Document:

EX-10.1

 Exhibit 10.1 

SQZ Biotechnologies Company 

2014 Stock Incentive Plan 
  

	 	1.	 Purpose. 

The purpose of this plan (the “Plan”) is to secure for SQZ Biotechnologies Company., a Delaware corporation (the
“Company”) and its shareholders the benefits arising from capital stock ownership by employees, officers and directors of, and consultants or advisors to, the Company and its parent and subsidiary corporations who are
expected to contribute to the Company’s future growth and success. Under the Plan recipients may be awarded both (i) Options (as defined in Section 2.1) to purchase the Company’s common stock, par value $.001 (“Common
Stock”) and (ii) shares of Common Stock (“Restricted Stock Awards”). Except where the context otherwise requires, the term “Company” shall include any parent and all present and
future subsidiaries of the Company as defined in Sections 424(e) and 424(f) of the Internal Revenue Code of 1986, as amended or replaced from time to time (the “Code”). Those provisions of the Plan which make express
reference to Section 422 of the Code shall apply only to Incentive Stock Options (as that term is defined below). 
  

	 	2.	 Types of Awards and Administration. 

2.1 Options. Options granted pursuant to the Plan (“Options”) shall be authorized by action
of the Board of Directors of the Company (the “Board’’ or “Board of Directors”) and may be either incentive stock options (“Incentive Stock Options”) meeting the
requirements of Section 422 of the Code or non-statutory Options which are not intended to meet the requirements of Section 422. All Options when granted are intended to be non-statutory Options, unless the applicable Option Agreement (as defined in Section 5.1) explicitly states that the Option is intended to be an Incentive Stock Option. The vesting of Options may be conditioned
upon the completion of a specified period of employment with the Company and/or such other conditions or events as the Board may determine. The Board may also provide that Options are immediately exercisable subject to certain repurchase rights in
the Company dependent upon the continued employment of the optionee and/or such other conditions or events as the Board may determine. 

2.1.1 Incentive Stock Options. Incentive Stock Options may only be granted to employees of the Company. For so long as the Code
shall so provide, Options granted to any employee under the Plan (and any other incentive stock option plans of the Company) which are intended to constitute Incentive Stock Options shall not constitute Incentive Stock Options to the extent that
such Options, in the aggregate, become exercisable for the first time in any one calendar year for shares of Common Stock with an aggregate fair market value (determined as of the respective date or dates of grant) of more than $100,000. If an
Option is intended to be an Incentive Stock Option, and if for any reason such Option (or any portion thereof) shall not qualify as an Incentive Stock Option, then, to the extent of such nonqualification, such Option (or portion thereof) shall be
regarded as a non-statutory Option appropriately granted under the Plan provided that such Option (or portion thereof) otherwise meets the Plan’s requirements relating to non-statutory Options. 

 2.2 Restricted Stock Awards. The Board in its discretion may
grant Restricted Stock Awards, entitling the recipient to acquire, for a purchase price determined by the Board, shares of Common Stock subject to such restrictions and conditions as the Board may determine at the time of grant
(“Restricted Stock”), including continued employment and/or achievement of pre-established performance goals and objectives. 

2.3 Administration. The Plan shall be administered by the Board, whose construction and interpretation of the
terms and provisions of the Plan shall be final and conclusive. The Board may in its sole discretion authorize issuance of Restricted Stock, the grant of Options and the issuance of shares upon exercise of such Options as provided in the Plan. The
Board shall have authority, subject to the express provisions of the Plan, to construe Restricted Stock Agreements, Option Agreements and the Plan, to prescribe, amend and rescind rules and regulations relating to the Plan, to determine the terms
and provisions of Restricted Stock Agreements and Option Agreements, and to make all other determinations in the judgment of the Board necessary or desirable for the administration of the Plan. The Board may correct any defect or supply any omission
or reconcile any inconsistency in the Plan or in any Restricted Stock Agreement or Option Agreement 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. No
director or person acting pursuant to authority delegated by the Board shall be liable for any action or determination under the Plan made in good faith. The Board may, to the full extent permitted by or consistent with applicable laws or
regulations, delegate any or all of its powers under the Plan to a committee (the “Committee”) appointed by the Board, and if the Committee is so appointed, to the extent of such delegation, all references to the Board in the
Plan shall mean and relate to such Committee, other than references to the Board in this sentence and in Section 18 (as to amendment or termination of the Plan) and Section 22. 

