectus prepared by us or on our behalf.
We and the underwriters take no responsibility for, or can provide no assurances as to the reliability of, any information other
than the information contained or incorporated by reference in this prospectus supplement, the accompanying prospectus or any
free writing prospectus prepared by us or on our behalf. If you are in a jurisdiction where offers to sell, or solicitations of
offers to purchase, the securities offered by this document are unlawful, or if you are a person to whom it is unlawful to direct
these types of activities, then the offer presented in this document does not extend to you.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0; background-color: transparent"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 14pt; text-align: center; margin: 0pt 0; background-color: transparent"></P>

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<P STYLE="font-size: 10pt; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>PROSPECTUS</B></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><IMG SRC="logo2.jpg" ALT=""></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>$150,000,000</B></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Common Stock</B><BR>
<B>Preferred Stock</B><BR>
<B>Depositary Shares</B><BR>
<B>Stock Purchase Contracts</B><BR>
<B>Warrants</B><BR>
<B>Units</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.25in; margin: 12pt 0 0 9pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">By
this prospectus, we may from time to time offer securities to the public. We will provide specific terms of these securities in
supplements to this prospectus. You should read this prospectus, the applicable prospectus supplement, and the information incorporated
by reference in this prospectus and the applicable prospectus supplement carefully before you invest.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.25in; margin: 12pt 0 0 9pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
common stock, par value $0.01 per share, trades on the NASDAQ Global Select Market under the symbol &ldquo;BCRX.&rdquo;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.25in; margin: 12pt 0 0 9pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
have not authorized anyone else to make additional representations or to provide you with information other than information provided
or incorporated by reference in this prospectus or any prospectus supplement. We take no responsibility for, and can provide no
assurances as to the reliability of, any other information that others may give you or representations that others may make. We
are not making or soliciting an offer of any securities other than the securities described in this prospectus and any prospectus
supplement. We are not making or soliciting an offer of these securities in any state or jurisdiction where the offer is not permitted
or in any circumstances in which such offer or solicitation is unlawful. You should not assume that the information contained
or incorporated by reference in this prospectus or any prospectus supplement is accurate as of any date other than the date on
the front of those documents.</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">______________</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.25in; margin: 12pt 0 0 9pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Investing
in these securities involves a high degree of risk. See &ldquo;Risk Factors&rdquo; on page 2 of this prospectus, in the applicable
prospectus supplement we will deliver with this prospectus and in the documents incorporated herein and therein by reference.</B></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">______________</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 19.2pt; margin: 12pt 0 0 8.4pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
securities may be sold by us to or through underwriters or dealers, directly to purchasers or through agents designated from time
to time, or through a combination of these methods. For additional information on the methods of sale, you should refer to the
section entitled &ldquo;Plan of Distribution&rdquo; in this prospectus. If any underwriters are involved in the sale of any securities
with respect to which this prospectus is being delivered, the names of such underwriters and any applicable discounts or commissions
and over-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net
proceeds we expect to receive from such sale will also be set forth in a prospectus supplement. This prospectus may not be used
to sell any securities unless accompanied by a prospectus supplement.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.25in; margin: 12pt 0 0 9pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Neither
the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or
passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.</B></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0">The date of this prospectus is April 18, 2016.</P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>TABLE
OF CONTENTS</B></FONT></P>

<P STYLE="font-size: 10pt; margin: 12pt 0 0; text-align: right"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><U>Page</U></FONT></P>



<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%">
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: rgb(204,238,255)">
    <TD STYLE="width: 90%; text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">ABOUT
    THIS PROSPECTUS</FONT></TD>
    <TD STYLE="width: 10%; text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">i</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: White">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">PROSPECTUS
    SUMMARY</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">1</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: rgb(204,238,255)">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">RISK
    FACTORS</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">2</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: White">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">INFORMATION
    REGARDING FORWARD-LOOKING STATEMENTS</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">3</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: rgb(204,238,255)">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">USE
    OF PROCEEDS</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">5</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: White">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">DESCRIPTION
    OF COMMON STOCK, PREFERRED STOCK AND DEPOSITARY SHARES</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">6</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: rgb(204,238,255)">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">DESCRIPTION
    OF STOCK PURCHASE CONTRACTS</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">9</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: White">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">DESCRIPTION
    OF WARRANTS</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">10</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: rgb(204,238,255)">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">DESCRIPTION
    OF UNITS</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">12</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: White">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">PLAN
    OF DISTRIBUTION</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">13</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: rgb(204,238,255)">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">LEGAL
    MATTERS</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">16</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: White">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">EXPERTS</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">16</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: rgb(204,238,255)">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">WHERE
    YOU CAN FIND MORE INFORMATION</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">17</FONT></TD></TR>
<TR STYLE="text-align: left; vertical-align: bottom; font: 10pt Times New Roman, Times, Serif; background-color: White">
    <TD STYLE="text-align: left; text-indent: -0.5in; padding-top: 0in; padding-bottom: 0pt; padding-left: 0.5in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">INCORPORATION
    OF CERTAIN DOCUMENTS BY REFERENCE</FONT></TD>
    <TD STYLE="text-align: right; padding-top: 0in; padding-bottom: 0pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">17</FONT></TD></TR>
</TABLE>
<P STYLE="margin: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="margin-top: 0; text-align: center; margin-bottom: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>ABOUT
THIS PROSPECTUS</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">This
prospectus is part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission, or the SEC,
using a &ldquo;shelf&rdquo; registration or continuous offering process. Under this registration statement, we may sell any combination
of the securities described in this prospectus from time to time, either separately or in units, in one or more offerings. Together,
these offerings may total up to $150.0 million.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">This
prospectus provides you with a general description of the securities we may offer. Each time we sell securities, we will provide
a prospectus supplement containing specific information about the terms of that offering. That prospectus supplement may add,
update or change information contained in this prospectus and will also include the following information:</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         type and amount of securities that we propose to sell;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         public offering price of the securities;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         names of any underwriters, agents or dealers through or to which the securities will
                                         be sold;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         compensation of those underwriters, agents or dealers;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">information
                                         about any securities exchanges or automated quotation systems on which the securities
                                         will be listed or traded;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         risk factors applicable to the securities that we propose to sell; and</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         other material information about the offering and sale of the securities.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If there
is any inconsistency between the information in this prospectus and any prospectus supplement, you should rely on the information
in the prospectus supplement. You should read both this prospectus and any prospectus supplement together with the additional
information described under the heading &ldquo;Where You Can Find More Information.&rdquo; The registration statement containing
this prospectus, including the exhibits to the registration statement, provides additional information about us and the securities
offered under this prospectus. The registration statement, including the exhibits, can be read at the SEC&rsquo;s website or at
the SEC&rsquo;s offices referenced under the heading &ldquo;Where You Can Find More Information.&rdquo;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">All references
to &ldquo;Company,&rdquo; &ldquo;we,&rdquo; &ldquo;our,&rdquo; or &ldquo;us&rdquo; refer solely to BioCryst Pharmaceuticals, Inc.
and not to the persons who manage us or sit on our Board of Directors. All trade names used in this prospectus are either our
registered trademarks or trademarks of their respective holders.</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>PROSPECTUS
SUMMARY</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">This
summary highlights information contained elsewhere or incorporated by reference into this prospectus. Because it is a summary,
it does not contain all of the information that you should consider before investing in our securities. You should read this entire
prospectus carefully, including the section entitled &ldquo;Risk Factors&rdquo; and the documents that we incorporate by reference
into this prospectus, before making an investment decision.</FONT></P>

