Document:

EX-10.4

 Exhibit 10.4 
 EpiZyme, Inc. 
 Restricted Stock Agreement  

Granted Under 2008 Stock Incentive Plan 
 AGREEMENT made this             day of             , 20     ,
between EpiZyme, Inc., a Delaware corporation (the “Company”), and             (the “Participant”). 

For valuable consideration, receipt of which is acknowledged, the parties hereto agree as follows: 

1. Purchase of Shares. 
 The Company shall issue and sell to the Participant, and the Participant shall purchase from the Company, subject to the terms and conditions set forth in this Agreement and in the Company’s 2008
Stock Incentive Plan (the “Plan”),             shares (the “Shares”) of common stock, $0.0001 par value, of the Company (“Common Stock”), at a purchase price
of $            per share. The aggregate purchase price for the Shares shall be paid by the Participant by check payable to the order of the Company or such other method as may be
acceptable to the Company. Upon receipt by the Company of payment for the Shares, the Company shall issue to the Participant one or more certificates in the name of the Participant for that number of Shares purchased by the Participant. The
Participant agrees that the Shares shall be subject to the purchase options set forth in Sections 2 and 5 of this Agreement and the restrictions on transfer set forth in Section 4 of this Agreement. 

2. Purchase Option. 
 (a) In the event that the Participant ceases to be employed by the Company for any reason or no reason, with or without cause, prior to
            , the Company shall have the right and option (the “Purchase Option”) to purchase from the Participant, for a sum of
$            per share (the “Option Price”), some or all of the Unvested Shares (as defined below). 
 “Unvested Shares” means the total number of Shares multiplied by the Applicable Percentage at the time the Purchase Option becomes exercisable by the Company. The “Applicable
Percentage” shall be (i) 100% during the 12-month period ending             , (ii) [75]% less [2.083]% for each [month] of employment completed by the Participant with the
Company from and after             , and (iii) zero on or after             . 

(b) If the Participant is employed by a parent or subsidiary of the Company, any references in this Agreement to employment with the
Company or termination of employment by or with the Company shall instead be deemed to refer to such parent or subsidiary. 
 3.
Exercise of Purchase Option and Closing. 
 (a) The Company may exercise the Purchase Option by delivering or mailing to
the Participant (or his estate), within 90 days after the termination of the employment of the Participant with the Company, a written notice of exercise of the Purchase Option. Such notice 

 
shall specify the number of Shares to be purchased. If and to the extent the Purchase Option is not so exercised by the giving of such a notice within such 90-day period, the Purchase Option
shall automatically expire and terminate effective upon the expiration of such 90-day period. 
 (b) Within 10 days after
delivery to the Participant of the Company’s notice of the exercise of the Purchase Option pursuant to subsection (a) above, the Participant (or his estate) shall, pursuant to the provisions of the Joint Escrow Instructions referred to in
Section 7 below, tender to the Company at its principal offices the certificate or certificates representing the Shares which the Company has elected to purchase in accordance with the terms of this Agreement, duly endorsed in blank or with
duly endorsed stock powers attached thereto, all in form suitable for the transfer of such Shares to the Company. Promptly following its receipt of such certificate or certificates, the Company shall pay to the Participant the aggregate Option Price
for such Shares (provided that any delay in making such payment shall not invalidate the Company’s exercise of the Purchase Option with respect to such Shares). 
 (c) After the time at which any Shares are required to be delivered to the Company for transfer to the Company pursuant to subsection (b) above, the Company shall not pay any dividend to the
Participant on account of such Shares or permit the Participant to exercise any of the privileges or rights of a stockholder with respect to such Shares, but shall, in so far as permitted by law, treat the Company as the owner of such Shares.

 (d) The Option Price may be payable, at the option of the Company, in cancellation of all or a portion of any outstanding
indebtedness of the Participant to the Company or in cash (by check) or both. 
 (e) The Company shall not purchase any fraction
of a Share upon exercise of the Purchase Option, and any fraction of a Share resulting from a computation made pursuant to Section 2 of this Agreement shall be rounded to the nearest whole Share (with any one-half Share being rounded upward).

 (f) The Company may assign its Purchase Option to one or more persons or entities. 

4. Restrictions on Transfer. 
 (a) The Participant shall not sell, assign, transfer, pledge, hypothecate or otherwise dispose of, by operation of law or otherwise (collectively “transfer”) any Shares, or any interest therein,
that are subject to the Purchase Option, except that the Participant may transfer such Shares (i) to or for the benefit of any spouse, children, parents, uncles, aunts, siblings, grandchildren and any other relatives approved by the Board of
Directors (collectively, “Approved Relatives”) or to a trust established solely for the benefit of the Participant and/or Approved Relatives, provided that such Shares shall remain subject to this Agreement (including without
limitation the restrictions on transfer set forth in this Section 4, the Purchase Option and the right of first refusal set forth in Section 5) and such permitted transferee shall, as a condition to such transfer, deliver to the Company a
written instrument confirming that such transferee shall be bound by all of the terms and conditions of this Agreement or (ii) as part of the sale of all or substantially all of the shares of capital stock of the Company (including pursuant to
a merger or consolidation), provided that, in accordance with the Plan, the securities or other property received by the Participant in connection with such transaction shall remain subject to this Agreement. 

  
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 (b) The Participant shall not transfer any Shares, or any interest therein, that are no
longer subject to the Purchase Option, except in accordance with Section 5 below. 
 5. Right of First Refusal.

 (a) If the Participant proposes to transfer any Shares that are no longer subject to the Purchase Option (either because they
are no longer Unvested Shares or because the Purchase Option expired unexercised), then the Participant shall first give written notice of the proposed transfer (the “Transfer Notice”) to the Company. The Transfer Notice shall name the
proposed transferee and state the number of such Shares the Participant proposes to transfer (the “Offered Shares”), the price per share and all other material terms and conditions of the transfer. 

(b) For 30 days following its receipt of such Transfer Notice, the Company shall have the option to purchase all or part of the Offered
Shares at the price and upon the terms set forth in the Transfer Notice. In the event the Company elects to purchase all or part of the Offered Shares, it shall give written notice of such election to the Participant within such 30-day period.
Within 10 days after his or her receipt of such notice, the Participant shall tender to the Company at its principal offices the certificate or certificates representing the Offered Shares to be purchased by the Company, duly endorsed in blank by
the Participant or with duly endorsed stock powers attached thereto, all in a form suitable for transfer of the Offered Shares to the Company. Promptly following receipt of such certificate or certificates, the Company shall deliver or mail to the
Participant a check in payment of the purchase price for such Offered Shares; provided that if the terms of payment set forth in the Transfer Notice were other than cash against delivery, the Company may pay for the Offered Shares on
the same terms and conditions as were set forth in the Transfer Notice; and provided further that any delay in making such payment shall not invalidate the Company’s exercise of its option to purchase the Offered Shares. 

(c) If the Company does not elect to acquire all of the Offered Shares, the Participant may, within the 30-day period following the
expiration of the option granted to the Company under subsection (b) above, transfer the Offered Shares which the Company has not elected to acquire to the proposed transferee, provided that such transfer shall not be on terms and
conditions more favorable to the transferee than those contained in the Transfer Notice. Notwithstanding any of the above, all Offered Shares transferred pursuant to this Section 5 shall remain subject to this Agreement (including without
limitation the restrictions on transfer set forth in Section 4 and the right of first refusal set forth in this Section 5) and such transferee shall, as a condition to such transfer, deliver to the Company a written instrument confirming
that such transferee shall be bound by all of the terms and conditions of this Agreement. 
 (d) After the time at which the
Offered Shares are required to be delivered to the Company for transfer to the Company pursuant to subsection (b) above, the Company shall not pay any dividend to the Participant on account of such Offered Shares or permit the Participant to
exercise any of the privileges or rights of a stockholder with respect to such Offered Shares, but shall, insofar as permitted by law, treat the Company as the owner of such Offered Shares. 

  
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 (e) The following transactions shall be exempt from the provisions of this Section 5:

 (1) a transfer of Shares to or for the benefit of any Approved Relatives, or to a trust established solely for the benefit of
the Participant and/or Approved Relatives; 
 (2) any transfer pursuant to an effective registration statement filed by the
Company under the Securities Act of 1933, as amended (the “Securities Act”); and 
 (3) the sale of all or
substantially all of the outstanding shares of capital stock of the Company (including pursuant to a merger or consolidation); 

provided, however, that in the case of a transfer pursuant to clause (1) above, such Shares shall remain subject to this Agreement (including
without limitation the restrictions on transfer set forth in Section 4 and the right of first refusal set forth in this Section 5) and such transferee shall, as a condition to such transfer, deliver to the Company a written instrument
confirming that such transferee shall be bound by all of the terms and conditions of this Agreement. 
 (f) The Company may
assign its rights to purchase Offered Shares in any particular transaction under this Section 5 to one or more persons or entities. 
 (g) The provisions of this Section 5 shall terminate upon the earlier of the following events: 
 (1) the closing of the sale of shares of Common Stock in an underwritten public offering pursuant to an effective registration statement filed by the Company under the Securities Act; or 

(2) the sale of all or substantially all of the outstanding shares of capital stock, assets or business of the Company, by merger,
consolidation, sale of assets or otherwise (other than a merger or consolidation in which all or substantially all of the individuals and entities who were beneficial owners of the Company’s voting securities immediately prior to such
transaction beneficially own, directly or indirectly, more than 75% (determined on an as-converted basis) of the outstanding securities entitled to vote generally in the election of directors of the resulting, surviving or acquiring corporation in
such transaction). 
 (h) The Company shall not be required (1) to transfer on its books any of the Shares which shall have
been sold or transferred in violation of any of the provisions set forth in this Agreement, or (2) to treat as owner of such Shares or to pay dividends to any transferee to whom any such Shares shall have been so sold or transferred.

  
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 6. Agreement in Connection with Initial Public Offering. 

The Participant agrees, in connection with the initial underwritten public offering of the Common Stock pursuant to a registration
statement under the Securities Act, (i) not to (a) offer, pledge, announce the intention to sell, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant
to purchase, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for shares of Common Stock or (b) enter into any swap or other agreement that
transfers, in whole or in part, any of the economic consequences of ownership of shares of Common Stock, whether any transaction described in clause (a) or (b) is to be settled by delivery of shares of Common Stock or other securities, in
cash or otherwise, during the period beginning on the date of the filing of such registration statement with the Securities and Exchange Commission and ending 180 days from the date of the final prospectus relating to the offering (plus up to an
additional 34 days to the extent requested by the managing underwriters for such offering in order to address Rule 2711(f) of the National Association of Securities Dealers, Inc. or any similar successor provision), and (ii) to execute any
agreement reflecting clause (i) above as may be requested by the Company or the managing underwriters at the time of such offering. The Company may impose stop-transfer instructions with respect to the shares of Common Stock or other securities
subject to the foregoing restriction until the end of the “lock-up” period. 
 7. Escrow. 

The Participant shall, upon the execution of this Agreement, execute Joint Escrow Instructions in the form attached to this Agreement as
Exhibit A. The Joint Escrow Instructions shall be delivered to the Secretary of the Company, as escrow agent thereunder. The Participant shall deliver to such escrow agent a stock assignment duly endorsed in blank, in the form attached to
this Agreement as Exhibit B, and hereby instructs the Company to deliver to such escrow agent, on behalf of the Participant, the certificate(s) evidencing the Shares issued hereunder. Such materials shall be held by such escrow agent pursuant
to the terms of such Joint Escrow Instructions. 
 8. Restrictive Legends. 

All certificates representing Shares shall have affixed thereto legends in substantially the following form, in addition to any other
legends that may be required under federal or state securities laws: 
 “The shares of stock represented by this certificate
are subject to restrictions on transfer and an option to purchase set forth in a certain Restricted Stock Agreement between the corporation and the registered owner of these shares (or his predecessor in interest), and such Agreement is available
for inspection without charge at the office of the Secretary of the corporation.” 
 “The shares represented by this
certificate have not been registered under the Securities Act of 1933, as amended, and may not be sold, transferred or otherwise disposed of in the absence of an effective registration statement under such Act or an opinion of counsel satisfactory
to the corporation to the effect that such registration is not required.” 

  
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 9. Provisions of the Plan. 

(a) This Agreement is subject to the provisions of the Plan, a copy of which is furnished to the Participant with this Agreement.

 (b) As provided in the Plan, upon the occurrence of a Reorganization Event (as defined in the Plan), the repurchase and other
rights of the Company hereunder shall inure to the benefit of the Company’s successor and shall apply to the cash, securities or other property which the Shares were converted into or exchanged for pursuant to such Reorganization Event in the
same manner and to the same extent as they applied to the Shares under this Agreement. If, in connection with a Reorganization Event, a portion of the cash, securities and/or other property received upon the conversion or exchange of the Shares is
to be placed into escrow to secure indemnification or similar obligations, the mix between the vested and unvested portion of such cash, securities and/or other property that is placed into escrow shall be the same as the mix between the vested and
unvested portion of such cash, securities and/or other property that is not subject to escrow. 
 10. Investment
Representations. 
 The Participant represents, warrants and covenants as follows: 

(a) The Participant is purchasing the Shares for his own account for investment only, and not with a view to, or for sale in connection
with, any distribution of the Shares in violation of the Securities Act, or any rule or regulation under the Securities Act. 

(b) The Participant has had such opportunity as he has deemed adequate to obtain from representatives of the Company such information as
is necessary to permit him to evaluate the merits and risks of his investment in the Company. 
 (c) The Participant has
sufficient experience in business, financial and investment matters to be able to evaluate the risks involved in the purchase of the Shares and to make an informed investment decision with respect to such purchase. 

(d) The Participant can afford a complete loss of the value of the Shares and is able to bear the economic risk of holding such Shares
for an indefinite period. 
 (e) The Participant understands that (i) the Shares have not been registered under the
Securities Act and are “restricted securities” within the meaning of Rule 144 under the Securities Act; (ii) the Shares cannot be sold, transferred or otherwise disposed of unless they are subsequently registered under the
Securities Act or an exemption from registration is then available; (iii) in any event, the exemption from registration under Rule 144 will not be available for at least one year and even then will not be available unless a public market
then exists for the Common Stock, adequate information concerning the Company is then available to the public, and other terms and conditions of Rule 144 are complied with; and (iv) there is now no registration statement on file with the
Securities and Exchange Commission with respect to any stock of the Company and the Company has no obligation or current intention to register the Shares under the Securities Act. 

  
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 11. Withholding Taxes; Section 83(b) Election. 

(a) The Participant acknowledges and agrees that the Company has the right to deduct from payments of any kind otherwise due to the
Participant any federal, state or local taxes of any kind required by law to be withheld with respect to the purchase of the Shares by the Participant or the lapse of the Purchase Option. 

(b) The Participant has reviewed with the Participant’s own tax advisors the federal, state, local and foreign tax consequences of
this investment and the transactions contemplated by this Agreement. The Participant is relying solely on such advisors and not on any statements or representations of the Company or any of its agents. The Participant understands that the
Participant (and not the Company) shall be responsible for the Participant’s own tax liability that may arise as a result of this investment or the transactions contemplated by this Agreement. The Participant understands that it may be
beneficial in many circumstances to elect to be taxed at the time the Shares are purchased rather than when and as the Company’s Purchase Option expires by filing an election under Section 83(b) of the Internal Revenue Code of 1986 with
the I.R.S. within 30 days from the date of purchase. 
 THE PARTICIPANT ACKNOWLEDGES THAT IT IS SOLELY THE PARTICIPANT’S
RESPONSIBILITY AND NOT THE COMPANY’S TO FILE TIMELY THE ELECTION UNDER SECTION 83(b), EVEN IF THE PARTICIPANT REQUESTS THE COMPANY OR ITS REPRESENTATIVES TO MAKE THIS FILING ON THE PARTICIPANT’S BEHALF. 

12. Miscellaneous. 
 (a) No Rights to Employment. The Participant acknowledges and agrees that the vesting of the Shares pursuant to Section 2 hereof is earned only by continuing service as an employee at the will
of the Company (not through the act of being hired or purchasing shares hereunder). The Participant further acknowledges and agrees that the transactions contemplated hereunder and the vesting schedule set forth herein do not constitute an express
or implied promise of continued engagement as an employee or consultant for the vesting period, for any period, or at all. 

(b) Severability. The invalidity or unenforceability of any provision of this Agreement shall not affect the validity or
enforceability of any other provision of this Agreement, and each other provision of this Agreement shall be severable and enforceable to the extent permitted by law. 
 (c) Waiver. Any provision for the benefit of the Company contained in this Agreement may be waived, either generally or in any particular instance, by the Board of Directors of the Company.

 (d) Binding Effect. This Agreement shall be binding upon and inure to the benefit of the Company and the Participant
and their respective heirs, executors, administrators, legal representatives, successors and assigns, subject to the restrictions on transfer set forth in Sections 4 and 5 of this Agreement. 

  
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 (e) Notice. All notices required or permitted hereunder shall be in writing and
deemed effectively given upon personal delivery or five days after deposit in the United States Post Office, by registered or certified mail, postage prepaid, addressed to the other party hereto at the address shown beneath his or its respective
signature to this Agreement, or at such other address or addresses as either party shall designate to the other in accordance with this Section 12(e). 
 (f) Pronouns. Whenever the context may require, any pronouns used in this Agreement shall include the corresponding masculine, feminine or neuter forms, and the singular form of nouns and pronouns
shall include the plural, and vice versa. 
 (g) Entire Agreement. This Agreement and the Plan constitute the entire
agreement between the parties, and supersedes all prior agreements and understandings, relating to the subject matter of this Agreement. 
 (h) Amendment. This Agreement may be amended or modified only by a written instrument executed by both the Company and the Participant. 

(i) Governing Law. This Agreement shall be construed, interpreted and enforced in accordance with the internal laws of the State
of Delaware without regard to any applicable conflicts of laws. 
 (j) Participant’s Acknowledgments. The
Participant acknowledges that he or she: (i) has read this Agreement; (ii) has been represented in the preparation, negotiation, and execution of this Agreement by legal counsel of the Participant’s own choice or has voluntarily
declined to seek such counsel; (iii) understands the terms and consequences of this Agreement; (iv) is fully aware of the legal and binding effect of this Agreement; and (v) understands that the law firm of WilmerHale, is acting as
counsel to the Company in connection with the transactions contemplated by the Agreement, and is not acting as counsel for the Participant. 

  
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 IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the day and year
first above written. 
  

					
	 EPIZYME, INC.

		
	By:	 	 
		 	Title:	 	 
	Address:	 	 
		 		 	 
	
	 
	[Name of Participant]
		
	Address:	 	 
		 		 	 

  
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 Exhibit A 
 EpiZyme, Inc. 
 Joint Escrow Instructions 

                    
    ,              
 Secretary 

EpiZyme, Inc. 
 325 Vassar Street, Suite 2B

 Cambridge, MA 02139 
 Dear Sir:

 As Escrow Agent for EpiZyme, Inc., a Delaware corporation, and its successors in interest under the Restricted Stock Agreement
(the “Agreement”) of even date herewith, to which a copy of these Joint Escrow Instructions is attached (the “Company”), and the undersigned person (“Holder”), you are hereby authorized and directed to hold the
documents delivered to you pursuant to the terms of the Agreement in accordance with the following instructions: 
 1.
Appointment. Holder irrevocably authorizes the Company to deposit with you any certificates evidencing Shares (as defined in the Agreement) to be held by you hereunder and any additions and substitutions to said Shares. For purposes of these
Joint Escrow Instructions, “Shares” shall be deemed to include any additional or substitute property. Holder does hereby irrevocably constitute and appoint you as his attorney-in-fact and agent for the term of this escrow to execute with
respect to such Shares all documents necessary or appropriate to make such Shares negotiable and to complete any transaction herein contemplated. Subject to the provisions of this Section 1 and the terms of the Agreement, Holder shall exercise
all rights and privileges of a stockholder of the Company while the Shares are held by you. 
 2. Closing of Purchase.

 (a) Upon any purchase by the Company of the Shares pursuant to the Agreement, the Company shall give to Holder and you a
written notice specifying the number of Shares to be purchased, the purchase price for the Shares, as determined pursuant to the Agreement, and the time for a closing hereunder (the “Closing”) at the principal office of the Company. Holder
and the Company hereby irrevocably authorize and direct you to close the transaction contemplated by such notice in accordance with the terms of said notice. 
 (b) At the Closing, you are directed (i) to date the stock assignment form or forms necessary for the transfer of the Shares, (ii) to fill in on such form or forms the number of Shares being
transferred, and (iii) to deliver the same, together with the certificate or certificates evidencing the Shares to be transferred, to the Company against the simultaneous delivery to you of the purchase price for the Shares being purchased
pursuant to the Agreement. 

  
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 3. Withdrawal. The Holder shall have the right to withdraw from this escrow any
Shares as to which the Purchase Option (as defined in the Agreement) has terminated or expired. 
 4. Duties of Escrow
Agent. 
 (a) Your duties hereunder may be altered, amended, modified or revoked only by a writing signed by all of the
parties hereto. 
 (b) You shall be obligated only for the performance of such duties as are specifically set forth herein and
may rely and shall be protected in relying or refraining from acting on any instrument reasonably believed by you to be genuine and to have been signed or presented by the proper party or parties. You shall not be personally liable for any act you
may do or omit to do hereunder as Escrow Agent or as attorney-in-fact of Holder while acting in good faith and in the exercise of your own good judgment, and any act done or omitted by you pursuant to the advice of your own attorneys shall be
conclusive evidence of such good faith. 
 (c) You are hereby expressly authorized to disregard any and all warnings given by
any of the parties hereto or by any other person or entity, excepting only orders or process of courts of law, and are hereby expressly authorized to comply with and obey orders, judgments or decrees of any court. If you are uncertain of any actions
to be taken or instructions to be followed, you may refuse to act in the absence of an order, judgment or decrees of a court. In case you obey or comply with any such order, judgment or decree of any court, you shall not be liable to any of the
parties hereto or to any other person or entity, by reason of such compliance, notwithstanding any such order, judgment or decree being subsequently reversed, modified, annulled, set aside, vacated or found to have been entered without jurisdiction.

 (d) You shall not be liable in any respect on account of the identity, authority or rights of the parties executing or
delivering or purporting to execute or deliver the Agreement or any documents or papers deposited or called for hereunder. 

(e) You shall be entitled to employ such legal counsel and other experts as you may deem necessary properly to advise you in connection
with your obligations hereunder and may rely upon the advice of such counsel. 
 (f) Your rights and responsibilities as Escrow
Agent hereunder shall terminate if (i) you cease to be Secretary of the Company or (ii) you resign by written notice to each party. In the event of a termination under clause (i), your successor as Secretary shall become Escrow Agent
hereunder; in the event of a termination under clause (ii), the Company shall appoint a successor Escrow Agent hereunder. 

(g) If you reasonably require other or further instruments in connection with these Joint Escrow Instructions or obligations in respect
hereto, the necessary parties hereto shall join in furnishing such instruments. 

  
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 (h) It is understood and agreed that if you believe a dispute has arisen with respect to the
delivery and/or ownership or right of possession of the securities held by you hereunder, you are authorized and directed to retain in your possession without liability to anyone all or any part of said securities until such dispute shall have been
settled either by mutual written agreement of the parties concerned or by a final order, decree or judgment of a court of competent jurisdiction after the time for appeal has expired and no appeal has been perfected, but you shall be under no duty
whatsoever to institute or defend any such proceedings. 
 (i) These Joint Escrow Instructions set forth your sole duties with
respect to any and all matters pertinent hereto and no implied duties or obligations shall be read into these Joint Escrow Instructions against you. 
 (j) The Company shall indemnify you and hold you harmless against any and all damages, losses, liabilities, costs, and expenses, including attorneys’ fees and disbursements, (including without
limitation the fees of counsel retained pursuant to Section 4(e) above, for anything done or omitted to be done by you as Escrow Agent in connection with this Agreement or the performance of your duties hereunder, except such as shall result
from your gross negligence or willful misconduct. 
 5. Notice. Any notice required or permitted hereunder shall be given
in writing and shall be deemed effectively given upon personal delivery or upon deposit in the United States Post Office, by registered or certified mail with postage and fees prepaid, addressed to each of the other parties thereunto entitled at the
following addresses, or at such other addresses as a party may designate by ten days’ advance written notice to each of the other parties hereto. 
  

					
	 COMPANY:
	  	Notices to the Company shall be sent to the address set forth in the salutation hereto, Attn: President	  	
			
	 HOLDER:
	  	Notices to Holder shall be sent to the address set forth below Holder’s signature below.	  	
			
	 ESCROW AGENT:    
	  	Notices to the Escrow Agent shall be sent to the address set forth in the salutation hereto.	  	

 6. Miscellaneous. 
 (a) By signing these Joint Escrow Instructions, you become a party hereto only for the purpose of said Joint Escrow Instructions, and you do not become a party to the Agreement. 

(b) This instrument shall be binding upon and inure to the benefit of the parties hereto and their respective successors and permitted
assigns. 

  
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	 Very truly yours,
  

EpiZyme, Inc.

		
	By:	 	 
	Title:	 	 
	
	 HOLDER:
  

	(Signature)
	
	 
	Print Name
		
	Address:	 	 
		
		 	 
		
	Date Signed:	 	 

 ESCROW AGENT:              

 
  

  
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 Exhibit B 

(STOCK ASSIGNMENT SEPARATE FROM CERTIFICATE) 
 FOR VALUE RECEIVED, I hereby sell, assign and transfer unto
            (            ) shares of Common Stock, $0.0001 par value per share, of EpiZyme, Inc. (the “Corporation”)
standing in my name on the books of the Corporation represented by Certificate(s) Number             herewith, and do hereby irrevocably constitute and appoint
            attorney to transfer the said stock on the books of the Corporation with full power of substitution in the premises. 

 

							
				
		 		 	Dated:	 	 
				
	IN PRESENCE OF	 		 		 	 
				
		 		 		 	 

 NOTICE: The signature(s) to this assignment must correspond with the name as written upon the face of the
certificate, in every particular, without alteration, enlargement, or any change whatever and must be guaranteed by a commercial bank, trust company or member firm of the Boston, New York or Midwest Stock Exchange. 

  
 - 14 -EX-10.11

 Exhibit 10.11 
 Confidential Materials omitted and filed separately with the Securities and Exchange Commission. Double asterisks denote omissions. 
 EXECUTION VERSION 
 COLLABORATION AND LICENSE AGREEMENT

 by and between 
 GLAXO GROUP LIMITED 
 and 

EPIZYME, INC. 
 CONFIDENTIAL 

 Table of Contents 

 

									
	 	 	 	 	 	  	Page	 
		
	 ARTICLE 1 DEFINITIONS
	  	 	1	  
				
		 	 1.1
	 	 “Affiliate”
	  	 	1	  
		 	 1.2
	 	 “Annual Net Sales”
	  	 	2	  
		 	 1.3
	 	 “Available Target”
	  	 	2	  
		 	 1.4
	 	 “Business Day”
	  	 	2	  
		 	 1.5
	 	 “Calendar Quarter”
	  	 	2	  
		 	 1.6
	 	 “Calendar Year”
	  	 	2	  
		 	 1.7
	 	 “cGMP”
	  	 	2	  
		 	 1.8
	 	 “Change of Control Event”
	  	 	2	  
		 	 1.9
	 	 “Clinical Trial”
	  	 	2	  
		 	 1.10
	 	 “Collaboration IP”
	  	 	2	  
		 	 1.11
	 	 “Collaboration Know-How”
	  	 	2	  
		 	 1.12
	 	 “Collaboration Patents”
	  	 	2	  
		 	 1.13
	 	 “Commercialization” and “Commercialize”
	  	 	3	  
		 	 1.14
	 	 “Commercially Reasonable Efforts”
	  	 	3	  
		 	 1.15
	 	 “Comparable Third Party Product”
	  	 	3	  
		 	 1.16
	 	 “Comparable Third Party Product Competition”
	  	 	4	  
		 	 1.17
	 	 “Compound(s)”
	  	 	4	  
		 	 1.18
	 	 “Control”, “Controls” or “Controlled”
	  	 	4	  
		 	 1.19
	 	 “Cover”, “Covering” or “Covered”
	  	 	4	  
		 	 1.20
	 	 “Develop” or “Development”
	  	 	4	  
		 	 1.21
	 	 “Development Candidate”
	  	 	5	  
		 	 1.22
	 	 “Development Candidate Selection Criteria”
	  	 	5	  
		 	 1.23
	 	 “Diagnostic IP”
	  	 	5	  
		 	 1.24
	 	 “Diagnostic Know-How”
	  	 	5	  
		 	 1.25
	 	 “Diagnostic Patents”
	  	 	5	  
		 	 1.26
	 	 “Diagnostic Product”
	  	 	5	  
		 	 1.27
	 	 “Dollars” or “$”
	  	 	5	  
		 	 1.28
	 	 “Eligible Dropped Target”
	  	 	5	  
		 	 1.29
	 	 “EMA”
	  	 	5	  
		 	 1.30
	 	 “EPIZYME Blocked Targets”
	  	 	5	  
		 	 1.31
	 	 “EPIZYME Compound”
	  	 	5	  
		 	 1.32
	 	 “EPIZYME Diagnostic IP”
	  	 	5	  
		 	 1.33
	 	 “EPIZYME Diagnostic Know-How”
	  	 	5	  
		 	 1.34
	 	 “EPIZYME Diagnostic Patents”
	  	 	6	  
		 	 1.35
	 	 “EPIZYME Diagnostic Product”
	  	 	6	  
		 	 1.36
	 	 “EPIZYME IP”
	  	 	6	  
		 	 1.37
	 	 “EPIZYME Know-How”
	  	 	6	  
		 	 1.38
	 	 “EPIZYME Patents”
	  	 	6	  
		 	 1.39
	 	 “EPIZYME Product”
	  	 	7	  

  
 - i -

									
		 	1.40	 	 “EU”
	  	 	7	  
		 	1.41	 	 “European Commission”
	  	 	7	  
		 	1.42	 	 “Executive Officers”
	  	 	7	  
		 	1.43	 	 “FDA”
	  	 	7	  
		 	1.44	 	 “Field”
	  	 	7	  
		 	1.45	 	 “First Commercial Sale”
	  	 	7	  
		 	1.46	 	 “FTE”
	  	 	8	  
		 	1.47	 	 “FTE Cost”
	  	 	8	  
		 	1.48	 	 “FTE Rate”
	  	 	8	  
		 	1.49	 	 “GLP Toxicology Study”
	  	 	8	  
		 	1.50	 	 “GSK IP”
	  	 	8	  
		 	1.51	 	 “GSK Know-How”
	  	 	8	  
		 	1.52	 	 “GSK Patent(s)”
	  	 	8	  
		 	1.53	 	 “IND”
	  	 	9	  
		 	1.54	 	 “Indication”
	  	 	9	  
		 	1.55	 	 “Initiation”
	  	 	9	  
		 	1.56	 	 “Joint IP”
	  	 	9	  
		 	1.57	 	 “Joint Know-How”
	  	 	9	  
		 	1.58	 	 “Joint Patents”
	  	 	9	  
		 	1.59	 	 “Know-How”
	  	 	9	  
		 	1.60	 	 “Law” or “Laws”
	  	 	9	  
		 	1.61	 	 “Lead Candidate”
	  	 	9	  
		 	1.62	 	 “Lead Candidate Criteria”
	  	 	10	  
		 	1.63	 	 “Licensed Compound(s)”
	  	 	10	  
		 	1.64	 	 “Licensed Product(s)”
	  	 	10	  
		 	1.65	 	 “MAA”
	  	 	10	  
		 	1.66	 	 “Major EU Country”
	  	 	10	  
		 	1.67	 	 “Major Market Country(ies)”
	  	 	10	  
		 	1.68	 	 “MHLW”
	  	 	10	  
		 	1.69	 	 “NDA”
	  	 	10	  
		 	1.70	 	 “Net Sales”
	  	 	10	  
		 	1.71	 	 “Out-of-Pocket Costs”
	  	 	13	  
		 	1.72	 	 “Patent”
	  	 	13	  
		 	1.73	 	 “Patent-Based Exclusivity”
	  	 	13	  
		 	1.74	 	 “Person”
	  	 	13	  
		 	1.75	 	 “Phase 1 Clinical Trial”
	  	 	13	  
		 	1.76	 	 “Phase 2 Clinical Trial”
	  	 	13	  
		 	1.77	 	 “Phase 3 Clinical Trial”
	  	 	14	  
		 	1.78	 	 “Prosecution and Maintenance” or “Prosecute and Maintain”
	  	 	14	  
		 	1.79	 	 “Regulatory Approval”
	  	 	14	  
		 	1.80	 	 “Regulatory Authority”
	  	 	14	  
		 	1.81	 	 “Regulatory Materials”
	  	 	14	  
		 	1.82	 	 “Research Plan”
	  	 	14	  
		 	1.83	 	 “Selection Term”
	  	 	14	  
		 	1.84	 	 “Sublicensee”
	  	 	15	  
		 	1.85	 	 “Target”
	  	 	15	  

