<SEC-DOCUMENT>0001567619-21-005402.txt : 20210302
<SEC-HEADER>0001567619-21-005402.hdr.sgml : 20210302
<ACCEPTANCE-DATETIME>20210302170720
ACCESSION NUMBER:		0001567619-21-005402
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210226
FILED AS OF DATE:		20210302
DATE AS OF CHANGE:		20210302

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Peterson Amy C.
		CENTRAL INDEX KEY:			0001682735

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37587
		FILM NUMBER:		21704977

	MAIL ADDRESS:	
		STREET 1:		C/O MOURANT OZANNES CORPORATE SERVICES
		STREET 2:		94 SOLARIS AVENUE
		CITY:			CAMANA BAY, GRAND CAYMAN
		STATE:			E9
		ZIP:			KY1-1108

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CytomX Therapeutics, Inc.
		CENTRAL INDEX KEY:			0001501989
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				273521219
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		151 OYSTER POINT BLVD.
		STREET 2:		SUITE 400
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080
		BUSINESS PHONE:		650.515.3185

	MAIL ADDRESS:	
		STREET 1:		151 OYSTER POINT BLVD.
		STREET 2:		SUITE 400
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-02-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001501989</issuerCik>
        <issuerName>CytomX Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>CTMX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001682735</rptOwnerCik>
            <rptOwnerName>Peterson Amy C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CYTOMX THERAPEUTICS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>151 OYSTER POINT BLVD., STE. 400</rptOwnerStreet2>
            <rptOwnerCity>SOUTH SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94080</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, Chief Development Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>7.85</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-02-26</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>250000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2031-02-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>250000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>250000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">1/48th of the shares subject to the option vest on each monthly anniversary measured from February 26, 2021 (the &quot;Vesting Commencement Date&quot;), such that 100% of the shares subject to the option will be fully vested and exercisable on the fourth anniversary of the Vesting Commencement Date, subject to the Reporting Person's continued service to the Issuer through each such date.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Lloyd Rowland, as Attorney-in-Fact for Amy C. Peterson</signatureName>
        <signatureDate>2021-03-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