<P STYLE="font-size: 10pt; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Business of BioCryst Pharmaceuticals,
Inc.</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">We
are a biotechnology company that designs, optimizes and develops novel small molecule drugs that block key enzymes involved in
<FONT STYLE="background-color: white">the pathogenesis of diseases. </FONT></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We
focus on the treatment of rare diseases in which significant unmet medical needs exist and that align with our capabilities and
expertise. We integrate the disciplines of biology, crystallography, medicinal chemistry and computer modeling to discover and
develop small molecule pharmaceuticals through the process known as structure-guided drug design. Structure-guided drug design
is a drug discovery approach by which we design synthetic compounds from detailed structural knowledge of the active sites of
enzyme targets associated with particular diseases. We use X-ray crystallography, computer modeling of molecular structures and
advanced chemistry techniques to focus on the three-dimensional molecular structure and active site characteristics of the enzymes
that control cellular biology. Enzymes are proteins that act as catalysts for many vital biological reactions. Our goal generally
is to design a compound that will fit in the active site of an enzyme and thereby prevent its catalytic activity.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We are
a Delaware corporation originally founded in 1986. Our principal executive offices are located at 4505 Emperor Blvd. Suite 200,
Durham, North Carolina 27703, and our telephone number is (919) 859-1302. For more information about us, please visit our website
at http://www.biocryst.com. The information on our web site is not incorporated by reference into this prospectus.</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>RISK
FACTORS</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Investing
in our securities involves risks. Our business is influenced by many factors that are difficult to predict and beyond our control
and that involve uncertainties that may materially affect our business, results of operations, financial condition or cash flows,
or the value of these securities. These risks and uncertainties are described in the risk factors section of the documents that
are incorporated by reference in this prospectus. Any subsequent prospectus supplement may contain a discussion of additional
risks applicable to an investment in us and the particular type of securities we are offering under such prospectus supplement.
You should carefully consider all of the information contained in or incorporated by reference in this prospectus and in the applicable
prospectus supplement before you invest in our securities.</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>INFORMATION
REGARDING FORWARD-LOOKING STATEMENTS</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">This
prospectus and any subsequent prospectus supplement, including the information we incorporate by reference, contain forward-looking
statements within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended (the &ldquo;Exchange Act&rdquo;),
which are subject to the &ldquo;safe harbor&rdquo; created in Section 21E. All statements other than statements of historical
facts contained in this prospectus, any subsequent prospectus supplement and the information we incorporate by reference are forward-looking
statements. These forward-looking statements can generally be identified by the use of words such as &ldquo;may,&rdquo; &ldquo;will,&rdquo;
&ldquo;intends,&rdquo; &ldquo;plans,&rdquo; &ldquo;believes,&rdquo; &ldquo;anticipates,&rdquo; &ldquo;expects,&rdquo; &ldquo;estimates,&rdquo;
&ldquo;predicts,&rdquo; &ldquo;potential,&rdquo; the negative of these words or similar expressions. Statements that describe
our future plans, strategies, intentions, expectations, objectives, goals or prospects are also forward-looking statements. These
forward-looking statements include, but are not limited to, statements about:</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         initiation, timing, progress and results of our preclinical testing, clinical trials,
                                         and to the extent applicable, post-marketing commitments, for our HAE product candidates,
                                         RAPIVAB, BCX4430, and our other research and development efforts;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         further preclinical development, clinical development, commercialization, or post-marketing
                                         studies by either us or partners of our product candidates and products, including our
                                         HAE program, RAPIVAB, BCX4430, and early stage discovery programs;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         potential funding from our contracts <FONT STYLE="background-color: white">with the Biomedical
                                         Advanced Research and Development Authority within the United States Department of Health
                                         and Human Services (&ldquo;BARDA/HHS&rdquo;) and the National Institute of Allergy and
                                         Infectious Diseases within the United States Department of Health and Human Services
                                         (&ldquo;NIAID/HHS&rdquo;) for the development of BCX4430</FONT>;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         potential for government stockpiling orders of RAPIVAB, additional regulatory approvals
                                         of RAPIVAB or milestones royalties or profit from commercial sales of RAPIVAB by us or
                                         our partners;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         potential use of RAPIVAB as a treatment for H1N1, H5N1, and H7N9 or other strains of
                                         influenza;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         implementation of our business model, strategic plans for our business, products, product
                                         candidates and technology;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to establish and maintain collaborations or out-license rights to our drug candidates;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">plans,
                                         programs, progress and potential success of our collaborations, including Sequirus UK
                                         Limited (&ldquo;SUL&rdquo;) for RAPIVAB, Mundipharma International Holdings Limited (&ldquo;Mundipharma&rdquo;)
                                         for forodesine and Shionogi &amp; Co., Ltd. (&ldquo;Shionogi&rdquo;) and Green Cross
                                         Corporation (&ldquo;Green Cross&rdquo;) for peramivir in their territories;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">JPR
                                         Royalty Sub LLC&rsquo;s (&ldquo;Royalty Sub&rdquo;) ability to service its payment obligations
                                         in respect of the PhaRMA Notes, and our ability to benefit from our equity interest in
                                         Royalty Sub;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         foreign currency hedge agreement entered into by us in connection with the issuance by
                                         Royalty Sub of the PhaRMA Notes;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         scope of protection we are able to establish and maintain for intellectual property rights
                                         covering our products, product candidates and technology;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to operate our business without infringing the intellectual property rights of
                                         others;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">estimates
                                         of our expenses, revenues, capital requirements and our needs for additional financing;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         timing or likelihood of regulatory filings or regulatory agreements, deferrals and approvals;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         ability to raise additional capital to fund our operations;</FONT></TD></TR></TABLE>