  
 - ii -

									
		 	1.86	 	 “Target Validation”
	  	 	15	  
		 	1.87	 	 “Territory”
	  	 	15	  
		 	1.88	 	 “Third Party”
	  	 	15	  
		 	1.89	 	 “Tractable Hit”
	  	 	15	  
		 	1.90	 	 “Tractable Hit Criteria”
	  	 	15	  
		 	1.91	 	 “United States” or “U.S.”
	  	 	15	  
		 	1.92	 	 “Valid Claim”
	  	 	15	  
		 	1.93	 	 Additional Definitions
	  	 	16	  
		
	 ARTICLE 2 TARGET SELECTION; COLLABORATION ACTIVITIES
	  	 	17	  
				
		 	2.1	 	 Collaboration Overview
	  	 	17	  
		 	2.2	 	 Targets
	  	 	18	  
		 	2.3	 	 Research Term; Research Plan; Research Activities
	  	 	20	  
		 	2.4	 	 Tractable Hits; Lead Candidates; Development Candidates
	  	 	21	  
		 	2.5	 	 Reports; Results
	  	 	22	  
		 	2.6	 	 Subcontracting
	  	 	22	  
		 	2.6.1	 		  			
		 	2.7	 	 Regulatory Matters; Compliance
	  	 	23	  
		
	 ARTICLE 3 POST-RESEARCH TERM ACTIVITIES; GSK DILIGENCE
	  	 	25	  
				
		 	3.1	 	 Development and Commercialization
	  	 	25	  
		 	3.2	 	 Diligence
	  	 	26	  
		 	3.3	 	 Reports
	  	 	26	  
		
	 ARTICLE 4 GOVERNANCE
	  	 	26	  
				
		 	4.1	 	 Joint Steering Committee
	  	 	26	  
		 	4.2	 	 Subcommittee(s)
	  	 	29	  
		 	4.3	 	 Joint Project Team
	  	 	29	  
		 	4.4	 	 Patent Liaisons
	  	 	30	  
		 	4.5	 	 Alliance Managers
	  	 	30	  
		
	 ARTICLE 5 LICENSE GRANTS
	  	 	30	  
				
		 	5.1	 	 License Grants To GSK
	  	 	30	  
		 	5.2	 	 License Grants to EPIZYME
	  	 	31	  
		 	5.3	 	 Rights Retained by the Parties
	  	 	32	  
		 	5.4	 	 Section 365(n) of the Bankruptcy Code
	  	 	32	  
		 	5.5	 	 Technical Transfer and Disclosure of Know-How
	  	 	32	  
		
	 ARTICLE 6 FINANCIAL TERMS; EQUITY OPTION
	  	 	33	  
				
		 	6.1	 	 Upfront Fee
	  	 	33	  
		 	6.2	 	 Research Funding
	  	 	33	  
		 	6.3	 	 Equity Option
	  	 	34	  

  
 - iii -

									
		 	6.4	 	 Target Validation and Tractable Hit Milestone Payments
	  	 	35	  
		 	6.5	 	 Development Milestones
	  	 	35	  
		 	6.6	 	 Additional Milestone for Diagnostic Products
	  	 	36	  
		 	6.7	 	 Sales Milestones
	  	 	37	  
		 	6.8	 	 Licensed Product Royalties
	  	 	37	  
		 	6.9	 	 Royalties for EPIZYME Products
	  	 	39	  
		 	6.10	 	 Reports; Sales Milestones; Royalty Payments
	  	 	40	  
		 	6.11	 	 Methods of Payments
	  	 	40	  
		 	6.12	 	 Accounting
	  	 	41	  
		 	6.13	 	 Taxes
	  	 	41	  
		 	6.14	 	 Late Payments
	  	 	42	  
		
	 ARTICLE 7 EXCLUSIVITY
	  	 	43	  
				
		 	7.1	 	 Selected Target Exclusivity
	  	 	43	  
		
	 ARTICLE 8 OWNERSHIP OF INTELLECTUAL PROPERTY RIGHTS
	  	 	44	  
				
		 	8.1	 	 Ownership
	  	 	44	  
		 	8.2	 	 Prosecution and Maintenance of Patents
	  	 	45	  
		 	8.3	 	 Patent Costs
	  	 	47	  
		 	8.4	 	 Defense of Claims Brought by Third Parties
	  	 	47	  
		 	8.5	 	 Enforcement of EPIZYME Patents, EPIZYME Diagnostic Patents, Collaboration Patents and Joint Patents
	  	 	47	  
		
	 ARTICLE 9 CONFIDENTIALITY
	  	 	49	  
				
		 	9.1	 	 Confidentiality; Exceptions
	  	 	49	  
		 	9.2	 	 Authorized Disclosure
	  	 	50	  
		 	9.3	 	 Press Release; Disclosure of Agreement
	  	 	50	  
		 	9.4	 	 Prior Disclosures of Confidential Information
	  	 	52	  
		 	9.5	 	 Remedies
	  	 	52	  
		 	9.6	 	 Publications
	  	 	52	  
		 	9.7	 	 Clinical Trial Register
	  	 	54	  
		
	 ARTICLE 10 REPRESENTATIONS AND WARRANTIES
	  	 	54	  
				
		 	10.1	 	 Representations and Warranties of Both Parties
	  	 	54	  
		 	10.2	 	 Representations and Warranties of EPIZYME
	  	 	55	  
		 	10.3	 	 Mutual Covenants
	  	 	55	  
		 	10.4	 	 Disclaimer
	  	 	56	  
		
	 ARTICLE 11 INDEMNIFICATION; INSURANCE
	  	 	56	  
				
		 	11.1	 	 Indemnification by GSK
	  	 	56	  
		 	11.2	 	 Indemnification by EPIZYME
	  	 	57	  
		 	11.3	 	 Procedure
	  	 	57	  

  
 - iv -

							
		 	11.4	 	 Insurance
	  	58
		 	11.5	 	 LIMITATION OF LIABILITY
	  	59
		
	ARTICLE 12 TERM AND TERMINATION	  	59
				
		 	12.1	 	 Term; Expiration
	  	59
		 	12.2	 	 Unilateral Termination by GSK
	  	60
		 	12.3	 	 Termination for Cause
	  	60
		 	12.4	 	 Termination for Patent Challenges
	  	61
		 	12.5	 	 Effects of Termination
	  	62
		 	12.6	 	 Accrued Rights; Surviving Provisions
	  	67
		
	ARTICLE 13 MISCELLANEOUS	  	68
				
		 	13.1	 	 Dispute Resolution
	  	68
		 	13.2	 	 Arbitration Request
	  	68
		 	13.3	 	 Governing Law
	  	69
		 	13.4	 	 Assignment
	  	70
		 	13.5	 	 Performance Warranty
	  	70
		 	13.6	 	 Force Majeure
	  	70
		 	13.7	 	 Notices
	  	71
		 	13.8	 	 Export Clause
	  	72
		 	13.9	 	 Waiver
	  	72
		 	13.10	 	 Severability
	  	72
		 	13.11	 	 Entire Agreement
	  	72
		 	13.12	 	 Independent Contractors
	  	72
		 	13.13	 	 Non-solicitation of Key Employees
	  	72
		 	13.14	 	 Headings; Construction; Interpretation
	  	73
		 	13.15	 	 Books and Records
	  	73
		 	13.16	 	 Further Actions
	  	73
		 	13.17	 	 Parties in Interest
	  	73
		 	13.18	 	 Performance by Affiliates
	  	73
		 	13.19	 	 Counterparts
	  	74

 List of Exhibits 
  

					
	Exhibit A	  	-	  	EPIZYME Blocked Targets
	Exhibit B	  	-	  	Initial Research Plan and Criteria
	Exhibit C	  	-	  	Policies
	Exhibit D	  	-	  	Key Employees

  
 - v -

 COLLABORATION AND LICENSE AGREEMENT 

This COLLABORATION AND LICENSE AGREEMENT (the “Agreement”) is entered into and made effective as of
the 8th day of January, 2011 (the “Effective
Date”) by and between Epizyme, Inc., a Delaware corporation having its principal place of business at 840 Memorial Drive, Cambridge, Massachusetts 02139, U.S.A. (“EPIZYME”), and Glaxo Group Limited, a company existing under
the laws of England, having its registered office at Glaxo Wellcome House, Berkeley Avenue, Greenford, Middlesex, UB6 0NN, England (“GSK”). EPIZYME and GSK are each referred to herein by name or as a “Party” or,
collectively, as the “Parties.” 
 RECITALS 

WHEREAS, EPIZYME possesses proprietary technology and intellectual property to identify and develop novel, small molecule histone
methyltransferase (“HMT”) inhibitors; 
 WHEREAS, GSK possesses expertise in the Development and
Commercialization (each as defined below) of human pharmaceuticals; 
 WHEREAS, GSK desires to engage in a collaborative effort
with EPIZYME pursuant to which the Parties will carry out research activities directed to up to three (3) Selected Targets at one time (each as defined below), with the goal of identifying compounds directed to such Selected Targets using
EPIZYME’s proprietary technology; and 
 WHEREAS, GSK desires to obtain exclusive rights from EPIZYME to Develop and
Commercialize such compounds directed to Selected Targets for any and all uses in the Territory (as defined below), all on the terms and conditions set forth herein. 
 NOW, THEREFORE, in consideration of the premises and mutual covenants herein contained, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the
Parties hereby agree as follows: 
 ARTICLE 1 
 DEFINITIONS 
 As used in this Agreement, the following terms will have the
meanings set forth in this Article 1 unless context dictates otherwise: 
 1.1 “Affiliate” means any Person
which, directly or indirectly through one (1) or more intermediaries, controls, is controlled by or is under common control with a Party to this Agreement, for so long as such control exists, regardless of whether such Affiliate is or becomes
an Affiliate on or after the Effective Date. A Person shall be deemed to “control” another Person if it: (a) owns, directly or indirectly, beneficially or legally, at least fifty percent (50%) of the outstanding voting securities
or capital stock (or such lesser percentage which is the maximum allowed to be owned by a Person in a particular jurisdiction) of such other Person, or has other comparable ownership interest with respect to any Person other than a corporation; or
(b) has the power, whether pursuant to contract, ownership of securities or otherwise, to direct the management and policies of the Person. 

 1.2 “Annual Net Sales” means total Net Sales in the Territory in a
particular Calendar Year. 
 1.3 “Available Target” means at any relevant time during the Selection Term,
Targets identified by EPIZYME or by GSK, other than (a) the then-current Selected Targets, (b) Dropped Targets, (c) Passed ROFO Targets that are not available for selection pursuant to Section 2.2.4, or (d) the EPIZYME
Blocked Targets. 
 1.4 “Business Day” means a day on which banking institutions in Boston, Massachusetts,
United States, and London, England are open for business, excluding any Saturday or Sunday and the nine (9) consecutive calendar days beginning on December 24th and continuing through January 1st of each Calendar Year during the Term.

 1.5 “Calendar Quarter” means a period of three (3) consecutive months ending on the last day of March,
June, September, or December, respectively. 
 1.6 “Calendar Year” means a period of twelve
(12) consecutive months beginning on January 1 and ending on December 31. 
 1.7 “cGMP” means
all applicable standards relating to manufacturing practices for fine chemicals, intermediates, bulk products and/or finished products, including (a) all applicable principles detailed in the FDA’s current Good Manufacturing Practices, 21
CFR Parts 210 and 211 and The Rules Governing Medicinal Products in the European Community, Volume IV, Good Manufacturing Practice for Medicinal Products, as each may be amended from time to time, and (b) all applicable Laws promulgated by any
governmental authority having jurisdiction over the manufacture of a Compound, Licensed Compound or Licensed Product, as applicable. 
 1.8 “Change of Control Event” means (a) EPIZYME merges or consolidates with any other entity (other than a wholly owned subsidiary of EPIZYME), (b) the sale, conveyance,
transfer or lease to a Third Party of all or substantially all of the assets of EPIZYME in one transaction or a series of related transactions, or (c) the acquisition of control (as defined in Section 1.1) of EPIZYME by any Third Party by
means of any transaction or series of related transactions to which EPIZYME is a party (including any stock acquisition, merger or consolidation). 
 1.9 “Clinical Trial” means a Phase 1 Clinical Trial, Phase 2 Clinical Trial, Phase 3 Clinical Trial, or a study incorporating more than one of these phases. 

1.10 “Collaboration IP” means Collaboration Know-How and Collaboration Patents. 

1.11 “Collaboration Know-How” means Know-How (other than Joint Know-How) that is discovered, developed, invented,
conceived or reduced to practice by or on behalf of either Party or its respective Affiliates or Sublicensees pursuant to the conduct of activities under the Collaboration. 
 1.12 “Collaboration Patents” means any Patents (other than the Joint Patents) that claim any Collaboration Know-How. 

  
 - 2 -

 1.13 “Commercialization” and “Commercialize” means all
activities undertaken relating to the marketing, promotion (including advertising, detailing, sponsored product or continuing medical education, and post-Regulatory Approval clinical studies), any other offering for sale, distribution and sale of a
product. 
 1.14 “Commercially Reasonable Efforts” means with respect to EPIZYME or GSK, such efforts that are
consistent with the efforts and resources then used by EPIZYME or GSK, as applicable, including taking into account any assignment permitted under Section 13.4, in the exercise of its commercially reasonable practices relating to the research,
Development, seeking Regulatory Approval and Commercialization of a similarly situated pharmaceutical product, as applicable to the rights, responsibilities and obligations of such Party under this Agreement where such similarly situated
pharmaceutical product: 
 (i) has scientific attributes similar to those of the relevant Compound, Licensed Compound or
Licensed Product; 
 (ii) is at a similar stage in its research, Development or commercial product life as the relevant
Compound, Licensed Compound or Licensed Product; 
 (iii) has commercial and market potential similar to the relevant Compound,
Licensed Compound or Licensed Product, taking into account issues of intellectual property scope, subject matter and coverage, safety and efficacy, product profile, competitiveness of the marketplace, proprietary position, regulatory exclusivity,
anticipated or approved labeling, present and future market potential, and profitability (including pricing and reimbursement status achieved or likely to be achieved); and 
 (iv) is solely owned by it or to which it has exclusive rights. 
 Commercially Reasonable Efforts
shall be determined on a market-by-market and Indication-by-Indication basis, and it is anticipated that the level of efforts required will be different for different markets and Indications, and may change over time, reflecting changes in the
status of a Compound, Licensed Compound or Licensed Product and the markets and other relevant factors involved. 
 1.15
“Comparable Third Party Product” means, with respect to a Licensed Product in any country in the Territory, any pharmaceutical product sold by a Third Party not authorized by or on behalf of GSK, its Affiliates or Sublicensees,
that: 
 (a) contains, as an active pharmaceutical ingredient, the same Compound as the Licensed Compound contained in the
applicable Licensed Product; and 
 (b) is approved by the applicable Regulatory Authority in such country for one or more of
the same Indications as the applicable Licensed Product. 
 To the extent the term “Comparable Third Party Product” is
used herein with respect to a Royalty-Bearing EPIZYME Product, such term shall have the meaning set forth herein, with all references to “GSK” replaced by “EPIZYME” and all references to “Licensed Product” replaced with
“Royalty-Bearing EPIZYME Product.” 

  
 - 3 -

 1.16 “Comparable Third Party Product Competition” means, with respect to a
Licensed Product in any country in the Territory in a given Calendar Quarter, that, during such Calendar Quarter: 
 (a) one or
more Comparable Third Party Product(s) is commercially available in such country; and 
 (b) such Comparable Third Party
Product(s) have a market share [**] percent ([**]%) or more of the aggregate market in such country of such Licensed Product and the Comparable Third Party Product(s) (based on sales of units of such Licensed Product and such Comparable Third Party
Product(s), as reported by IMS International, or if such data are not available, such other reliable data source as reasonably determined by GSK). 
 To the extent the term “Comparable Third Party Product Competition” is used herein with respect to a Royalty-Bearing EPIZYME Product, such term shall have the meaning set forth herein, with all
references to “GSK” replaced by “EPIZYME” and all references to “Licensed Product” replaced with “Royalty-Bearing EPIZYME Product.” 
 1.17 “Compound(s)” means a small molecule HMT inhibitor. 
 1.18
“Control”, “Controls” or “Controlled” means, with respect to any intellectual property, possession of the right (whether through ownership or license (other than by operation of this Agreement) or
control (as defined in Section 1.1) over an Affiliate with such right) to grant the licenses or sublicenses as provided herein without violating the terms of any then-existing agreement with any Third Party. 

1.19 “Cover”, “Covering” or “Covered” means, with respect to a product, composition,
technology, process or method that, in the absence of ownership of or a license granted under a Valid Claim, the manufacture, use, offer for sale, sale or importation of such product or composition, or the practice of such technology, process or
method, would infringe such Valid Claim (or, in the case of a Valid Claim that has not yet issued, would infringe such Valid Claim if it were to issue). 
 1.20 “Develop” or “Development” means all activities relating to non-clinical, preclinical and clinical trials, toxicology testing, modification, optimization and animal
efficacy testing of pharmaceutical compounds, statistical analysis, publication and presentation of study results and reporting, preparation and submission to Regulatory Authorities of applications (including any CMC information) relating to
Compounds (including Licensed Compounds and EPIZYME Compounds, as applicable), Targets (including Selected Targets, Dropped Targets and Terminated Targets, as applicable) and related products (including Licensed Products, EPIZYME Products,
Terminated Products, Diagnostic Products and EPIZYME Diagnostic Products, as applicable) and obtaining and maintaining Regulatory Approval thereof. 

  
 - 4 -

 1.21 “Development Candidate” means, with respect to a particular Selected
Target, a Compound directed to such Selected Target that is designated by the JSC pursuant to Section 2.4.3 as meeting the applicable Development Candidate Selection Criteria. 

1.22 “Development Candidate Selection Criteria” means the criteria to be achieved by Compounds directed to a Selected
Target as set forth in the Lead-2-Candidate row of Exhibit B. 
 1.23 “Diagnostic IP” means Diagnostic
Know-How and Diagnostic Patents. 
 1.24 “Diagnostic Know-How” means Know-How that is necessary or useful to
research, Develop, manufacture or Commercialize any Diagnostic Product in the Field in the Territory. 
 1.25
“Diagnostic Patents” means Patents claiming Diagnostic Know-How. 
 1.26 “Diagnostic Product”
means any biomarker or diagnostic assay or test that is designed for use with, or that relates to, is associated with or is correlated with patient populations that do or do not respond to treatment with any Licensed Product. 

1.27 “Dollars” or “$” means the legal tender of the U.S. 

1.28 “Eligible Dropped Target” means a Dropped Target that was a Selected Target for at least [**] months prior to being
dropped pursuant to Section 2.2.5. 
 1.29 “EMA” means the European Medicines Agency, and any successor
entity thereto. 
 1.30 “EPIZYME Blocked Targets” means the Targets set forth in Exhibit A. 

1.31 “EPIZYME Compound” means any Compound that is directed to a Dropped Target and satisfies the criteria set forth in
clause (c) of the definition of “Licensed Compound.” 
 1.32 “EPIZYME Diagnostic IP” means
EPIZYME Diagnostic Know-How and EPIZYME Diagnostic Patents. 
 1.33 “EPIZYME Diagnostic Know-How” means:

 (a) Diagnostic Know-How that is Controlled by EPIZYME as of the Effective Date or during the Term and arising outside of the
Collaboration, to the extent that such Know-How is necessary for the research, Development, making, use, offer for sale, selling, importing or other Commercialization of Diagnostic Products related to Licensed Products; and 

(b) Diagnostic Know-How that is Controlled by EPIZYME as of the Effective Date or during the [**] year period following the Effective
Date and arising outside of the Collaboration, to the extent that such Know-How is useful (but not necessary) for the research, Development, making, use, offer for sale, selling, importing or other Commercialization of Diagnostic Products related to
Licensed Products. 

  
 - 5 -

 For purposes of clarity, EPIZYME Diagnostic Know-How excludes EPIZYME Know-How,
Collaboration Know-How and EPIZYME’s interest in any Joint Know-How. 
 1.34 “EPIZYME Diagnostic Patents”
means Patents Controlled by EPIZYME as of the Effective Date or during the Term that claim any invention that is discovered, developed, invented, conceived or reduced to practice outside of the Collaboration and that Cover any Diagnostic Product
relating to a Licensed Product. 
 1.35 “EPIZYME Diagnostic Product” means any biomarker or diagnostic assay or
test designed for use with, or that relates to, is associated with or is correlated with patient populations that do or do not respond to treatment with any EPIZYME Product. 
 1.36 “EPIZYME IP” means EPIZYME Know-How and EPIZYME Patents. 

1.37 “EPIZYME Know-How” means: 
 (a) Know-How that is Controlled by EPIZYME as of the Effective Date or during the Term and arising outside of the Collaboration, to the extent that such Know-How is necessary for the research,
Development, making, use, offer for sale, selling, importing or other Commercialization of any Licensed Compounds or Licensed Products; and 
 (b) Know-How that is Controlled by EPIZYME as of the Effective Date or during the [**] year period following the Effective Date and arising outside of the Collaboration, to the extent that such Know-How
is useful (but not necessary) for the research, Development or Commercialization of Licensed Compounds or Licensed Products. 

For purposes of clarity, EPIZYME Know-How excludes EPIZYME Diagnostic Know-How, Collaboration Know-How and EPIZYME’s interest in any
Joint Know-How. 
 1.38 “EPIZYME Patents” means: 

(a) Patents that are Controlled by EPIZYME as of the Effective Date or during the Term that claim inventions discovered, developed,
invented, conceived or reduced to practice outside of the Collaboration, that (i) Cover the composition of matter or method of use of any Licensed Compound or Licensed Product or (ii) are otherwise necessary to research, Develop, make,
use, offer for sale, sell, import and otherwise Commercialize (but in the case of (ii), excluding such Patents that Cover technologies that are not applied to the applicable Licensed Product prior to the [**] anniversary of the Effective Date and
are not included under clause (b) below) any Licensed Compound or Licensed Product; and 
 (b) Patents other than those
included in the foregoing clause (a) that are Controlled by EPIZYME during the [**] year period following the Effective Date that claim inventions discovered, developed, invented, conceived or reduced to practice outside of the Collaboration
that are useful (but not necessary) to research, Develop, make, use, offer for sale, sell, import and otherwise Commercialize any Licensed Compound or Licensed Product, including Patents that claim formulation, delivery or manufacturing process
improvements. 

  
 - 6 -

 For purposes of clarity, EPIZYME Patents exclude EPIZYME Diagnostic Patents, Collaboration
Patents and EPIZYME’s interest in any Joint Patents. 
 1.39 “EPIZYME Product” means any pharmaceutical
product comprising an EPIZYME Compound, whether or not as the sole active ingredient and in any dosage form or formulation, excluding EPIZYME Diagnostic Products. 
 1.40 “EU” means all countries that are officially recognized as member states of the European Union at any particular time during the Term. 

1.41 “European Commission” means the executive body of the EU that has legal authority to grant marketing authorization
approvals for pharmaceutical products in the EU after scientific evaluation and recommendation from the EMA or other applicable Regulatory Authorities. 
 1.42 “Executive Officers” means EPIZYME’s Chief Executive Officer and GSK’s Senior Vice President of research and Development (or their respective designees). 

1.43 “FDA” means the U.S. Food and Drug Administration, and any successor entity thereto. 

1.44 “Field” means any use or purpose, including the treatment, palliation, diagnosis or prevention of any human or
animal disease, disorder or condition. 
 1.45 “First Commercial Sale” means: (a) with respect to each
Licensed Product, the first sale for which revenue has been recognized by GSK or its Affiliates or Sublicensees for use or consumption by the general public of such Licensed Product in any country in the Territory for which all Regulatory Approvals
and pricing or reimbursement approvals that are legally required in order to sell such Licensed Product in such country have been granted; and (b) with respect to each Royalty-Bearing EPIZYME Product, the first sale for which revenue has been
recognized by EPIZYME or its Affiliates or Sublicensees for use or consumption by the general public of such Royalty-Bearing EPIZYME Product in any country in the Territory for which all Regulatory Approvals and pricing or reimbursement approvals
that are legally required in order to sell such Royalty-Bearing EPIZYME Product in such country have been granted; in each case provided however that the following shall not constitute a First Commercial Sale: 

(i) any sale to an Affiliate or Sublicensee unless the Affiliate or Sublicense is the last entity in the distribution chain of the
Licensed Product or Royalty-Bearing EPIZYME Product, as applicable; 
 (ii) any use of such Licensed Product or Royalty-Bearing
EPIZYME Product, as applicable, in Clinical Trials, non-clinical Development activities or other Development activities, or disposal or transfer of Licensed Products or Royalty-Bearing EPIZYME Products, as applicable, for a bona fide charitable
purpose; and 
 (iii) compassionate use. 

  
 - 7 -

 1.46 “FTE” means a full-time individual’s work time dedicated by
EPIZYME to the performance of research activities under the applicable Research Plan, or in the case of less than a full-time dedicated individual, a full-time equivalent person year, for a twelve (12)-month period, based upon a total of [**] hours
per year of research work. For clarity, the Parties intend the FTE to be a unit of measurement used to calculate the amount of time dedicated to the performance of this Agreement by EPIZYME. One FTE may constitute work performed by an individual
whose time is dedicated solely to this Agreement or may comprise the efforts of several individuals, each of whom dedicates only part of his or her time to work under this Agreement. 

1.47 “FTE Cost” means, for any period, the product of (a) the actual total FTEs (or applicable portion thereof)
during such period, and (b) the FTE Rate. 
 1.48 “FTE Rate” means $[**] per FTE for
the period commencing on the Effective Date and ending December 31, 2011. On January 1, 2012 and on
January 1st of each subsequent Calendar Year, the
foregoing rate shall be increased for the Calendar Year then commencing by the percentage increase, if any, in the CPI as of December 31 of the then most recently completed Calendar Year over the level of the CPI as of December 31 of the
prior Calendar Year. As used in this Section 1.48, “CPI” means the Consumer Price Index – Urban Wage Earners and Clerical Workers, US City Average, All Items, 1982-84 = 100, published by the United States Department of
Labor, Bureau of Labor Statistics (or its successor equivalent index). 
 1.49 “GLP Toxicology Study” means a
toxicology study that is conducted in compliance with the then-current good laboratory practice standards promulgated or endorsed by the FDA, as defined in U.S. 21 C.F.R. Part 58 (or such other comparable regulatory standards in jurisdictions
outside the U.S. to the extent applicable to the relevant toxicology study, as they may be updated from time to time) (“GLP”) and is required to meet the requirements for filing an IND. 

1.50 “GSK IP” means GSK Know-How and GSK Patents. 

1.51 “GSK Know-How” means Know-How, excluding Collaboration Know-How, that is Controlled by GSK at any time during the
period commencing on the Effective Date and expiring upon the end of the Research Term, used in the conduct of the Collaboration and is either (a) necessary for the research, Development, making, use, offer for sale, selling, importing or other
Commercialization of, or (b) during the Collaboration, was incorporated into or used to manufacture, any EPIZYME Compounds or EPIZYME Products. For purposes of clarity, GSK Know-How includes Diagnostic Know-How Controlled by GSK, but excludes
GSK’s interest in any Joint Know-How. 
 1.52 “GSK Patent(s)” means Patents, excluding Collaboration
Patents, Controlled by GSK at any time during the period commencing on the Effective Date and expiring upon the end of the Research Term and that Cover GSK Know-How. For purposes of clarity, GSK Patents include Diagnostic Patents Controlled by GSK,
but exclude GSK’s interest in any Joint Patents. 

  
 - 8 -

 1.53 “IND” means an investigational new drug application submitted to the
FDA pursuant to Part 312 of Title 21 of the U.S. Code of Federal Regulations, including any amendments thereto. References herein to IND shall include, to the extent applicable, any comparable filing(s) outside the U.S. for the investigation of any
product in any other country or group of countries (such as a Clinical Trial Application (“CTA”) in the EU). 

1.54 “Indication” means any human disease or condition, or sign or symptom of a human disease or condition. 

1.55 “Initiation” means, with respect to a Clinical Trial, the first dosing of the first subject enrolled in such
Clinical Trial with a Licensed Product. 
 1.56 “Joint IP” means Joint Know-How and Joint Patent Rights.

 1.57 “Joint Know-How” means Know-How that is discovered, developed, invented, conceived or reduced to
practice by one or more employees, agents or consultants of EPIZYME, on the one hand, and one or more employees, agents or consultants of GSK on the other hand, in the conduct of activities under the Collaboration during the Research Term or as a
result of meetings during the Advisory Period. 
 1.58 “Joint Patents” means Patents that claim Joint Know-How.

 1.59 “Know-How” means all tangible and intangible: 

(a) information, techniques, technology, practices, trade secrets, inventions (whether patentable or not), methods, knowledge, know-how,
skill, experience, data, results (including pharmacological, toxicological and clinical test data and results, research data, reports and batch records), analytical and quality control data, analytical methods (including applicable reference
standards), full batch documentation, packaging records, release, stability, storage and shelf-life data, and manufacturing process information, results or descriptions, software and algorithms; and 

(b) compositions of matter, cells, cell lines, assays, animal models and physical, biological or chemical material. 

As used in this Agreement, “clinical test data” shall be deemed to include all information related to clinical or non-clinical
testing, including patient report forms, investigators’ reports, biostatistical, pharmaco-economic and other related analyses, regulatory filings and communications, and the like. 

1.60 “Law” or “Laws” means all laws, statutes, rules, regulations, orders, judgments, or ordinances
having the effect of law of any federal, national, multinational, state, provincial, county, city or other political subdivision. 
 1.61 “Lead Candidate” means, with respect to a particular Selected Target, a Compound directed to such Selected Target that is selected by the JSC pursuant to Section 2.4.2 as
meeting the applicable Lead Candidate Criteria. 

