<SEC-DOCUMENT>0001144204-17-009047.txt : 20170214
<SEC-HEADER>0001144204-17-009047.hdr.sgml : 20170214
<ACCEPTANCE-DATETIME>20170214173311
ACCESSION NUMBER:		0001144204-17-009047
CONFORMED SUBMISSION TYPE:	SC 13G/A
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20170214
DATE AS OF CHANGE:		20170214
GROUP MEMBERS:		PETER KOLCHINSKY

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/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-51477
		FILM NUMBER:		17610790

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

	FILING VALUES:
		FORM TYPE:		SC 13G/A

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

	MAIL ADDRESS:	
		STREET 1:		20 PARK PLAZA, SUITE 1200
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13G/A
<SEQUENCE>1
<FILENAME>v459264_sc13ga.htm
<DESCRIPTION>SC 13G/A
<TEXT>
<HTML>
<HEAD>
     <TITLE></TITLE>
</HEAD>
<BODY STYLE="font: 10pt Times New Roman, Times, Serif">

<P STYLE="margin: 0">&nbsp;</P>

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

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

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

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

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

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

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Name of Issuer)</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Common Stock, par value $0.001 per share</B></P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Title of Class of Securities)</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>00211Y407</B></P>

<!-- Field: Rule-Page --><DIV ALIGN="LEFT" STYLE="margin-top: 0; margin-bottom: 0"><DIV STYLE="font-size: 1pt; border-top: Black 1pt solid; width: 100%">&nbsp;</DIV></DIV><!-- Field: /Rule-Page -->

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(CUSIP Number)</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>December 31, 2016</B></P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Date of Event Which Requires Filing of
this Statement)</P>

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

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

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

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0.25in"></TD><TD STYLE="width: 0.25in; text-align: left"><FONT STYLE="font-family: Wingdings; font-size: 10pt">x</FONT></TD><TD STYLE="text-align: justify">Rule
                                         13d-1(b)</TD>
</TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0.25in"></TD><TD STYLE="width: 0.25in; text-align: left"><FONT STYLE="font-family: Wingdings; font-size: 10pt">&uml;</FONT></TD><TD STYLE="text-align: justify">Rule
                                         13d-1(c)</TD>
</TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0.25in"></TD><TD STYLE="width: 0.25in; text-align: left"><FONT STYLE="font-family: Wingdings; font-size: 10pt">&uml;</FONT></TD><TD STYLE="text-align: justify">Rule
                                         13d-1(d)</TD>
</TR></TABLE>

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

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

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

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

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


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    <!-- Field: /Page -->

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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR>
    <TD STYLE="width: 70%; padding: 0; font-size: 10pt; text-indent: 0"><FONT STYLE="font-size: 10pt">CUSIP No. </FONT><B>00211Y407</B></TD>
    <TD STYLE="width: 30%; padding: 0; font-size: 10pt; text-align: center; text-indent: 0"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD></TR>
</TABLE>


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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: top">
    <TD STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt">&nbsp;</td>
    <TD STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">1.</font></td>
    <TD STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Names of Reporting Persons.<br>
        I.R.S. Identification Nos. of above persons (entities only).</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><b>RA Capital Management, LLC</b></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in; text-indent: 0.5in"><b>&nbsp;</b></P></td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt">&nbsp;</td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">2. </font></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">Check the Appropriate Box if a Member of a Group (See Instructions)</font></td></tr>
<tr style="vertical-align: top">
    <TD STYLE="width: 5%; padding-top: 0; padding-bottom: 0">&nbsp;</td>
    <TD STYLE="width: 6%; padding-top: 0; padding-bottom: 0">&nbsp;</td>
    <TD STYLE="width: 89%; padding-top: 0; padding-bottom: 0"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">(a)&nbsp;&nbsp;&nbsp;</font><font style="font-family: Wingdings; font-size: 10pt">&uml;</font></td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 0; padding-bottom: 0">&nbsp;</td>
    <TD STYLE="padding-top: 0; padding-bottom: 0">&nbsp;</td>
    <TD STYLE="padding-top: 0; padding-bottom: 0"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">(b)&nbsp;&nbsp;&nbsp;</font><font style="font-family: Wingdings; font-size: 10pt">&uml;</font></td></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt">&nbsp;</td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">3.</font></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">SEC Use Only </font></td></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt">&nbsp;</td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">4.</font></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">Citizenship or Place of Organization&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<b>Massachusetts</b></font></td></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0; padding-right: 0">&nbsp;</td></tr>
</table>