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<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">our
                                         financial performance; and</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">competitive
                                         companies, technologies and our industry.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">These
statements relate to future events or to our future financial performance and involve known and unknown risks, uncertainties and
other important factors that may cause our actual results, performance or achievements to be materially different from any future
results, performance or achievements expressed or implied by these forward-looking statements. Factors that may cause actual results
to differ materially from current expectations include, among other things, those listed under &ldquo;Risk Factors&rdquo; and
elsewhere in this prospectus, any subsequent prospectus supplement and the documents incorporated by reference. Any forward-looking
statement reflects our current views with respect to future events and is subject to these and other risks, uncertainties and
assumptions relating to our operations, results of operations, industry and future growth. Except as required by law, we assume
no obligation to update or revise these forward-looking statements for any reason, even if new information becomes available in
the future.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Discussions
containing these forward-looking statements are also contained in &ldquo;Management&rsquo;s Discussion and Analysis of Financial
Condition and Results of Operations&rdquo; incorporated by reference from our most recent Annual Report on Form 10-K, our Quarterly
Reports on Form 10-Q for the quarters ended since our most recent Annual Report, our Current Reports on Form 8-K, as well as any
future amendments we make to those filings or future filings with the SEC.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>USE
OF PROCEEDS</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Except
as otherwise described in the applicable prospectus supplement, the net proceeds we expect to receive from the sale of any securities
offered hereunder will be added to our general funds and used for general corporate purposes, which may include, but are not limited
to:</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">funding
                                         development, manufacturing and regulatory activities for avoralstat;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">funding
                                         development, manufacturing and regulatory activities for BCX7353;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">funding
                                         development, manufacturing and regulatory activities for other second generation HAE
                                         compounds;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">post-approval
                                         commitments such as the pediatric study for RAPIVAB&trade;;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">pre-launch
                                         commercial activities for the HAE market;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         advancement of development activities on other rare disease targets;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">funding
                                         our research and development efforts;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">capital
                                         expenditures and enhancing our laboratory facilities; and</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">general
                                         working capital needs.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may
also use a portion of the net proceeds to acquire or invest in businesses, assets, products and technologies that are complementary
to our own, although we are not currently contemplating or negotiating any such acquisitions or investments.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The amount
and timing of these expenditures will depend on a number of factors, including the progress of our research and development efforts
and amounts received under our existing and any future government contracts and collaboration arrangements, as well as the amount
of cash used in our operations. Accordingly, our management will have broad discretion in the application of these proceeds, and
investors will be relying on the judgment of our management with regard to the use of these proceeds. Pending application of the
net proceeds as described above, we intend to invest the net proceeds in investment grade interest bearing instruments.</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>DESCRIPTION
OF COMMON STOCK, PREFERRED STOCK AND DEPOSITARY SHARES</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The following
summary description of our capital stock summarizes general terms and provisions that apply to the capital stock. Because this
is only a summary, it does not contain all of the information that may be important to you. This summary is subject to and qualified
in its entirety by reference to our restated certificate of incorporation, as amended, by-laws, as amended, and the rights agreement,
as amended, each of which are on file with the SEC. See &ldquo;Where You Can Find More Information.&rdquo;</FONT></P>

<P STYLE="font-size: 10pt; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Authorized and Outstanding
Capital Stock</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our authorized
capital stock consists of 200,000,000 shares of common stock, par value $0.01 per share, and 5,000,000 shares of preferred stock,
par value $0.01 per share, of which 200,000 shares are designated Series B Junior Participating Preferred Stock with a par value
of $0.001 per share. On February 24, 2016, there were 73,629,816 shares of common stock outstanding and no shares of preferred
stock outstanding.</FONT></P>

<P STYLE="font-size: 10pt; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Common Stock</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Holders
of our common stock are entitled to one vote per share on all matters submitted to a vote of stockholders and may not cumulate
votes for the election of directors. Common stockholders have the right to receive dividends as and when declared by the Board
of Directors from funds legally available therefor, subject to any preferential dividend rights of any preferred stock then outstanding.
Upon our dissolution or liquidation, common stockholders are entitled to receive all assets legally available for distribution
to stockholders, subject to any preferential rights of any preferred stock then outstanding. Holders of common stock have no preemptive
rights and have no rights to convert their common stock into any other securities.</FONT></P>

