<SEC-DOCUMENT>0001193125-15-234989.txt : 20150625
<SEC-HEADER>0001193125-15-234989.hdr.sgml : 20150625
<ACCEPTANCE-DATETIME>20150625150500
ACCESSION NUMBER:		0001193125-15-234989
CONFORMED SUBMISSION TYPE:	SC 13G
PUBLIC DOCUMENT COUNT:		2
FILED AS OF DATE:		20150625
DATE AS OF CHANGE:		20150625
GROUP MEMBERS:		HOVE, ANDERS
GROUP MEMBERS:		KOH, BONG
GROUP MEMBERS:		VENROCK HEALTHCARE CAPITAL PARTNERS II, L.P
GROUP MEMBERS:		VHCP CO-INVESTMENT HOLDINGS II, LLC
GROUP MEMBERS:		VHCP CO-INVESTMENT HOLDINGS, LLC
GROUP MEMBERS:		VHCP MANAGEMENT II, LLC
GROUP MEMBERS:		VHCP MANAGEMENT, LLC

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ARCA biopharma, Inc.
		CENTRAL INDEX KEY:			0000907654
		STANDARD INDUSTRIAL CLASSIFICATION:	IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES [2835]
		IRS NUMBER:				363855489
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-51477
		FILM NUMBER:		15951642

	BUSINESS ADDRESS:	
		STREET 1:		11080 CIRCLEPOINT ROAD
		STREET 2:		SUITE 140
		CITY:			WESTMINSTER
		STATE:			CO
		ZIP:			80020
		BUSINESS PHONE:		720-940-2200

	MAIL ADDRESS:	
		STREET 1:		11080 CIRCLEPOINT ROAD
		STREET 2:		SUITE 140
		CITY:			WESTMINSTER
		STATE:			CO
		ZIP:			80020

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NUVELO INC
		DATE OF NAME CHANGE:	20030203

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	HYSEQ INC
		DATE OF NAME CHANGE:	19970610

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			VENROCK HEALTHCARE CAPITAL PARTNERS LP
		CENTRAL INDEX KEY:			0001458177
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE

	FILING VALUES:
		FORM TYPE:		SC 13G

	BUSINESS ADDRESS:	
		STREET 1:		530 FIFTH AVENUE
		STREET 2:		22ND FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10036
		BUSINESS PHONE:		650-475-3734

