<SEC-DOCUMENT>0000899243-21-041081.txt : 20211021
<SEC-HEADER>0000899243-21-041081.hdr.sgml : 20211021
<ACCEPTANCE-DATETIME>20211021204052
ACCESSION NUMBER:		0000899243-21-041081
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20211021
FILED AS OF DATE:		20211021
DATE AS OF CHANGE:		20211021

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			RiverVest Venture Fund IV, L.P.
		CENTRAL INDEX KEY:			0001725443
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-40925
		FILM NUMBER:		211338423

	BUSINESS ADDRESS:	
		STREET 1:		101 SOUTH HANLEY ROAD, SUITE 1850
		CITY:			ST. LOUIS
		STATE:			MO
		ZIP:			63105
		BUSINESS PHONE:		(314) 726-6700

	MAIL ADDRESS:	
		STREET 1:		101 SOUTH HANLEY ROAD, SUITE 1850
		CITY:			ST. LOUIS
		STATE:			MO
		ZIP:			63105

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Xilio Therapeutics, Inc.
		CENTRAL INDEX KEY:			0001840233
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				851623397
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		828 WINTER STREET
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451
		BUSINESS PHONE:		617-833-1027

	MAIL ADDRESS:	
		STREET 1:		828 WINTER STREET
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc3.xml
<DESCRIPTION>FORM 3 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2021-10-21</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001840233</issuerCik>
        <issuerName>Xilio Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>XLO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001725443</rptOwnerCik>
            <rptOwnerName>RiverVest Venture Fund IV, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>101 S. HANLEY ROAD, SUITE 1850</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ST. LOUIS</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>63105</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Series B Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>832120</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series C Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>359324</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each share of Series B Preferred Stock and Series C Preferred Stock has no expiration date and are convertible at any time at the election of the holder without payment of further consideration.  Each share of Series B Preferred Stock and Series C Preferred Stock will automatically convert into one share of Common Stock upon the closing of the Issuer's initial public offering.</footnote>
        <footnote id="F2">The shares held by RiverVest Venture Fund IV, L.P. (&quot;RiverVest IV&quot;) are indirectly held by RiverVest Venture Partners IV, L.P. (&quot;RiverVest Partners IV&quot;), which is the general partner of RiverVest IV. RiverVest Venture Partners IV, LLC is the general partner of RiverVest Partners IV.</footnote>
        <footnote id="F3">The individual managers of RiverVest Ventures Partners IV, LLC are Jay Schmelter, John P. McKearn, Ph.D. and Niall O'Donnell. RiverVest Partners IV, RiverVest Venture Partners IV, LLC and each of the individual managers share voting and dispositive power with regard to the securities directly held by RiverVest Venture Fund IV, L.P.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jay Schmelter, Manager of RiverVest Venture Partners IV, LLC</signatureName>
        <signatureDate>2021-10-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