<P STYLE="font-size: 10pt; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Preferred Stock</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Preferred
stock may be issued from time to time in one or more series, each such series to have such terms as determined by our Board of
Directors. Our Board of Directors has the authority to determine and fix such voting powers, full or limited, or no voting powers,
and such designations, preferences and relative participating, optional or other special rights, and qualifications, limitations
or restrictions thereof, including without limitation dividend rights, conversion rights, redemption privileges and liquidation
preferences, without further vote or action by our stockholders. We will distribute a prospectus supplement with regard to each
particular series of preferred stock that will describe the terms and provisions of that series of preferred stock. The rights
of the holders of any preferred stock that may be issued may adversely affect the rights of the holders of common stock. The issuance
of preferred stock could make it more difficult for third parties to acquire a majority of our outstanding voting stock.</FONT></P>

<P STYLE="font-size: 10pt; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Anti-Takeover Provisions</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our certificate
of incorporation provides for staggered terms for the members of the board of directors and supermajority approval of the removal
of any member of the board of directors and prevents our stockholders from acting by written consent. Our certificate also requires
supermajority approval of any amendment of these provisions. These provisions and other provisions of our by-laws and of Delaware
law applicable to us could delay or make more difficult a merger, tender offer or proxy contest involving us.</FONT></P>

<P STYLE="font-size: 10pt; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>Depositary Shares</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may,
at our option, elect to offer fractional shares of preferred stock, rather than full shares of preferred stock. If we exercise
this option, we will issue to the public receipts for depositary shares, and each of these depositary shares will represent a
fraction, to be set forth in the applicable prospectus supplement, of a share of a particular series of preferred stock.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The shares
of any series of preferred stock underlying the depositary shares will be deposited under a deposit agreement between us and a
bank or trust company selected by us. The depositary will have its principal office in the United States and a combined capital
and surplus of at least $50,000,000. Subject to the terms of the deposit agreement, each owner of a depositary share will be entitled,
in proportion to the applicable fraction of a share of preferred stock underlying the depositary share, to all the rights and
preferences of the preferred stock underlying that depositary share. Those rights may include dividend, voting, redemption, conversion
and liquidation rights.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"></P>

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<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The depositary
shares will be evidenced by depositary receipts issued under a deposit agreement. Depositary receipts will be distributed to those
persons purchasing the fractional shares of preferred stock underlying the depositary shares, in accordance with the terms of
the offering. The following description of the material terms of the deposit agreement, the depositary shares and the depositary
receipts is only a summary and you should refer to the forms of the deposit agreement and depositary receipts that will be filed
with the SEC in connection with the offering of the specific depositary shares.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Pending
the preparation of definitive engraved depositary receipts, the depositary, upon our written order, may issue temporary depositary
receipts substantially identical to the definitive depositary receipts but not in definitive form. These temporary depositary
receipts would entitle their holders to all the rights of definitive depositary receipts. Temporary depositary receipts would
be exchangeable for definitive depositary receipts at our expense.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><I>Dividends
and Other Distributions</I></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">. The depositary will distribute all
cash dividends or other cash distributions received with respect to the underlying stock to the record holders of depositary shares
in proportion to the number of depositary shares owned by those holders.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If there
were a distribution other than in cash, the depositary would distribute property received by it to the record holders of depositary
shares that are entitled to receive the distribution, unless the depositary determines that it is not feasible to make the distribution.
If this occurs, the depositary, with our approval, would sell the property and distribute the net proceeds from the sale to the
applicable holders.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><I>Withdrawal
of Underlying Preferred Stock</I></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">. Unless we provide otherwise
in a prospectus supplement, holders may surrender depositary receipts at the principal office of the depositary and, upon payment
of any unpaid amount due to the depositary, would be entitled to receive the number of whole shares of underlying preferred stock
and all money and other property represented by the related depositary shares. We will not issue any partial shares of preferred
stock. If the holder delivers depositary receipts evidencing a number of depositary shares that represent more than a whole number
of shares of preferred stock, the depositary will issue a new depositary receipt evidencing the excess number of depositary shares
to that holder.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><I>Redemption
of Depositary Shares</I></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">. If a series of preferred stock represented
by depositary shares were subject to redemption, the depositary shares would be redeemed from the proceeds received by the depositary
resulting from the redemption, in whole or in part, of that series of underlying stock held by the depositary. The redemption
price per depositary share would be equal to the applicable fraction of the redemption price per share payable with respect to
that series of underlying stock. Whenever we redeem shares of underlying stock that are held by the depositary, the depositary
will redeem, as of the same redemption date, the number of depositary shares representing the shares of underlying stock so redeemed.
If fewer than all the depositary shares are to be redeemed, the depositary shares to be redeemed will be selected by lot or proportionately,
as may be determined by the depositary.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><I>Voting</I></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">.
Upon receipt of notice of any meeting at which the holders of the underlying stock are entitled to vote, the depositary will mail
the information contained in the notice to the record holders of the depositary shares underlying the preferred stock. Each record
holder of the depositary shares on the record date, which will be the same date as the record date for the underlying stock, will
be entitled to instruct the depositary as to the exercise of the voting rights pertaining to the amount of the underlying stock
represented by that holder's depositary shares. The depositary will then try, as far as practicable, to vote the number of shares
of preferred stock underlying those depositary shares in accordance with those instructions, and we will agree to take all actions
which may be deemed necessary by the depositary to enable the depositary to do so. The depositary will not vote the underlying
shares to the extent it does not receive specific instructions from the holders of depositary shares underlying the preferred
stock.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><I>Conversion
of Preferred Stock</I></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">. If the prospectus supplement relating to
the depositary shares provides that the deposited preferred stock is convertible into or exchangeable for common stock or preferred
stock of another series of BioCryst or securities of any third party, the following will apply. The depositary shares, as such,
will not be convertible into or exchangeable for any securities of BioCryst or any third party. Rather, any holder of the depositary
shares may surrender the related depositary receipts to the depositary with written instructions to instruct us to cause conversion
or exchange of the preferred stock represented by the depositary shares into or for whole shares of common stock or shares of
another series of preferred stock of BioCryst or securities of the relevant third party, as applicable. Upon receipt of those
instructions and any amounts payable by the holder in connection with the conversion or exchange, we will cause the conversion
or exchange using the same procedures as those provided for conversion or exchange of the deposited preferred stock. If only some
of the depositary shares are to be converted or exchanged, a new depositary receipt or receipts will be issued for any depositary
shares not to be converted or exchanged.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"></P>