	MAIL ADDRESS:	
		STREET 1:		530 FIFTH AVENUE
		STREET 2:		22ND FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10036
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13G
<SEQUENCE>1
<FILENAME>d949731dsc13g.htm
<DESCRIPTION>SCHEDULE 13G
<TEXT>
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<TITLE>SCHEDULE 13G</TITLE>
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 <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>UNITED STATES </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SECURITIES AND EXCHANGE COMMISSION </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Washington, DC 20549 </B></P> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SCHEDULE 13G
</B></P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Under the Securities Exchange Act of 1934 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>(Amendment No. &nbsp;&nbsp;&nbsp;&nbsp;)* </B></P> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:22pt; font-family:Times New Roman" ALIGN="center"><B>ARCA
biopharma, Inc. </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Name of Issuer) </B></P>
<P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Common stock </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Title of
Class of Securities) </B></P> <P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>00211Y100 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(CUSIP Number) </B></P> <P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>June 16,
2015 </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Date of Event Which Requires Filing of this Statement) </B></P>
<P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:18pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Check the appropriate box to designate the rule pursuant to which this Schedule is filed: </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT> Rule 13d-1(b) </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT> Rule 13d-1(c) </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT> Rule 13d-1(d) </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">*</TD>
<TD ALIGN="left" VALIGN="top">The remainder of this cover page shall be filled out for a reporting person&#146;s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information
which would alter disclosures provided in a prior cover page. </TD></TR></TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The information required on the remainder of this cover page
shall not be deemed to be &#147;filed&#148; for the purpose of Section 18 of the Securities Exchange Act of 1934 (&#147;Act&#148;) 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-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">SCHEDULE 13G </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>2</U> of <U>15</U> Pages</TD></TR>
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<TD WIDTH="2%"></TD>
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<TD WIDTH="5%"></TD>
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<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;1&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Names of
reporting persons.</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">I.R.S. Identification Nos. of above persons (entities only)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">Venrock Healthcare Capital Partners, L.P.</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt">&nbsp;&nbsp;2</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box if a member
of a group (see instructions)</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">(a)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT><SUP STYLE="font-size:85%; vertical-align:top">1</SUP>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;(b)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;3</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">SEC use only</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;4</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Citizenship or place of
organization</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;Delaware</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="middle" COLSPAN="3" ROWSPAN="4" ALIGN="center" STYLE="BORDER-LEFT:1px solid #000000; padding-left:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Number&nbsp;of</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">shares</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">beneficially</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">owned&nbsp;by</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">each</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">reporting</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">person</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">with</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">5&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">6</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">7</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top"><FONT STYLE="font-size:10pt">8</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;9</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt">
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Aggregate amount beneficially owned by each reporting person</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">10</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check if the aggregate amount in Row
(9) excludes certain shares (see instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;N/A</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">11</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Percent of class represented by amount
in Row (9)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;17.1%<SUP STYLE="font-size:85%; vertical-align:top">3</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">12</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Type of reporting person (see
instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;PN</P></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">1.</TD>
<TD ALIGN="left" VALIGN="top">Venrock Healthcare Capital Partners, L.P. (&#147;VHCP&#148;); Venrock Healthcare Capital Partners II, L.P. (&#147;VHCP II&#148;); VCHP Co-Investment Holdings, LLC (&#147;Co-Invest&#148;); VHCP Co-Investment Holdings II,
LLC (&#147;Co-Invest II&#148;); VCHP Management, LLC; VCHP Management II, LLC; Anders Hove and Bong Koh are members of a group for the purposes of this Schedule 13G. </TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">2.</TD>
<TD ALIGN="left" VALIGN="top">Consists of: 2,736,388 shares of common stock held directly by VHCP; 5,373,623 shares of common stock held directly by VHCP II; 500,409 shares of common stock held directly by Co-Invest; and 2,178,904 shares of common
stock held directly by Co-Invest II. </TD></TR></TABLE>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">3.</TD>
<TD ALIGN="left" VALIGN="top">This percentage is calculated based upon the number of the Issuer&#146;s total outstanding shares equal to the sum of (i) 21,198,411 shares of the Issuer&#146;s common stock outstanding as of May 11, 2015, as set forth
in the Issuer&#146;s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 12, 2015 and (ii) 42,021,579 shares of common stock issued on June&nbsp;16, 2015. </TD></TR></TABLE>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">SCHEDULE 13G </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>3</U> of <U>15</U> Pages</TD></TR>
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<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;1&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Names of
reporting persons.</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">I.R.S. Identification Nos. of above persons (entities only)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">Venrock Healthcare Capital Partners II, L.P.</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt">&nbsp;&nbsp;2</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box if a member
of a group (see instructions)</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">(a)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT><SUP STYLE="font-size:85%; vertical-align:top">1</SUP>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;(b)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;3</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">SEC use only</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;4</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Citizenship or place of
organization</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;Delaware</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="middle" COLSPAN="3" ROWSPAN="4" ALIGN="center" STYLE="BORDER-LEFT:1px solid #000000; padding-left:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Number&nbsp;of</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">shares</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">beneficially</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">owned&nbsp;by</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">each</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">reporting</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">person</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">with</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">5&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">6</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">7</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top"><FONT STYLE="font-size:10pt">8</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;9</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt">
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Aggregate amount beneficially owned by each reporting person</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">10</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check if the aggregate amount in Row
(9) excludes certain shares (see instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;N/A</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">11</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Percent of class represented by amount
in Row (9)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;17.1%<SUP STYLE="font-size:85%; vertical-align:top">3</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">12</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Type of reporting person (see
instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;PN</P></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">1.</TD>
