Document:

EX-10.9

 Exhibit 10.9 

EMPLOYMENT AGREEMENT 

This Employment Agreement (this “Agreement”), dated as of February 24, 2015, is entered into by and between Merrimack
Pharmaceuticals, Inc., a Delaware corporation with a place of business at One Kendall Square, Suite B7201, Cambridge, Massachusetts 02139 (the “Company”), and Birgit M. Schoeberl, an individual residing at 183 Clark Street,
Cambridge, MA 02139 (the “Employee”). 
 RECITALS 

WHEREAS, the Company desires to continue to employ the Employee as Head of Discovery; and 

WHEREAS, the Employee desires to continue such employment upon the terms and conditions set forth in this Agreement. 

NOW, THEREFORE, in consideration of the foregoing and of the respective covenants and agreements of the parties herein contained, the parties
hereto agree as follows: 
 1. Term of Employment. Subject to the terms and conditions hereinafter set forth,
the Company hereby employs the Employee, and the Employee hereby enters into the employment of the Company, for an employment term commencing on the date set forth above and, unless earlier terminated in accordance with the provisions set forth in
Section 10, continuing until December 31, 2015. This Agreement shall renew automatically for successive one (1) year terms, unless either party shall give the other notice of non-renewal in accordance with Section 10. Both the
initial term of this Agreement and any annual renewal term of this Agreement shall be referred to as the “Term of Employment.” The Employee’s Base Salary (as defined below) for any renewal term shall be as agreed by the
parties, provided that (i) the Base Salary shall in no event be less than the Base Salary the Employee received in the immediately preceding term, and (ii) in the absence of an agreement otherwise, the Employee’s Base Salary shall be
the same as the Base Salary she received in the immediately preceding term. 
 2. Position. During the Term of
Employment, the Employee shall serve as Head of Discovery of the Company and in such additional position(s) as she and the Company shall agree. 

3. Scope of Employment. During the Term of Employment, the Employee shall be responsible for the performance of
all financial, managerial and administrative duties customarily performed by a Head of Discovery, together with such other duties as the Chief Executive Officer and the Employee shall agree. The Employee shall be accountable to the Chief Executive
Officer and shall perform and discharge, faithfully, diligently and to the best of her ability, her duties and responsibilities hereunder. The Employee shall devote substantially all of her working time and efforts to the business and affairs of the
Company and its affiliates. 

 4. Compensation. As full compensation for all services to be rendered
by the Employee during the Term of Employment, the Company will provide to the Employee, and the Employee will accept, the following: 
 (a)
Base Salary. During the Term of Employment, the Employee shall receive a salary of $268,661 per calendar year, less all applicable taxes and withholdings (the “Base Salary”), paid in installments in accordance with the
Company’s regularly established payroll procedure. The Employee’s Base Salary shall be reviewed annually by the Company’s Board of Directors (the “Board”) and may be adjusted from time to time in accordance with
normal business practices and taking into account then-current market factors, but in no event shall the Employee’s salary be less than the base salary the Employee received from the Company in the immediately preceding year. 

(b) Bonus. During the Term of Employment, the Employee shall be eligible to receive a discretionary annual performance and retention
bonus of up to 35% of her then current Base Salary, at a time and under circumstances determined by the Board, in its sole discretion. In order to receive the discretionary annual performance bonus, the Employee must be an active employee of the
Company on the date any bonus is determined and no discretionary annual bonus shall be considered earned before such date. Such discretionary bonus, if any, shall be paid no later than sixty (60) days following the date on which the Board
approves such bonus. 
 (c) Stock Options; Equity Grants. The Employee shall be eligible to receive option grants or other equity
grants at times and under circumstances determined by the Board, in its sole discretion. 
 (d) Vacation. The Employee shall be
eligible for vacation time in accordance with the Company’s Paid Time Off Policy contained within the Company’s Employee Handbook, as amended and/or superseded from time to time. 

(e) Insurance. The Employee shall be entitled to participate in, and receive benefits under, all Company sponsored insurance and
benefit programs (i.e. health, dental, life, and disability) available to senior management employees of the Company, subject to and on a basis consistent with the terms, conditions and overall administration of such programs. 

(f) Other Benefits. The Employee shall be entitled to participate in, and receive benefits under, all Company employee benefit plans
and arrangements (including but not limited to 401(k) and similar programs), available to senior management employees of the Company, subject to and on a basis consistent with the terms, conditions and overall administration of such plans, policies
and arrangements. 
 5. Expenses. The Employee shall be entitled to reimbursement by the Company for all
reasonable expenses actually incurred by him on the Company’s behalf in the course of her employment by the Company, upon the prompt presentation by the Employee, from time to time, of an itemized account of such expenditures together with all
supporting vouchers and receipts. All expense reimbursements shall be subject to the terms set forth in Section 5 of Exhibit C. 

6. Restrictive Covenants. 

(a) Non-Competition. The Employee agrees that, during the Term of Employment and any Severance Period (as defined below), and for a
period of one (1) year thereafter, she will not engage, directly or indirectly, in any business that competes with the business of the Company. For purposes of this paragraph, a business competes with the business

  
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of the Company if it is engaged in the research, development, production, sales or marketing of any diagnostic or therapeutics process or product that is directed at any molecular targets or
related to any therapeutic candidate compound that the Company developed, produced or sold, or planned to develop, produce or sell, while the Employee was employed with the Company. The Employee will be deemed to be directly or indirectly engaged in
a competitive business if she is engaged in such competitive business as proprietor, partner, joint venturer, stockholder (other than the holder of less than two percent (2%) of the outstanding shares of any publicly owned corporation),
director, officer, manager, member, employee, consultant, independent contractor, adviser, marketer, or agent or if she otherwise controls such business. 

(b) Non-Solicitation. The Employee agrees with the Company that during the Term of Employment and any Severance Period, and for a
period of one (1) year thereafter, she will not, directly or indirectly, solicit, entice away, employ, hire or otherwise interfere with the Company’s relationship with any officer, employee, consultant or agent of the Company. 

(c) Waiver. The Company may waive the prohibitions of Sections 6(a) or (b) hereof without waiving any other provisions of this
Agreement 
 (d) Validity. In the event any provision of Section 6(a) or 6(b) hereof shall to any extent be held to be invalid
or unenforceable by reason of geographic or business scope or the duration thereof, such invalidity or enforceability shall attach only to such provision to the extent of such invalidity, and shall not affect or render invalid or unenforceable any
other provision of this Agreement and, in such event, such provision shall be deemed to be modified to such extent as may be necessary to cause the geographic or business scope or duration thereof to be valid and enforceable to the maximum extent
permitted by law. 
 (e) Pre-existing Obligations. The Employee agrees that the restrictive covenants contained herein do not cancel
or modify the Employee’s obligations under the Non-Disclosure, Developments, Non-Competition and Non-Solicitation Agreement attached hereto as Exhibit A and executed on the date hereof, except to the extent set forth in Section 14.

 7. Confidential Information. While employed by the Company and thereafter, the Employee shall not, directly
or indirectly, use any Confidential Information (as hereinafter defined) other than pursuant to her employment by and for the benefit of the Company, or disclose any such Confidential Information to anyone outside of the Company whether by private
communication, public address, publication or otherwise or to anyone within the Company who has not been authorized to receive such information, except as directed in writing by the Board. For purposes of this Section 7, “Confidential
Information” means all trade secrets, proprietary information, and other data and information, in any form, belonging to the Company or any of its clients, customers, consultants, licensees or affiliates, that is held in confidence by the
Company. Confidential Information includes but is not limited to computer software, business plans and arrangements, customer lists, marketing materials, financial information, research, and any other information identified or treated as
confidential by the Company or any of its clients, customers, consultants, licensees or affiliates. Notwithstanding the foregoing, Confidential Information does not include information which the Company has voluntarily disclosed to the public
without restriction, or which is otherwise known to the public at large through no fault of the Employee. The Employee further acknowledges and reaffirms her 

  
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obligation to keep confidential and not to disclose any and all Confidential Information that she has acquired or will acquire during the course of her employment with the Company, as is stated
more fully in the Non-Disclosure, Developments, Non-Competition and Non-Solicitation Agreement attached hereto as Exhibit A and executed on the date hereof. 

8. Developments. As a condition of the Employee’s employment with the Company and the promises contained
herein, the Employee acknowledges and reaffirms her obligations, as stated more fully in the Non-Disclosure, Developments, Non-Competition and Non-Solicitation Agreement attached hereto as Exhibit A and executed on the date hereof, except to
the extent set forth in Section 14. 
 9. Injunctive Relief. The parties hereto recognize that irreparable
damage will result to the Company and its business and properties if the Employee fails or refuses to perform her obligations under Section 6(a), 6(b), 7 or 8 hereof, and that the remedy at law for any such failure or refusal will be
inadequate. Accordingly, in addition to any other remedies and damages available, the Company shall be entitled to injunctive relief, and the Employee may be specifically compelled to perform her obligations thereunder. 