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<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><I>Amendment
and Termination of the Depositary Agreement</I></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">. The form of depositary
receipt evidencing the depositary shares and any provision of the deposit agreement may be amended at any time by agreement between
us and the depositary. However, any amendment which materially and adversely alters the rights of the holders of depositary shares
will not be effective unless the amendment has been approved by the holders of at least a majority of the depositary shares then
outstanding. The deposit agreement may be terminated by us or by the depositary only if (a) all outstanding depositary shares
have been redeemed or converted or exchanged for any other securities into which the underlying preferred stock is convertible
or exchangeable or (b) there has been a final distribution of the underlying stock in connection with our liquidation, dissolution
or winding up and the underlying stock has been distributed to the holders of depositary receipts.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><I>Charges
of Depositary</I></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">. We will pay all transfer and other taxes and
governmental charges arising solely from the existence of the depositary arrangements. We will also pay charges of the depositary
in connection with the initial deposit of the underlying stock and any redemption of the underlying stock. Holders of depositary
receipts will pay other transfer and other taxes and governmental charges and those other charges, including a fee for any permitted
withdrawal of shares of underlying stock upon surrender of depositary receipts, as are expressly provided in the deposit agreement
to be for their accounts.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><I>Reports</I></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">.
The depositary will forward to holders of depositary receipts all reports and communications from us that we deliver to the depositary
and that we are required to furnish to the holders of the underlying stock.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><I>Limitation
on Liability</I></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">. Neither we nor the depositary will be liable
if either of us is prevented or delayed by law or any circumstance beyond our control in performing our respective obligations
under the deposit agreement. Our obligations and those of the depositary will be limited to performance in good faith of our respective
duties under the deposit agreement. Neither we nor the depositary will be obligated to prosecute or defend any legal proceeding
in respect of any depositary shares or underlying stock unless satisfactory indemnity is furnished. We and the depositary may
rely upon written advice of counsel or accountants, or upon information provided by persons presenting underlying stock for deposit,
holders of depositary receipts or other persons believed to be competent and on documents believed to be genuine.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt"><I>Resignation
and Removal of Depositary</I></FONT><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">. The depositary may resign at any
time by delivering notice to us of its election to resign. We may remove the depositary at any time. Any resignation or removal
will take effect upon the appointment of a successor depositary and its acceptance of the appointment. The successor depositary
must be appointed within 60 days after delivery of the notice of resignation or removal and must be a bank or trust company having
its principal office in the United States and having a combined capital and surplus of at least $50,000,000.</FONT></P>

<P STYLE="font-size: 10pt; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>&nbsp;</B></FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>DESCRIPTION
OF STOCK PURCHASE CONTRACTS</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The following
is a general description of the terms of the stock purchase contracts we may issue from time to time. Particular terms of any
stock purchase contracts we offer will be described in the prospectus supplement relating to such stock purchase contracts. Material
U.S. federal income tax considerations applicable to the stock purchase contracts will also be discussed in the applicable prospectus
supplement. You should refer to the form of stock purchase contract and stock purchase certificate that we will file with the
SEC in connection with the offering of the specific stock purchase contracts for more complete information.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may
issue stock purchase contracts, including contracts obligating holders to purchase from us, and obligating us to sell to holders,
a specified number of shares of common stock, preferred stock or depositary shares at a future date. The consideration per share
of common stock, preferred stock or depositary shares may be fixed at the time that the stock purchase contracts are issued or
may be determined by reference to a specific formula set forth in the stock purchase contracts. Any stock purchase contract may
include anti-dilution provisions to adjust the number of shares issuable pursuant to such stock purchase contract upon the occurrence
of certain events.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The applicable
prospectus supplement will describe the terms of any stock purchase contracts in respect of which this prospectus is being delivered,
including, to the extent applicable, the following:</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">whether
                                         the stock purchase contracts obligate the holder or us to purchase or sell, or both purchase
                                         and sell, the securities subject to purchase under the stock purchase contract, and the
                                         nature and amount of each of those securities, or the method of determining those amounts;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">whether
                                         the stock purchase contracts are to be prepaid or not;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">whether
                                         the stock purchase contracts will be issued as part of a unit and, if so, the other securities
                                         comprising the unit;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">whether
                                         the stock purchase contracts are to be settled by delivery, or by reference or linkage
                                         to the value, performance, or level of the securities subject to purchase under the stock
                                         purchase contract;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         acceleration, cancellation, termination, or other provisions relating to the settlement
                                         of the stock purchase contracts; and</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">whether
                                         the stock purchase contracts will be issued in full registered or global form.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"></P>