<TD ALIGN="left" VALIGN="top">Venrock Healthcare Capital Partners, L.P. (&#147;VHCP&#148;); Venrock Healthcare Capital Partners II, L.P. (&#147;VHCP II&#148;); VCHP Co-Investment Holdings, LLC (&#147;Co-Invest&#148;); VHCP Co-Investment Holdings II,
LLC (&#147;Co-Invest II&#148;); VCHP Management, LLC; VCHP Management II, LLC; Anders Hove and Bong Koh are members of a group for the purposes of this Schedule 13G. </TD></TR></TABLE>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">2.</TD>
<TD ALIGN="left" VALIGN="top">Consists of: 2,736,388 shares of common stock held directly by VHCP; 5,373,623 shares of common stock an held directly by VHCP II; 500,409 shares of common stock held directly by Co-Invest; and 2,178,904 shares of
common stock held directly by Co-Invest II. </TD></TR></TABLE>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">3.</TD>
<TD ALIGN="left" VALIGN="top">This percentage is calculated based upon the number of the Issuer&#146;s total outstanding shares equal to the sum of (i) 21,198,411 shares of the Issuer&#146;s common stock outstanding as of May 11, 2015, as set forth
in the Issuer&#146;s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 12, 2015 and (ii) 42,021,579 shares of common stock issued on June&nbsp;16, 2015. </TD></TR></TABLE>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">SCHEDULE 13G </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>4</U> of <U>15</U> Pages</TD></TR>
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<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;1&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Names of
reporting persons.</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">I.R.S. Identification Nos. of above persons (entities only)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">VHCP Co-Investment Holdings, LLC</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt">&nbsp;&nbsp;2</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box if a member
of a group (see instructions)</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">(a)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT><SUP STYLE="font-size:85%; vertical-align:top">1</SUP>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;(b)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;3</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">SEC use only</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;4</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Citizenship or place of
organization</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;Delaware</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="middle" COLSPAN="3" ROWSPAN="4" ALIGN="center" STYLE="BORDER-LEFT:1px solid #000000; padding-left:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Number&nbsp;of</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">shares</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">beneficially</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">owned&nbsp;by</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">each</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">reporting</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">person</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">with</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">5&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">6</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">7</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top"><FONT STYLE="font-size:10pt">8</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;9</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt">
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Aggregate amount beneficially owned by each reporting person</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">10</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check if the aggregate amount in Row
(9) excludes certain shares (see instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;N/A</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">11</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Percent of class represented by amount
in Row (9)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;17.1%<SUP STYLE="font-size:85%; vertical-align:top">3</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">12</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Type of reporting person (see
instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;OO</P></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">1.</TD>
<TD ALIGN="left" VALIGN="top">Venrock Healthcare Capital Partners, L.P. (&#147;VHCP&#148;); Venrock Healthcare Capital Partners II, L.P. (&#147;VHCP II&#148;); VCHP Co-Investment Holdings, LLC (&#147;Co-Invest&#148;); VHCP Co-Investment Holdings II,
LLC (&#147;Co-Invest II&#148;); VCHP Management, LLC; VCHP Management II, LLC, Anders Hove and Bong Koh are members of a group for the purposes of this Schedule 13G. </TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">2.</TD>
<TD ALIGN="left" VALIGN="top">Consists of: 2,736,388 shares of common stock held directly by VHCP; 5,373,623 shares of common stock held directly by VHCP II; 500,409 shares of common stock held directly by Co-Invest; and 2,178,904 shares of common
stock held directly by Co-Invest II. </TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">3.</TD>
<TD ALIGN="left" VALIGN="top">This percentage is calculated based upon the number of the Issuer&#146;s total outstanding shares equal to the sum of (i) 21,198,411 shares of the Issuer&#146;s common stock outstanding as of May 11, 2015, as set forth
in the Issuer&#146;s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 12, 2015 and (ii) 42,021,579 shares of common stock issued on June&nbsp;16, 2015. </TD></TR></TABLE>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">SCHEDULE 13G </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>5</U> of <U>15</U> Pages</TD></TR>
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<TD WIDTH="2%"></TD>
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<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;1&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Names of
reporting persons.</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">I.R.S. Identification Nos. of above persons (entities only)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">VHCP Co-Investment Holdings II, LLC</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt">&nbsp;&nbsp;2</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box if a member
of a group (see instructions)</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">(a)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT><SUP STYLE="font-size:85%; vertical-align:top">1</SUP>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;(b)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;3</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">SEC use only</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;4</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Citizenship or place of
organization</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;Delaware</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="middle" COLSPAN="3" ROWSPAN="4" ALIGN="center" STYLE="BORDER-LEFT:1px solid #000000; padding-left:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Number&nbsp;of</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">shares</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">beneficially</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">owned&nbsp;by</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">each</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">reporting</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">person</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">with</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">5&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">6</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">7</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top"><FONT STYLE="font-size:10pt">8</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;9</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt">
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Aggregate amount beneficially owned by each reporting person</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">10</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check if the aggregate amount in Row
(9) excludes certain shares (see instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;N/A</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">11</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Percent of class represented by amount
in Row (9)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;17.1%<SUP STYLE="font-size:85%; vertical-align:top">3</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">12</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Type of reporting person (see
instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;OO</P></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">1.</TD>
<TD ALIGN="left" VALIGN="top">Venrock Healthcare Capital Partners, L.P. (&#147;VHCP&#148;); Venrock Healthcare Capital Partners II, L.P. (&#147;VHCP II&#148;); VCHP Co-Investment Holdings, LLC (&#147;Co-Invest&#148;); VHCP Co-Investment Holdings II,
LLC (&#147;Co-Invest II&#148;); VCHP Management, LLC; VCHP Management II, LLC; Anders Hove and Bong Koh are members of a group for the purposes of this Schedule 13G. </TD></TR></TABLE>
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<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">2.</TD>
<TD ALIGN="left" VALIGN="top">Consists of: 2,736,388 shares of common stock held directly by VHCP; 5,373,623 shares of common stock held directly by VHCP II; 500,409 shares of common stock held directly by Co-Invest; and 2,178,904 shares of common
stock held directly by Co-Invest II. </TD></TR></TABLE>
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<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">3.</TD>
<TD ALIGN="left" VALIGN="top">This percentage is calculated based upon the number of the Issuer&#146;s total outstanding shares equal to the sum of (i) 21,198,411 shares of the Issuer&#146;s common stock outstanding as of May 11, 2015, as set forth
in the Issuer&#146;s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 12, 2015 and (ii) 42,021,579 shares of common stock issued on June&nbsp;16, 2015. </TD></TR></TABLE>

