<SEC-DOCUMENT>0001209191-23-045444.txt : 20230811
<SEC-HEADER>0001209191-23-045444.hdr.sgml : 20230811
<ACCEPTANCE-DATETIME>20230811163147
ACCESSION NUMBER:		0001209191-23-045444
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20230809
FILED AS OF DATE:		20230811
DATE AS OF CHANGE:		20230811

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Novo Holdings A/S
		CENTRAL INDEX KEY:			0001388325
		STATE OF INCORPORATION:			G7
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-41008
		FILM NUMBER:		231164617

	BUSINESS ADDRESS:	
		STREET 1:		TUBORG HAVNEVEJ 19
		CITY:			HELLERUP
		STATE:			G7
		ZIP:			2900
		BUSINESS PHONE:		45 8824 8824

	MAIL ADDRESS:	
		STREET 1:		TUBORG HAVNEVEJ 19
		CITY:			HELLERUP
		STATE:			G7
		ZIP:			2900

	FORMER NAME:	
		FORMER CONFORMED NAME:	Novo A/S
		DATE OF NAME CHANGE:	20070130

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			IO Biotech, Inc.
		CENTRAL INDEX KEY:			0001865494
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				870909276
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		OLE MAALOES VEH 3
		CITY:			COPENHAGEN
		STATE:			G7
		ZIP:			2200
		BUSINESS PHONE:		4570702980

	MAIL ADDRESS:	
		STREET 1:		OLE MAALOES VEH 3
		CITY:			COPENHAGEN
		STATE:			G7
		ZIP:			2200
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-08-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001865494</issuerCik>
        <issuerName>IO Biotech, Inc.</issuerName>
        <issuerTradingSymbol>IOBT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001388325</rptOwnerCik>
            <rptOwnerName>Novo Holdings A/S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>TUBORG HAVNEVEJ 19</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HELLERUP</rptOwnerCity>
            <rptOwnerState>G7</rptOwnerState>
            <rptOwnerZipCode>2900</rptOwnerZipCode>
            <rptOwnerStateDescription>DENMARK</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2023-08-09</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2469135</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.025</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5707467</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Common Stock Warrant (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.47</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2023-08-09</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2469135</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.025</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2023-08-09</value>
            </exerciseDate>
            <expirationDate>
                <value>2027-02-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2469135</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2469135</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents a combined purchase price of $2.025 for Common Stock and Warrants from Issuer in a private placement.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Barbara Fiorini Due, General Counsel, Finance &amp; Operations of Novo Holdings A/S</signatureName>
        <signatureDate>2023-08-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
