<SEC-DOCUMENT>0000947871-24-000805.txt : 20241017
<SEC-HEADER>0000947871-24-000805.hdr.sgml : 20241017
<ACCEPTANCE-DATETIME>20241017161624
ACCESSION NUMBER:		0000947871-24-000805
CONFORMED SUBMISSION TYPE:	SC 13D
PUBLIC DOCUMENT COUNT:		2
FILED AS OF DATE:		20241017
DATE AS OF CHANGE:		20241017
GROUP MEMBERS:		ORBIMED ADVISORS ISRAEL II LTD
GROUP MEMBERS:		ORBIMED CAPITAL GP VIII LLC
GROUP MEMBERS:		ORBIMED ISRAEL GP II, L.P.

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Upstream Bio, Inc.
		CENTRAL INDEX KEY:			0002022626
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13D
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-94651
		FILM NUMBER:		241377773

	BUSINESS ADDRESS:	
		STREET 1:		890 WINTER STREET, SUITE 200
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451
		BUSINESS PHONE:		781-208-2466

	MAIL ADDRESS:	
		STREET 1:		890 WINTER STREET, SUITE 200
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ORBIMED ADVISORS LLC
		CENTRAL INDEX KEY:			0001055951
		ORGANIZATION NAME:           	
		IRS NUMBER:				133976876
		STATE OF INCORPORATION:			DE

	FILING VALUES:
		FORM TYPE:		SC 13D

	BUSINESS ADDRESS:	
		STREET 1:		601 LEXINGTON AVENUE
		STREET 2:		54TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		(212) 739-6400

	MAIL ADDRESS:	
		STREET 1:		601 LEXINGTON AVENUE
		STREET 2:		54TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13D
<SEQUENCE>1
<FILENAME>ss4005698_sc13d.htm
<DESCRIPTION>SCHEDULE 13D
<TEXT>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center"></P>

<!-- Field: Rule-Page --><DIV STYLE="margin-top: 12pt; margin-bottom: 3pt; width: 100%"><DIV STYLE="font-size: 1pt; border-top: Black 2pt solid; border-bottom: Black 1pt solid">&nbsp;</DIV></DIV><!-- Field: /Rule-Page -->

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center"><B>Washington, D.C. 20549</B></P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 16pt Times New Roman, Times, Serif; margin: 0 9.35pt 0 0; text-align: center"><B>SCHEDULE 13D</B></P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 9.35pt 0 0; text-align: center"><B>Under the Securities Exchange Act of
1934</B></P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

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    <TD STYLE="width: 100%; padding: 2.25pt; font: 12pt Times New Roman, Times, Serif; text-align: center"><FONT STYLE="font-size: 16pt"><B>Upstream Bio, Inc.</B></FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-top: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">(Name of Issuer)</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center; text-indent: 1in">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>Common Stock</B></FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">(Title of Class of Securities)</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center; text-indent: 0.75in">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>91678A107</B></FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">(CUSIP Number)</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center"><B>OrbiMed Advisors LLC</B></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center"><B>OrbiMed Capital GP VIII LLC</B></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center"><B>OrbiMed Israel GP II, L.P.</B></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center"><B>OrbiMed Advisors Israel II Limited</B></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center"><B>&nbsp;</B></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center"><B>601 Lexington Avenue, 54th Floor</B></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center"><B>New York, NY 10022</B></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center"><B>Telephone: (212) 739-6400</B></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">(Name, Address and Telephone Number of Person Authorized
    to<BR>
    Receive Notices and Communications)</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center; text-indent: 1in">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>October 15, 2024</B></FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 10pt">(Date of Event which Requires Filing of this Statement)</FONT></TD></TR>
  </TABLE>
<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">If the filing person has previously filed a statement on Schedule 13G to
report the acquisition that is the subject of this Schedule&nbsp;13D, and is filing this schedule because of &sect;&sect;240.13d-1(e),
240.13d-1(f) or 240.13d-1(g), check the following box.&nbsp; &#9744;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0"><B>Note:</B>&nbsp; Schedules filed in paper format shall include a signed
original and five copies of the schedule, including all exhibits.&nbsp; See &sect;240.13d-7(b) for other parties to whom copies are to
be sent.</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

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    <TD STYLE="width: 18px; font: 12pt Times New Roman, Times, Serif"><FONT STYLE="font-size: 10pt">*</FONT></TD>
    <TD STYLE="font: 12pt Times New Roman, Times, Serif"><FONT STYLE="font-size: 10pt">The remainder of this cover page shall be filled out for a Reporting Person&#8217;s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.</FONT></TD></TR>
  </TABLE>
<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">The information required on the remainder of this cover page shall not
be deemed to be &#8220;filed&#8221; for the purpose of Section 18 of the Securities Exchange Act of 1934 (&#8220;<U>Act</U>&#8221;) 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: 0"></P>

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



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    <DIV STYLE="margin-top: 6pt; margin-bottom: 6pt"><TABLE CELLPADDING="0" CELLSPACING="0" STYLE="border-collapse: collapse; width: 100%; font-size: 10pt"><TR STYLE="vertical-align: top; text-align: left"><TD STYLE="width: 33%">&nbsp;</TD><TD STYLE="width: 34%; text-align: center">&nbsp;</TD><TD STYLE="width: 33%">&nbsp;</TD></TR></TABLE></DIV>
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<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>

