<SEC-DOCUMENT>0001144204-12-015585.txt : 20120316
<SEC-HEADER>0001144204-12-015585.hdr.sgml : 20120316
<ACCEPTANCE-DATETIME>20120316152634
ACCESSION NUMBER:		0001144204-12-015585
CONFORMED SUBMISSION TYPE:	SC 13G
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20120316
DATE AS OF CHANGE:		20120316
GROUP MEMBERS:		PETER KOLCHINSKY
GROUP MEMBERS:		RA CAPITAL HEALTHCARE FUND, L.P.

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			XOMA Corp
		CENTRAL INDEX KEY:			0000791908
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				942756657
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-38028
		FILM NUMBER:		12697522

	BUSINESS ADDRESS:	
		STREET 1:		2910 SEVENTH ST
		CITY:			BERKELEY
		STATE:			CA
		ZIP:			94710
		BUSINESS PHONE:		5106441170

	MAIL ADDRESS:	
		STREET 1:		2910 SEVENTH ST
		CITY:			BERKLEY
		STATE:			CA
		ZIP:			94710

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	XOMA LTD /DE/
		DATE OF NAME CHANGE:	19990107

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	XOMA CORP /DE/
		DATE OF NAME CHANGE:	19920703

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

	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
<SEQUENCE>1
<FILENAME>v306296_sc13-g.htm
<TEXT>
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<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">&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: 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; text-indent: 0in"><B>(Amendment No.__)*</B></P>

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

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

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

<HR NOSHADE SIZE="1" STYLE="color: Black; width: 100%; margin-top: 3pt; margin-bottom: 3pt">
<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">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Common shares, $0.0075 par value</B></P>

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

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<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">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>98419J107</B></P>

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

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<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">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>March 06, 2012</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; text-align: center"></P>

<HR NOSHADE SIZE="1" STYLE="color: Black; width: 100%; margin-top: 3pt; margin-bottom: 3pt">
<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; text-align: center">&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: 6pt"><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">o</FONT></TD><TD STYLE="text-align: justify">Rule 13d-1(b)</TD>
</TR></TABLE>

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<TD STYLE="width: 0.25in"></TD><TD STYLE="width: 0.25in; text-align: left"><FONT STYLE="font-family: Wingdings">x</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: 6pt"><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">o</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">*The remainder of this cover page shall be filled out for a
reporting person&rsquo;s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment
containing information which would alter the disclosures provided in a prior cover page.</P>

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

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

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



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

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

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<TR>
    <TD STYLE="width: 34%; padding: 1.45pt 3pt; font-size: 10pt">CUSIP No. <B>98419J107</B></TD>
    <TD STYLE="width: 32%; padding: 1.45pt 3pt; font-size: 12pt; font-weight: bold; text-align: center">13G</TD>
    <TD STYLE="width: 34%; padding: 1.45pt 3pt; font-size: 10pt; text-align: center">Page <U> <B>2</B> </U> of <U> <B>7</B> </U> Pages</TD></TR>
</TABLE>


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

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

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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt; border-top: Black 1pt solid">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; vertical-align: top; font-size: 10pt; border-top: Black 1pt solid">1.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-top: Black 1pt solid">
        <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">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in"><B>RA Capital Management, LLC&#9;</B></P></TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; vertical-align: top; font-size: 10pt">2.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; font-size: 10pt">Check the Appropriate Box if a Member of a Group (See Instructions)</TD></TR>
<TR>
    <TD STYLE="width: 4%; padding: 1.45pt 3pt 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="width: 7%; padding: 1.45pt 3pt 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="width: 6%; padding: 1.45pt 3pt 6pt; font-size: 10pt">(a)</TD>
    <TD STYLE="width: 83%; padding-bottom: 6pt; font-family: Wingdings">o</TD></TR>
<TR>
    <TD STYLE="padding-bottom: 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding-bottom: 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt 6pt; font-size: 10pt">(b)</TD>
    <TD STYLE="padding-bottom: 6pt; font-family: Wingdings">o</TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">3.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; font-size: 10pt">SEC Use Only</TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">4.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; font-size: 10pt"><FONT STYLE="font-size: 10pt">Citizenship or Place of Organization </FONT> <FONT STYLE="font-size: 10pt"><B>&nbsp;&nbsp;&nbsp;&nbsp;Massachusetts</B></FONT></TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="font-size: 10pt; border-bottom: Black 1pt solid">&nbsp;</TD></TR>
</TABLE>


