Document:

EX-10.4

 Exhibit 10.4 

As Amended as of August 19, 2020 

FOGHORN THERAPEUTICS INC. 

2016 STOCK INCENTIVE PLAN 

 

	1.	 Purpose 

The purpose of this 2016 Stock Incentive Plan (the “Plan”) of Foghorn Therapeutics Inc., a Delaware corporation (the
“Company”), is to advance the interests of the Company’s stockholders by enhancing the Company’s ability to attract, retain and motivate persons who are expected to make important contributions to the Company and by
providing such persons with equity ownership opportunities and performance-based incentives that are intended to better align the interests of such persons with those of the Company’s stockholders. Except where the context otherwise requires,
the term “Company” shall include any of the Company’s present or future parent or subsidiary corporations as defined in Sections 424(e) or (f) of the Internal Revenue Code of 1986, as amended, and any regulations
thereunder (the “Code”) and any other business venture (including, without limitation, joint venture or limited liability company) in which the Company has a controlling interest, as determined by the Board of Directors of the
Company (the “Board”); provided, however, that such other business ventures shall be limited to entities that, where required by Section 409A of the Code, are eligible issuers of service recipient stock (as
defined in Treas. Reg. Section 1.409A-1(b)(5)(iii)(E), or applicable successor regulation). 
  

	2.	 Eligibility 

All of the Company’s employees, officers and directors, as well as consultants and advisors to the Company (as such terms consultants and
advisors are defined and interpreted for purposes of Rule 701 under the Securities Act of 1933, as amended (the “Securities Act”) (or any successor rule)) are eligible to be granted Awards under the Plan. Each person who is granted
an Award under the Plan is deemed a “Participant.” “Award” means Options (as defined in Section 5), SARs (as defined in Section 6), Restricted Stock (as defined in Section 7), Restricted Stock Units
(as defined in Section 7) and Other Stock-Based Awards (as defined in Section 8). 
  

	3.	 Administration and Delegation 

(a) Administration by the Board. The Plan will be administered by the Board. The Board shall have authority to grant Awards and to
adopt, amend and repeal such administrative rules, guidelines and practices relating to the Plan as it shall deem advisable. The Board may construe and interpret the terms of the Plan and any Award agreements entered into under the Plan. The Board
may correct any defect, supply any omission or reconcile any inconsistency in the Plan or any Award in the manner and to the extent it shall deem expedient to carry the Plan into effect and it shall be the sole and final judge of such expediency.
All decisions by the Board shall be made in the Board’s sole discretion and shall be final and binding on all persons having or claiming any interest in the Plan or in any Award. 

(b) Appointment of Committees. To the extent permitted by applicable law, the Board may delegate any or all of its powers under the
Plan to one or more committees or subcommittees of the Board (each, a “Committee”). All references in the Plan to the “Board” shall mean the Board or a Committee of the Board to the extent that the Board’s
powers or authority under the Plan have been delegated to such Committee. 

	4.	 Stock Available for Awards 

(a) Number of Shares. Subject to adjustment under Section 9, Awards may be made under the Plan for up to 12,050,000 shares of
common stock, $0.0001 par value per share, of the Company (the “Common Stock”), any or all of which Awards may be in the form of Incentive Stock Options (as defined in Section 5(b)). If any Award expires or is terminated,
surrendered or canceled without having been fully exercised, is forfeited in whole or in part (including as the result of shares of Common Stock subject to such Award being repurchased by the Company at the original issuance price pursuant to a
contractual repurchase right), or results in any Common Stock not being issued, the unused Common Stock covered by such Award shall again be available for the grant of Awards under the Plan. Further, shares of Common Stock tendered to the Company by
a Participant to exercise an Award or to satisfy tax withholding obligations arising with respect to an Award shall be added to the number of shares of Common Stock available for the grant of Awards under the Plan. However, in the case of Incentive
Stock Options, the two immediately preceding sentences shall be subject to any limitations under the Code. Shares issued under the Plan may consist in whole or in part of authorized but unissued shares or treasury shares. 

(b) Substitute Awards. In connection with a merger or consolidation of an entity with the Company or the acquisition by the Company of
property or stock of an entity, the Board may grant Awards in substitution for any options or other stock or stock-based awards granted by such entity or an affiliate thereof. Substitute Awards may be granted on such terms as the Board deems
appropriate in the circumstances, notwithstanding any limitations on Awards contained in the Plan. Substitute Awards shall not count against the overall share limit set forth in Section 4(a), except as may be required by reason of
Section 422 and related provisions of the Code. 
  

	5.	 Stock Options 

(a) General. The Board may grant options to purchase Common Stock (each, an “Option”) and determine the number of
shares of Common Stock to be covered by each Option, the exercise price of each Option and the conditions and limitations applicable to the exercise of each Option, including conditions relating to applicable federal or state securities laws, as it
considers necessary or advisable. 
 (b) Incentive Stock Options. An Option that the Board intends to be an “incentive stock
option” as defined in Section 422 of the Code (an “Incentive Stock Option”) shall only be granted to employees of Foghorn Therapeutics Inc., any of Foghorn Therapeutics Inc.’s present or future parent or
subsidiary corporations as defined in Sections 424(e) or (f) of the Code, and any other entities the employees of which are eligible to receive Incentive Stock Options under the Code, and shall be subject to and shall be construed consistently
with the requirements of Section 422 of the Code. An Option that is not intended to be an Incentive Stock Option shall be designated a “Nonstatutory Stock Option.” The Company shall have no liability to a Participant, or
any other party, if an Option (or any part thereof) that is intended to be an Incentive Stock Option is not an Incentive Stock Option or if the Company converts an Incentive Stock Option to a Nonstatutory Stock Option. 

  
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 (c) Exercise Price. The Board shall establish the exercise price of each Option and
specify the exercise price in the applicable Option agreement. The exercise price shall be not less than 100% of the fair market value per share of Common Stock, as determined by (or in a manner approved by) the Board (“Fair Market
Value”), on the date the Option is granted. “Fair Market Value” of a share of Common Stock for purposes of the Plan will be determined as follows: 

(1) if the Common Stock is not publicly traded, the Board will determine the Fair Market Value for purposes of the Plan using any measure of
value it determines to be appropriate (including, as it considers appropriate, relying on appraisals) in a manner consistent with the valuation principles under Code Section 409A, except as the Board may expressly determine otherwise; 

(2) if the Common Stock trades on a national securities exchange, the closing sale price (for the primary trading session) on the date of
grant; or 
 (3) if the Common Stock does not trade on any such exchange, the average of the closing bid and asked prices as reported by an
authorized OTCBB market data vendor as listed on the OTCBB website (otcbb.com) on the date of grant. 
 For any date that is not a trading
day, the Fair Market Value of a share of Common Stock for such date will be determined by using the closing sale price or average of the bid and asked prices, as appropriate, for the immediately preceding trading day and with the timing in the
formulas above adjusted accordingly. The Board can substitute a particular time of day or other measure of “closing sale price” or “bid and asked prices” if appropriate because of exchange or market procedures or can, in its sole
discretion, use weighted averages either on a daily basis or such longer period as complies with Code Section 409A. 
 The Board has
sole discretion to determine the Fair Market Value for purposes of the Plan, and all Awards are conditioned on the participants’ agreement that the Administrator’s determination is conclusive and binding even though others might make a
different determination. 
 (d) Duration of Options. Each Option shall be exercisable at such times and subject to such terms and
conditions as the Board may specify in the applicable option agreement; provided, however, that no Option will be granted with a term in excess of ten (10) years. 