<P STYLE="font-size: 10pt; margin: 0pt 0">&nbsp;</P>



<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"></FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>DESCRIPTION
OF WARRANTS</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may
issue warrants to purchase our preferred stock, depositary shares or common stock or any combination thereof. Warrants may be
issued independently or together with any other securities in the form of units, and may be attached to, or separate from, such
securities. The terms of any warrants to be issued and a description of the material provisions of the applicable warrant agreement
will be set forth in the applicable prospectus supplement. Each series of warrants will be issued under a separate warrant agreement
to be entered into between us and a bank or trust company, as warrant agent. You should refer to the form of warrant agreement
and warrant that we file with the SEC in connection with the offering of the specific warrants for more complete information.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The prospectus
supplement will describe the terms of any warrants being offered, including:</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         title and the aggregate number of warrants;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         price or prices at which the warrants will be issued;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         currency or currencies in which the price of the warrants will be payable;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         securities or other rights, including rights to receive payment in cash or securities
                                         based on the value, rate or price of one or more specified commodities, currencies, securities
                                         or indices, or any combination of the foregoing, purchasable upon exercise of the warrants;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         price at which, and the currency or currencies in which, the securities or other rights
                                         purchasable upon exercise of such warrants may be purchased;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         periods during which, and places at which, the warrants are exercisable;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         date or dates on which the warrants shall commence and the date or dates on which the
                                         warrants will expire;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         terms of any mandatory or optional call provisions;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         price or prices, if any, at which the warrants may be redeemed at the option of the holder
                                         or will be redeemed upon expiration;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">whether
                                         the warrants will be sold separately or with other securities as part of a unit;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">if
                                         applicable, the designation and terms of the securities with which the warrants are issued
                                         and the number of warrants issued with each such security;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">if
                                         applicable, the date on and after which the warrants and the related securities will
                                         be separately transferable;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         provisions for the adjustment of the number or amount of securities receivable upon exercise
                                         of warrants;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         identity of the warrant agent;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         exchanges, if any, on which the warrants may be listed;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         maximum or minimum number of warrants which may be exercised at any time;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">if
                                         applicable, a discussion of any material United States federal income tax considerations;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">whether
                                         the warrants shall be issued in book-entry form; and</FONT></TD></TR></TABLE>

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<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         other terms of the warrants, including terms, procedures and limitations relating to
                                         the exchange and exercise of the warrants.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>DESCRIPTION
OF UNITS</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may
issue units consisting of one or more of the other securities described in this prospectus in any combination, as described in
a prospectus supplement. We may issue units in one or more series, which will be described in a prospectus supplement. We will
issue the units or hybrid securities under one or more unit agreements, each referred to as a unit agreement, to be entered into
between us and a bank or trust company, as unit agent. You should refer to the form of unit agreement and unit certificate that
we file with the SEC in connection with the offering of the specific units for more complete information.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The applicable
prospectus supplement will describe:</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         designation and the terms of the units and of the securities constituting the units,
                                         including whether and under what circumstances the securities comprising the units may
                                         be traded separately;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         additional terms of the governing unit agreement;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         additional provisions for the issuance, payment, settlement, transfer or exchange of
                                         the units or of the preferred stock, common stock, stock purchase contracts, depositary
                                         shares or warrants constituting the units; and</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         applicable United States federal income tax consequences.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: -19.2pt; margin: 6pt 0 0 19.2pt"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>PLAN
OF DISTRIBUTION</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may
sell the securities being offered hereby at prices and under terms then prevailing, at prices related to the then current market
price or in negotiated transactions from time to time in one or more of the following ways:</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">directly
                                         to one or more purchasers;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">through
                                         one or more underwriters on a firm commitment or best-efforts basis;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD STYLE="text-align: left"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">through
                                         broker-dealers, who may act as agents or principals, including a block trade in which
                                         a broker or dealer so engaged will attempt to sell as agent but may position and resell
                                         a portion of the block as principal to facilitate the transaction;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">through
                                         agents;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">through
                                         remarketing firms;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">in
                                         privately negotiated transactions; or</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">in
                                         any combination of these methods of sale.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We will
set forth in a prospectus supplement the terms of the offering of securities, including:</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         name or names of any underwriters, dealers or agents;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">the
                                         number of securities and purchase price of the securities being offered and the proceeds
                                         we will receive from the sale;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         underwriting discounts and commissions or agency fees and other items constituting underwriters&rsquo;
                                         or agents&rsquo; compensation;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         over-allotment options under which underwriters may purchase additional securities from
                                         us;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         delayed delivery arrangements;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         discounts or concessions allowed or re-allowed or paid to dealers; and</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">any
                                         securities exchange on which the securities may be listed.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The distribution
of the securities may be effected from time to time in one or more transactions at a fixed price or prices, which may be changed,
at market prices prevailing at the time of sale, at prices related to the prevailing market prices or at negotiated prices.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may
designate agents who agree to use their reasonable efforts to solicit purchases for the period of their appointment or to sell
securities on a continuing basis. Agents may receive compensation in the form of commissions, discounts or concessions from us.
Agents may also receive compensation from the purchasers of the securities for whom they sell as principals. Each particular agent
will receive compensation in amounts negotiated in connection with the sale, which might be in excess of customary commissions.
Agents and any other participating broker-dealers may be deemed to be &ldquo;underwriters&rdquo; within the meaning of Section
2(11) of the Securities Act of 1933 (the &ldquo;Securities Act&rdquo;) in connection with sales of the securities. Accordingly,
any commission, discount or concession received by them and any profit on the resale of the securities purchased by them may be
deemed to be underwriting discounts or commissions under the Securities Act. We have not entered into any agreements, understandings
or arrangements with any underwriters or broker-dealers regarding the sale of their securities. As of the date of this prospectus,
there are no special selling arrangements between any broker-dealer or other person and us. No period of time has been fixed within
which the securities will be offered or sold.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"></P>