10. Early Termination. 

(a) Death and Disability. In the event of the Employee’s death during the Term of Employment, this Agreement shall terminate
immediately. If, during the Term of Employment, the Employee shall be unable for a period of more than any three (3) consecutive months or for periods aggregating more than twenty-six (26) weeks in a twelve (12) month period to
perform the services provided for herein as a result of any illness or disability, the Company may terminate the Employee’s employment hereunder. The Employee shall be considered unable to perform the services provided for herein if and
whenever the Company reasonably determines, based upon the results of a medical examination performed by a mutually agreed-upon professional, that she is mentally or physically incapable of performing her duties hereunder. 

(b) Termination for Cause. The Employee may be terminated by the Company without notice for “Cause.” The following, as
determined by the Board in its reasonable judgment, shall constitute “Cause” for termination: 
 (i) Failure to Perform
Duties. The Employee’s material failure to perform (other than by reason of illness or disability) her duties to the Company, or her material negligence in the performance of her duties and/or responsibilities to the Company, provided that
the Employee shall have had prior written notice and a reasonable opportunity of not less than thirty (30) days to correct any deficiency in such performance; 

(ii) Breach of Employment Agreement. The Employee’s material breach of this Agreement; 

(iii) Misconduct. The Employee’s conviction for or plea of nolo contendere or guilty to any crime involving fraud,
embezzlement or moral turpitude; or 

  
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 (iv) Harmful Conduct. Any conduct of the Employee that is materially harmful to the
business, interests or reputation of the Company, provided that the Employee shall have had prior written notice and a reasonable opportunity of not less than ten (10) days to correct any such conduct. 

(c) Termination By Company Without Cause. The Employee may be terminated by the Company without “Cause” upon delivery of
written notice to the Employee. In the event the Employee is terminated without “Cause,” the Employee shall be entitled to receive the severance benefits set forth in Section 10(f) or 10(g), as applicable. The Company’s decision
not to renew the Term of Employment shall constitute a termination without “Cause.” 
 (d) Termination by the Employee for Good
Reason. This Agreement may be terminated by the Employee for “Good Reason” (as defined below), upon thirty (30) days’ prior written notice to the Company, provided that the Company shall have the opportunity to cure the
asserted Good Reason within the thirty (30) day period. The Employee shall have “Good Reason” to terminate this Agreement in the event that the Company, without the express written consent of the Employee: (i) causes a
material diminution of the Employee’s authority, duties or responsibilities; (ii) materially breaches this Agreement, including, without limitation, by materially reducing the Employee’s Base Salary or (iii) relocating the
Employee’s place of business by more than thirty (30) miles from the Company’s current Cambridge, Massachusetts office. In the event the Employee terminates her employment for Good Reason, the Employee shall be entitled to the
severance benefits set forth in Section 10(f) or 10(g), as applicable. 
 (e) Effect of Early Termination. Except for a
termination by the Company without “Cause” or by the Employee for “Good Reason,” in the event of any early termination of the Term of Employment, the Company’s obligations under this Agreement shall immediately cease and the
Employee shall be entitled to only the Employee’s Base Salary and employment benefits which have accrued and to which the Employee is entitled to through the date of such termination, including any bonus that may have been awarded but not yet
paid. These accrued salary and benefits shall be paid on or about the date of termination. The Employee shall not be entitled to any other compensation or consideration, including any bonus not yet awarded that the Employee may have been eligible
for had her Term of Employment not ceased, except as otherwise set forth in this Section 10(e). In the event of an early termination of the Term of Employment due to the Employee’s disability, as set forth in Section 10(a), the
Employee will be eligible to receive a pro rata amount of any bonus she would have received had her Term of Employment not ceased (determined in the manner set forth in the penultimate sentence of Section 10(f)), which bonus shall be paid
within thirty (30) days of the date of the Employee’s termination. 
 (f) Severance Benefits Prior to a Change in Control.
If the Term of Employment is terminated by the Company without “Cause” (as that term is defined in Section 10(b)) or by the Employee for “Good Reason” (as that term is defined in Section 10(d)), in each case prior
to a Change in Control (as that term is defined in Exhibit B), the Employee shall be entitled to receive her Base Salary and all other employment benefits accrued through the effective date of such termination, which shall be paid on or about
the date of termination. In addition, provided the Employee executes and allows to become binding a severance agreement and release of claims drafted by and satisfactory to the Company (the “Release”) on or before the

  
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sixtieth (60th) day after the date of termination, then beginning on the first regularly scheduled payroll that is sixty (60) days
following the date of termination (such date, the “Payment Commencement Date”), for a period of nine (9) months (or twelve (12) months if the Employee was employed by the Company for at least five (5) consecutive
years immediately prior to such date of termination) (the “Severance Period”), the Company shall: (i) pay to the Employee her base salary in accordance with the Company’s regularly established payroll procedure,
(ii) pay for coverage under any benefit plans provided pursuant to Section 4(e), provided the Employee is eligible for and elects to continue receiving such benefits pursuant to the federal “COBRA” law, 29 U.S.C. § 1161 et.
seq., and provided further that the Employee continues to pay the applicable share of the premium for such coverage that is paid for active and similarly situated employees who receive the same type of coverage, and (iii) to the extent allowed
by applicable law and the applicable plan documents, continue to provide the Employee with such benefits as described in Section 4(f), subject to and on a basis consistent with the terms, conditions and overall administration of such plans. In
addition, the Company shall pay to the Employee, on the Payment Commencement Date, a pro-rata bonus equal to (A) the average of the Employee’s annual bonus payments over each of the three (3) years prior to the year of termination
(or, if the Employee is an executive officer, such lesser period during which the Employee served as an executive officer of the Company) multiplied by (B) a fraction, the numerator of which is the number of days during the year during which
the Employee remained employed by the Company and the denominator of which is 365. The distribution of all severance benefits under this Section 10(f) shall be subject to the provisions of Exhibit C. 

(g) Severance Benefits After a Change in Control. If the Term of Employment is terminated by the Company without “Cause” (as
that term is defined in Section 10(b)) or by the Employee for “Good Reason” (as that term is defined in Section 10(d)), in each case within the eighteen (18) month period following a Change in Control (as that term is
defined in Exhibit B), the Employee shall be entitled to receive her Base Salary and all other employment benefits accrued through the effective date of such termination, which shall be paid on or about the date of termination. In addition,
provided the Employee executes and allows to become binding the Release on or before the Payment Commencement Date, the Company shall: (i) pay to the Employee on the Payment Commencement Date a lump sum amount equal to thirty-six
(36) months of her Base Salary; (ii) pay to the Employee on the Payment Commencement Date a bonus equal to (A) three (3) multiplied by (B) the average of the Employee’s annual bonus payments over each of the three
(3) years prior to the year of termination (or, if the Employee is an executive officer, such lesser period during which the Employee served as an executive officer of the Company); (iii) accelerate the vesting of all outstanding Company
stock options, restricted stock or other equity awards granted to the Employee; (iv) pay for coverage under any benefit plans provided pursuant to Section 4(e) for a period of eighteen (18) months following the Employee’s date of
termination, provided the Employee is eligible for and elects to continue receiving such benefits pursuant to the federal “COBRA” law, 29 U.S.C. § 1161 et. seq., and provided further that the Employee continues to pay the applicable
share of the premium for such coverage that is paid for active and similarly situated employees who receive the same type of coverage; and (v) to the extent allowed by applicable law and the applicable plan documents, continue for a period of
eighteen (18) months following the Employee’s date of termination to provide the Employee with such benefits as described in Section 4(f), subject to and on a basis consistent with the terms, conditions and overall administration of
such plans. The distribution of all severance benefits under this Section 10(g) shall be subject to the provisions of Exhibit C. 

  
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 11. Absence of Restrictions. The Employee represents and
warrants that she is not a party to any commitment or undertaking by which she is subject to any restriction or limitation upon her entering into this Agreement or performing the services required of him hereunder. 

12. Amendments. Any amendment to this Agreement, including any extension or renewal of the Term of
Employment, shall be made in writing and signed by the parties hereto. 
 13. Applicable Law. This
Agreement shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts (without reference to the conflict of laws provisions thereof). Any action, suit or other legal proceeding arising under or relating to any
provision of this Agreement shall be commenced only in a court of the Commonwealth of Massachusetts (or, if appropriate, a federal court located within the Commonwealth of Massachusetts), and the Company and the Employee each consents to the
jurisdiction of such a court. The Company and the Employee each hereby irrevocably waives any right to a trial by jury in any action, suit or other legal proceeding arising under or relating to any provision of this Agreement. 

14. Entire Agreement. This Agreement, together with the Non-Disclosure, Developments, Non-Competition and
Non-Solicitation Agreement attached hereto as Exhibit A and executed on the date hereof, constitutes the entire agreement between the parties and supersedes all prior agreements and understandings, whether written or oral, relating to the
subject matter of these agreements; provided however that the Employee and the Company agree that Section 4(a) of the Non-Disclosure, Developments, Non-Competition and Non-Solicitation Agreement is superseded by this Agreement. 

