<SEC-DOCUMENT>0000899243-19-009671.txt : 20190402
<SEC-HEADER>0000899243-19-009671.hdr.sgml : 20190402
<ACCEPTANCE-DATETIME>20190402200407
ACCESSION NUMBER:		0000899243-19-009671
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190313
FILED AS OF DATE:		20190402
DATE AS OF CHANGE:		20190402

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Bridger Gary
		CENTRAL INDEX KEY:			0001600049

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38295
		FILM NUMBER:		19727177

	MAIL ADDRESS:	
		STREET 1:		C/O FIVE CORNERS CAPITAL
		STREET 2:		700 WEST GEORGIA STREET, SUITE 2500
		CITY:			VANCOUVER
		STATE:			A1
		ZIP:			V7Y 1B3

ISSUER:		

	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

	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>4/A
<SEQUENCE>1
<FILENAME>doc4a.xml
<DESCRIPTION>FORM 4/A SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2019-03-13</periodOfReport>

    <dateOfOriginalSubmission>2019-03-14</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001501697</issuerCik>
        <issuerName>X4 Pharmaceuticals, Inc</issuerName>
        <issuerTradingSymbol>XFOR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001600049</rptOwnerCik>
            <rptOwnerName>Bridger Gary</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O X4 PHARMACEUTICALS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>955 MASSACHUSETTS AVENUE, 4TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02139</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>10.44</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2019-03-13</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>21570</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2028-10-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>21570</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>21570</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>18.66</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2019-03-13</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>6854</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2029-03-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6854</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6854</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Twenty-five percent (25%) of the shares subject to the option vested on October 4, 2019, and one thirty-sixth (1/36th) of the shares subject to the option shall vest each month thereafter, subject to the Reporting Person continuing to provide service through each such date.</footnote>
        <footnote id="F2">Reflects the Reporting Person's stock option to acquire 226,983 shares of X4 common stock for $0.99 per share that was assumed by the Issuer in the merger of Artemis AC Corp., a wholly-owned subsidiary of the Issuer, with and into X4 Therapeutics, Inc. (formerly X4 Pharmaceuticals, Inc.) (&quot;X4&quot;) on March 13, 2019 (the &quot;Merger&quot;).</footnote>
        <footnote id="F3">33.3333% of the shares subject to the option shall vest on March 13, 2020, with the remainder vesting in equal monthly installments of 2.7777% of the shares subject to the option until the 36-month anniversary of the date of the award, subject to the Reporting Person continuing to provide service through each such date. This amendment is being filed solely to report this additional stock option grant, which was granted automatically on March 13, 2019 pursuant to the Issuer's Director Compensation Policy upon such Reporting Person's election to the Board of Directors of the Issuer in connection with the closing of the Merger.</footnote>
    </footnotes>

    <remarks>All share and per share amounts of the Issuer's common stock and stock options reported in this Form 4/A reflect the 1-for-6 reverse stock split of the Issuer's common stock effected on March 13, 2019 after the completion of the Merger.</remarks>

    <ownerSignature>
        <signatureName>/s/ Adam S. Mostafa, attorney-in-fact</signatureName>
        <signatureDate>2019-04-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