  
 - 9 -

 1.62 “Lead Candidate Criteria” means the criteria to be achieved by
Compounds directed to a Selected Target as set forth in the Hit-2-Lead row of Exhibit B. 
 1.63 “Licensed
Compound(s)” means any Compound that is: 
 (a) synthesized or identified by either Party (or by any of its respective
Affiliates or any Third Party working with or on behalf of such Party or any of its respective Affiliates) in the conduct of the Collaboration; 
 (b) directed to a Selected Target; and 
 (c) determined to
have an in vitro IC50 enzymatic potency of at least
[**] and [**] selectivity relative to the next most active Target. 
 For purposes of clarity, without limiting the generality of
Section 7.1, in the event that any Compound that satisfies the criteria set forth in the foregoing clauses (a), (b) and (c) is optimized by or on behalf of GSK after the Research Term, such optimized Compound shall also be deemed a
“Licensed Compound” for all purposes under this Agreement. In addition, any Compound that is identified from a GSK compound library pursuant to Section 2.3.4(a)(iii) that the Parties mutually agree to not progress under the
Collaboration shall not be deemed a Licensed Compound hereunder. 
 1.64 “Licensed Product(s)” means any
pharmaceutical product comprising a Licensed Compound, whether or not as the sole active ingredient and in any dosage form or formulation, excluding Diagnostic Products. 
 1.65 “MAA” means a regulatory application filed with the EMA or MHLW seeking Regulatory Approval of a Licensed Product, and all amendments and supplements thereto filed with the EMA or
MHLW. 
 1.66 “Major EU Country” means any of the following countries: France, Germany, Italy, Spain or the
United Kingdom. “Major EU Countries” means all of the foregoing countries. 
 1.67 “Major Market
Country(ies)” means (a) the United States, (b) Japan or (c) the Major EU Countries. 
 1.68
“MHLW” means the Ministry of Health, Labour and Welfare of Japan, or the Pharmaceuticals and Medical Devices Agency, or any successor to either of them, as the case may be. 

1.69 “NDA” means a New Drug Application (as more fully described in 21 C.F.R. 314.50 et seq. or its successor
regulation) and all amendments and supplements thereto filed with the FDA, or any equivalent filing, including an MAA, in a country or regulatory jurisdiction other than the United States. 

1.70 “Net Sales” means with respect to any Licensed Product, the gross amounts invoiced by GSK, its Affiliates and
Sublicensees (each, a “Selling Party”) to Third Party 

  
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customers for sales of such Licensed Product, less the following deductions actually incurred, allowed, paid, accrued or specifically allocated in its financial statements in accordance with (as
applicable to the Selling Party) GAAP or IFRS, for: 
 (a) customary and reasonable trade, quantity, and cash discounts and
wholesaler allowances; 
 (b) customary and reasonable credits, rebates and chargebacks (including those to managed-care
entities and government agencies), and allowances or credits to customers on account of rejection or returns (including, but not limited to, wholesaler and retailer returns) or on account of retroactive price reductions affecting such Licensed
Product; 
 (c) freight, postage and duties, and transportation charges relating to such Licensed Product, including handling
and insurance thereto; 
 (d) sales (such as VAT or its equivalent) and excise taxes, other consumption taxes, customs duties
and compulsory payments to governmental authorities and any other governmental charges imposed upon the importation, use or sale of such Licensed Product to Third Parties (excluding any taxes paid on the income from such sales) to the extent the
Selling Party is not otherwise entitled to a credit or a refund for such taxes, duties or payments made; and 
 (e) amounts
previously included in Net Sales that are written-off by the Selling Party as uncollectible in accordance with the standard practices of such Selling Party for writing off uncollectible amounts, consistently applied; provided however that if
any such written-off amounts are subsequently collected, such collected amounts shall be included in Net Sales in the period in which they are subsequently collected. 
 If non-monetary consideration is received for any Licensed Product, Net Sales will be calculated based on the average price charged for such Licensed Product during the preceding royalty period, or in the
absence of such sales, the fair market value of the Licensed Product, as determined by the Parties in good faith. If the Parties are unable to reach such an agreement, the Parties will refer such matter to a jointly selected Third Party with
expertise in the pricing of pharmaceutical products that is not an employee, consultant, legal advisor, officer, director or stockholder of, and does not have any conflict of interest with respect to, either Party for resolution. If the Parties are
unable to agree on such a Third Party expert within [**] days after a Party has notified the other Party that it desires to refer such matter to such a Third Party for resolution, either Party may request that the New York, New York office of the
American Arbitration Association (“AAA”) appoint such an expert to resolve such matter. The resolution determined by any such expert that is either jointly selected or appointed by the AAA shall be final and binding on the Parties.
Notwithstanding the foregoing, Net Sales shall not be imputed to transfers of Licensed Product or Royalty-Bearing EPIZYME Product, as applicable, for use in clinical trials, non-clinical Development activities or other Development activities, for
bona fide charitable purposes or for compassionate use if no monetary consideration is received for such transfers. 

  
 - 11 -

 Net Sales shall be determined on, and only on, the first sale by a Party or any of its
Affiliate or Sublicensees to a non-Sublicensee Third Party. 
 Notwithstanding the deductions set forth in clause (a) or
(b) above, if pursuant to a formulary agreement in the United States, there are any discounts (including cash discounts and quantity discounts), credits, rebates, chargebacks, reductions or payments for any Licensed Product based on sales to
the Third Party customer of a bundled set of products in which such Licensed Product is included, then the applicable discount, credit, rebate, chargeback, reduction or payment for such Licensed Product in such bundled arrangement shall be based on
the average discount, credit, rebate, chargeback, reduction or payment for all products in such bundle for the purposes of determining Net Sales of such Licensed Product in the United States. 

If a Licensed Product is sold as part of a Combination Product (as defined below), Net Sales will be the product of (i) Net Sales of
the Combination Product calculated as above (i.e., calculated as for a non-Combination Product) and (ii) the fraction (A/(A+B)), where: 
 “A” is the average wholesale acquisition cost of the Licensed Product comprising a Licensed Compound as the sole therapeutically active ingredient during the four (4) most recently
completed Calendar Quarters during which such non-Combination Products were sold in such country; and 
 “B” is the
average wholesale acquisition cost in such country of the other therapeutically active ingredients contained in the Combination Product when sold separately during the four (4) most recently completed Calendar Quarters during which such
products were sold in such country. 
 If “A” or “B” cannot be determined by reference to non-Combination
Product sales as described above, then Net Sales for purposes of determining royalty payments will be calculated as above, but the average wholesale acquisition cost in the above equation shall be determined by mutual agreement reached in good faith
by the Parties prior to the end of the accounting period in question based on an equitable method of determining same that takes into account, in the applicable country, variations in dosage units and the relative fair market value of each
therapeutically active ingredient in the Combination Product. If the Parties are unable to reach such an agreement prior to the end of the applicable accounting period, then the Parties will refer such matter to a jointly selected Third Party with
expertise in the pricing of pharmaceutical products that is not an employee, consultant, legal advisor, officer, director or stockholder of, and does not have any conflict of interest with respect to, either Party for resolution. If the Parties are
unable to agree on such a Third Party expert within [**] days after a Party has notified the other Party that it desires to refer such matter to such a Third Party for resolution, either Party may request that the New York, New York office of the
AAA appoint such an expert to resolve such matter. The resolution determined by any such expert that is either jointly selected or appointed by the AAA shall be final and binding on the Parties. 

As used in this Section 1.70, “Combination Product” means a Licensed Product that contains one or more additional
active ingredients (whether coformulated or copackaged) that are neither Licensed Compounds nor generic or other non-proprietary compositions-of-matter. Pharmaceutical dosage form vehicles, adjuvants and excipients shall be deemed not to be
“active ingredients”. 

  
 - 12 -

 To the extent the Net Sales definition is used herein with respect to Royalty-Bearing
EPIZYME Products, Net Sales shall have the meaning set forth above, with all references to “GSK” replaced by “EPIZYME”, all references to “Licensed Product” replaced with “Royalty-Bearing EPIZYME Product”, and
all references to “Diagnostic Product” replaced with “EPIZYME Diagnostic Product”. 
 1.71
“Out-of-Pocket Costs” means, with respect to activities performed under the applicable Research Plan hereunder, direct expenses of EPIZYME or its Affiliates that are specifically associated with the conduct of such activities,
including costs of consultants, agents and subcontractors, recorded in accordance with GAAP. 
 1.72 “Patent”
means (a) all patents and patent applications in any country or supranational jurisdiction in the Territory, (b) any substitutions, divisionals, continuations, continuations-in-part, provisional applications, reissues, renewals,
registrations, confirmations, re-examinations, extensions, supplementary protection certificates and the like of any such patents or patent applications, and (c) foreign counterparts of any of the foregoing. 

1.73 “Patent-Based Exclusivity” means: 
 (a) with respect to a Licensed Product in a country in the Territory, that at least one Valid Claim of the EPIZYME Patents, Collaboration Patents Controlled by EPIZYME or the Joint Patents Covers such
Licensed Product in such country; or 
 (b) with respect to a Royalty-Bearing EPIZYME Product in a country in the Territory,
that at least one Valid Claim of the GSK Patents, Collaboration Patents Controlled by GSK or the Joint Patents, in each case that is exclusively licensed to EPIZYME pursuant to Section 5.2.2, Covers such Royalty-Bearing EPIZYME Product in such
country. 
 1.74 “Person” means any individual, partnership, joint venture, limited liability company,
corporation, firm, trust, association, unincorporated organization, governmental authority or agency, or any other entity not specifically listed herein. 
 1.75 “Phase 1 Clinical Trial” means a human clinical trial of a product in any country, the principal purpose of which is a preliminary determination of safety in healthy individuals or
patients, that would satisfy the requirements of 21 C.F.R. 312.21(a), or a similar clinical study prescribed by the relevant Regulatory Authorities in a country other than the United States. 

1.76 “Phase 2 Clinical Trial” means a human clinical trial of a product in any country that would satisfy the
requirements of 21 C.F.R. 312.21(b) and is intended to explore a variety of doses, dose response, and duration of effect, and to generate initial evidence of clinical safety and activity in a target patient population, or a similar clinical study
prescribed by the relevant Regulatory Authorities in a country other than the United States. 

  
 - 13 -

 1.77 “Phase 3 Clinical Trial” means a human clinical trial of a product in
any country that would satisfy the requirements of 21 C.F.R. 312.21(c) and is intended to (a) establish that the product is safe and efficacious for its intended use, (b) define warnings, precautions and adverse reactions that are
associated with the product in the dosage range to be prescribed, and (c) support Regulatory Approval for such product. 

1.78 “Prosecution and Maintenance” or “Prosecute and Maintain” means, with regard to a Patent, the
preparation, filing, prosecution and maintenance of such Patent, as well as re-examinations, reissues, appeals, and requests for patent term adjustments and patent term extensions with respect to such Patent, together with the initiation or defense
of interferences, the initiation or defense of oppositions and other similar proceedings with respect to the particular Patent, and any appeals therefrom. For clarification, “Prosecution and Maintenance” or “Prosecute and
Maintain” shall not include any other enforcement actions taken with respect to a Patent. 
 1.79 “Regulatory
Approval” means the approval, license or authorization of the applicable Regulatory Authority necessary for the marketing and sale of a product for a particular Indication in a country in the Territory, excluding separate pricing or
reimbursement approvals that may be required, and including the approval by the applicable Regulatory Authority of any expansion or modification of the label for such Indication. 

1.80 “Regulatory Authority” means the FDA in the U.S. or any health regulatory authority in another country in the
Territory that is a counterpart to the FDA and holds responsibility for granting Regulatory Approval for a product in such country, including the EMA and the MHLW, and any successor(s) thereto. 

1.81 “Regulatory Materials” means the regulatory registrations, applications, authorizations and approvals (including
approvals of NDAs, supplements and amendments, pre- and post-approvals, pricing and Third Party reimbursement approvals, and labeling approvals), Regulatory Approvals or other submissions made to or with any Regulatory Authority necessary for the
Development (including the conduct of clinical studies), manufacture, distribution, marketing, promotion, offer for sale, use, import, reimbursement, export or sale of a Licensed Compound, Licensed Product or Diagnostic Product in a regulatory
jurisdiction, together with all related correspondence to or from any Regulatory Authority and all documents referenced in the complete regulatory chronology for each NDA, including all Drug Master File(s) (if any), IND, CTA, NDA, MAA and
supplemental new drug applications (sNDAs) or foreign equivalents. 
 1.82 “Research Plan” means, with respect
to each Selected Target, a research plan governing the activities to be conducted by the Parties during the Research Term directed to such Selected Target, with the goal of identifying Compounds directed to such Selected Target that meet the
applicable Development Candidate Selection Criteria, as well as Licensed Compounds that may be suitable as backups or replacements for the Development Candidate against the applicable Selected Target. 

1.83 “Selection Term” means the period commencing on the Effective Date and ending [**] following the Effective Date.

  
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 1.84 “Sublicensee” means (a) with respect to GSK, a Third Party to
whom GSK has granted a license under Know-How or Patents Controlled by GSK, or a sublicense under Know-How or Patents licensed to GSK pursuant to this Agreement, to research, Develop, manufacture or Commercialize Licensed Compounds, Licensed
Products or Diagnostic Products in the Field, and (b) with respect to EPIZYME, a Third Party to whom EPIZYME has granted a license under Know-How or Patents Controlled by EPIZYME, or a sublicense under Know-How or Patents licensed to EPIZYME
pursuant to this Agreement, to research Licensed Compounds or to research, Develop, manufacture or Commercialize EPIZYME Compounds, EPIZYME Products or EPIZYME Diagnostic Products in the Field; but in each case excluding any Third Party acting
solely as a distributor. 
 1.85 “Target” means a target (i.e., a nucleic acid sequence and/or the protein that
it encodes), for which there is reasonable evidence (based upon bioinformatics analysis or other supportive data) to suggest that such target is of a class that is capable of being modulated by a Compound. 

1.86 “Target Validation” means achievement of the first three criteria set forth in the “Desired Criteria to Reach
Milestone” column of the “Target Validation” row of Exhibit B. 
 1.87 “Territory” means
the entire world. 
 1.88 “Third Party” means any Person other than EPIZYME or GSK that is not an Affiliate of
EPIZYME or of GSK. 
 1.89 “Tractable Hit” means, when directed to a particular Target, a Compound that meets
the Tractable Hit Criteria. 
 1.90 “Tractable Hit Criteria” means the criteria to be achieved by Compounds
directed to a Selected Target as set forth in the Target-2-Hit row of Exhibit B. 
 1.91 “United States”
or “U.S.” means the United States of America and all of its territories and possessions. 
 1.92 “Valid
Claim” means: 
 (a) a claim of an issued patent in the U.S. or in a jurisdiction outside the U.S., that has not
expired, lapsed, been cancelled or abandoned, or been dedicated to the public, disclaimed, or held unenforceable, invalid, or cancelled by a court or administrative agency of competent jurisdiction in an order or decision from which no appeal has
been or can be taken, including through opposition, reexamination, reissue or disclaimer; or 
 (b) a claim of a pending patent
application that has not been finally abandoned or finally rejected and which has been pending for no more than [**] years from the date of filing of the earliest priority patent application to which such pending patent application is entitled to
claim benefit. 

  
 - 15 -

 For clarity, a claim of an issued patent that ceased to be a Valid Claim before it issued
because it had been pending too long, but subsequently issued and is otherwise described by clause (a) of the foregoing sentence shall again be considered to be a Valid Claim once it issues. The same principle shall apply in similar
circumstances such as if, for example (but without limitation), a final rejection of a claim is overcome. 
 1.93 Additional
Definitions. Each of the following definition is set forth in the section of this Agreement indicated below: 
  

			
	 Definition:
	 	 Section:

		
	AAA	 	1.70
	Advisory Period	 	3.1.2
	Agreement	 	Preamble
	Alliance Manager	 	4.5
	Arbitration Request	 	13.2
	Bankruptcy Code	 	5.4
	Breaching Party	 	12.3.1(a)
	Chairperson	 	4.1.1
	Claims	 	11.1
	Collaboration	 	2.1
	Competitive Infringement	 	8.5.1
	Confidential Information	 	9.1
	Disclosing Party	 	9.1
	Dropped Target(s)	 	2.2.5
	Effective Date	 	Preamble
	EPIZYME	 	Preamble
	EPIZYME Patent Challenge	 	12.4.2(b)
	Existing Confidentiality Agreement	 	9.4
	First Meeting	 	2.2.3
	GAAP	 	13.15
	GLP	 	1.49
	GSK	 	Preamble
	GSK Patent Challenge	 	12.4.1(b)
	HMT	 	Recitals
	IFRS	 	13.15
	Indemnified Party	 	11.3.1
	Indemnifying Party	 	11.3.1
	Initial ROFO Target Selection Period	 	2.2.4
	Joint Project Team (JPT)	 	4.3
	JSC	 	4.1
	Key Employee	 	13.13
	Know-How Royalty	 	6.8.2(b)
	Losses	 	11.1
	Material Receiving Party	 	2.7.5(a)
	Materials	 	2.7.5(a)

  
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	 Definition:
	 	 Section:

	Non-Breaching Party	 	12.3.1(a)
	Oncology-Inflammation Available Target	 	2.2.3
	Party or Parties	 	Preamble
	Passed ROFO Target(s)	 	2.2.4
	Passed ROFO Target Selection Blackout Period	 	2.2.4
	Patent Liaison	 	4.4
	Patent Strategy	 	4.4
	Payee	 	6.11
	Payor	 	6.11
	PMA	 	6.6
	publishing Party	 	9.6.2
	Purpose	 	2.7.5(a)
	Qualified Financing	 	6.3
	Receiving Party	 	9.1
	Replacement Target	 	2.2.6(a)
	Research Payments	 	6.2
	Research Term	 	2.3.1
	Reviewing Party	 	9.6.2
	ROFO Package	 	2.2.4
	Royalty-Bearing EPIZYME Product	 	6.9.1
	Royalty Term	 	6.8.2(a)
	Selected Target(s)	 	2.2.2
	Sensitive Information	 	7.1.2(b)
	Subcommittee	 	4.2
	Term	 	12.1.1
	Terminated Dropped Target	 	12.5.3
	Terminated EPIZYME Products	 	12.5.3
	Terminated Products	 	12.5.1
	Terminated Target	 	12.5.1
	Transfer Record	 	2.7.5(a)
	Transferring Party	 	2.7.5(a)
	US/UK Treaty	 	6.13.1

 ARTICLE 2 
 TARGET SELECTION; COLLABORATION ACTIVITIES 
 2.1 Collaboration
Overview. Pursuant to this Agreement (including the Research Plans) and as further provided in this Article 2, the Parties shall (a) perform platform discovery activities with the goal of identifying Available Targets, (b) select
Selected Targets, where up to three (3) Selected Targets at any given point in time may be the subject of activities conducted by EPIZYME under the terms of the Agreement (including the Research Plans), and (c) conduct activities pursuant
to a Research Plan for each Selected Target with the goal of identifying Compounds directed to such Selected Target that meet the applicable Development Candidate Selection Criteria (the “Collaboration”). 

  
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 2.2 Targets. 

2.2.1 Overview. During the Selection Term, EPIZYME shall use its Commercially Reasonable Efforts to conduct appropriate platform
discovery activities in order to characterize Targets prioritized pursuant to Section 2.2.3, identify potential Available Targets for selection by GSK for inclusion in the Collaboration and shall provide regular updates to GSK, at JPT meetings
in accordance with Section 2.5, with respect to the identification of each potential Available Target together with all material data and information in EPIZYME’s possession and Control relating to such Available Target. GSK may, but shall
not be required to, identify potential Available Targets for selection by GSK for inclusion in the Collaboration. Once an Available Target is selected as a Selected Target pursuant to Section 2.2.2, a Research Plan for such Selected Target
shall be promptly agreed between the Parties in accordance with Section 2.3.2 to include the discovery and other research of Compounds and Licensed Compounds directed to such Selected Targets. 

2.2.2 Selected Targets. During the Selection Term, GSK shall have the right to select, from the Available Targets, up to three
(3) Targets at the same time at any given point in time (each, a “Selected Target”), each of which shall be the focus of activities under a Research Plan. For clarity, at no one point in time shall more than three
(3) Targets be designated as Selected Targets. While the Parties shall discuss the characteristics and relative scientific merits of each Available Target that is of potential interest, GSK shall have the final decision of whether and which
Available Targets to select to be Selected Targets under this Agreement. 
 2.2.3 Discussion of Available Targets; ROFO
Packages. At the earlier of either the first JSC meeting or the first JPT meeting following the Effective Date (the “First Meeting”), EPIZYME shall provide to GSK all material data and information within EPIZYME’s
possession and Control pertaining to all Available Targets identified by EPIZYME as of the Effective Date. Thereafter during the Selection Term, EPIZYME shall notify GSK, on a regular basis at JPT meetings, of additional Available Targets identified
by EPIZYME in the course of its ongoing platform discovery activities as well as notify GSK with respect to material developments in new data or information in EPIZYME’s possession and Control relating to previously identified Available Targets
that remain Available Targets. Further, GSK may request that EPIZYME prioritize its platform discovery activities with respect to particular Targets and EPIZYME shall consider such requests in good faith, taking into consideration GSK’s
strategic interests, as well as the Parties’ discussion of the characteristics and scientific merits of such Available Targets. For the avoidance of doubt, the foregoing provisions of data or other notifications regarding Available Targets
shall include EPIZYME’s reasonable determination as to whether the primary therapeutic hypothesis for a particular Available Target relates to oncology Indication(s) or inflammation Indication(s) based on then-existing literature or data (an
“Oncology-Inflammation Available Target”); provided, that if EPIZYME determines that an Available Target is not an Oncology-Inflammation Available Target, then GSK may require further discussion if GSK is aware of data or literature
that supports GSK’s belief that such Available Target is an Oncology-Inflammation Available Target. 
 2.2.4 ROFO
Package; Passed ROFO Targets. After the First Meeting, EPIZYME may provide written notice to GSK if EPIZYME has a bona fide interest in seeking a 

  
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Third Party collaborator or licensee with respect to an Available Target, together with all material data and information in EPIZYME’s possession and Control relating to such Available
Target (the “ROFO Package”); provided that EPIZYME shall use reasonable efforts to provide such ROFO Package within [**] Business Days prior to the next-scheduled meeting of the JSC; and provided, further that
if EPIZYME does not provide such ROFO Package within such timeframe, then EPIZYME may request a maximum of one (1) ad hoc meeting of the JSC per Calendar Quarter to review the applicable ROFO Packages, which ad hoc JSC meeting
shall occur within [**] Business Days following delivery of such ROFO Packages to GSK. With respect to Oncology-Inflammation Available Targets, the ROFO Package shall include data demonstrating satisfaction of the first three criteria set forth in
the “Desired Criteria to Reach Milestone” column of the “Target Validation” row of Exhibit B. GSK shall have [**] Business Days after the JSC meeting at which the applicable ROFO Package was discussed (the “Initial ROFO
Target Selection Period”) to select the applicable Available Target as a Selected Target in accordance with Section 2.2.2. If GSK does not select any such offered Available Target as a Selected Target during the applicable Initial ROFO
Target Selection Period (each such non-selected Available Target, a “Passed ROFO Target”), such Passed ROFO Target shall not be available for selection by GSK as a Selected Target during the [**] day period following the end of the
applicable Initial ROFO Target Selection Period (the “Passed ROFO Target Selection Blackout Period”). EPIZYME shall have the right to initiate an internal program or seek a Third Party collaborator or licensee for any Passed ROFO
Target; provided however that, following the applicable Passed ROFO Target Selection Blackout Period, such Passed ROFO Target shall again become an Available Target, eligible for potential selection as a Selected Target by GSK
during the remainder of the Selection Term, unless and until: 
 (a) such Passed ROFO Target (or Compound(s) directed thereto)
has been licensed by EPIZYME to a Third Party collaborator or licensee; or 
 (b) EPIZYME has notified GSK that a GLP
Toxicology Study has been commenced by or on behalf of EPIZYME with respect to a Compound directed to such Passed ROFO Target and GSK does not select such Passed ROFO Target as a Selected Target on or before the date that is [**] days following such
notification. 
 If GSK selects any Passed ROFO Target as a Selected Target pursuant to this Section 2.2.4, GSK shall
reimburse EPIZYME for any costs or expenses incurred by EPIZYME in connection with the conduct of any GLP Toxicology Study with respect to such Passed ROFO Target as well as any costs or expenses incurred in manufacturing quantities of Licensed
Compounds required for such GLP Toxicology Study, through the date of GSK’s selection of such Passed ROFO Target as a Selected Target hereunder; provided that, if EPIZYME has incurred costs or expenses in manufacturing quantities
of Licensed Compounds beyond the quantities required for such GLP Toxicology Study, GSK shall only be responsible for such costs or expenses relating to the excess quantities if GSK requests that EPIZYME provide such excess quantities to GSK.

 For purposes of clarity, upon the occurrence of the condition(s) specified in the foregoing clause (b) without timely
selection by GSK or the occurrence of the condition(s) specified in the foregoing clause (a), such Passed ROFO Target shall no longer be an Available Target. 

  
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 2.2.5 Dropped Targets. During the Research Term, GSK shall have the right to drop any
Selected Target upon written notice to EPIZYME (each such dropped Selected Target, a “Dropped Target”), and effective upon EPIZYME’s receipt of such notice such Dropped Target shall cease to be a Selected Target and EPIZYME
shall cease and no longer be obligated to conduct activities directed to such Dropped Target under the applicable Research Plan. Following the date on which a Selected Target becomes a Dropped Target, such Dropped Target shall not be available for
re-selection by GSK as a Selected Target. 
 2.2.6 Replacement Targets. 

(a) Subject always to the three (3)-Selected Target limitation set forth in Section 2.2.2, any Target selected by GSK to replace a
Selected Target pursuant to Section 2.2.2 after GSK has selected all of the first three (3) Selected Targets hereunder (for example, a Target selected to replace the third Selected Target after dropping such Selected Target) shall be
deemed a “Replacement Target.” 
 (b) If GSK selects a Replacement Target pursuant to Section 2.2.2, then
subject to a new mutually agreed Research Plan in accordance with Section 2.3.2, the Parties shall undertake activities under such Research Plan directed to such Replacement Target for the remainder of the Research Term, subject to
Section 2.3.3 and Section 6.2. 
 2.3 Research Term; Research Plan; Research Activities. 

2.3.1 Research Term. The term for conducting activities under the Research Plans under the Collaboration
shall commence upon the Effective Date and continue until the fourth (4th) anniversary of the Effective Date (the “Research Term”). 

2.3.2 Research Plan. The initial Research Plan, attached hereto as Exhibit B, sets forth a template for the activities
expected to be performed by the Parties with respect to Selected Targets. As soon as possible (but no later than [**] days) following GSK’s selection of each Selected Target pursuant to Section 2.2.2, a specific Research Plan shall be
established by the JPT, with respect to such Selected Target for approval by the JSC, which Research Plan shall be substantially similar to the Research Plan attached hereto as Exhibit B; provided however that any
material deviations from the Research Plan set forth in Exhibit B shall be subject to mutual agreement of the Parties. 
 2.3.3 FTE Budgets for the 4th Year of the Research Term. On a date that is not later than [**] months from the Effective Date, the Parties shall agree on a budget of FTE Costs and Out-of-Pocket
Costs expected to be incurred by EPIZYME in the performance of each Research Plan for the fourth (4th) year of the Research Term based on the then-expected activities, if any, to occur during such year. The Parties shall review and update by
mutual agreement, as necessary, such budget in advance of each Calendar Quarter during the fourth (4th) year of the Research Term. 
 2.3.4 Responsibilities. 

(a) EPIZYME Responsibilities. During the Research Term: 

(i) EPIZYME shall use Commercially Reasonable Efforts to conduct platform discovery activities necessary to characterize Targets
prioritized pursuant to 2.2.3. In addition, EPIZYME shall be primarily responsible for the conduct of activities under the Research Plans during the Collaboration. EPIZYME shall use Commercially Reasonable Efforts to perform the activities assigned
to EPIZYME under the Research Plan, including, if applicable and subject to clause (a)(iii) below, screening using EPIZYME’s proprietary assays and generation of Compounds. 

  
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 (ii) EPIZYME shall use Commercially Reasonable Efforts to provide GSK, at no additional
cost to GSK and at GSK’s request, with reasonable quantities of Compounds Controlled by EPIZYME directed to the applicable Selected Target for the conduct of discovery and other research activities. 

(iii) As between the Parties, EPIZYME shall be responsible for the identification and generation of Compounds for which initial
activities shall be conducted by the Parties under the Research Plan. Unless otherwise mutually agreed by the Parties that GSK’s compound library will be screened under the Collaboration, the compound libraries and Compounds screened under the
Collaboration shall be those Controlled by EPIZYME. Compounds identified during the screening of GSK’s compound library may be progressed under the Collaboration only upon mutual agreement of the Parties; provided, that if the Parties do not
mutually agree to progress such Compounds, then such Compounds shall not be deemed Licensed Compounds. 
 (b) GSK
Responsibilities. Notwithstanding that EPIZYME is primarily responsible for the conduct of the activities set forth in the Research Plans, GSK shall be responsible for, and shall use Commercially Reasonable Efforts to perform, the activities
assigned to GSK under the Research Plan, including, if applicable, the provision of assays, crystallography, and, subject to clause (a)(iii) above, libraries Controlled by GSK for screening. In addition, GSK has the right but not the obligation to
provide the foregoing resources or conduct the foregoing activities at GSK’s discretion and cost, whether or not the same are set forth in the Research Plan. 
 (c) Operational Control. Notwithstanding anything in this Agreement to the contrary, subject to mutual agreement of the Parties on the Research Plan (including any amendments or updates thereto),
the Party specifically designated as being responsible for a particular activity under such Research Plan shall have operational control over such activity. 
 2.4 Tractable Hits; Lead Candidates; Development Candidates. Subject to the foregoing obligations to use Commercially Reasonable Efforts, neither Party provides any representation, warranty or
guarantee that the Collaboration will be successful, that any Tractable Hit will be identified, that any Lead Candidate Criteria or Development Candidate Selection Criteria will be achieved, or that any other particular results will be achieved with
respect to the Collaboration or any Selected Target, Compound, Licensed Compound, Licensed Product or Diagnostic Product hereunder. 

  
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 2.4.1 Selection of Tractable Hit. On a Selected Target-by-Selected Target basis, the
JPT shall make a recommendation as to whether or not a Compound satisfies the applicable Tractable Hit Criteria, for review and approval by the JSC. Upon the JSC’s determination that any Compound satisfies the applicable Tractable Hit Criteria,
such Compound shall be deemed a Tractable Hit for all purposes hereunder. 
 2.4.2 Selection of Lead Candidate. On a
Selected Target-by-Selected Target basis, the JPT shall make a recommendation as to whether or not a Compound satisfies the applicable Lead Candidate Criteria, for review and approval by the JSC. Upon the JSC’s determination that any Compound
satisfies the applicable Lead Candidate Criteria, such Compound shall be deemed the Lead Candidate for all purposes hereunder. 