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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD ROWSPAN="7" STYLE="width: 18%; padding: 1.45pt 3pt; font-size: 10pt">Number of<BR> Shares<BR> Beneficially<BR> Owned by<BR> Each Reporting<BR> Person With</TD>
    <TD STYLE="width: 3%; padding: 1.45pt 3pt; font-size: 10pt">5.</TD>
    <TD STYLE="width: 79%; font-size: 10pt">Sole Voting Power <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5,698,809</B></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">6.</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">Shared Voting Power <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B> <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;0</TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">7.</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">Sole Dispositive Power <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B></B>5,698,809</TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">8.</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">Shared Dispositive Power
    <B>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <B> 0</B></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
</TABLE>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="width: 4%; padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="width: 7%; padding: 1.45pt 3pt; font-size: 10pt">9.</TD>
    <TD STYLE="width: 89%; padding: 1.45pt 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">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <B>5,698,809</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in"></P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">10.</TD>
    <TD STYLE="padding: 1.45pt 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Check if the Aggregate Amount in Row (9) Excludes Certain Shares
        (See Instructions)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>
        <P STYLE="font: 10pt Wingdings; margin: 0pt 0; text-align: right">o</P>
        <P STYLE="font: 10pt Wingdings; margin: 0pt 0; text-align: right">&nbsp;</P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">11.</TD>
    <TD STYLE="padding: 1.45pt 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; text-indent: 0.5in"><B>8.4%</B></P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">12.</TD>
    <TD STYLE="padding: 1.45pt 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; text-indent: 0.5in"><B>IA</B></P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</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">&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"><B>&nbsp;</B>&nbsp;</P>

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

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<TR>
    <TD STYLE="width: 34%; padding: 1.45pt 3pt; font-size: 10pt">CUSIP No. <B>98419J107</B></TD>
    <TD STYLE="width: 32%; padding: 1.45pt 3pt; font-size: 12pt; font-weight: bold; text-align: center">13G</TD>
    <TD STYLE="width: 34%; padding: 1.45pt 3pt; font-size: 10pt; text-align: center">Page <U> <B>3</B> </U> of <U> <B>7</B> </U> Pages</TD></TR>
</TABLE>


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

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

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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt; text-align: justify; border-top: Black 1pt solid">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; vertical-align: top; font-size: 10pt; text-align: justify; border-top: Black 1pt solid">1.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; text-align: justify; border-top: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">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">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in"><B>Peter Kolchinsky&#9;</B></P></TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; vertical-align: top; font-size: 10pt">2.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; font-size: 10pt">Check the Appropriate Box if a Member of a Group (See Instructions)</TD></TR>
<TR>
    <TD STYLE="width: 4%; padding: 1.45pt 3pt 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="width: 7%; padding: 1.45pt 3pt 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="width: 6%; padding: 1.45pt 3pt 6pt; font-size: 10pt">(a)</TD>
    <TD STYLE="width: 83%; padding-bottom: 6pt; font-family: Wingdings">o</TD></TR>
<TR>
    <TD STYLE="padding-bottom: 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding-bottom: 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt 6pt; font-size: 10pt">(b)</TD>
    <TD STYLE="padding-bottom: 6pt; font-family: Wingdings">o</TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">3.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; font-size: 10pt">SEC Use Only</TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">4.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; font-size: 10pt"><FONT STYLE="font-size: 10pt">Citizenship or Place of Organization </FONT> <B>&nbsp;&nbsp;&nbsp;&nbsp;United States</B></TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="font-size: 10pt; border-bottom: Black 1pt solid">&nbsp;</TD></TR>
</TABLE>