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<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>6</U> of <U>15</U> Pages</TD></TR>
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<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;1&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Names of
reporting persons.</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">I.R.S. Identification Nos. of above persons (entities only)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">VHCP Management, LLC</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt">&nbsp;&nbsp;2</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box if a member
of a group (see instructions)</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">(a)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT><SUP STYLE="font-size:85%; vertical-align:top">1</SUP>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;(b)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;3</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">SEC use only</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;4</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Citizenship or place of
organization</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;Delaware</P></TD></TR>
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<TD VALIGN="middle" COLSPAN="3" ROWSPAN="4" ALIGN="center" STYLE="BORDER-LEFT:1px solid #000000; padding-left:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Number&nbsp;of</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">shares</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">beneficially</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">owned&nbsp;by</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">each</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">reporting</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">person</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">with</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">5&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">6</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">7</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top"><FONT STYLE="font-size:10pt">8</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;9</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt">
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Aggregate amount beneficially owned by each reporting person</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">10</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check if the aggregate amount in Row
(9) excludes certain shares (see instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;N/A</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">11</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Percent of class represented by amount
in Row (9)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;17.1%<SUP STYLE="font-size:85%; vertical-align:top">3</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">12</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Type of reporting person (see
instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;OO</P></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">1.</TD>
<TD ALIGN="left" VALIGN="top">Venrock Healthcare Capital Partners, L.P. (&#147;VHCP&#148;); Venrock Healthcare Capital Partners II, L.P. (&#147;VHCP II&#148;); VCHP Co-Investment Holdings, LLC (&#147;Co-Invest&#148;); VHCP Co-Investment Holdings II,
LLC (&#147;Co-Invest II&#148;); VCHP Management, LLC; VCHP Management II, LLC; Anders Hove and Bong Koh are members of a group for the purposes of this Schedule 13G. </TD></TR></TABLE>
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<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">2.</TD>
<TD ALIGN="left" VALIGN="top">Consists of: 2,736,388 shares of common stock held directly by VHCP; 5,373,623 shares of common stock held directly by VHCP II; 500,409 shares of common stock held directly by Co-Invest; and 2,178,904 shares of common
stock held directly by Co-Invest II. </TD></TR></TABLE>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">3.</TD>
<TD ALIGN="left" VALIGN="top">This percentage is calculated based upon the number of the Issuer&#146;s total outstanding shares equal to the sum of (i) 21,198,411 shares of the Issuer&#146;s common stock outstanding as of May 11, 2015, as set forth
in the Issuer&#146;s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 12, 2015 and (ii) 42,021,579 shares of common stock issued on June&nbsp;16, 2015 </TD></TR></TABLE>