2.4.3 Selection of Development Candidate. On a Selected Target-by-Selected Target basis, the JPT shall make a recommendation as to
whether or not a Compound satisfies the applicable Development Candidate Selection Criteria, for review and approval by the JSC. Upon the JSC’s determination that any Compound satisfies the applicable Development Candidate Selection Criteria,
such Compound shall be deemed the Development Candidate for all purposes hereunder. 
 2.4.4 No Other Research or Development
Activities. For purposes of clarity, notwithstanding anything in this Agreement to the contrary, EPIZYME shall not be obligated to conduct activities with respect to Selected Targets in addition to those contemplated under the applicable
Research Plan, regardless of whether a Compound identified or synthesized under the Collaboration fails to meet the applicable Lead Candidate Criteria or Development Candidate Selection Criteria. The foregoing does not limit EPIZYME’s
obligation to characterize the Targets as provided in Section 2.3.4(a)(i). 
 2.5 Reports; Results. Until the end of
the Research Term, each Party shall provide written progress reports on the status of its activities under Research Plans during the Collaboration, on a Selected Target-by-Selected Target basis, including detailed summaries of data associated with
such activities and, in the case of EPIZYME, reasonably detailed summaries of data generated in the course of its ongoing platform discovery activities to the extent not previously provided to GSK and relevant to the identification or attractiveness
for selection of potential Available Targets under Section 2.2, at least [**] Business Days in advance of each JPT meeting. 
 2.6 Subcontracting. 
 2.6.1 Subject to the terms of this Agreement, each
Party shall have the right to engage Affiliates or Third Party subcontractors to perform certain of its obligations under this Agreement. Any Affiliate or subcontractor to be engaged by a Party to perform a Party’s obligations set forth in this
Agreement shall meet the qualifications typically required by such Party for the performance of work similar in scope and complexity to the subcontracted activity; provided however that any Party engaging an Affiliate or
subcontractor hereunder shall remain principally responsible and obligated for such activities. In addition, any Party engaging a subcontractor shall in all cases retain or obtain Control of any and all Know-How or Patents

  
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related to the Collaboration, which may be created by or used with the relevant Party’s permission by such subcontractor in connection with such subcontracted activity (other than Know-How
and Patents that are not specific to the Collaboration and that are related to the subcontractor’s broader technology platform or business), and to require that such subcontractor conduct its activities in compliance with the policies set forth
in the attached Exhibit C (to the extent such policies are applicable to the activities being conducted by that subcontractor). 
 2.6.2 GSK shall have the right to audit and inspect EPIZYME’s activities under the Research Plans, which shall include the right to access EPIZYME’s records (including records from its major
subcontractors regarding work conducted under the Research Plans) and facilities as reasonably requested by GSK to confirm EPIZYME’s compliance with the requirements of and performance under this Agreement. Such audit and inspection shall not
be performed more than [**] in any Calendar Year and shall be reasonably coordinated in advance with EPIZYME. EPIZYME shall use Commercially Reasonable Efforts to obtain the right for GSK to audit the facilities of EPIZYME’s major
subcontractors. If EPIZYME cannot secure such audit rights for GSK, then to the extent that EPIZYME has the right itself to audit its subcontractors’ facilities, EPIZYME shall conduct such audit as reasonably requested by GSK and on the terms
agreed with such subcontractor and share the results with GSK. 
 2.7 Regulatory Matters; Compliance. 

2.7.1 Compliance. The Parties shall conduct all of their respective activities under this Agreement in good scientific manner, and
shall comply in all material respects with applicable Laws and use Commercially Reasonable Efforts to comply in all material respects with the policies set forth in the attached Exhibit C (to the extent such policies are applicable to the
activities being conducted by that Party) and, to the extent applicable, all other requirements of cGMP, GLP and current good clinical practice. 
 2.7.2 Data Integrity. Each of the Parties acknowledges the importance of ensuring that the activities conducted under this Agreement are undertaken in accordance with the following good data
management practices, and shall use Commercially Reasonable Efforts to ensure the following: 
 (a) data are being generated
using sound scientific techniques and processes; 
 (b) data are being accurately and reasonably contemporaneously recorded in
accordance with good scientific practices by personnel conducting research or development hereunder; 
 (c) data are being
analyzed appropriately without bias in accordance with good scientific practices; and 
 (d) data and results are being stored
securely and can be easily retrieved. 
 2.7.3 Regulatory Filings and Data. GSK shall be solely responsible for
preparing, filing and maintaining all regulatory filings (including pricing and reimbursement 

  
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approvals) and Regulatory Approvals necessary for the Development, manufacture or Commercialization of Licensed Compounds, Licensed Products and Diagnostic Products in the Field in the Territory.
GSK shall own all such regulatory filings and Regulatory Approvals. 
 2.7.4 Adverse Event Reporting; Global Safety
Database. GSK shall be solely responsible for reporting all adverse drug experiences associated with Licensed Compounds, Licensed Products and Diagnostic Products in the Field in the Territory, and for establishing, holding and maintaining the
global safety database for Licensed Compounds, Licensed Products and Diagnostic Products in the Field in the Territory. 
 2.7.5
Material Transfer. 
 (a) In addition to Compounds which may be provided by EPIZYME to GSK pursuant to
Section 2.3.4(a)(ii), to facilitate activities of the Parties in connection with this Agreement, either Party (referred to in this Section 2.7.5 as the “Transferring Party”) may, at its sole discretion, provide to the
other Party (referred to in this Section 2.7.5 as the “Material Receiving Party”) certain biological materials or compounds, including assays and research tools Controlled by the Transferring Party (such materials or compounds
provided hereunder are referred to, collectively, as “Materials”) for use by the Material Receiving Party in furtherance of its rights and the conduct of its obligations under this Agreement (the “Purpose”). All
transfers of such Materials by the Transferring Party to the Material Receiving Party shall be documented in writing (the “Transfer Record”) that sets forth the type and name of the Material transferred, the amount of the Material
transferred, the date of the transfer of such Material and the Purpose. 
 (b) Except as otherwise provided under this
Agreement, all such Materials delivered by the Transferring Party to the Material Receiving Party shall remain the sole property of the Transferring Party, shall only be used by the Material Receiving Party in furtherance of the Purpose, and shall
be returned to the Transferring Party upon the termination of this Agreement or upon the discontinuation of the use of such Materials (whichever occurs first). The Material Receiving Party shall not cause the Materials to be used by or delivered to
or for the benefit of any Third Party without the prior written consent of the Transferring Party. 
 (c) At the time the
Transferring Party provides Materials to the Material Receiving Party as provided herein and to the extent not separately licensed under this Agreement, the Transferring Party hereby grants to the other Party a non-exclusive license under the
Patents and Know-How Controlled by it to use such Materials solely for the Purpose. 
 (d) The Parties agree that the exchanged
Materials: 
 (1) shall at all times be manufactured in accordance with all applicable laws, rules and regulations, in accordance
with the terms of this Agreement and any applicable quality agreement or any further supply arrangements entered into by the Parties, and shall conform to any specifications agreed upon between the Parties; 

(2) shall be used in compliance with applicable Law; 

  
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 (3) shall not be used in animals intended to be kept as domestic pets; 

(4) shall not be transferred to a Third Party except if this is provided for and is done in accordance with this Agreement; and

 (5) shall not be reverse engineered or chemically analyzed, except if this is provided for in the applicable Research Plan.

 (e) THE MATERIALS SUPPLIED BY THE TRANSFERRING PARTY UNDER THIS SECTION 2.7.5 ARE SUPPLIED “AS IS” AND NOT FOR USE
IN HUMANS EXCEPT AS EXPRESSLY AGREED BY THE PARTIES IN WRITING, AND THE TRANSFERRING PARTY MAKES NO REPRESENTATIONS AND EXTENDS NO WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE, OR THAT THE USE OF THE MATERIALS DOES NOT INFRINGE ANY PATENT, COPYRIGHT, TRADEMARK, OR OTHER PROPRIETARY RIGHTS OF A THIRD PARTY. 
 (f) The Material Receiving Party assumes all liability for damages that may arise from its use, storage or disposal of the Materials. The Transferring Party shall not be liable to the Material Receiving
Party for any loss, claim or demand made by the Material Receiving Party, or made against the Material Receiving Party by any Third Party, due to or arising from the use of the Materials, except to the extent such loss, claim or demand is caused by
the gross negligence or willful misconduct of the Transferring Party. 
 ARTICLE 3 

POST-RESEARCH TERM ACTIVITIES; GSK DILIGENCE 
 3.1 Development and Commercialization. 
 3.1.1 GSK Activities. GSK,
either itself or by and through its Affiliates, Sublicensees or contractors, shall be solely responsible for all IND-enabling activities (except where GSK selects a Passed ROFO Target as a Selected Target in accordance with Section 2.2.4 and
EPIZYME has commenced a GLP Toxicology Study directed to such Selected Target, or activities leading up to such GLP Toxicology Study, at the time of such selection by GSK, in which cases GSK shall assume such responsibility upon such selection) and
for all other Development, manufacturing and Commercialization activities in connection with Licensed Compounds and Licensed Products, and all related Diagnostic Products, in the Field in the Territory. 

3.1.2 EPIZYME Activities. During the [**] year period after the end of the Research Term (the “Advisory Period”),
EPIZYME shall be available for, and shall provide consultation and advice to GSK as reasonably required with respect to GSK’s Development activities directed to Licensed Compounds and Licensed Products in the Field. Such consultation and
advice, if provided via teleconference or videoconference, shall be provided [**] to GSK and, if provided in person (other than at a JSC meeting) at GSK’s facilities as may be mutually agreed by the Parties, shall be provided subject to
GSK’s payment of EPIZYME’s travel expenses associated with the provision of such consultation and advice. 

  
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 3.2 Diligence. GSK shall use Commercially Reasonable Efforts (itself or through an
Affiliate or Sublicensee) to Develop, obtain Regulatory Approval for and Commercialize at least [**] with respect to each Selected Target in the [**] and the [**]. 
 3.3 Reports. On a [**] and Selected Target-by-Selected Target basis, following the end of the Research Term and continuing until [**], GSK shall provide EPIZYME with written reports summarizing in
reasonable detail (to the extent applicable) the material activities of GSK, its Affiliates and Sublicensees with respect to the then-current expected future plans and timetable for Development of Licensed Compounds, Licensed Products and Diagnostic
Products in the Field in the Territory for each Licensed Product directed to a Selected Target. If EPIZYME has any questions with respect to the information set forth in any report provided by GSK under this Section 3.3, EPIZYME shall direct
such questions to GSK’s Alliance Manager and GSK shall make reasonably available to EPIZYME appropriate technical or scientific personnel who are knowledgeable about the Development activities conducted by GSK to respond to such questions in a
timely manner, via teleconference, in person or such other mode of communication as the Parties may mutually agree. 
 ARTICLE
4 
 GOVERNANCE 
 4.1 Joint Steering Committee. As soon as possible after the Effective Date, the Parties shall establish a joint steering committee (the “JSC”) as more fully described in this
Section 4.1. The JSC shall have review, oversight and decision-making responsibilities for all activities performed under each Research Plan during the Research Term during the Collaboration, as more specifically provided herein. Each Party
agrees to keep the JSC informed of its progress and activities under the Collaboration. The JSC may establish Subcommittees as set forth in Section 4.2. 
 4.1.1 Membership. The JSC shall be comprised of [**] representatives (or such other number of representatives as the Parties may agree) from each of GSK and EPIZYME. Each Party may replace any or
all of its representatives on the JSC at any time upon written notice to the other Party in accordance with Section 13.7. Each representative of a Party shall have sufficient seniority and expertise in biotechnology and pharmaceutical drug
discovery and development to participate on the JSC. Each Party may, subject to the other Party’s prior approval, invite non-member representatives of such Party to attend meetings of the JSC as non-voting participants, subject to the
confidentiality obligations of Article 9. The Parties shall designate a chairperson (each, a “Chairperson”) to oversee the operation of the JSC, each such Chairperson to serve a twelve (12) month term. The right to name the
Chairperson shall alternate between the Parties, with [**] designating the first such Chairperson, who shall initially be [**]. 

4.1.2 Meetings. The first scheduled meeting of the JSC shall be held no later than [**] unless otherwise agreed by the Parties,
but in no event shall such JSC meeting be held later than [**] days after the Effective Date. Thereafter, prior to the expiration of the Research Term, the JSC shall meet in person at least [**], and more or less frequently as the Parties mutually
deem appropriate, on such dates and at such places and times as provided herein or as 

  
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the Parties shall agree. After the end of the Research Term, the JSC shall disband. Meetings of the JSC that are held in person shall alternate between the offices of the Parties, or such other
location as the Parties may agree. The members of the JSC also may convene or be polled or consulted from time to time by means of telecommunications, video conferences, electronic mail or correspondence, as deemed necessary or appropriate. Each
Party will bear all expenses it incurs in regard to participating in all meetings of the JSC, including all travel and living expenses. 
 4.1.3 Minutes. The Alliance Manager from the Party other than the Party of the Chairman, shall be responsible for preparing and circulating minutes of each meeting of the JSC, setting forth,
inter alia, an overview of the discussions at the meeting and a list of any actions, decisions or determinations approved by the JSC and a list of any issues to be resolved by the Executive Officers pursuant to Section 4.1.5. Such
minutes shall be effective only after approved by both Parties in writing. With the sole exception of specific items of the meeting minutes to which the members cannot agree and that are escalated to the Executive Officers as provided in
Section 4.1.5, definitive minutes of all JSC meetings shall be finalized no later than [**] days after the meeting to which the minutes pertain. If, at any time during the preparation and finalization of the JSC minutes, the Parties do not
agree on any issue with respect to the minutes, such issue shall be resolved by the escalation process set forth in Section 4.1.5. The decision resulting from the escalation process shall be recorded by the Alliance Manager in amended finalized
minutes for such meeting. 
 4.1.4 Responsibilities. The JSC shall perform the following functions, subject to the final
decision-making authority of the respective Parties as set forth in Section 4.1.5: 
 (a) review and monitor progress of
the Collaboration; 
 (b) determine whether Target Validation has been achieved with respect to each Selected Target;

 (c) review and approve changes to the Tractable Hit Criteria for each Selected Target; 

(d) determine whether the applicable Tractable Hit Criteria have been achieved with respect to any Compound; 

(e) review and approve changes to the Lead Candidate Criteria for each Selected Target; 

(f) determine whether the applicable Lead Candidate Criteria have been achieved with respect to any Compound; 

(g) review and approve changes to the Development Candidate Selection Criteria for each Selected Target; 

(h) determine whether the applicable Development Candidate Selection Criteria have been achieved with respect to any Compound;

  
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 (i) serve as a forum for exchange of information and to facilitate discussions regarding
the conduct of the Collaboration and the Development of Licensed Compounds, Licensed Products and Diagnostic Products hereunder; 
 (j) discuss and attempt to resolve any deadlocked issues submitted to it in accordance with the procedures established in Section 4.1.5; 

(k) review and approve Research Plans submitted by the JPT; 
 (l) review and discuss ROFO Packages; 
 (m) such other responsibilities as may be
assigned to the JSC pursuant to this Agreement or as may be mutually agreed by the Parties from time to time; and 
 (n) review
and monitor the transfer and delivery of Know-How and material to GSK that is provided for under Section 5.5. 
 For clarity, the JSC shall
not have any authority beyond the specific matters set forth in this Section 4.1.4, and in particular shall not have any power to amend or modify the terms of this Agreement. In any case where a matter within the JSC’s authority arises,
the JSC shall convene a meeting and consider such matter within [**] days after the matter is first brought to the JSC’s attention, or, if earlier, at the next regularly-scheduled JSC meeting. 

4.1.5 Decisions. Except as otherwise provided herein, all decisions of the JSC shall be made by consensus, with each Party having
one vote. If the JSC cannot agree on a matter within the JSC’s authority within [**] days after it has met and attempted to reach such decision, then, either Party may, by written notice to the other, have such issue referred to the Executive
Officers for resolution. The Parties’ respective Executive Officers shall meet within [**] Business Days after such matter is referred to them, and shall negotiate in good faith to resolve the matter. If the Executive Officers are unable to
resolve the matter within [**] days after the matter is referred to them, then (a) EPIZYME shall have final decision-making authority with respect to any matters arising with respect to its day-to-day implementation of the Research Plan during
the Research Term, and (b) GSK shall have final decision-making authority with respect to all other matters arising in the conduct of the Collaboration, in each case subject to Section 4.1.6 below. 

4.1.6 Limitations on Decision-Making Authority. The foregoing provisions of Section 4.1.5 notwithstanding, neither Party
shall have the right to exercise its final decision-making authority to unilaterally: (a) determine that it has fulfilled any obligations under this Agreement or that the other Party has breached any obligation under this Agreement;
(b) subject to Section 4.1.7, determine that milestone events required for the payment of milestone payments have or have not occurred; (c) make a decision that is expressly stated to require the mutual agreement of the Parties; or
(d) otherwise expand its rights or reduce its obligations under this Agreement, including by making any unilateral changes to the Tractable Hit Criteria, the Lead Candidate Criteria or the Development Candidate Selection Criteria. 

  
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 4.1.7 Disagreements Regarding Achievement of Certain Milestone Events. In the event
of any disagreement between the Parties regarding the achievement of a milestone event set forth in Section 6.4 or Section 6.5 based on the achievement of Target Validation, Tractable Hit Criteria, Lead Candidate Criteria or Development
Candidate Selection Criteria, EPIZYME shall, at GSK’s option, either (a) continue to conduct research activities during the Research Term directed to achieving the disputed milestone event to GSK’s reasonable satisfaction or
(b) progress to activities with respect to the applicable Selected Target that are specified in the applicable Research Plan to be conducted following the achievement of such milestone event; provided that, if GSK requests that
EPIZYME progress to such later stage activities (or if GSK itself progresses to Development activities that follow the disputed milestone event), then the disputed milestone event shall be deemed achieved once (i) EPIZYME or GSK, as applicable,
undertakes [**] percent ([**]%) of the [**] set forth in the Research Plan for such later stage activities, or (ii) in the case of activities undertaken by GSK with respect to Development activities, GSK undertakes substantial activities not
set forth in the Research Plan and that are designed to [**] for the applicable Licensed Compound. 
 4.2
Subcommittee(s). From time to time, the JSC may establish subcommittees to oversee particular projects or activities, as it deems necessary or advisable (each, a “Subcommittee”). Each Subcommittee shall consist of such number
of members as the JSC determines is appropriate from time to time. Such members shall be individuals with expertise and responsibilities in the relevant areas such as high-throughput screening, protein generation, non-clinical Development,
pharmacology, clinical Development, patents, process sciences, manufacturing, quality, regulatory affairs, product Development or product Commercialization, as applicable to the stage of the project or activity. 

4.3 Joint Project Team. As soon as possible after the Effective Date, the Parties shall establish a joint project team (the
“Joint Project Team” or “JPT”). The JPT shall be comprised of an equal number of representatives from each of GSK and EPIZYME with the appropriate scientific expertise with respect to the conduct of the Research
Plans and shall meet on a [**]basis (or more or less frequently as agreed by the Parties) at EPIZYME’s facilities or via teleconference at such times as may be agreed by the Parties during the Research Term. The first scheduled meeting of the
JPT shall be held as soon as possible after the Effective Date, but unless otherwise agreed by the Parties, no later than [**]. The JPT will report to the JSC and will be responsible for the day-to-day management of the conduct of the Research Plans
including overseeing the conduct of experiments and reviewing data resulting from such experiments as set forth in the Research Plans, proposing amendments to the Research Plans, developing new Research Plans when Available Targets are chosen by GSK
as Selected Targets, exchanging information regarding the Parties’ activities conducted during the Collaboration, and making recommendations to the JSC with respect to whether Compounds achieve the Tractable Hit Criteria, Lead Candidate
Criteria or Development Candidate Criteria. Notwithstanding anything in this Agreement to the contrary, EPIZYME shall have the right to [**] of any Compound prior to such Compound’s achievement of the Lead Candidate Criteria, whether [**] at
any JPT meeting, in any report or otherwise. All decisions of the JPT on matters for which it has responsibility shall be made unanimously. In the event that the JPT is unable to reach a unanimous decision within [**] days after it has met and
attempted to reach such decision, then either Party may, by written notice to the other, have such issue submitted to the JSC for resolution in accordance with Section 4.1.5. Each Party will bear all expenses it incurs in regard to
participating in all meetings of the JPT, including all travel and living expenses. 

  
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 4.4 Patent Liaisons. Promptly (but no later than [**] days) after the Effective Date,
the Parties shall each designate representative(s) to consult with the other Party’s representative(s) with respect to Patent prosecution and enforcement matters (the “Patent Liaisons”) as more fully described in this
Section 4.4. The Patent Liaisons shall discuss, at such times, places and frequencies as either Patent Liaison determines is necessary, material issues and provide input to each other regarding the prosecution, maintenance, enforcement or
defense of Collaboration IP, EPIZYME IP, EPIZYME Diagnostic IP, GSK IP and Joint IP. The Patent Liaisons shall be responsible for coordinating the implementation of each Party’s strategies for the protection of the foregoing intellectual
property rights related to Licensed Compounds and EPIZYME Compounds, as applicable; provided, that such strategy for both Parties shall require the filing and prosecution of [**] with respect to [**] reasonably possible, with the [**] (the foregoing
referred to herein as the “Patent Strategy”). All final decisions related to the prosecution, maintenance, enforcement or defense of any Collaboration IP, EPIZYME IP, EPIZYME Diagnostic IP, GSK IP and Joint IP shall be made by the
Party with the right to control such prosecution, maintenance, enforcement or defense, as applicable, as set forth in Article 8. 
 4.5 Alliance Managers. Promptly after the Effective Date, each Party shall appoint an individual to act as alliance manager for such Party (each, an “Alliance Manager”). The
Alliance Managers shall be the primary point of contact for the Parties regarding the activities contemplated by this Agreement and shall facilitate all such activities hereunder, including preparing and finalizing minutes of the JSC meetings. The
Alliance Managers shall attend all meetings of the JSC and shall be responsible for assisting the JSC in performing its oversight responsibilities. The name and contact information for each Party’s Alliance Manager, as well as any
replacement(s) chosen by EPIZYME or GSK, in their sole discretion, from time to time, shall be promptly provided to the other Party in accordance with Section 13.7. 
 ARTICLE 5 
 LICENSE GRANTS 

5.1 License Grants To GSK. Subject to the terms and conditions of this Agreement: 

5.1.1 Licensed Products. Commencing upon each Target becoming a Selected Target and continuing during the remainder of the Term
while such Target continues to be a Selected Target, EPIZYME hereby grants to GSK an exclusive right and license (even as to EPIZYME and its Affiliates) in the Field in the Territory, with the right to grant sublicenses (subject to
Section 5.1.3), under the EPIZYME IP, EPIZYME Diagnostic IP, Collaboration IP Controlled by EPIZYME, and EPIZYME’s interest in the Joint IP, to research, Develop, make, have made, use, offer for sale, sell, import and otherwise
Commercialize any and all Licensed Compounds and Licensed Products, in each case directed to such Selected Target. 
 5.1.2
Diagnostic Products. Commencing upon each Target becoming a Selected Target and continuing during the remainder of the Term while such Target continues to be a Selected Target, EPIZYME hereby grants to GSK an exclusive right and license (even
as to 

  
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EPIZYME and its Affiliates) in the Field in the Territory, with the right to grant sublicenses (subject to Section 5.1.3), under EPIZYME Diagnostic IP, Collaboration IP Controlled by
EPIZYME, and EPIZYME’s interest in the Joint IP, to research, Develop, make, have made, use, offer for sale, sell, import and otherwise Commercialize Diagnostic Products related to Licensed Products directed to such Selected Targets.

 5.1.3 GSK’s Sublicensing Rights. GSK shall have the right to grant sublicenses under the rights granted to it
under Sections 5.1.1 and 5.1.2 without the prior written consent of EPIZYME to any of GSK’s Affiliates and to Third Party service providers engaged by GSK in the ordinary course of business. GSK shall also have the right to grant sublicenses
under the rights granted to it under Sections 5.1.1 and 5.1.2, without the prior written consent of EPIZYME, to any Third Party; provided however that GSK shall provide EPIZYME with a fully-executed copy of any agreement
(redacted as necessary to protect confidential or commercially sensitive information) reflecting any such sublicense promptly after the execution thereof. Each sublicense granted by GSK under this Section 5.1.3 shall be subject to and
consistent with the terms and conditions of this Agreement. GSK shall remain primarily liable for, and shall guarantee the performance of, its Affiliates and Sublicensees with respect to any sublicense granted pursuant to this Section 5.1.3.

 5.2 License Grants to EPIZYME. Subject to the terms and conditions of this Agreement: 

5.2.1 Research Grant and Grant-Back to EPIZYME. On a Selected Target by Selected Target basis, during the Research Term, GSK
hereby grants to EPIZYME the non-exclusive, royalty-free license in the Field in the Territory, with the right to grant sublicenses (subject to Section 5.2.3), under (a) GSK IP that GSK determines in its sole discretion is necessary for
the conduct of the Collaboration, (b) GSK’s rights under the licenses granted to GSK by EPIZYME under Sections 5.1.1 and 5.1.2, and (c) Collaboration IP Controlled by GSK and GSK’s interest in the Joint IP, in each case of
(a) through (c) (inclusive) solely to permit EPIZYME to conduct its activities with respect to such Selected Target as contemplated under the applicable Research Plans as part of the Collaboration in accordance with the terms of this
Agreement. 
 5.2.2 Dropped Targets. On a Dropped Target-by-Dropped Target basis, GSK hereby grants to EPIZYME a license
in the Field in the Territory, with the right to grant sublicenses (subject to Section 5.2.3), under GSK IP directed to such Dropped Target, Collaboration IP Controlled by GSK, and GSK’s interest in the Joint IP, in each case to the extent
used in connection with the Selected Target that became a Dropped Target, to research, Develop, make, have made, use, sell, offer for sale and import EPIZYME Compounds and EPIZYME Products directed to such Dropped Target, and all related EPIZYME
Diagnostic Products. Such license to EPIZYME shall be co-exclusive (with GSK and its Affiliates); provided however that, such license shall be exclusive (even as to GSK and its Affiliates) (a) with respect to Collaboration
IP Controlled by GSK and GSK’s interest in Joint IP, in each case that claim the composition of matter or method of use of any EPIZYME Compound or EPIZYME Product directed to such Dropped Target, and (b) with respect to Diagnostic IP
Controlled by GSK that Covers the Development, manufacture or Commercialization of EPIZYME Diagnostic Products that are related to any EPIZYME Compound or EPIZYME Product for which EPIZYME is granted an exclusive license under the foregoing clause
(a). 

  
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 5.2.3 EPIZYME’s Sublicensing Rights. Subject to Section 7.1.2(b), EPIZYME
may grant sublicenses under the rights granted to it under Section 5.2.1 without the prior written consent of GSK to EPIZYME Affiliates and Third Party service providers engaged by EPIZYME in the ordinary course of business (for example and
without limitation, to synthesize Compounds). EPIZYME may also grant sublicenses under the rights granted to it under Section 5.2.2, without the prior written consent of GSK, to any EPIZYME Affiliate or Third Party; provided
however that EPIZYME shall provide GSK with written notice of any such sublicense. Each sublicense granted by EPIZYME under this Section 5.2.3 shall be subject to and consistent with the terms and conditions of this Agreement.
EPIZYME shall remain primarily liable for, and shall guarantee the performance of, its Affiliates and Sublicensees with respect to any sublicense granted pursuant to this Section 5.2.3. EPIZYME shall require (by entering into written agreements
implementing the terms of this Section 5.2.3) that its employees and Affiliates, and EPIZYME shall use Commercially Reasonable Efforts to require that its Third Party service providers, sublicensees and subcontractors, execute any assignment or
other documents as may be reasonably required for the purpose of vesting in EPIZYME all license and other intellectual property rights and moral rights arising from the activities conducted by such employees, Affiliates, Third Party service
providers, sublicensees and subcontractors on behalf of EPIZYME under this Agreement, to the extent necessary for EPIZYME to grant to GSK the rights and licenses granted to GSK under this Agreement. 

5.3 Rights Retained by the Parties. For purposes of clarity, each Party retains the right under Know-How and Patents Controlled by
such Party to the extent necessary to exercise its rights and perform its obligations under this Agreement, and any rights of EPIZYME or GSK, as the case may be, not expressly granted to the other Party pursuant to this Agreement shall be retained
by such Party. In addition, subject to the exclusivity obligations set forth in Section 7.1, EPIZYME retains the right, under Patents and Know-How Controlled by EPIZYME, including its interest in Joint IP, to perform ongoing platform discovery
activities. 
 5.4 Section 365(n) of the Bankruptcy Code. All rights and licenses granted pursuant to any section of
this Agreement are rights and licenses to “intellectual property” (as defined in Section 101(35A) of title 11 of the United States Code (the “Bankruptcy Code”)). Each Party shall retain and may fully exercise all of
its rights and elections under the Bankruptcy Code. 
 5.5 Technical Transfer and Disclosure of Know-How. On a Selected
Target by Selected Target basis, promptly following declaration by the JSC that a Licensed Compound has met the Development Candidate Criteria, to the extent not previously transferred and delivered to GSK, EPIZYME shall transfer and deliver to GSK,
at EPIZYME’s cost (in order to enable GSK to practice under the licenses but without expanding the licenses granted to GSK under Section 5.1), EPIZYME Know-How and Collaboration Know-How (including material) in its Control relating to such
Selected Target and all Licensed Compounds and Licensed Products directed to such Selected Target and Collaboration Know-How in its Control relating to Diagnostic Products relating to such Licensed Products, in each case as is reasonably necessary
to enable GSK to Develop, manufacture and Commercialize the Licensed Compounds, Licensed Products and 

  
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Diagnostic Products as contemplated under this Agreement. Without limiting the foregoing, EPIZYME shall use Commercially Reasonable Efforts with respect to those activities for which it is
responsible to facilitate orderly transition and uninterrupted Development, manufacture and Commercialization of all such Licensed Compounds and Licensed Products directed to such Selected Target and all Diagnostic Products relating to such Licensed
Products. After the transfer described above, EPIZYME shall use Commercially Reasonable Efforts, upon the reasonable request of GSK, to cooperate with GSK to provide GSK with Know-How, at EPIZYME’s cost, to the extent not previously transferred
and delivered to GSK, to which EPIZYME obtains Control as it may be developed, identified or exist and to which GSK has a license under Section 5.1 of this Agreement. For purposes of clarity, to the extent of early termination of one or more
Selected Targets pursuant to Section 12.3.1 for EPIZYME’s material breach, then (a) with respect to any Selected Target which has not been terminated, EPIZYME shall continue to comply with this Section 5.5 to the extent
applicable, and (b) with respect to Selected Targets which have been terminated, if the termination occurs during the Research Term, EPIZYME’s obligations under the Research Plans applicable to such terminated Selected Targets shall
terminate and EPIZYME shall cooperate with GSK to promptly provide GSK with any and all Know-How in its Control as of the effective date of such termination that would be reasonably necessary for GSK to continue its performance under this Agreement
in relation to the terminated Selected Targets, to the extent such has not already been provided to GSK and without expanding the licenses granted to GSK pursuant to Section 5.1 (as contemplated in Section 12.5.2). 

ARTICLE 6 

FINANCIAL TERMS; EQUITY OPTION 
 6.1 Upfront Fee. In partial consideration for the licenses granted to GSK hereunder, GSK shall pay EPIZYME a non-refundable, non-creditable payment of Twenty Million Dollars ($20,000,000). Such
payment shall be payable by wire transfer of immediately available funds in accordance with wire transfer instructions of EPIZYME provided in writing to GSK on or prior to the Effective Date. Such payment shall be made within [**] Business Days
after GSK’s receipt of an invoice from EPIZYME on or after the Effective Date, which invoice shall be sent in PDF format to [**] with a copy to [**]. 
 6.2 Research Funding. GSK shall make non-refundable, non-creditable payments (the “Research Payments”) to EPIZYME for activities to be undertaken by EPIZYME under the Research
Plans as follows: 
 (a) Commencing on the first
(1st) anniversary of the Effective Date and the date
that is the first day of each Calendar Quarter after the first anniversary of the Effective Date, GSK shall pay equal Calendar Quarterly installments of Seven Hundred Fifty Thousand Dollars ($750,000.00) to EPIZYME for eight (8) consecutive
Calendar Quarters (with the first such Calendar Quarterly installment being due on the first anniversary of the Effective Date). For illustrative purposes only, if the Effective Date of the Agreement is January 8, 2011, then the first Research
Payment would become due on January 8, 2012, and the second Research Payment would become due on April 1, 2012. 