15. Successors and Assigns. This Agreement shall be binding upon and inure to the benefit of both parties
and their respective successors and assigns, including any corporation with which or into which the Company may be merged or which may succeed to its assets or business; provided, however, that the obligations of the Employee are personal and shall
not be assigned by him. 
 16.
Acknowledgment. The Employee states and represents that she has had an opportunity to fully discuss and review the terms of this Agreement with an attorney. The
Employee further states and represents that she has carefully read this Agreement, understands the contents herein, freely and voluntarily assents to all of the terms and conditions hereof, and signs her name of her own free act. 

17. Miscellaneous. 

(a) No delay or omission by the Company in exercising any right under this Agreement shall operate as a waiver of that or any other right. A
waiver or consent given by the Company on any one occasion shall be effective only in that instance and shall not be construed as a bar to or waiver of any right on any other occasion. 

(b) The captions of the sections of this Agreement are for convenience of reference only and in no way define, limit or affect the scope or
substance of any section of this Agreement. 

  
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 (c) In case any provision of this Agreement shall be invalid, illegal or otherwise unenforceable,
the validity, legality and enforceability of the remaining provisions shall in no way be affected or impaired thereby. 
 IN WITNESS
WHEREOF, the parties hereto have executed this Agreement as of the date first written above. 
  

							
	COMPANY:				MERRIMACK PHARMACEUTICALS, INC.
				
					By:		 /s/ Robert J. Mulroy

							Robert J. Mulroy
							President and Chief Executive Officer
			
	EMPLOYEE:				 /s/ Birgit M. Schoeberl

					Birgit M. Schoeberl

  
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 Exhibit A 

Non-Disclosure, Developments, Non-Competition and Non-Solicitation Agreement 

 NON-DISCLOSURE, DEVELOPMENTS, NON-COMPETITION 

AND NON-SOLICITATION AGREEMENT 

This Non-Disclosure, Developments, Non-Competition and Non-Solicitation Agreement (the “Agreement”), dated as of February 24,
2015, is entered into by and between Merrimack Pharmaceuticals, Inc., a Delaware corporation (the “Company”), and Birgit M. Schoeberl (the “Employee”). 

In consideration of the Employee’s employment with the Company and for other valuable consideration, the receipt and sufficiency of which
are hereby acknowledged by the Employee, the Employee hereby agrees as follows: 
 1. Condition of Employment. 

The Employee acknowledges that his/her employment and the continuance of that employment with the Company is contingent upon his/her agreement
to sign and adhere to the provisions of this Agreement. The Employee further acknowledges that the nature of the Company’s business is such that protection of its proprietary and confidential information is critical to its survival and success.

 2. Proprietary and Confidential Information. 

(a) The Employee agrees that all information and know-how, whether or not in writing, of a private, secret or confidential nature concerning
the Company and its operations and business or financial affairs (collectively, “Proprietary Information”) is and shall be the exclusive property of the Company. By way of illustration, but not limitation, Proprietary Information
may include models, systems, software and codes, or systems, software and codes in the course of development, or planned or proposed systems, software or codes, customer, prospect and supplier lists, contacts at or knowledge of customers or
prospective customers, customer accounts and other customer financial information, strategic partners and/or collaborators, price lists and all other pricing, marketing and sales information, projections, results relating to the Company or any
customer or supplier of the Company, databases, modules, products, programs, product improvements, product enhancements and/or developments, designs, specifications, processes, methods, techniques, operations, projects, plans, chemical compounds,
chemical or biological materials, engineering data, clinical or technological data, research data, financial data, personnel information, and other confidential agreements or documents (including, without limitation, clinical trial protocols and
unpublished patent applications). The Employee will not disclose any Proprietary Information to others outside the Company or use the same for any unauthorized purposes without written approval by an officer of the Company, either during or at any
time after his/her employment with the Company, unless and until such Proprietary Information has become public knowledge without fault by the Employee. While employed by the Company, the Employee will use the Employee’s best efforts to prevent
publication or disclosure of any confidential or Proprietary Information. 
 (b) The Employee agrees that all Company Property (as defined
below), whether created by the Employee or others, that shall come into the Employee’s custody or possession shall be and is the sole and exclusive property of the Company to be used only in the

 
performance of the Employee’s duties for the Company. “Company Property” means any and all written, photographic or any other record containing Proprietary Information and
shall include, but not be limited to, all agreements, notes, disks, files, letters, memoranda, reports, records, lists, data, drawings, sketches, notebooks, program listings, specifications, software programs, software code, computers and other
electronic equipment, documentation, or other equipment or materials of any nature and in any form, containing Proprietary Information. Upon the earliest of the Employee’s termination or a request from the Company, the Employee will return to
the Company any and all Company Property in the Employee’s custody or possession without retaining any copies thereof (including, without limitation, any electronic copy) and without using or allowing others to improperly use such Company
Property. 
 (c) The Employee acknowledges that the Employee’s obligations with regard to Proprietary Information that are set out in
Sections 2(a) and (b) extend to all information, know-how, records and tangible property of customers of the Company or suppliers to the Company or of any third party who may have disclosed or entrusted the same to the Company or to the
Employee in the course of the Company’s business. 
 3. Developments. 

(a) The Employee will make full and prompt disclosure to the Company of all inventions, ideas, concepts, improvements, discoveries, methods,
techniques, tools, formula, developments, enhancements, modifications, databases, processes, software and works of authorship, whether patentable or not, that are created, made, conceived or reduced to practice by the Employee or under the
Employee’s direction or jointly with others during the Employee’s employment by the Company, whether or not during normal working hours or on the premises of the Company (all of which are collectively referred to in this Agreement as
“Developments”). 
 (b) The Employee agrees to assign and does hereby assign to the Company (or any person or entity
designated by the Company) all of the Employee’s right, title and interest in and to all Developments and all related intellectual property rights. Except as, and solely to the extent that, it may be necessary for the Employee to
perform the Employee’s duties and fulfill the Employee’s obligations in the course of the Employee’s employment with the Company, the Company does not grant the Employee, and the Employee agrees that he/she will not receive,
any license or right to use any Development or related intellectual property right. The Employee hereby also waives all claims to moral rights in any Developments. However, this Section 3(b) shall not apply to Developments that do not relate to
the present or planned business or research and development of the Company and that are made and conceived by the Employee not during normal working hours, not on the Company’s premises and not using the Company’s tools, devices, equipment
or Proprietary Information. This Section 3(b) also shall not apply to any inventions that the Employee conceived of prior to the Employee’s employment with the Company, which invention(s) the Employee shall disclose on Exhibit A
attached hereto. IF THERE ARE ANY SUCH INVENTIONS TO BE EXCLUDED UNDER THIS AGREEMENT, THE EMPLOYEE SHALL INITIAL HERE; OTHERWISE IT WILL BE DEEMED THAT THERE ARE NO SUCH EXCLUSIONS.      The Employee understands that, to the
extent this Agreement shall be construed in accordance with the laws of any state that precludes the requirement in an employee agreement to assign certain classes of inventions made by an employee, this Section 3(b) shall be interpreted not to
apply to any invention that a court 

  
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rules and/or the Company agrees falls within such classes. To the extent allowed by law, the Employee hereby grants to the Company an exclusive (even unto the Employee), irrevocable, fully paid
up, worldwide license to make, use and sell any and all inventions for which assignment cannot be effected. 
 (c) The Employee agrees to
cooperate fully with the Company, both during and after the Employee’s employment with the Company, with respect to the procurement, maintenance and enforcement of all copyrights, trademarks, patents and other intellectual property rights (both
in the United States and foreign countries) relating to any Development. The Employee shall sign all papers, including, without limitation, copyright applications, patent applications, declarations, oaths, formal assignments, assignment of priority
rights and powers of attorney, that the Company may deem necessary or desirable in order to protect and enforce its rights and interests in any Development. The Employee further agrees that if the Company is unable, after reasonable effort, to
secure the signature of the Employee on any such papers, any executive officer of the Company shall be entitled to execute any such papers as the agent and the attorney-in-fact of the Employee, and the Employee hereby irrevocably designates and
appoints each executive officer of the Company as the Employee’s agent and attorney-in-fact for all countries worldwide to execute any such papers on the Employee’s behalf, and to take any and all actions as the Company may deem necessary
or desirable in order to protect its rights and interests in any Development, under the conditions described in this sentence. Should the Company engage in litigation to enforce any such intellectual property rights, the Employee agrees to appear
and testify at no charge, but at the Company’s expense. 
 4. Non-Competition and Non-Solicitation. 

While the Employee is employed by the Company and for a period of twelve (12) months following the Employee’s termination or
cessation of employment for any reason (voluntarily or involuntarily), the Employee will not, directly or indirectly: 
 (a) Engage in any
business or enterprise (whether as an owner, partner, officer, employee, director, investor, lender, consultant, independent contractor or otherwise, except as the holder of not more than 1% of the combined voting power of the outstanding stock of a
publicly held company) that is competitive with the Company’s business, including, without limitation, any business or enterprise that develops, designs, produces, markets or sells any pharmaceutical product designed to treat cancer or renders
any product or service competitive with any product or service developed, designed, produced, marketed or sold or planned to be developed, designed, produced, marketed or sold by the Company while the Employee was employed by the Company; 

(b) Either alone or in association with others, recruit, solicit, hire or engage as an independent contractor, or attempt to recruit, solicit,
hire or engage as an independent contractor, any person who was employed by the Company or engaged as an independent contractor for the Company at any time during the period of the Employee’s employment with the Company, except for an
individual whose employment with or service for the Company has been terminated for a period of six (6) months or longer; and/or 

  
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 (c) Either alone or in association with others, service, solicit, divert or take away, or attempt
to service, solicit, divert or take away, the business or patronage of any of the clients, customers or accounts, or prospective clients, customers or accounts, of the Company that were contacted, solicited or served by the Employee while the
Employee was employed by the Company or about which the Employee had access to Proprietary Information in the course of his/her employment with the Company. 