(e) Exercise of Options. Options may be exercised by delivery to the Company of a notice of exercise in a form of notice (which may be
electronic) approved by the Company, together with payment in full (in a manner specified in Section 5(f)) of the exercise price for the number of shares for which the Option is exercised. Shares of Common Stock subject to the Option will be
delivered by the Company as soon as practicable following exercise. 
 (f) Payment upon Exercise. Common Stock purchased upon the
exercise of an Option granted under the Plan shall be paid for as follows: 
 (1) in cash or by check, payable to the order of the Company;

 (2) when the Common Stock is registered under the Securities Exchange Act of 1934, as amended (the “Exchange Act”),
except as may otherwise be provided in the applicable 

  
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Option agreement or approved by the Board, in its sole discretion, by (i) delivery of an irrevocable and unconditional undertaking by a creditworthy broker to deliver promptly to the Company
sufficient funds to pay the exercise price and any required tax withholding or (ii) delivery by the Participant to the Company of a copy of irrevocable and unconditional instructions to a creditworthy broker to deliver promptly to the Company
cash or a check sufficient to pay the exercise price and any required tax withholding; 
 (3) when the Common Stock is registered under the
Exchange Act and to the extent provided for in the applicable Option agreement or approved by the Board, in its sole discretion, by delivery (either by actual delivery or attestation) of shares of Common Stock owned by the Participant valued at
their Fair Market Value, provided (i) such method of payment is then permitted under applicable law, (ii) such Common Stock, if acquired directly from the Company, was owned by the Participant for such minimum period of time, if
any, as may be established by the Board in its discretion and (iii) such Common Stock is not subject to any repurchase, forfeiture, unfulfilled vesting or other similar requirements; 

(4) to the extent provided for in the applicable Nonstatutory Stock Option agreement or approved by the Board in its sole discretion, by
delivery of a notice of “net exercise” to the Company, as a result of which the Participant would pay the exercise price for the portion of the Option being exercised by cancelling a portion of the Option for such number of shares as is
equal to the exercise price divided by the excess of the Fair Market Value on the date of exercise over the Option exercise price per share. 

(5) to the extent permitted by applicable law and provided for in the applicable Option agreement or approved by the Board, in its sole
discretion, by (i) delivery of a promissory note of the Participant to the Company on terms determined by the Board, or (ii) payment of such other lawful consideration as the Board may determine; or 

(6) by any combination of the above permitted forms of payment. 
  

	6.	 Stock Appreciation Rights 

(a) General. The Board may grant Awards consisting of stock appreciation rights (“SARs”) entitling the holder, upon
exercise, to receive an amount of Common Stock or cash or a combination thereof (such form to be determined by the Board) determined by reference to appreciation, from and after the date of grant, in the Fair Market Value of a share of Common Stock
over the measurement price established pursuant to Section 6(b). The date as of which such appreciation is determined shall be the exercise date. 

(b) Measurement Price. The Board shall establish the measurement price of each SAR and specify it in the applicable SAR agreement.
The measurement price shall not be less than 100% of the Fair Market Value on the date the SAR is granted. 
 (c) Duration of
SARs. Each SAR shall be exercisable at such times and subject to such terms and conditions as the Board may specify in the applicable SAR agreement; provided, however, that no SAR will be granted with a term in excess of ten
(10) years. 

  
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 (d) Exercise of SARs. SARs may be exercised by delivery to the Company of a notice of
exercise in a form (which may be electronic) approved by the Company, together with any other documents required by the Board. 
  

	7.	 Restricted Stock; Restricted Stock Units 

(a) General. The Board may grant Awards entitling recipients to acquire shares of Common Stock (“Restricted Stock”),
subject to the right of the Company to repurchase all or part of such shares at their issue price or other stated or formula price (or to require forfeiture of such shares if issued at no cost) from the recipient in the event that conditions
specified by the Board in the applicable Award are not satisfied prior to the end of the applicable restriction period or periods established by the Board for such Award. The Board may also grant Awards entitling the recipient to receive shares of
Common Stock or cash to be delivered at the time such Award vests (“Restricted Stock Units”) (Restricted Stock and Restricted Stock Units are each referred to herein as a “Restricted Stock Award”). 

(b) Terms and Conditions for All Restricted Stock Awards. The Board shall determine the terms and conditions of a Restricted Stock
Award, including the conditions for vesting and repurchase (or forfeiture) and the issue price, if any. 
 (c) Additional Provisions
Relating to Restricted Stock. 
 (1) Dividends. Unless otherwise provided in the applicable Award agreement, any dividends
(whether paid in cash, stock or property) declared and paid by the Company with respect to shares of Restricted Stock (“Accrued Dividends”) shall be paid to the Participant only if and when such shares become free from the
restrictions on transferability and forfeitability that apply to such shares. Each payment of Accrued Dividends will be made no later than the end of the calendar year in which the dividends are paid to stockholders of that class of stock or, if
later, the 15th day of the third month following the lapsing of the restrictions on transferability and the forfeitability provisions applicable to the underlying shares of Restricted Stock. 

(2) Stock Certificates. The Company may require that any stock certificates issued in respect of shares of Restricted Stock, as well as
dividends or distributions paid on such Restricted Stock, shall be deposited in escrow by the Participant, together with a stock power endorsed in blank, with the Company (or its designee). At the expiration of the applicable restriction periods,
the Company (or such designee) shall deliver the certificates no longer subject to such restrictions to the Participant or if the Participant has died, to Participant’s Designated Beneficiary. “Designated Beneficiary” means
(i) the beneficiary designated, in a manner determined by the Board, by a Participant to receive amounts due or exercise rights of the Participant in the event of the Participant’s death or (ii) in the absence of an effective
designation by a Participant, “Designated Beneficiary” the Participant’s estate. 
 (d) Additional Provisions
Relating to Restricted Stock Units. 
 (1) Settlement. Upon the vesting of and/or lapsing of any other restrictions (i.e.,
settlement) with respect to each Restricted Stock Unit, the Participant shall be entitled to receive from the Company one share of Common Stock or (if so provided in the applicable Award agreement) an amount of cash equal to the Fair Market Value of
one share of Common Stock. The 

  
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Board may, in its discretion, provide that settlement of Restricted Stock Units shall be deferred, on a mandatory basis or at the election of the Participant in a manner that complies with
Section 409A of the Code. 
 (2) Voting Rights. A Participant shall have no voting rights with respect to any Restricted Stock
Units. 
 (3) Dividend Equivalents. The Award agreement for Restricted Stock Units may provide Participants with the right to receive
an amount equal to any dividends or other distributions declared and paid on an equal number of outstanding shares of Common Stock (“Dividend Equivalents”). Dividend Equivalents may be paid currently or credited to an account for
the Participants, may be settled in cash and/or shares of Common Stock and may be subject to the same restrictions on transfer and forfeitability as the Restricted Stock Units with respect to which paid, in each case to the extent provided in the
applicable Award agreement. 
  

