Exhibit 4.1


 


MERSANA THERAPEUTICS, INC.


 


WARRANT TO PURCHASE COMMON STOCK


 


	 	 	Number of Shares: [   ]

(subject to adjustment)
	 	 	 
	Warrant No.	 	Original Issue Date: [   ]


 


Mersana Therapeutics, Inc., a Delaware corporation
(the “Company”), hereby certifies that, for good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, [ ] or its permitted registered assigns (the “Holder”), is entitled, subject
to the terms set forth below, to purchase from the Company up to a total of [ ] shares of common stock, $0.0001 par value per share
(the “ Common Stock”), of the Company (each such share, a “Warrant Share” and all such shares,
the “Warrant Shares”) at an exercise price per share equal to $0.0001 per share (as adjusted from time to time
as provided in Section 9 herein, the “Exercise Price”), upon surrender of this Warrant to Purchase Common
Stock (including any Warrants to Purchase Common Stock issued in exchange, transfer or replacement hereof, the “Warrant”)
at any time and from time to time on or after the date hereof (the “Original Issue Date”) and through and including
4:00 P.M., New York City time, on the date that is 10 years following the Original Issue Date (the “Expiration Date”),
and subject to the following terms and conditions:


 


		1.	Definitions. For purposes of this Warrant, the following terms shall have the following meanings:



 


		(a)	“Affiliate” means any Person directly or indirectly controlled by, controlling or under common control with,
a Holder, but only for so long as such control shall continue. For purposes of this definition, “control” (including,
with correlative meanings, “controlled by,” “controlling” and “under common control with”)
means, with respect to a Person, possession, direct or indirect, of (a) the power to direct or cause direction of the management
and policies of such Person (whether through ownership of securities or partnership or other ownership interests, by contract or
otherwise), or (b) at least 50% of the voting securities (whether directly or pursuant to any option, warrant or other similar
arrangement) or other comparable equity interests.



 


		(b)	“Commission” means the United States Securities and Exchange Commission.



 


		(c)	“Closing Sale Price” means, for any security as of any date, the last trade price for such security on the
Principal Trading Market for such security, as reported by Bloomberg Financial Markets, or, if such Principal Trading Market begins
to operate on an extended hours basis and does not designate the last trade price, then the last trade price of such security prior
to 4:00 P.M., New York City time, as reported by Bloomberg Financial Markets, or if the foregoing do not apply, the last trade
price of such security in the over-the-counter market on the electronic bulletin board for such security as reported by Bloomberg
Financial Markets, or, if no last trade price is reported for such security by Bloomberg Financial Markets, the average of the
bid and ask prices, of any market makers for such security as reported in the “pink sheets” by Pink Sheets LLC. If
the Closing Sale Price cannot be calculated for a security on a particular date on any of the foregoing bases, the Closing Sale
Price of such security on such date shall be the fair market value as mutually determined by the Company and the Holder. If the
Company and the Holder are unable to agree upon the fair market value of such security, then the Board of Directors of the Company
shall use its good faith judgment to determine the fair market value. The Board of Directors’ determination shall be binding
upon all parties absent demonstrable error. All such determinations shall be appropriately adjusted for any stock dividend, stock
split, stock combination or other similar transaction during the applicable calculation period.



 






    1


     


    

 


		(d)	“Principal Trading Market” means the national securities exchange or other trading market on which the Common
Stock is primarily listed on and quoted for trading, which, as of the Original Issue Date, shall be The Nasdaq Global Select Market.



 


		(e)	“Securities Act” means the Securities Act of 1933, as amended.



 


		(f)	“Trading Day” means any weekday on which the Principal Trading Market is open for trading.



 


		(g)	“Transfer Agent” means Computershare Trust Company, N.A., the Company’s transfer agent and registrar
for the Common Stock, and any successor appointed in such capacity.



 


		2.	Registration of Warrants. The Company shall register this Warrant, upon records to be maintained by the Company for
that purpose (the “Warrant Register”), in the name of the record Holder (which shall include the initial Holder or,
as the case may be, any registered assignee to which this Warrant is permissibly assigned hereunder) from time to time. The Company
may deem and treat the registered Holder of this Warrant as the absolute owner hereof for the purpose of any exercise hereof or
any distribution to the Holder, and for all other purposes, absent actual notice to the contrary.