(d) The geographic scope of this Section 4 shall extend to anywhere the Company or any of its subsidiaries is doing business, has done
business or has plans to do business during the Employee’s employment. 
 (e) If any restriction set forth in this Section 4 is
found by any court of competent jurisdiction to be unenforceable because it extends for too long a period of time or over too great a range of activities or in too broad a geographic area, it shall be interpreted to extend only over the maximum
period of time, range of activities or geographic area as to which it may be enforceable. 
 (f) The Employee agrees that during the
non-competition and non-solicitation period, the Employee will give notice to the Company of each new job, contract assignment or other work (either as an employee, contractor or otherwise) the Employee plans to undertake at least ten
(10) business days prior to beginning any such activity. The notice shall state the name and address of the individual, corporation, association or other entity or organization (the “Entity”) for whom such activity is
undertaken and the Employee’s proposed business relationship or position with the Entity. The Employee further agrees to provide the Company with other pertinent information concerning such business activity as the Company may reasonably
request in order to determine the Employee’s continued compliance with his/her obligations under this Agreement. During the non-competition and non-solicitation period, the Employee agrees to provide a copy of this Agreement to all person and
Entities with whom the Employee seeks to be hired or do business before accepting employment or engagement with any of them. 
 (g) If the
Employee violates any of the provisions of this Section 4, the Employee shall continue to be held by the restrictions set forth in this Section 4 until a period equal to the period of restriction has expired without any violation. 

5. Other Agreements. 
 The Employee hereby
represents that, except as the Employee has disclosed in writing to the Company, the Employee is not bound by the terms of any restrictive covenant agreement with any previous employer or other party relating to the non-disclosure of trade secret or
confidential or proprietary information, non-competition and/or non-solicitation of customers, clients, employees or others. The Employee further represents that the Employee’s performance of all the terms of this Agreement and as an employee
of the Company does not and will not breach any such restrictive covenant agreement, and the Employee will not disclose to the Company or induce the Company to use any confidential or proprietary information or material belonging to any previous
employer or others. 

  
 4 

 6. Employment At Will. 

The Employee acknowledges that this Agreement does not constitute a contract of employment for any period of time and does not modify the
at-will nature of the Employee’s employment with the Company, pursuant to which both the Company and the Employee may terminate the employment relationship at any time, for any or no reason, with or without notice. 

7. General Provisions. 
 (a) Equitable
Relief. The Employee acknowledges that the restrictions contained in this Agreement are necessary for the protection of the business and goodwill of the Company and are considered by the Employee to be reasonable for such purpose. The Employee
agrees that any breach or threatened breach of this Agreement will cause the Company substantial and irrevocable damage that is difficult to measure. Therefore, in the event of any such breach or threatened breach, the Employee agrees that the
Company, in addition to such other remedies that may be available, shall have the right to specific performance and injunctive relief without posting a bond, as well as its reasonable attorneys’ fees incurred as a result of any such breach or
threatened breach. The Employee hereby waives the adequacy of a remedy at law as a defense to such relief. 
 (b) Change in
Terms/Conditions of Employment. The Employee agrees that his/her obligations under this Agreement shall continue in full force and effect in the event that the Employee’s job title, responsibilities, reporting structure, work location,
compensation or other conditions of his/her employment with the Company change subsequent to the execution of this Agreement, without the need to execute a new agreement. 

(c) No Conflict. The Employee represents that the execution and performance by the Employee of this Agreement does not and will not
conflict with or breach the terms of any other agreement by which the Employee is bound. 
 (d) Severability. The invalidity or
unenforceability of any provision of this Agreement shall not affect or impair the validity or enforceability of any other provision of this Agreement. 

(e) Waiver; Amendments. No delay or omission by the Company in exercising any right under this Agreement will operate as a waiver of
that or any other right. A waiver or consent given by the Company on any one occasion is effective only in that instance and will not be construed as a bar to or waiver of any right on any other occasion. Any amendment to or modification of this
Agreement, or any waiver of any provision thereof, shall be in writing and signed by the Company. 
 (f) Successors and Assigns. This
Agreement shall be binding upon and inure to the benefit of both parties and their respective successors and assigns, including, without limitation, any corporation or entity with which or into which the Company may be merged or which may succeed to
all or substantially all of its assets or business; provided, however, that the obligations of the Employee are personal and shall not be assigned by the Employee. 

  
 5 

 (g) Governing Law, Forum and Jurisdiction. This Agreement shall be governed by and
construed as a sealed instrument under and in accordance with the laws of the Commonwealth of Massachusetts without regard to conflict of laws provisions. Any action, suit or other legal proceeding that is commenced to resolve any matter arising
under or relating to any provision of this Agreement shall be commenced only in a court of the Commonwealth of Massachusetts (or, if appropriate, a federal court located within Massachusetts), and the Company and the Employee each consents to the
jurisdiction of such a court. The Employee and the Company hereby expressly waive the right to a jury trial for any claim relating to his/her/its rights or obligations under this Agreement, or otherwise relating to the Employee’s employment
or separation from employment with the Company. 
 (h) Captions. The captions of the sections of this Agreement are for
convenience of reference only and in no way define, limit or affect the scope or substance of any section of this Agreement. 
 (i)
Entire Agreement. This Agreement supersedes all prior agreements, written or oral, between the Employee and the Company relating to the subject matter of this Agreement. This Agreement may not be modified, changed or discharged in whole or in
part, except by an agreement in writing signed by the Employee and the Company. 
 THE EMPLOYEE ACKNOWLEDGES THAT HE/SHE HAS CAREFULLY READ
THIS AGREEMENT AND UNDERSTANDS AND AGREES TO ALL OF THE PROVISIONS IN THIS AGREEMENT. 
 IN WITNESS WHEREOF, the parties hereto have
executed this Agreement as of the date first written above. 
  

							
	COMPANY:				MERRIMACK PHARMACEUTICALS, INC.
				
					By:		 /s/ Robert J. Mulroy

							Robert J. Mulroy
							President and Chief Executive Officer
			
	EMPLOYEE:				 /s/ Birgit M. Schoeberl

					Birgit M. Schoeberl

  
 6 

 Exhibit A 

List of Prior Inventions and Original Works of Authorship 
  

					
	 Title
	  	 Date
	  	 Identifying Number or Brief Description

		  		  	
		  		  	
		  		  	

  

					
	  
	  	Additional Sheets Attached	  	
			
	Signature of Employee:	  	  
	  	
			
	Printed Name of Employee:	  	  
	  	
			
	Date:	  	  
	  	

 Exhibit B 

Definition of Change in Control 
 A
“Change in Control” shall occur upon the following events, provided, in each case, that such event constitutes a “change in control event” within the meaning of Treasury Regulation Section 1.409A-3(i)(5)(i): 

(A) the acquisition by an individual, entity or group (within the meaning of Section 13(d)(3) or 14(d)(2) of the Securities Exchange Act
of 1934, as amended (the “Exchange Act”) (a “Person”) of beneficial ownership of any capital stock of the Company if, after such acquisition, such Person beneficially owns (within the meaning of Rule 13d-3 under the
Exchange Act) 50% or more of either (x) the then-outstanding shares of common stock of the Company (the “Outstanding Company Common Stock”) or (y) the combined voting power of the then-outstanding securities of the Company
entitled to vote generally in the election of directors (the “Outstanding Company Voting Securities”); provided, however, that for purposes of this subsection (A), the following acquisitions shall not constitute a Change in Control
Event: (1) any acquisition directly from the Company or (2) any acquisition by any corporation pursuant to a Business Combination (as defined below) which complies with clauses (x) and (y) of subsection (C) of this
definition; 
 (B) a change in the composition of the Board that results in the Continuing Directors (as defined below) no longer
constituting a majority of the Board (or, if applicable, the Board of Directors of a successor corporation to the Company), where the term “Continuing Director” means at any date a member of the Board (x) who was a member of
the Board on the date of this Agreement or (y) who was nominated or elected subsequent to such date by at least a majority of the directors who were Continuing Directors at the time of such nomination or election or whose election to the Board
was recommended or endorsed by at least a majority of the directors who were Continuing Directors at the time of such nomination or election; provided, however, that there shall be excluded from this clause (y) any individual whose initial
assumption of office occurred as a result of an actual or threatened election contest with respect to the election or removal of directors or other actual or threatened solicitation of proxies or consents, by or on behalf of a person other than the
Board; or 
 (C) the consummation of a merger, consolidation, reorganization, recapitalization or share exchange involving the Company or a
sale or other disposition of all or substantially all of the assets of the Company (a “Business Combination”), unless, immediately following such Business Combination, each of the following two conditions is satisfied: (x) all
or substantially all of the individuals and entities who were the beneficial owners of the Outstanding Company Common Stock and Outstanding Company Voting Securities immediately prior to such Business Combination beneficially own, directly or
indirectly, more than 50% of the then-outstanding shares of common stock and the combined voting power of the then-outstanding securities entitled to vote generally in the election of directors, respectively, of the resulting or acquiring
corporation in such Business Combination (which shall include, without limitation, a corporation which as a result of such transaction owns the Company or substantially all of the Company’s assets either directly or through one or more
subsidiaries) (such resulting or acquiring corporation is referred to herein as the “Acquiring Corporation”) in substantially the same 

 
proportions as their ownership of the Outstanding Company Common Stock and Outstanding Company Voting Securities, respectively, immediately prior to such Business Combination and (y) no
Person (excluding any employee benefit plan (or related trust) maintained or sponsored by the Company or by the Acquiring Corporation) beneficially owns, directly or indirectly, 50% or more of the then-outstanding shares of common stock of the
Acquiring Corporation, or of the combined voting power of the then-outstanding securities of such corporation entitled to vote generally in the election of directors (except to the extent that such ownership existed prior to the Business
Combination). 

