<SEC-DOCUMENT>0001104659-21-024246-index.html : 20210216
<SEC-HEADER>0001104659-21-024246.hdr.sgml : 20210216
<ACCEPTANCE-DATETIME>20210216163936
ACCESSION NUMBER:		0001104659-21-024246
CONFORMED SUBMISSION TYPE:	SC 13G/A
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20210216
DATE AS OF CHANGE:		20210216
GROUP MEMBERS:		PETER KOLCHINSKY
GROUP MEMBERS:		RA CAPITAL HEALTHCARE FUND, L.P.
GROUP MEMBERS:		RAJEEV SHAH

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			X4 Pharmaceuticals, Inc
		CENTRAL INDEX KEY:			0001501697
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				273181608
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-90199
		FILM NUMBER:		21639680

	BUSINESS ADDRESS:	
		STREET 1:		61 NORTH BEACON STREET
		STREET 2:		4TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02134
		BUSINESS PHONE:		857-529-8300

	MAIL ADDRESS:	
		STREET 1:		61 NORTH BEACON STREET
		STREET 2:		4TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02134

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Arsanis, Inc.
		DATE OF NAME CHANGE:	20100920

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			RA CAPITAL MANAGEMENT, L.P.
		CENTRAL INDEX KEY:			0001346824
		IRS NUMBER:				830406777
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G/A

	BUSINESS ADDRESS:	
		STREET 1:		200 BERKELEY STREET, 18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		617-778-2500

	MAIL ADDRESS:	
		STREET 1:		200 BERKELEY STREET, 18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	RA CAPITAL MANAGEMENT, LLC
		DATE OF NAME CHANGE:	20051213
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13G/A
<SEQUENCE>1
<FILENAME>tm216584d35_sc13ga.htm
<DESCRIPTION>SC 13G/A
<TEXT>
Document 1 - file: tm216584d35_sc13ga.htm

</DOCUMENT>
</SEC-DOCUMENT>