 


		3.	Registration of Transfers. Subject to compliance with all applicable securities laws, the Company shall, or will cause
its Transfer Agent to, register the transfer of all or any portion of this Warrant in the Warrant Register, upon surrender of this
Warrant, and payment for all applicable transfer taxes (if any). Upon any such registration or transfer, a new warrant to purchase
Common Stock in substantially the form of this Warrant (any such new warrant, a “New Warrant”) evidencing the portion
of this Warrant so transferred shall be issued to the transferee, and a New Warrant evidencing the remaining portion of this Warrant
not so transferred, if any, shall be issued to the transferring Holder. The acceptance of the New Warrant by the transferee thereof
shall be deemed the acceptance by such transferee of all of the rights and obligations in respect of the New Warrant that the Holder
has in respect of this Warrant. The Company shall, or will cause its Transfer Agent to, prepare, issue and deliver at the Company’s
own expense any New Warrant under this Section 3. Until due presentment for registration of transfer, the Company may treat the
registered Holder hereof as the owner and holder of this Warrant for all purposes, and the Company shall not be affected by any
notice to the contrary.



 


		4.	Exercise and Duration of Warrants.



 


		(a)	All or any part of this Warrant shall be exercisable by the registered Holder in any manner permitted by Section 10
of this Warrant at any time and from time to time on or after the Original Issue Date and through and including 4:00 P.M. New York
City time, on the Expiration Date. At 4:00 P.M., New York City time, on the Expiration Date, the portion of this Warrant not exercised
prior thereto shall be and become void and of no value and this Warrant shall be terminated and no longer outstanding.



 


		(b)	The Holder may exercise this Warrant by delivering to the Company (i) an exercise notice, in the form attached as Schedule
1 hereto (the “Exercise Notice”), completed and duly signed, and (ii) payment of the Exercise Price for
the number of Warrant Shares as to which this Warrant is being exercised (which may take the form of a “cashless exercise”
if so indicated in the Exercise Notice pursuant to Section 10 below), and the date on which the last of such items is delivered
to the Company (as determined in accordance with the notice provisions hereof) is an “Exercise Date.” The Holder
shall not be required to deliver the original Warrant in order to effect an exercise hereunder. Execution and delivery of the Exercise
Notice shall have the same effect as cancellation of the original Warrant and issuance of a New Warrant evidencing the right to
purchase the remaining number of Warrant Shares.



 






    2


     


    

 


		5.	Delivery of Warrant Shares.



 


		(a)	Upon exercise of this Warrant, the Company shall promptly (but in no event more than five (5) Trading Days after the Exercise
Date), upon the request of the Holder, credit such aggregate number of shares of Common Stock to which the Holder is entitled pursuant
to such exercise to the Holder’s or its designee’s balance account with The Depository Trust Company (“DTC”)
through its Deposit Withdrawal Agent Commission system, or if the Transfer Agent is not participating in the Fast Automated Securities
Transfer Program (the “FAST Program”) or if the certificates or book entry position are required to bear a legend
regarding restriction on transferability, issue and dispatch by overnight courier to the address as specified in the Exercise Notice,
a certificate or book entry position, registered in the Company’s share register in the name of the Holder or its designee,
for the number of shares of Common Stock to which the Holder is entitled pursuant to such exercise. The Holder, or any natural
person or legal entity (each, a “Person”) permissibly so designated by the Holder to receive Warrant Shares,
shall be deemed to have become the holder of record of such Warrant Shares as of the Exercise Date, irrespective of the date such
Warrant Shares are credited to the Holder’s DTC account or the date of delivery of the certificates or book entry position
evidencing such Warrant Shares, as the case may be.



 


		(b)	If by the close of the fifth Trading Day after the Exercise Date, the Company fails to credit the Holder’s balance account
with DTC for such number of Warrant Shares to which the Holder is entitled, and if after such fifth Trading Day and prior to the
receipt of such Warrant Shares, the Holder purchases (in an open market transaction) shares of Common Stock to deliver in satisfaction
of a sale by the Holder of the Warrant Shares which the Holder anticipated receiving upon such exercise (a “Buy-In”),
then the Company shall, within two Trading Days after the Holder’s request and in its sole discretion, either (1) pay in
cash to the Holder an amount equal to the Holder’s total purchase price (including brokerage commissions, if any) for the
shares of Common Stock so purchased (the “Buy-In Price”), at which point the Company’s obligation to deliver
such Warrant Shares shall terminate or (2) promptly honor its obligation to deliver to the Holder the Warrant Shares and pay cash
to the Holder in an amount equal to the excess (if any) of Holder’s total purchase price (including brokerage commissions,
if any) for the shares of Common Stock so purchased in the Buy-In over the product of (A) the number of shares of Common Stock
purchased in the Buy-In, times (B) the average of the Closing Sale Prices of the shares of Common Stock (as reported by Bloomberg
Financial Markets) for the five (5) consecutive Trading Days ending on the date immediately preceding the Exercise Date. The provisions
of this Section 5(b) shall be the only remedy available to the Holder in the event the Company fails to deliver to the Holder the
required number of Warrant Shares in the manner required pursuant to Section 5(a) and a Buy-In occurs. Irrespective of whether
there is a Buy-In, no remedy shall be available, notwithstanding the requirements of Section 5(a), unless and until the Company
fails to deliver to the Holder the required number of Warrant Shares by the close of the fifth Trading Day after the Exercise Date.