 Exhibit C 

Payments Subject to Section 409A 

Subject to this Exhibit C, severance payments or benefits under this Agreement shall begin only on or after the date of the Employee’s “separation
from service” (determined as set forth below), which occurs on or after the termination of the Employee’s employment. The following rules shall apply with respect to distribution of the payments and benefits, if any, to be provided to the
Employee under this Agreement: 
 1. It is intended that each installment of the payments provided under this Agreement shall be treated as a separate
“payment” for purposes of Section 409A of the Internal Revenue Code and the guidance issued thereunder (“Section 409A”). Neither the Company nor the Employee shall have the right to accelerate or defer the delivery of
any such payments or benefits except to the extent specifically permitted or required by Section 409A. 
 2. If, as of the date of the Employee’s
“separation from service” from the Company, the Employee is not a “specified employee” (within the meaning of Section 409A), then each installment of the severance payments and benefits shall be made on the dates and terms
set forth in this Agreement. 
 3. If, as of the date of the Employee’s “separation from service” from the Company, the Employee is a
“specified employee” (within the meaning of Section 409A), then: 
 (a) Each installment of the severance payments and
benefits due under this Agreement that, in accordance with the dates and terms set forth herein, will in all circumstances, regardless of when the Employee’s separation from service occurs, be paid within the Short-Term Deferral Period (as
defined under Section 409A) shall be treated as a short-term deferral within the meaning of Treasury Regulation Section 1.409A- l(b)(4) to the maximum extent permissible under Section 409A and shall be paid at the time set forth in
this Agreement; and 
 (b) Each installment of the severance payments and benefits due under this Agreement that is not described in this
Exhibit C, Section l(c)(i) and that would, absent this subsection, be paid within the six (6) month period following the Employee’s “separation from service” from the Company shall not be paid until the date that is six
(6) months and one (1) day after such separation from service (or, if earlier, the Employee’s death), with any such installments that are required to be delayed being accumulated during the six (6) month period and paid in a lump
sum on the date that is six (6) months and one (1) day following the Employee’s separation from service and any subsequent installments, if any, being paid in accordance with the dates and terms set forth herein; provided, however,
that the preceding provisions of this sentence shall not apply to any installment of severance payments and benefits if and to the maximum extent that such installment is deemed to be paid under a separation pay plan that does not provide for a
deferral of compensation by reason of the application of Treasury Regulation 1.409A-l(b)(9)(iii) (relating to separation pay upon an involuntary separation from service). Any installments that qualify for the exception under Treasury Regulation
Section 1.409A-l(b)(9)(iii) must be paid no later than the last day of the Employee’s second taxable year following the taxable year in which the separation from service occurs. 

 4. The determination of whether and when the Employee’s separation from service from the Company has
occurred shall be made and in a manner consistent with, and based on the presumptions set forth in, Treasury Regulation Section 1.409A-l(h). Solely for purposes of this Exhibit C, Section 4, “Company” shall include all
persons with whom the Company would be considered a single employer under Section 414(b) and 414(c) of the Internal Revenue Code. 
 5. All
reimbursements and in-kind benefits provided under this Agreement shall be made or provided in accordance with the requirements of Section 409A to the extent that such reimbursements or in-kind benefits are subject to Section 409A,
including, where applicable, the requirement that (i) any reimbursement is for expenses incurred during the Employee’s lifetime (or during a shorter period of time specified in this Agreement), (ii) the amount of expenses eligible for
reimbursement during a calendar year may not affect the expenses eligible for reimbursement in any other calendar year, (iii) the reimbursement of an eligible expense will be made on or before the last day of the calendar year following the
year in which the expense is incurred and (iv) the right to reimbursement is not subject to set off or liquidation or exchange for any other benefit. 

6. The Company makes no representation or warranty and shall have no liability to you or to any other person if any of the provisions of this Agreement
(including this Exhibit C) are determined to constitute deferred compensation subject to Section 409A but that do not satisfy an exemption from, or the conditions of, that section. 

7. The Company may withhold (or cause to be withheld) from any payments made under this Agreement, all federal, state, city or other taxes as shall be
required to be withheld pursuant to any law or governmental regulation or ruling.EX-10.15

 Exhibit 10.15 

THIRD AMENDMENT OF LEASE 

THIS THIRD AMENDMENT OF LEASE (this “Amendment”) is made as of this
23rd day of February, 2015 (the “Execution Date”), by and between DWF IV ONE KENDALL, LLC, a Delaware limited liability company having an address c/o Divco West Real
Estate Services, Inc., One Kendall Square, Cambridge, MA 02139, Attention: Property Manager (“Landlord”) and MERRIMACK PHARMACEUTICALS, INC., a Delaware corporation having a mailing address at One Kendall Square,
Building 600/700, Cambridge, MA 02139 (“Tenant”). 
 BACKGROUND: 

A. Reference is made to an Indenture of Lease dated August 24, 2012, by and between RB Kendall Fee, LLC, as landlord, and Tenant, as
tenant (the “Original Lease”), as amended by that certain First Amendment of Lease dated March 18, 2013 and Second Amendment of Lease dated as of September 12, 2013 (the Original Lease, as so amended, the
“Lease”), demising approximately (a) 31,747 rentable square feet of space on a portion of the second floor (2nd) of Building 600/650/700 (the “2nd Floor Space”), (b) 4,773 rentable square feet of space on the fourth (4th) floor of Building 650/700 (the
“Additional Space”), (c) 30,626 rentable square feet of space on the fourth (4th) floor of Building 600/700 (the “4th Floor Space”), (d) 7,245 rentable square feet of space on the mezzanine level of Building 700 (the “Mezzanine Space”), (e) 8,686 rentable square feet
of space on the first (1st) floor of Building 600 (the “1st Floor Space”), (f) 132 rentable square feet in
the basement of Building 600/650/700 (the “Basement Premises”), (g) 2,922 rentable square feet of space in the basement of Building 600/650/700 (the “Storage Space”), (h) 8,763 rentable
square feet of space located on the fourth (4th) floor of Building 700 (the “Expansion Space I”), (i) 3,388 rentable square feet of space located on the fourth (4th) floor and the fourth (4th) floor mezzanine of Building 650 (the “Expansion Space II”), (j) 10,375
rentable square feet of space located on the fifth (5th) floor of Building 600 (the “Expansion Space III”), (k) 491 rentable square feet of space on the (1st) floor of Building 600/650/700 (the “Chemical Storage Space”), (l) 8,155 rentable square feet of space located on the second (2nd) floor of Building 600 (the “600 Expansion Space”), (m) 784 rentable square feet of space located on the second floor
(2nd) of Building 600 (the “Hallway Space”), and (n) 3,617 rentable square feet of space located on the fifth
(5th) floor of Building 600 (the “Expansion Space IV;” collectively, with the 2nd Floor Space, Additional Space, 4th Floor Space, Mezzanine Space, 1st Floor Space, Basement Premises, Storage Space, Expansion Space I, Expansion Space II, Expansion Space III,
Chemical Storage Space, 600 Expansion Space and the Hallway Space, the “Existing Premises”) in One Kendall Square, Cambridge, Massachusetts. 

B. Landlord is the successor to RB Kendall Fee, LLC, and Landlord and Tenant are the current holders, respectively, of the landlord’s and
tenant’s interests in the Lease. 
 C. The parties desire to execute this Amendment to (i) confirm the exercise of Tenant’s
rights pursuant to Article 29.16 of the Original Lease so as to add to the Existing Premises an additional approximately 31,620 rentable square feet of space on the fifth (5th) floor of Building No. 600/650/700 of the Complex,
(ii) acknowledge that the 220 rentable square feet of storage space in the basement of Building 600/650/700 of the Complex referenced in the right of first offer to lease dated December 5, 2014 is not to be included as part of the
Premises, and (iii) amend the Lease in certain other respects, all as hereinafter set forth. Capitalized terms not defined herein shall have the same meanings ascribed to them in the Lease. 