	8.	 Other Stock-Based Awards 

(a) General. Other Awards of shares of Common Stock, and other Awards that are valued in whole or in part by reference to, or are
otherwise based on, shares of Common Stock or other property, may be granted hereunder to Participants (“Other Stock-Based-Awards”). Such Other Stock-Based Awards shall also be available as a form of payment in the settlement of
other Awards granted under the Plan or as payment in lieu of compensation to which a Participant is otherwise entitled. Other Stock-Based Awards may be paid in shares of Common Stock or cash, as the Board shall determine. 

(b) Terms and Conditions. Subject to the provisions of the Plan, the Board shall determine the terms and conditions of each Other
Stock-Based Award, including any purchase price applicable thereto. 
  

	9.	 Adjustments for Changes in Common Stock and Certain Other Events 

(a) Changes in Capitalization. In the event of any stock split, reverse stock split, stock dividend, recapitalization, combination of
shares, reclassification of shares, spin-off or other similar change in capitalization or event, or any dividend or distribution to holders of Common Stock other than an ordinary cash dividend, (i) the
number and class of securities available under the Plan, (ii) the number and class of securities and exercise price per share of each outstanding Option, (iii) the share and per-share provisions and
the measurement price of each outstanding SAR, (iv) the number of shares subject to and the repurchase price per share subject to each outstanding Restricted Stock Award and (v) the share and
per-share-related provisions and the purchase price, if any, of each outstanding Other Stock-Based Award, shall be equitably adjusted by the Company (or substituted Awards may be made, if applicable) in the
manner determined by the Board. Without limiting the generality of the foregoing, in the event the Company effects a split of the Common Stock by means of a stock dividend and the exercise price of and the number of shares subject to an outstanding
Option are adjusted as of the date of the distribution of the dividend (rather than as of the record date for such dividend), then an optionee who exercises an Option between the record date and the distribution date for such stock dividend shall be
entitled to receive, on the distribution date, the stock dividend with respect to the shares of Common Stock acquired upon such Option exercise, notwithstanding the fact that such shares were not outstanding as of the close of business on the record
date for such stock dividend. 

  
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 (b) Reorganization Events. 

(1) Definition. A “Reorganization Event” shall mean: (a) any merger or consolidation of the Company with or into
another entity as a result of which all of the Common Stock of the Company is converted into or exchanged for the right to receive cash, securities or other property or is cancelled, (b) any transfer or disposition of all of the Common Stock of
the Company for cash, securities or other property pursuant to a share exchange or other transaction or (c) any liquidation or dissolution of the Company. 

(2) Consequences of a Reorganization Event on Awards Other than Restricted Stock. 

(i) In connection with a Reorganization Event, the Board may take any one or more of the following actions as to all or any (or any portion
of) outstanding Awards other than Restricted Stock on such terms as the Board determines (except to the extent specifically provided otherwise in an applicable Award agreement or another agreement between the Company and the Participant):
(i) provide that such Awards shall be assumed, or substantially equivalent Awards shall be substituted, by the acquiring or succeeding corporation (or an affiliate thereof), (ii) upon written notice to a Participant, provide that all of
the Participant’s unexercised Awards will terminate immediately prior to the consummation of such Reorganization Event unless exercised by the Participant (to the extent then exercisable) within a specified period following the date of such
notice, (iii) provide that outstanding Awards shall become exercisable, realizable, or deliverable, or restrictions applicable to an Award shall lapse, in whole or in part prior to or upon such Reorganization Event, (iv) in the event of a
Reorganization Event under the terms of which holders of Common Stock will receive upon consummation thereof a cash payment for each share surrendered in the Reorganization Event (the “Acquisition Price”), make or provide for a cash
payment to Participants with respect to each Award held by a Participant equal to (A) the number of shares of Common Stock subject to the vested portion of the Award (after giving effect to any acceleration of vesting that occurs upon or
immediately prior to such Reorganization Event) multiplied by (B) the excess, if any, of (I) the Acquisition Price over (II) the exercise, measurement or purchase price of such Award and any applicable tax withholdings, in exchange
for the termination of such Award, (v) provide that, in connection with a liquidation or dissolution of the Company, Awards shall convert into the right to receive liquidation proceeds (if applicable, net of the exercise, measurement or
purchase price thereof and any applicable tax withholdings) and (vi) any combination of the foregoing. In taking any of the actions permitted under this Section 9(b)(2), the Board shall not be obligated by the Plan to treat all Awards, all
Awards held by a Participant, or all Awards of the same type, identically. 
 (ii) Notwithstanding the terms of Section 9(b)(2)(i), in
the case of outstanding Restricted Stock Units that are subject to Section 409A of the Code: (i) if the applicable Restricted Stock Unit agreement provides that the Restricted Stock Units shall be settled upon a “change in control
event” within the meaning of Treasury Regulation Section 1.409A-3(i)(5)(i), and the Reorganization Event constitutes such a “change in control event”, then no assumption or substitution
shall be permitted pursuant to Section 9(b)(2)(i)(i) and the Restricted 