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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD ROWSPAN="7" STYLE="width: 18%; padding: 1.45pt 3pt; font-size: 10pt">Number of<BR> Shares<BR> Beneficially<BR> Owned by<BR> Each Reporting<BR> Person With</TD>
    <TD STYLE="width: 3%; padding: 1.45pt 3pt; font-size: 10pt">5.</TD>
    <TD STYLE="width: 79%; font-size: 10pt">Sole Voting Power <B> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5,698,809</B></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">6.</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">Shared Voting Power <B> <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B> <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;0</TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">7.</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">Sole Dispositive Power <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5,698,809</B></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">8.</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">Shared Dispositive Power <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>&nbsp;&nbsp;&nbsp;0</B></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
</TABLE>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="width: 4%; padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="width: 7%; padding: 1.45pt 3pt; font-size: 10pt">9.</TD>
    <TD STYLE="width: 89%; padding: 1.45pt 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; text-indent: 0.5in"><B>5,698,809</P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">10.</TD>
    <TD STYLE="padding: 1.45pt 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Check if the Aggregate Amount in Row (9) Excludes Certain Shares
        (See Instructions)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>
        <P STYLE="font: 10pt Wingdings; margin: 0pt 0; text-align: right">o</P>
        <P STYLE="font: 10pt Wingdings; margin: 0pt 0; text-align: right">&nbsp;</P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">11.</TD>
    <TD STYLE="padding: 1.45pt 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; text-indent: 0.5in"><B>8.4%</B></P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">12.</TD>
    <TD STYLE="padding: 1.45pt 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; text-indent: 0.5in"><B>IN</B></P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</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">&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"><B>&nbsp;</B></P>

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

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

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<TR>
    <TD STYLE="width: 34%; padding: 1.45pt 3pt; font-size: 10pt">CUSIP No. <B>98419J107</B></TD>
    <TD STYLE="width: 32%; padding: 1.45pt 3pt; font-size: 12pt; font-weight: bold; text-align: center">13G</TD>
    <TD STYLE="width: 34%; padding: 1.45pt 3pt; font-size: 10pt; text-align: center">Page <U> <B>4</B> </U> of <U> <B>7</B> </U> Pages</TD></TR>
</TABLE>
<P STYLE="margin: 0">&nbsp;</P>

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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt; border-top: Black 1pt solid">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; vertical-align: top; font-size: 10pt; border-top: Black 1pt solid">1.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-top: Black 1pt solid">
        <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">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in"><B>RA Capital Healthcare Fund, L.P.&#9;</B></P></TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; vertical-align: top; font-size: 10pt">2.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; font-size: 10pt">Check the Appropriate Box if a Member of a Group (See Instructions)</TD></TR>
<TR>
    <TD STYLE="width: 4%; padding: 1.45pt 3pt 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="width: 7%; padding: 1.45pt 3pt 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="width: 6%; padding: 1.45pt 3pt 6pt; font-size: 10pt">(a)</TD>
    <TD STYLE="width: 83%; padding-bottom: 6pt; font-family: Wingdings">o</TD></TR>
<TR>
    <TD STYLE="padding-bottom: 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding-bottom: 6pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt 6pt; font-size: 10pt">(b)</TD>
    <TD STYLE="padding-bottom: 6pt; font-family: Wingdings">o</TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">3.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; font-size: 10pt">SEC Use Only</TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">4.</TD>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; font-size: 10pt"><FONT STYLE="font-size: 10pt">Citizenship or Place of Organization </FONT> <FONT STYLE="font-size: 10pt"><B>&nbsp;&nbsp;&nbsp;&nbsp;Delaware</B></FONT></TD></TR>
<TR>
    <TD COLSPAN="4" STYLE="font-size: 10pt; border-bottom: Black 1pt solid">&nbsp;</TD></TR>
</TABLE>


