<SEC-DOCUMENT>0001144204-14-009447.txt : 20140214
<SEC-HEADER>0001144204-14-009447.hdr.sgml : 20140214
<ACCEPTANCE-DATETIME>20140214140332
ACCESSION NUMBER:		0001144204-14-009447
CONFORMED SUBMISSION TYPE:	SC 13G/A
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20140214
DATE AS OF CHANGE:		20140214
GROUP MEMBERS:		PETER KOLCHINSKY
GROUP MEMBERS:		RA CAPITAL HEALTHCARE FUND, L.P.

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ARROWHEAD RESEARCH CORP
		CENTRAL INDEX KEY:			0000879407
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMMERCIAL PHYSICAL & BIOLOGICAL RESEARCH [8731]
		IRS NUMBER:				460408024
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	FILING VALUES:
		FORM TYPE:		SC 13G/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-48710
		FILM NUMBER:		14614456

	BUSINESS ADDRESS:	
		STREET 1:		225 SOUTH LAKE AVENUE
		STREET 2:		SUITE 1050
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91101
		BUSINESS PHONE:		626-304-3400

	MAIL ADDRESS:	
		STREET 1:		225 SOUTH LAKE AVENUE
		STREET 2:		SUITE 1050
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91101

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	INTERACTIVE GROUP INC
		DATE OF NAME CHANGE:	20020509

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	INTERACTIVE INC
		DATE OF NAME CHANGE:	19940224

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			RA CAPITAL MANAGEMENT, LLC
		CENTRAL INDEX KEY:			0001346824
		IRS NUMBER:				830406777
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G/A

	BUSINESS ADDRESS:	
		STREET 1:		20 PARK PLAZA, SUITE 1200
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		617-778-2500

	MAIL ADDRESS:	
		STREET 1:		20 PARK PLAZA, SUITE 1200
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13G/A
<SEQUENCE>1
<FILENAME>v368704_sc13ga.htm
<DESCRIPTION>SC 13G/A
<TEXT>
<HTML>
<HEAD>
     <TITLE></TITLE>
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<BODY STYLE="font: 10pt Times New Roman, Times, Serif">

<P STYLE="margin: 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">UNITED STATES<BR>
SECURITIES AND EXCHANGE COMMISSION<BR>
Washington, D.C. 20549</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SCHEDULE 13G</B>&nbsp;</P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Under the Securities Exchange Act of
1934</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; text-indent: 0in"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; text-indent: 0in"><B>(Amendment No. 2)*</B></P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 100%; border-bottom: Black 1pt solid; font-size: 10pt; text-align: center; font-weight: bold">Arrowhead Research Corporation</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt; text-align: center">(Name of Issuer)</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 100%; border-bottom: Black 1pt solid; font-size: 10pt; text-align: center"><B>Common Stock, $0.001 par value</B></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt; text-align: center">(Title of Class of Securities)</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 100%; border-bottom: Black 1pt solid; font-size: 10pt; text-align: center"><B>042797209</B></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt; text-align: center">(CUSIP Number)</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 100%; border-bottom: Black 1pt solid; font-size: 10pt; text-align: center"><B>December 31, 2013</B></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt; text-align: center">(Date of Event Which Requires Filing of this Statement)</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Check the appropriate box to designate the rule pursuant to
which this Schedule is filed:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 22.3pt"></TD><TD STYLE="width: 18pt"><FONT STYLE="font: 10pt Wingdings">&uml;</FONT></TD><TD>Rule 13d-1(b)</TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 22.3pt"></TD><TD STYLE="width: 18pt"><FONT STYLE="font: 10pt Wingdings">x</FONT></TD><TD>Rule 13d-1(c)</TD></TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 22.3pt"></TD><TD STYLE="width: 18pt"><FONT STYLE="font: 10pt Wingdings">&uml;</FONT></TD><TD>Rule 13d-1(d)</TD></TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">*The remainder of this cover page shall be filled out for a
reporting person&rsquo;s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment
containing information which would alter the disclosures provided in a prior cover page.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">The information required in the remainder of this cover page
shall not be deemed to be &ldquo;filed&rdquo; for the purpose of Section 18 of the Securities Exchange Act of 1934 (&ldquo;<B><I>Act</I></B>&rdquo;)
or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however,
see the Notes).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<TR>
    <TD STYLE="width: 46%; font-size: 10pt"><FONT STYLE="font-size: 10pt">CUSIP No. <B>042797209</B></FONT></TD>
    <TD STYLE="width: 22%; font-size: 12pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 32%; font-size: 10pt"><P STYLE="margin: 0pt 0; text-align: right">Page&nbsp;<U>&nbsp;&nbsp;&nbsp;<B>2</B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</U>&nbsp;of&nbsp;<U>&nbsp;&nbsp;&nbsp;<B>7</B>&nbsp;&nbsp;&nbsp;</U>&nbsp;Pages</P>