  
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Stock Units shall instead be settled in accordance with the terms of the applicable Restricted Stock Unit agreement; and (ii) the Board may only undertake the actions set forth in clauses
(iii), (iv) or (v) of Section 9(b)(2)(i) if the Reorganization Event constitutes a “change in control event” as defined under Treasury Regulation Section 1.409A-3(i)(5)(i) and such
action is permitted or required by Section 409A of the Code; if the Reorganization Event is not a “change in control event” as so defined or such action is not permitted or required by Section 409A of the Code, and the acquiring
or succeeding corporation does not assume or substitute the Restricted Stock Units pursuant to clause (i) of Section 9(b)(2)(i), then the unvested Restricted Stock Units shall terminate immediately prior to the consummation of the
Reorganization Event without any payment in exchange therefor. 
 (iii) For purposes of Section 9(b)(2)(i)(i), an Award (other than
Restricted Stock) shall be considered assumed if, following consummation of the Reorganization Event, such Award confers the right to purchase or receive pursuant to the terms of such Award, for each share of Common Stock subject to the Award
immediately prior to the consummation of the Reorganization Event, the consideration (whether cash, securities or other property) received as a result of the Reorganization Event by holders of Common Stock for each share of Common Stock held
immediately prior to the consummation of the Reorganization Event (and if holders were offered a choice of consideration, the type of consideration chosen by the holders of a majority of the outstanding shares of Common Stock); provided,
however, that if the consideration received as a result of the Reorganization Event is not solely common stock of the acquiring or succeeding corporation (or an affiliate thereof), the Company may, with the consent of the acquiring or succeeding
corporation, provide for the consideration to be received upon the exercise or settlement of the Award to consist solely of such number of shares of common stock of the acquiring or succeeding corporation (or an affiliate thereof) that the Board
determined to be equivalent in value (as of the date of such determination or another date specified by the Board) to the per share consideration received by holders of outstanding shares of Common Stock as a result of the Reorganization Event. 

(3) Consequences of a Reorganization Event on Restricted Stock. Upon the occurrence of a Reorganization Event other than a liquidation
or dissolution of the Company, the repurchase and other rights of the Company with respect to outstanding Restricted Stock shall inure to the benefit of the Company’s successor and shall, unless the Board determines otherwise, apply to the
cash, securities or other property which the Common Stock was converted into or exchanged for pursuant to such Reorganization Event in the same manner and to the same extent as they applied to such Restricted Stock; provided, however,
that the Board may provide for termination or deemed satisfaction of such repurchase or other rights under the instrument evidencing any Restricted Stock or any other agreement between a Participant and the Company, either initially or by amendment.
Upon the occurrence of a Reorganization Event involving the liquidation or dissolution of the Company, except to the extent specifically provided to the contrary in the instrument evidencing any Restricted Stock or any other agreement between a
Participant and the Company, all restrictions and conditions on all Restricted Stock then outstanding shall automatically be deemed terminated or satisfied. 

  
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	10.	 General Provisions Applicable to Awards. 

(a) Transferability of Awards. Awards (or any interest in an Award, including, prior to exercise, any interest in shares of Common Stock
issuable upon exercise of an Option or SAR) shall not be sold, assigned, transferred (including by establishing any short position, put equivalent position (as defined in Rule 16a-1 issued under the
Exchange Act) or call equivalent position (as defined in Rule 16a-1 issued under the Exchange Act)), pledged, hypothecated or otherwise encumbered by the person to whom they are granted, either voluntarily or
by operation of law, and, during the life of the Participant, shall be exercisable only by the Participant; except that Awards, other than Awards subject to Section 409A of the Code, may be transferred to family members (as defined in Rule
701(c)(3) under the Securities Act) through gifts or (other than Incentive Stock Options) domestic relations orders or to an executor or guardian upon the death or disability of the Participant. The Company shall not be required to recognize any
such permitted transfer until such time as such permitted transferee shall deliver to the Company a written instrument, as a condition to such transfer, in form and substance satisfactory to the Company confirming that such transferee shall be bound
by all of the terms and conditions of the Award. References to a Participant, to the extent relevant in the context, shall include references to authorized transferees. For the avoidance of doubt, nothing contained in this Section 10(a) shall
be deemed to restrict a transfer to the Company. 
 (b) Documentation. Each Award shall be evidenced in such form (written,
electronic or otherwise) as the Board shall determine. Each Award may contain terms and conditions in addition to those set forth in the Plan. 

(c) Board Discretion. Except as otherwise provided by the Plan, each Award may be made alone or in addition or in relation to any other
Award. The terms of each Award need not be identical, and the Board need not treat Participants uniformly. 
 (d) Termination of
Status. The Board shall determine the effect on an Award of the disability, death, termination or other cessation of employment, authorized leave of absence or other change in the employment or other status of a Participant and the extent to
which, and the period during which, the Participant, or the Participant’s legal representative, conservator, guardian or Designated Beneficiary, may exercise rights under the Award. 

(e) Withholding. The Participant must satisfy all applicable federal, state, and local or other income and employment tax withholding
obligations before the Company will deliver stock certificates or otherwise recognize ownership of Common Stock under an Award. The Company may decide to satisfy the withholding obligations through additional withholding on salary or wages. If the
Company elects not to or cannot withhold from other compensation, the Participant must pay the Company the full amount, if any, required for withholding or have a broker tender to the Company cash equal to the withholding obligations. Payment of
withholding obligations is due before the Company will issue any shares on exercise, vesting or release from forfeiture of an Award or at the same time as payment of the exercise or purchase price unless the Company determines otherwise. If provided
for in an Award or approved by the Board in its sole discretion, a Participant may satisfy such tax obligations in whole or in part by delivery (either by actual delivery or attestation) of shares of Common Stock, including shares retained from the
Award creating the tax obligation, valued at their Fair Market Value; provided, however, except as 

  
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otherwise provided by the Board, that the total tax withholding where stock is being used to satisfy such tax obligations cannot exceed the Company’s minimum statutory withholding
obligations (based on minimum statutory withholding rates for federal and state tax purposes, including payroll taxes, that are applicable to such supplemental taxable income). Shares used to satisfy tax withholding requirements cannot be subject to
any repurchase, forfeiture, unfulfilled vesting or other similar requirements. 
 (f) Amendment of Award. 

(1) The Board may amend, modify or terminate any outstanding Award, including but not limited to, substituting therefor another Award of the
same or a different type, changing the date of exercise or realization, and converting an Incentive Stock Option to a Nonstatutory Stock Option. The Participant’s consent to such action shall be required unless (i) the Board determines
that the action, taking into account any related action, does not materially and adversely affect the Participant’s rights under the Plan or (ii) the change is permitted under Section 9. 

(2) The Board may, without stockholder approval, amend any outstanding Award granted under the Plan to provide an exercise price per share
that is lower than the then-current exercise price per share of such outstanding Award. The Board may also, without stockholder approval, cancel any outstanding award (whether or not granted under the Plan) and grant in substitution therefor new
Awards under the Plan covering the same or a different number of shares of Common Stock and having an exercise price per share lower than the then-current exercise price per share of the cancelled award. 

(g) Conditions on Delivery of Stock. The Company will not be obligated to deliver any shares of Common Stock pursuant to the Plan or to
remove restrictions from shares previously issued or delivered under the Plan until (i) all conditions of the Award have been met or removed to the satisfaction of the Company, (ii) in the opinion of the Company’s counsel, all other
legal matters in connection with the issuance and delivery of such shares have been satisfied, including any applicable securities laws and regulations and any applicable stock exchange or stock market rules and regulations, and (iii) the
Participant has executed and delivered to the Company such representations or agreements as the Company may consider appropriate to satisfy the requirements of any applicable laws, rules or regulations. 