 

	 	3.	 Eligibility. 

Options may be granted, and Restricted Stock may be issued, to persons who are, at the time of such grant or issuance, employees, officers or
directors of, or consultants or advisors to, the Company; provided that the class of persons to whom Incentive Stock Options may be granted shall be limited to employees of the Company.  

3.1 10% Shareholder. If any employee to whom an Incentive Stock Option is to be granted is, at the time of the
grant of such Option, the owner of stock possessing more than 10% of the total combined voting power of all classes of stock of the Company (after taking into account the attribution of stock ownership rules of Section 424(d) of the Code) (a
“Greater Than 10% Shareholder”), any Incentive Stock Option granted to such individual must: (i) have an exercise price per share of not less than 110% of the fair market value of one share of Common Stock at the time of
grant; and (ii) expire by its terms not more than five years from the date of grant. 

  
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	 	4.	 Stock Subject to Plan. 

Subject to adjustment as provided in Section 14.2 below, the maximum number of shares of Common Stock which may be issued under the Plan
is 3,859,080 shares, all of which may be issued with respect to Incentive Stock Options. If an Option shall expire or terminate for any reason without having been exercised in full, the unpurchased shares subject to such Option shall again be
available for subsequent Option grants or Restricted Stock Awards under the Plan. If shares of Restricted Stock shall be forfeited to, or otherwise repurchased by, the Company pursuant to a Restricted Stock Agreement, such repurchased shares shall
again be available for subsequent Option grants or Restricted Stock Awards under the Plan. If shares issued upon exercise of an Option are tendered to the Company in payment of the exercise price of an Option, such tendered shares shall again be
available for subsequent Option grants or Restricted Stock Awards under the Plan. 
  

	 	5.	 Forms of Restricted Stock Agreements and Option Agreements. 

5.1 Option Agreement. Each recipient of an Option shall execute an option agreement (“Option Agreement”)
in such form not inconsistent with the Plan as may be approved by the Board of Directors. Such Option Agreements may differ among recipients. 

5.2 Restricted Stock Agreement. Each recipient of a grant of Restricted Stock shall execute an agreement (“Restricted Stock
Agreement”) in such form not inconsistent with the Plan as may be approved by the Board of Directors. Such Restricted Stock Agreements may differ among recipients. 

5.3 “Lock-Up” Agreement. Unless the Board specifies otherwise,
each Restricted Stock Agreement and Option Agreement shall provide that upon the request of the Company or the managing underwriter(s) of any offering of securities of the Company that is the subject of a registration statement filed under the
United States Securities Act of 1933, as amended from time to time (the “Act”), the holder of any Option or the purchaser of any Restricted Stock shall, in connection therewith, agree in writing (in such form as the Company
or such managing underwriter(s) shall request) to the general effect that for a period of time (not to exceed 180 days, plus such additional number of days (not to exceed 35) as may reasonably be requested to enable the underwriter(s) of such
offering to comply with Rule 2711(f) of the Financial Industry Regulatory Authority or any amendment or successor thereto) from the effective date of the registration statement under the Act for such offering, the holder or purchaser will not sell,
make any short sale of, loan, grant any option for the purchase of, or otherwise dispose of any shares of the common stock of the Company owned or controlled by him or her. 
  

	 	6.	 Purchase Price. 

6.1 General. The purchase price per share of Restricted Stock and per share of stock deliverable upon the exercise of an Option
shall be determined by the Board, provided, however, that in the case of any Option, the exercise price shall not be less than 100% of the fair market value of such stock, as determined by the Board, at the time of grant of such Option, or less than
110% of such fair market value in the case of any Incentive Stock Option granted to a Greater Than 10% Shareholder. 