</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="margin: 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">1.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Names of Reporting Persons.</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">I.R.S. Identification Nos. of above persons (entities only).</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 9pt"><B>RA Capital Management, LLC</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding: 7.5pt 7.5pt 6pt">&nbsp;</TD>
    <TD STYLE="padding: 7.5pt 7.5pt 6pt"><FONT STYLE="font-size: 10pt">2. </FONT></TD>
    <TD COLSPAN="2" STYLE="padding: 7.5pt 7.5pt 6pt"><FONT STYLE="font-size: 10pt">Check the Appropriate Box if a Member of a Group (See Instructions)</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 3%; padding-bottom: 7pt">&nbsp;</TD>
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 7%; padding-bottom: 7pt">&nbsp;</TD>
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 4%; padding-bottom: 7pt"><FONT STYLE="font-size: 10pt">(a)</FONT></TD>
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 86%; padding-bottom: 7pt"><FONT STYLE="font: 10pt Wingdings">&uml;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt"><FONT STYLE="font-size: 10pt">(b)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt"><FONT STYLE="font: 10pt Wingdings">&uml;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">3.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">SEC Use Only </FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">4.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Citizenship&nbsp;or&nbsp;Place&nbsp;of&nbsp;Organization&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Massachusetts</B></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="4" STYLE="border-bottom: black 1pt solid; padding: 0; width: 15%; text-align: left; vertical-align: middle"><FONT STYLE="font-size: 10pt">Number of</FONT><BR>
<FONT STYLE="font-size: 10pt">Shares</FONT><BR>
<FONT STYLE="font-size: 10pt">Beneficially</FONT><BR>
<FONT STYLE="font-size: 10pt">Owned by</FONT><BR>
<FONT STYLE="font-size: 10pt">Each Reporting</FONT><BR>
<FONT STYLE="font-size: 10pt">Person With</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt; width: 7%"><FONT STYLE="font-size: 10pt">5.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt; width: 78%"><FONT STYLE="font-size: 10pt">Sole&nbsp;Voting&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>0&nbsp;shares</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">6.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Shared&nbsp;Voting&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>3,929,016&nbsp;shares</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">7.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Sole&nbsp;Dispositive&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>0&nbsp;shares</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">8.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Shared&nbsp;Dispositive&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>3,929,016&nbsp;shares</B></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">9.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Aggregate Amount Beneficially Owned by Each Reporting Person</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>3,929,016 shares</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">10.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Check if the Aggregate Amount in Row (9) Excludes&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT STYLE="font-family: Wingdings">&uml;</FONT></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Certain Shares (See Instructions)</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">11.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Percent of Class Represented by Amount in Row (9)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>9.9%</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">12.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Type of Reporting Person (See Instructions)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>IA</B></P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>



<P STYLE="margin: 0"></P>

<P STYLE="margin: 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<TR>
    <TD STYLE="width: 46%; font-size: 10pt"><FONT STYLE="font-size: 10pt">CUSIP No. <B>042797209</B></FONT></TD>
    <TD STYLE="width: 22%; font-size: 12pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 32%; font-size: 10pt"><P STYLE="margin: 0pt 0; text-align: right">Page&nbsp;<U>&nbsp;&nbsp;&nbsp;<B>3</B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</U>&nbsp;of&nbsp;<U>&nbsp;&nbsp;&nbsp;<B>7</B>&nbsp;&nbsp;&nbsp;</U>&nbsp;Pages</P>