(h) Acceleration. The Board may at any time provide that any Award shall become immediately exercisable in whole or in part, free of
some or all restrictions or conditions, or otherwise realizable in whole or in part, as the case may be. 
  

	11.	 Miscellaneous. 

(a) No Right to Employment or Other Status. No person shall have any claim or right to be granted an Award by virtue of the adoption of
the Plan, and the grant of an Award shall not be construed as giving a Participant the right to continued employment or any other relationship with the Company. The Company expressly reserves the right at any time to dismiss or otherwise terminate
its relationship with a Participant free from any liability or claim under the Plan, except as expressly provided in the applicable Award. 

  
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 (b) No Rights as Stockholder. Subject to the provisions of the applicable Award, no
Participant or Designated Beneficiary shall have any rights as a stockholder with respect to any shares of Common Stock to be distributed with respect to an Award until becoming the record holder of such shares. 

(c) Effective Date and Term of Plan. The Plan shall become effective on the date on which it is adopted by the Board. No Awards shall
be granted under the Plan after the expiration of ten (10) years from the earlier of (i) the date on which the Plan was adopted by the Board or (ii) the date the Plan was approved by the Company’s stockholders, but Awards
previously granted may extend beyond that date. 
 (d) Amendment of Plan. The Board may amend, suspend or terminate the Plan or any
portion thereof at any time; provided that if at any time the approval of the Company’s stockholders is required as to any modification or amendment under Section 422 of the Code or any successor provision with respect to Incentive
Stock Options, the Board may not effect such modification or amendment without such approval. Unless otherwise specified in the amendment, any amendment to the Plan adopted in accordance with this Section 11(d) shall apply to, and be binding on
the holders of, all Awards outstanding under the Plan at the time the amendment is adopted, provided the Board determines that such amendment, taking into account any related action, does not materially and adversely affect the rights of
Participants under the Plan. 
 (e) Authorization of Sub-Plans (including Grants to non-U.S. Employees). The Board may from time to time establish one or more sub-plans under the Plan for purposes of satisfying applicable securities, tax or other laws of
various jurisdictions. The Board shall establish such sub-plans by adopting supplements to the Plan containing (i) such limitations on the Board’s discretion under the Plan as the Board deems
necessary or desirable or (ii) such additional terms and conditions not otherwise inconsistent with the Plan as the Board shall deem necessary or desirable. All supplements adopted by the Board shall be deemed to be part of the Plan, but each
supplement shall apply only to Participants within the affected jurisdiction and the Company shall not be required to provide copies of any supplement to Participants in any jurisdiction which is not the subject of such supplement. 

(f) Compliance with Section 409A of the Code. Except as provided in individual Award agreements initially or by
amendment, if and to the extent (i) any portion of any payment, compensation or other benefit provided to a Participant pursuant to the Plan in connection with Participant’s employment termination constitutes “nonqualified deferred
compensation” within the meaning of Section 409A of the Code and (ii) the Participant is a specified employee as defined in Section 409A(a)(2)(B)(i) of the Code, in each case as determined by the Company in accordance with its
procedures, by which determinations the Participant (through accepting the Award) agrees that the Participant is bound, such portion of the payment, compensation or other benefit shall not be paid before the day that is six months plus one
day after the date of “separation from service” (as determined under Section 409A of the Code) (the “New Payment Date”), except as Section 409A of the Code may then permit. The aggregate of any payments that
otherwise would have been paid to the Participant during the period between the date of separation from service and the New Payment Date shall be paid to the Participant in a lump sum on such New Payment Date, and any remaining payments will be paid
on their original schedule. 

  
 11 

 The Company makes no representations or warranty and shall have no liability to the Participant or any other
person if any provisions of or payments, compensation or other benefits under the Plan are determined to constitute nonqualified deferred compensation subject to Section 409A of the Code but do not to satisfy the conditions of that section.

 (g) Limitations on Liability. Notwithstanding any other provisions of the Plan, no individual acting as a director,
officer, other employee, or agent of the Company will be liable to any Participant, former Participant, spouse, beneficiary, or any other person for any claim, loss, liability, or expense incurred in connection with the Plan, nor will such
individual be personally liable with respect to the Plan because of any contract or other instrument such individual executes in such individual’s capacity as a director, officer, other employee, or agent of the Company. The Company will
indemnify and hold harmless each director, officer, other employee, or agent of the Company to whom any duty or power relating to the administration or interpretation of the Plan has been or will be delegated, against any cost or expense (including
attorneys’ fees) or liability (including any sum paid in settlement of a claim with the Board’s approval) arising out of any act or omission to act concerning the Plan unless arising out of such person’s own fraud or bad faith. 

(h) Governing Law. The provisions of the Plan and all Awards made hereunder shall be governed by and interpreted in accordance with the
laws of the State of Delaware, excluding choice-of-law principles of the law of such state that would require the application of the laws of a jurisdiction other than
the State of Delaware. 
 * * * * 

  
 12 

 FOGHORN THERAPEUTICS INC. 

2016 STOCK INCENTIVE PLAN 

CALIFORNIA SUPPLEMENT 

Pursuant to Section 11(e) of the Plan, the Board has adopted this supplement for purposes of satisfying the requirements of
Section 25102(o) of the California Law: 
 Any Awards granted under the Plan to a Participant who is a resident of the State of
California on the date of grant (a “California Participant”) shall be subject to the following additional limitations, terms and conditions: 

1. Additional Limitations on Options. 

(a) Maximum Duration of Options. No Options granted to California Participants shall have a term in excess of ten (10) years
measured from the Option grant date. 
 (b) Minimum Exercise Period Following Termination. Unless a California Participant’s
employment is terminated for cause (as defined by applicable law, the terms of the Plan or option grant or a contract of employment), in the event of termination of employment of such Participant, such Participant shall have the right to exercise an
Option, to the extent that such Participant is entitled to exercise such Option on the date employment terminated, until the earlier of: (i) at least six (6) months from the date of termination, if termination was caused by such
Participant’s death or disability, (ii) at least thirty (30) days from the date of termination, if termination was caused other than by such Participant’s death or disability and (iii) the Option expiration date. 