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    <TD STYLE="width: 30%; border: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 6pt"><FONT STYLE="font-size: 10pt"><B>CUSIP No.&nbsp;</B> 91678A107</FONT></TD>
    <TD STYLE="width: 40%; padding: 6pt 6pt 1.5pt; font: 12pt Times New Roman, Times, Serif; text-align: center">&nbsp;</TD>
    <TD STYLE="width: 30%; padding: 6pt; font: 12pt Times New Roman, Times, Serif">&nbsp;</TD></TR>
  </TABLE>
<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; border-collapse: collapse">
  <TR>
    <TD STYLE="border-top: Black 1pt solid; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">1</FONT></TD>
    <TD COLSPAN="4" STYLE="border-top: Black 1pt solid; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Names of Reporting Persons.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">OrbiMed Advisors LLC</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">2</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Check the Appropriate Box if a Member of a Group (See Instructions).</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">(a) <FONT STYLE="font-family: Wingdings">o</FONT></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">(b) <FONT STYLE="font-family: Wingdings">o</FONT></P></TD>
    <TD STYLE="white-space: nowrap; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">3</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">SEC Use Only&nbsp;&nbsp;</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">4</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Source of Funds (See Instructions)</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">AF</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">5</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">Check if Disclosure of Legal Proceedings Is Required Pursuant to Items&nbsp;2(d) or 2(e)</FONT></TD>
    <TD STYLE="vertical-align: top; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-family: Wingdings; font-size: 10pt">o</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">6</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Citizenship or Place of Organization&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Delaware</P></TD></TR>
  <TR>
    <TD COLSPAN="2" ROWSPAN="4" STYLE="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">NUMBER OF</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">SHARES</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">BENEFICIALLY</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">OWNED BY</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">EACH</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">REPORTING</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">PERSON</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">WITH</P></TD>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">7</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Sole Voting Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">0</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">8</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Shared Voting Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">4,554,873</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">9</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Sole Dispositive Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">0</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">10</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Shared Dispositive Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">4,554,873</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">11</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Aggregate Amount Beneficially Owned by Each Reporting Person&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">4,554,873</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">12</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)</FONT></TD>
    <TD STYLE="vertical-align: top; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-family: Wingdings; font-size: 10pt">o</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">13</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Percent of Class Represented by Amount in Row (11)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">8.9%*</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">14</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Type of Reporting Person (See Instructions)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">IA</P></TD></TR>
  <TR>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 12%">&nbsp;</TD>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 71%">&nbsp;</TD>
    <TD STYLE="width: 5%">&nbsp;</TD></TR>
  </TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify">* This percentage is calculated based upon 51,341,695
shares of common stock, par value $0.001 per share, outstanding of Upstream Bio, Inc. (the &#8220;<U>Issuer</U>&#8221;) following the
closing of the Issuer&#8217;s initial public offering, as set forth in the Issuer&#8217;s Rule 424(b)(4) Prospectus filed with the Securities
and Exchange Commission on October 11, 2024, without giving effect to an additional 2,250,000 shares that may be issued and sold by the
Issuer to the underwriters pursuant to the underwriters&#8217; option.</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0"></P>

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    <DIV STYLE="break-before: page; margin-top: 6pt; margin-bottom: 6pt"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
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<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: top">
    <TD STYLE="width: 30%; border: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 6pt"><FONT STYLE="font-size: 10pt"><B>CUSIP No.&nbsp;</B> 91678A107</FONT></TD>
    <TD STYLE="width: 40%; padding: 6pt 6pt 1.5pt; font: 12pt Times New Roman, Times, Serif; text-align: center">&nbsp;</TD>
    <TD STYLE="width: 30%; padding: 6pt; font: 12pt Times New Roman, Times, Serif">&nbsp;</TD></TR>
  </TABLE>
<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; border-collapse: collapse">
  <TR>
    <TD STYLE="border-top: Black 1pt solid; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">1</FONT></TD>
    <TD COLSPAN="4" STYLE="border-top: Black 1pt solid; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Names of Reporting Persons.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">OrbiMed Capital GP VIII LLC</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">2</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Check the Appropriate Box if a Member of a Group (See Instructions).</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">(a) <FONT STYLE="font-family: Wingdings">o</FONT></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">(b) <FONT STYLE="font-family: Wingdings">o</FONT></P></TD>
    <TD STYLE="white-space: nowrap; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">3</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">SEC Use Only&nbsp;&nbsp;</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">4</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Source of Funds (See Instructions)</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">AF</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">5</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">Check if Disclosure of Legal Proceedings Is Required Pursuant to Items&nbsp;2(d) or 2(e)</FONT></TD>
    <TD STYLE="vertical-align: top; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-family: Wingdings; font-size: 10pt">o</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">6</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Citizenship or Place of Organization&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Delaware</P></TD></TR>
  <TR>
    <TD COLSPAN="2" ROWSPAN="4" STYLE="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">NUMBER OF</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">SHARES</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">BENEFICIALLY</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">OWNED BY</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">EACH</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">REPORTING</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">PERSON</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">WITH</P></TD>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">7</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Sole Voting Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">0</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">8</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Shared Voting Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">4,554,873</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">9</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Sole Dispositive Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">0</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">10</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Shared Dispositive Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">4,554,873</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">11</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Aggregate Amount Beneficially Owned by Each Reporting Person&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">4,554,873</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">12</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)</FONT></TD>
    <TD STYLE="vertical-align: top; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-family: Wingdings; font-size: 10pt">o</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">13</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Percent of Class Represented by Amount in Row (11)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">8.9%*</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">14</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Type of Reporting Person (See Instructions)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">OO</P></TD></TR>
  <TR>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 12%">&nbsp;</TD>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 71%">&nbsp;</TD>
    <TD STYLE="width: 5%">&nbsp;</TD></TR>
  </TABLE>
<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify">* This percentage is calculated based upon 51,341,695
shares of common stock, par value $0.001 per share, outstanding of Upstream Bio, Inc. (the &#8220;<U>Issuer</U>&#8221;) following the
closing of the Issuer&#8217;s initial public offering, as set forth in the Issuer&#8217;s Rule 424(b)(4) Prospectus filed with the Securities
and Exchange Commission on October 11, 2024, without giving effect to an additional 2,250,000 shares that may be issued and sold by the
Issuer to the underwriters pursuant to the underwriters&#8217; option.</P>