 


		(c)	Subject to Section 5(b), nothing herein shall limit the Holder’s right to pursue any other remedies available
to it hereunder, at law or in equity including, without limitation, a decree of specific performance and/or injunctive relief with
respect to the Company’s failure to timely deliver certificates or a book entry position representing shares of Common Stock
upon exercise of the Warrant as required pursuant to the terms hereof.



 


		6.	Charges, Taxes and Expenses. Issuance and delivery of a book entry position for shares of Common Stock upon exercise
of this Warrant shall be made without charge to the Holder for any issue or transfer tax, transfer agent fee or other incidental
tax or expense (excluding any applicable stamp duties) in respect of the issuance of such certificates or book entry shares, all
of which taxes and expenses shall be paid by the Company; provided, however, that the Company shall not be required to pay
any tax that may be payable in respect of any transfer involved in the registration of any certificates for Warrant Shares or the Warrants in a name other than that of the Holder
or an Affiliate thereof. The Holder shall be responsible for all other tax liability that may arise as a result of holding or transferring
this Warrant or receiving Warrant Shares upon exercise hereof.



 








    3


     


    

 


		7.	Replacement of Warrant. If this Warrant is mutilated, lost, stolen or destroyed, the Company shall issue or cause to
be issued in exchange and substitution for and upon cancellation hereof, or in lieu of and substitution for this Warrant, a New
Warrant, but only upon receipt of evidence reasonably satisfactory to the Company of such loss, theft or destruction (in such case)
and, in each case, a customary and reasonable indemnity and surety bond, if requested by the Company. Applicants for a New Warrant
under such circumstances shall also comply with such other reasonable regulations and procedures and pay such other reasonable
third-party costs as the Company may prescribe. If a New Warrant is requested as a result of a mutilation of this Warrant, then
the Holder shall deliver such mutilated Warrant to the Company as a condition precedent to the Company’s obligation to issue
the New Warrant.



 


		8.	Reservation of Warrant Shares. The Company covenants that it will at all times while this Warrant is outstanding reserve
and keep available out of the aggregate of its authorized but unissued and otherwise unreserved Common Stock, solely for the purpose
of enabling it to issue Warrant Shares upon exercise of this Warrant as herein provided, the number of Warrant Shares that are
then issuable and deliverable upon the exercise of this Warrant, free from preemptive rights or any other contingent purchase rights
of persons other than the Holder (taking into account the adjustments and restrictions of Section 9). The Company covenants
that all Warrant Shares so issuable and deliverable shall, upon issuance and the payment of the applicable Exercise Price in accordance
with the terms hereof, be duly and validly authorized, issued and fully paid and nonassessable. The Company will take all such
action as may be reasonably necessary to assure that such shares of Common Stock may be issued as provided herein without violation
of any applicable law or regulation, or of any requirements of any securities exchange or automated quotation system upon which
the Common Stock may be listed.



 


		9.	Certain Adjustments. The number of Warrant Shares issuable upon exercise of this Warrant is subject to adjustment from
time to time as set forth in this Section 9.



 


		(a)	Stock Dividends and Splits. If the Company, at any time while this Warrant is outstanding, (i) pays a stock dividend
on its Common Stock or otherwise makes a distribution on any class of capital stock issued and outstanding on the Original Issue
Date and in accordance with the terms of such stock on the Original Issue Date or as amended, that is payable in shares of Common
Stock, (ii) subdivides its outstanding shares of Common Stock into a larger number of shares of Common Stock, (iii) combines its
outstanding shares of Common Stock into a smaller number of shares of Common Stock or (iv) issues by reclassification of shares
of capital stock any additional shares of Common Stock of the Company, then in each such case the number of Warrant Shares then
underlying this Warrant shall be divided by a fraction, the numerator of which shall be the number of shares of Common Stock outstanding
immediately before such event and the denominator of which shall be the number of shares of Common Stock outstanding immediately
after such event. Any adjustment made pursuant to clause (i) of this paragraph shall become effective immediately after the record
date for the determination of stockholders entitled to receive such dividend or distribution, provided, however, that if such record
date shall have been fixed and such dividend is not fully paid on the date fixed therefor, the number of Warrant Shares shall be
recomputed accordingly as of the close of business on such record date and thereafter the Warrant Shares shall be adjusted pursuant
to this paragraph as of the time of actual payment of such dividends. Any adjustment pursuant to clause (ii) or (iii) of this paragraph
shall become effective immediately after the effective date of such subdivision or combination.