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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD ROWSPAN="7" STYLE="width: 18%; padding: 1.45pt 3pt; font-size: 10pt">Number of<BR> Shares<BR> Beneficially<BR> Owned by<BR> Each Reporting<BR> Person With</TD>
    <TD STYLE="width: 3%; padding: 1.45pt 3pt; font-size: 10pt">5.</TD>
    <TD STYLE="width: 79%; font-size: 10pt">Sole Voting Power <B> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3,099,013</B></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">6.</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">Shared Voting Power <B> <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B> <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;0</TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">7.</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">Sole Dispositive Power
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B> <B>3,099,013</B></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">8.</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">Shared Dispositive Power <B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>&nbsp;&nbsp;&nbsp;&nbsp;0</B></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
</TABLE>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="width: 4%; padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="width: 7%; padding: 1.45pt 3pt; font-size: 10pt">9.</TD>
    <TD STYLE="width: 89%; padding: 1.45pt 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; text-indent: 0.5in"><B>3,099,013</P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">10.</TD>
    <TD STYLE="padding: 1.45pt 3pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Check if the Aggregate Amount in Row (9) Excludes Certain Shares
        (See Instructions)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>
        <P STYLE="font: 10pt Wingdings; margin: 0pt 0; text-align: right">o</P>
        <P STYLE="font: 10pt Wingdings; margin: 0pt 0; text-align: right">&nbsp;</P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">11.</TD>
    <TD STYLE="padding: 1.45pt 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; text-indent: 0.5in"><B>4.6%</B></P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="padding: 1.45pt 3pt; font-size: 10pt">12.</TD>
    <TD STYLE="padding: 1.45pt 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; text-indent: 0.5in"><B>PN</B></P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</TD></TR>
<TR>
    <TD COLSPAN="3" STYLE="padding: 1.45pt 3pt; font-size: 10pt">&nbsp;</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"></P>

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    <TD STYLE="width: 60%; padding-right: 0; padding-left: 0; tab-stops: center 3.25in right 6.5in; font-size: 10pt">CUSIP No. <B>98419J107</B></TD>
    <TD STYLE="width: 40%; padding-right: 0; padding-left: 0; tab-stops: center 3.25in right 6.5in; font-size: 10pt; text-align: right">Page 5 of 7</TD></TR>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">(a)&#9;<B>Name of Issuer:</B> XOMA Corporation (the &ldquo;Issuer&rdquo;).</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">(b)&#9;<B>Address of the Issuer&rsquo;s Principal Executive
Offices:</B> 2910 Seventh Street, Berkeley, California 94710.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 2.&#9;</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; text-indent: 0in">(a)&#9;<B>Name of Person Filing: </B> This
joint statement on Schedule 13G is being filed by Peter Kolchinsky, RA Capital Management, LLC, and RA Capital Healthcare Fund,
L.P., who are collectively referred to herein as the &ldquo;Reporting Persons.&rdquo; Mr. Kolchinsky (the &ldquo;Manager&rdquo;)
is the manager of RA Capital Management, LLC (&ldquo;Capital&rdquo;), which is the investment adviser and sole general partner
of RA Capital Healthcare Fund, L.P. (&ldquo;Fund&rdquo;) and serves as the investment adviser to a separate discretionary account.
The Reporting Persons have entered into a Joint Filing Agreement, dated as of the date hereof, a copy of which is filed with this
Schedule 13G as <U>Exhibit 1</U> (which is incorporated herein by reference), pursuant to which the Reporting Persons have agreed
to file this statement jointly in accordance with the provisions of Rule 13d-1(k) under the Act.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">(b)&#9;<B>Address of Principal Business Office:
</B>The principal business office of the Reporting Persons with respect to the shares reported hereunder is 20 Park Plaza, Suite
1200, Boston, MA 02116.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">(c) &#9;<B>Citizenship:</B> Capital is a Massachusetts
limited liability company. The Fund is a Delaware limited partnership. The Manager is a United States citizen.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">(d)&#9;<B>Title and Class of Securities: </B>Common
stock (&ldquo;Common Stock&rdquo;).</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in">(e)&#9;<B>CUSIP Number:</B> 98419J107.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 3.&#9;If this statement is filed pursuant to &sect;&sect;240.13d-1(b)
or 240.13d-2(b) or (c), check whether the person filing is a:</B></P>