<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"></P>

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    <DIV STYLE="break-before: page; margin-top: 6pt; margin-bottom: 6pt"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
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<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: top">
    <TD STYLE="width: 30%; border: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 6pt"><FONT STYLE="font-size: 10pt"><B>CUSIP No.&nbsp;</B> 91678A107</FONT></TD>
    <TD STYLE="width: 40%; padding: 6pt 6pt 1.5pt; font: 12pt Times New Roman, Times, Serif; text-align: center">&nbsp;</TD>
    <TD STYLE="width: 30%; padding: 6pt; font: 12pt Times New Roman, Times, Serif">&nbsp;</TD></TR>
  </TABLE>
<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; border-collapse: collapse">
  <TR>
    <TD STYLE="border-top: Black 1pt solid; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">1</FONT></TD>
    <TD COLSPAN="4" STYLE="border-top: Black 1pt solid; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Names of Reporting Persons.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">OrbiMed Advisors Israel II Limited</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">2</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Check the Appropriate Box if a Member of a Group (See Instructions).</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">(a) <FONT STYLE="font-family: Wingdings">o</FONT></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">(b) <FONT STYLE="font-family: Wingdings">o</FONT></P></TD>
    <TD STYLE="white-space: nowrap; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">3</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">SEC Use Only&nbsp;&nbsp;</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">4</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Source of Funds (See Instructions)</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">AF</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">5</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">Check if Disclosure of Legal Proceedings Is Required Pursuant to Items&nbsp;2(d) or 2(e)</FONT></TD>
    <TD STYLE="vertical-align: top; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-family: Wingdings; font-size: 10pt">o</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">6</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Citizenship or Place of Organization&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Cayman Islands</P></TD></TR>
  <TR>
    <TD COLSPAN="2" ROWSPAN="4" STYLE="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">NUMBER OF</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">SHARES</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">BENEFICIALLY</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">OWNED BY</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">EACH</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">REPORTING</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">PERSON</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">WITH</P></TD>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">7</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Sole Voting Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">0</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">8</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Shared Voting Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">1,138,716</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">9</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Sole Dispositive Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">0</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">10</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Shared Dispositive Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">1,138,716</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">11</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Aggregate Amount Beneficially Owned by Each Reporting Person&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">1,138,716</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">12</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)</FONT></TD>
    <TD STYLE="vertical-align: top; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-family: Wingdings; font-size: 10pt">o</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">13</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Percent of Class Represented by Amount in Row (11)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">2.2%*</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">14</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Type of Reporting Person (See Instructions)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">CO</P></TD></TR>
  <TR>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 12%">&nbsp;</TD>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 71%">&nbsp;</TD>
    <TD STYLE="width: 5%">&nbsp;</TD></TR>
  </TABLE>
<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0">* This percentage is calculated based upon 51,341,695 shares of common stock,
par value $0.001 per share, outstanding of Upstream Bio, Inc. (the &#8220;<U>Issuer</U>&#8221;) following the closing of the Issuer&#8217;s
initial public offering, as set forth in the Issuer&#8217;s Rule 424(b)(4) Prospectus filed with the Securities and Exchange Commission
on October 11, 2024, without giving effect to an additional 2,250,000 shares that may be issued and sold by the Issuer to the underwriters
pursuant to the underwriters&#8217; option.</P>

<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0"></P>

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    <DIV STYLE="break-before: page; margin-top: 6pt; margin-bottom: 6pt"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
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<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: top">
    <TD STYLE="width: 30%; border: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 6pt"><FONT STYLE="font-size: 10pt"><B>CUSIP No.&nbsp;</B> 91678A107</FONT></TD>
    <TD STYLE="width: 40%; padding: 6pt 6pt 1.5pt; font: 12pt Times New Roman, Times, Serif; text-align: center">&nbsp;</TD>
    <TD STYLE="width: 30%; padding: 6pt; font: 12pt Times New Roman, Times, Serif">&nbsp;</TD></TR>
  </TABLE>
<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; border-collapse: collapse">
  <TR>
    <TD STYLE="border-top: Black 1pt solid; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">1</FONT></TD>
    <TD COLSPAN="4" STYLE="border-top: Black 1pt solid; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Names of Reporting Persons.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">OrbiMed Israel GP II, L.P.</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">2</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Check the Appropriate Box if a Member of a Group (See Instructions).</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">(a) <FONT STYLE="font-family: Wingdings">o</FONT></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">(b) <FONT STYLE="font-family: Wingdings">o</FONT></P></TD>
    <TD STYLE="white-space: nowrap; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">3</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">SEC Use Only&nbsp;&nbsp;</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">4</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Source of Funds (See Instructions)</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">AF</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">5</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">Check if Disclosure of Legal Proceedings Is Required Pursuant to Items&nbsp;2(d) or 2(e)</FONT></TD>
    <TD STYLE="vertical-align: top; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-family: Wingdings; font-size: 10pt">o</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">6</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Citizenship or Place of Organization&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Cayman Islands</P></TD></TR>
  <TR>
    <TD COLSPAN="2" ROWSPAN="4" STYLE="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">NUMBER OF</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">SHARES</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">BENEFICIALLY</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">OWNED BY</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">EACH</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">REPORTING</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">PERSON</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: center">WITH</P></TD>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">7</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Sole Voting Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">0</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">8</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Shared Voting Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">1,138,716</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">9</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Sole Dispositive Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">0</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">10</FONT></TD>
    <TD COLSPAN="2" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Shared Dispositive Power&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">1,138,716</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">11</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Aggregate Amount Beneficially Owned by Each Reporting Person&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">1,138,716</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">12</FONT></TD>
    <TD COLSPAN="3" STYLE="border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt"><FONT STYLE="font-size: 10pt">Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)</FONT></TD>
    <TD STYLE="vertical-align: top; border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-family: Wingdings; font-size: 10pt">o</FONT></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">13</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Percent of Class Represented by Amount in Row (11)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">2.2%*</P></TD></TR>
  <TR>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 2.25pt; text-align: center"><FONT STYLE="font-size: 14pt">14</FONT></TD>
    <TD COLSPAN="4" STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; padding: 2.25pt">
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">Type of Reporting Person (See Instructions)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">PN</P></TD></TR>
  <TR>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 12%">&nbsp;</TD>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 71%">&nbsp;</TD>
    <TD STYLE="width: 5%">&nbsp;</TD></TR>
  </TABLE>
<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0">* This percentage is calculated based upon 51,341,695 shares of common stock,
par value $0.001 per share, outstanding of Upstream Bio, Inc. (the &#8220;<U>Issuer</U>&#8221;) following the closing of the Issuer&#8217;s
initial public offering, as set forth in the Issuer&#8217;s Rule 424(b)(4) Prospectus filed with the Securities and Exchange Commission
on October 11, 2024, without giving effect to an additional 2,250,000 shares that may be issued and sold by the Issuer to the underwriters
pursuant to the underwriters&#8217; option.</P>