<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: top">
    <TD ROWSPAN="7" STYLE="width: 17%; padding-top: 3pt; padding-bottom: 0; text-align: left; vertical-align: middle"><FONT STYLE="font-size: 10pt">Number of</FONT><br>
    <FONT STYLE="font-size: 10pt">Shares</FONT><br>
    <FONT STYLE="font-size: 10pt">Beneficially</FONT><br>
    <FONT STYLE="font-size: 10pt">Owned by</FONT><br>
    <FONT STYLE="font-size: 10pt">Each Reporting</FONT><br>
    <FONT STYLE="font-size: 10pt">Person With</FONT></td>
    <TD STYLE="width: 5%; padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">5.</FONT></td>
    <TD STYLE="width: 25%; padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">Sole Voting Power </FONT></TD>
    <TD STYLE="width: 53%; padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt"><B>0 shares</B></FONT></TD></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-bottom: 0">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">6.</FONT></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">Shared Voting Power</FONT></TD>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt"> <B>556,735<FONT STYLE="font-family: Times New Roman, Times, Serif"><SUP>1 </SUP></FONT>shares</B></FONT></TD></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-bottom: 0">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">7.</FONT></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">Sole Dispositive Power </FONT></TD>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt"><B>0 shares</B></FONT></TD></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-bottom: 0">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">8.</FONT></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">Shared Dispositive Power </FONT></TD>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt"><B>556,735<SUP>1</SUP> shares </B></FONT></TD></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="4" STYLE="padding-top: 3pt; padding-bottom: 0">&nbsp;</td></tr>
</table>


<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD STYLE="border-top: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt">&nbsp;</TD>
    <TD STYLE="border-top: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">9.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-top: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Aggregate Amount Beneficially Owned by Each Reporting Person</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>556,735<SUP>1</SUP> shares </B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="4" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 5%; padding-top: 3pt; padding-bottom: 3pt">&nbsp;</TD>
    <TD STYLE="width: 6%; padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">10.</FONT></TD>
    <TD STYLE="width: 69%; padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Check
if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)</FONT></TD>
    <TD STYLE="width: 20%; padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Wingdings; font-size: 10pt">&uml;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="4" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt">&nbsp;</TD>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">11.</FONT></TD>
    <TD COLSPAN="2" STYLE="padding-top: 3pt; padding-bottom: 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Percent of Class Represented by Amount in Row (9)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>5.9%<SUP>2 </SUP></B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="4" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt">&nbsp;</TD>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">12.</FONT></TD>
    <TD COLSPAN="2" STYLE="padding-top: 3pt; padding-bottom: 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Type of Reporting Person (See Instructions)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>IA</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="4" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</TD></TR>
</TABLE>


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

<!-- Field: Rule-Page --><DIV ALIGN="LEFT" STYLE="margin-top: 0; margin-bottom: 3pt"><DIV STYLE="font-size: 1pt; border-top: Black 1pt solid; width: 25%">&nbsp;</DIV></DIV><!-- Field: /Rule-Page -->

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Times New Roman, Times, Serif"><SUP>1
</SUP></FONT>The shares reported herein for the Reporting Person represent (i) 232,245 shares of the Issuer&rsquo;s Common Stock
beneficially owned and (ii) 324,490 shares of the Issuer&rsquo;s Common Stock the reporting person has the right to acquire through
the exercise of warrants dated June 16, 2015 (&ldquo;Warrant Shares&rdquo;).</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Times New Roman, Times, Serif"><SUP>2
</SUP></FONT>The percentage calculation assumes (i) 9,082,366 outstanding shares of Common Stock of the Issuer, based on the Issuer&rsquo;s
Form 10-Q as filed with the Securities and Exchange Commission (&ldquo;SEC&rdquo;) on November 14, 2016, plus (ii) 324,490 shares
of the Issuer&rsquo;s Common Stock the reporting person has the right to acquire through the exercise of Warrant Shares.</P>



