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ACCESSION NUMBER:		9999999997-24-004125
CONFORMED SUBMISSION TYPE:	SEC STAFF LETTER
CATEGORY:             	REDACTED EXHIBIT
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20241016
ACTION DATE:               	20241016
RECEIVED DATE:           	20241017

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:		SEC STAFF LETTER

	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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<FILENAME>filename1.pdf
<TEXT>
Document 1 - file: filename1.pdf

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