<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0"></P>

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    <DIV STYLE="break-before: page; margin-top: 6pt; margin-bottom: 6pt"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
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<P STYLE="font: 8pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">This Statement on Schedule 13D
(this &#8220;<U>Statement</U>&#8221;) relates to the common stock, par value $0.001 per share (the &#8220;<U>Shares</U>&#8221;), of Upstream
Bio, Inc., <FONT STYLE="background-color: white">a corporation organized under the laws of Delaware</FONT> (the &#8220;<U>Issuer</U>&#8221;),
with its principal executive offices located at <FONT STYLE="background-color: white">890 Winter Street, Suite 200, Waltham, MA 02451</FONT>.
The Shares are listed on the NASDAQ Global Select Market under the ticker symbol &#8220;UPB&#8221;. Information given in response to each
item shall be deemed incorporated by reference in all other items, as applicable.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">On October 15, 2024, the Issuer
completed its initial public offering pursuant to which the Issuer agreed to issue and sell 15,000,000 Shares to the participants in the
offering (the &#8220;<U>IPO</U>&#8221;). In addition, the Issuer granted the underwriters of the IPO an option to purchase, at the public
offering price less any underwriting discounts and commissions, up to an additional 2,250,000 Shares. The purchase price for each Share
was $17.00. As a result of the IPO, the Issuer&#8217;s total number of outstanding Shares increased to 51,341,695 (without giving effect
to the additional 2,250,000 shares that may be issued and sold by the Issuer to the underwriters pursuant to the underwriters&#8217; option).</P>

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">(a) This Statement is being filed
by OrbiMed Advisors LLC (&#8220;<U>OrbiMed Advisors</U>&#8221;), OrbiMed Capital GP VIII LLC, (&#8220;<U>GP VIII</U>&#8221;), OrbiMed
Advisors Israel II Limited (&#8220;<U>Advisors II</U>&#8221;), and OrbiMed Israel GP II, L.P. (&#8220;<U>Israel GP</U>&#8221;) (collectively,
the &#8220;<U>Reporting Persons</U>&#8221;).</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">(b) &#8212; (c), (f) OrbiMed Advisors,
a limited liability company organized under the laws of Delaware and a registered investment adviser under the Investment Advisers Act
of 1940, as amended, is the managing member or general partner of certain entities as more particularly described in Item 6 below.&nbsp;OrbiMed
Advisors has its principal offices at 601 Lexington Avenue, 54th Floor, New York, New York 10022.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">GP VIII, a limited liability company
organized under the laws of Delaware, is the general partner of a limited partnership, as more particularly described in Item 6 below.&nbsp;GP
VIII has its principal offices at 601 Lexington Avenue, 54th Floor, New York, New York 10022.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Advisors II, an exempted company
organized under the laws of the Cayman Islands, is the general partner of Israel GP. Advisors II has its principal offices at 5 Hahoshlim
Street, Building B, 1st Floor, Herzliya Pituach, Israel.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Israel GP, an exempted limited
partnership organized under the laws of the Cayman Islands, is the general partner of a limited partnership, as more particularly described
in Item 6 below, Israel GP has its principal offices at 5 Hahoshlim Street, Building B, 1st Floor, Herzliya Pituach, Israel.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The directors and executive officers
of OrbiMed Advisors, GP VIII, Advisors II, and Israel GP are set forth on Schedules I, II, III, and IV, respectively, attached hereto.&nbsp;Schedules
I through IV set forth the following information with respect to each such person:</P>

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

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

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">(iii)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;present
principal occupation of employment and the name, principal business and address of any corporation or other organization in which such
employment is conducted; and</P>

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">(d) &#8212; (e) During the last
five years, neither the Reporting Persons nor any Person named in Schedules I or II has been (i) convicted in a criminal proceeding (excluding
traffic violations or similar misdemeanors) or (ii) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction
and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting
or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.</P>

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0"><B>Item 3.&nbsp; Source and Amount of Funds or Other Consideration</B></P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in">&#9;In October 2021, Advisors
II and Israel GP, pursuant to their authority under the limited partnership agreement of OrbiMed Israel Partners II, L.P. (&#8220;<U>OIP
II</U>&#8221;), as more particularly described in Item 6 below, caused OIP II to purchase 275,000 shares of the Issuer&#8217;s Series
A redeemable convertible preferred stock (&#8220;<U>Series A Shares</U>&#8221;) and OrbiMed Advisors and GP VIII, pursuant to their authority
under the limited partnership agreement of OrbiMed Private Investments VIII, L.P. (&#8220;<U>OPI VIII</U>&#8221;), as more particularly
described in Item 6 below, caused OPI VIII to purchase 1,100,000 Series A Shares, each at a price of $10.00 per Series A Share.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in">&#9;In October 2022, Advisors
II and Israel GP, pursuant to their authority under the limited partnership agreement of OIP II, and OrbiMed Advisors and GP VIII, pursuant
to their authority under the limited partnership agreement of OPI VIII, caused OIP II and OPI VIII to purchase 225,000 and 900,000 Series
A Shares, respectively, at a price of $10.00 per Series A Share.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in">&#9;In June 2023, Advisors II
and Israel GP, pursuant to their authority under the limited partnership agreement of OIP II, and OrbiMed Advisors and GP VIII, pursuant
to their authority under the limited partnership agreement of OPI VIII, caused OIP II and OPI VIII to purchase 47,058 and 188,235 shares
of the Issuer&#8217;s Series B redeemable convertible preferred stock (&#8220;<U>Series B Shares</U>&#8221;), respectively, at a price
of $17.00 per Series B Share.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in">&#9;In April 2024, Advisors II
and Israel GP, pursuant to their authority under the limited partnership agreement of OIP II, and OrbiMed Advisors and GP VIII, pursuant
to their authority under the limited partnership agreement of OPI VIII, caused OIP II and OPI VIII to purchase 141,176 and 564,705 Series
B Shares, respectively, at a price of $17.00 per Series B Share.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in">&#9;Each Series A Share and Series
B Share automatically converted into Shares on a one-for-1.049 basis immediately prior to the closing of the IPO.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">On and prior to the closing of
the IPO, OrbiMed Advisors and GP VIII, pursuant to their authority under the limited partnership agreement of OPI VIII, caused OPI VIII
to purchase 660,000 Shares in the IPO, and Advisors II and Israel GP, pursuant to their authority under the limited partnership agreement
of OIP II, caused OIP II to purchase 165,000 Shares in the IPO.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The source of funds for such purchases
was the working capital of OPI VIII and OIP II, respectively.</P>