2. Additional Limitations for Other Stock-Based Awards. The terms of all Awards granted to a California Participant under Section 8 of the Plan
shall comply, to the extent applicable, with Sections 260.140.42, 260.140.45 and 260.140.46 of the California Code of Regulations. 
 3. Additional
Limitations on Timing of Awards. No Award granted to a California Participant shall become exercisable, vested or realizable, as applicable to such Award, unless the Plan has been approved by the holders of a majority of the Company’s
outstanding voting securities by the later of (i) within twelve (12) months before or after the date the Plan was adopted by the Board, or (ii) prior to or within twelve (12) months of the granting of any Award to a California
Participant. 
 4. Additional Restriction Regarding Recapitalizations, Stock Splits, Etc. For purposes of Section 9 of the Plan, in the event of
a stock split, reverse stock split, stock dividend, recapitalization, combination, reclassification or other distribution of the Company’s securities underlying the Award without the receipt of consideration by the Company, the number of
securities purchasable, and in the case of Options, the exercise price of such Options, must be proportionately adjusted. 
 5. Additional Limitations on
Transferability of Awards. Notwithstanding the provisions of Section 10(a) of the Plan, an Award granted to a California Participant may not be transferred to an executor or guardian upon the disability of the Participant. 

* * * * 

  
 13EX-10.5

 Exhibit 10.5 

STOCK RESTRICTION AGREEMENT 

This STOCK RESTRICTION AGREEMENT (this “Agreement”) is dated as of [Date] (the “Effective
Date”), between Foghorn Therapeutics Inc., a Delaware corporation (the “Company”), and [Name] (“Holder”) relating to shares of the Company’s common stock, par value $0.0001 per share
(“Common Stock”). The Company and Holder are each referred to individually as a “Party” and together as the “Parties.” 

WHEREAS, the Company and Holder have entered into that certain Nonstatutory Stock Option Agreement, dated as of the Effective Date, (as
it may be amended from time to time, the “Stock Option Agreement”), pursuant to which Holder is granted an option to purchase [Number] shares of Common Stock (the “Shares”) in accordance with the terms
set forth therein; and 
 WHEREAS, the Company and Holder desire to enter into this Agreement pursuant to which the Shares, upon
exercise, shall become subject to certain terms and conditions, as more fully described herein. 
 NOW, THEREFORE, in consideration
of the premises and the mutual covenants herein contained and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Company and Holder hereby agree as follows: 

ARTICLE I 
 RESTRICTED
SHARES 
 Upon execution of this Agreement, the Company and Holder agree that the Shares shall initially be deemed “Restricted
Shares” and shall initially be subject to all of the restrictions set forth herein. 
 ARTICLE II 

DEFINITIONS; INTERPRETATION 

Section 2.1. Definitions. For purposes of this Agreement, the following terms are defined as set forth below: 

(a) “Agreement” has the meaning set forth in the preamble. 

(b) “Board” means the Company’s board of directors 

(c) “Common Stock” has the meaning set forth in the preamble. 

(d) “Effective Date” has the meaning set forth in the preamble. 

(e) “Escrow Agent” has the meaning set forth in Section 5.6. 

(f) “Grant Date” has the meaning set forth in the Stock Option Agreement. 

 (g) “Party” has the meaning set forth in the preamble. 

(h) “Repurchase Price” means $0.0001 per share. 

(i) “Repurchase Event” has the meaning set forth in Section 5.2. 

(j) “Repurchase Period” has the meaning set forth in Section 5.2. 

(k) “Repurchase Right” has the meaning set forth in Section 5.1. 

(l) “Restricted Shares” means Shares that are not vested and are subject to the Repurchase Right (as defined
in Section 5.1). 
 (m) “Shares” has the meaning set forth in the recitals hereto. 

(n) “Stock Option Agreement” has the meaning set forth in the recitals. 

(o) “Unrestricted Shares” means Shares that are vested and are not subject to the Repurchase Right. 

Section 2.2. Interpretation. Except where the context expressly requires otherwise: 

(a) the words “include,” “includes” and “including” shall be deemed to be followed by the phrase
“without limitation;” and 
 (b) the words “herein” “hereof” and “hereunder,” and
words of similar import, shall be construed to refer to this Agreement in its entirety and not to any particular provision hereof. 

ARTICLE III 
 LAPSE OF
RESTRICTIONS 
 Section 3.1. Vesting Schedule. Except as otherwise provided in the Stock Option Agreement, twenty-five
percent (25%) of the Restricted Shares will vest and become Unrestricted Shares on the Grant Date and the remaining Restricted Shares will vest and become Unrestricted Shares as to six and one quarter percent (6.25%) of the total initial number of
Restricted Shares on the first day of each calendar quarter following the Grant Date for the subsequent twelve (12) calendar quarters in each case (rounded down to the nearest whole share, except as to the last vesting period, with respect to
which all remaining shares subject thereto will vest and become Unrestricted Shares), as long as Holder is a director of the Company on each such vesting date. No further action on behalf of the Company or Holder or any other person or entity shall
be required for Restricted Shares to become Unrestricted Shares under this Section 3.1 or the following Section 3.2. 

Section 3.2. Reorganization Event. Notwithstanding anything contained herein to the contrary, in the event of a Reorganization
Event (as defined in the Company’s 2016 Stock Incentive Plan), any and all Restricted Shares will automatically vest and become Unrestricted Shares immediately prior to such Reorganization Event, if Holder is a director of the Company
immediately prior to such Reorganization Event. 

  
 2 

 ARTICLE IV 

RESTRICTION ON TRANSFER 

Section 4.1. Restricted Shares. Holder may not directly or indirectly transfer, sell, assign, pledge, hypothecate or otherwise
dispose of any of the Restricted Shares, nor any interest therein, without the prior written consent of the Board or as otherwise provided in this Agreement. The Company shall not be required to (a) transfer any Restricted Shares on its books
that shall have been sold, assigned or otherwise transferred in violation of this Section 4.1 or (b) treat as the owner of such Restricted Shares, or accord the right to vote as such owner or to pay dividends to, any person or entity to
which any such Restricted Shares shall have been so sold, assigned or otherwise transferred, in violation of this Section 4.1. 

Section 4.2. Transferees. Notwithstanding anything contained in Section 4.1 to the contrary, Holder may transfer (i) any
or all of his Restricted Shares to his spouse, parents, siblings, or children or grandchildren, or to a trust established for the benefit of his spouse, parents, siblings, children or grandchildren, or Holder or (ii) any or all of the
Restricted Shares under his will or by the laws of intestacy, in each case of clauses (i) and (ii), provided that, such Restricted Shares shall remain subject to this Agreement 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. Notwithstanding the foregoing, the Restricted Shares shall continue to be the Restricted
Shares in the hands of any holder other than Holder, and except as otherwise expressly provided herein, each such other holder of Restricted Shares will succeed to all rights and obligations attributable to Holder as a holder of Restricted Shares
hereunder. 
 ARTICLE V 

