<SEC-DOCUMENT>0001415889-25-004199-index.html : 20250214
<SEC-HEADER>0001415889-25-004199.hdr.sgml : 20250214
<ACCEPTANCE-DATETIME>20250214173841
ACCESSION NUMBER:		0001415889-25-004199
CONFORMED SUBMISSION TYPE:	SCHEDULE 13G
PUBLIC DOCUMENT COUNT:		2
FILED AS OF DATE:		20250214
DATE AS OF CHANGE:		20250214

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:		SCHEDULE 13G
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-94651
		FILM NUMBER:		25631329

	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:			Decheng Capital Global Life Sciences Fund IV, L.P.
		CENTRAL INDEX KEY:			0001834150
		ORGANIZATION NAME:           	
		IRS NUMBER:				981568621
		STATE OF INCORPORATION:			E9
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SCHEDULE 13G

	BUSINESS ADDRESS:	
		STREET 1:		C/O MAPLES CORPORATE SERVICES LIMITED
		STREET 2:		UGLAND HOUSE, P.O. BOX 309
		CITY:			GRAND CAYMAN
		STATE:			E9
		ZIP:			KY1-1104
		BUSINESS PHONE:		345-949-8066

	MAIL ADDRESS:	
		STREET 1:		C/O MAPLES CORPORATE SERVICES LIMITED
		STREET 2:		UGLAND HOUSE, P.O. BOX 309
		CITY:			GRAND CAYMAN
		STATE:			E9
		ZIP:			KY1-1104
</SEC-HEADER>
<DOCUMENT>
<TYPE>SCHEDULE 13G
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
Document 1 - file: primary_doc.html

Document 1 - RAW XML: primary_doc.xml

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-99.1
<SEQUENCE>2
<FILENAME>ex-99-02142025_100239.htm
<DESCRIPTION>JOINT FILING AGREEMENT
<TEXT>
Document 2 - file: ex-99-02142025_100239.htm

</DOCUMENT>
</SEC-DOCUMENT>