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

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

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">This Statement relates to the
acquisition of Shares by the Reporting Persons. The Shares acquired by the Reporting Persons were acquired for the purpose of making an
investment in the Issuer and not with the intention of acquiring control of the Issuer&#8217;s business on behalf of the Reporting Persons&#8217;
respective advisory clients.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The Reporting Persons from time
to time intend to review their investment in the Issuer on the basis of various factors, including the Issuer&#8217;s business, financial
condition, results of operations and prospects, general economic and industry conditions, the securities markets in general and those
for the Issuer&#8217;s Shares in particular, as well as other developments and other investment opportunities. Based upon such review,
the Reporting Persons will take such actions in the future as the Reporting Persons may deem appropriate in light of the circumstances
existing from time to time. If the Reporting Persons believe that further investment in the Issuer is attractive, whether because of the
market price of Shares or otherwise, they may acquire Shares or other securities of the Issuer either in the open market or in privately
negotiated transactions.&nbsp;Similarly, depending on market and other factors, the Reporting Persons may determine to dispose of some
or all of the Shares currently owned by the Reporting Persons or otherwise acquired by the Reporting Persons either in the open market
or in privately negotiated transactions.</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0"></P>

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<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Except as set forth in this Schedule
13D, the Reporting Persons have not formulated any plans or proposals which relate to or would result in:&nbsp; (a) the acquisition by
any person of additional securities of the Issuer or the disposition of securities of the Issuer, (b) an extraordinary corporate transaction,
such as a merger, reorganization or liquidation, involving the Issuer or any of its subsidiaries, (c) a sale or transfer of a material
amount of the assets of the Issuer or any of its subsidiaries, (d) any change in the present Board of Directors or management of the Issuer,
including any plans or proposals to change the number or term of directors or to fill any existing vacancies on the board, (e) any material
change in the Issuer&#8217;s capitalization or dividend policy of the Issuer, (f) any other material change in the Issuer&#8217;s business
or corporate structure, (g) any change in the Issuer&#8217;s charter or bylaws or other instrument corresponding thereto or other action
which may impede the acquisition of control of the Issuer by any person, (h) causing a class of the Issuer&#8217;s securities to be deregistered
or delisted from a national securities exchange or to cease to be authorized to be quoted in an inter-dealer quotation system of a registered
national securities association, (i) a class of equity securities of the Issuer becoming eligible for termination of registration pursuant
to Section 12(g)(4) of the Act or (j) any action similar to any of those enumerated above.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0"><B>Item 5.&nbsp; Interest in Securities of the Issuer</B></P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">&nbsp;(a) &#8212; (b) The following
is based upon 51,341,695 Shares outstanding following the closing of the IPO, as set forth in the Issuer&#8217;s Rule 424(b)(4) Prospectus
filed with the Securities and Exchange Commission on October 11, 2024, without giving effect to an additional 2,250,000 Shares that may
be issued and sold by the Issuer to the underwriters pursuant to the underwriters&#8217; option.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">As of the date of this filing,
OPI VIII, a limited partnership organized under the laws of Delaware, holds 4,554,873 Shares, constituting approximately 8.9% of the issued
and outstanding Shares.&nbsp;GP VIII is the general partner of OPI VIII, pursuant to the terms of the limited partnership agreement of
OPI VIII, and OrbiMed Advisors is the managing member of GP VIII, pursuant to the terms of the limited liability company agreement of
GP VIII. As a result, OrbiMed Advisors and GP VIII share power to direct the vote and disposition of the Shares held by OPI VIII and may
be deemed directly or indirectly, including by reason of their mutual affiliation, to be the beneficial owners of the Shares held by OPI
VIII.&nbsp;OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven
H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the Shares held by OPI VIII.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In addition, OrbiMed Advisors
and GP VIII, pursuant to their authority under the limited partnership agreement of OPI VIII, caused OPI VIII to enter into the agreements
referred to in Item 6 below.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">As of the date of this filing,
OIP II, an exempted limited partnership organized under the laws of the Cayman Islands, holds 1,138,716 Shares, constituting approximately
2.2% of the issued and outstanding Shares. Israel GP is the general partner of OIP II, pursuant to the terms of the limited partnership
agreement of OIP II, and Advisors II is the general partner of Israel GP, pursuant to the terms of the limited partnership agreement of
Israel GP. As a result, Advisors II and Israel GP share power to direct the vote and disposition of the Shares held by OIP II and may
be deemed, directly or indirectly, including by reason of their mutual affiliation, to be the beneficial owners of the Shares held by
OIP II. Advisors II exercises this investment and voting power through an investment committee comprised of Carl L. Gordon, David Bonita,
and Erez Chimovits, each of whom disclaims beneficial ownership of the Shares held by OIP II.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In addition, Advisors II and Israel
GP, pursuant to their authority under the limited partnership agreement of OIP II, caused OIP II to enter into the agreements referred
to in Item 6 below.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">(c) Except as disclosed in Item
3, the Reporting Persons have not effected any transactions during the past sixty (60) days in any Shares.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">(d) Not applicable.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">(e) Not applicable.</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0"><B>Item 6.&nbsp; Contracts, Arrangements, Understandings or Relationships
with Respect to Securities of the Issuer</B></P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In addition to the relationships
between the Reporting Persons described in Items 2 and 5 above, GP VIII is the general partner of OPI VIII, pursuant to the terms of the
limited partnership agreement of OPI VIII.&nbsp;Pursuant to this agreement and relationship, GP VIII has discretionary investment management
authority with respect to the assets of OPI VIII. Such authority includes the power to vote and otherwise dispose of securities held by
OPI VIII.&nbsp;The number of outstanding Shares of the Issuer attributable to OPI VIII is 4,554,873 Shares. GP VIII, pursuant to its authority
under the limited partnership agreement of OPI VIII, may be considered to hold indirectly 4,554,873 Shares.</P>