  
 1 

 AGREEMENTS: 

NOW, THEREFORE, in consideration of the mutual covenants and agreements herein contained, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant hereby agree to amend the Lease as follows: 
 1. Inclusion
of Third Amendment Premises; the Third Amendment Premises Term. Effective as of the date that Landlord delivers possession of the Third Amendment Premises (as such term is defined below) in the condition required pursuant to Section 2 below
to Tenant (the “Third Amendment Premises Commencement Date”), there shall be added to the Existing Premises under the Lease the approximately 31,620 rentable square feet of space on the fifth (5th) floor of Building No. 600/650/700 of the Complex more particularly shown on Exhibit 2E attached hereto as the “Third Amendment Premises” (the “Third Amendment
Premises”). Landlord anticipates delivering possession of the Third Amendment Premises to Tenant on or before September 1, 2015 (the “Anticipated Delivery Date”); provided, however, that if Landlord cannot
deliver possession of the Third Amendment Premises to Tenant in the condition required under Section 2 below on or before the Anticipated Delivery Date due to the failure of the existing tenant of the Third Amendment Premises (the
“Existing Tenant”) to vacate the Third Amendment Premises or due to fire or other casualty (provided, that in the event of any such fire or other casualty, the provisions of Section 18 of the Original Lease shall apply),
this Amendment shall not be void or voidable, nor shall Landlord be liable for any loss or damage resulting therefrom. In any event, there shall be no accrual of Yearly Rent, Tax Share or Operating Expense Share (subject in each instance to the
provisions hereof) with respect to the Third Amendment Premises until Landlord delivers possession of the Third Amendment Premises to Tenant. Landlord shall use reasonable efforts to deliver possession of the Third Amendment Premises to Tenant as
soon as reasonably practicable following the date the Existing Tenant vacates the Third Amendment Premises, regardless of whether such date occurs prior to the Anticipated Delivery Date and any such earlier date of delivery shall be the Third
Amendment Premises Commencement Date. In the event that Landlord cannot deliver possession of the Third Amendment Premises to Tenant on or before the Anticipated Delivery Date in the condition required under Section 2 below due to the failure
of the Existing Tenant to vacate the Third Amendment Premises, then Landlord shall use commercially reasonable efforts to cause the Existing Tenant to vacate the Third Amendment Premises. To the extent not caused by Landlord, Tenant’s inability
or failure to take possession of the Third Amendment Premises when delivery is tendered by Landlord in the condition required under Section 2 below shall not delay the Third Amendment Premises Commencement Date or Tenant’s obligation to
pay Yearly Rent with respect thereto. 
 Notwithstanding the foregoing, if the Third Amendment Premises Commencement Date does not occur
within one hundred eighty (180) days of the Anticipated Delivery Date (such 180th day being the “Delivery Deadline”) except if due to fire or other casualty that is
not caused by Landlord’s gross negligence or willful misconduct, Landlord shall provide Tenant with a credit of one (1) day’s Yearly Rent, Tax Share and Operating Expense Share allocable to the Third Amendment Premises for each day
beyond the Delivery Deadline until the Third Amendment Premises Commencement Date occurs and if the Third Amendment Premises Commencement Date does not occur within ninety (90) days of the Delivery Deadline (such 90th day being the “Second Delivery Deadline”), such credit shall increase to two (2) day’s Yearly Rent, Tax Share and Operating Expense Share allocable to the Third
Amendment Premises for each day beyond the Second Delivery Deadline until the Third Amendment Premises Commencement Date occurs. The foregoing credits shall be applied on a day-for-day basis to Tenant’s rent obligations for the Third Amendment
Premises beginning on the Third Amendment Premises Rent Commencement Date. 
 Accordingly, as of the Third Amendment Premises Commencement
Date, Article 2 of Exhibit 1, Sheet 1 of the Original Lease shall be amended to add the following after the last paragraph thereof: 

“Third Amendment Premises: Approximately 31,620 rentable square feet of space on the fifth
(5th) floor of Building No. 600/650/700 of the Complex more particularly shown on Exhibit 2E to the Third Amendment of Lease entitled “Third Amendment Premises.” 

  
 2 

 The term of the lease for the Third Amendment Premises shall be the period beginning on the Third
Amendment Premises Commencement Date and ending on June 30, 2019 (the “Third Amendment Term”), subject to the provisions of Section 9 of this Amendment. 

Except as otherwise provided herein or except to the extent inconsistent herewith, all terms and provisions of the Lease shall be applicable
to Tenant’s leasing of the Third Amendment Premises. As of the Third Amendment Premises Commencement Date, the Premises under the Lease shall consist of the Existing Premises and the Third Amendment Premises. 

2. “As-Is” Condition. The Third Amendment Premises shall be leased to Tenant as of, and Landlord shall deliver possession
thereof to Tenant on, the Third Amendment Premises Commencement Date in its “as is” condition as of the date of this Amendment (provided that the same shall be in broom clean condition and free of all tenants and/or occupants and their
personal property, and provided further that decommissioning reports from the Existing Tenant have been delivered to Tenant in advance of the Third Amendment Premises Commencement Date evidencing that the Third Amendment Premises have been
decommissioned in accordance with applicable laws), without any obligation on the part of Landlord to perform any construction therein or to prepare the same for Tenant’s occupancy or otherwise or to pay any allowances therefor, except for the
payment of the Third Amendment Landlord Contribution as set forth below. 
 3. Payment of Yearly Rent for Third Amendment Premises.
For and during the Third Amendment Term (i.e., the period commencing on the Third Amendment Premises Commencement Date and ending on June 30, 2019), in addition to all other amounts due and payable by Tenant under the Lease with respect
to the Existing Premises, Tenant shall pay to Landlord monthly installments of Yearly Rent with respect to the Third Amendment Premises as follows and otherwise as set forth in the Yearly Rent payment provisions of the Lease: 

 

					
	 Time Period
	  	Monthly
Payment of Yearly Rent	 
	 Month 1 through the end of Month 3:
	  	$	0.00	1 
	 Month 4 through the end of Month 15:
	  	$	148,877.50	  
	 Month 16 through the end of Month 27:
	  	$	151,512.50	  
	 Month 28 through the end of Month 39:
	  	$	154,147.50	  
	 Month 40 through the end of June 30, 2019:
	  	$	156,782.50	  

  

	1 	Month 1 shall begin on the Third Amendment Premises Commencement Date if the Third Amendment Premises Commencement Date occurs on the first day of a calendar month, and if the Third Amendment Premises Commencement Date
shall not be the first day of a calendar month, (a) Month 1 shall instead begin on the first full calendar month after the calendar month during which the Third Amendment Premises Commencement Date occurs, and (b) Tenant shall nevertheless
be responsible for payment of the partial month of Yearly Rent for the Third Amendment Premises prior to Month 1 on a pro rata basis at the monthly rate of $148,877.50. 

  
 3 

 4. Operating Expense Share and Tax Share for Third Amendment Premises. Commencing on the
first day of Month 4 with respect to the Third Amendment Premises pursuant to Section 3 above (the “Third Amendment Premises Rent Commencement Date”), Tenant shall make Tax Share and Operating Expense Share payments
attributable to the Third Amendment Premises in accordance with the terms and conditions of the Lease, as amended hereby. The parties acknowledge and agree that Tenant shall have no responsibility under the Lease, as amended hereby, for
Tenant’s Tax Share and Operating Expense Share attributable to the Third Amendment Premises for the period from the Third Amendment Premises Commencement Date through the day prior to the Third Amendment Premises Rent Commencement Date. 

5. Proportionate Shares as of Third Amendment Premises Rent Commencement Date. Effective as of the Third Amendment Premises Rent
Commencement Date and continuing for the Third Amendment Term (i.e., the period commencing on the Third Amendment Premises Rent Commencement Date and ending on June 30, 2019), Article 9 of Exhibit 1, Sheet 1 of the Lease is amended to
read in its entirety as follows: 
 Art. 9 Operating and Taxes: 
  

					
	 Tenant’s Proportionate Common Area Share:
				
		
	 2nd Floor Space, Additional Space,
4th Floor Space and Mezzanine Space:
		 	11.61	% 
	 1st Floor Space:
		 	1.36	% 
	 Expansion Space I:
		 	1.37	% 
	 Expansion Space II:
		 	0.53	% 
	 Expansion Space III:
		 	1.62	% 
	 Expansion Space IV:
		 	0.56	% 
	 Chemical Storage Space:
		 	0.08	% 
	 600 Expansion Space and Hallway Space:
		 	1.39	% 
	 Third Amendment Premises:
		 	4.90	% 
		
	 Tenant’s Proportionate Building Share:
				
		
	 2nd Floor Space, Additional Space,
4th Floor Space and Mezzanine Space:
		 	32.94	% 
	 1st Floor Space:
		 	3.85	% 
	 Expansion Space I:
		 	3.88	% 
	 Expansion Space II:
		 	1.50	% 
	 Expansion Space III:
		 	4.59	% 
	 Expansion Space IV:
		 	1.60	% 
	 Chemical Storage Space:
		 	0.22	% 
	 600 Expansion Space and Hallway Space:
		 	3.96	% 
	 Third Amendment Premises:
		 	14.00	% 

  
 4 

 6. Permitted Uses of Premises. 

(a) Effective as of the Execution Date of this Amendment, Article 5 of Exhibit 1, Sheet 1 of the Original Lease is amended to read in its
entirety as follows: 
 “Art. 5 Permitted Uses of Premises: 

2nd Floor Space, Additional Space,
4th Floor Space, 1st Floor Space, Expansion Space I, Expansion Space II, Expansion Space III, Expansion Space IV, 600 Expansion Space, Hallway
Space and Third Amendment Premises: General business offices, laboratory use (including, without limitation, animal laboratory use), manufacturing, shipping and receiving purposes and ancillary uses thereto subject to Section 29.11 of the
Original Lease, Section 10 of this Amendment and the other provisions of the Lease. 
 Basement Premises: Operation of the Ph
Neutralization system and for no other purpose. 
 Mezzanine Space: General business offices and for no other purpose. 