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 4. &#9;Ownership:</B></P>

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in"><FONT STYLE="font-size: 10pt">In the aggregate,
the Reporting Persons beneficially own 5,698,809 shares of the Common Stock of the Issuer, representing approximately 8.4% of
such class of securities. The Reporting Persons have the right to purchase an additional 687,879 shares of Common Stock pursuant
to the terms of the Warrant to Purchase Common Stock issued on March 09, 2012, which are not exercisable to the extent
that, following such exercise, the total number of shares of Common Stock then beneficially owned by the Reporting Persons does
not exceed 4.999% of the total number of then issued and outstanding shares of Common Stock (including for such purpose the shares
of Common Stock issuable upon such exercise). This 4.999% limitation shall cease to apply from and after the date fourteen days
prior to the Expiration Date. The beneficial ownership of each Reporting Person is as follows: (i) Fund beneficially owns 3,099,013
shares of Common Stock, representing approximately 4.6% of the class and (ii) Capital, as the investment adviser and sole general
partner of the Fund and investment adviser to an account owned by a separate investment vehicle which holds shares of the Issuer's Common Stock, and Mr. Kolchinsky
as the manager of Capital, each beneficially own 5,698,809 shares of Common Stock of the Issuer, representing approximately 8.4%
of the class. The percentage of Common Stock beneficially owned by each Reporting Person is based on a total of 68,043,103 shares
of the Common Stock outstanding as reported on the Issuer&rsquo;s 10-K filed on March 14, 2012.</FONT></P>

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



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

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

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

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<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; border-collapse: collapse; font-family: Times New Roman, Times, Serif">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 60%; padding-right: 0; padding-left: 0; tab-stops: center 3.25in right 6.5in; font-size: 10pt">CUSIP No. <B>98419J107</B></TD>
    <TD STYLE="width: 40%; padding-right: 0; padding-left: 0; tab-stops: center 3.25in right 6.5in; font-size: 10pt; text-align: right">Page 6 of 7</TD></TR>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0in"><FONT STYLE="font-size: 10pt">The Fund has
the power to vote and dispose of the shares of Common Stock beneficially owned by such entity (as described above). Capital, as
the investment adviser and sole general partner of the Fund and as the investment adviser&nbsp;to&nbsp;an account owned by a separate
investment vehicle which holds shares of the Issuer&rsquo;s Common Stock, has the
sole authority to vote and dispose of all of the shares of Common Stock reported in this Schedule 13G. The Manager, by virtue
of his position as manager of Capital, has the sole authority to vote and dispose of all of the shares of Common Stock reported
in this Schedule 13G.</FONT></P>

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 5.&#9;&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">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 1in; text-indent: -1in"><B>Item 6.&#9;&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 0pt 1in; text-indent: -1in">&nbsp;</P>

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 7. &#9;&nbsp;&nbsp;Identification and Classification of the Subsidiary
Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person:</B></P>

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 8.&#9;&nbsp;&nbsp;&nbsp;Identification and Classification of Members of
the Group:</B></P>

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

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

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

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

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 10.&#9;Certification:</B></P>

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

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

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

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<TR STYLE="vertical-align: top">
    <TD STYLE="width: 60%; padding-right: 0; padding-left: 0; tab-stops: center 3.25in right 6.5in; font-size: 10pt">CUSIP No. <B>98419J107</B></TD>
    <TD STYLE="width: 40%; padding-right: 0; padding-left: 0; tab-stops: center 3.25in right 6.5in; font-size: 10pt; text-align: right">Page 7 of 7</TD></TR>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><I>Signature</I></P>

<P STYLE="font: 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-indent: 0.5in">After reasonable inquiry and to the best
of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.</P>