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In addition to the relationships
between the Reporting Persons described in Items 2 and 5 above, OrbiMed Advisors is the managing member of GP VIII, pursuant to the terms
of the limited liability company agreement of GP&nbsp;VIII. Pursuant to this agreement and relationship, OrbiMed Advisors and GP VIII
have discretionary investment management authority with respect to the assets of OPI VIII. Such authority includes the power of GP VIII
to vote and otherwise dispose of securities held by OPI VIII.&nbsp;The number of outstanding Shares attributable to OPI VIII is 4,554,873
Shares.&nbsp;OrbiMed Advisors, pursuant to its authority under the terms of the limited liability company agreement of GP VIII may also
be considered to hold indirectly 4,554,873 Shares.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In addition to the relationships
between the Reporting Persons described in Items 2 and 5 above, Israel GP is the general partner of OIP II, pursuant to the terms of the
limited partnership agreement of OIP II, and Advisors II is the general partner of Israel GP, pursuant to the terms of the limited partnership
agreement of Israel GP. Pursuant to these agreements and relationships, Advisors II and Israel GP have discretionary investment management
authority with respect to the assets of OIP II. Such authority includes the power to vote and otherwise dispose of securities held by
OIP II. The number of outstanding Shares of the Issuer attributable to OIP II is 1,138,716 Shares. Israel GP, pursuant to its authority
under the limited partnership agreement of OIP II, and Advisors II, pursuant to its authority under the limited partnership agreement
of Israel GP, may each be considered to hold indirectly 1,138,716 Shares.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Erez Chimovits (&#8220;<U>Chimovits</U>&#8221;),
an employee of OrbiMed Advisors and a director of Advisors II, is a member of the Board of Directors of the Issuer and, accordingly, OrbiMed
Advisors, GP VIII, Advisors II, Israel GP may have the ability to affect and influence control of the Issuer. From time to time, Chimovits
may receive stock options or other awards of equity&#45;based compensation pursuant to the Issuer&#8217;s compensation arrangements for
non-employee directors. Pursuant to an agreement with OrbiMed Advisors, GP VIII, Advisors II, and Israel GP, Chimovits is obligated to
transfer any securities issued under any such stock options or other awards, or the economic benefit thereof, to OrbiMed Advisors, GP
VIII, Advisors II, and Israel GP, who will in turn ensure that such securities or economic benefits are provided to OPI VIII and OIP II.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0 10pt; background-color: white"><B><I>Investors&#8217; Rights Agreement</I></B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 10pt 0 0; text-align: justify; text-indent: 0.5in">In addition, OPI VIII,
OIP II, and certain other stockholders of the Issuer entered into an Amended and Restated Investors&#8217; Rights Agreement with the Issuer,
dated as of June 6, 2023 (the &#8220;<U>Investors&#8217; Rights Agreement</U>&#8221;). Pursuant to the Investors&#8217; Rights Agreement
and subject to the terms and conditions therein, the parties agreed that:</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; background-color: white"><I>Demand Registration Rights</I></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.25in; background-color: white">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in; background-color: white">At any
time beginning 180 days following the effective date of the registration statement of the IPO, the holders of at least a majority of the
Issuer&#8217;s registrable securities may request that the Issuer file a registration statement under the <FONT STYLE="background-color: white">Securities
Act of 1933, as amended (the &#8220;<U>Securities Act</U>&#8221;)</FONT> on a Form S-1 at the Issuer&#8217;s expense, subject to certain
exceptions, with an anticipated aggregate offering price, net of offering expenses, of not less than $5 million, in which case the Issuer
will be required to effect the registration as soon as practicable, and in any event within 60 days after the date of such registration
request. The Issuer is not obligated to effect more than two of these registrations.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; background-color: white"><I>Form S-3 Registration Rights</I></P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in; background-color: white">At any
time after the Issuer is qualified to file a registration statement on Form S-3 under the Securities Act, and subject to limitations and
conditions specified in the Investors&#8217; Rights Agreement, holders of at least 30% of the registrable securities under the Investors&#8217;
Rights Agreement may request that the Issuer prepare and file a registration statement on Form S-3 at the Issuer&#8217;s expense covering
the Shares of such holders having an anticipated aggregate offering price, net of offering expenses, of at least $1 million, in which
case the Issuer will be required to effect the registration as soon as practicable, and in any event within 45 days after receiving such
request. The Issuer is not obligated to effect more than one of these registrations in any 12-month period.</P>

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; background-color: white"><I>Piggyback Registration Rights</I></P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in; background-color: white"><FONT STYLE="background-color: white">Whenever
the Issuer proposes to file a registration statement under the Securities Act, other than with respect to certain excluded registrations,
OPI VIII and OIP II will each be entitled to notice of the registration and have the right, subject to limitations that the underwriters
may impose on the number of Shares included in the registration, to include the Shares held by them in the registration.</FONT></P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0 10pt; background-color: white"><B><I>Lock-Up Agreement</I></B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In addition, in connection with
the IPO, OPI VIII, OIP II, and Chimovits each entered into a lock-up agreement (the &#8220;<U>Lock&#45;Up Agreement</U>&#8221;) with the
Issuer&#8217;s underwriters pursuant to which, among other things, OPI VIII, OIP II, and Chimovits each agreed not to, except in limited
circumstances, directly or indirectly, from the date of the Lock-Up Agreement until 180 days after the date of the final prospectus supplement
relating to the IPO: (i)&nbsp;offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract
to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of any Shares or any securities convertible
into or exercisable or exchangeable for Shares; (ii) enter into any hedging, swap or other agreement or transaction that transfers, in
whole or in part, any of the economic consequences of ownership of the Shares or securities convertible into or exercisable or exchangeable
for Shares, whether settled by delivery of Shares, in cash or otherwise; (iii) make any demand for, or exercise any right with respect
to, the registration of any Shares or securities convertible into or exercisable or exchangeable for Shares; or (iv) publicly disclose
the intention to do any of the foregoing.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.25in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The foregoing description of the
Investors&#8217; Rights Agreement and the Lock-Up Agreement do not purport to be complete and are qualified in their entirety by reference
to the full text of the Investors&#8217; Rights Agreement and the Lock-Up Agreement, which are filed as Exhibits 2 and 3, respectively,
and incorporated herein by reference.</P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0"><B>Item 7.&nbsp; Material to Be Filed as Exhibits</B></P>