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<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
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<TD VALIGN="bottom" ALIGN="right">Page <U>7</U> of <U>15</U> Pages</TD></TR>
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<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;1&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Names of
reporting persons.</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">I.R.S. Identification Nos. of above persons (entities only)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">VHCP Management II, LLC</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt">&nbsp;&nbsp;2</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box if a member
of a group (see instructions)</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">(a)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT><SUP STYLE="font-size:85%; vertical-align:top">1</SUP>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;(b)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;3</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">SEC use only</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;4</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Citizenship or place of
organization</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;Delaware</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="middle" COLSPAN="3" ROWSPAN="4" ALIGN="center" STYLE="BORDER-LEFT:1px solid #000000; padding-left:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Number&nbsp;of</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">shares</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">beneficially</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">owned&nbsp;by</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">each</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">reporting</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">person</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">with</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">5&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">6</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">7</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top"><FONT STYLE="font-size:10pt">8</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;9</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt">
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Aggregate amount beneficially owned by each reporting person</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">10</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check if the aggregate amount in Row
(9) excludes certain shares (see instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;N/A</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">11</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Percent of class represented by amount
in Row (9)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;17.1%<SUP STYLE="font-size:85%; vertical-align:top">3</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">12</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Type of reporting person (see
instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;OO</P></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">1.</TD>
<TD ALIGN="left" VALIGN="top">Venrock Healthcare Capital Partners, L.P. (&#147;VHCP&#148;); Venrock Healthcare Capital Partners II, L.P. (&#147;VHCP II&#148;); VCHP Co-Investment Holdings, LLC (&#147;Co-Invest&#148;); VHCP Co-Investment Holdings II,
LLC (&#147;Co-Invest II&#148;); VCHP Management, LLC; VCHP Management II, LLC; Anders Hove and Bong Koh are members of a group for the purposes of this Schedule 13G. </TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">2.</TD>
<TD ALIGN="left" VALIGN="top">Consists of: 2,736,388 shares of common stock held directly by VHCP; 5,373,623 shares of common stock held directly by VHCP II; 500,409 shares of common stock held directly by Co-Invest; and 2,178,904 shares of common
stock held directly by Co-Invest II. </TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">3.</TD>
<TD ALIGN="left" VALIGN="top">This percentage is calculated based upon the number of the Issuer&#146;s total outstanding shares equal to the sum of (i) 21,198,411 shares of the Issuer&#146;s common stock outstanding as of May 11, 2015, as set forth
in the Issuer&#146;s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 12, 2015 and (ii) 42,021,579 shares of common stock issued on June&nbsp;16, 2015. </TD></TR></TABLE>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">SCHEDULE 13G </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>8</U> of <U>15</U> Pages</TD></TR>
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<TD WIDTH="2%"></TD>
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<TD WIDTH="5%"></TD>
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<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;1&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Names of
reporting persons.</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">I.R.S. Identification Nos. of above persons (entities only)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">Koh, Bong</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt">&nbsp;&nbsp;2</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box if a member
of a group (see instructions)</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">(a)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT><SUP STYLE="font-size:85%; vertical-align:top">1</SUP>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;(b)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;3</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">SEC use only</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;4</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Citizenship or place of
organization</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;United States</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="middle" COLSPAN="3" ROWSPAN="4" ALIGN="center" STYLE="BORDER-LEFT:1px solid #000000; padding-left:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Number&nbsp;of</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">shares</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">beneficially</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">owned&nbsp;by</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">each</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">reporting</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">person</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">with</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">5&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">6</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">7</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top"><FONT STYLE="font-size:10pt">8</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;9</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt">
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Aggregate amount beneficially owned by each reporting person</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">10</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check if the aggregate amount in Row
(9) excludes certain shares (see instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;N/A</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">11</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Percent of class represented by amount
in Row (9)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;17.1%<SUP STYLE="font-size:85%; vertical-align:top">3</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">12</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Type of reporting person (see
instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;IN</P></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">1.</TD>
<TD ALIGN="left" VALIGN="top">Venrock Healthcare Capital Partners, L.P. (&#147;VHCP&#148;); Venrock Healthcare Capital Partners II, L.P. (&#147;VHCP II&#148;); VCHP Co-Investment Holdings, LLC (&#147;Co-Invest&#148;); VHCP Co-Investment Holdings II,
LLC (&#147;Co-Invest II&#148;); VCHP Management, LLC; VCHP Management II, LLC; Anders Hove and Bong Koh are members of a group for the purposes of this Schedule 13G. </TD></TR></TABLE>
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<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">2.</TD>
<TD ALIGN="left" VALIGN="top">Consists of: 2,736,388 shares of common stock held directly by VHCP; 5,373,623 shares of common stock held directly by VHCP II; 500,409 shares of common stock held directly by Co-Invest; and 2,178,904 shares of common
stock held directly by Co-Invest II. </TD></TR></TABLE>
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<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">3.</TD>
<TD ALIGN="left" VALIGN="top">This percentage is calculated based upon the number of the Issuer&#146;s total outstanding shares equal to the sum of (i) 21,198,411 shares of the Issuer&#146;s common stock outstanding as of May 11, 2015, as set forth
in the Issuer&#146;s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 12, 2015 and (ii) 42,021,579 shares of common stock issued on June&nbsp;16, 2015. </TD></TR></TABLE>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">SCHEDULE 13G </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>9</U> of <U>15</U> Pages</TD></TR>
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<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;1&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Names of
reporting persons.</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">I.R.S. Identification Nos. of above persons (entities only)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">Hove, Anders</P></TD></TR>
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<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt">&nbsp;&nbsp;2</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box if a member
of a group (see instructions)</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">(a)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT><SUP STYLE="font-size:85%; vertical-align:top">1</SUP>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;(b)&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;3</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">SEC use only</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:1pt">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;4</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Citizenship or place of
organization</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;United States</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="middle" COLSPAN="3" ROWSPAN="4" ALIGN="center" STYLE="BORDER-LEFT:1px solid #000000; padding-left:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Number&nbsp;of</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">shares</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">beneficially</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">owned&nbsp;by</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">each</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">reporting</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">person</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">with</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">5&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">6</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared voting power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-size:10pt">7</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Sole dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;0</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top"><FONT STYLE="font-size:10pt">8</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000"></TD>
<TD VALIGN="top" STYLE="BORDER-RIGHT:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Shared dispositive power</P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">&nbsp;&nbsp;9</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-TOP:1px solid #000000; BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt">
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Aggregate amount beneficially owned by each reporting person</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;10,789,324<SUP STYLE="font-size:85%; vertical-align:top">2</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">10</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check if the aggregate amount in Row
(9) excludes certain shares (see instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;N/A</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">11</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Percent of class represented by amount
in Row (9)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;17.1%<SUP STYLE="font-size:85%; vertical-align:top">3</SUP></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:12pt">
<TD VALIGN="top" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-left:8pt"><FONT STYLE="font-size:10pt">12</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-BOTTOM:1px solid #000000"></TD>
<TD VALIGN="top" COLSPAN="5" STYLE="BORDER-RIGHT:1px solid #000000; BORDER-BOTTOM:1px solid #000000; padding-right:8pt"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Type of reporting person (see
instructions)</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:12pt; font-family:Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;IN</P></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">1.</TD>
<TD ALIGN="left" VALIGN="top">Venrock Healthcare Capital Partners, L.P. (&#147;VHCP&#148;); Venrock Healthcare Capital Partners II, L.P. (&#147;VHCP II&#148;); VCHP Co-Investment Holdings, LLC (&#147;Co-Invest&#148;); VHCP Co-Investment Holdings II,
LLC (&#147;Co-Invest II&#148;); VCHP Management, LLC; VCHP Management II, LLC; Anders Hove and Bong Koh are members of a group for the purposes of this Schedule 13G. </TD></TR></TABLE>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">2.</TD>
<TD ALIGN="left" VALIGN="top">Consists of: 2,736,388 shares of common stock held directly by VHCP; 5,373,623 shares of common stock held directly by VHCP II; 500,409 shares of common stock held directly by Co-Invest; and 2,178,904 shares of common
stock held directly by Co-Invest II. </TD></TR></TABLE>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">3.</TD>
<TD ALIGN="left" VALIGN="top">This percentage is calculated based upon the number of the Issuer&#146;s total outstanding shares equal to the sum of (i) 21,198,411 shares of the Issuer&#146;s common stock outstanding as of May 11, 2015, as set forth
in the Issuer&#146;s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 12, 2015 and (ii) 42,021,579 shares of common stock issued on June&nbsp;16, 2015. </TD></TR></TABLE>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">SCHEDULE 13G </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
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<TD VALIGN="bottom" ALIGN="right">Page <U>
10</U>
 of <U>15</U> Pages</TD></TR></TABLE> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Introductory Note: This Schedule 13G is filed on behalf of Venrock Healthcare Capital Partners, L.P., a
limited partnership organized under the laws of the state of Delaware, Venrock Capital Partners II, L.P., a limited partnership organized under the laws of the state of Delaware, VCHP Co-Investment Holdings, LLC., a limited liability company
organized under the laws of the state of Delaware, VHCP Co-Investment Holdings II, LLC, a limited liability company organized under the laws of the state of Delaware, VCHP Management, LLC, a limited liability company organized under the laws of the
state of Delaware, VCHP Management II, LLC, a limited liability company organized under the laws of the state of Delaware, Anders Hove and Bong Koh in respect of the shares of common stock of ARCA biopharma, Inc. </P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;1. </B></P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">(a)</TD>
<TD ALIGN="left" VALIGN="top"><B>Name of Issuer:</B> </TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">ARCA biopharma, Inc. </P>
<P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(b)</TD>
<TD ALIGN="left" VALIGN="top"><B>Address of Issuer&#146;s Principal Executive Offices:</B> </TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">11080 CirclePoint Road, Suite 140
</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Westminster, CO 80020 </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;2.
</B></P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(a)</TD>
<TD ALIGN="left" VALIGN="top"><B>Name of Persons Filing:</B> </TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners, L.P. </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners II, L.P. </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings, LLC </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings II, LLC </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">VHCP Management, LLC </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">VHCP
Management II, LLC </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Anders Hove </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Bong Koh </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(b)</TD>
<TD ALIGN="left" VALIGN="top"><B>Address of Principal Business Office or, if none, Residence:</B> </TD></TR></TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="84%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