</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="margin: 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">1.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Names of Reporting Persons.</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">I.R.S. Identification Nos. of above persons (entities only).</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 9pt"><B>Peter Kolchinsky</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding: 7.5pt 7.5pt 6pt">&nbsp;</TD>
    <TD STYLE="padding: 7.5pt 7.5pt 6pt"><FONT STYLE="font-size: 10pt">2. </FONT></TD>
    <TD COLSPAN="2" STYLE="padding: 7.5pt 7.5pt 6pt"><FONT STYLE="font-size: 10pt">Check the Appropriate Box if a Member of a Group (See Instructions)</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 3%; padding-bottom: 7pt">&nbsp;</TD>
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 7%; padding-bottom: 7pt">&nbsp;</TD>
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 4%; padding-bottom: 7pt"><FONT STYLE="font-size: 10pt">(a)</FONT></TD>
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 86%; padding-bottom: 7pt"><FONT STYLE="font: 10pt Wingdings">&uml;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt"><FONT STYLE="font-size: 10pt">(b)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt"><FONT STYLE="font: 10pt Wingdings">&uml;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">3.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">SEC Use Only </FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">4.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Citizenship&nbsp;or&nbsp;Place&nbsp;of&nbsp;Organization&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>United States</B></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="4" STYLE="border-bottom: black 1pt solid; padding: 0; width: 15%; text-align: left; vertical-align: middle"><FONT STYLE="font-size: 10pt">Number of</FONT><BR>
<FONT STYLE="font-size: 10pt">Shares</FONT><BR>
<FONT STYLE="font-size: 10pt">Beneficially</FONT><BR>
<FONT STYLE="font-size: 10pt">Owned by</FONT><BR>
<FONT STYLE="font-size: 10pt">Each Reporting</FONT><BR>
<FONT STYLE="font-size: 10pt">Person With</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt; width: 7%"><FONT STYLE="font-size: 10pt">5.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt; width: 78%"><FONT STYLE="font-size: 10pt">Sole&nbsp;Voting&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>0&nbsp;shares</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">6.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Shared&nbsp;Voting&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>3,929,016&nbsp;shares</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">7.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Sole&nbsp;Dispositive&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>0&nbsp;shares</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">8.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Shared&nbsp;Dispositive&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>3,929,016&nbsp;shares</B></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">9.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Aggregate Amount Beneficially Owned by Each Reporting Person</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>3,929,016 shares</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">10.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Check if the Aggregate Amount in Row (9) Excludes&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT STYLE="font-family: Wingdings">&uml;</FONT></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Certain Shares (See Instructions)</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">11.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Percent of Class Represented by Amount in Row (9)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>9.9%</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">12.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Type of Reporting Person (See Instructions)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>IN</B></P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<TR>
    <TD STYLE="width: 46%; font-size: 10pt"><FONT STYLE="font-size: 10pt">CUSIP No. <B>042797209</B></FONT></TD>
    <TD STYLE="width: 22%; font-size: 12pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 32%; font-size: 10pt"><P STYLE="margin: 0pt 0; text-align: right">Page&nbsp;<U>&nbsp;&nbsp;&nbsp;<B>4</B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</U>&nbsp;of&nbsp;<U>&nbsp;&nbsp;&nbsp;<B>7</B>&nbsp;&nbsp;&nbsp;</U>&nbsp;Pages</P>