  
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 6.2 Payment of Purchase Price. Option Agreements may provide for the payment
of the exercise price by delivery of cash or a check to the order of the Company in an amount equal to the exercise price of such Options, or, to the extent provided in the applicable Option Agreement, by one of the following methods: 

                (i) with the consent of the
Board, by delivery to the Company of shares of Common Stock; such surrendered shares shall have a fair market value equal in amount to the exercise price of the Options being exercised, 

                (ii) with the consent of the
Board, a personal recourse note issued by the optionee to the Company in a principal amount equal to such aggregate exercise price and with such other terms, including interest rate and maturity, as the Company may determine in its discretion;
provided, however, that the interest rate borne by such note shall not be less than the lowest applicable federal rate, as defined in Section 1274(d) of the Code, 

                (iii) with the consent of the
Board, if the class of Common Stock is registered under the Securities Exchange Act of 1934 at such time, subject to rules as may be established by the Board, by delivery to the Company of a properly executed exercise notice along with irrevocable
instructions to a broker to promptly deliver to the Company cash or a check payable and acceptable to the Company for the purchase price, 

                (iv) with the consent of the
Board, by reducing the number of Option shares otherwise issuable to the optionee upon exercise of the Option by a number of shares of Common Stock having a fair market value equal to such aggregate exercise price, 

                (v) with the consent of the
Board, by any combination of such methods of payment. 
 The fair market value of any shares of Common Stock or other non-cash consideration which may be delivered upon exercise of an Option shall be determined by the Board of Directors. Restricted Stock Agreements may provide for the payment of any purchase price in any manner
approved by the Board of Directors at the time of authorizing the issuance thereof. 
  

	 	7.	 Option Period. 

Notwithstanding any other provision of the Plan or any Option Agreement, each Option and all rights thereunder shall expire on the date
specified in the applicable Option Agreement, provided that such date shall not be later than ten years after the date on which the Option is granted (or five years in the case of an Incentive Stock Option granted to a Greater Than 10% Shareholder),
and in either case, shall be subject to earlier termination as provided in the Plan or Option Agreement. 
  

	 	8.	 Exercise of Options. 

8.1 General. Each Option shall be exercisable either in full or in installments at such time or times and during such period as
shall be set forth in the Option Agreement evidencing such Option, subject to the provisions of the Plan. To the extent not exercised, installments shall accumulate and be exercisable, in whole or in part, at any time after becoming exercisable, but
not later than the date the Option expires. 

  
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 8.2 Notice of Exercise. An Option may be exercised by the optionee by
delivering to the Company on any business day a written notice specifying the number of shares of Common Stock the optionee then desires to purchase and specifying the address to which the certificates for such shares are to be mailed (the
“Notice”), accompanied by payment for such shares. In addition, the Company may require any individual to whom an Option is granted, as a condition of exercising such Option, to give written assurances (the
“Investment Letter”) in a substance and form satisfactory to the Company to the effect that such individual is acquiring the Common Stock subject to the Option for his or her own account for investment and not with a view to
the resale or distribution thereof, and to such other effects as the Company deems necessary or advisable in order to comply with any securities law(s). 

8.3 Delivery. As promptly as practicable after receipt of the Notice, the Investment Letter (if required) and payment, the
Company shall deliver or cause to be delivered to the optionee certificates for the number of shares with respect to which such Option has been so exercised, issued in the optionee’s name; provided, however, that such delivery shall be deemed
effected for all purposes when the Company or a stock transfer agent shall have deposited such certificates in the United States mail, addressed to the optionee, at the address specified in the Notice. 

 

	 	9.	 Transferability of Options. 

No Incentive Stock Option shall be assignable or transferable by the person to whom it is granted, either voluntarily or by operation of law,
except by will or the laws of descent and distribution, and during the life of an optionee, an Incentive Stock Option shall be exercisable only by the optionee. The Board may, in its discretion, determine the extent to which a non-statutory Option shall be transferable 
 9. Termination of Employment; Disability;
Death. Except as may be otherwise expressly provided in the terms and conditions of the Option Agreement, Options shall terminate on the earliest to occur of: 
  

	 	(i)	 the date of expiration thereof; 

 

	 	(ii)	 90 days after termination of the optionee’s employment with, or provision of services to, the Company by
the Company for Cause (as hereinafter defined); 

  

	 	(iii)	 90 days after the date of voluntary termination of the optionee’s employment with, or provision of
services to, the Company by the optionee (other than for death or permanent disability as defined below); or 

  

	 	(iv)	 90 days after the date of termination of the optionee’s employment with, or provision of services to, the
Company by the Company without Cause (other than for death or permanent disability as defined below). 