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<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If required
under applicable state securities laws, we will sell the securities only through registered or licensed brokers or dealers. In
addition, in some states, we may not sell securities unless they have been registered or qualified for sale in the applicable
state or an exemption from the registration or qualification requirement is available and complied with.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If we
use underwriters for a sale of securities, the underwriters will acquire the securities for their own account. The underwriters
may resell the securities in one or more transactions, including negotiated transactions, at a fixed public offering price or
at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject
to the conditions set forth in the applicable underwriting agreement. We may change from time to time any initial public offering
price and any discounts or concessions the underwriters allow or re-allow or pay to dealers. We may use underwriters with whom
we have a material relationship. We will describe in the prospectus supplement naming the underwriter the nature of any such relationship.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may
use a remarketing firm to offer to sell the securities in connection with a remarketing arrangement upon their purchase. Remarketing
firms will act as principals for their own account or as agents for us. These remarketing firms will offer or sell the securities
pursuant to the terms of the securities. A prospectus supplement will identify any remarketing firm and the terms of its agreement,
if any, with us and will describe the remarketing firm&rsquo;s compensation. Remarketing firms may be deemed to be underwriters
in connection with the securities they remarket.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">If we
offer and sell securities through a dealer, we or an underwriter will sell the securities to the dealer, as principal. The dealer
may then resell the securities to the public at varying prices to be determined by the dealer at the time of resale. Any such
dealer may be deemed to be an underwriter of the securities so offered and sold. The name of the dealer and the terms of the transactions
will be set forth in the applicable prospectus supplement.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may
also sell securities directly to one or more purchasers without using underwriters or agents. Underwriters, dealers and agents
that participate in the distribution of the securities may be underwriters as defined in the Securities Act and any discounts
or commissions they receive from us and any profit on their resale of the securities may be treated as underwriting discounts
and commissions under the Securities Act.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We will
identify in the applicable prospectus supplement any underwriters, dealers or agents and will describe their compensation. We
may have agreements with the underwriters, dealers and agents to indemnify them against specified civil liabilities, including
liabilities under the Securities Act. Underwriters, dealers and agents may engage in transactions with or perform services for
us in the ordinary course of their businesses.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may
authorize agents, dealers or underwriters to solicit offers to purchase securities at the public offering price under delayed
delivery contracts. The terms of these delayed delivery contracts, including when payment for and delivery of the securities sold
will be made under the contracts and any conditions to each party&rsquo;s performance set forth in the contracts, will be described
in the applicable prospectus supplement. The compensation received by underwriters, agents or dealers soliciting purchases of
securities under delayed delivery contracts will be described in the applicable prospectus supplement.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We may
enter into derivative or other hedging transactions with third parties, or sell securities not covered by this prospectus to third
parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with those derivatives,
the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short
sale transactions. If so, the third party may use securities pledged by us or borrowed from us or others to settle those sales
or to close out any related open borrowings of stock, and may use securities received from us in settlement of those derivatives
to close out any related open borrowings of stock. We may also loan or pledge securities covered by this prospectus and the applicable
prospectus supplement to third parties, who may sell the loaned securities or, in an event of default in the case of a pledge,
sell the pledged securities pursuant to this prospectus and the applicable prospectus supplement.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Unless
otherwise specified in the related prospectus supplement, all securities we offer, other than common stock, will be new issues
of securities with no established trading market. Any underwriters may make a market in these securities, but will not be obligated
to do so and may discontinue any market making at any time without notice. We may apply to list any series of securities on an
exchange, but we are not obligated to do so. Therefore, no assurance can be given as to the liquidity of, or the trading market
for, any series of securities.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"></P>

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<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Any underwriter
may engage in overallotment, stabilizing transactions, short covering transactions and penalty bids in accordance with Regulation
M under the Exchange Act. Overallotment involves sales in excess of the offering size, which create a short position. Stabilizing
transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum.
Short covering transactions involve purchases of the securities in the open market after the distribution is completed to cover
short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally
sold by the dealer are purchased in a covering transaction to cover short positions. Those activities may cause the price of the
securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any
time. These transactions may be effected on The NASDAQ Global Select Market or otherwise.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Any underwriters
who are qualified market makers on The NASDAQ Global Select Market may engage in passive market making transactions in the common
stock on The NASDAQ Global Select Market in accordance with Rule 103 of Regulation M, during the business day before the pricing
of the offering, before the commencement of offers or sales of the common stock. Passive market makers must comply with applicable
volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display
its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the
passive market maker&rsquo;s bid, however, the passive market maker&rsquo;s bid must then be lowered when certain purchase limits
are exceeded.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We will
bear all costs, expenses and fees in connection with the registration of the securities, as well as the expense of all commissions
and discounts, if any, attributable to sales of the securities by us.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>LEGAL
MATTERS</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Gibson,
Dunn &amp; Crutcher LLP has rendered an opinion with respect to the validity of the securities being offered by this prospectus.
We have filed this opinion as an exhibit to the registration statement of which this prospectus is a part. If counsel for any
underwriters passes on legal matters in connection with an offering made by this prospectus, we will name that counsel in the
prospectus supplement relating to that offering.</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>EXPERTS</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Ernst
&amp; Young LLP, independent registered public accounting firm, has audited our consolidated financial statements included in
our Annual Report on Form 10-K for the year ended December 31, 2015, and the effectiveness of our internal control over financial
reporting as of December 31, 2015, as set forth in their reports, which are incorporated by reference in this prospectus and elsewhere
in the registration statement. Our financial statements are incorporated by reference in reliance on Ernst &amp; Young LLP's reports,
given on their authority as experts in accounting and auditing.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; font-weight: bold; text-align: center; margin: 12pt 0.5in 0"></P>

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    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt">&nbsp;</DIV>
    <!-- Field: /Page -->