  
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 (b) Commencing on the third (3rd) anniversary of the Effective Date and on the date that is the
first day of each Calendar Quarter of the fourth
(4th) year of the Research Term, GSK shall pay to
EPIZYME advance Calendar Quarterly installments constituting the portion of the total FTE Costs and Out-of-Pocket Costs budgeted for such Calendar Quarter under the Research Plans pursuant to Section 2.3.3 (with the first such Calendar
Quarterly installment being due on the third
(3rd) anniversary of the Effective Date). Within [**]
days following the end of the Research Term, the Parties shall conduct a reconciliation of actual FTE Costs and Out-of-Pocket Costs incurred by EPIZYME for activities conducted during the fourth (4th) year of the Research Term against the amount budgeted for such
fourth (4th) year, and the Parties shall true up
actual FTE Costs and Out-of-Pocket Costs to budgeted amounts, within [**] percent ([**]%) of the amount budgeted, for the fourth (4th) year of the Research Term through an appropriate reconciliation payment so that GSK’s research funding
payments to EPIZYME with respect to the fourth
(4th) year of the Research Term, net of such
reconciliation payment, equal the actual FTE Costs and Out-of-Pocket Costs incurred by EPIZYME for activities conducted during the fourth (4th) year of the Research Term (but not more than [**]% of the budgeted amount). If EPIZYME determines it cannot
complete the activities set forth in the Research Plans for the fourth (4th) year of the Research Term within [**] percent ([**]%) of the budgeted amounts, EPIZYME shall promptly notify GSK and, provided that such inability is not a consequence of EPIZYME’s failure to
use Commercially Reasonable Efforts to complete such activities within such agreed budget, the Parties shall discuss and mutually agree on adjustments to the scope of activities or to the budget, or both, such that EPIZYME can complete the agreed
activities within the agreed budget constraint. 
 (c) The Research Payments shall be used by EPIZYME solely to cover the costs
of the conduct of the Research Plans that are incurred after the Effective Date. No later than [**] days after the end of each Calendar Year during which EPIZYME is conducting activities under the Collaboration, EPIZYME will submit to GSK reasonable
documentation as may be requested by GSK, setting forth the costs incurred for such activities and the funds from the Research Payments that were applied to such costs for the preceding Calendar Year. 

(d) GSK shall make the Research Payments within [**] days after receipt of an invoice from EPIZYME, which invoice shall be sent in PDF
format to [**] with a copy to [**] (or such other email address(es) as may be notified to EPIZYME by GSK), but GSK shall not be required to make such payments earlier than the scheduled dates of payment set forth above. 

6.3 Equity Option. GSK shall have the option, but shall not be required, to acquire up to ten percent (10%), in its discretion, of
the securities issued in EPIZYME’s next Qualified Financing (as defined below) at the closing of such Qualified Financing and pursuant to the definitive agreements for such Qualified Financing (including customary limitations applicable to
strategic investors that are consistent with limitations imposed on strategic investors in EPIZYME’s prior financings) as negotiated by and among EPIZYME and the lead investors in such Qualified Financing. Notwithstanding the foregoing, in
no event shall GSK exercise such participation right to the extent that it would own more than 19.9% of EPIZYME’s outstanding capital stock upon the closing of such Qualified Financing (treating for this purpose as outstanding all shares of
EPIZYME common stock issuable upon exercise of options outstanding 

  
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immediately prior to such issue or upon conversion or exchange of convertible securities (including preferred stock) outstanding and assuming exercise of any outstanding options
therefor). For purposes of this Agreement, “Qualified Financing” means the issuance of convertible preferred stock or other securities by EPIZYME after the Effective Date in exchange for a payment of cash in a financing round
led by bona fide venture capital institutional investors (i.e., excluding investors that are controlled by or under common control with an operating company in the life sciences space), where at least one (1) such bona fide venture
capital institutional investor is a new investor, in which EPIZYME raises gross proceeds of at least [**] Dollars ($[**]). For purposes of clarity, the option set forth in this Section 6.3 to acquire EPIZYME securities shall only apply to
EPIZYME’s next Qualified Financing and shall not apply to any subsequent financings. 
 6.4 Target Validation and
Tractable Hit Milestone Payments. For each of the second and third Selected Targets (but not with respect to the first Selected Target), GSK shall make a non-refundable, non-creditable milestone payment to EPIZYME of Two Million Dollars
($2,000,000) upon the achievement of Target Validation with respect to such Selected Target and GSK shall make a non-refundable, non-creditable milestone payment to EPIZYME of Two Million Dollars ($2,000,000) upon the identification of a Tractable
Hit with respect to such Selected Target. For the avoidance of doubt, (x) none of the milestone payments specified in this Section 6.4 shall be payable more than [**] in aggregate, and none of such milestone payments shall be payable more
than one time with respect to any applicable Selected Target, (y) the milestone payments specified in this Section 6.4 shall be payable with respect to each of the second and third Selected Targets with respect to which the milestones are
met regardless of whether or not any prior Selected Target(s) have been dropped and (z) if Target Validation has been achieved or a Tractable Hit has been identified prior to the selection of an applicable Selected Target, the milestone payment
specified in this Section 6.4 for the achievement of Target Validation or identification of a Tractable Hit, as applicable, with respect to such Selected Target shall be payable upon the selection of such Selected Target. 

6.5 Development Milestones. 
 6.5.1 GSK shall make the non-refundable, non-creditable milestone payments to EPIZYME that are set forth below upon the first achievement by EPIZYME, GSK, or their respective Affiliates or Sublicensees of
the milestone events set forth below with respect to each Selected Target, on a Selected Target-by-Selected Target basis (except as otherwise set forth below). 
  

					
	 Milestone Event
 (For each Selected Target)
	  	Milestone
Payments
(in $
[**])	 
	 [**]
	  	 	[**	] 
	 [**]
	  	 	[**	] 
	 [**]
	  	 	[**	] 
	 [**]
	  	 	[**	] 
	 [**]
	  	 	[**	] 

  
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	 Milestone Event
 (For each Selected Target)
	  	Milestone
Payments
(in $
[**])	 
	 [**]
	  	 	[**	] 
	 [**]
	  	 	[**	] 
	 [**]
	  	 	[**	] 
	 [**]
	  	 	[**	] 
	 [**]
	  	 	[**	] 
	 [**]
	  	 	[**	] 
	 [**]
	  	 	[**	] 

 6.5.2 If, upon achievement of a particular milestone event set forth in the table in Section 6.5.1,
any of the applicable previous milestone payments for milestone events [**] above set forth in the table in Section 6.5.1 has not been paid for such Selected Target, then such milestone payment(s) shall be payable concurrently with the payment
for such subsequent achievement; provided that, if the applicable milestone payment that has not previously been paid is for milestone event [**], then the foregoing provisions of this sentence shall only require the payment of such
missed milestone payment when the payment for the subsequent achievement relates to the third Selected Target. For the avoidance of doubt, nothing in this Section 6.5.2 shall require the payment of a milestone payment with respect to a Selected
Target that is specified in Section 6.5.1 not to be payable with respect to such Selected Target. 
 6.5.3 Upon achievement
by or on behalf of EPIZYME, its Affiliates or Sublicensees of a milestone event set forth in Section 6.4, in this Section 6.5 or in Section 6.6, GSK shall pay EPIZYME the corresponding milestone payment within [**] days after receipt
of an invoice for the milestone payment from EPIZYME. Upon achievement by or on behalf of GSK, its Affiliates or Sublicensees of a milestone event, GSK shall promptly (but in no event more than [**] Business Days after achievement thereof) notify
EPIZYME of such achievement, and GSK shall pay EPIZYME the corresponding milestone payment within [**] days after receipt of an invoice for the milestone payment from EPIZYME. Invoices shall be sent in PDF format to GSK’s Alliance Manager and
[**] with a copy to [**] (or such other email address(es) as may be notified to EPIZYME by GSK). 
 6.5.4 If GSK chooses as a
Selected Target any Passed ROFO Target, then upon such selection by GSK, GSK would pay any milestone payments set forth in this Section 6.5 or in Section 6.4 above that have been previously achieved by a Compound directed to such Passed
ROFO Target; provided however that, the milestone payment set forth in Section 6.4 above would only be paid upon such selection by GSK if the milestone payment set forth in Section 6.4 above had not then previously
been paid with respect to [**] other Selected Targets. 
 6.6 Additional Milestone for Diagnostic Products. GSK shall
make a non-refundable, non-creditable milestone payment to EPIZYME of [**] Dollars ($[**]) upon the [**]. 

  
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 6.7 Sales Milestones. As to each of the sales milestone events set forth below, GSK
shall pay EPIZYME the non-refundable, non-creditable sales milestone payments indicated below upon the first achievement by GSK, its Affiliates or Sublicensees of the success milestone events set forth below with respect to each Selected Target, on
a Selected Target-by-Selected Target basis. 
  

					
	 Sales Milestone Event

(For Licensed Products directed to a Selected Target)
	  	Milestone
Payment
(in $
[**])	 
	 First Calendar Year in which aggregate world-wide Net Sales of Licensed Product(s) directed to such Selected Target are greater
than or equal to $[**]
	  	 	[**	] 
		
	 First Calendar Year in which aggregate world-wide Net Sales of Licensed Product(s) directed to such Selected Target are greater
than or equal to $[**]
	  	 	[**	] 
		
	 First Calendar Year in which aggregate world-wide Net Sales of Licensed Product(s) directed to such Selected Target are greater
than or equal to $[**]
	  	 	[**	] 

 Upon achievement by or on behalf of GSK, its Affiliates or Sublicensees of a sales milestone event set
forth in this Section 6.7, GSK shall promptly (but in no event later than the date on which the royalty report for the Calendar Quarter in which such achievement occurs is due pursuant to Section 6.10.1) notify EPIZYME of such achievement,
and GSK shall pay EPIZYME the corresponding sales milestone payment within [**] days after receipt of an invoice for the milestone payment from EPIZYME. Such invoice shall be sent to GSK’s Alliance Manager and [**] with a copy to [**] (or such
other email address(es) as may be notified to EPIZYME by GSK). For the avoidance of doubt, more than one of the foregoing sales milestone payments may be earned and become payable with respect to Licensed Products directed to any given Selected
Target in the same Calendar Year based on aggregate world-wide Net Sales of Licensed Product(s) directed to such Selected Target during such Calendar Year. 

  
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 6.8 Licensed Product Royalties. 

6.8.1 Licensed Product Royalties. GSK shall pay EPIZYME incremental royalties on worldwide Annual Net Sales, on a Licensed
Product-by-Licensed Product basis, at the royalty rates set forth in the table below: 
  

					
	 Worldwide Annual Net Sales
	  	Incremental
Royalty Rates	 
	 Portion up to but not including $[**]
	  	 	[**	]% 
		
	 Portion equal to or greater than $[**] up to but not including $[**]
	  	 	[**	]% 
		
	 Portion equal to or greater than $[**]
	  	 	[**	]% 

 For example, if worldwide Annual Net Sales of a Licensed Product were $[**], the royalties payable with respect to such
Annual Net Sales, subject to adjustment as set forth in this Section 6.8 below, would be [**]. 
 Notwithstanding the foregoing, with
respect to Licensed Products containing Licensed Compounds that are first identified by screening a GSK compound library at any time during the Research Term (provided that the Parties have mutually agreed to conduct such screening),
the foregoing royalty rates shall be reduced to [**] percent ([**]%) of the otherwise applicable royalty rates. 
 6.8.2
Royalty Term and Adjustments. 
 (a) GSK’s royalty obligations to EPIZYME under this Section 6.8 shall
commence on a country-by-country and Licensed Product-by-Licensed Product basis on the date of First Commercial Sale by GSK, its Affiliates or Sublicensees to an unaffiliated Third Party of the relevant Licensed Product in the relevant country and
shall expire on a country-by-country basis and Licensed Product-by-Licensed Product basis upon the later of the following (the “Royalty Term” for each Licensed Product), as applicable: 

(i) the expiration of Patent-Based Exclusivity with respect to such Licensed Product in such country; or 

(ii) the [**] anniversary of the First Commercial Sale of such Licensed Product in such country by GSK, its Affiliates or Sublicensees.

 (b) The foregoing provisions of this Section 6.8 notwithstanding, the royalties payable with respect to Net Sales of
Licensed Products shall be reduced, on a Licensed Product-by-Licensed Product and country-by-country basis, to [**] percent ([**]%) of the amounts otherwise payable pursuant to 6.8.1 during any portion of the Royalty Term when Patent-Based
Exclusivity does not apply to such Licensed Product in such country (hereinafter, the “Know-How Royalty”). 

6.8.3 Royalty Reduction for Comparable Third Party Product Competition. If, on a Licensed Product-by-Licensed Product,
country-by-country and Calendar Quarter-by-Calendar Quarter basis, Comparable Third Party Product Competition is present with respect to such Licensed Product in such country during such Calendar Quarter, then the royalties payable

  
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with respect to Net Sales of such Licensed Product pursuant to Sections 6.8.1 and 6.8.2 in such country during such Calendar Quarter shall be reduced to [**] percent ([**]%) of the royalties
otherwise payable pursuant to Sections 6.8.1 and 6.8.2. 
 6.8.4 Third Party Payments. GSK shall be entitled to credit
against the royalties due to EPIZYME upon Net Sales of a Licensed Product in a country an amount equal to [**]percent ([**]%) of the total royalties paid by GSK to Third Parties with respect to license rights to Third Party Patents or Know-How
necessary for the manufacture, use, offer for sale, sale or importation of such Licensed Product in such country; provided however that, all such credits pursuant to this Section 6.8.4 shall not reduce the royalties payable
to EPIZYME with respect to any Licensed Product in any country to less than [**] percent ([**]%) of the royalties otherwise due to EPIZYME pursuant to Sections 6.8.1, 6.8.2, and 6.8.3; and provided further that, GSK shall have
the right to carry forward for application against royalties payable to EPIZYME with respect to Net Sales of such Licensed Product in such country in future periods any amount that is not so credited due to the limitation in the immediately
preceding proviso. In the event EPIZYME enters into a Patent or Know-How license with a Third Party that is necessary for its activities and necessary for the manufacture, use, offer for sale, sale or importation of a Licensed Product in a country
after the Effective Date, (it being understood that EPIZYME is not a party to any such relevant Third Party licenses as of the Effective Date), under which EPIZYME is entitled to grant a sublicense to GSK, GSK will have the right to obtain such
sublicense from EPIZYME; provided however that, (a) if GSK elects to obtain such sublicense, GSK would pay one hundred percent (100%) of the amounts payable to the Third Party on account of such sublicense (either
directly to the Third Party licensor or to EPIZYME, as the Parties shall reasonably agree with the goal of ensuring timely payment to the Third Party) and GSK shall be entitled to credit against the royalties due to EPIZYME upon Net Sales of such
Licensed Product in such country an amount equal to [**] percent ([**]%) of the amounts paid by GSK (either directly or indirectly through EPIZYME) to such Third Party with respect to such license rights for such Licensed Product in such country,
subject to the same limitations described in the provisos at the end of the immediately preceding sentence, and (b) if GSK does not pay one hundred percent (100%) of the amounts payable to such Third Party on account of such sublicense to
GSK, such Third Party Patent or Know-How shall be excluded from the licenses granted to GSK hereunder (i.e., if GSK does not pay such amounts with respect to sublicenses that would otherwise be granted to GSK under Third Party license(s) entered
into by EPIZYME, the corresponding license rights shall not be sublicensed to GSK and EPIZYME shall be deemed not to Control such licensed intellectual property for purposes of the licenses granted to GSK hereunder). 

6.9 Royalties for EPIZYME Products. 
 6.9.1 Royalty Rates. EPIZYME shall pay GSK incremental royalties on worldwide Annual Net Sales of EPIZYME Products directed to Eligible Dropped Targets (each, a “Royalty-Bearing EPIZYME
Product”) on a Royalty-Bearing EPIZYME Product-by- Royalty-Bearing EPIZYME Product basis, at the royalty rates set forth in the table below: 
  

					
	 Worldwide Annual Net Sales
	  	Incremental
Royalty Rates	 
	 Portion up to but not including $[**]
	  	 	[**	]% 
		
	 Portion equal to or greater than $[**] up to but not including $[**]
	  	 	[**	]% 
		
	 Portion equal to or greater than $[**]
	  	 	[**	]% 

  
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 6.9.2 Royalty Adjustments and Royalty Term for Royalty-Bearing EPIZYME Products. The
provisions of Sections 6.8.2, 6.8.3, and 6.8.4 shall apply, mutatis mutandis, to EPIZYME’s obligations to pay royalties under Section 6.9.1, with all references to “GSK” in Sections 6.8.2, 6.8.3, and 6.8.4 replaced by
“EPIZYME,” all references to “EPIZYME” in Sections 6.8.2, 6.8.3, and 6.8.4 replaced by “GSK” and all references to “Licensed Compound” or “Licensed Product” in Sections 6.8.2, 6.8.3, and 6.8.4
replaced with “EPIZYME Compound” or “Royalty-Bearing EPIZYME Product.” 
 6.10 Reports; Sales Milestones;
Royalty Payments. 
 6.10.1 Until the expiration of all applicable Royalty Terms and sales milestone obligations under this
Article 6, each Party agrees to make written reports to the other Party within [**] days after the end of each Calendar Quarter covering sales of Licensed Products or Royalty-Bearing EPIZYME Products, as applicable, on a product-by-product and
country-by-country basis in the Territory by such Party, its Affiliates and Sublicensees during such Calendar Quarter. The information contained in each report under this Section 6.10 shall be considered Confidential Information of the Party
providing the report. 
 6.10.2 Each such written report shall provide Net Sales by country by Licensed Product or
Royalty-Bearing EPIZYME Product, as applicable, for the period in question, adjustments (if any) made pursuant to Sections 6.8.2, 6.8.3, 6.8.4 and 6.9.2 and a calculation of royalties due. In addition to the foregoing, each such written report
provided by GSK to EPIZYME shall contain a calculation of sales milestones due, if any. 
 6.10.3 Concurrent with the delivery
of each such report, the Party delivering such report shall make the royalty payment due the other Party under Article 6 for the Calendar Quarter covered by such report. In the case of transfers or sales of any Licensed Product or Royalty-Bearing
EPIZYME Product, as applicable, between the royalty-paying Party and an Affiliate or Sublicensee of such Party, a royalty shall be payable only with respect to the sale of such Licensed Product or Royalty-Bearing EPIZYME Product to an independent
Third Party that is not an Affiliate or Sublicensee of the seller. 
 6.11 Methods of Payments. All payments due from one
Party (the “Payor”) to the other Party (the “Payee”) under this Agreement shall be paid in Dollars by wire transfer to a bank in the United States designated in writing by the Payee. 

  
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 6.12 Accounting. 

6.12.1 Payor agrees to keep, and to require its Affiliates and Sublicensees to keep, full, clear and accurate records for a minimum
period of [**] years after the relevant payment is owed pursuant to this Agreement, setting forth the sales and other disposition of Licensed Products and Royalty-Bearing EPIZYME Products sold or otherwise disposed of in sufficient detail to enable
royalties and compensation payable to the Payee hereunder to be determined. 
 6.12.2 Payor further agrees, upon not less than
[**] days prior written notice, to permit, and to require its Affiliates and Sublicensees to permit, the books and records relating to such Licensed Product or Royalty-Bearing EPIZYME Product to be examined by an independent accounting firm selected
by Payee and reasonably acceptable to Payor for the purpose of verifying reports provided by Payor under this Article 6. Such audit shall not be performed more frequently than [**] in any twelve (12)-month period, and shall be conducted under
appropriate confidentiality provisions, for the sole purpose of verifying the accuracy and completeness of all financial, accounting and numerical information and calculations provided under this Agreement. The independent accounting firm shall have
the right to make copies of relevant portions of Payor’s books and records; provided however that any such copies shall be the Confidential Information of Payor, shall be protected by appropriate confidentiality obligations
and shall not be shared with Payee or any other Person. The sole deliverable to the Payee shall be a copy of the accounting firm’s final report, which also shall be provided to the Payor at the same time.

6.12.3 Such examination is to be made at the expense of Payee, except if the results of the audit reveal an underpayment of royalties or
sales milestone payments under this Agreement of [**] percent ([**]%) or more in any Calendar Year, in which case reasonable audit fees for such examination shall be paid by Payor. 

6.12.4 With respect to Net Sales invoiced in Dollars, the Net Sales and the amounts due hereunder will be expressed in Dollars. With
respect to Net Sales invoiced in a currency other than Dollars, the Net Sales and amounts due hereunder will be reported in Dollars, calculated using the standard methodologies employed by Payor for consolidation purposes. As of the Effective Date,
the method utilized by GSK’s group reporting system uses spot exchange rates sourced from Reuters/Bloomberg. 
 6.13
Taxes. 
 6.13.1 EPIZYME warrants that, as of the Effective Date, EPIZYME is resident for tax purposes in the United
States and that EPIZYME is entitled to relief from United Kingdom income tax under the terms of the double tax agreement between the United Kingdom and the United States (the “US/UK Treaty”). EPIZYME shall notify GSK immediately in writing
in the event that EPIZYME ceases to be entitled to such relief. GSK shall pay royalty income and any other payments under this Agreement to EPIZYME by deducting tax at the applicable rate specified in the US/UK Treaty; provided however
that, GSK acknowledges and agrees that as of the Effective Date such applicable tax rate under the US/UK Treaty is zero percent (0%); provided further that, this rate may increase if the US/UK Treaty is amended. EPIZYME
agrees to indemnify and hold harmless GSK against any loss, damage, expense or liability arising in any way from a breach of the above warranties or any future claim by a UK 

  
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tax authority or other similar body in the United Kingdom alleging that GSK was not entitled to deduct withholding tax on such payments at source at the rate specified in the US/UK Treaty.
Subject to the foregoing, any tax paid or required to be withheld by GSK for the benefit of EPIZYME on account of any royalties or other payments payable to EPIZYME under this Agreement shall be deducted from the amount of royalties or other
payments otherwise due and remitted to the proper taxing authority on behalf of EPIZYME. GSK shall secure and send to EPIZYME proof of any such taxes withheld and paid by GSK for the benefit of EPIZYME, and shall, at EPIZYME’s request, provide
reasonable assistance to EPIZYME in recovering such taxes or in claiming exemption from such deductions or withholdings under any applicable double taxation treaty or similar agreement. If GSK assigns its rights under this Agreement in accordance
with Section 13.4 and as a result of such assignment a greater amount of tax is required to be withheld from the payments to EPIZYME under this Agreement than would have been withheld in the absence of such assignment, then the assignee shall
be obligated to pay EPIZYME such additional amounts as may be necessary to ensure that EPIZYME receives the same net amount after such increased withholding as it would have received in the absence of such assignment. 

6.13.2 In the event royalties or any other payments are owed from EPIZYME to GSK on which United States withholding tax is required and a
reduced rate of withholding is available under the US/UK Treaty, GSK shall provide EPIZYME with a signed and completed U.S. Form W-8BEN, “Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding,” to secure the
reduced rate of withholding specified in the US/UK Treaty. GSK agrees to indemnify and hold harmless EPIZYME against any loss, damage, expense or liability arising in any way from any future claim by a US tax authority or other similar body in the
United States alleging that EPIZYME was not entitled to deduct withholding tax on such payments at source at the rate specified in the US/UK Treaty. Subject to the foregoing, any tax paid or required to be withheld by EPIZYME for the benefit of GSK
on account of any royalties or other payments payable to GSK under this Agreement shall be deducted from the amount of royalties or other payments otherwise due and remitted to the relevant taxing authority on behalf of GSK. EPIZYME shall secure and
send to GSK proof of any such taxes withheld and paid by EPIZYME for the benefit of GSK, and shall, at GSK’s request, provide reasonable assistance to GSK in recovering such taxes or in claiming exemption from such deductions or withholdings
under any applicable double taxation treaty or similar agreement. 
 6.14 Late Payments. Any undisputed amount owed by
Payor to Payee under this Agreement that is not paid on or before the date such payment is due shall bear interest at a rate per annum equal to the lesser of the prime or equivalent rate per annum quoted by The Wall Street Journal on the
first Business Day after such payment is due, plus [**] percent ([**]%), or the highest rate permitted by applicable Law, calculated on the number of days such payments are paid after such payments are due and compounded monthly. Interest shall not
accrue on undisputed amounts that were paid after the due date as a result of mistaken Payee actions (e.g., if a payment is late as a result of Payee providing an incorrect account for receipt of payment). In addition, the Payor shall
reimburse the Payee for all costs, including attorneys’ fees and legal expenses, incurred in the collection of late payments; provided however that the foregoing shall not apply to payments disputed in good faith by the
Payor unless the Payee is successful in such dispute or the Payor ceases to dispute such payments. 

  
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 ARTICLE 7 
 EXCLUSIVITY 
 7.1 Selected Target Exclusivity. 

7.1.1 During the Term. Except pursuant to this Agreement, on a Selected Target-by-Selected Target basis, during the Term, [**]
respective Affiliates shall, except as otherwise permitted in Section 7.1.2, either (a) alone or with or for any Third Party, [**] in the [**] any [**] to any Selected Target, or (b) grant a license or sublicense to, or otherwise
assist or contract with any Third Party, to [**] in the [**] any [**] to any Selected Target. 
 7.1.2 Exceptions.
Notwithstanding the foregoing: 
 (a) after [**] has been [**] for a Licensed Product directed to any Selected Target,
(i) [**] may [**] Compounds (excluding Licensed Compounds and Licensed Products, and related Diagnostic Products) directed to such Selected Target and not Covered by any EPIZYME IP, EPIZYME Diagnostic IP, Collaboration IP or Joint IP, and
(ii) [**] may [**] Compounds (excluding Licensed Compounds and Licensed Products, and related Diagnostic Products) directed to such Selected Target and not Covered by any GSK IP, Collaboration IP or Joint IP; 

(b) if a Change of Control Event occurs with respect to EPIZYME, and the Third Party that acquires, combines with or comes to control
EPIZYME as a result of such Change of Control Event (or any of such Third Party’s then-existing Affiliates) already has a program that existed prior to the Change of Control Event that would otherwise violate Section 7.1.1 above at the
time of such Change of Control Event, such Third Party (or Affiliate) shall be permitted to continue such program after such Change of Control Event and such continuation shall not constitute a violation of Section 7.1.1 above; provided
however that (i) none of the EPIZYME IP, EPIZYME Diagnostic IP, GSK IP, Collaboration IP Controlled by either Party, Joint IP, or other Patents or Know-How Controlled by GSK and licensed to EPIZYME hereunder (if any) shall be used
in such Third Party’s (or such Third Party’s Affiliate’s) program, and (ii) the research or Development activities required under this Agreement shall be conducted separately from any research or Development activities directed
to such Third Party’s (or such Third Party’s Affiliate’s) program, including the maintenance of separate lab notebooks and records (password-protected to the extent kept on a computer network) and separate personnel working on each of
the activities under this Agreement and the activities covered under such Third Party’s program. EPIZYME shall adopt reasonable procedures to limit the dissemination of Sensitive Information to only those personnel having a need to know such
Sensitive Information in order for EPIZYME and/or the Change of Control party, as applicable, to perform its obligations or to exercise its rights under this Agreement, including, in furtherance of the foregoing goal, adoption of reasonable
procedures to prohibit and limit the use and disclosure of Sensitive Information for competitive reasons against GSK and its Affiliates, including the use of Sensitive Information for the research, Development or Commercialization of Compounds, and
to prohibit or limit Sensitive Information from being disclosed to or used by any person who is also working on or making scientific, intellectual property or commercial decisions regarding Compounds at the time of receipt or use of any Sensitive
Information, or within [**] years 

  
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following receipt or use of any Sensitive Information. For the purpose of this Section 7.1.2(b), “Sensitive Information” means all Confidential Information of GSK with
respect to: the Research Plans; reports or data provided pursuant to Section 2.5; reports or timelines provided pursuant to Section 3.3; invoice details, royalty related reports or other commercially-sensitive GSK information; information
related to GSK prosecution efforts or the status of GSK enforcement efforts; information related to research, Development, manufacturing and Commercialization activities in connection with Licensed Compounds and Licensed Products directed to any
Selected Target, and all related Diagnostic Products, but excluding, for purposes of clarity, any information related to any Selected Target which becomes a Dropped Target, any Licensed Compound which becomes an EPIZYME Compound, any EPIZYME Product
comprising such EPIZYME Compound, or any related EPIZYME Diagnostic Product. The JSC, any Subcommittee(s) and the JPT, and their governance roles under the Agreement, as described in Sections 4.1, 4.2 and 4.3, shall be terminated; provided
however that the Alliance Manager and the Patent Liaisons, and their respective roles, as described in Sections 4.4 and 4.5 shall be retained; and 
 (c) for the avoidance of doubt, and except as otherwise provided in this Agreement, nothing in this Section 7.1 shall be construed or interpreted to limit [**] rights to conduct [**], on its own or
with or for a Third Party, directed to [**], or to [**] directed to [**]. 
 ARTICLE 8 

OWNERSHIP OF INTELLECTUAL PROPERTY RIGHTS 
 8.1 Ownership. 
 8.1.1 Pre-Existing Patents and Know-How; Intellectual
Property Arising Outside of This Agreement. EPIZYME shall retain all of its right, title and interest in, to and under the EPIZYME IP and EPIZYME Diagnostic IP existing prior to the Effective Date or arising outside of this Agreement, and GSK
shall retain all of its rights, title and interest in, to and under the GSK IP existing prior to the Effective Date or arising outside of this Agreement, except to the extent that any such rights are expressly licensed by one Party to the other
Party under this Agreement. 
 8.1.2 Intellectual Property Arising Under This Agreement. 

(a) GSK shall be the sole owner of any Patents and Know-How discovered, developed, invented, conceived or reduced to practice solely by
or on behalf of GSK under this Agreement (it being understood that any activities carried out by or on behalf of EPIZYME under this Agreement shall not be construed or interpreted to be carried out by or on behalf of GSK for purposes hereof), and
GSK shall retain all of its right, title and interest thereto, except to the extent that any rights or licenses are expressly granted thereunder by GSK to EPIZYME under this Agreement. 

(b) EPIZYME shall be the sole owner of any Patents or Know-How discovered, developed, invented, conceived or reduced to practice solely
by or on behalf of EPIZYME under this Agreement (it being understood that any activities carried out by or on 

  
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behalf of GSK under this Agreement shall not be construed or interpreted to be carried out by or on behalf of EPIZYME for purposes hereof), and EPIZYME shall retain all of its right, title and
interest thereto, except to the extent that any rights or licenses are expressly granted thereunder by EPIZYME to GSK under this Agreement. 
 (c) Any Joint Patents or Joint Know-How shall be owned jointly by GSK and EPIZYME, and all rights, title and interest thereto shall be jointly owned by the Parties, subject to any rights or licenses that
are expressly granted by one Party to the other Party under this Agreement. Except to the extent either Party is restricted by the licenses granted by one Party to the other Party pursuant to this Agreement, or the covenants contained herein, each
Party shall be entitled to practice and license the Joint Know-How and the Joint Patents without restriction and without consent of, or (subject to the financial provisions of this Agreement) an obligation to account to, the other Party, and each
Party hereby waives any right it may have under applicable Laws to require any such consent or accounting. 
 8.2 Prosecution
and Maintenance of Patents. The Parties will perform their respective activities under this Article 8.2 in accordance with the Patent Strategy to the extent reasonably practicable and legally permissible. 