  
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 Until the date on which the Option so expires, the optionee may exercise that portion of his or her Option
which is exercisable at the time of termination of the employment or service relationship. 
 An employment or service relationship between
the Company and the optionee shall be deemed to exist during any period during which the optionee is employed by or providing services to the Company. Whether an authorized leave of absence or an absence due to military or government service shall
constitute termination of the employment relationship between the Company and the optionee shall be determined by the Board at the time thereof. 

For purposes of this Section 10, the term “Cause” shall mean (a) any material breach by the
optionee of any agreement to which the optionee and the Company are both parties, (b) any act (other than retirement) or omission to act by the optionee which may have a material and adverse effect on the Company’s business or on the
optionee’s ability to perform services for the Company, including, without limitation, the commission of any crime (other than minor traffic violations), or (c) any material misconduct or material neglect of duties by the optionee in
connection with the business or affairs of the Company. An optionee’s employment shall be deemed to have been terminated for Cause if the Company determines within thirty (30) days of the termination of employment (whether such termination
was voluntary or involuntary) that termination for Cause was warranted. 
 In the event of the permanent and total disability or death of an
optionee while in an employment or other relationship with the Company, any Option held by such optionee shall terminate on the earlier of the date of expiration of the Option or 180 days following the date of such disability or death. After
disability or death, the optionee (or in the case of death, his or her executor, administrator or any person or persons to whom this option may be transferred by will or by laws of descent and distribution) shall have the right, at any time prior to
such termination of an Option , to exercise the Option to the extent the optionee was entitled to exercise such Option as of the date of his or her disability or death. An optionee is permanently and totally disabled if he or she is unable to engage
in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to last for a continuous period of not less than 12 months; permanent and total disability shall be determined in
accordance with Section 22(e)(3) of the Code and the regulations issued thereunder. 
 10. Rights as a
Shareholder. The holder of an Option shall have no rights as a shareholder with respect to any shares covered by the Option (including, without limitation, any rights to receive dividends or
non-cash distributions with respect to such shares) until the date of issue of a stock certificate to him or her for such shares. No adjustment shall be made for dividends or other rights for which the record
date is prior to the date such stock certificate is issued. 
 11. Additional Provisions. The Board of
Directors may, in its sole discretion, include additional provisions in Restricted Stock Agreements and Option Agreements, including, without limitation, restrictions on transfer, rights of the Company to repurchase shares of Restricted Stock or
shares of Common Stock acquired upon exercise of Options, commitments to pay cash bonuses, to make, arrange for or guaranty loans or to transfer other property to optionees upon exercise of Options, or such other provisions as shall be determined by
the Board of Directors; provided that such additional provisions shall not be inconsistent with any other term or condition of the Plan and such additional provisions shall not be such as to cause any Incentive Stock Option to fail to qualify
as an Incentive Stock Option within the meaning of Section 422 of the Code. 

  
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 12. Acceleration, Extension, Etc. The Board of Directors may, in its
sole discretion, (i) accelerate the date or dates on which all or any particular Option or Options may be exercised or (ii) extend the period or periods oftime during which all, or any particular, Option or Options may be exercised. 

13. Adjustment Upon Changes in Capitalization 

13.1 No Effect of Options upon Certain Corporate Transactions. The existence of outstanding Options shall not affect in any way
the right or power of the Company to make or authorize any or all adjustments, recapitalizations, reorganizations or other changes in the Company’s capital structure or its business, or any merger or consolidation, or any issue of Common Stock,
or any issue of bonds, debentures, preferred or prior preference stock ahead of or affecting the Common Stock or the rights thereof, or the dissolution or liquidation of the Company, or any sale or transfer of all or any part of its assets or
business, or any other corporate act or proceeding, whether of a similar character or otherwise. 
 13.2 Adjustment
Provisions. If, through or as a result of any merger, consolidation, sale of all or substantially all of the assets of the Company, reorganization, recapitalization, reclassification, stock dividend, stock split, reverse stock split or other
similar transaction, (i) the outstanding shares of Common Stock are increased, decreased or exchanged for a different number or kind of shares or other securities of the Company, or (ii) additional shares or new or different shares or
other securities of the Company or other non-cash assets are distributed with respect to such shares of Common Stock or other securities, an appropriate and proportionate adjustment shall be made in
(x) the maximum number and kind of shares reserved for issuance under the Plan, (y) the number and kind of shares or other securities subject to any then outstanding Options, and (z) the price for each share or other security subject
to any then outstanding Options, so that upon exercise of such Options, in lieu of the shares of Common Stock for which such Options were then exercisable, the relevant optionee shall be entitled to receive, for the same aggregate consideration, the
same total number and kind of shares or other securities, cash or property that the owner of an equal number of outstanding shares of Common Stock immediately prior to the event requiring adjustment would own as a result of the event. If any such
event shall occur, appropriate adjustment shall also be made in the application of the provisions of this Section 14 and Section 15 with respect to Options and the rights of optionees after the event so that the provisions of such Sections
shall be applicable after the event and be as nearly equivalent as practicable in operation after the event as they were before the event. 

