<SEC-DOCUMENT>0001104659-21-005950.txt : 20210120
<SEC-HEADER>0001104659-21-005950.hdr.sgml : 20210120
<ACCEPTANCE-DATETIME>20210120190440
ACCESSION NUMBER:		0001104659-21-005950
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20210115
FILED AS OF DATE:		20210120
DATE AS OF CHANGE:		20210120

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Kaufman Michael J.
		CENTRAL INDEX KEY:			0001709996

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38129
		FILM NUMBER:		21539996

	MAIL ADDRESS:	
		STREET 1:		840 MEMORIAL DRIVE
		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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    <documentType>4</documentType>

    <periodOfReport>2021-01-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001442836</issuerCik>
        <issuerName>Mersana Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>MRSN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001709996</rptOwnerCik>
            <rptOwnerName>Kaufman Michael J.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MERSANA THERAPEUTICS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>840 MEMORIAL DRIVE</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02139</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr VP, Chemistry, Man.&amp;Control</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-01-15</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
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                <sharesOwnedFollowingTransaction>
                    <value>6667</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
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        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-01-15</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1957</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>21.09</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4710</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
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                <directOrIndirectOwnership>
                    <value>D</value>
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    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
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            <transactionDate>
                <value>2021-01-15</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>6667</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6667</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20000</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>21.09</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-01-15</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>112500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2031-01-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>112500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>112500</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        <derivativeTransaction>
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                <value>Restricted Stock Units</value>
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                <footnoteId id="F1"/>
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            <transactionDate>
                <value>2021-01-15</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>25000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
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                <footnoteId id="F5"/>
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            <expirationDate>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>25000</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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    </derivativeTable>

    <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 settlement.</footnote>
        <footnote id="F2">Represents the number of shares of common stock that have been withheld by the Issuer to satisfy its income tax withholding and remittance obligations in connection with the net settlement of the RSUs and does not represent a sale by the reporting person.</footnote>
        <footnote id="F3">25% of the total number of RSUs vested on January 15, 2021, 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 15, 2021.</footnote>
        <footnote id="F5">The restricted stock units vest in equal annual installments over the first four years after the vesting commencement date, January 15, 2021.</footnote>
    </footnotes>

    <remarks>Exhibit 24 - Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Brian DeSchuytner, as Attorney-in-Fact</signatureName>
        <signatureDate>2021-01-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
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<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>tm211948-10_ex24.htm
<DESCRIPTION>EXHIBIT 24
<TEXT>
<HTML>
<HEAD>
     <TITLE></TITLE>
</HEAD>
<BODY STYLE="font: 10pt Times New Roman, Times, Serif">

<P STYLE="text-align: right; margin: 0"><B>Exhibit 24</B></P>

<P STYLE="margin: 0; text-align: right">&nbsp;</P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">POWER OF ATTORNEY</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">The undersigned hereby
constitutes and appoints Anna Protopapas, Brian DeSchuytner, and Jonathan Owen, with full power of substitution, as the undersigned&rsquo;s
true and lawful attorney-in-fact to:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.5in"></TD><TD STYLE="width: 0.5in">(1)</TD><TD STYLE="text-align: justify">prepare, execute in the undersigned&rsquo;s name and on the undersigned&rsquo;s behalf, and submit
to the U.S. Securities and Exchange Commission (the &ldquo;SEC&rdquo;) a Form ID, including amendments thereto, and any other documents
necessary or appropriate to obtain codes and passwords enabling the undersigned to make electronic filings with the SEC of reports
required by Section 16(a) of the Securities Exchange Act of 1934, as amended, or any rule or regulation of the SEC;</TD></TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 1in; text-align: justify; text-indent: -0.5in">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.5in"></TD><TD STYLE="width: 0.5in">(2)</TD><TD STYLE="text-align: justify">execute for and on behalf of the undersigned, in the undersigned&rsquo;s capacity as officer and/or
director of Mersana Therapeutics, Inc. (the &ldquo;Company&rdquo;), Forms 3, 4, and 5 in accordance with Section 16(a) of the Securities
Exchange Act of 1934, as amended, and the rules thereunder;</TD></TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 1in; text-align: justify; text-indent: -0.5in">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.5in"></TD><TD STYLE="width: 0.5in">(3)</TD><TD STYLE="text-align: justify">do and perform any and all acts for and on behalf of the undersigned that may be necessary or desirable
to complete and execute any such Form 3, 4, or 5, complete and execute any amendment or amendments thereto, and timely file such
form with the SEC and any stock exchange or similar authority; and</TD></TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 1in; text-align: justify; text-indent: -0.5in">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0.5in"></TD><TD STYLE="width: 0.5in">(4)</TD><TD STYLE="text-align: justify">take any other action of any type whatsoever in connection with the foregoing that, in the opinion
of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood
that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in
such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact&rsquo;s discretion.</TD></TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">The undersigned hereby
grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary,
or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the
undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming
all that such attorney-in-fact, or such attorney-in-fact&rsquo;s substitute or substitutes, shall lawfully do or cause to be done
by virtue of this power of attorney and the rights and powers herein granted. The undersigned acknowledges that the foregoing attorneys-in-fact,
in serving in such capacity at the request of the undersigned, are not assuming, nor is the Company assuming, any of the undersigned&rsquo;s
responsibilities to comply with Section 16 of the Securities Exchange Act of 1934, as amended.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">This Power of Attorney
shall remain in full force and effect until the undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned&rsquo;s holdings of and transactions in securities issued by the Company, unless earlier revoked by the undersigned
in a signed writing delivered to the foregoing attorney-in-fact.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; text-indent: 0.5in">[<I>Remainder of page intentionally left blank</I>]</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">IN WITNESS WHEREOF,
the undersigned has caused this Power of Attorney to be executed as of this 9<SUP>th</SUP> day of October, 2020.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="border-collapse: collapse; width: 100%">
<TR STYLE="vertical-align: bottom">
    <TD STYLE="font: 10pt Times New Roman, Times, Serif; width: 50%">&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid; font: 10pt Times New Roman, Times, Serif; width: 50%">/s/ Michael Kaufman </TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="font: 10pt Times New Roman, Times, Serif">&nbsp;</TD>
    <TD STYLE="font: 10pt Times New Roman, Times, Serif">Michael Kaufman, Ph.D.</TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">[Signature Page to Limited Power of Attorney]</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

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    <!-- Field: /Page -->

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

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</TEXT>
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