8.2.1 EPIZYME Patents; EPIZYME Diagnostic Patents; Collaboration Patents Controlled by EPIZYME; Joint Patents. 

(a) Subject to Sections 8.2.3, 8.2.4 and 8.2.5, as between the Parties, EPIZYME shall have the first right (but not the obligation)
to Prosecute and Maintain the EPIZYME Patents, EPIZYME Diagnostic Patents, Collaboration Patents Controlled by EPIZYME, and Joint Patents. EPIZYME shall keep GSK informed as to material developments with respect to the Prosecution and Maintenance of
such Patents, including by providing copies of all substantive office actions or any other substantive documents that EPIZYME receives from any patent office, including notice of all interferences, reissues, re-examinations, oppositions or requests
for patent term extensions. 
 (b) EPIZYME shall also provide GSK with a reasonable opportunity to substantively comment on
Prosecution and Maintenance of EPIZYME Patents, EPIZYME Diagnostic Patents, Collaboration Patents Controlled by EPIZYME, and Joint Patents, in each case that Cover the Development, manufacture or Commercialization of any Licensed Compound, Licensed
Product or Diagnostic Product, prior to taking material actions (including the filing of initial applications), and will in good faith consider any actions recommended by GSK. GSK shall have the right to review and make comments on and
recommendations in relation to the Prosecution and Maintenance of such Patents; provided however that GSK does so promptly and consistent with any applicable filing deadlines. 

8.2.2 GSK Patents; Collaboration Patents Controlled by GSK. 

(a) Subject to Section 8.2.3, as between the Parties, GSK shall have the right (but not the obligation) to Prosecute and Maintain
the GSK Patents and Collaboration Patents Controlled by GSK. GSK shall keep EPIZYME informed as to material developments 

  
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with respect to the Prosecution and Maintenance of such Patents, including by providing copies of all substantive office actions or any other substantive documents that GSK receives from any
patent office, including notice of all interferences, reissues, re-examinations, oppositions or requests for patent term extensions. 
 (b) GSK shall also provide EPIZYME with a reasonable opportunity to substantively comment on the Prosecution and Maintenance of Collaboration Patents Controlled by GSK prior to taking material actions
(including the filing of initial applications), and will in good faith consider any actions recommended by EPIZYME. EPIZYME shall have the right to review and make comments on and recommendations in relation to the Prosecution and Maintenance of
such Collaboration Patents; provided however that EPIZYME does so promptly and consistent with any applicable filing deadlines. 
 8.2.3 Filing Decision or Prosecution Lapse. If, during the Term, the Party with the first right, pursuant to Sections 8.2.1, 8.2.2, 8.2.4 or 8.2.5, to Prosecute and Maintain an EPIZYME Patent,
EPIZYME Diagnostic Patent, Collaboration Patent or Joint Patent, as applicable, in any country decides not to file such Patent or intends to allow such Patent to lapse or become abandoned without having first filed a substitute, the prosecuting or
maintaining Party shall notify and consult with the other Party of such decision or intention at least [**] days prior to the date upon which the subject matter of such Patent shall become unpatentable or such Patent shall lapse or become abandoned,
and such other Party shall thereupon have the right (but not the obligation) to assume the Prosecution and Maintenance thereof at its own expense with counsel of its own choice. Notwithstanding the foregoing, GSK shall not have the right pursuant to
Section 8.2.1 to assume the Prosecution and Maintenance of any EPIZYME Patent, EPIZYME Diagnostic Patent, Collaboration Patent Controlled by EPIZYME or Joint Patent that is not related to any Selected Target, Licensed Compound, Licensed Product
or Diagnostic Product. 
 8.2.4 Cooperation Regarding the Filing and Prosecution of Divisional Patent Applications. The
Parties shall cooperate with one another, through their respective Patent Liaisons, to file and prosecute the EPIZYME Patents, EPIZYME Diagnostic Patents, Collaboration Patents and Joint Patents for which either Party is responsible for Prosecution
and Maintenance pursuant to this Section 8.2, including in the furtherance of the Patent Strategy. Notwithstanding Section 8.2.1, with respect to divisional Patent applications (or other Patent applications Controlled by EPIZYME) that are
primarily directed to Licensed Compound(s), Licensed Product(s) or Diagnostic Product(s) and not substantially directed to other compounds or products, as between the Parties GSK shall, subject to Section 8.2.3, have the right (but not the
obligation) to Prosecute and Maintain such Patents. GSK shall keep EPIZYME informed as to material developments with respect to the Prosecution and Maintenance of such Patents, including by providing copies of all substantive office actions or any
other substantive documents that GSK receives from any patent office, including notice of all interferences, reissues, re-examinations, oppositions or requests for patent term extensions. 

8.2.5 Notwithstanding Section 8.2.1, if, at such time as GSK reasonably determines that clinical proof-of-concept for such Licensed
Product has been demonstrated by data generated in one or more Phase 2 Clinical Trials, GSK does not already have the right to control the Prosecution and Maintenance of the EPIZYME Patent, Joint Patent or Collaboration

  
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Patent Controlled by EPIZYME that is reasonably likely to [**] the [**], then as between the Parties GSK shall, subject to Section 8.2.3, have the right (but not the obligation) to Prosecute
and Maintain such EPIZYME Patent, Joint Patent or Collaboration Patent Controlled by EPIZYME, as the case may be, that is reasonably likely to [**] the [**]. GSK shall keep EPIZYME informed as to material developments with respect to the Prosecution
and Maintenance of such Patent, including by providing copies of all substantive office actions or any other substantive documents that GSK receives from any patent office, including notice of all interferences, reissues, re-examinations,
oppositions or requests for patent term extensions. 
 8.3 Patent Costs. Each Party shall be responsible for all costs
and expenses associated with its Prosecution and Maintenance activities under Section 8.2. 
 8.4 Defense of Claims
Brought by Third Parties. If a Party becomes aware of any claim that the Development, manufacture or Commercialization of a Licensed Compound, Licensed Product or Diagnostic Product infringes the intellectual property rights of any Third Party,
such Party shall promptly notify the other Party. In any such instance, the Parties shall as soon as practicable thereafter discuss in good faith regarding the best response to such notice, subject to Article 11. 

8.5 Enforcement of EPIZYME Patents, EPIZYME Diagnostic Patents, Collaboration Patents and Joint Patents. 

8.5.1 Duty to Notify of Infringement. If any Party learns of an infringement or threatened infringement by a Third Party with
respect to any EPIZYME Patent, EPIZYME Diagnostic Patent, Collaboration Patent or Joint Patent, including actual or alleged infringement under 35 USC §271(e)(2) that is or would be competitive with a Licensed Compound, Licensed Product or
Diagnostic Product (“Competitive Infringement”), such Party shall promptly notify the other Party and shall provide such other Party with available evidence of such Competitive Infringement. 

8.5.2 Enforcement of EPIZYME Patents and EPIZYME Diagnostic Patents. Subject to Section 8.5.4, GSK shall have the primary
right, but not the obligation, to institute, prosecute, and control any action or proceeding with respect to any Competitive Infringement of EPIZYME Patents and EPIZYME Diagnostic Patents, by counsel of its own choice, and EPIZYME shall have the
right, at its own expense, to be represented in such action by counsel of its own choice. If GSK fails to bring an action or proceeding within a period of [**] days after first being notified of such Competitive Infringement (or [**] days after
being notified in the case of an action brought under the Hatch-Waxman Act or any ex-U.S. equivalent of the Hatch-Waxman Act), EPIZYME shall have the right to bring and control such an action by counsel of its own choice, and GSK shall have the
right to be represented in any such action by counsel of its own choice at its own expense. 
 8.5.3 Enforcement of
Collaboration Patents and Joint Patents that Cover Licensed Compounds. Subject to Section 8.5.4, GSK shall have the primary right, but not the obligation, to institute, prosecute, and control any action or proceeding with respect to any
Competitive Infringement of Collaboration Patents and Joint Patents, by counsel of its own 

  
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choice, and EPIZYME shall have the right, at its own expense, to be represented in such action by counsel of its own choice. If GSK fails to bring an action or proceeding within a period of [**]
days after first being notified of such Competitive Infringement (or [**] days after being notified in the case of an action brought under the Hatch-Waxman Act or any ex-U.S. equivalent of the Hatch-Waxman Act), EPIZYME shall have the right to bring
and control such an action by counsel of its own choice, and GSK shall have the right to be represented in any such action by counsel of its own choice at its own expense. 
 8.5.4 Enforcement of Collaboration Patents and Joint Patents that Cover EPIZYME Compounds. Notwithstanding anything in Section 8.5.2 or Section 8.5.3 to the contrary, EPIZYME shall have
the sole right, but not the obligation, to institute, prosecute, and control any action or proceeding with respect to infringements of EPIZYME Patents, EPIZYME Diagnostic Patents, Collaboration Patents and Joint Patents that are or would be
competitive with any EPIZYME Compound, EPIZYME Product or EPIZYME Diagnostic Product, by counsel of its own choice. 
 8.5.5
GSK Patents. For purposes of clarity, GSK shall have the sole right, at its own expense, to institute, prosecute, and control any action or proceeding with respect to any infringement of the GSK Patents, by counsel of its own choice.

 8.5.6 Settlement. A settlement or consent judgment or other voluntary final disposition of a suit under this
Section 8.5 may be entered into without the consent of the Party not bringing suit; provided however that any such settlement, consent judgment or other disposition of any action or proceeding by a Party under this Article
8 shall not, without the consent of the Party not bringing suit, (a) impose any liability or obligation on such Party, (b) include the grant of any license, covenant or other rights to any Third Party that would conflict with or reduce the
scope of the subject matter included under the exclusive licenses granted to such Party under this Agreement, or (c) conflict with or reduce the scope of the subject matter claimed in any Patent owned (solely or jointly) by the Party not
bringing suit. 
 8.5.7 Cooperation. If one Party brings any such action or proceeding in accordance with this
Section 8.5, the other Party agrees to be joined as a party plaintiff where legally required to initiate or maintain suit or collect damages, and to give the first Party reasonable assistance and authority to file and prosecute the suit.

 8.5.8 Costs and Recoveries. The costs and expenses of the Party bringing suit under this Section 8.5 shall be
borne by such Party, and any damages or other monetary awards recovered shall be shared as follows: 
 (a) the amount of such
recovery actually received by the Party controlling such action shall first be applied to the out-of-pocket costs incurred by each Party in connection with such action; and 
 (b) any remaining proceeds shall, in the case of suits with respect to Competitive Infringement relating to a Licensed Compound, Licensed Product or Diagnostic Product, be allocated between the Parties
such that the Party bringing suit under this Section 8.5 retains [**] and the other Party retains [**] of such amount. 

  
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 8.5.9 Regulatory Data Protection. To the extent required or permitted by applicable
Law, GSK will use Commercially Reasonable Efforts to promptly, accurately and completely list, with the applicable Regulatory Authorities during the Term, all applicable Patents for any Licensed Product that GSK intends to, or has begun to,
Commercialize and that have become the subject of an application for Regulatory Approval submitted to FDA, such listings to include all so called “Orange Book” listings required under the Hatch-Waxman Act and all so called “Patent
Register” listings as required in Canada. Prior to such listings, the Parties will meet to evaluate and identify all applicable Patents. Notwithstanding the preceding sentence, GSK will retain final decision-making authority as to the listing
of all applicable Patents for such Licensed Product, regardless of which Party owns such Patent. 
 8.5.10 Patent Term
Extensions. EPIZYME and GSK shall discuss and seek to reach mutual agreement for which, if any, of the Patents within the EPIZYME Patents, EPIZYME Diagnostic Patents, Collaboration Patents, Joint Patents or GSK Patents the Parties shall apply to
obtain patent term extensions, adjustments, restorations, or supplementary protection certificates under applicable Laws, based on the [**] of the Licensed Products or Diagnostic Products Covered by such Patents. If the Parties are unable to reach
mutual agreement, GSK shall have the right to make the final decision. 
 ARTICLE 9 

CONFIDENTIALITY 
 9.1 Confidentiality; Exceptions. Except to the extent expressly authorized by this Agreement or otherwise agreed in writing, the Parties agree that the receiving Party (the “Receiving
Party”) shall keep confidential and shall not publish or otherwise disclose or use for any purpose other than as provided for in this Agreement any Know-How or other confidential and proprietary information and materials, patentable or
otherwise, in any form (written, oral, photographic, electronic, magnetic, or otherwise) which is disclosed to it by the other Party (the “Disclosing Party”) or otherwise received or accessed by a Receiving Party in the course of
performing its obligations or exercising its rights under this Agreement, including trade secrets, Know-How, inventions or discoveries, proprietary information, formulae, processes, techniques and information relating to a Party’s past, present
and future marketing, financial and research or Development activities of any product or potential product or useful technology of the Disclosing Party and the pricing thereof (collectively, “Confidential Information”), except to
the extent that it can be established by the Receiving Party that such Confidential Information: 
 (a) was in the lawful
knowledge and possession of the Receiving Party prior to the time it was disclosed to, or learned by, the Receiving Party, or was otherwise developed independently by the Receiving Party, as evidenced by written records kept in the ordinary course
of business, or other documentary proof of actual use by the Receiving Party; 
 (b) was generally available to the public or
otherwise part of the public domain at the time of its disclosure to the Receiving Party; 

  
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 (c) became generally available to the public or otherwise part of the public domain after
its disclosure and other than through any act or omission of the Receiving Party in breach of this Agreement; or 
 (d) was
disclosed to the Receiving Party, other than under an obligation of confidentiality, by a Third Party who had no obligation to the Disclosing Party not to disclose such information to others. 

9.2 Authorized Disclosure. Except as expressly provided otherwise in this Agreement, a Receiving Party may use and disclose
Confidential Information of the Disclosing Party as follows: 
 (a) under appropriate confidentiality provisions similar to
those in this Agreement, in connection with the performance of its obligations or exercise of rights granted or reserved in this Agreement (including the rights to research, Develop and Commercialize Licensed Products or EPIZYME Products, as
applicable, and to grant licenses and sublicenses hereunder); 
 (b) to the extent such disclosure is reasonably necessary in
filing or prosecuting patent, copyright and trademark applications, prosecuting or defending litigation, complying with applicable governmental regulations, seeking and obtaining Regulatory Approval, conducting non-clinical activities or Clinical
Trials, preparing and submitting INDs to Regulatory Authorities, marketing Licensed Products or EPIZYME Products, as applicable, or is otherwise required by applicable Law; provided however that if a Receiving Party is required
by applicable Law to make any such disclosure of a Disclosing Party’s Confidential Information it will, except where impracticable, give reasonable advance notice to the Disclosing Party of such disclosure requirement and, if requested by the
Disclosing Party, reasonably cooperate with the Disclosing Party to secure confidential treatment of such Confidential Information required to be disclosed; 
 (c) in communication with actual or potential investors, lenders, acquirors, merger partners, consultants, advisors, licensees, sublicensees, collaborators or others on a need to know basis, in each case
under appropriate confidentiality provisions substantially equivalent to those of this Agreement; or 
 (d) to the extent
mutually agreed in writing by the Parties. 
 9.3 Press Release; Disclosure of Agreement. 

9.3.1 Press Release. On or after the Effective Date, EPIZYME shall have the right to issue a public announcement of the execution
of this Agreement, in the form agreed by the Parties as of the Effective Date. Thereafter, except as otherwise set forth in Section 9.3.2 or Section 9.3.3, EPIZYME shall not be free to issue any subsequent press release or other public
disclosure regarding this Agreement or the Parties’ activities hereunder, or any results or data arising hereunder, except (a) with GSK’s prior written consent, which shall not be unreasonably withheld, or (b) for any disclosure
that is reasonably necessary to comply with applicable securities exchange listing requirements or other applicable Laws; provided however that with 

  
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respect to (b) the announcing party shall determine, in consultation with legal counsel, whether such disclosure is required under such securities exchange listing requirements or other
applicable Laws, and if so required, shall take reasonable steps to minimize such disclosure while remaining in compliance with such requirements or applicable Laws. 
 9.3.2 Exceptions. EPIZYME shall have the right to issue press releases or other public disclosures with respect to the following matters, (i) with GSK’s prior consent as provided in
Section 9.3.1, or (ii) without obtaining consent from GSK if such information has become public other than through a breach by EPIZYME of the confidentiality provisions of this Article 9: 

(a) completion of clinical trials and top line results thereof; 

(b) submissions of INDs to Regulatory Authorities in the U.S., the EU, any country in the EU and Japan; 

(c) the date and circumstances under which an IND becomes effective in the U.S., the EU, any country in the EU and Japan; 

(d) completion of patient enrollments for clinical trials; 
 (e) filings for Regulatory Approval in the U.S., the EU, any country in the EU and Japan; 
 (f) Regulatory Approvals in the U.S., the EU, any country in the EU and Japan; and 
 (g) reimbursement decisions by governmental authorities in the U.S., the EU, any country in the EU and Japan. 
 In addition, EPIZYME shall have the right to issue press releases or other public disclosures with respect to the following matters without having to obtain the prior written consent of GSK: 

 

	 	(x)	any EPIZYME equity financing in which GSK participates in accordance with Section 6.3; 

 

	 	(y)	milestone achievements or payments relating to any milestone specified in this Agreement; and 

 

	 	(z)	information related to Dropped Targets, EPIZYME Compounds, EPIZYME Products and EPIZYME Diagnostic Products. 

9.3.3 Disclosure of Agreement Terms. 
 (a) Except to the extent required by applicable Law or as otherwise permitted in accordance with this Section 9.3, including as permitted under Section 9.3.2, EPIZYME shall not make any public
announcements concerning this Agreement or the subject 

  
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matter hereof without the prior written consent of GSK, which shall not be unreasonably withheld, conditioned or delayed. Each Party agrees to provide to the other Party a copy of any public
announcement regarding this Agreement or the subject matter hereof, as practicable under the circumstances, reasonably prior to its scheduled release, but in no event less than [**] Business Days. GSK shall have the right to expeditiously review and
recommend changes to any such announcement by EPIZYME, and, except as otherwise required by securities exchange listing requirements or applicable Law, EPIZYME shall remove any Confidential Information of GSK that GSK reasonably deems to be
inappropriate for disclosure. 
 (b) Notwithstanding the foregoing, to the extent information regarding this Agreement has
already been publicly disclosed, either Party may subsequently disclose the same information to the public without the consent of the other Party; provided however that such subsequent disclosure does not materially alter the
original meaning of the information disclosed. Each Party shall also be permitted to disclose the terms of this Agreement, in each case under appropriate confidentiality provisions substantially equivalent to those of this Agreement, to any bona
fide actual or potential acquirors, merger partners, licensees, sublicensees, collaborators, investors, lenders and professional advisors. 
 (c) Each Party shall give the other Party a reasonable opportunity to review those portions of all filings with the United States Securities and Exchange Commission (or any stock exchange, including
Nasdaq, or any similar regulatory agency in any country other than the U.S.) describing the terms of this Agreement (including any filings of this Agreement) prior to submission of such filings, and shall give due consideration to any reasonable
comments by the non-filing Party relating to such filing, including the provisions of this Agreement for which confidential treatment should be sought. 
 9.4 Prior Disclosures of Confidential Information. Any and all Know-How or other confidential and proprietary information and materials, patentable or otherwise, in any form, which may have been
exchanged between the Parties prior to the Effective Date, under the Confidential Disclosure Agreement between EPIZYME and GSK dated February 24, 2009 (the “Existing Confidentiality Agreement”), shall be deemed Confidential
Information hereunder and shall be subject to the terms of this Article 9. This Agreement supersedes and replaces the Existing Confidentiality Agreement. 
 9.5 Remedies. Each Party shall be entitled to seek, in addition to any other right or remedy it may have, at Law or in equity, a temporary injunction, without the posting of any bond or other
security, enjoining or restraining the other Party from any violation or threatened violation of this Article 9. 
 9.6
Publications. 
 9.6.1 Restrictions on Publication. Neither Party nor its Affiliates shall publish or publicly
disclose the results generated during the course of performing the Research Plans, or in the Development or Commercialization activities directed to any Selected Target conducted by either Party under this Agreement without the prior written consent
of the other Party, except as otherwise expressly permitted in this Section 9.6, in Section 9.7 or otherwise in this 

  
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Agreement, including in Section 9.3.2. Both Parties (and their respective Affiliates and Sublicensees) shall be permitted to publish or publicly disclose results of activities conducted
under the Research Plans under the Collaboration, subject to the prior review by the other Party for patentability and protection of its Confidential Information as described in this Section 9.6. In addition, GSK (and its Affiliates and
Sublicensees) shall be permitted to publish or publicly disclose results generated in the course of conducting the Research Plans, or in the Development and Commercialization activities hereunder relating to Licensed Compounds and Licensed Products
that are directed to Selected Targets, subject to the prior review by EPIZYME for patentability and protection of its Confidential Information as described in this Section 9.6. Notwithstanding the foregoing, as between EPIZYME and GSK, only
EPIZYME shall have the right to publish or publicly disclose results of Collaboration activities (but not Confidential Information of GSK generated outside of the Collaboration) related to any Dropped Target, EPIZYME Compound or EPIZYME Product, and
EPIZYME shall have the right to do so (a) in the case of Dropped Targets, EPIZYME Compounds or EPIZYME Products as to which EPIZYME is in possession of Confidential Information of GSK that GSK generated outside the Collaboration, subject to the
submission and review procedure set forth in this Section 9.6 and (b) otherwise, without being subject to the submission and review procedure set forth in this Section 9.6. 

9.6.2 Submission; Review. The Party seeking to publish results hereunder (the “Publishing Party”) shall provide
the other Party (the “Reviewing Party”) with a copy of such proposed abstract, manuscript, or presentation no less than [**] days ([**] days in the case of abstracts) prior to its intended submission for publication. The reviewing
Party shall respond in writing promptly and in no event later than [**] days ([**] Business Days in the case of abstracts) after receipt of the proposed material, with one or more of the following: 

(a) comments on the proposed material, which the publishing Party shall consider in good faith; 

(b) a specific statement of concern, based upon the need to seek patent protection or to block publication if the reviewing Party
determines that the proposed disclosure is intellectual property that should be maintained as a trade secret to protect a Compound or any research or Development activities conducted under this Agreement; or 

(c) an identification of the reviewing Party’s Confidential Information that is contained in the material reviewed. 

9.6.3 Patent and Trade Secret Protection. In the event of concern over patent protection or whether maintaining a trade secret
would be a priority, the publishing Party agrees not to submit such publication or to make such presentation that contains such information until the reviewing Party is given a reasonable period of time, and in no event less than [**] days, to seek
patent protection for any material in such publication or presentation which it believes is patentable or to resolve any other issues or to abandon such proposed publication or presentation if the reviewing Party reasonably determines in good faith
that maintaining such information as a trade secret is a commercially-reasonable priority. Any Confidential Information of the reviewing Party shall, if requested by the reviewing Party, be removed. 

  
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 9.6.4 Review of Third Party Materials. With respect to any proposed abstracts,
manuscripts or summaries of presentations by investigators or other Third Parties conducting activities under the Research Plans or Development with or on behalf of a Party hereunder and who have a right to seek to publish results or information
hereunder to the same extent that GSK or EPIZYME (as the case may be) has the right to do so, such materials shall be subject to review by the other Party under this Section 9.6 to the same extent that GSK or EPIZYME (as the case may be) has
the right to do so. 
 9.7 Clinical Trial Register. Notwithstanding Sections 9.1 and 9.6, each of GSK and EPIZYME shall
have the right to publish summaries of data and results from any human clinical trials conducted by such Party under this Agreement on its clinical trials registry or on a government-sponsored database such as www.clinicaltrials.gov or other
publicly available websites such as www.clinicalstudyresults.org, without requiring the consent of the other Party. The Parties shall reasonably cooperate if needed in order to ensure the publication of any such summaries of human clinical trials
data and results as required on the clinical trial registry of each Party and any government-sponsored database such as clinicaltrials.gov or other publicly available websites such as www.clinicalstudyresults.org. 

ARTICLE 10 

REPRESENTATIONS AND WARRANTIES 
 10.1 Representations and Warranties of Both Parties. Each Party hereby represents and warrants to the other Party, as of the Effective Date, that: 

(a) Such Party is duly organized, validly existing and in good standing under the Laws of the jurisdiction of its incorporation and has
full corporate power and authority to enter into this Agreement and to carry out the provisions hereof; 
 (b) Such Party has
taken all necessary action on its part to authorize the execution and delivery of this Agreement and the performance of its obligations hereunder; 
 (c) This Agreement has been duly executed and delivered on behalf of such Party, and constitutes a legal, valid, binding obligation, enforceable against it in accordance with the terms hereof; 

(d) The execution, delivery and performance of this Agreement by such Party does not conflict with any agreement or any provision
thereof, or any instrument or understanding, oral or written, to which it is a party or by which it is bound, nor violate any applicable Law or regulation of any court, governmental body or administrative or other agency having jurisdiction over
such Party; 
 (e) No government authorization, consent, approval, license, exemption of or filing or registration with any
court or governmental department, commission, board, bureau, agency or instrumentality, domestic or foreign, under any applicable Laws currently in effect, is or will be necessary for, or in connection with, the transaction contemplated by this
Agreement or any other agreement or instrument executed in connection herewith, or for the performance by it of its obligations under this Agreement and such other agreements except as may be required to conduct Clinical Trials or to seek or obtain
Regulatory Approvals; and 
 (f) To its knowledge, it has not (i) employed and has not used a contractor or consultant
that has employed, any individual or entity debarred by the FDA (or subject to a similar sanction of EMA), or, (ii) employed any individual who or entity that is the subject of an FDA debarment investigation or proceeding (or similar proceeding
of EMA), in the conduct of any pre-clinical activities or clinical studies of Compounds. 

  
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 10.2 Representations and Warranties of EPIZYME. EPIZYME hereby represents and
warrants to GSK, as of the Effective Date, that (except as EPIZYME has disclosed to GSK as of the Effective Date): 
 (a)
EPIZYME has the right to grant all rights and licenses it purports to grant to GSK with respect to the EPIZYME IP and EPIZYME Diagnostic IP under this Agreement; 
 (b) EPIZYME has not granted as of the Effective Date any right or license to any Third Party relating to any of the EPIZYME IP or EPIZYME Diagnostic IP that would conflict or interfere with or limit the
scope of any of the rights or licenses granted to GSK hereunder; 
 (c) EPIZYME has not granted any liens or security interests
on the EPIZYME IP or EPIZYME Diagnostic IP; 
 (d) Neither EPIZYME nor its Affiliates has received any written notice of any
claim that any Patent or trade secret right owned or controlled by a Third Party would be infringed or misappropriated by the manufacture, use, sale, offer for sale or importation of Licensed Compounds, Licensed Products or Diagnostic Products by
GSK, its Affiliates or Sublicensees as contemplated by this Agreement; 
 (e) To its knowledge, the EPIZYME IP and the EPIZYME
Diagnostic IP are not being infringed or misappropriated by any Third Party. 
 10.3 Mutual Covenants. Each Party hereby
covenants to the other Party that: 
 (a) All employees of such Party or its Affiliates working under this Agreement will be
under the obligation to assign all right, title and interest in and to their inventions and discoveries, whether or not patentable, to such Party as the sole owner thereof; 
 (b) To the best of its knowledge without further duty of inquiry such Party will not (i) employ or use any contractor or consultant that employs, any individual or entity debarred by the FDA (or
subject to a similar sanction of EMA) or, (ii) employ any individual who or entity that is the subject of an FDA debarment investigation or proceeding (or similar proceeding of EMA), in each of subclauses (i) and (ii) in the conduct
of its activities under this Agreement; and 
 (c) Neither Party shall, during the Term, grant any right or license to any
Third Party relating to any of the intellectual property rights it owns or Controls which would conflict with any of the rights or licenses granted to the other Party hereunder. 

  
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 10.4 Disclaimer. EXCEPT AS OTHERWISE EXPRESSLY SET FORTH IN THIS AGREEMENT, NEITHER
PARTY MAKES ANY REPRESENTATION OR EXTENDS ANY WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY WARRANTY THAT ANY PATENTS ARE VALID OR ENFORCEABLE, AND EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. Without limiting the generality of the foregoing, each Party disclaims any warranties with regards to: (a) the success of any study or test commenced under this Agreement, (b) the safety or
usefulness for any purpose of the technology or materials, including any Compounds, it provides or discovers under this Agreement; or (c) the validity, enforceability, or non-infringement of any intellectual property rights or technology it
provides or licenses to the other Party under this Agreement. 
 ARTICLE 11 

INDEMNIFICATION; INSURANCE 
 11.1 Indemnification by GSK. GSK shall indemnify, defend and hold harmless EPIZYME and its Affiliates, and its or their respective directors, officers, employees and agents, from and against any
and all liabilities, damages, losses, costs and expenses, including the reasonable fees of attorneys and other professional Third Parties (collectively, “Losses”), arising out of or resulting from any and all Third Party suits,
claims, actions, proceedings or demands (“Claims”) based upon: 
 (a) the gross negligence or willful
misconduct of GSK or its Affiliates and its or their respective directors, officers, employees and agents, in connection with GSK’s performance of its obligations or exercise of its rights under this Agreement; 

(b) any breach of any representation or warranty or express covenant made by GSK under Article 10 or any other provision under this
Agreement; or 
 (c) the research that is actually conducted by or on behalf of GSK (excluding any research carried out by or
on behalf of EPIZYME hereunder in accordance with the Research Plans), the handling and storage by or on behalf of GSK of any chemical agents or other compounds for the purpose of conducting research by or on behalf of GSK, and the Development,
manufacture, marketing, Commercialization and sale by GSK, its Affiliates or Sublicensees of any Licensed Compound, Licensed Product or Diagnostic Product, including (i) any product liability, personal injury, property damage or other damage,
and (ii) infringement of any Patent or other intellectual property rights of any Third Party, in each case resulting from any of the foregoing activities described in this Section 11.1(c); 

in each case, provided however that, such indemnity shall not apply to the extent EPIZYME has an indemnification obligation pursuant
to Section 11.2 for such Loss. 