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


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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR>
    <TD STYLE="width: 70%; padding: 0; font-size: 10pt; text-indent: 0"><FONT STYLE="font-size: 10pt">CUSIP No. </FONT><B>00211Y407</B></TD>
    <TD STYLE="width: 30%; padding: 0; font-size: 10pt; text-align: center; text-indent: 0"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: top">
    <TD STYLE="border-top: Black 1pt solid; padding-top: 3pt; padding-bottom: 3pt">&nbsp;</td>
    <TD STYLE="border-top: Black 1pt solid; padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">1.</font></td>
    <TD STYLE="border-top: Black 1pt solid; padding-top: 3pt; padding-bottom: 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Names of Reporting Persons.<br>
        I.R.S. Identification Nos. of above persons (entities only).</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><b>Peter Kolchinsky</b></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in; text-indent: 0.5in"><b>&nbsp;</b></P></td></tr>
<tr style="vertical-align: top">
    <TD STYLE="border-top: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt">&nbsp;</td>
    <TD STYLE="border-top: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">2. </font></td>
    <TD STYLE="border-top: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">Check the Appropriate Box if a Member of a Group (See Instructions)</font></td></tr>
<tr style="vertical-align: top">
    <TD STYLE="width: 5%; padding-top: 0; padding-bottom: 0">&nbsp;</td>
    <TD STYLE="width: 6%; padding-top: 0; padding-bottom: 0">&nbsp;</td>
    <TD STYLE="width: 89%; padding-top: 0; padding-bottom: 0"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">(a)&nbsp;&nbsp;&nbsp;</font><font style="font-family: Wingdings; font-size: 10pt">&uml;</font></td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 0; padding-bottom: 0">&nbsp;</td>
    <TD STYLE="padding-top: 0; padding-bottom: 0">&nbsp;</td>
    <TD STYLE="padding-top: 0; padding-bottom: 0"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">(b)&nbsp;&nbsp;&nbsp;</font><font style="font-family: Wingdings; font-size: 10pt">&uml;</font></td></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt">&nbsp;</td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">3.</font></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">SEC Use Only </font></td></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt">&nbsp;</td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">4.</font></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><font style="font-family: Times New Roman, Times, Serif; font-size: 10pt">Citizenship or Place of Organization&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<b>United States</b></font></td></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="padding-top: 0; padding-bottom: 0">&nbsp;</td></tr>
</table>




<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: top">
    <TD ROWSPAN="7" STYLE="width: 17%; border-top: Black 1pt solid; padding-top: 3pt; padding-bottom: 0; text-align: left; vertical-align: middle"><FONT STYLE="font-size: 10pt">Number of</FONT><br>
    <FONT STYLE="font-size: 10pt">Shares</FONT><br>
    <FONT STYLE="font-size: 10pt">Beneficially</FONT><br>
    <FONT STYLE="font-size: 10pt">Owned by</FONT><br>
    <FONT STYLE="font-size: 10pt">Each Reporting</FONT><br>
    <FONT STYLE="font-size: 10pt">Person With</FONT></td>
    <TD STYLE="width: 5%; border-top: Black 1pt solid; padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">5.</FONT></td>
    <TD STYLE="width: 25%; border-top: Black 1pt solid; padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">Sole Voting Power </FONT></TD>
    <TD STYLE="width: 53%; border-top: Black 1pt solid; padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt"><B>0 shares</B></FONT></TD></tr>
<tr style="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-bottom: 0">&nbsp;</td>
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-bottom: 0">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">6.</FONT></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">Shared Voting Power </FONT></TD>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt"><B>556,735<FONT STYLE="font-family: Times New Roman, Times, Serif"><SUP>1 </SUP></FONT>shares</B></FONT></TD></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-bottom: 0">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">7.</FONT></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">Sole Dispositive Power</FONT></TD>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt"> <B>0 shares</B></FONT></TD></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-bottom: 0">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">8.</FONT></td>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">Shared Dispositive Power </FONT></TD>
    <TD STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt"><B>556,735<SUP>1</SUP> shares</B></FONT></TD></tr>
<tr style="vertical-align: top">
    <TD COLSPAN="4" STYLE="padding-top: 3pt; padding-bottom: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></td></tr>
</table>


