<SEC-DOCUMENT>0001193125-19-106612-index.html : 20190415
<SEC-HEADER>0001193125-19-106612.hdr.sgml : 20190415
<ACCEPTANCE-DATETIME>20190415163846
ACCESSION NUMBER:		0001193125-19-106612
CONFORMED SUBMISSION TYPE:	424B5
PUBLIC DOCUMENT COUNT:		3
FILED AS OF DATE:		20190415
DATE AS OF CHANGE:		20190415

FILER:

	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:		424B5
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	333-229377
		FILM NUMBER:		19748987

	BUSINESS ADDRESS:	
		STREET 1:		955 MASSACHUSETTS AVENUE
		STREET 2:		4TH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		857-529-8300

	MAIL ADDRESS:	
		STREET 1:		955 MASSACHUSETTS AVENUE
		STREET 2:		4TH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Arsanis, Inc.
		DATE OF NAME CHANGE:	20100920
</SEC-HEADER>
<DOCUMENT>
<TYPE>424B5
<SEQUENCE>1
<FILENAME>d715130d424b5.htm
<DESCRIPTION>424B5
<TEXT>
Document 1 - file: d715130d424b5.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>2
<FILENAME>g715130g05r47.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 2 - file: g715130g05r47.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>3
<FILENAME>g715130g30u90.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 3 - file: g715130g30u90.jpg

</DOCUMENT>
</SEC-DOCUMENT>