  
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 Any Losses as to which GSK is required to indemnify EPIZYME pursuant to the foregoing clause (c)(ii) shall
be deemed to be royalties paid by GSK to Third Parties with respect to license rights to Third Party Patents or Know-How necessary for the manufacture, use, offer for sale, sale or importation of the applicable Licensed Product in the applicable
country, and for which the provisions of Section 6.8.4 shall apply. 
 11.2 Indemnification by EPIZYME. EPIZYME
shall indemnify, defend and hold harmless GSK and its Affiliates, and its or their respective directors, officers, employees and agents, from and against any and all Losses, arising out of or resulting from any and all Third Party Claims based upon:

 (a) the gross negligence or willful misconduct of EPIZYME or its Affiliates or its or their respective directors, officers,
employees and agents, in connection with EPIZYME’s performance of its obligations or exercise of its rights under this Agreement; 
 (b) any breach of any representation or warranty or express covenant made by EPIZYME under Article 10 or any other provision under this Agreement; or 

(c) the research actually conducted by or on behalf of EPIZYME (excluding any research carried out by or on behalf of GSK or its
Affiliate or Sublicensee; provided however that the research which is to be carried out by or on behalf of EPIZYME under the Research Plans hereunder shall not be considered or interpreted to be research carried out by or on
behalf of GSK or its Affiliate or Sublicensee), the handling and storage by or on behalf of EPIZYME of any chemical agents or other compounds for the purpose of conducting research by or on behalf of EPIZYME, and the Development, manufacture,
marketing, Commercialization and sale by EPIZYME, its Affiliate or Sublicensee of any EPIZYME Compound, EPIZYME Product or EPIZYME Diagnostic Product, including (i) any product liability, personal injury, property damage or other damage, and
(ii) infringement of any Patent or other intellectual property rights of any Third Party, in each case resulting from any of the foregoing activities described in this Section 11.2(c); 

in each case, provided however that, such indemnity shall not apply to the extent GSK has an indemnification obligation pursuant to
Section 11.1 for such Loss. 
 Any Losses as to which EPIZYME is required to indemnify GSK pursuant to the foregoing clause (c)(ii) shall
be deemed to be royalties paid by EPIZYME to Third Parties with respect to license rights to Third Party Patents or Know-How necessary for the manufacture, use, offer for sale, sale or importation of the applicable EPIZYME Licensed Product in the
applicable country, and for which the provisions of Section 6.9.2 shall apply. 
 11.3 Procedure. 

11.3.1 Notice of Claim. A Person entitled to indemnification under this Article 11 (an “Indemnified Party”) shall
give prompt written notification to the Person from whom indemnification is sought (the “Indemnifying Party”) of the commencement of any action, suit or proceeding relating to a Third Party claim for which indemnification may be
sought or, if earlier, upon the assertion of any such claim by a Third Party (it being understood and agreed, however, 

  
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that the failure by an Indemnified Party to give notice of a Third-Party claim as provided in this Section 11.3 shall not relieve the Indemnifying Party of its indemnification obligation
under this Agreement except and only to the extent that such Indemnifying Party is actually damaged as a result of such failure to give notice). 
 11.3.2 Assumption of Defense; Participation. Within [**] days after delivery of such notification, the Indemnifying Party may, upon written notice thereof to the Indemnified Party, assume control
of the defense of such action, suit, proceeding or claim with counsel reasonably satisfactory to the Indemnified Party. If the Indemnifying Party does not assume control of such defense, the Indemnified Party shall control such defense and, without
limiting the Indemnifying Party’s indemnification obligations, the Indemnifying Party shall reimburse the Indemnified Party for all costs and expenses, including reasonable attorneys’ fees, incurred by the Indemnified Party in defending
itself within [**] days after receipt of any invoice therefor from the Indemnified Party. The Party not controlling such defense may participate therein at its own expense; provided however that, if the Indemnifying Party
assumes control of such defense and the Indemnified Party in good faith concludes, based on advice from counsel, that the Indemnifying Party and the Indemnified Party have conflicting interests with respect to such action, suit, proceeding or claim,
the Indemnifying Party shall be responsible for the reasonable fees and expenses of counsel to the Indemnified Party in connection therewith. The Party controlling such defense shall keep the other Party advised of the status of such action, suit,
proceeding or claim and the defense thereof and shall consider recommendations made by the other Party with respect thereto. 

11.3.3 Settlements. The Indemnified Party shall not agree to any settlement of such action, suit, proceeding or claim without the
prior written consent of the Indemnifying Party, which shall not be unreasonably withheld, delayed or conditioned. The Indemnifying Party shall not agree to any settlement of such action, suit, proceeding or claim or consent to any judgment in
respect thereof that does not include a complete and unconditional release of the Indemnified Party from all liability with respect thereto, that imposes any liability or obligation on the Indemnified Party or that acknowledges fault by the
Indemnified Party without the prior written consent of the Indemnified Party. 
 11.4 Insurance. 

11.4.1 EPIZYME’s Insurance Obligations. EPIZYME shall maintain, at its cost, insurance against liability and other risks
associated with its activities and obligations under this Agreement, including its Clinical Trials, the Commercialization of EPIZYME Products and its indemnification obligations hereunder, in such amounts, subject to such deductibles and on such
terms as are customary for a company such as EPIZYME for the activities to be conducted by it under this Agreement. EPIZYME shall furnish to GSK evidence of such insurance upon request. 

11.4.2 GSK’s Insurance Obligations. GSK hereby represents and warrants to EPIZYME that it is self-insured against liability
and other risks associated with its activities and obligations under this Agreement, including its Clinical Trials, the Commercialization of Licensed Products and its indemnification obligations hereunder, in such amounts and on such terms as are
customary for large pharmaceutical companies in the pharmaceutical industry for the activities to be conducted by it under this Agreement. GSK shall furnish to EPIZYME evidence of such self-insurance upon request. 

  
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 11.5 LIMITATION OF LIABILITY. EXCEPT FOR A BREACH OF ARTICLE 7 OR ARTICLE 9 OR FOR
CLAIMS OF A THIRD PARTY THAT ARE SUBJECT TO INDEMNIFICATION UNDER THIS ARTICLE 11, NEITHER EPIZYME NOR GSK, NOR ANY OF THEIR RESPECTIVE AFFILIATES OR SUBLICENSEES, WILL BE LIABLE TO THE OTHER PARTY TO THIS AGREEMENT, ITS AFFILIATES OR ANY OF THEIR
SUBLICENSEES FOR ANY INDIRECT, INCIDENTAL, CONSEQUENTIAL, SPECIAL OR PUNITIVE DAMAGES OR LOST PROFITS OR ROYALTIES, LOST DATA OR COST OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, WHETHER LIABILITY IS ASSERTED IN CONTRACT, TORT (INCLUDING
NEGLIGENCE AND STRICT PRODUCT LIABILITY), INDEMNITY OR CONTRIBUTION, AND IRRESPECTIVE OF WHETHER THAT PARTY OR ANY REPRESENTATIVE OF THAT PARTY HAS BEEN ADVISED OF, OR OTHERWISE MIGHT HAVE ANTICIPATED THE POSSIBILITY OF, ANY SUCH LOSS OR DAMAGE.

 ARTICLE 12 
 TERM AND TERMINATION 
 12.1 Term; Expiration. 

12.1.1 Term. This Agreement shall become effective on the Effective Date and, unless earlier terminated pursuant to this Article
12, shall remain in effect until it expires (the “Term”) as follows: 
 (a) On a Licensed Product-by-Licensed
Product or EPIZYME Product-by-EPIZYME Product (as applicable) and country-by-country basis, this Agreement shall expire on the date of the expiration of all applicable Royalty Terms with respect to such Licensed Product or EPIZYME Product in such
country; and 
 (b) This Agreement shall expire in its entirety upon the expiration of all applicable Royalty Terms under this
Agreement with respect to all Licensed Products or EPIZYME Products (as applicable) in all countries in the Territory. 
 12.1.2
Effect of Expiration. After the expiration of the Term pursuant to Section 12.1.1 above, the following terms shall apply: 
 (a) After expiration of the Term (but not after early termination) with respect to any Licensed Product in a country pursuant to Section 12.1.1(a), GSK shall have an exclusive, fully-paid,
royalty-free right and license, with the right to grant sublicenses, under the EPIZYME IP, EPIZYME Diagnostic IP, Collaboration IP Controlled by EPIZYME and EPIZYME’s interest in the Joint IP, in each case used at the time of such expiration,
to continue to make, have made, use, sell, offer to sell and import such Licensed Product (and any related Diagnostic Product) in the Field in such country, for so long as it continues to do so. 

  
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 (b) After expiration of the Term (but not after early termination) with respect to any
EPIZYME Product in a country pursuant to Section 12.1.1(a), EPIZYME shall have an exclusive, fully-paid, royalty-free right and license, with the right to grant sublicenses, under GSK IP, Collaboration IP Controlled by GSK, and GSK’s
interest in the Joint IP, in each case to the extent used at the time of such expiration, to continue to make, have made, use, offer to sell, sell and import such EPIZYME Product (and any related EPIZYME Diagnostic Product) in the Field in such
country, for so long as it continues to do so. 
 (c) After expiration of the Term (but not after early termination) with
respect to this Agreement in its entirety pursuant to Section 12.1.1(b), GSK shall have an exclusive, fully-paid, royalty-free right and license, with the right to grant sublicenses, under the EPIZYME IP, EPIZYME Diagnostic IP, Collaboration IP
Controlled by EPIZYME and EPIZYME’s interest in the Joint IP, in each case used at the time of such expiration, to continue to make, have made, use, offer to sell, sell and import Licensed Products (and any related Diagnostic Products) in the
Field in the Territory, for so long as it continues to do so. 
 (d) After expiration of the Term (but not after early
termination) with respect to this Agreement in its entirety pursuant to Section 12.1.1(b), EPIZYME shall have an exclusive, fully-paid, royalty-free right and license, with the right to grant sublicenses, under GSK IP, Collaboration IP
Controlled by GSK, and GSK’s interest in the Joint IP, in each case used at the time of such expiration, to continue to make, have made, use, offer to sell, sell and import EPIZYME Products (and any related EPIZYME Diagnostic Products) in the
Field in the Territory, for so long as it continues to do so. 
 12.2 Unilateral Termination by GSK. GSK shall have the
right, at its sole discretion, exercisable at any time to terminate this Agreement with respect to one or more Selected Targets upon ninety (90) days prior written notice to EPIZYME hereunder. In addition, GSK shall have the right, at its sole
discretion, exercisable at any time to terminate this Agreement in its entirety upon ninety (90) days prior written notice to EPIZYME hereunder. 
 12.3 Termination for Cause. 
 12.3.1 Termination for Material
Breach. 
 (a) Either Party (the “Non-Breaching Party”) may, without prejudice to any other remedies
available to it under applicable Law or in equity, terminate this Agreement on a Selected Target-by-Selected Target basis if the other Party (the “Breaching Party”) shall have materially breached or defaulted in the performance of
its obligations hereunder with respect to such Selected Target (or Licensed Compounds or Licensed Products directed to such Selected Target, or any related Diagnostic Product), and such default shall have continued for [**] days (or, in the case of
a payment breach, [**] Business Days) after written notice thereof was provided to the Breaching Party by the Non-Breaching Party, such notice describing the alleged breach. Subject to Section 12.3.2, any such termination of this Agreement
under this Section 12.3.1 shall become effective at the end of such [**] day (or [**] Business Day, as applicable) cure period, unless: 
 (i) the Breaching Party has cured such breach or default prior to the expiration of such cure period; or 

  
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 (ii) such breach is not susceptible to cure within such cure period even with the use of
Commercially Reasonable Efforts, in which event the Non-Breaching Party’s right to termination shall be suspended only if and for so long as (A) the Breaching Party has provided to the Non-Breaching Party a written plan that is reasonably
calculated to effect a cure, (B) such plan is reasonably acceptable to the Non-Breaching Party, and (C) the Breaching Party commits to and does carry out such plan; provided however that, unless otherwise mutually
agreed by the Parties in such plan, in no event shall such suspension of the Non-Breaching Party’s right to terminate extend beyond [**] days after the original cure period. 

(b) The right of either Party to terminate this Agreement, or a portion of this Agreement, as provided in this Section 12.3.1 shall
not be affected in any way by such Party’s waiver or failure to take action with respect to any previous default. 
 12.3.2
Disagreement. If the Parties reasonably and in good faith disagree as to whether there has been a material breach, the Party that seeks to dispute that there has been a material breach may contest the allegation in accordance with
Section 13.1. The cure period for any allegation made in good faith as to a material breach under this Agreement will, subject to Sections 12.3.1 and 13.2, run from the date that written notice was first received by the Breaching Party from the
Non-Breaching Party. 
 12.4 Termination for Patent Challenges. 

12.4.1 If GSK or any of its Affiliates or Sublicensees: 
 (a) commences or otherwise voluntarily determines to participate in (other than as may be necessary or reasonably required to assert a cross-claim or a counter-claim or to respond to a court request or
order or administrative law request or order) any action or proceeding (including any patent opposition or re-examination proceeding), challenging or denying the validity of any EPIZYME Patent, EPIZYME Diagnostic Patent, Collaboration Patent
Controlled by EPIZYME, or Joint Patent, in each case that is exclusively licensed to GSK hereunder, or any claim of any of the foregoing; or 
 (b) actively assists any other Person (other than as may be necessary or reasonably required to assert a cross-claim or a counter-claim or to respond to a court request or order or administrative law
request or order) in bringing or prosecuting any action or proceeding (including any patent opposition or re-examination proceeding) challenging or denying the validity of any of such Patents, in each case that are licensed exclusively to GSK
hereunder, or any claim thereof (each activity under the foregoing clause (a) or (b), a “GSK Patent Challenge”); 
 then
EPIZYME shall have the right to terminate this Agreement with respect to the Selected Target(s) to which the GSK Patent Challenge relates (and all Licensed Compounds and Licensed Products directed to such Selected Target(s), and all related
Diagnostic Products), upon thirty (30) days’ written notice to GSK; provided however that, EPIZYME’s right to terminate this 

  
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Agreement under this Section 12.4 shall not apply to any Affiliate of GSK that first becomes an Affiliate of GSK after the Effective Date of this Agreement in connection with a merger or
acquisition event, where such Affiliate of GSK was undertaking activities in connection with a GSK Patent Challenge prior to such merger or acquisition event; provided however that GSK causes such GSK Patent Challenge to
terminate within [**] days after such merger or acquisition event. For the avoidance of doubt, an action by GSK in accordance with Article 8 to amend claims within a pending patent application of EPIZYME during the course of GSK’s Prosecution
of such pending patent application or in defense of a Third Party opposition shall not constitute a challenge under this Section 12.4. 
 12.4.2 If EPIZYME or any of its Affiliates or Sublicensees: 
 (a) commences or
otherwise voluntarily determines to participate in (other than as may be necessary or reasonably required to assert a cross-claim or a counter-claim or to respond to a court request or order or administrative law request or order) any action or
proceeding (including any patent opposition or re-examination proceeding), challenging or denying the validity of any GSK Patent, Collaboration Patent Controlled by GSK, or Joint Patent, in each case that is exclusively licensed to EPIZYME
hereunder, or any claim of any of the foregoing; or 
 (b) actively assists any other Person (other than as may be necessary or
reasonably required to assert a cross-claim or a counter-claim or to respond to a court request or order or administrative law request or order) in bringing or prosecuting any action or proceeding (including any patent opposition or re-examination
proceeding) challenging or denying the validity of any of such Patents, in each case that are licensed exclusively to EPIZYME hereunder, or any claim thereof (each activity under the foregoing clause (a) or (b), an “EPIZYME Patent
Challenge”); 
 then GSK shall have the right to terminate this Agreement with respect to the Dropped Target(s) to which the EPIZYME
Patent Challenge relates (and all EPIZYME Compounds and EPIZYME Products directed to such Dropped Target(s), and all related EPIZYME Diagnostic Products), upon thirty (30) days’ written notice to EPIZYME; provided however
that, GSK’s right to terminate this Agreement under this Section 12.4 shall not apply to any Affiliate of EPIZYME that first becomes an Affiliate of EPIZYME after the Effective Date of this Agreement in connection with a merger or
acquisition event, where such Affiliate of EPIZYME was undertaking activities in connection with an EPIZYME Patent Challenge prior to such merger or acquisition event; provided however that EPIZYME causes such EPIZYME Patent
Challenge to terminate within [**] days after such merger or acquisition event. For the avoidance of doubt, an action by EPIZYME in defense of a Third Party opposition shall not constitute a challenge under this Section 12.4. 

12.5 Effects of Termination. 
 12.5.1 Termination by GSK for Convenience; Termination by EPIZYME for Cause or for Patent Challenge. If (x) this Agreement is terminated by EPIZYME in its entirety or with respect to one or
more Selected Targets as a result of GSK’s uncured material breach 

  
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pursuant to Section 12.3.1, (y) EPIZYME terminates this Agreement with respect to one or more Selected Targets as a result of a GSK Patent Challenge pursuant to Section 12.4.1, or
(z) GSK terminates this Agreement in its entirety or with respect to one or more Selected Targets for convenience pursuant to Section 12.2 (upon any termination under the foregoing clause (x), (y) or (z), each such terminated Selected
Target shall be deemed a “Terminated Target,” and all Licensed Compounds and Licensed Products directed to such Terminated Target, and all related Diagnostic Products, shall be deemed “Terminated Products”), then:

 (a) License Termination. All licenses granted to GSK under Section 5.1 of this Agreement with respect to the
Terminated Target(s) and Terminated Products shall be terminated and of no further force and effect. 
 (b) Summary of
Activities. Within [**] days after such termination, GSK shall provide to EPIZYME a reasonably accurate summary report of the status and results of its (and its Affiliates’ and Sublicensees’) material research, Development,
manufacturing and Commercialization activities directed to the Terminated Target(s) prior to the effective date of termination in the Field in the Territory. 
 (c) Transition Assistance. Without limiting the generality of the remainder of this Section 12.5.1, GSK shall [**], at [**], to effect a seamless, timely transition to EPIZYME of all research,
Development, manufacturing and Commercialization activities and responsibilities with respect to the Terminated Products in accordance with a transition plan to be mutually agreed by the Parties. 

(d) License Grant to EPIZYME. The licenses granted to EPIZYME pursuant to Section 5.2.2 above will survive any such
termination, subject to EPIZYME’s continued royalty payment obligations under Section 6.9 to the extent applicable. In addition, effective upon any such termination, GSK hereby grants to EPIZYME a perpetual, irrevocable, fully paid-up
license in the Field in the Territory, with the right to grant sublicenses, under all Patents and Know-How Controlled by GSK (including Collaboration IP and Joint IP) and used in the research, Development, manufacture or Commercialization of the
Terminated Product(s) as of the effective date of termination on a Terminated Target-by-Terminated Target basis: 
 (i) if this
Agreement is terminated during the Research Term for any Terminated Target, such license to EPIZYME shall be [**] as to such Terminated Target (and Terminated Product(s) directed to such Terminated Target) during the remainder of the Research Term;
and 
 (ii) if this Agreement is terminated after the end of the Research Term for any Terminated Target, such license to
EPIZYME shall be [**] as to such Terminated Target (and Terminated Product(s) directed to such Terminated Target) following the end of such Research Term, provided however that, such license shall remain [**] beyond the Research
Term (A) with respect to Collaboration IP Controlled by GSK and GSK’s interest in Joint IP, in each case that claim the [**] of any [**] directed to such Terminated Target, and (B) with respect to Diagnostic IP Controlled by GSK that
[**] that are related to any [**] for which EPIZYME is granted [**] under the foregoing subclause (A). 

  
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 (e) Exclusivity. The provisions of Article 7 notwithstanding, EPIZYME’s
exclusivity obligations with respect to the Terminated Target(s) under Section 7.1 shall expire as of the effective date of termination, and the exclusivity obligations of GSK under Section 7.1 with respect to such Terminated Target(s)
shall survive for a period of [**] after the effective date of termination. 
 (f) Clinical Development Activities.

 (i) With respect to any ongoing clinical trials of Terminated Products for which EPIZYME has not notified GSK prior to the
effective date of termination that it wishes to assume responsibility, GSK shall, at GSK’s cost and expense, complete such clinical trials only with regard to those patients enrolled at the date of termination and may otherwise cease enrollment
and cancel all cancelable expenses relating to such clinical trials. Notwithstanding the foregoing, GSK may prematurely suspend or terminate any such trial if (A) a priori protocol defined stopping rules are met for safety or efficacy or
(B) unacceptable safety signals are observed by GSK or the Data and Safety Monitoring Board with respect to any Terminated Product that present an unacceptable risk to patients participating in such trials; and 

(ii) With respect to any ongoing clinical trials of Terminated Products for which EPIZYME has notified GSK prior to the effective date
of termination that it wishes to assume responsibility, (A) each Party shall cooperate with the other Party to facilitate the orderly transfer to EPIZYME of the conduct of such clinical trials as soon as reasonably practicable after the
effective date of termination, (B) until such time as the conduct of such clinical trials has been successfully transferred to EPIZYME, GSK shall continue to conduct such clinical trials, (C) between the effective date of termination and
the date on which the conduct of such clinical trials has been successfully transferred to EPIZYME, EPIZYME shall be responsible for, and shall reimburse GSK with respect to, all costs and expenses reasonably incurred by GSK in the conduct of such
clinical trials during the foregoing transition period, and (D) following the date on which the conduct of such clinical trials has been successfully transferred to EPIZYME, EPIZYME shall be solely responsible for all costs and expenses of such
ongoing clinical trials. 
 (g) Regulatory Filings. To the extent permitted by applicable Law, GSK will promptly assign
to EPIZYME all Regulatory Approvals and Regulatory Materials for Terminated Products. If GSK is restricted under applicable Law from transferring ownership of any of the foregoing items to EPIZYME (including in order to continue to conduct any
transition activities as contemplated in this Section 12.5.1, including the conduct of clinical Development activities, if applicable, pursuant to Section 12.5.1(f) above), GSK shall grant EPIZYME (or its designee) a right of reference or
use to such item (it being understood that GSK shall use Commercially Reasonable Efforts to transfer the same to EPIZYME after the completion of such transition activities). GSK shall take all actions reasonably necessary to effect such transfer or
grant of right of reference or use to EPIZYME, including by making such filings as may be required with Regulatory Authorities in the Territory that may be necessary to record such assignment or effect such transfer and, at EPIZYME’s request,
complete any pending regulatory filings with respect to all applicable Terminated Products. 

  
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 (h) No Marketing-Related Materials. No promotional materials Controlled by GSK as of
the Effective Date that are used in the marketing, promotion or sale of Terminated Products shall be required to be transferred by GSK to EPIZYME. 
 (i) Trademarks. If the First Commercial Sale of any Terminated Product(s) has occurred as of the effective date of termination with respect to such Terminated Product(s), at EPIZYME’s request,
GSK will assign to EPIZYME any GSK trademark(s) used with respect to such Terminated Product(s) (other than GSK’s company-specific names, such as “GSK” and “GLAXOSMITHKLINE”), provided however that such
trademark(s) are neither (A) used for any other products in GSK’s portfolio nor (B) in GSK’s reasonable opinion confusingly similar to any other trade mark used for any other products in GSK’s portfolio. 

(j) Transfer of Data. Upon EPIZYME’s request, GSK will promptly assign to EPIZYME its entire right, title, and interest in
and to all pharmacological, toxicological and clinical test data and results, research data, reports and batch records, safety data and all other data, including CMC-related information, formulation information, chemistry and biology data,
Controlled by GSK as of the effective date of termination and generated in the research, Development, manufacture or Commercialization of the Terminated Product(s), but only to the extent solely pertaining to the Terminated Product(s) and not being
used in or having application to the research, Development, manufacture or Commercialization of any Licensed Compound or Licensed Product directed to a Selected Target that is not being terminated, or any other proprietary compound or product of
GSK. 
 (k) Contracts. GSK shall use Commercially Reasonable Efforts to assign to EPIZYME, to the extent assignable and
included in the transition plan to be agreed by the Parties under clause (c) above, GSK’s rights in Third Party agreements for licenses, services or supplies that are solely used in connection with the research, Development, manufacture or
Commercialization of Terminated Products, including any Third Party manufacturing agreements and clinical trial agreements (subject to clause (f) above), in each case to the extent (if at all) permitted under the terms and conditions of such
contracts. To the extent that any such agreement is not assignable by GSK, then such agreement will not be assigned, and upon the request of EPIZYME, GSK will cooperate in good faith and use Commercially Reasonable Efforts to allow EPIZYME to obtain
and enjoy the benefits of such agreement in the form of a license or other right to the extent held by GSK and subject to such Third Party’s rights, in each case to the extent (if at all) permitted under the terms and conditions of such
contracts. EPIZYME shall be solely responsible for any and all costs, expenses and liabilities of any kind arising in connection with any such contract assignment or extension of license or other rights to EPIZYME under this subsection (k) or
EPIZYME’s holding or use of such assigned contracts or rights licensed or otherwise provided to EPIZYME under this subsection (k). 
 (l) Manufacturing. Upon EPIZYME’s request, GSK shall, as part of the transition plan to be mutually agreed by the Parties under clause (c) above, transfer to EPIZYME (or its designee) any
processes, documents, materials and other Know-How, to the extent the foregoing is Controlled by GSK as of the effective date of termination and used in the manufacture of Terminated Products in the Field as of the effective date of termination;
provided however that, GSK will, upon EPIZYME’s request and pursuant to a supply agreement to be 

  
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negotiated in good faith by the Parties, at the transfer price paid by GSK for the applicable Terminated Product plus [**] percent ([**]%) if GSK sources such Terminated Product from a Third
Party, or at GSK’s direct manufacturing cost plus [**] percent ([**]%) if GSK or any of its Affiliates manufactures the applicable Terminated Product, continue to supply EPIZYME with clinical and commercial quantities of such Terminated Product
in the dosage strength, formulation and presentation under Development or being Commercialized by GSK, in either case, as of the effective date of termination, until the earlier of: (i) [**] months after the effective date of termination; or
(ii) establishment by EPIZYME of an alternative supply for such Terminated Product. 
 (m) Existing Inventory. At
EPIZYME’s election, GSK will transfer to EPIZYME such portion of GSK’s existing inventory of Terminated Products (including clinical trial materials and synthetic intermediates, if applicable) that EPIZYME elects and, with respect to any
commercial supply, that is in good and saleable condition, in its original, unopened packaging, at the transfer price paid by GSK for such Terminated Product if GSK sourced such Terminated Product from a Third Party, plus [**] percent ([**]%) or at
GSK’s direct manufacturing cost plus [**] percent ([**]%) if GSK or any of its Affiliates manufactured the Terminated Product. 
 (n) Prosecution and Enforcement. The provisions of Article 8 shall be terminated, except Section 8.1, Section 8.2.5 and Section 8.5.4. In addition, to the extent that any Patents
Controlled by GSK are exclusively licensed to EPIZYME pursuant to clause (d) above, as between the Parties, EPIZYME shall have the sole right (but not the obligation) to prosecute, maintain and enforce all Patents that relate to Terminated
Target(s) or Terminated Products, and GSK shall provide such assistance and cooperation as may be reasonably necessary in connection with the transition of prosecution and enforcement responsibilities to EPIZYME with respect to such Patents,
including execution of such documents as may be necessary to effect such transition. 
 Notwithstanding the foregoing provisions of this
Section 12.5.1, if GSK terminates the Agreement in its entirety or with respect to all Licensed Products against one or more but not all Selected Targets in accordance with Section 12.2 as a result of material safety concerns that GSK in
good faith determines make the further Development or Commercialization of the applicable Licensed Product(s) unreasonable from a scientific, regulatory or ethical perspective (without regard to commercial potential), then the foregoing clauses (c),
(d), (f), (g), (i), (j), (k), (l) and (m) of this Section 12.5.1 shall not apply to such Licensed Product(s); provided that, GSK, for itself and its Affiliates, hereby covenants and agrees not to assert any Patent rights
Controlled by GSK or its Affiliates against EPIZYME or its Affiliates, or any of their successors, assigns, (sub)licensees, distributors, manufacturers or customer with respect to the manufacture, use, offer for sale, sale or importation of such
Licensed Product. 
 12.5.2 Termination by GSK for Cause. If GSK terminates this Agreement in its entirety or with
respect to one or more Selected Target(s) pursuant to Section 12.3.1 as a result of EPIZYME’s uncured material breach, then the provisions of this Section 12.5.2 shall apply. 

  
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 (a) The licenses granted to GSK pursuant to Section 5.1 above with respect to the
applicable Selected Target(s) will survive any such termination and will convert to irrevocable exclusive licenses, with the right to sublicense in multiple tiers, subject to GSK’s continued payment obligations under Article 6 (including
royalties and milestones); provided however that, if this Agreement is terminated by GSK (either in its entirety or with respect to one or more Selected Target(s)) as a result of an uncured material breach by EPIZYME of its
obligations during the Research Term, then the milestone payments set forth in Section 6.4 or row (1), (2), (3) or (4) of the table in Section 6.5 shall be eliminated and all other milestone payments shall be reduced to eighty
percent (80%) of the otherwise applicable milestone amount, in each case to the extent relating to the applicable Selected Target(s) and not earned prior to such termination. 

(b) The licenses granted by GSK to EPIZYME pursuant to Section 5.2.2 shall survive any such termination, subject to EPIZYME’s
continued royalty payment obligations under Section 6.9 to the extent applicable. 
 (c) Section 5.5 shall continue
to apply in accordance with its terms. 
 (d) GSK shall have the right to pursue any further remedies that may be available to
it hereunder or at law or in equity. 
 12.5.3 Termination by GSK for Patent Challenge. If GSK terminates this Agreement
with respect to one or more Dropped Targets as a result of an EPIZYME Patent Challenge pursuant to Section 12.4.2, each such terminated Dropped Target shall be deemed a “Terminated Dropped Target”, and all EPIZYME Compounds and
EPIZYME Products directed to such Terminated Target, and all related EPIZYME Diagnostic Products, shall be deemed “Terminated EPIZYME Products”), then: 
 (a) All licenses granted to EPIZYME under Section 5.2.2 of this Agreement with respect to the Terminated Dropped Target(s) and Terminated EPIZYME Products shall be terminated and of no further force
and effect; and 
 (b) Such EPIZYME Patent Challenge shall be deemed to be a material breach of this Agreement by EPIZYME, and
GSK shall have the right to pursue any further remedies that may be available to it hereunder or at law or in equity. 
 12.6
Accrued Rights; Surviving Provisions. 
 12.6.1 Termination, relinquishment or expiration of this Agreement for any
reason shall be without prejudice to any rights that shall have accrued to the benefit of any Party prior to such termination, relinquishment or expiration, including the payment obligations under Article 6 hereof, and any and all damages or
remedies arising from any breach hereunder. Such termination, relinquishment or expiration shall not relieve any Party from obligations which are expressly indicated to survive termination of this Agreement. 

12.6.2 The provisions of Sections 5.3, 5.4, 8.1, 10.4, 12.1.2, 12.5 and 12.6, and Articles 1 (to the extent definitions are required to
interpret the surviving provisions of this 

  
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Agreement), 6 (to the extent due but unpaid as of the effective date of termination and to the extent the provisions of Article 6 relate to payment obligations that otherwise survive pursuant to
Section 12.5), 8 (with respect to the provisions related to ongoing activities related to Joint Patents), 9, 11 and 13 shall survive the termination of this Agreement in its entirety or expiration of this Agreement for any reason, in accordance
with their respective terms and conditions, and for the duration stated, and where no duration is stated, shall survive indefinitely. Article 9 shall survive for a period of [**] years after the effective date of termination of this Agreement.

 ARTICLE 13 
 MISCELLANEOUS 
 13.1 Dispute Resolution. If a dispute between the
Parties arises under this Agreement, either Party shall have the right to refer such dispute in writing to the respective Executive Officers, and such Executive Officers shall attempt in good faith to resolve such dispute. If the Parties are unable
to resolve a given dispute pursuant to this Section 13.1 within [**] days after referring such dispute to the Executive Officers, either Party may have the given dispute settled by binding arbitration pursuant to Section 13.2. 

13.2 Arbitration Request. If a Party intends to begin an arbitration to resolve a dispute arising under this Agreement, such Party
shall provide written notice (the “Arbitration Request”) to the other Party of such intention and a statement of the issues for resolution. From the date of the Arbitration Request and until such time as the dispute has become
finally settled, the running of the time periods as to which the other Party must cure a breach of this Agreement becomes suspended as to any breach that is the subject matter of the dispute. 