 


		(b)	Pro Rata Distributions. If the Company, at any time while this Warrant is outstanding, distributes to all holders of
Common Stock for no consideration (i) evidences of its indebtedness, (ii) any security (other than a distribution of Common Stock
covered by the preceding paragraph), (iii) rights or warrants to subscribe for or purchase any security, or (iv) cash or any other
asset (in each case, “Distributed
Property”), then, upon any exercise of this Warrant that occurs after the record date fixed for determination of stockholders
entitled to receive such distribution, the Holder shall be entitled to receive, in addition to the Warrant Shares otherwise issuable
upon such exercise (if applicable), the Distributed Property that such Holder would have been entitled to receive in respect of
such number of Warrant Shares had the Holder been the record holder of such Warrant Shares immediately prior to such record date
without regard to any limitation on exercise contained therein.



 









    4


     


    

 


		(c)	Fundamental Transactions. If, at any time while this Warrant is outstanding (i) the Company effects any merger or consolidation
of the Company with or into another Person, in which the Company is not the surviving entity or the stockholders of the Company
immediately prior to such merger or consolidation do not own, directly or indirectly, at least 50% of the voting power of the surviving
entity immediately after such merger or consolidation, (ii) the Company effects any sale to another Person of all or substantially
all of its assets in one transaction or a series of related transactions, (iii) pursuant to any tender offer or exchange offer
(whether by the Company or another Person), holders of capital stock who tender shares representing more than 50% of the voting
power of the capital stock of the Company and the Company or such other Person, as applicable, accepts such tender for payment,
(iv) the Company consummates a stock purchase agreement or other business combination (including, without limitation, a reorganization,
recapitalization, spin-off or scheme of arrangement) with another Person whereby such other Person acquires more than the 50% of
the voting power of the capital stock of the Company (except for any such transaction in which the stockholders of the Company
immediately prior to such transaction maintain, in substantially the same proportions, the voting power of such Person immediately
after the transaction) or (v) the Company effects any reclassification of the Common Stock or any compulsory share exchange pursuant
to which the Common Stock is effectively converted into or exchanged for other securities, cash or property (other than as a result
of a subdivision or combination of shares of Common Stock covered by Section 9(a) above) (in any such case, a “Fundamental
Transaction”), then following such Fundamental Transaction the Holder shall have the right to receive, upon exercise
of this Warrant, the same amount and kind of securities, cash or property as it would have been entitled to receive upon the occurrence
of such Fundamental Transaction if it had been, immediately prior to such Fundamental Transaction, the holder of the number of
Warrant Shares then issuable upon exercise in full of this Warrant without regard to any limitations on exercise contained herein
(the “Alternate Consideration”). The Company shall not effect any Fundamental Transaction in which the Company
is not the surviving entity or the Alternate Consideration includes securities of another Person unless (i) the Alternate Consideration
is solely cash and the Company provides for the simultaneous “cashless exercise” of this Warrant pursuant to Section
10 below or (ii) prior to or simultaneously with the consummation thereof, any successor to the Company, surviving entity or
other Person (including any purchaser of assets of the Company) shall assume the obligation to deliver to the Holder, such Alternate
Consideration as, in accordance with the foregoing provisions, the Holder may be entitled to receive, and the other obligations
under this Warrant. The provisions of this paragraph (c) shall similarly apply to subsequent transactions analogous of a Fundamental
Transaction type.



 


		(d)	Calculations. All calculations under this Section 9 shall be made to the nearest share.



 


		(e)	Notice of Adjustments. Upon the occurrence of each adjustment pursuant to this Section 9, the Company at its
expense will, at the written request of the Holder, promptly compute such adjustment, in good faith, in accordance with the terms
of this Warrant and prepare a certificate setting forth such adjustment, including a statement of the adjusted number or type of
Warrant Shares or other securities issuable upon exercise of this Warrant (as applicable), describing the transactions giving rise
to such adjustments and showing in detail the facts upon which such adjustment is based. Upon written request, the Company will
promptly deliver a copy of each such certificate to the Holder and to the Company’s transfer agent.



