<SEC-DOCUMENT>0001209191-20-025655.txt : 20200424
<SEC-HEADER>0001209191-20-025655.hdr.sgml : 20200424
<ACCEPTANCE-DATETIME>20200424173054
ACCESSION NUMBER:		0001209191-20-025655
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20200422
FILED AS OF DATE:		20200424
DATE AS OF CHANGE:		20200424

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Zedelmayer Christine
		CENTRAL INDEX KEY:			0001797818

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38692
		FILM NUMBER:		20816284

	MAIL ADDRESS:	
		STREET 1:		2223 AVENIDA DE LA PLAYA, SUITE 105
		CITY:			LA JOLLA
		STATE:			CA
		ZIP:			92037

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>2020-04-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001797818</rptOwnerCik>
            <rptOwnerName>Zedelmayer Christine</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>Sr. Vice President and COO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>3.87</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-04-22</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
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                <transactionCode>D</transactionCode>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>35695</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
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            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2028-09-12</value>
            </expirationDate>
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                    <value>Common Stock</value>
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            <securityTitle>
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            </securityTitle>
            <conversionOrExercisePrice>
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            <transactionDate>
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            <deemedExecutionDate></deemedExecutionDate>
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            <transactionTimeliness>
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        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>7.16</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-04-22</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
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                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>50000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2029-02-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>50000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.45</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-04-22</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>50000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2029-02-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>50000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>50000</value>
                </sharesOwnedFollowingTransaction>
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                    <value>D</value>
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        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.75</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-04-22</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>90000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
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            <expirationDate>
                <value>2029-12-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
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            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
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                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.45</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-04-22</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>90000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
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            <expirationDate>
                <value>2029-12-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
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                <underlyingSecurityShares>
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            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>90000</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </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>
        <footnote id="F2">Effective April 22, 2020, the Board of Directors of the Company approved an option repricing which resulted in, for purposes of Section 16 of the Exchange Act, the cancellation of this option granted to her on September 13, 2018, in exchange for a new option having a lower exercise price of $2.45 per share, which is the closing price of the Company's common stock on April 22, 2020.  All of the other terms of the option remained unchanged.</footnote>
        <footnote id="F3">Effective April 22, 2020, the Board of Directors of the Company approved an option repricing which resulted in, for purposes of Section 16 of the Exchange Act, the cancellation of this option granted to her on February 13, 2019, in exchange for a new option having a lower exercise price of $2.45 per share, which is the closing price of the Company's common stock on April 22, 2020.  All of the other terms of the option remained unchanged.</footnote>
        <footnote id="F4">Effective April 22, 2020, the Board of Directors of the Company approved an option repricing which resulted in, for purposes of Section 16 of the Exchange Act, the cancellation of this option granted to her on December 10, 2019, in exchange for a new option having a lower exercise price of $2.45 per share, which is the closing price of the Company's common stock on April 22, 2020.  All of the other terms of the option remained unchanged.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jason A. Keyes, Attorney-in-Fact</signatureName>
        <signatureDate>2020-04-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
