<SEC-DOCUMENT>0001140361-17-021016.txt : 20170516
<SEC-HEADER>0001140361-17-021016.hdr.sgml : 20170516
<ACCEPTANCE-DATETIME>20170516165743
ACCESSION NUMBER:		0001140361-17-021016
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170512
FILED AS OF DATE:		20170516
DATE AS OF CHANGE:		20170516

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

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Goeltz II Robert C.
		CENTRAL INDEX KEY:			0001653881

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37587
		FILM NUMBER:		17849353

	MAIL ADDRESS:	
		STREET 1:		343 OYSTER POINT BLVD
		STREET 2:		SUITE 100
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
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    <periodOfReport>2017-05-12</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001653881</rptOwnerCik>
            <rptOwnerName>Goeltz II Robert C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>151 OYSTER POINT BLVD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 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>Chief Financial Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-05-12</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>9980</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4.4728</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>22769</value>
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        </nonDerivativeTransaction>
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    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
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                <value>4.4728</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-05-12</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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                <transactionShares>
                    <value>9980</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <exerciseDate>
                <footnoteId id="F1"/>
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            <expirationDate>
                <value>2025-05-06</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
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            <expirationDate>
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            </expirationDate>
            <underlyingSecurity>
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                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">This option vests 25% on May 4, 2016, and the remaining 75% vests in 36 substantially equal monthly installments thereafter, with each additional installment vesting on the last day of the month, except the final installment, which shall vest on May 4, 2019.</footnote>
        <footnote id="F2">This option vests in 48 substantially equal monthly installments starting on August 28, 2015, with each additional installment vesting on the last day of the month starting in September 2015.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Cynthia J. Ladd, as Attorney-in-Fact for Robert C. Goeltz II</signatureName>
        <signatureDate>2017-05-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
