<SEC-DOCUMENT>0001104659-22-005548.txt : 20220119
<SEC-HEADER>0001104659-22-005548.hdr.sgml : 20220119
<ACCEPTANCE-DATETIME>20220119180130
ACCESSION NUMBER:		0001104659-22-005548
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20220114
FILED AS OF DATE:		20220119
DATE AS OF CHANGE:		20220119

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Protopapas Anna
		CENTRAL INDEX KEY:			0001347582

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38129
		FILM NUMBER:		22539941

	MAIL ADDRESS:	
		STREET 1:		MILLENNIUM PHARMACEUTICALS, INC.
		STREET 2:		40 LANDSDOWNE STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Mersana Therapeutics, Inc.
		CENTRAL INDEX KEY:			0001442836
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		840 MEMORIAL DRIVE
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		617-498-0020

	MAIL ADDRESS:	
		STREET 1:		840 MEMORIAL DRIVE
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MERSANA THERAPEUTICS INC
		DATE OF NAME CHANGE:	20080813
</SEC-HEADER>
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        <issuerName>Mersana Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>MRSN</issuerTradingSymbol>
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            <rptOwnerName>Protopapas Anna</rptOwnerName>
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            <rptOwnerState>MA</rptOwnerState>
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            <otherText></otherText>
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    <footnotes>
        <footnote id="F1">Each restricted stock unit (&quot;RSU&quot;) represents a contingent right to receive one share of the Issuer's common stock upon vesting.</footnote>
        <footnote id="F2">50% of the total number of RSUs vested as of January 14, 2022, and thereafter shall vest in equal annual installments over the next two years.</footnote>
        <footnote id="F3">25% of the total number of RSUs vested on January 14, 2022, and thereafter shall vest in equal annual installments over the next three years.</footnote>
        <footnote id="F4">The option vests in equal quarterly installments over the first four years after the vesting commencement date, January 14, 2022.</footnote>
        <footnote id="F5">The restricted stock units vest in equal annual installments over the first four years after the vesting commencement date, January 14, 2022.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Brian DeSchuytner, as Attorney-in-Fact</signatureName>
        <signatureDate>2022-01-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</SEC-DOCUMENT>