13.2.1 Additional Issues. Within [**] days after the receipt of the Arbitration Request, the other Party may, by written notice,
add additional issues for resolution in a statement of counter-issues. 
 13.2.2 No Arbitration of Patent Issues. Except
as otherwise set forth in Section 4.4, any dispute, controversy or claim relating to the scope, validity, enforceability or infringement of any Patents Covering the Development, manufacture, use, importation, offer for sale or sale of Licensed
Products shall be submitted to a court of competent jurisdiction in the country in which such patent rights were granted or arose. 
 13.2.3 Arbitration Procedure. Any arbitration pursuant to this Article 13 will be held in New York, New York, United States unless another location is mutually agreed by the Parties. The
arbitration will be governed by the United States Arbitration Act, 9 U.S.C. §§ 1-16, to the exclusion of any inconsistent state Law. The Parties shall mutually agree on the rules to govern discovery and the rules of evidence for the
arbitration within [**] days after the Arbitration Request. If the Parties fail to timely agree to such rules, the United States Federal Rules of Civil Procedure will govern discovery and the United States Federal Rules of Evidence will govern
evidence for the arbitration. The arbitration will be conducted by a single arbitrator knowledgeable in the subject matter at issue in the dispute and acceptable to both Parties; provided however that, the Parties may by mutual
agreement elect to have the arbitration conducted by a panel of three (3) arbitrators. If the Parties fail to agree on a mutually acceptable 

  
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arbitrator within [**] days after the Arbitration Request, then the arbitrator shall be selected by the New York, New York office of the AAA. The arbitrator may proceed to an award,
notwithstanding the failure of either Party to participate in the proceedings. The arbitrator shall, within [**] days after the conclusion of the arbitration hearing, issue a written award and statement of decision describing the essential findings
and conclusions on which the award is based, including the calculation of any damages awarded. The arbitrator shall be limited in the scope of his or her authority to resolving only the specific matter which the Parties have referred to arbitration
for resolution and shall not have authority to render any decision or award on any other issues. Subject to Section 11.5, the arbitrator shall be authorized to award compensatory damages, but shall not be authorized to award punitive, special,
consequential, or any other similar form of damages, or to reform, modify or materially change this Agreement. The arbitrator also shall be authorized to grant any temporary, preliminary or permanent equitable remedy or relief the arbitrator deems
just and equitable and within the scope of this Agreement, including an injunction or order for specific performance. The award of the arbitrator shall be the sole and exclusive remedy of the Parties, except for those remedies that are set forth in
this Agreement or which apply to a Party by operation of the applicable provisions of this Agreement, and the Parties hereby expressly agree to waive the right to appeal from the decisions of the arbitrator, and there shall be no appeal to any court
or other authority (government or private) from the decision of the arbitrator. Judgment on the award rendered by the arbitrator may be enforced in any court having competent jurisdiction thereof, subject only to revocation of the award on grounds
set forth in the United Nations Convention on the Recognition and Enforcement of Foreign Arbitral Awards. 
 13.2.4
Costs. Each Party shall bear its own attorneys’ fees, costs, and disbursements arising out of the arbitration, and shall pay an equal share of the fees and costs of the arbitrator; provided however that the
arbitrator, in his or her award, shall be authorized to determine whether a Party is the prevailing Party, and if so, to award to that prevailing Party reimbursement for its reasonable attorneys’ fees, costs and disbursements (including, for
example, expert witness fees and expenses, transcripts, photocopy charges and travel expenses). 
 13.2.5 Preliminary
Injunctions. Notwithstanding anything in this Agreement to the contrary, a Party may seek a temporary restraining order or a preliminary injunction from any court of competent jurisdiction in order to prevent immediate and irreparable injury,
loss, or damage on a provisional basis, pending the award of the arbitrator on the ultimate merits of any dispute. 
 13.2.6
Confidentiality. All proceedings and decisions of the arbitrator shall be deemed Confidential Information of each of the Parties, and shall be subject to Article 9. 
 13.3 Governing Law. This Agreement and any dispute arising from the performance or breach hereof shall be governed by and construed and enforced in accordance with the Laws of the State of New York
without reference to conflicts of laws principles; provided however that with respect to matters involving the enforcement of intellectual property rights, the Laws of the applicable country shall apply. The provisions of the
United Nations Convention on Contracts for the International Sale of Goods shall not apply to this Agreement or any subject matter hereof. 

  
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 13.4 Assignment. Neither Party may assign this Agreement without the consent of the
other Party, except as otherwise provided in this Section 13.4. Either Party may assign this Agreement in whole or in part to any Affiliate of such Party without the consent of the other Party; provided however that, such
assigning Party provides the other Party with written notice of such assignment and the assignee agrees in writing to assume performance of all assigned obligations. Further, subject to the remainder of this Section 13.4, each Party may assign
this Agreement, and all of its rights and obligations hereunder, without the consent of the other Party to its successor in interest by way of merger, acquisition, or sale of all or substantially all of its business or assets to which this Agreement
relates; provided however that, such assigning Party provides the other Party with written notice of such assignment and the assignee agrees in writing to assume performance of all assigned obligations. The assigning Party shall
remain primarily liable for the performance of its obligations under this Agreement by its assignees. The terms of this Agreement shall be binding upon and shall inure to the benefit of the successors, heirs, administrators and permitted assigns of
the Parties. Any purported assignment in violation of this Section 13.4 shall be null and void. 
 13.5 Performance
Warranty. Each Party hereby acknowledges and agrees that it shall be responsible for the full and timely performance as and when due under, and observance of all the covenants, terms, conditions and agreements set forth in this, Agreement by its
Affiliate(s) and Sublicensees. 
 13.6 Force Majeure. No Party shall be held liable or responsible to the other Party nor
be deemed to be in default under, or in breach of any provision of, this Agreement for failure or delay in fulfilling or performing any obligation of this Agreement when such failure or delay is due to force majeure, and without the fault or
negligence of the Party so failing or delaying. For purposes of this Agreement, force majeure is defined as causes beyond the control of the Party, including acts of God; material changes in Law; war; civil commotion; destruction of production
facilities or materials by fire, flood, earthquake, explosion or storm; labor disturbances; epidemic; and failure of public utilities or common carriers. In such event EPIZYME or GSK, as the case may be, shall immediately notify the other Party of
such inability and of the period for which such inability is expected to continue. The Party giving such notice shall thereupon be excused from such of its obligations under this Agreement as it is thereby disabled from performing for so long as it
is so disabled for up to a maximum of ninety (90) days, after which time EPIZYME and GSK shall promptly meet to discuss in good faith how to best proceed in a manner that maintains and abides by the Agreement. To the extent possible, each Party
shall use reasonable efforts to minimize the duration of any force majeure. 

  
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 13.7 Notices. Any notice or request required or permitted to be given under or in
connection with this Agreement shall be deemed to have been sufficiently given if in writing and personally delivered or sent by certified mail (return receipt requested), facsimile transmission (receipt verified), or overnight express courier
service (signature required), prepaid, to the Party for which such notice is intended, at the address set forth for such Party below: 
 If to EPIZYME, 
  

			
	addressed to:	  	Epizyme, Inc.
		  	840 Memorial Drive
		  	Cambridge, Massachusetts 02139
		  	Attention: Chief Business Officer
		  	Telephone: (617) 500-0712
		  	Facsimile: (617) 349-0707
		
	with a copy to:	  	 WilmerHale LLP
 60 State
Street
 Boston, MA 02109

		  	Attention: David E. Redlick, Esq.
		  	 Steven D. Barrett, Esq.

		  	Telephone: (617) 526-6000
		  	Facsimile: (617) 526-5000
		
	If to GSK,	  	
		
	addressed to:	  	Attention: Senior Vice President, Worldwide Business Development
		  	GlaxoSmithKline
		  	709 Swedeland Road
		  	P.O. Box 1539, MC UW2318
		  	King of Prussia, PA 19406-0939
		  	United States
		  	Telephone: (610) 270-7769
		  	Facsimile: (610) 270-6299
		
	with a copy to:	  	Attention: Vice President and Associate General Counsel,
		  	R&D Legal Operations
		  	GlaxoSmithKline
		  	2301 Renaissance Boulevard
		  	Mail Code RN0220
		  	King of Prussia, PA 19406
		  	Telephone: (610) 787-3630
		  	Facsimile: (610) 787-7084

 or to such other address for such Party as it shall have specified by like notice to the other Party; provided
however that notices of a change of address shall be effective only upon receipt thereof. If delivered personally or by facsimile transmission, the date of delivery shall be deemed to be the date on which such notice or request was
given. If sent by overnight express courier service, the date of delivery shall be deemed to be the next Business Day after such notice or request was deposited with such service. If sent by certified mail, the date of delivery shall be deemed to be
the third (3rd) Business Day after such notice or request was deposited with the U.S. Postal Service. 

  
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 13.8 Export Clause. Each Party acknowledges that the Laws of the United States
restrict the export and re-export of commodities and technical data of United States origin. Each Party agrees that it will not export or re-export restricted commodities or the technical data of the other party in any form without the appropriate
United States and foreign government licenses. 
 13.9 Waiver. Neither Party may waive or release any of its rights or
interests in this Agreement except in writing. The failure of either Party to assert a right hereunder or to insist upon compliance with any term of this Agreement shall not constitute a waiver of that right or excuse a similar subsequent failure to
perform any such term or condition. No waiver by either Party of any condition or term in any one or more instances shall be construed as a continuing waiver of such condition or term or of another condition or term. 

13.10 Severability. If any provision hereof should be held invalid, illegal or unenforceable in any jurisdiction, the Parties
shall negotiate in good faith a valid, legal and enforceable substitute provision that most nearly reflects the original intent of the Parties and all other provisions hereof shall remain in full force and effect in such jurisdiction and shall be
liberally construed in order to carry out the intentions of the Parties hereto as nearly as may be possible. Such invalidity, illegality or unenforceability shall not affect the validity, legality or enforceability of such provision in any other
jurisdiction. 
 13.11 Entire Agreement. This Agreement, together with the Exhibits hereto, set forth all the covenants,
promises, agreements, warranties, representations, conditions and understandings between the Parties and supersede and terminate all prior agreements and understanding between the Parties with respect to the subject matter of this Agreement. In
particular, and without limitation, this Agreement supersedes and replaces any and all term sheets relating to the transactions contemplated by this Agreement and exchanged between the Parties prior to the Effective Date. There are no covenants,
promises, agreements, warranties, representations, conditions or understandings, either oral or written, between the Parties with respect to the subject matter of this Agreement other than as set forth herein and therein. No subsequent alteration,
amendment, change or addition to this Agreement shall be binding upon the Parties unless reduced to writing and signed by the respective authorized officers of the Parties. 
 13.12 Independent Contractors. Nothing herein shall be construed to create any relationship of employer and employee, agent and principal, partnership or joint venture between the Parties. Each
Party is an independent contractor. Neither Party shall assume, either directly or indirectly, any liability of or for the other Party. Neither Party shall have the authority to bind or obligate the other Party and neither Party shall represent that
it has such authority. 
 13.13 Non-solicitation of Key Employees. During the period commencing on the Effective Date and
ending upon the end of the Advisory Period, neither Party shall solicit any Key Employee to leave the employment of the other Party and accept employment or work as a consultant with the soliciting Party. Notwithstanding the foregoing, nothing
herein shall restrict or preclude either Party’s right to make generalized searches for employees by way of a general solicitation for employment placed in a trade journal, newspaper or website. For purposes of this Section 13.13,
“Key Employee” means any employee who is material to the performance of the Collaboration hereunder, including any members of the JSC, JPT or any Subcommittee thereof, including without limitation the employees set forth on
Exhibit D. 

  
 - 72 -

 13.14 Headings; Construction; Interpretation. Headings used herein are for
convenience only and shall not in any way affect the construction of or be taken into consideration in interpreting this Agreement. The terms of this Agreement represent the results of negotiations between the Parties and their representatives, each
of which has been represented by counsel of its own choosing, and neither of which has acted under duress or compulsion, whether legal, economic or otherwise. Accordingly, the terms of this Agreement shall be interpreted and construed in accordance
with their usual and customary meanings, and each of the Parties hereto hereby waives the application in connection with the interpretation and construction of this Agreement of any rule of Law to the effect that ambiguous or conflicting terms or
provisions contained in this Agreement shall be interpreted or construed against the Party whose attorney prepared the executed draft or any earlier draft of this Agreement. Any reference in this Agreement to an Article, Section, subsection,
paragraph, clause, Schedule or Exhibit shall be deemed to be a reference to any Article, Section, subsection, paragraph, clause, Schedule or Exhibit, of or to, as the case may be, this Agreement. Except where the context otherwise requires,
(a) any definition of or reference to any agreement, instrument or other document refers to such agreement, instrument other document as from time to time amended, supplemented or otherwise modified (subject to any restrictions on such
amendments, supplements or modifications set forth herein or therein), (b) any reference to any Law refers to such Law as from time to time enacted, repealed or amended, (c) the words “herein,” “hereof” and
“hereunder,” and words of similar import, refer to this Agreement in its entirety and not to any particular provision hereof, (d) the words “include,” “includes,” “including,” “exclude,”
“excludes,” and “excluding,” shall be deemed to be followed by the phrase “but not limited to,” “without limitation” or words of similar import, and (e) the word “or” is used in the
inclusive sense (and/or). 
 13.15 Books and Records. Any books and records to be maintained under this Agreement by a
Party or its Affiliates or Sublicensees shall be maintained in accordance with U.S. generally accepted accounting principles (“GAAP”) in the case of EPIZYME, and shall be maintained in accordance with International Financial
Reporting Standards (“IFRS”) in the case of GSK, consistently applied, except that the same need not be audited. 
 13.16 Further Actions. Each Party shall execute, acknowledge and deliver such further instruments, and do all such other acts, as may be necessary or appropriate in order to carry out the expressly
stated purposes and the clear intent of this Agreement. 
 13.17 Parties in Interest. All of the terms and provisions of
this Agreement shall be binding upon, and shall inure to the benefit of and be enforceable by the Parties hereto and their respective successors, heirs, administrators and permitted assigns. 

13.18 Performance by Affiliates. To the extent that this Agreement imposes obligations on Affiliates of a Party, such Party agrees
to cause its Affiliates to perform such obligations. 

  
 - 73 -

 13.19 Counterparts. This Agreement may be signed in counterparts, each and every one
of which shall be deemed an original, notwithstanding variations in format or file designation which may result from the electronic transmission, storage and printing of copies from separate computers or printers. Facsimile signatures and signatures
transmitted via PDF shall be treated as original signatures. 
 [Signature page to follow]

  
 - 74 -

 IN WITNESS WHEREOF, and intending to be legally bound hereby, the Parties have caused this
Agreement to be executed by their duly authorized representatives as of the Effective Date. 
  

					
	Epizyme, Inc.
		
	By:	 	 /s/ Robert Gould

		 	Name:	 	Robert Gould
		 	Title:	 	President and CEO
	
	Glaxo Group Limited
		
	By:	 	 /s/ Paul Williamson

		 	Name:	 	Paul Williamson
		 	Title: Authorized Signatory For and on behalf of Edinburgh Pharmaceutical Industries Limited Corporate Director

 [Signature page to Collaboration and License Agreement] 

 EXHIBIT A 

EPIZYME Blocked Targets 

[**] 

  
 A - 1

 EXHIBIT B 

Initial Research Plan and Criteria 
  

											
	 Research Stage
	  	 Stage
Milestone
	  	 Desired Criteria to
Reach Milestone
	  	 Minimal Criteria to
Reach Milestone
	  	 Activities to be
Performed to
Reach
Milestone
	  	 Additional Key
Activities

	 Target Validation
	  	[**]	  	[**]	  		  	[**]	  	

  
 B - 1

											
						
	 Target-2-Hit
	  	[**]	  	[**]	  		  	[**]	  	[**]
						
	 Hit-2-Lead
	  	[**]	  	[**]	  		  	[**]	  	[**]
						
	 Hit-2-Lead Continued
	  		  		  		  		  	

  
 B - 2

											
						
	 Lead-2-Candidate
	  	[**]	  	[**]	  	[**]	  	[**]	  	
						
	 Lead-2-Candidate

Continued
	  		  		  		  		  	
						
	 Lead-2-Candidate

Continued
	  		  		  		  		  	
						
	 Lead-2-Candidate

Continued
	  		  		  		  		  	
						
	 Lead-2-Candidate

Continued
	  		  		  		  		  	
						
	 Lead-2-Candidate

Continued
	  		  		  		  		  	
						
	 IND Enabling Studies
	  	[**]	  	[**]	  		  	[**]	  	

  
 B - 3

 EXHIBIT C 

Policies 
 A.
Ethical Conduct Requirements 
 Ethical Conduct 
 The Parties are committed to the highest standards of conduct in all aspects of their respective businesses and to conduct their business with honesty and integrity, and in compliance with all applicable
legal and regulatory requirements. 
  

	 	•	 	 Always act with integrity and honesty and protect the Parties’ public image and reputation in relationships with customers, competitors,
suppliers, business partners and staff 

  

	 	•	 	 Promptly raise any concerns about possible unethical or illegal conduct 

 

	 	•	 	 Be free from actual or potential conflicts of interest that might influence, or appear to influence their judgment or actions when performing duties on
behalf of the Parties 

  

	 	•	 	 The Parties’ reputation and the respect of those who deal with the Parties must not be put at risk by acceptance of any entertainment, gifts or
favors intended or perceived by others to influence their business judgment 

  

	 	•	 	 Communications with external audiences, i.e., Investors and the Media, should be managed through appointed company spokespersons to minimize risk to
the Parties’ reputation 

  

	 	•	 	 Provide accurate and reliable information in records submitted, safeguard the Company’s confidential information, and respect the confidential
information of other parties with whom the Company does business or competes 

 Management of Human Safety Information

 The safeguarding of human subjects participating in clinical trials and patients who use devices or take investigational or licensed
medicinal products, certain consumer healthcare products, vaccines, or biological products (the foregoing collectively referred to as the “Products”) is of paramount importance. Products would also include blinded, placebo, or control
agents used in clinical studies. 
 Therefore, the Parties require a framework for management of Human Safety Information. The framework
includes, but is not limited to: 
  

	 	•	 	 Safety reviews of Products to evaluate emergent safety data 

 

	 	•	 	 Creation of appropriate committees and safety departments to proactively address human safety throughout Product development

  

	 	•	 	 Reporting of Human Safety Information to safety departments in a timely fashion. This includes any information relating to human health and/or
wellbeing arising following exposure of humans to products including reports of drug abuse or overdose, reports of drug interaction, or information received as part of product complaints 

  
 C-1

 Care and Ethical Treatment of Animals in Research 

 

	 	•	 	 Animals should be used in research only when required by regulatory authorities or where there are no alternatives through adherence to the
“3R” Principles—reducing the number of animals used, replacing animals with non-animal methods whenever possible and refining the research techniques used. In addition, the Parties include two more R’s: Responsibility and Respect
for animals involved in animal research. 

  

	 	•	 	 The Parties believe in using the highest standards for the humane care and treatment of all animals used in research, development and testing,
including adherence to the principles (listed below), and all applicable legal and regulatory requirements, with a default to which ever is more stringent. 

 

	 	•	 	 Access to species appropriate food and water 

  

	 	•	 	 Access to species specific housing, including species appropriate temperature and humidity levels 

 

	 	•	 	 Access to humane care and a program of veterinary care 

 

	 	•	 	 Animal housing that minimizes the development of abnormal behaviors and allows for normal species specific behavior, 

 

	 	•	 	 Adherence to principles of replacement, reduction and refinement in the design of in vivo studies 

 

	 	•	 	 Study design reviewed by institutional ethical review panel 

 

	 	•	 	 Commitment to minimizing pain and distress during in vivo studies 

 

	 	•	 	 Work performed by appropriately trained staff 

  

	 	•	 	 No Great Apes should be used for research 

 B. Requirements for Engaging External Experts and Healthcare Professionals 
 Use
of External Experts within R&D 
 The Parties believe that the engagement of external experts in R&D should be done in accordance
with the following principles: 
  

	 	•	 	 There must be a legitimate need for the services of the expert that cannot be fulfilled in-house, and the minimum number of experts needed should be
used 

  

	 	•	 	 Selection of experts should be based solely on the expert’s qualifications and expertise in the subject matter for which such expert is retained

  

	 	•	 	 The expert’s services must be documented in a written signed agreement 

 

	 	•	 	 Compensation must be based on fair market value for the services provided 

 

	 	•	 	 Reimbursement or pre-payment for costs associated with travel, lodging, meals and hospitality (i.e. refreshments, background music at meetings) for an
expert are acceptable if permitted by all law for the location in which the services are rendered and are modest in value 

  
 C-2

	 	•	 	 Experts shall not receive any gifts of any value, especially where the expert is also a healthcare professional 

 

	 	•	 	 Gift includes anything of value, regardless of amount, given to show friendship, appreciation, or support, including meals, entertainment or
recreational activities (excludes fair market value for services rendered). 

  

	 	•	 	 Healthcare Professionals includes, but is not limited to, physicians, their allied health professionals, and medical office staff. This term also
applies to pharmacists and employees of pharmacy benefit managers. 

 C. Requirements for Funding for Charitable
Donations and External Science/Medical Programs 
 Charitable Donations 
 Charitable donations to an eligible Health-Related Organization are allowed. Charitable donations of either funds or in-kind support are permitted if they are for the purpose of advancing the general
mission of an eligible, health-related recipient organization and if they are not tied or directed to a specific event or program. 
 To be
considered eligible for a donation, the health-related organization must meet all of the following: 
  

	 	•	 	 Non-profit organization 

  

	 	•	 	 The organization’s principle mission involves advancing science, medicine, or public health (collectively, a “health-related” mission)

  

	 	•	 	 The organization does not prescribe, purchase or recommend the Parties products, unless the request for a charitable donation for such an organization
is for a widely publicized fund-raising event or campaign in support of the health-related mission of the organization 

  

	 	•	 	 The organization, as well as its management and leadership, are independent of the control of the Parties or undue influence of any of the
Parties’ employees or agents 

 Even if the health-related organization is eligible to receive a charitable donation, the
donation may not be provided if a donation is intended: 
  

	 	•	 	 As a means of rewarding the prescribing, recommending, or use of the Parties products or services, including the influencing of formulary inclusion or
placement 

  

	 	•	 	 As a means of promoting the use of the Parties products or services. Return on investment (ROI) analyses are not permitted

  

	 	•	 	 As a means of supporting political causes or candidates 

 

	 	•	 	 As a means of supporting any organization or activity without a direct and bona fide scientific, medical, or public health purpose

  
 C-3

 General Requirements for US Independent Medical Education 

Funding for External Science/Medical Programs (FESMP) means financial support of specific activities intended to further the progress of science,
scientific/medical education, and the public health, for which the Parties will not take any intellectual property or other proprietary interest. 
  

	 	•	 	 A recipient of FESMP must be reasonably qualified to conduct high quality educational programs, research, or other activity being funded

  

	 	•	 	 FESMP is not permitted if used as a means of rewarding the prescribing, recommending, or use of the Parties products or services, including the
influencing of formulary inclusion/placement 

  

	 	•	 	 A recipient of FESMP must agree to make meaningful disclosure of any financial sponsorship from the partner 

 

	 	•	 	 FESMP may not be “expensed” or paid with the personal funds of an employee or contractor, and then reimbursed 

 

	 	•	 	 FESMP is not permitted as a means of supporting political causes or candidates 

 

	 	•	 	 FESMP is not permitted if used as a means of supporting any organization or activity without a direct and bona fide scientific, medical, or
public health purpose 

  

	 	•	 	 FESMP must comply with all substantive and procedural requirements established by the law where the program or activity potentially being funded will
take place 

 D. Clinical Research Requirements 
 Maintaining the Confidentiality of Protected Medical Information 
 The Parties respect the
confidential nature of protected medical information (PMI) originating from both healthy and patient volunteers involved in clinical, genetic, and other research work or from staff employed by the Parties. Therefore, a framework should be in place
to safeguard PMI against inappropriate collection, retention, use and disclosure (in addition to compliance with law and regulations). 

Safeguards include, but are not limited to: 
  

	 	•	 	 Collecting PMI only for specific and lawful purposes 

  

	 	•	 	 Collecting, retaining, using, reusing, and disclosing PMI only with valid consent or as otherwise permitted by law or regulation

  

	 	•	 	 PMI obtained from external sources is treated as a re-use and all reuse must be consistent with the original informed consent

  

	 	•	 	 Retention of PMI only for as long as business activities or scientific research requires and retention of only the minimum amount of identifying
information necessary 

  

	 	•	 	 Ensuring the physical and technological security of PMI 

 

	 	•	 	 Not using PMI in external publications 

  

	 	•	 	 Never transferring PMI from the pharmaceutical R&D division to the marketing function unless permission is obtained from the individual

  
 C-4

 If PMI is collected that indicates the need for immediate clinical intervention, that
information will be communicated to the study investigator or physician of record. 
 Personally Identifiable Information
(PII) means information which identifies a specific individual including but not limited to, name, address, and national identification numbers (e.g. Social Security Number) 
 Protected Medical Information (PMI) is PII that describes clinical and medical conditions, genetic status, treatment of conditions, health status, sexual orientation, ethnic origin, etc and
includes both encoded clinical trial data and overtly identifiable data. 
 Standards for Collecting, Obtaining and Using Human Biological
Samples in Research 
 The Parties respect the interest of donors of human biological samples used in research and require that certain
standards should apply to the collection, obtaining and use of such human biological samples, as set forth below. 
  

	 	•	 	 Ensure that samples are collected with informed consent and ethics committee/ Institutional Review Board (IRB) approval in accordance with the
applicable research requirements of Good Clinical Practice (International Conference on Harmonization). Additionally, through informed consent, donors must be made aware that the research is being undertaken by a commercial entity and that, where
applicable, the research involves the analysis of DNA and /or medical information. 

  

	 	•	 	 When obtaining samples from another entity that collected the samples for reasons unrelated to the Parties, confirmation that the entity complied with
relevant requirements for informed consent, ethics committee/IRB approval and data privacy is required 

  

	 	•	 	 Human biological samples must be used only for purposes that are consistent with the consent obtained and in compliance with relevant laws and
regulations 

  

	 	•	 	 Additional individual donor consent and ethics committee/IRB approval should be obtained when the research use intended is inconsistent with /beyond
the scope of the original consent. Additional consent should also be obtained if the original consent did not include analysis of DNA (if relevant to the research proposal) or use of any associated medical information (if relevant to the research
proposal). 

  

	 	•	 	 In general, cell lines (e.g. HeLa), derivatives (e.g. isolated proteins) and preparations of human biological materials (e.g. sub-cellular fractions)
that are well established and made available for research use, do not require re- consent and/or ethics committee/IRB approval for the intended research use 

 

	 	•	 	 Proposals to collect, obtain, or use human embryonic or foetal samples for research should be carefully reviewed and such research must have the
potential to benefit patients 

  
 C-5

 Conduct and Public Disclosure of Human Subject Research 

The Parties carry out human subject research in accordance with the ethical principles of respect for persons, beneficence, and justice. Such research
conforms to high ethical, medical and scientific standards. Specific principles for different types of human subject research are set forth below. 
 All Human Subject Research 
 All human subject research must be conducted in
accordance with the following principles: 
  

	 	•	 	 Human subject research is conducted in accordance with the ethical principles of respect for persons, beneficence and justice

  

	 	•	 	 Human subject research always has a legitimate scientific purpose and is not designed with the objective of rewarding healthcare professionals for
using, purchasing, recommending, or prescribing the Parties’ products 

  

	 	•	 	 Sales/marketing/commercial staff generally does not participate in the initiation or conduct of human subject research 

 

	 	•	 	 Placebo controlled studies are conducted only when there are scientifically sound methodological reasons, where the risks are minimized and reasonable
in relation to the knowledge gained, and when patients who receive placebo will not be subject to any additional risk of harm 

  

	 	•	 	 The standard of care required by the study design is, as a minimum, consistent with local standards of care 

 

	 	•	 	 Human subject research should be publicly disclosed and ideally published in the searchable, peer reviewed, scientific literature

 In most circumstances, summary protocols and summary results of clinical studies are posted on publicly
available registers and/or in the scientific literature within appropriate timelines. 
  

	 	•	 	 External proposals for additional analyses of human subject research studies are assessed for scientific merit and undertaken as collaborations between
in-house scientists and the proposer. 

  

	 	•	 	 Clinical studies are never terminated for solely financial reasons. 

 Interventional Human Subject Research 
 In addition to the foregoing general principles
applicable to all human subject research, the following principles apply to the conduct of Interventional Human Subject Research: 
  

	 	•	 	 Interventional human subject research is conducted in accordance with the ethical principles of the Declaration of Helsinki, the principles of ICH GCP
E6, ICH E11 (pediatrics) 

  
 C-6

	 	•	 	 Interventional studies of medicinal and other products are conducted in countries where the products are expected to be sold in and suitable for the
wider community of the country 

  

	 	•	 	 All interventional human subject research is conducted only with the approval of Institutional Review Boards or Independent Ethics Committees

  

	 	•	 	 When interventional human subject research is conducted in developing countries, the Parties seek agreement with key interested external parties in the
country on the conduct of the research, including the standard of care provided during the study, the scientific rationale for interventions, including placebo, the provision of healthcare for subjects after the study, and the fate of any capacity
built for the conduct of the study 

  

	 	•	 	 All interventional human subject research requires the informed consent of subjects (or their legal representative) who participate in the research

  

	 	•	 	 When nationally licensed medicinal products that are not the subject of the research study are required for the routine care of a patient during the
conduct of the study, the Parties only fund these when they are not funded by the normal healthcare infrastructure and there is assurance that they or suitable alternatives will be available and funded after the study while the medical need exists

  

	 	•	 	 For diseases/conditions that continue beyond the end of an interventional study, the Parties must be assured the healthcare system is able to provide,
and will take responsibility for, the continued care of study subjects 

  

	 	•	 	 When there is a compelling medical rationale for patients who have derived measurable medical benefit from an investigational medicinal product during
an interventional study to continue to receive that product after the study, the Parties endeavor to provide that treatment either through additional clinical studies or through expanded access programs 

 

	 	•	 	 The Parties provide investigators with the summary results of interventional studies in which they participate, and encourages investigators to inform
their subjects of the results 

 Meta-analyses and Pooled Analyses 

The following principles apply to research that uses data from more than one previously conducted clinical study (Meta-analyses and Pooled
Analyses): 
  

	 	•	 	 Research utilizing data from the Parties’ previous clinical studies in a manner inconsistent with, or beyond the scope of, the original informed
consent requires re-consent of the subjects, or if this is not practical, IRB/IEC approval. If this is not practical, the data are anonymized 

  

	 	•	 	 The Parties review, before submission for publication, any proposed manuscripts, presentations or abstracts prepared by research collaborators which
originate from the Parties human subject research studies (including the Parties supported studies) 

  
 C-7

 Non-Interventional (observational) Human Subject Research 

The following principles apply to Non-interventional (observational) human subject research: 

 

	 	•	 	 For observational studies where clinical data are collected by or on behalf of the Parties specifically for the purpose of the research, the Parties
abide by the local legal requirements and regulations for informed consent for the use of these data and IRB/IECs approval is obtained 

  

	 	•	 	 For observational studies using healthcare databases, the Parties are assured that there is compliance with relevant legal requirements for data
privacy and that patients have provided informed consent for the use of their data in research, or IRB/IEC approval has been obtained for that use; or other measures to protect privacy are in place (e.g. the data are anonymized)

  
 C-8

 EXHIBIT D 

Key Employees 
 EPIZYME
EMPLOYEES: 
 [**] 
 GSK EMPLOYEES:

 [**] 

  
 D-1

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