Storage Space: For the storage of Tenant’s personal property (excluding chemical storage) relating to the Permitted Use of the
Premises. 
 Chemical Storage Space: Solely for storage, including, without limitation, storage of chemicals used in connection with
Tenant’s business operations in the remainder of the Premises. The use of the Chemical Storage Space and storage of all such chemicals shall be in compliance with all applicable laws and otherwise in compliance with all the terms of the Lease,
including, without limitation, Section 29.11 of the Original Lease, Section 10 of this Amendment and the other provisions of the Lease. 

7. Electric Current to Third Amendment Premises. From and after the Third Amendment Premises Commencement Date, (i) in the event
that electricity consumption for the Third Amendment Premises is separately metered, Tenant shall pay, directly to the appropriate utility provider, any and all costs of electricity utilized in or for the Third Amendment Premises and in support of
any of Tenant’s equipment, wherever located, or (ii) in the event that electricity consumption for the Third Amendment Premises is measured by a checkmeter, sub-meter or other measuring device, Tenant shall pay to Landlord, as additional
rent, the amount as determined below. 
  

	 	(a)	Commencing as of the Third Amendment Premises Commencement Date and continuing until the procedures set forth in the immediately following Section 7(b) are in effect, Tenant shall pay to Landlord at the same time
and in the same manner that it pays its monthly payments of Yearly Rent hereunder, estimated payments (i.e., based upon Landlord’s reasonable estimate) on account of Tenant’s obligation to reimburse Landlord for electricity consumed in the
Third Amendment Premises. 

  

	 	(b)	Periodically after the Third Amendment Premises Commencement Date, Landlord shall determine the actual cost of electricity consumed by Tenant in the Third Amendment Premises (i.e., by reading Tenant’s
sub-meter and by applying an electric rate which shall not exceed the rate at which Landlord purchases electricity, including taxes and surcharges thereon). If the total of Tenant’s estimated monthly payments on account of such period is less
than the actual cost of electricity consumed in the Third Amendment Premises during such period, Tenant shall pay the difference to Landlord within thirty (30) days of when billed therefor. If the total of Tenant’s estimated monthly
payments on account of such period is greater than the actual cost of electricity consumed in the Third Amendment Premises during such period, Tenant may credit the difference against its next installment of estimated monthly electricity charges due
hereunder, provided that any excess credit shall be repaid to Tenant within thirty (30) days following the expiration of the Third Amendment Term provided Tenant is not in default under the Lease. 

  
 5 

	 	(c)	After each adjustment, as set forth in Section 7(b) above, the amount of estimated monthly payments on account of Tenant’s obligation to reimburse Landlord for electricity in the Third Amendment Premises shall
be adjusted by Landlord based upon the actual cost of electricity consumed during the immediately preceding period. 

 8.
Extension Options Applicable to Third Amendment Premises. For the sake of clarity, the extension options set forth in Section 29.14 of the Original Lease shall apply to the Existing Premises and the Third Amendment Premises; provided,
however, Tenant shall not have the right to exercise an extension option for less than all of the Premises (i.e., the Existing Premises and the Third Amendment Premises). 

9. Third Amendment Allowance.
  

	 	(a)	Tenant plans to complete certain Tenant’s leasehold improvements to the Premises (the “Tenant’s Third Amendment Work”) in accordance with the terms and conditions of the Lease (as
amended hereby). In connection with the Tenant’s Third Amendment Work, Landlord shall provide to Tenant an allowance equal to $790,500.00 (the “Third Amendment Landlord Contribution”) toward the cost of the design and
construction of Tenant’s Third Amendment Work. The Third Amendment Landlord Contribution shall be paid, and requests therefor shall be made, in the manner provided in Section 4.2 of the Original Lease, and shall otherwise be treated in the
same manner as the “Landlord’s Contribution” as described in the Original Lease; provided, however, that with respect to the Third Amendment Landlord Contribution, (a) all references in the Original Lease to
(i) “Landlord’s Contribution” shall be deemed to refer to the Third Amendment Landlord Contribution, (ii) “Tenant’s Work” shall be deemed to refer to the Tenant’s Third Amendment Work, and
(iii) “Plans and Specifications” shall be deemed to refer to the “Third Amendment Plans and Specifications” (as defined below), (b) the first sentence of Section 4.2B and Sections 4.2D(iii) and 4.2D(iv) of the
Original Lease shall be inapplicable to the Third Amendment Landlord Contribution, and (c) Tenant shall have no right to requisition any portion of the Third Amendment Landlord Contribution after the second (2nd) anniversary of the Third Amendment Premises Rent Commencement Date. 

  

	 	(b)	The Tenant’s Third Amendment Work shall be constructed in accordance with the terms and conditions of the Original Lease including but not limited to Section 4.2A and Articles 11, 12 and 13 of the Original
Lease. Without limiting the foregoing, Tenant shall obtain Landlord’s prior written consent, in accordance with the provisions of Section 4.2A of the Original Lease, for all of the Tenant’s Third Amendment Work (and Third Amendment
Plans and Specifications therefor), and the contractors, engineers, architects, technicians and mechanics effecting same, which consent shall not be unreasonably withheld, conditioned or delayed. Tenant shall be responsible for the preparation of
construction plans and specifications, including but not limited to architectural, mechanical, electrical, plumbing, life-safety and other Buildings systems and interfaces therewith (collectively, the “Third Amendment Plans and
Specifications”) and any specialty engineering necessary for the completion of the Tenant’s Third Amendment Work, all of which shall be subject to Landlord’s prior written consent, which consent shall not be unreasonably
withheld conditioned or delayed, in accordance with the provisions of Section 4.2A of the Original Lease. Landlord shall be entitled to deduct from the Third Amendment Landlord Contribution all direct, reasonable third-party out-of-pocket
expenses incurred by Landlord in reviewing and approving the Third Amendment Plans and Specifications following delivery of detailed invoices for same to Tenant. 

  
 6 

 10. Hazardous Materials. 

 

	 	(a)	Landlord and Tenant acknowledge and agree that all of the provisions of Section 29.11 of the Original Lease shall apply to the Third Amendment Premises in the same manner as the Existing Premises. Notwithstanding
the foregoing, unless and until Tenant and Landlord amend Exhibit 7A to the Original Lease to include a matrix specifying the quantities of Hazardous Materials subject to regulation under 780 CMR 307 that Tenant may use and store in the 600
Expansion Space or the Hallway Space, Tenant shall not use or store in the 600 Expansion Space or the Hallway Space, respectively, any Hazardous Materials except those that are (i) typically used in the ordinary course of business in an office
and for use in the manner for which they were designed and in such limited amounts as may be normal, customary and necessary for the ordinary course of business in an office, and (ii) in full compliance with Environmental Laws. Except as
identified on Exhibit 7 to the Original Lease, Tenant shall not use or store in the Premises (i.e., the Existing Premises and the Third Amendment Premises) any of the Hazardous Materials or classes thereof listed and/or identified on
Schedule 1 attached hereto without Landlord’s prior written consent; provided, however, that Landlord’s prior written consent shall not be unreasonably withheld, conditioned or delayed so long as (A) Tenant has obtained and
maintains all licenses, permits, registrations and consents required by applicable law (including, without limitation, Environmental Laws) to use or store all such types and quantities of Hazardous Materials in the Premises, and (B) within ten
(10) business days of Landlord’s written request from time to time, Tenant shall have provided Landlord with a revised, updated Exhibit 7 reflecting the reasonable adjustments made by Tenant. 

 

	 	(b)	To the extent that Landlord receives any decommissioning report from the tenant currently occupying the Third Amendment Premises, Landlord shall deliver a copy of such report to Tenant as a courtesy and without any
representation or warranty as to the accuracy or sufficiency thereof; provided, further, that Tenant shall have no right to rely on any such report. 

11. Parking. As of the date of this Amendment, Tenant is entitled to a total of one hundred four (104) parking passes in the OKS
Garage, as set forth in Section 29.19 of the Original Lease. As of the Third Amendment Premises Commencement Date, the number of OKS Garage parking passes that Landlord is required to make available to Tenant shall be increased by an additional
thirty (30) parking passes for a total of one hundred thirty-four (134) parking passes. All parking passes shall continue to be available to Tenant pursuant to the terms and provisions of Section 29.19 of the Original Lease,
including, but not limited to, payment of the then current prevailing monthly charge therefor, which as of the Execution Date is $260 per month. 