REPURCHASE RIGHT 

Section 5.1. Scope of Repurchase Right. In the event that Holder ceases to be a director of the Company, the Restricted Shares
shall be subject to a right (but not an obligation) of repurchase by the Company, at a price and on the other terms and conditions set forth below (the “Repurchase Right”). Exercise by the Company of the Repurchase Right shall
require approval by a majority of the Board. 
 Section 5.2. Condition Precedent to Exercise. The Repurchase Right shall be
exercisable by the Company with respect to the Restricted Shares during the ninety (90)-day period (the “Repurchase Period”) immediately following the date that Holder ceases to be a director
of the Company (the “Repurchase Event”). 
 Section 5.3. Repurchase Cost. The purchase price for the Restricted
Shares to be paid by the Company pursuant to the Repurchase Right shall be an amount equal to the Repurchase Price. 
 Section 5.4.
Exercise of Repurchase Right. The Repurchase Right shall be exercisable by the Company only by written notice delivered to Holder prior to the expiration of the 

  
 3 

 
Repurchase Period. Each such notice shall set forth the date, time and place for the repurchase of the Restricted Shares, the number of Restricted Shares to be repurchased and the purchase price
therefor. Such date shall not be more than thirty (30) days after the date of the notice. Prior to the close of business on such date, Holder shall deliver to the Company certificate(s) representing the Restricted Shares to be repurchased and
properly endorsed for transfer to the Company. The Company shall promptly, but in no event later than the next business day, following the receipt of such certificate(s), pay to Holder the purchase price determined according to Section 5.3.
Such payment shall be made in one installment in immediately available funds. The right of repurchase shall terminate with respect to any Restricted Shares for which it has not been timely exercised pursuant to this Section 5.4. 

Section 5.5. Substituted Securities. In the event of a stock split, an adjustment in conversion ratio, a recapitalization or a
similar transaction affecting the Company’s outstanding securities without receipt of consideration, any substituted securities which are by reason of such transaction distributed with respect to any Restricted Shares, or into which such
Restricted Shares thereby become convertible, shall immediately be subject to Repurchase Right Appropriate adjustments to reflect the distribution of such securities or property shall be made to the number and/or class of the Restricted Shares.
After each such transaction, appropriate adjustments shall also be made to the price per share to be paid upon the exercise of Repurchase Right in order to reflect any change in the Company’s outstanding securities effected without receipt of
consideration therefor; provided, however, that the aggregate purchase price payable for the Restricted Shares shall remain the same. 

Section 5.6. Escrow. Upon the issuance of the certificates for Restricted Shares, such certificates shall be held in escrow by the
Company as the escrow agent (the “Escrow Agent”) until the Repurchase Period expires or the Restricted Shares are repurchased by the Company, in each case in accordance with this ARTICLE V. Upon the issuance of the certificates for
any substituted securities described in Section 5.5, Holder shall immediately deliver such certificates to the Company to be held in escrow. All regular cash dividends on Shares shall be paid directly to Holder and shall not be held in escrow.
Promptly following receipt by the Escrow Agent of a written request from Holder, the Company shall release from escrow and deliver to Holder a certificate for the whole number of Unrestricted Shares, if any. In the event of a repurchase by the
Company of Restricted Shares subject to the Repurchase Right, the Escrow Agent shall release from escrow and cancel a certificate for the number of Restricted Shares so repurchased. 

Section 5.7. Termination of Rights as Stockholder. Notwithstanding anything to the contrary herein, the Parties agree that, if the
Company makes available, at the time and place and in the amount and form described in Section 5.4, the consideration for the Restricted Shares to be repurchased in accordance with such notice and in compliance with this Agreement, then,
immediately after such time, Holder shall no longer have any rights as a holder of such Restricted Shares (other than the right to receive payment of such consideration in accordance with such notice). Such Restricted Shares shall be deemed to have
been repurchased in accordance with the applicable provisions hereof, whether or not the certificate(s) therefor have been delivered as required by such notice. 

  
 4 

 Section 5.8. Legend. All certificates representing the Restricted Shares shall
have endorsed thereon a legend substantially as follows: 
 “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO RESTRICTIONS SET
FORTH IN A STOCK RESTRICTION AGREEMENT DATED AS OF APRIL 5, 2017 WITH THE COMPANY, A COPY OF WHICH AGREEMENT IS AVAILABLE FOR INSPECTION AT THE OFFICES OF THE COMPANY OR WILL BE MADE AVAILABLE UPON REQUEST.” 

ARTICLE VI 

SECTION 83(B) ELECTION 

Holder understands that Section 83 of the Internal Revenue Code of 1986, as amended, may tax as compensation income the difference
between the amount paid for the Shares and the fair market value of the Shares as of the date any restrictions on Shares lapse in the absence of an 83(b) election. A form of 83(b) election is attached as Exhibit A. 

ARTICLE VII 

MISCELLANEOUS 

Section 7.1. Notices. Any notices, consents, or other communication required to be sent or given hereunder by any of the Parties
shall in every case be in writing and shall be deemed properly served if (a) delivered in hand personally, (b) sent by registered or certified mail, in all such cases with first class postage prepaid and return receipt requested,
(c) delivered by a recognized overnight courier service, freight prepaid or (d) sent by facsimile transmission, transmission confirmed (along with a copy sent by first-class mail), to the Parties at the addresses as set forth below or at
such other addresses or to the attention of such other person as may be furnished by prior written notice of the receiving Party to the sending Party: 
  

			
	if to the Company:	  	Foghorn Therapeutics Inc.
		  	161 First Street
		  	Cambridge, MA 02142
		  	Attention: President
		
	with a copy to:	  	Ropes & Gray LLP
		  	Prudential Tower
		  	800 Boylston Street
		  	Boston, MA 02110
		  	Fax:
		  	Attention:
		
	if to Holder:	  	[Holder]
		  	[Address]
		  	[Address]

 Date of service of such notice shall be (i) the date such notice is personally delivered by hand, (ii) five (5) days
after the date of mailing if sent by certified or registered mail, (iii) one (1) day after date of delivery to the overnight courier if sent by overnight courier or (iv) the next succeeding business day after transmission by facsimile,
transmission confirmed. 

  
 5 

 Section 7.2. Third-Party Beneficiaries. Nothing herein expressed or implied is
intended or shall be construed to confer upon or give to any person or entity, other than the Parties and their respective permitted successors and assigns, any rights or remedies under or by reason of this Agreement. 

Section 7.3. Consent of Spouse. If Holder is married as of the Effective Date, Holder’s spouse shall execute a Consent of
Spouse in the form of Exhibit B hereto, effective as of the Effective Date. Such consent shall not be deemed to confer or convey to the spouse any rights in the Restricted Shares that do not otherwise exist by operation of law or the express
written agreement of the Parties. If Holder marries or remarries subsequent to the Effective Date, Holder shall, not later than sixty (60) days thereafter, obtain his new spouse’s acknowledgment of and consent to the existence and binding
effect of all restrictions contained in this Agreement by such spouse’s executing and delivering a Consent of Spouse in the form of Exhibit B. 