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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: top">
    <TD STYLE="width: 12%; border-top: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 4.5pt"><FONT STYLE="font-size: 10pt"><B>Exhibit</B></FONT></TD>
    <TD STYLE="width: 88%; border: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 4.5pt"><FONT STYLE="font-size: 10pt"><B>Description</B></FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 4.5pt"><FONT STYLE="font-size: 10pt">1.</FONT></TD>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 4.5pt; text-align: justify"><FONT STYLE="font-size: 10pt">Joint Filing Agreement among OrbiMed Advisors LLC, OrbiMed Capital GP VIII LLC, OrbiMed Advisors Israel II Limited, and OrbiMed Israel GP II, L.P.</FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 4.5pt"><FONT STYLE="font-size: 10pt">2.</FONT></TD>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 4.5pt; text-align: justify"><FONT STYLE="font-size: 10pt">Amended and Restated Investors&#8217; Rights Agreement, among the Issuer and certain of its stockholders, dated June 6, 2023 (incorporated by reference to Exhibit 4.2 to the Issuer&#8217;s Registration Statement on Form S-1/A (File No. 333-282197) filed with the SEC on October 7, 2024).</FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 4.5pt"><FONT STYLE="font-size: 10pt">3.</FONT></TD>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; font: 12pt Times New Roman, Times, Serif; padding: 4.5pt; text-align: justify"><FONT STYLE="font-size: 10pt">Form of Lock-Up Agreement (incorporated by reference to Exhibit A to Exhibit 1.1 to the Issuer&#8217;s Registration Statement on Form S-1/A (File No. 333-282197) filed with the SEC on October 7, 2024).</FONT></TD></TR>
  </TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0"><B>&nbsp;</B></P>

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

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

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

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

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

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

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

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

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

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    <DIV STYLE="break-before: page; margin-top: 6pt; margin-bottom: 6pt"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
    <!-- Field: /Page -->

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

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

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

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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 12pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: top">
    <TD><FONT STYLE="font-size: 10pt">Dated: October 17, 2024</FONT></TD>
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED ADVISORS LLC</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="width: 51%">&nbsp;</TD>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 34%">&nbsp;</TD>
    <TD STYLE="width: 9%">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt"><U>/s/ Carl L. Gordon&#9;</U></FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Name: Carl L. Gordon</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Title: Member </FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED CAPITAL GP VIII LLC</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED ADVISORS LLC, its managing member</FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt"><U>/s/ Carl L. Gordon&#9;</U></FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Name: Carl L. Gordon</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Title: Member of OrbiMed Advisors LLC</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED ADVISORS ISRAEL II LIMITED</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt"><U>/s/ Carl L. Gordon&#9;</U></FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Name: Carl L. Gordon</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Title: Director</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED ISRAEL GP II, L.P.</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED ADVISORS ISRAEL II LIMITED., its general partner</FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt"><U>/s/ Carl L. Gordon&#9;</U></FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Name: Carl L. Gordon</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Title: Director of OrbiMed Advisors Israel II Limited</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  </TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0"><B>&nbsp;</B></P>

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

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

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

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

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

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

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

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

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

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    <DIV STYLE="break-before: page; margin-top: 6pt; margin-bottom: 6pt"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0"><B>&nbsp;</B></P>

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

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

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

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"><FONT STYLE="font-size: 10pt">The
names and present principal occupations of each of the executive officers and directors of OrbiMed Advisors LLC are set forth below. Unless
otherwise noted, each of these persons is a United States citizen and has a business address of 601 Lexington Avenue, 54</FONT><FONT STYLE="font-size: 8pt">th</FONT>
<FONT STYLE="font-size: 10pt">Floor, New York, NY 10022.</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0.05in; text-align: justify; text-indent: 0.45in">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 12pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: top">
    <TD STYLE="width: 34%; padding-right: 0.25in"><FONT STYLE="font-size: 10pt"><U>Name</U></FONT></TD>
    <TD STYLE="width: 33%; padding-right: 0.25in"><FONT STYLE="font-size: 10pt"><U>Position with Reporting Person</U></FONT></TD>
    <TD STYLE="width: 33%; padding-right: 0.25in"><FONT STYLE="font-size: 10pt"><U>Principal Occupation</U></FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Carl L. Gordon</FONT></TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Member</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Member</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors LLC</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Sven H. Borho</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">German and Swedish Citizen</P></TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Member</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Member</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors LLC</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">W. Carter Neild</FONT></TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Member</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Member</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors LLC</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Geoffrey C. Hsu</FONT></TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Member</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Member</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors LLC</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">C. Scotland Stevens</FONT></TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Member</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Member</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors LLC</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">David P. Bonita</FONT></TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Member</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Member</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors LLC</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Peter A. Thompson</FONT></TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Member</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Member</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors LLC</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Matthew S. Rizzo</FONT></TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Member</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Member</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors LLC</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Trey Block</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Chief Financial Officer</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Chief Financial Officer</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors LLC</P></TD></TR>
  </TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

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

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

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

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

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

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

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

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

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

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

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

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    <DIV STYLE="break-before: page; margin-top: 6pt; margin-bottom: 6pt"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
    <!-- Field: /Page -->