12. Exclusion of Storage Space from Right of First Offer. Tenant and Landlord agree that the 220 rentable square feet of storage space
in the basement of Building 600/650/700 of the Complex referenced in the Right of First Refusal Offer to Lease dated December 5, 2014 is not included as part of the Premises that Tenant leases from Landlord, and that Landlord is free to rent
such storage space to other parties. 
 13. Amendments to EXHIBIT 1, SHEET 1 of the Original Lease. EXHIBIT 1, SHEET 1 of the
Original Lease is hereby amended as follows: 

  
 7 

	 	(a)	The mailing address for Landlord under EXHIBIT 1, SHEET 1 shall be deleted and the following shall be substituted therefor: 

  

			
	 Landlord Mailing

Address:
		 DWF IV One Kendall, LLC
 c/o Divco West Real
Estate Services, Inc.
 One Kendall Square
 Cambridge, MA
02139
 Attention: Property Manager
  

	 With copies to:
		 DWF IV One Kendall, LLC
 c/o Divco West Real
Estate Services, Inc.
 575 Market Street, 35th Floor

San Francisco, CA 94105
 Attn: Asset Manager

 
 and
  

Nutter, McClennen & Fish LLP
 Seaport West

155 Seaport Boulevard
 Boston, MA 02210

Attn: Timothy M. Smith, Esq.

  

	 	(b)	The following shall be inserted as the Rent Payment Address under EXHIBIT 1, SHEET 1 of the Original Lease:  

“Rent Payment Address: Tenant shall make rent and other payments under the Lease in accordance with the instructions and to the
addresses as noted below, which payment instructions and addresses may be changed by written notice from Landlord to Tenant. 
  

	 	(1)	Tenant shall make all checks, in payment of rent and other sums due to Landlord under this Lease, payable to the order of DWF IV ONE KENDALL, LLC, as mortgagor, for the benefit of GERMAN AMERICAN CAPITAL CORPORATION, as
mortgagee, Account No. 432916030 and 

  

	 	(2)	Tenant shall deliver such checks or otherwise make such payment as follows: 

 By
Mail: 
 City National Bank 

P.O. Box 7129 

San Francisco, CA 94120-7502 

By Wire: 
  

			
	Account Name:		DWF IV One Kendall, LLC
	Account Number:		432916030
	Bank Name:		City National Bank – CBS/SF
	Bank Address:		150 California Street, 13th Floor
			San Francisco, CA 94111
			USA
	ABA Routing #:		1220-1606-6
	Swift #:		CINAUS6L
	Contact:		Hoa Pham (415) 284-5700”

  
 8 

 14. Broker. Landlord and Tenant each represents and warrants to the other party that it
has not authorized, retained or employed, or acted by implication to authorize, retain or employ, any real estate broker or salesman to act for it or on its behalf in connection with this Amendment so as to cause the other party to be responsible
for the payment of a brokerage commission, except for Cushman & Wakefield of Massachusetts, Inc. and Colliers International New England LLC (collectively, the “Brokers”). Any fees payable to the Brokers are the
responsibility of Landlord pursuant to separate written agreement with the Brokers. Landlord and Tenant shall each indemnify, defend and hold the other party harmless from and against any and all claims by any real estate broker or salesman (other
than the Brokers) whom the indemnifying party authorized, retained or employed, or acted by implication to authorize, retain or employ, to act for the indemnifying party in connection with this Amendment. 

15. Counterpart Execution. This Amendment may be executed in counterparts, each of which shall be deemed an original and all of which
when taken together shall constitute one fully executed original Amendment, binding upon the parties hereto, notwithstanding that all of the parties hereto may not be signatories to the same counterpart. Additionally, telecopied or e-mailed
signatures may be used in place of original signatures on this Amendment. Landlord and Tenant intend to be bound by the signatures on the telecopied or e-mailed document, are aware that the other party will rely on the telecopied or e-mailed
signatures, and hereby waive any defenses to the enforcement of the terms of this Amendment based on the form of signature. 
 16.
Miscellaneous. In all other respects, the Lease shall remain unmodified and shall continue in full force and effect, as amended hereby. The parties hereby ratify, confirm, and reaffirm all of the terms and conditions of the Lease, as amended
hereby. 
 17. Authorization to Execute. Tenant represents and warrants to Landlord that the person signing this Amendment on
behalf of Tenant is duly authorized to execute and deliver this Amendment on behalf of Tenant. Landlord represents and warrants to Tenant that the person signing this Amendment on behalf of Landlord is duly authorized to execute and deliver this
Amendment on behalf of Landlord. 
 18. No Reservation. Preparation of this Amendment by Landlord or Landlord’s attorney and the
submission of this Amendment to Tenant for examination or signature is without prejudice and does not constitute a reservation, option or offer to lease the Premises. This Amendment shall not be binding or effective until this Amendment shall have
been executed and delivered by each of the parties hereto, and Landlord reserves the right to withdraw this Amendment upon written notice to Tenant from consideration or negotiation at any time prior to Landlord’s execution and delivery of this
Amendment, which withdrawal shall be without prejudice, recourse or liability. 
 [Signatures on Following Page] 

  
 9 

 IN WITNESS WHEREOF the parties hereto have executed this Third Amendment of Lease on the date
first written above in multiple copies, each to be considered an original hereof, as a sealed instrument. 
  

					
	LANDLORD:
	
	DWF IV ONE KENDALL, LLC, a Delaware limited liability company
			
			By:		Divco West Real Estate Services, Inc.,
					a Delaware corporation, its Agent

  

			
		
	By:		 /s/ James Teng

	Name:		James Teng
	Title:		Managing Director
	
	TENANT:
	
	MERRIMACK PHARMACEUTICALS, INC., a Delaware corporation
		
	By:		 /s/ Jeffrey A. Munsie

	Name:		Jeffrey A. Munsie
	Title:		General Counsel

  
 10 

 EXHIBIT 2E – OUTLINE OF THIRD AMENDMENT PREMISES 

This plan is intended only to show the general outline of the Third Amendment Premises as of the date of this Amendment. Any depiction of interior windows,
walls, cubicles, modules, furniture and equipment on this plan is for illustrative purposes only, but does not mean that such items exist. Landlord is not required to provide, install or construct any such items. It does not in any way supersede any
of Landlord’s rights set forth in the Lease or this Amendment with respect to arrangements and/or locations of public parts of the Building. It is not necessarily to scale; any measurements or distances shown should be taken as approximate. The
inclusion of elevators, stairways, electrical and mechanical closets, and other similar facilities for the benefit of occupants of the Building does not mean such items are part of the Third Amendment Premises. 

 
  
 

 

  
 Exhibit 2E, Page 1 

 SCHEDULE 1 – – PROHIBITED HAZARDOUS MATERIALS 

1. Selected biological agents and toxins (Select Agents) as defined by the Federal Select Agent Program
(http://www.selectagents.gov/) which have the potential to pose a severe threat to public, animal or plant health or to animal or plant products and require registration to possess, use or transfer. Select Agents are regulated under 7CFR
Part 331, 9 CFR Part 121 and 42 CFR Part 73.
 2. Chemicals that present a high level of security risk under the April 2007
Department of Homeland Security – Chemical Facilities Anti-Terrorism Standards (CFATS) regulation (http://www.dhs.gov/identifying-facilities-covered-chemical-security-regulation), that are at or above the applicable Screening Threshold
Quantity. 
 3. The following chemicals and classes of chemicals: 

 

	 	•	 	Perchloric Acid 

  

	 	•	 	Explosive Materials (require ATF license) 

  

	 	•	 	Organic Peroxide Unclassified Detonable: Organic peroxides that are capable of detonation. These peroxides pose an extremely high explosion hazard through rapid explosive decomposition. 

 

	 	•	 	Organic Peroxide Class 1: Those formulations that are capable of deflagration but not detonation. 

  

	 	•	 	Oxidizer Class 4: An oxidizer that can undergo an explosive reaction due to contamination or exposure to thermal or physical shock. Additionally, the oxidizer will enhance the burning rate and can cause
spontaneous ignition of combustibles. 

  

	 	•	 	Pyrophoric Material: A chemical with an auto ignition temperature in air, at or below a temperature of 130°F (54.4°C). 

 

	 	•	 	Reactive Class 4: Materials that in themselves are readily capable of detonation or explosive decomposition or explosive reaction at normal temperatures and pressures. This class includes materials that are
sensitive to mechanical or localized thermal shock at normal temperatures and pressures. 

  

	 	•	 	Reactive Class 3: Materials that in themselves are capable of detonation or of explosive decomposition or explosive reaction but which require a strong initiating source or which must be heated under confinement
before initiation. This class includes materials that are sensitive to thermal or mechanical shock at elevated temperatures and pressures.

  

	 	•	 	Water Reactive Class 3: Materials that react explosively with water without requiring heat or confinement. 

4. Radioactive Materials and Devices as regulated in 105 CMR 120 Radiation Control Program. 

  
 Schedule 1

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