Section 7.4. Severability. Whenever possible, each provision of this Agreement will be interpreted in such manner as to be
effective and valid under applicable law, but if any provision of this Agreement is held to be invalid, illegal or unenforceable in any respect under any applicable law or rule in any jurisdiction, such invalidity, illegality, or unenforceability
will not affect any other provision or any other jurisdiction, but this Agreement will be reformed, construed, and enforced in such jurisdiction as if such invalid, illegal, or unenforceable provision had never been contained herein. 

Section 7.5. Complete Agreement. This Agreement embodies the complete agreement and understanding between the Parties and
supersedes and preempts any prior understandings, agreements, or representations by or between the Parties, written or oral, which may have related to the subject matter hereof in any way. 

Section 7.6. Counterparts. This Agreement may be executed on separate counterparts, each of which is deemed to be an original and
all of which taken together constitute one and the same agreement. 
 Section 7.7. Successors and Assigns. This Agreement may
not be assigned by either Party without the prior written consent of the other Party. This Agreement is intended to bind and inure to the benefit of and be enforceable by Holder and the Company and their respective successors and assigns (including
subsequent holders of Common Stock). 
 Section 7.8. No Strict Construction. The language used in this Agreement will be deemed
to be the language chosen by the Parties to express their mutual intent, and no rule of strict construction will be applied against any Party. 

Section 7.9. Remedies. Each of the Parties will be entitled to enforce its rights under this Agreement specifically, to recover
damages by reason of any breach of any provision of this Agreement and to exercise all other rights existing in its favor. Holder and the Company agree and acknowledge that money damages will not be an adequate remedy for any breach by Holder of the
provisions of this Agreement and that the Company shall be entitled to specific performance and injunctive relief in order to enforce or prevent any violation of any provision of this Agreement in any court of competent jurisdiction. 

  
 6 

 Section 7.10. Amendments and Waivers. Any provision of this Agreement may be
amended or waived only with the prior written consent of the Company and Holder. 
 Section 7.11. Governing Law. This Agreement
shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts applicable to contracts made and to be performed wholly therein. Subject to Section 7.9, the Parties agree that jurisdiction and venue in any
action brought by any Party pursuant to this Agreement shall properly lie in any federal or state court located in the Commonwealth of Massachusetts and the Parties expressly submit to such jurisdiction. 

Section 7.12. Headings. The captions set forth in this Agreement are for convenience only and shall not be considered as part of
this Agreement or as in any way limiting the terms and provisions hereof. 
 (Signature page follows.) 

  
 7 

 IN WITNESS WHEREOF, the Parties have executed this Agreement on the day and year
first above written. 
  

					
	FOGHORN THERAPEUTICS INC.
		
	By:	 	  

		 	Name:	 	[Name]
		 	Title:	 	[Title]
	
	[HOLDER]
		
	By:	 	  

		 	Name:	 	[Name]

  
 (Signature Page to
Stock Restriction Agreement) 

 EXHIBIT A 

Election to Include Gross Income in Year 

of Transfer Pursuant to Section 83(b) 

of the Internal Revenue Code of 1986, as amended 

In accordance with Section 83(b) of the Internal Revenue Code of 1986, as amended (the “Code”), the undersigned (the
“Taxpayer”) hereby elects to include in her gross income as compensation for services the excess, if any, of the fair market value of the property (described below) at the time of transfer over the amount paid for such property.

 The following sets forth the information required in accordance with the Code and the regulations promulgated hereunder: 

 

	1.	 The name, address and social security number of the undersigned are: 

 

			
	Name:	 	  

		
	Address:	 	  

		
		 	  

			
		
	Social Security No.:	 	  

  

	2.	 The description of the property with respect to which the election is being made is as follows:

 an option to purchase [Number] shares (the “Shares”) of Common Stock, $0.0001 par value
per share, of Foghorn Therapeutics Inc., a Delaware corporation (the “Company”). 
  

	3.	 This election is made for the calendar year 2017, with respect to the transfer of the property to the Taxpayer
on                     , [Year]. 

  

	4.	 Description of restrictions: The property is subject to the following restrictions: 

In the event that the Taxpayer’s employment with the Company or an affiliate of the Company is terminated, the Company may repurchase all
or any portion of the Shares at the acquisition price paid by the Taxpayer. 
  

	5.	 The fair market value at time of transfer (determined without regard to any restrictions other than
restrictions which by their terms will never lapse) of the property with respect to which this election is being made was not more than $0.0001 per Share. 

  

	6.	 The amount paid by the Taxpayer for said property was $0.0001 per Share. 

 

	7.	 A copy of this statement has been furnished to the Company. 

Signed this      day of
                    , [Year]. 
  

					
	By:	 	  

			
		 	Name:	 	  

 EXHIBIT B 

CONSENT OF SPOUSE 
 I,
                    , spouse of
                    , acknowledge that I have read the Stock Restriction Agreement dated as of the      of
                     [Year] (the “Agreement”) to which this Consent is attached as Exhibit B and that I know
its contents. Capitalized terms used and not defined herein shall have the meanings assigned to such terms in the Agreement. I am aware that by its provisions the Shares granted to my spouse are subject to a Repurchase Right in favor of Foghorn
Therapeutics Inc. (the “Company”) and that, accordingly, the Company has the right to repurchase up to all of the Restricted Shares of which I may become possessed as a result of a gift from my spouse or a court decree and/or any
property settlement in any domestic litigation. 
 I hereby agree that my interest, if any, in the Restricted Shares subject to the
Agreement shall be irrevocably bound by the Agreement and further understand and agree that any community property interest I may have in the Restricted Shares shall be similarly bound by the Agreement. 

I agree to the Repurchase Right described in the Agreement and I hereby consent to the repurchase of the Restricted Shares by the Company and
the sale of the Restricted Shares by my spouse or my spouse’s legal representative in accordance with the provisions of the Agreement. Further, as part of the consideration for the Agreement, I agree that, at my death, if I have not disposed of
any interest of mine in the Restricted Shares by an outright bequest of the Restricted Shares to my spouse, then the Company shall have the same rights against my legal representative to exercise the Repurchase Right with respect to any interest of
mine in the Restricted Shares as the Company would have had pursuant to the Agreement if I had acquired the Restricted Shares pursuant to a court decree in domestic litigation. 

I AM AWARE THAT THE LEGAL, FINANCIAL AND RELATED MATTERS CONTAINED IN THE AGREEMENT ARE COMPLEX AND THAT I AM FREE TO SEEK INDEPENDENT
PROFESSIONAL GUIDANCE OR COUNSEL WITH RESPECT TO THIS CONSENT. I HAVE EITHER SOUGHT SUCH GUIDANCE OR COUNSEL OR DETERMINED AFTER REVIEWING THE AGREEMENT CAREFULLY THAT I WILL WAIVE SUCH RIGHT. 

Dated as of the      day of
                    , [Year]. 
  

			
	  

		
	Print name:

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