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The business and operations of
OrbiMed Capital GP VIII LLC are managed by the executive officers and directors of its managing member, OrbiMed Advisors LLC, set forth
on Schedule I attached.</P>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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    <DIV STYLE="break-before: page; margin-top: 6pt; margin-bottom: 6pt"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The names and present principal
occupations of each of the executive officers and directors of OrbiMed Advisors Israel II Limited are set forth below. Unless otherwise
noted, each of these persons is a United States citizen and has a business address of 5 Hahoshlim Street, Building B, 1st Floor, Herzliya
Pituach, Israel.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0.05in; text-align: justify; text-indent: 0.45in">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 12pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: top">
    <TD STYLE="width: 34%; padding-right: 0.25in"><FONT STYLE="font-size: 10pt"><U>Name</U></FONT></TD>
    <TD STYLE="width: 33%; padding-right: 0.25in"><FONT STYLE="font-size: 10pt"><U>Position with Reporting Person</U></FONT></TD>
    <TD STYLE="width: 33%; padding-right: 0.25in"><FONT STYLE="font-size: 10pt"><U>Principal Occupation</U></FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Carl L. Gordon</FONT></TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Director</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Director</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors Israel II Limited</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">David P. Bonita</FONT></TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Director</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Director</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors Israel II Limited</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD>
    <TD STYLE="padding-right: 0.25in; text-align: justify">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.25in; text-align: justify"><FONT STYLE="font-size: 10pt">Erez Chimovits</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt">Director</FONT></TD>
    <TD>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">Director</P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0 0.25in 0 0; text-align: justify">OrbiMed Advisors Israel II Limited</P></TD></TR>
  </TABLE>
  <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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    <DIV STYLE="break-before: page; margin-top: 6pt; margin-bottom: 6pt"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
    <!-- Field: /Page -->

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

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The business and operations of
OrbiMed Israel GP II, L.P. are managed by the executive officers and directors of its general partner, OrbiMed Advisors Israel II Limited,
set forth on Schedule III attached.</P>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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    <DIV STYLE="break-before: page; margin-top: 6pt; margin-bottom: 6pt"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify">&nbsp;</P>

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

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 12pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: top">
    <TD STYLE="width: 12%; border-top: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 4.5pt"><FONT STYLE="font-size: 10pt"><B>Exhibit</B></FONT></TD>
    <TD STYLE="width: 88%; border: black 1.5pt solid; padding: 4.5pt"><FONT STYLE="font-size: 10pt"><B>Description</B></FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 4.5pt"><FONT STYLE="font-size: 10pt">1.</FONT></TD>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 4.5pt; text-align: justify"><FONT STYLE="font-size: 10pt">Joint Filing Agreement among OrbiMed Advisors LLC, OrbiMed Capital GP VIII LLC, OrbiMed Advisors Israel II Limited, and OrbiMed Israel GP II, L.P.</FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 4.5pt"><FONT STYLE="font-size: 10pt">2.</FONT></TD>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 4.5pt; text-align: justify"><FONT STYLE="font-size: 10pt">Amended and Restated Investors&#8217; Rights Agreement, among the Issuer and certain of its stockholders, dated June 6, 2023 (incorporated by reference to Exhibit 4.2 to the Issuer&#8217;s Registration Statement on Form S-1/A (File No. 333-282197) filed with the SEC on October 7, 2024).</FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 4.5pt"><FONT STYLE="font-size: 10pt">3.</FONT></TD>
    <TD STYLE="border-right: black 1.5pt solid; border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; padding: 4.5pt; text-align: justify"><FONT STYLE="font-size: 10pt">Form of Lock-Up Agreement (incorporated by reference to Exhibit A to Exhibit 1.1 to the Issuer&#8217;s Registration Statement on Form S-1/A (File No. 333-282197) filed with the SEC on October 7, 2024).</FONT></TD></TR>
  </TABLE>
<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0"></P>

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<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>


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<DOCUMENT>
<TYPE>EX-99.1
<SEQUENCE>2
<FILENAME>ss4005698_ex9901.htm
<DESCRIPTION>JOINT FILING AGREEMENT
<TEXT>
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<HEAD>
<TITLE></TITLE>
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<P STYLE="font: 12pt Times New Roman, Times, Serif; margin: 0">&nbsp;</P>

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

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.75in">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"><FONT STYLE="background-color: white">The
undersigned hereby agree that the Statement on Schedule&nbsp;13D, dated October 15, 2024, with respect to the common stock of Upstream
Bio, Inc. is filed on behalf of each of us pursuant to and in accordance with the provisions of Rule&nbsp;13d-1(k) under the Securities
Exchange Act of 1934, as amended. Each of the undersigned agrees to be responsible for the timely filing of this Statement, and for the
completeness and accuracy of the information concerning itself contained therein. This Joint Filing Agreement may be executed in any number
of counterparts, all of which taken together shall constitute one and the same instrument.</FONT></P>

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

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">IN WITNESS WHEREOF, the undersigned have executed this
Joint Filing Agreement as of the 17th day of October, 2024.</P>

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

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 12pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED ADVISORS LLC</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="width: 50%">&nbsp;</TD>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 35%">&nbsp;</TD>
    <TD STYLE="width: 9%">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt"><U>/s/ Carl L. Gordon&#9;</U></FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Name: Carl L. Gordon</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Title: Member </FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED CAPITAL GP VIII LLC</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED ADVISORS LLC, its managing member</FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt"><U>/s/ Carl L. Gordon&#9;</U></FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Name: Carl L. Gordon</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Title: Member of OrbiMed Advisors LLC</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED ADVISORS ISRAEL II LIMITED</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt"><U>/s/ Carl L. Gordon&#9;</U></FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Name: Carl L. Gordon</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Title: Director</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED ISRAEL GP II, L.P.</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">ORBIMED ADVISORS ISRAEL II LIMITED, its general partner</FONT></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt"><U>/s/ Carl L. Gordon&#9;</U></FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Name: Carl L. Gordon</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Title: Director of OrbiMed Advisors Israel II Limited</FONT></TD>
    <TD>&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
  </TABLE>
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