</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="margin: 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">1.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Names of Reporting Persons.</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">I.R.S. Identification Nos. of above persons (entities only).</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 9pt"><B>RA Capital Healthcare Fund, L.P.</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding: 7.5pt 7.5pt 6pt">&nbsp;</TD>
    <TD STYLE="padding: 7.5pt 7.5pt 6pt"><FONT STYLE="font-size: 10pt">2. </FONT></TD>
    <TD COLSPAN="2" STYLE="padding: 7.5pt 7.5pt 6pt"><FONT STYLE="font-size: 10pt">Check the Appropriate Box if a Member of a Group (See Instructions)</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 3%; padding-bottom: 7pt">&nbsp;</TD>
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 7%; padding-bottom: 7pt">&nbsp;</TD>
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 4%; padding-bottom: 7pt"><FONT STYLE="font-size: 10pt">(a)</FONT></TD>
    <TD STYLE="padding-right: 7.5pt; padding-left: 7.5pt; width: 86%; padding-bottom: 7pt"><FONT STYLE="font: 10pt Wingdings">&uml;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt"><FONT STYLE="font-size: 10pt">(b)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 7.5pt; padding-bottom: 7.5pt; padding-left: 7.5pt"><FONT STYLE="font: 10pt Wingdings">&uml;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">3.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">SEC Use Only </FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">4.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Citizenship&nbsp;or&nbsp;Place&nbsp;of&nbsp;Organization&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Delaware</B></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="4" STYLE="border-bottom: black 1pt solid; padding: 0; width: 15%; text-align: left; vertical-align: middle"><FONT STYLE="font-size: 10pt">Number of</FONT><BR>
<FONT STYLE="font-size: 10pt">Shares</FONT><BR>
<FONT STYLE="font-size: 10pt">Beneficially</FONT><BR>
<FONT STYLE="font-size: 10pt">Owned by</FONT><BR>
<FONT STYLE="font-size: 10pt">Each Reporting</FONT><BR>
<FONT STYLE="font-size: 10pt">Person With</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt; width: 7%"><FONT STYLE="font-size: 10pt">5.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt; width: 78%"><FONT STYLE="font-size: 10pt">Sole&nbsp;Voting&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>0&nbsp;shares</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">6.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Shared&nbsp;Voting&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>3,142,521&nbsp;shares</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">7.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Sole&nbsp;Dispositive&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>0&nbsp;shares</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">8.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">Shared&nbsp;Dispositive&nbsp;Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>3,142,521&nbsp;shares</B></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">9.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Aggregate Amount Beneficially Owned by Each Reporting Person</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>3,142,521 shares</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">10.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Check if the Aggregate Amount in Row (9) Excludes&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT STYLE="font-family: Wingdings">&uml;</FONT></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Certain Shares (See Instructions)</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">11.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Percent of Class Represented by Amount in Row (9)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>7.9%</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt"><FONT STYLE="font-size: 10pt">12.</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 7.5pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Type of Reporting Person (See Instructions)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>PN</B></P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">CUSIP No. <B>042797209</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 1.</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">(a)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Name
of Issuer:</B> Arrowhead Research Corporation (the &ldquo;Issuer&rdquo;).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">(b)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Address
of the Issuer&rsquo;s Principal Executive Offices:</B> 225 South Lake Avenue, Suite 1050, Pasadena, CA 91101.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 2.</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">(a)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Name
of Person Filing: </B> This joint statement on Schedule 13G is being filed by Peter Kolchinsky, RA Capital Management, LLC (&ldquo;Capital&rdquo;),
and RA Capital Healthcare Fund, L.P. (the &ldquo;Fund&rdquo;). Mr. Kolchinsky, Capital and the Fund are collectively referred to
herein as the &ldquo;Reporting Persons.&rdquo;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">(b)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Address
of Principal Business Office:</B> The principal business office of the Reporting Persons is c/o RA Capital Management, LLC, 20
Park Plaza, Suite 1200, Boston, MA 02116.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">(c)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Citizenship:</B>
Capital is a Massachusetts limited liability company. The Fund is a Delaware limited partnership. Mr. Kolchinsky is a United States
citizen.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">(d)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Title
and Class of Securities: </B>Common stock (&ldquo;Common Stock&rdquo;).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">(e)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>CUSIP
Number:</B> 042797209</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 3.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;If
this statement is filed pursuant to &sect;&sect;240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Not applicable.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 4.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Ownership:</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Provide the following information regarding the aggregate number
and percentage of the class of securities of the issuer identified in Item 1.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 5%; font-size: 10pt">(a)</TD>
    <TD STYLE="width: 95%">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Amount Beneficially Owned:**</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Management, LLC - 3,929,016 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">Peter Kolchinsky - 3,929,016 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Healthcare Fund, L.P. - 3,142,521 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt">(b)</TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Percent of Class:**</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Management, LLC &ndash; 9.9%</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">Peter Kolchinsky &ndash; 9.9%</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Healthcare Fund, L.P. &ndash; 7.9%</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt">(c)</TD>
    <TD STYLE="font-size: 10pt">Number of shares as to which such person has:</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>