<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD STYLE="border-top: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt">&nbsp;</TD>
    <TD STYLE="border-top: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">9.</FONT></TD>
    <TD COLSPAN="2" STYLE="border-top: black 1pt solid; padding-top: 3pt; padding-bottom: 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Aggregate Amount Beneficially Owned by Each Reporting Person</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>556,735<SUP>1</SUP> shares</B></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="4" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 5%; padding-top: 3pt; padding-bottom: 3pt">&nbsp;</TD>
    <TD STYLE="width: 6%; padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">10.</FONT></TD>
    <TD STYLE="width: 69%; padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Check
if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)</FONT></TD>
    <TD STYLE="width: 20%; padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Wingdings; font-size: 10pt">&uml;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="4" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt">&nbsp;</TD>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">11.</FONT></TD>
    <TD COLSPAN="2" STYLE="padding-top: 3pt; padding-bottom: 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Percent of Class Represented by Amount in Row (9)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>5.9%<SUP>2</SUP></B> &nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="4" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt">&nbsp;</TD>
    <TD STYLE="padding-top: 3pt; padding-bottom: 3pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">12.</FONT></TD>
    <TD COLSPAN="2" STYLE="padding-top: 3pt; padding-bottom: 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Type of Reporting Person (See Instructions)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.25in"><B>IN</B> &nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid; padding-top: 0; padding-bottom: 0">&nbsp;</TD></TR>
</TABLE>


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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Times New Roman, Times, Serif"><SUP>1
</SUP></FONT>The shares reported herein for the Reporting Person represent (i) 232,245 shares of the Issuer&rsquo;s Common Stock
beneficially owned and (ii) 324,490 shares of the Issuer&rsquo;s Common Stock the reporting person has the right to acquire through
the exercise of warrants dated June 16, 2015 (&ldquo;Warrant Shares&rdquo;).</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Times New Roman, Times, Serif"><SUP>2
</SUP></FONT>The percentage calculation assumes (i) 9,082,366 outstanding shares of Common Stock of the Issuer, based on the Issuer&rsquo;s
Form 10-Q as filed with the Securities and Exchange Commission (&ldquo;SEC&rdquo;) on November 14, 2016, plus (ii) 324,490 shares
of the Issuer&rsquo;s Common Stock the reporting person has the right to acquire through the exercise of Warrant Shares.</P>



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


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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR>
    <TD STYLE="width: 70%; padding: 0; font-size: 10pt; text-indent: 0"><FONT STYLE="font-size: 10pt">CUSIP No. </FONT><B>00211Y407</B></TD>
    <TD STYLE="width: 30%; padding: 0; font-size: 10pt; text-align: center; text-indent: 0"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(a)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Name of Issuer:</B> ARCA biopharma,
Inc. (the &ldquo;Issuer&rdquo;).</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(b)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Address of the Issuer&rsquo;s
Principal Executive Offices:</B> 11080 CirclePoint Road, Suite 140, Westminster, CO 80020.</P>

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0in">(a)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Name of Person
Filing: </B>This joint statement on Schedule 13G is being filed by RA Capital Management, LLC (&ldquo;Capital&rdquo;) and Peter
Kolchinsky. Capital and Mr. Kolchinsky are collectively referred to herein as the &ldquo;Reporting Persons.&rdquo; Capital is
the general partner of the RA Capital Healthcare Fund, L.P. (the &ldquo;Fund&rdquo;) and serves as investment adviser for a separately
managed account (the &ldquo;Account&rdquo;). Mr. Kolchinsky is the manager of Capital. As the investment adviser to the Fund and
the Account, Capital may be deemed a beneficial owner, for purposes of Section 13(d) of the Securities Exchange Act of 1934 (the
&ldquo;Act&rdquo;), of any securities of the Issuer owned by the Fund or the Account. As the manager of Capital, Mr. Kolchinsky
may be deemed a beneficial owner, for purposes of Section 13(d) of the Act, of any securities of the Issuer beneficially owned
by Capital. Capital and Mr. Kolchinsky disclaim beneficial ownership of the securities reported in this Schedule 13G Statement
(the &ldquo;Statement&rdquo;) other than for the purpose of determining their obligations under Section 13(d) of the Act, and
neither the filing of the Statement nor the filing of this Amendment shall be deemed an admission that either Capital or Mr. Kolchinsky
is or was the beneficial owner of such securities for any other purpose.</P>

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

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

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

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

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0in">(e)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>CUSIP Number:
</B>00211Y407</P>

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">(e) RA Capital Management LLC is a registered investment adviser
and is filing this statement in accordance with &sect;240.13d-1(b)(1)(ii)(E);</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">(g) Peter Kolchinsky is a control person and is filing this
statement in accordance with &sect;240.13d-1(b)(1)(ii)(G).</P>

