<SEC-DOCUMENT>0001209191-21-003422.txt : 20210113
<SEC-HEADER>0001209191-21-003422.hdr.sgml : 20210113
<ACCEPTANCE-DATETIME>20210113162039
ACCESSION NUMBER:		0001209191-21-003422
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210111
FILED AS OF DATE:		20210113
DATE AS OF CHANGE:		20210113

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Thomas Dolca
		CENTRAL INDEX KEY:			0001768239

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38692
		FILM NUMBER:		21526305

	MAIL ADDRESS:	
		STREET 1:		C/O PRINCIPIA BIOPHARMA INC.
		STREET 2:		220 E. GRAND AVENUE
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Equillium, Inc.
		CENTRAL INDEX KEY:			0001746466
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				821554746
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2223 AVENIDA DE LA PLAYA
		STREET 2:		SUITE 105
		CITY:			LA JOLLA
		STATE:			CA
		ZIP:			92037
		BUSINESS PHONE:		(858) 412-5302

	MAIL ADDRESS:	
		STREET 1:		2223 AVENIDA DE LA PLAYA
		STREET 2:		SUITE 105
		CITY:			LA JOLLA
		STATE:			CA
		ZIP:			92037
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-01-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001746466</issuerCik>
        <issuerName>Equillium, Inc.</issuerName>
        <issuerTradingSymbol>EQ</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001768239</rptOwnerCik>
            <rptOwnerName>Thomas Dolca</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2223 AVENIDA DE LA PLAYA, SUITE 105</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LA JOLLA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92037</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Medical Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>5.20</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-01-11</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>450000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2031-01-10</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>450000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>450000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Twenty-five percent of the shares subject to the option vests on the first anniversary of the vesting commencement date, and the remainder vests in 36 equal monthly installments thereafter for the following three years.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jason A. Keyes, Attorney-in-Fact</signatureName>
        <signatureDate>2021-01-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