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    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt"><TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font: 10pt Times New Roman, Times, Serif"><TR><TD STYLE="text-align: left; width: 100%">&nbsp;</TD></TR></TABLE></DIV>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">CUSIP No. <B>042797209</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 5%; font-size: 10pt"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="width: 5%; font-size: 10pt">(i)</TD>
    <TD STYLE="width: 90%">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">sole power to vote or to direct the vote **</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Management, LLC - 0 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">Peter Kolchinsky - 0 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Healthcare Fund, L.P. - 0 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt">(ii)</TD>
    <TD STYLE="font-size: 10pt">shared power to vote or to direct the vote**</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Management, LLC - 3,929,016 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">Peter Kolchinsky - 3,929,016 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Healthcare Fund, L.P. - 3,142,521 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt">(iii)</TD>
    <TD STYLE="font-size: 10pt">Sole power to dispose or to direct the disposition of**</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Management, LLC - 0 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">Peter Kolchinsky - 0 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Healthcare Fund, L.P. - 0 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt">(iv)</TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">shared power to dispose or to direct the disposition of**</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Management, LLC - 3,929,016 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">Peter Kolchinsky - 3,929,016 shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">RA Capital Healthcare Fund, L.P. - 3,142,521 shares</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">** Shares reported herein for the Reporting Persons represent
shares of Common Stock beneficially owned as set forth below and additional shares of Common Stock issuable upon the conversion
of certain shares of Series B Convertible Preferred Stock (&ldquo;Series B Shares&rdquo;) and Series C Convertible Preferred Stock
(&ldquo;Series C Shares&rdquo;) beneficially owned as set forth below. In the aggregate, the Reporting Persons own 2,991 Series
B Shares convertible into 1,634,426 shares of Common Stock and 30,000 Series C Shares convertible into 5,119,720 shares of Common
Stock. The Series B Shares and the Series C Shares may not be converted such that the number of shares of Common Stock held by
the Reporting Persons and their affiliates after such conversion exceeds 9.99% of the outstanding shares of Common Stock. Shares
reported herein for the Fund represent shares of Common Stock held of record by the Fund and additional shares of Common Stock
issuable upon the conversion of certain Series B Shares and Series C Shares held of record by the Fund. Shares reported herein
for Capital represent (a) the above-referenced shares of Common Stock and additional shares of Common Stock issuable upon the conversion
of certain Series B Shares and Series C Shares as reported for the Fund, for which the LLC serves as the sole general partner,
and (b) shares of Common Stock held in a separately managed account for which Capital serves as investment adviser, and additional
shares of Common Stock issuable upon the conversion of certain Series B Shares and Series C Shares held in such managed account.
Shares reported herein for Mr. Kolchinsky represent the above-referenced shares of Common Stock (including additional shares of
Common Stock issuable upon the exercise of certain Series B Shares and Series C Shares) reported for Capital, for which Mr. Kolchinsky
serves as the manager. Each of the Reporting Persons disclaims beneficial ownership of the shares reported herein except to the
extent of its or his pecuniary interest therein.</P>



<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">CUSIP No. <B>042797209</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 5.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Ownership
of Five Percent or Less of a Class:</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Not applicable.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 1in; text-indent: -1in"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 1in; text-indent: -1in"><B>Item 6.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Ownership
of More than Five Percent on Behalf of Another Person:</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Not applicable.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 7.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Identification
and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person:</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Not applicable.</P>



<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 8.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Identification
and Classification of Members of the Group:</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Not applicable.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 9.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Notice
of Dissolution of Group:</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Not applicable.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 10.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Certification:</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">By signing below I hereby certify that, to the best of my knowledge
and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing
or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant
in any transaction having that purpose or effect.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><U>Exhibits</U></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-indent: -0.5in">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.5in">1</TD><TD>Joint Filing Agreement by and among the Reporting Persons is incorporated herein by reference to Exhibit 1 to the
                                                         Schedule 13G filed by the Reporting Persons with the Securities and Exchange Commission on November 14<FONT STYLE="text-transform: uppercase">,
                                                         2013</FONT>.</TD></TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><I>&nbsp;</I></P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SIGNATURE</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">After reasonable inquiry and to the best
of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 60%">&nbsp;</TD>
    <TD STYLE="width: 40%"><FONT STYLE="text-transform: uppercase">Date: </FONT>February 14, 2014</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>RA CAPITAL MANAGEMENT, LLC</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid">By: /s/ Peter Kolchinsky</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>Peter Kolchinsky</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>Manager</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>PETER KOLCHINSKY</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid">/s/ Peter Kolchinsky</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>RA CAPITAL HEALTHCARE FUND, L.P.</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>By: RA Capital Management, LLC</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD STYLE="padding-left: 0.5in">General Partner</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid">By: /s/ Peter Kolchinsky</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>Peter Kolchinsky</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>Manager</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in"><FONT STYLE="text-transform: uppercase">&nbsp;</FONT></P>


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