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


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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR>
    <TD STYLE="width: 70%; padding: 0; font-size: 10pt; text-indent: 0"><FONT STYLE="font-size: 10pt">CUSIP No. </FONT><B>00211Y407</B></TD>
    <TD STYLE="width: 30%; padding: 0; font-size: 10pt; text-align: center; text-indent: 0"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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

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

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

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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<tr style="vertical-align: top">
    <TD>(a)</td>
    <td colspan="2"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Amount Beneficially Owned:</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">See the response(s) to Item 9 on the attached cover
page(s).</P></td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <td colspan="2">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD>(b)</td>
    <td colspan="2"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Percent of Class:</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">See the response(s) to Item 11 on the attached cover
        page(s).</P></td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <td colspan="2">&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD>(c)</td>
    <td colspan="2">Number of shares as to which such person has:</td></tr>
<tr style="vertical-align: top">
    <TD STYLE="width: 0.5in"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></td>
    <TD STYLE="width: 0.5in">(i)</td>
    <TD><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">sole power to vote or to direct the vote:</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">See the response(s) to Item 5 on the attached cover
        page(s).</P></td></tr>
<tr style="vertical-align: top">
    <TD><FONT STYLE="font-size: 10pt">&nbsp;</FONT></td>
    <TD>&nbsp;</td>
    <TD>&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD><FONT STYLE="font-size: 10pt">&nbsp;</FONT></td>
    <TD>(ii)</td>
    <TD><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">shared power to vote or to direct the vote</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">See the response(s) to Item 6 on the attached cover
        page(s).</P></td></tr>
<tr style="vertical-align: top">
    <TD><FONT STYLE="font-size: 10pt">&nbsp;</FONT></td>
    <TD>&nbsp;</td>
    <TD>&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD><FONT STYLE="font-size: 10pt">&nbsp;</FONT></td>
    <TD>(iii)</td>
    <TD><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">sole power to dispose or to direct the disposition
        of</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">See the response(s) to Item 7 on the attached cover
        page(s).</P></td></tr>
<tr style="vertical-align: top">
    <TD><FONT STYLE="font-size: 10pt">&nbsp;</FONT></td>
    <TD>&nbsp;</td>
    <TD>&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD><FONT STYLE="font-size: 10pt">&nbsp;</FONT></td>
    <TD>(iv)</td>
    <TD><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">shared power to dispose or to direct the disposition
        of</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">See the response(s) to Item 8 on the attached cover
        page(s).</P></td></tr>
</table>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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

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

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

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

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

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

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

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

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

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

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

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


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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR>
    <TD STYLE="width: 70%; padding: 0; font-size: 10pt; text-indent: 0"><FONT STYLE="font-size: 10pt">CUSIP No. </FONT><B>00211Y407</B></TD>
    <TD STYLE="width: 30%; padding: 0; font-size: 10pt; text-align: center; text-indent: 0"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>&nbsp;</B></P>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="width: 100%; font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0%"></TD><TD STYLE="width: 0.5in">1</TD><TD>Joint Filing Agreement by and among the Reporting Persons is incorporated
                                         herein by reference to Exhibit 1 to the Schedule 13G filed by the Reporting Persons with
                                         the Securities and Exchange Commission on June 25, 2015.</TD></TR></TABLE>

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


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

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

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

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

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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<tr style="vertical-align: top">
    <TD STYLE="width: 50%">&nbsp;</td>
    <TD STYLE="width: 50%; text-decoration: none"><FONT STYLE="text-transform: uppercase">Date: F</FONT>ebruary 14<FONT STYLE="text-transform: uppercase">,
    2017</FONT></td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <TD>&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <TD>RA CAPITAL MANAGEMENT, LLC</td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <TD>&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <TD STYLE="border-bottom: Black 1pt solid">By: /s/ Rajeev Shah</td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <TD>Rajeev Shah</td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <TD>Authorized Signatory</td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <TD>&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <TD>PETER KOLCHINSKY</td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <TD>&nbsp;</td></tr>
<tr style="vertical-align: top">
    <TD>&nbsp;</td>
    <TD STYLE="border-bottom: Black 1pt solid">/s/ Peter Kolchinsky</td></tr>
</table>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>


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