 






    5


     


    

 


		(f)	Notice of Corporate Events. If, while this Warrant is outstanding, the Company (i) declares a dividend or any other
distribution of cash, securities or other property in respect of its Common Stock, including, without limitation, any granting
of rights or warrants to subscribe for or purchase any capital stock of the Company or any subsidiary, (ii) enters into any material
definitive agreement contemplating or soliciting stockholder approval for any Fundamental Transaction or (iii) authorizes the voluntary
dissolution, liquidation or winding up of the affairs of the Company, then, except if such notice and the contents thereof shall
be deemed to constitute material non-public information, the Company shall deliver to the Holder a notice of such transaction at
least ten (10) days prior to the applicable record or effective date on which a Person would need to hold Common Stock in order
to participate in or vote with respect to such transaction; provided, however, that the failure to deliver such notice or
any defect therein shall not affect the validity of the corporate action required to be described in such notice. Holder agrees
to maintain any information disclosed pursuant to this Section 9(f) in confidence until such information is publicly available
and shall comply with applicable law with respect to trading in the Company’s securities following receipt any such information.



 


		10.	Payment of Exercise Price. Notwithstanding anything contained herein to the contrary, the Holder may, in its sole discretion,
satisfy its obligation to pay the Exercise Price through a “cashless exercise,” in which event the Company shall issue
to the Holder the number of Warrant Shares determined as follows:



 


X = Y [(A-B)/A]


 


where:


 


“X” equals the number of Warrant
Shares to be issued to the Holder;


 


“Y” equals the total number
of Warrant Shares with respect to which this Warrant is then being exercised;


 


“A” equals the average of the
Closing Sale Prices of the shares of Common Stock (as reported by Bloomberg Financial Markets) for the five (5) consecutive Trading
Days ending on the date immediately preceding the Exercise Date; and


 


“B” equals the Exercise Price
then in effect for the applicable Warrant Shares at the time of such exercise.


 


Except as set forth in Section 12 (payment
of cash in lieu of fractional shares), in no event will the exercise of this Warrant be settled in cash.


 






    6


     


    

 


		11.	Limitations on Exercise.



 


		(a)	Notwithstanding anything to the contrary contained in any Section herein, except for Section 15, the number of
                                                                 Warrant Shares that may be acquired by the Holder upon any exercise of this Warrant (or otherwise in respect hereof) shall be
                                                                 limited to the extent necessary to ensure that, following such exercise (or other issuance), the total number of shares of
                                                                 Common Stock then beneficially owned by the Holder and its Affiliates and any other Persons whose beneficial ownership of
                                                                 Common Stock would be aggregated with the Holder’s for purposes of Section 13(d) of the Exchange Act, does not exceed
                                                                 9.99% of the total number of then issued and outstanding shares of Common Stock (including for such purpose the shares of
                                                                 Common Stock issuable upon such exercise), it being acknowledged by the Holder that the Company is not representing to such
                                                                 Holder that such calculation is in compliance with Section 13(d) of the Exchange Act and the rules and regulations
                                                                 promulgated thereunder and such Holder is solely responsible for any schedules required to be filed in accordance therewith.
                                                                 To the extent that the limitation contained in this Section 11(a) applies, the determination of whether this Warrant is
                                                                 exercisable (in relation to other securities owned by such Holder) and of which a portion of this Warrant is exercisable
                                                                 shall be in the sole discretion of the Holder, and the submission of a Notice of Exercise shall be deemed to be the Holder’s
determination of whether this Warrant is exercisable (in relation to other securities owned by such Holder) and of which portion
of this Warrant is exercisable, in each case subject to such aggregate percentage limitation, and the Company shall have no obligation
to verify or confirm the accuracy of such determination. In addition, a determination under this Section 11(a) as to any group
status shall be determined by the Holder in accordance with Section 13(d) of the Exchange Act and the rules and regulations promulgated
thereunder. For purposes of this Section 11(a), in determining the number of outstanding shares of Common Stock, the Holder may
rely on the number of outstanding shares of Common Stock as reflected in (x) the Company’s most recent Form 10-Q or Form
10-K, as the case may be, (y) a more recent public announcement by the Company or (z) any other notice by the Company or the Transfer
Agent setting forth the number of shares of Common Stock outstanding. Upon the written request of the Holder, the Company shall,
within three (3) Trading Days, confirm orally and in writing to such Holder the number of shares of Common Stock then outstanding.
By written notice to the Company, which will not be effective until the sixty-first (61st) day after such notice is delivered to
the Company, the Holder may waive the provisions of this Section 11(a) or increase the beneficial ownership limitation to such
percentage of the number of shares of the Common Stock outstanding immediately after giving effect to the issuance of shares of
Common Stock upon exercise of this Warrant as the Holder shall determine, in its sole discretion, subject to Section 11(b), and
the provisions of this Section 11(a) shall continue to apply. Upon such a change by a Holder of the beneficial ownership limitation
from such 9.99% limitation to such other percentage limitation, the beneficial ownership limitation may not be further waived or
increased by such Holder without first providing the minimum notice required by this Section 11(a). Notwithstanding the foregoing,
at any time following notice of a Fundamental Transaction under Section 9(f)(ii) with respect to a Section 9(c)(iii) Fundamental
Transaction, the Holder may waive and/or change the beneficial ownership limitation effective immediately upon written notice to
the Company and may reinstitute a beneficial ownership limitation at any time thereafter effective immediately upon written notice
to the Company.