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<TD WIDTH="33%"></TD>
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<TD VALIGN="top">New York Office</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Palo Alto Office</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Cambridge Office</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">530 Fifth Avenue</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">3340 Hillview Avenue</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">55 Cambridge Parkway</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">22<SUP STYLE="font-size:85%; vertical-align:top">nd</SUP> Floor</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Palo Alto, CA 94304</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Suite 100</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">New York, NY 10036</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Cambridge MA, 02142</TD></TR>
</TABLE>

<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">



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<TR>
<TD WIDTH="50%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="49%"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>
11</U>
 of <U>15</U> Pages</TD></TR></TABLE> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>

<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(c)</TD>
<TD ALIGN="left" VALIGN="top"><B>Citizenship:</B> </TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">All entities are organized in Delaware. The individuals are both United
States citizens. </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(d)</TD>
<TD ALIGN="left" VALIGN="top"><B>Title of Class of Securities:</B> </TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Common Stock </P>
<P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(e)</TD>
<TD ALIGN="left" VALIGN="top"><B>CUSIP Number:</B> </TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">00211Y100 </P>
<P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;3:</B></TD>
<TD ALIGN="left" VALIGN="top"><B>If this statement is filed pursuant to &#167;&#167;240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a: </B></TD></TR></TABLE>
<P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Not applicable. </P>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">SCHEDULE 13G </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">

<TR>
<TD WIDTH="50%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="49%"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>
12</U>
 of <U>15</U> Pages</TD></TR></TABLE> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>

