EX-10.18



 Exhibit 10.18 

April 13, 2016 
 Susan E. Graf 

17 Dege Farm Road 
 Califon, NJ 07830 

Dear Susan: 
 It is my pleasure to extend to you this offer of
employment with Epizyme, Inc. (the “Company”). On behalf of the Company, I am pleased to set forth below the terms of your employment with the Company: 
  

	 	1.	Employment. You will be employed to serve on a full-time basis as the Company’s Chief Business Officer, commencing on a date on or prior to April 25, 2016 as may be mutually agreed by you and the
Company (such date being the “Start Date”). As Chief Business Officer, you will be responsible for such duties as are consistent with such position, plus such other duties as may from time to time be assigned to you by the Company. You
shall report to the President and Chief Executive Officer, and you agree to devote your full business time, best efforts, skill, knowledge, attention and energies to the advancement of the Company’s business and interests and to the performance
of your duties and responsibilities as an employee of the Company. You agree to abide by the rules, regulations, instructions, personnel practices and policies of the Company and any changes therein that may be adopted from time to time by the
Company. 

  

	 	2.	Base Salary. Your base salary will be at the rate of $15,208.33 per semi-monthly pay period (which if annualized equals $365,000), less all applicable taxes and withholdings, to be paid in
installments in accordance with the Company’s regular payroll practices. Such base salary may be adjusted from time to time in accordance with normal business practices and in the sole discretion of the Company. 


 

	 	3.	Discretionary Bonus. Following the end of each fiscal year and subject to the approval of the Company’s Board of Directors or a committee of the Board of Directors (the “Board”), you
may be eligible for a retention and performance bonus, based on your performance and the Company’s performance during the applicable fiscal year, as determined by the Company in its sole discretion. The bonus payable to you for 2016, if any,
will be prorated to reflect the portion of 2016 for which you served as Chief Business Officer of the Company. Your target bonus is 40% of your annualized base salary. Such target bonus may be adjusted from time to time in accordance with
normal business practices and in the sole discretion of the Company. You must be an active employee of the Company on the date any bonus is distributed in order to be eligible for and to earn a bonus award, as it also serves as an incentive to
remain employed by the Company.  









	 	4.	Equity. On your Start Date, you will receive a stock option grant under the Company’s 2013 Stock Incentive Plan (the “Plan”) for the purchase of 178,642 shares of common stock of the Company
at an exercise price per share equal to the fair market value of one share of Common Stock on the date of the grant as determined by the Company in its sole discretion. The stock option grant shall be subject to all terms and other provisions set
forth in the Plan and in a separate stock option agreement, including the vesting schedule. The stock option agreement will provide that the option will vest over a four-year period with the first quarter of the underlying shares vesting on the
first anniversary of the Start Date and the remaining three-fourths of the underlying shares vesting monthly in 36 equal monthly installments following the first anniversary of the Start Date until fully vested on the fourth anniversary of the Start
Date. 

 You may also be eligible for other grants of stock or stock options as determined by and in the sole discretion of the
Board. Nothing in this section shall affect your status as an employee at will, as set for below. 
  

	 	5.	Relocation. You will also receive an additional one-time payment of $200,000 for relocation expenses on the first payroll after the Start Date, less all applicable
taxes and withholdings. If you resign from the Company voluntarily for any reason or are terminated by the Company for Cause (as defined under the Company’s Executive Severance and Change in Control Plan) on or prior to the first anniversary of
the Start Date, you will be responsible to repay to the Company100% of the relocation one-time payment ($200,000) less applicable taxes. If you resign from the Company voluntarily for any reason or are
terminated by the Company for Cause after the first anniversary of the Start Date, but on or prior to the second anniversary of the Start Date (months 13-24), you will be responsible to repay a pro-rata monthly portion, of $100,000 less applicable taxes. We will provide temporary housing, airfare, or hotel for you for your travel to and from the office between the Start Date and your actual move to the
greater Boston area in order to facilitate your relocation to the greater Boston area until August 31, 2016. Taxes associated with travel, hotel, and temporary housing benefit will be paid on your behalf by the Company. Any amounts owed by you
to the Company under this Section 5 as a result of you ceasing to be an employee of the Company shall be repaid within 60 days of the date you cease to be an employee of the Company, and the Company shall have the right to offset such amounts
against any amounts it owes you under this letter, the Company’s Executive Severance and Change in Control Plan or otherwise. 

  

	 	6.	Benefits. You may participate in any and all benefit programs that the Company establishes and makes available to its employees from time to time, provided that you are eligible under (and subject to all
provisions of) the plan documents that govern those programs. Benefits are subject to change at any time in the Company’s sole discretion. 









	 	7.	Vacation. You will be eligible for a maximum of three (3) weeks of paid vacation per calendar year to be taken at such times as may be approved in advance by the Company. The number of vacation days
for which you are eligible shall accrue at the rate of 1.25 days per month that you are employed during such calendar year. Your accrual and use of vacation time will be pursuant to Company policy, as established and as may be modified in the sole
discretion of the Company from time to time. 

  

	 	8.	Invention, Non-Disclosure, Non-Competition and Non-Solicitation Obligations. In exchange for your employment with the Company pursuant to the terms and conditions herein, you hereby
acknowledge and affirm your obligations set forth in the enclosed Invention and Non-Disclosure Agreement to be executed for the benefit of the Company, which obligations remain in full force and effect
and is a condition to your employment with the Company. 

  

	 	9.	At-Will Employment. This letter shall not be construed as an agreement, either express or implied, to employ you for any stated term, and shall in no way alter the
Company’s policy of employment at-will, under which both the Company and you remain free to end the employment relationship for any reason, at any time, with or without cause or notice. Similarly, nothing
in this letter shall be construed as an agreement, either express or implied, to pay you any compensation or grant you any benefit beyond the end of your employment with the Company, except as otherwise explicitly set forth herein. This letter
supersedes all prior understandings, whether written or oral, relating to the terms of your employment. 

  

	 	10.	Severance Benefits. In recognition of your position with and value to the Company, and to provide you with assurance in the event of certain employment terminations, you have been selected to
participate in the Company’s Executive Severance and Change in Control Plan, as amended from time to time, a copy of which is enclosed with this letter. 








 If this letter correctly sets forth the terms under which you will be employed by the Company, please sign and
return to me, no later than April 15, 2016, the enclosed duplicate of this letter and the Invention and Non-Disclosure Agreement. 

 

			
	 Sincerely,

		
	By:	 	 /s/ Robert Basemore

		 	Robert Bazemore
		 	President and Chief Executive Officer


 The foregoing correctly sets forth the terms of my at-will employment with
Epizyme, Inc. I am not relying on any representations other than those set forth above. 
  

															
	 /s/ Susan E. Graf
	 		 		 		 		 		 		 	  

	Susan E. Graf	 		 		 		 		 		 		 	Date