<SEC-DOCUMENT>0001193125-24-234371-index.html : 20241108
<SEC-HEADER>0001193125-24-234371.hdr.sgml : 20241108
<ACCEPTANCE-DATETIME>20241008160129
<PRIVATE-TO-PUBLIC>
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
</SEC-HEADER>
<DOCUMENT>
<TYPE>CORRESP
<SEQUENCE>1
<FILENAME>filename1.htm
<TEXT>
Document 1 - file: filename1.htm

</DOCUMENT>
</SEC-DOCUMENT>