<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;4.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Ownership: </B></TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%">&nbsp;</TD>
<TD WIDTH="5%" VALIGN="top" ALIGN="left">(a)</TD>
<TD ALIGN="left" VALIGN="top">Amount beneficially owned as of June&nbsp;16, 2015: </TD></TR></TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="68%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


<TR>
<TD WIDTH="85%"></TD>
<TD VALIGN="bottom" WIDTH="5%"></TD>
<TD></TD>
<TD></TD>
<TD></TD></TR>


<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners II, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Anders Hove</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Bong Koh</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%">&nbsp;</TD>
<TD WIDTH="5%" VALIGN="top" ALIGN="left">(b)</TD>
<TD ALIGN="left" VALIGN="top">Percent of class as of June 16, 2015: </TD></TR></TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="68%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


<TR>
<TD WIDTH="92%"></TD>
<TD VALIGN="bottom" WIDTH="5%"></TD>
<TD></TD>
<TD></TD>
<TD></TD></TR>

<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">17.1</TD>
<TD NOWRAP VALIGN="bottom">%&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners II, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">17.1</TD>
<TD NOWRAP VALIGN="bottom">%&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">17.1</TD>
<TD NOWRAP VALIGN="bottom">%&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">17.1</TD>
<TD NOWRAP VALIGN="bottom">%&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">17.1</TD>
<TD NOWRAP VALIGN="bottom">%&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">17.1</TD>
<TD NOWRAP VALIGN="bottom">%&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Anders Hove</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">17.1</TD>
<TD NOWRAP VALIGN="bottom">%&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Bong Koh</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">17.1</TD>
<TD NOWRAP VALIGN="bottom">%&nbsp;</TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%">&nbsp;</TD>
<TD WIDTH="5%" VALIGN="top" ALIGN="left">(c)</TD>
<TD ALIGN="left" VALIGN="top">Number of shares to which the person has as of June 16, 2015: </TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="13%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(i)</TD>
<TD ALIGN="left" VALIGN="top">Sole power to vote or to direct the vote: </TD></TR></TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="68%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


<TR>
<TD WIDTH="95%"></TD>
<TD VALIGN="bottom" WIDTH="4%"></TD>
<TD></TD>
<TD></TD>
<TD></TD></TR>

<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners II, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Anders Hove</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Bong Koh</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
</TABLE>

<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">



<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">

<TR>
<TD WIDTH="50%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="49%"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>
13</U>
 of <U>15</U> Pages</TD></TR></TABLE> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>

<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="13%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(ii)</TD>
<TD ALIGN="left" VALIGN="top">Shared power to vote or to direct the vote: </TD></TR></TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="68%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


<TR>
<TD WIDTH="85%"></TD>
<TD VALIGN="bottom" WIDTH="5%"></TD>
<TD></TD>
<TD></TD>
<TD></TD></TR>


<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners II, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Anders Hove</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Bong Koh</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="13%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(iii)</TD>
<TD ALIGN="left" VALIGN="top">Sole power to dispose or to direct the disposition of: </TD></TR></TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="68%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


<TR>
<TD WIDTH="95%"></TD>
<TD VALIGN="bottom" WIDTH="4%"></TD>
<TD></TD>
<TD></TD>
<TD></TD></TR>

<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners II, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Anders Hove</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Bong Koh</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">0</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;&nbsp;</TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="13%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(iv)</TD>
<TD ALIGN="left" VALIGN="top">Shared power to dispose or to direct the disposition of: </TD></TR></TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="68%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


<TR>
<TD WIDTH="85%"></TD>
<TD VALIGN="bottom" WIDTH="5%"></TD>
<TD></TD>
<TD></TD>
<TD></TD></TR>

<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Venrock Healthcare Capital Partners II, L.P.</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Co-Investment Holdings II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">VHCP Management II, LLC</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff" STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Anders Hove</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Bong Koh</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top"></SUP>&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10,789,324<SUP STYLE="font-size:85%; vertical-align:top"></SUP></TD>
<TD NOWRAP VALIGN="bottom"><SUP STYLE="font-size:85%; vertical-align:top">(1)</SUP>&nbsp;</TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(1)</TD>
<TD ALIGN="left" VALIGN="top">These shares are owned directly as follows: 2,736,388 shares of common stock are owned by Venrock Healthcare Capital Partners, L.P. (&#147;VHCP&#148;); 5,373,623 shares of common stock are owned by Venrock Healthcare
Capital Partners II, L.P. (&#147;VHCP II&#148;); 500,409 shares of common stock are owned by VHCP Co-Investment Holdings, LLC (&#147;Co-Invest&#148;); and 2,178,904 shares of common stock are owned by VHCP Co-Investment Holdings II, LLC
(&#147;Co-Invest II&#148;). VHCP Management, LLC is the general partner of VHCP and the manager of Co-Invest. VHCP Management II, LLC is the general partner of VHCP II and the manager of Co-Invest II. Messrs. Hove and Koh are the managing members of
VHCP Management, LLC and VHCP Management II, LLC. </TD></TR></TABLE> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;5.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Ownership of Five Percent or Less of Class: </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">If this statement is being filed to report the fact that as
of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT> </P>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">SCHEDULE 13G </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>
14</U>
 of <U>15</U> Pages</TD></TR></TABLE> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>