 


		(b)	Notwithstanding anything to the contrary contained in any Section herein, except Section 15 (but including Section
11(a)), the Company shall not effect any exercise of this Warrant, and the Holder shall not be entitled to exercise this Warrant
for a number of Warrant Shares in excess of that number of Warrant Shares which, upon giving effect to such exercise, would cause
(i) the aggregate number of shares of Common Stock beneficially owned by the Holder and its Affiliates and any other Persons whose
beneficial ownership of Common Stock would be aggregated with the Holder’s for purposes of Section 13(d) of the Exchange
Act, to exceed 19.99% of the total number of issued and outstanding shares of Common Stock of the Company following such exercise,
or (ii) the combined voting power of the securities of the Company beneficially owned by the Holder and its Affiliates and any
other Persons whose beneficial ownership of Common Stock would be aggregated with the Holder’s for purposes of Section 13(d)
of the Exchange Act to exceed 19.99% of the combined voting power of all of the securities of the Company then outstanding following
such exercise. For purposes of this Section 11(b), the aggregate number of shares of Common Stock or voting securities beneficially
owned by the Holder and its Affiliates and any other Persons whose beneficial ownership of Common Stock would be aggregated with
the Holder’s for purposes of Section 13(d) of the Exchange Act shall include the shares of Common Stock issuable upon the
exercise of this Warrant with respect to which such determination is being made, but shall exclude the number of shares of Common
Stock which would be issuable upon (x) exercise of the remaining unexercised and non-cancelled portion of this Warrant by the Holder
and (y) exercise or conversion of the unexercised, non-converted or non-cancelled portion of any other securities of the Company
that do not have voting power (including without limitation any securities of the Company which would entitle the holder thereof
to acquire at any time Common Stock, including without limitation any debt, preferred stock, right, option, warrant or other instrument
that is at any time convertible into or exercisable or exchangeable for, or otherwise entitles the holder thereof to receive, Common
Stock), is subject to a limitation on conversion or exercise analogous
to the limitation contained herein and is beneficially owned by the Holder or any of its Affiliates and other Persons whose beneficial
ownership of Common Stock would be aggregated with the Holder’s
for purposes of Section 13(d) of the Exchange Act.



 






    7


     


    

 


		(c)	This Section 11 shall not restrict the number of shares of Common Stock which a Holder may receive or beneficially own
in order to determine the amount of securities or other consideration that such Holder may receive in the event of a Fundamental
Transaction as contemplated in Section 9 of this Warrant.



 


		12.	No Fractional Shares. No fractional Warrant Shares will be issued in connection with any exercise of this Warrant. In
lieu of any fractional shares that would otherwise be issuable, the number of Warrant Shares to be issued shall be rounded down
to the next whole number and the Company shall pay the Holder in cash the fair market value (based on the Closing Sale Price) for
any such fractional shares.



 


		13.	Notices. Any and all notices or other communications or deliveries hereunder (including, without limitation, any Exercise
Notice) shall be in writing and shall be deemed given and effective on the earliest of (i) the date of transmission, if such notice
or communication is delivered via confirmed e-mail at the e-mail address specified below prior to 4:00 P.M., New York City time,
on a Trading Day, (ii) the next Trading Day after the date of transmission, if such notice or communication is delivered via confirmed
e-mail at the e-mail address specified below on a day that is not a Trading Day or later than 4:00 P.M., New York City time, on
any Trading Day, (iii) the second Trading Day following the date of mailing, if sent by nationally recognized overnight courier
service specifying next business day delivery, or (iv) upon actual receipt by the Person to whom such notice is required to be
given, if by hand delivery. The e-mail address for purposes of providing notice hereunder is: legal@mersana.com.



 


		14.	Warrant Agent. The Company shall initially serve as warrant agent under this Warrant. Upon ten (10) days’ notice
to the Holder, the Company may appoint a new warrant agent. Any corporation into which the Company or any new warrant agent may
be merged or any corporation resulting from any consolidation to which the Company or any new warrant agent shall be a party or
any corporation to which the Company or any new warrant agent transfers substantially all of its corporate trust or shareholders
services business shall be a successor warrant agent under this Warrant without any further act. Any such successor warrant agent
shall promptly cause notice of its succession as warrant agent to be mailed (by first class mail, postage prepaid) to the Holder
at the Holder’s last address as shown on the Warrant Register.