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>WHERE
YOU CAN FIND MORE INFORMATION</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We file
electronically with the SEC our annual reports on Form 10-K, quarterly interim reports on Form 10-Q, current reports on Form 8-K,
proxy statements and other information. We make available on or through our website, http://www.biocryst.com, free of charge,
copies of these filings as soon as reasonably practicable after we electronically file them with or furnish them to the SEC. The
information on our website is not incorporated by reference into this prospectus. You can also request copies of such documents
by contacting our Investor Relations Department at 4505 Emperor Blvd., Suite 200, Durham, North Carolina 27703 or sending an email
to investorrelations@biocryst.com. You may read and copy any document we file at the SEC&rsquo;s Public Reference Room at 100
F Street NE, Washington, D.C. 20549. You can also obtain copies of this information by mail from the Public Reference Room of
the SEC at prescribed rates. You may obtain information on the operation of the Public Reference Room by calling the SEC at (800)
SEC-0330.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The SEC
also maintains an Internet site that contains reports, proxy and information statements, and other information about issuers,
like BioCryst, that file electronically with the SEC. The address of that site is http://www.sec.gov. Unless specifically listed
below under &ldquo;Incorporation of Certain Documents by Reference&rdquo; the information contained on the SEC website is not
incorporated by reference into this prospectus.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We have
filed with the SEC a registration statement on Form S-3 that registers the securities we are offering. The registration statement,
including the attached exhibits and schedules, contains additional relevant information about us and our securities. The rules
and regulations of the SEC allow us to omit certain information included in the registration statement from this prospectus.</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0.5in 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif"><B>INCORPORATION
OF CERTAIN DOCUMENTS BY REFERENCE</B></FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The SEC
allows us to &ldquo;incorporate by reference&rdquo; information into this prospectus. This means that we can disclose important
information to you by referring you to another document filed separately with the SEC. The information incorporated by reference
is considered to be part of this prospectus, except for any information that is superseded by information that is included directly
in this document.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">This
prospectus includes by reference the documents listed below that we have previously filed with the SEC and that are not included
in or delivered with this document. They contain important information about us and our financial condition.</FONT></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
                                         Annual Report on Form 10-K for the year ended December 31, 2015, filed with the SEC on
                                         February 26, 2016;</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Our
                                         Current Reports on Form 8-K filed with the SEC on January 8, 2016 and February 8, 2016;
                                         and</FONT></TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font-size: 10pt; margin-top: 12pt; margin-bottom: 0"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.25in"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif; font-size: 10pt">&bull;</FONT></TD><TD><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">The
                                         description of our common stock which is contained in our Registration Statement on Form
                                         8-A (File No. 000-23186) filed with the SEC on January 7, 1994, together with the amendment
                                         thereto filed with the SEC on March 14, 1994, including any other amendment or reports
                                         filed for the purpose of updating such description.</FONT></TD></TR></TABLE>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">All documents
filed by us pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act on or after the date of this Amendment No. 1 and
prior to its effectiveness and on or after the date of this prospectus and prior to the termination of our offering of securities
shall be deemed to be incorporated by reference herein and to be a part of this prospectus from the date of filing of such documents,
excluding any information furnished under Item 2.02 or Item 7.01 of any Current Report on Form 8-K and exhibits filed on such
form that are related to such items. Any statement contained in a document incorporated by reference herein shall be deemed to
be modified or superseded for purposes of this prospectus to the extent that a statement contained herein or in any other subsequently
filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any statement
so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this prospectus.</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">You can
obtain any of the documents incorporated by reference in this prospectus from us without charge, excluding any exhibits to those
documents unless the exhibit is specifically incorporated by reference as an exhibit to this prospectus. You can obtain documents
incorporated by reference in this prospectus at no cost by requesting them in writing or by telephone from us at the following
address:</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"></P>

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    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt">&nbsp;</DIV>
    <!-- Field: /Page -->

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">Investor
Relations<BR>
BioCryst Pharmaceuticals, Inc.<BR>
4505 Emperor Blvd., Suite 200<BR>
Durham, North Carolina 27703<BR>
(919) 859-1302</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">We have
not authorized anyone else to make additional representations or to provide you with information other than information provided
or incorporated by reference in this prospectus or any prospectus supplement. We take no responsibility for, and can provide no
assurances as to the reliability of, any other information that others may give you or representations that others may make. If
you are in a jurisdiction where offers to sell, or solicitations of offers to purchase, the securities offered by this document
are unlawful, or if you are a person to whom it is unlawful to direct these types of activities, then the offer presented in this
document does not extend to you.</FONT></P>

<P STYLE="font-size: 10pt; margin: 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 12pt 0 0"><FONT STYLE="font-family: Arial, Helvetica, Sans-Serif">&nbsp;</FONT></P>

<!-- Field: Page; Sequence: 66; Value: 1 -->
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    <!-- Field: /Page -->

<P STYLE="font-size: 18pt; text-align: center; margin: 0pt 0"><B><I>&nbsp;</I></B></P>

<P STYLE="font-size: 18pt; text-align: center; margin: 0pt 0"><B><I>&nbsp;</I></B></P>

<P STYLE="font-size: 18pt; text-align: center; margin: 0pt 0"><B><I>5,294,118 shares</I></B></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><IMG SRC="logo.jpg" ALT=""></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font-size: 10pt; text-indent: 0.5in; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; text-align: center; text-indent: 0.5in; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font-size: 18pt; text-align: center; margin: 0pt 0"><B><I>Common stock </I></B></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 24pt; text-align: center; margin: 0pt 0"><B>Prospectus supplement</B></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 18pt; text-align: center; margin: 0pt 0"><B>J.P. Morgan</B></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><FONT STYLE="font-size: 18pt"><B>Piper Jaffray&nbsp;</B></FONT></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><FONT STYLE="font-size: 18pt"><B>JMP Securities&nbsp;</B></FONT></P>



<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><B></B></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font-size: 10pt; margin: 0pt 0">March 9,
2017</P>

<P STYLE="font-size: 10pt; margin: 0pt 0">&nbsp;</P>

<P STYLE="font-size: 10pt; margin: 0pt 0">&nbsp;</P>



<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"></P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0">&nbsp;</P>

<P STYLE="font-size: 10pt; text-align: center; margin: 12pt 0 0"></P>





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