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

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

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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD COLSPAN="2">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="text-transform: uppercase">Date: March 16, 2012</FONT></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD COLSPAN="2">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">RA CAPITAL HEALTHCARE FUND, L.P.</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P></TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="width: 50%; vertical-align: top">&nbsp;</TD>
    <TD STYLE="width: 4%; font-size: 10pt; text-align: left; vertical-align: top">By:&nbsp;</TD>
    <TD STYLE="width: 46%; vertical-align: top">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">RA Capital Management, LLC</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;&nbsp;&nbsp;General Partner</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="width: 50%; vertical-align: top">&nbsp;</TD>
    <TD STYLE="width: 4%; font-size: 10pt">By:&nbsp;</TD>
    <TD STYLE="width: 46%; vertical-align: top; font-size: 10pt">/s/ Peter Kolchinsky</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; border-top: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Peter Kolchinsky</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Manager</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt">RA CAPITAL MANAGEMENT, LLC</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="width: 50%; vertical-align: top">&nbsp;</TD>
    <TD STYLE="width: 4%; font-size: 10pt">By:&nbsp;</TD>
    <TD STYLE="width: 46%; vertical-align: top; font-size: 10pt">/s/ Peter Kolchinsky</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; border-top: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Peter Kolchinsky</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Manager</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt">PETER KOLCHINSKY</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt; border-bottom: Black 1pt solid">/s/ Peter Kolchinsky</TD></TR>
<TR>
    <TD STYLE="vertical-align: top; width: 50%">&nbsp;</TD>
    <TD STYLE="width: 4%">&nbsp;</TD>
    <TD STYLE="vertical-align: top; width: 46%">&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in"></P>

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><U>Exhibit 1</U></P>

<P STYLE="font: 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"><U>JOINT FILING AGREEMENT</U></P>

<P STYLE="font: 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-indent: 0.5in">Pursuant to Rule 13d-1(k)(1) under the Securities
Exchange Act of 1934, as amended, the undersigned hereby agrees, as of March 16, 2012, that only one statement containing the information
required by Schedule 13G, and each amendment thereto, need be filed with respect to the ownership by each of the undersigned of
shares of Common Stock of XOMA Corporation, and such statement to which this Joint Filing Agreement is attached as <U>Exhibit 1</U>
is filed on behalf of each of the undersigned.</P>

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

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




<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD COLSPAN="2">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">RA CAPITAL HEALTHCARE FUND, L.P.</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P></TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="width: 50%; vertical-align: top">&nbsp;</TD>
    <TD STYLE="width: 4%; font-size: 10pt; text-align: left; vertical-align: top">By:&nbsp;</TD>
    <TD STYLE="width: 46%; vertical-align: top">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">RA Capital Management, LLC</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;&nbsp;&nbsp;General Partner</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="width: 50%; vertical-align: top">&nbsp;</TD>
    <TD STYLE="width: 4%; font-size: 10pt">By:&nbsp;</TD>
    <TD STYLE="width: 46%; vertical-align: top; font-size: 10pt">/s/ Peter Kolchinsky</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; border-top: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Peter Kolchinsky</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Manager</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt">RA CAPITAL MANAGEMENT, LLC</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="width: 50%; vertical-align: top">&nbsp;</TD>
    <TD STYLE="width: 4%; font-size: 10pt">By:&nbsp;</TD>
    <TD STYLE="width: 46%; vertical-align: top; font-size: 10pt">/s/ Peter Kolchinsky</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; border-top: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Peter Kolchinsky</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Manager</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font-family: Times New Roman, Times, Serif">
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt">PETER KOLCHINSKY</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt; border-bottom: Black 1pt solid">/s/ Peter Kolchinsky</TD></TR>
<TR>
    <TD STYLE="vertical-align: top; width: 50%">&nbsp;</TD>
    <TD STYLE="width: 4%">&nbsp;</TD>
    <TD STYLE="vertical-align: top; width: 46%">&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in"></P>

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

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