 


		15.	Automatic Exercise on the Expiration Date. In the event that, upon the Expiration Date, the Closing Sale Price on the
Trading Day immediately preceding the Expiration Date (as determined in accordance with this Warrant) is greater than the Exercise
Price in effect on such date, then this Warrant shall automatically be deemed on and as of such date to be exercised pursuant to
a “cashless exercise” to the extent permitted under Section 10 of this Warrant as to all Warrant Shares for
which this Warrant shall not previously have been exercised or converted, without regard to the limitations on exercise set forth
in Section 11, and the Company shall promptly deliver a certificate representing such shares issued upon such exercise to
the Holder.



 


		16.	Miscellaneous.



 


		(a)	No Rights as a Stockholder. The Holder, solely in such Person’s capacity as a holder of this Warrant, shall not
be entitled to vote or receive dividends or be deemed the holder of share capital of the Company for any purpose, nor shall anything
contained in this Warrant be construed to confer upon the Holder, solely in such Person’s capacity as the Holder of this
Warrant, any of the rights of a stockholder of the Company or any right to vote, give or withhold consent to any corporate action
(whether any reorganization, issue of stock, reclassification of stock, consolidation, merger, amalgamation, conveyance or otherwise),
receive notice of meetings, receive dividends or subscription rights, or otherwise,
prior to the issuance to the Holder of the Warrant Shares which such Person is then entitled to receive upon the due exercise of
this Warrant. In addition, nothing contained in this Warrant shall be construed as imposing any liabilities on the Holder to purchase
any securities (upon exercise of this Warrant or otherwise) or as a stockholder of the Company, whether such liabilities are asserted
by the Company or by creditors of the Company.



 









    8


     


    

 


		(b)	Authorized Shares. Except and to the extent as waived or consented to by the Holder, the Company shall not amend its
certificate or articles of incorporation or effect any reorganization, transfer of assets, consolidation, merger, dissolution,
issue or sale of securities or any other voluntary action to avoid or seek to avoid the observance or performance of any of the
terms of this Warrant, but will at all times in good faith assist in the carrying out of all such terms and in the taking of all
such actions as may be necessary or appropriate to protect the rights of Holder as set forth in this Warrant against impairment.
Without limiting the generality of the foregoing, the Company will (a) not increase the par value of any Warrant Shares above the
amount payable therefor upon such exercise immediately prior to such increase in par value, (b) take all such action as may be
necessary or appropriate in order that the Company may validly and legally issue fully paid and nonassessable Warrant Shares upon
the exercise of this Warrant, and (c) use commercially reasonable efforts to obtain all such authorizations, exemptions or consents
from any public regulatory body having jurisdiction thereof as may be necessary to enable the Company to perform its obligations
under this Warrant.



 


		(c)	Successors and Assigns. Subject to the restrictions on transfer set forth in this Warrant and compliance with applicable
securities laws, this Warrant may be assigned by the Holder. This Warrant may not be assigned by the Company without the written
consent of the Holder except to a successor in the event of a Fundamental Transaction. This Warrant shall be binding on and inure
to the benefit of the Company and the Holder and their respective successors and assigns. Subject to the preceding sentence, nothing
in this Warrant shall be construed to give to any Person other than the Company and the Holder any legal or equitable right, remedy
or cause of action under this Warrant. This Warrant may be amended only in writing signed by the Company and the Holder, or their
successors and assigns.



 


		(d)	Amendment and Waiver. Except as otherwise provided herein, the provisions of the Warrants may be amended and the Company
may take any action herein prohibited, or omit to perform any act herein required to be performed by it, only if the Company has
obtained the written consent of the Holders of Warrants representing no less than a majority of the Warrant Shares obtainable upon
exercise of the Warrants then outstanding.



 


		(e)	Acceptance. Receipt of this Warrant by the Holder shall constitute acceptance of and agreement to all of the terms and
conditions contained herein.



