<SEC-DOCUMENT>0001193125-24-234371.txt : 20241108
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<ACCEPTANCE-DATETIME>20241008160129
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ACCESSION NUMBER:		0001193125-24-234371
CONFORMED SUBMISSION TYPE:	CORRESP
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20241008

FILER:

	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:		CORRESP

	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
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<TYPE>CORRESP
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<Center><DIV STYLE="width:8.5in" align="left">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>VIA EDGAR </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">October&nbsp;8, 2024 </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">United States Securities and Exchange
Commission </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Division of Corporation Finance </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Office of Life
Sciences </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">100 F. Street, N.E. </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Washington, D.C. 20549 </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Attention: Chris Edwards, Jimmy McNamara, Kevin Kuhar and Franklin Wyman </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top"><B>Re:</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"><B>Upstream Bio, Inc.</B></TD></TR>
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<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"><B>Acceleration Request for Registration Statement on Form <FONT STYLE="white-space:nowrap">S-1</FONT></B></TD></TR>
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<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"><B>File <FONT STYLE="white-space:nowrap">No.&nbsp;333-282197</FONT></B></TD></TR>
</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Dear Ladies and Gentlemen, </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Pursuant to Rule 461 under the Securities Act of 1933, as amended (the &#147;<B>Act</B>&#148;), Upstream Bio, Inc. (the
&#147;<B>Company</B>&#148;) hereby requests that the effective date of the above-referenced registration statement (the &#147;<B>Registration Statement</B>&#148;) be accelerated to October&nbsp;10, 2024 at 4:01 p.m. Eastern Time, or as soon
thereafter as practicable, unless we or our outside counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared effective at some other time. In making this acceleration request, the Company acknowledges that it
is aware of its responsibilities under the Act. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Once the Registration Statement is effective, please orally confirm the event with our
counsel, Goodwin Procter LLP, by calling Gabriela Morales-Rivera at (617) <FONT STYLE="white-space:nowrap">570-1329.</FONT> </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">If you have
any questions regarding this request, please contact Gabriela Morales-Rivera of Goodwin Procter LLP at (617) <FONT STYLE="white-space:nowrap">570-1329.</FONT> </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">Sincerely, </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">UPSTREAM BIO, INC.
</P> <P STYLE="margin-top:12pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman"><U>/s/ E. Rand Sutherland</U> </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">E. Rand Sutherland </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">Chief
Executive Officer </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">cc:</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">E. Rand Sutherland, M.D., M.P.H., <I>Upstream Bio, Inc.</I> </P></TD></TR></TABLE>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">Michael Paul Gray, M.B.A., <I>Upstream Bio, Inc.</I> </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">Gabriela <FONT STYLE="white-space:nowrap">Morales-Rivera,</FONT> Esq., <I>Goodwin Procter LLP</I> </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">William D. Collins, Esq., <I>Goodwin Procter LLP</I> </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">Kathryn W. Clerici, Esq., <I>Goodwin Procter LLP</I> </P>
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