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<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;6.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Ownership of More than Five Percent on Behalf of Another Person: </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Not applicable. </P>
<P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;7.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company: </B></TD></TR></TABLE>
<P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Not applicable. </P> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;8.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Identification and Classification of Members of the Group: </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Not applicable. </P>
<P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;9.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Notice of Dissolution of Group: </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">Not applicable. </P>
<P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;10.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Certification: </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">By signing below I 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>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">SCHEDULE 13G </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="49%"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">CUSIP&nbsp;No. <U>00211Y100</U></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom" ALIGN="right">Page <U>
15</U>
 of <U>15</U> Pages</TD></TR></TABLE> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>SIGNATURE </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:8%; font-size:10pt; font-family:Times New Roman">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="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Date: June&nbsp;25, 2015 </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="bottom" WIDTH="1%"></TD>
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<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="5"><B>Venrock Healthcare Capital Partners, L.P.</B></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="5"><B>Venrock Healthcare Capital Partners II, L.P.</B></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">VHCP Management, LLC</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">VHCP Management II, LLC</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">Manager</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">General Partner</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16" COLSPAN="5"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="6"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="5"><B>VHCP Co-Investment Holdings, LLC</B></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="5"><B>VHCP Co-Investment Holdings II, LLC</B></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">VHCP Management, LLC</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">VHCP Management II, LLC</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">Manager</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">General Partner</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16" COLSPAN="5"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="6"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="5"><B>VHCP Management, LLC</B></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="5"><B>VHCP Management II, LLC</B></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16" COLSPAN="5"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="6"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="5"><B>Anders Hove</B></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="5"><B>Bong Koh</B></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">David L. Stepp, as attorney-in-fact</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">David L. Stepp, as attorney-in-fact</TD></TR>
</TABLE>

<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>EXHIBITS </B></P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">A:</TD>
<TD ALIGN="left" VALIGN="top">Joint Filing Agreement </TD></TR></TABLE>
 <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>

</BODY></HTML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-99.A
<SEQUENCE>2
<FILENAME>d949731dex99a.htm
<DESCRIPTION>EX-99.A
<TEXT>
<HTML><HEAD>
<TITLE>EX-99.A</TITLE>
</HEAD>
 <BODY BGCOLOR="WHITE">

 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B><U>EXHIBIT A </U></B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">JOINT FILING AGREEMENT </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">In
accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the undersigned agree to the joint filing on behalf of each of them of a statement on Schedule 13G (including amendments thereto) with respect to the Common Stock
of ARCA biopharma, Inc. and further agree that this agreement be included as an exhibit to such filing. Each party to the agreement expressly authorizes each other party to file on its behalf any and all amendments to such statement. Each party to
this agreement agrees that this joint filing agreement may be signed in counterparts. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">In evidence whereof, the undersigned have caused
this Agreement to be executed on their behalf this 25<SUP STYLE="font-size:85%; vertical-align:top">th</SUP> day of June, 2015. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">


<TR>
<TD WIDTH="2%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="4%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="39%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="4%"></TD>
<TD VALIGN="bottom"></TD>
<TD WIDTH="2%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="4%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="39%"></TD></TR>


<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="5"><B>Venrock Healthcare Capital Partners, L.P.</B></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="5"><B>Venrock Healthcare Capital Partners II, L.P.</B></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">VHCP Management, LLC</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">VHCP Management II, LLC</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">Manager</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">General Partner</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16" COLSPAN="5"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="6"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="5"><B>VHCP Co-Investment Holdings, LLC</B></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="5"><B>VHCP Co-Investment Holdings II, LLC</B></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">VHCP Management, LLC</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">VHCP Management II, LLC</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">Manager</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3">General Partner</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16" COLSPAN="5"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="6"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="5"><B>VHCP Management, LLC</B></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="5"><B>VHCP Management II, LLC</B></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">David L. Stepp</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Its:</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Authorized Signatory</TD>
<TD VALIGN="bottom"></TD>
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<TD VALIGN="top">Its:</TD>
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<TD VALIGN="top">Authorized Signatory</TD></TR>
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<TD VALIGN="top" COLSPAN="5"><B>Anders Hove</B></TD>
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<TD VALIGN="top" COLSPAN="5"><B>Bong Koh</B></TD></TR>
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<TD VALIGN="top">By:</TD>
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<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD>
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<TD VALIGN="top">By:</TD>
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<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ David L. Stepp</P></TD></TR>
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<TD VALIGN="top" COLSPAN="3">David L. Stepp, as attorney-in-fact</TD>
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<TD VALIGN="top" COLSPAN="3">David L. Stepp, as attorney-in-fact</TD></TR>
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