 


		(f)	Governing Law; Jurisdiction. ALL QUESTIONS CONCERNING THE CONSTRUCTION, VALIDITY, ENFORCEMENT AND INTERPRETATION OF
THIS WARRANT SHALL BE GOVERNED BY AND CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD
TO THE PRINCIPLES OF CONFLICTS OF LAW THEREOF. EACH OF THE COMPANY AND THE HOLDER HEREBY IRREVOCABLY SUBMITS TO THE EXCLUSIVE JURISDICTION
OF THE STATE AND FEDERAL COURTS SITTING IN THE CITY OF NEW YORK, BOROUGH OF MANHATTAN, FOR THE ADJUDICATION OF ANY DISPUTE HEREUNDER
OR IN CONNECTION HEREWITH OR WITH ANY TRANSACTION CONTEMPLATED HEREBY OR DISCUSSED HEREIN (INCLUDING WITH RESPECT TO THE ENFORCEMENT
OF ANY OF THE TRANSACTION DOCUMENTS), AND HEREBY IRREVOCABLY WAIVES, AND AGREES NOT TO ASSERT IN ANY SUIT, ACTION OR PROCEEDING,
ANY CLAIM THAT IT IS NOT PERSONALLY SUBJECT TO THE JURISDICTION OF ANY SUCH COURT. EACH OF THE COMPANY AND THE HOLDER HEREBY IRREVOCABLY
WAIVES PERSONAL SERVICE OF PROCESS AND CONSENTS TO PROCESS BEING SERVED IN ANY SUCH SUIT, ACTION OR PROCEEDING BY MAILING A COPY
THEREOF VIA REGISTERED OR CERTIFIED MAIL OR OVERNIGHT DELIVERY (WITH EVIDENCE OF DELIVERY) TO SUCH PERSON AT THE ADDRESS IN EFFECT
FOR NOTICES TO IT AND AGREES THAT SUCH SERVICE SHALL CONSTITUTE GOOD AND SUFFICIENT SERVICE OF PROCESS AND NOTICE THEREOF. NOTHING
CONTAINED HEREIN SHALL BE DEEMED TO LIMIT IN ANY WAY ANY RIGHT TO SERVE PROCESS IN ANY MANNER PERMITTED BY LAW. EACH OF THE COMPANY
AND THE HOLDER HEREBY WAIVES ALL RIGHTS TO A TRIAL BY JURY.



 









    9


     


    

 


		(g)	Headings. The headings herein are for convenience only, do not constitute a part of this Warrant and shall not be deemed
to limit or affect any of the provisions hereof.



 


		(h)	Severability. In case any one or more of the provisions of this Warrant shall be invalid or unenforceable in any respect,
the validity and enforceability of the remaining terms and provisions of this Warrant shall not in any way be affected or impaired
thereby, and the Company and the Holder will attempt in good faith to agree upon a valid and enforceable provision which shall
be a commercially reasonable substitute therefor, and upon so agreeing, shall incorporate such substitute provision in this Warrant.



 


[REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]


 






    10


     


    

 


IN WITNESS WHEREOF, the Company has caused
this Warrant to be duly executed by its authorized officer as of the date first indicated above.


 


	 	MERSANA THERAPEUTICS, INC.
	 	 
	 	 
	 	By:	 
	 	Name:	                  
	 	Title:	 


 






     


     


    

 


SCHEDULE 1


 


FORM OF EXERCISE NOTICE


 


[To be executed by the Holder to purchase
shares of Common Stock under the Warrant]


 


Ladies and Gentlemen:


 


	(1)	The undersigned is the Holder of Warrant No.          (the “Warrant”) issued by Mersana Therapeutics, Inc., a Delaware corporation (the “Company”). Capitalized terms used herein and not otherwise defined herein have the respective meanings set forth in the Warrant.
	 	 
	(2)	The undersigned hereby exercises its right to purchase Warrant Shares pursuant to the Warrant.
	 	 
	(3)	The Holder intends that payment of the Exercise Price shall be made as (check one):
	 	 
	 	 ̈	Cash Exercise 
	 	 	 
	 	 ̈	“Cashless Exercise” under Section 10 of the Warrant 
	 	 
	(4)	If the Holder has elected a Cash Exercise, the Holder shall pay the sum of $           in immediately available funds to the Company in accordance with the terms of the Warrant.
	 	 
	(5)	Pursuant to this Exercise Notice, the Company shall deliver to the Holder Warrant Shares determined in accordance with the terms of the Warrant.
	 	 
	(6)	By its delivery of this Exercise Notice, the undersigned represents and warrants to the Company that in giving effect to the exercise evidenced hereby the Holder will not beneficially own in excess of the number of shares of Common Stock (as determined in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended) permitted to be owned under Section 11(a) or Section 11(b), as applicable, of the Warrant to which this notice relates.



 


	Dated:	 	 
	 	 	 
	Name of Holder:	 	 
	 	 	 
	By:	 	 
	 	 	 
	Name:	 	 
	 	 	 
	Title:	 	 


(Signature must conform in all respects
to name of Holder as specified on the face of the Warrant)