13.3 No Adjustment in Certain Cases. Except as hereinbefore expressly provided, the issue by the Company of shares of stock of
any class, or securities convertible into shares of stock of any class, for cash or property or for labor or services, either upon direct sale or upon the exercise of rights or warrants to subscribe therefor, or upon conversion of shares or
obligations ofthe Company convertible into such shares or other securities, shall not affect, and no adjustment by reason thereof shall be made with respect to, the number or price of shares of Common Stock then subject to outstanding options. 

  
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 13.4 Board Authority to Make Adjustments. Any adjustments under
this Section 14 will be made by the Board of Directors, whose determination as to what adjustments, if any, will be made and the extent thereof will be final, binding and conclusive. No fractional shares will be issued under the Plan on account
of any such adjustments. 
 14. Effect of Certain Transactions  

14.1 General. Except as provided in any Option Agreement or Restricted Stock Agreement to the contrary, if the
Company is merged with or into or consolidated with another corporation under circumstances where the stockholders of the Company immediately prior to such merger or consolidation do not own after such merger or consolidation shares representing at
least fifty percent (50%) ofthe voting power of the Company or the surviving or resulting corporation, as the case may be, or if shares representing fifty percent (50%) or more of the voting power of the Company are transferred to an Unrelated Third
Party, as hereinafter defined, or if the Company is liquidated, or sells or otherwise disposes of all or substantially all its assets (each such transaction is referred to herein as a “Change in Control Transaction”), the Board, or the
board of directors of any corporation assuming the obligations of the Company, may, in its discretion, take any one or more of the following actions, as to some or all outstanding Options or Restricted Stock Awards (and need not take the same action
as to each such Option or Restricted Stock Award): (i) provide that such Options shall be assumed, or equivalent Options shall be substituted, by the acquiring or succeeding corporation (or an affiliate thereof), provided that any such
Options substituted for Incentive Stock Options shall meet the requirements of Section 424(a) of the Code, (ii) upon written notice to the optionees, provide that all unexercised Options will terminate immediately prior to the consummation
of the Change in Control Transaction unless exercised by the optionee to the extent otherwise then exercisable within a specified period following the date of such notice, (iii) upon written notice to the grantees, provide that all unvested
shares of Restricted Stock shall be repurchased at cost, (iv) make or provide for a cash payment to the optionees equal to the difference between (A) the fair market value of the per share consideration (whether cash, securities or other
property or any combination of the above) the holder of a share of Common Stock will receive upon consummation of the Change in Control Transaction (the “Per Share Transaction Price”) times the number of shares
of Common Stock subject to outstanding vested Options (to the extent then exercisable at prices not equal to or in excess of the Per Share Transaction Price) and (B) the aggregate exercise price of such outstanding vested Options, in exchange
for the termination of such Options, or (v) provide that all or any outstanding Options shall become exercisable and all or any outstanding Restricted Stock A wards shall vest in part or in full immediately prior to such event. To the extent
that any Options are exercisable at a price equal to or in excess ofthe Per Share Transaction Price, the Board may provide that such Options shall terminate immediately upon the consummation of the Change in Control Transaction without any payment
being made to the holders of such Options. “Unrelated Third Party” shall mean any person who is not, on the date of adoption of this Plan by the Board, a holder of stock of any class or preference or any stock
option of the Company. 

  
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 14.2 Substitute Options. The Company may grant Options in substitution for
options held by employees, officers or directors of, or consultants or advisors to, another corporation who become employees, officers or directors of, or consultants or advisors to, the Company, as the result of a merger or consolidation of the
employing corporation with the Company or as a result of the acquisition by the Company of property or stock of the employing corporation. The Company may direct that substitute Options be granted on such terms and conditions as the Board considers
appropriate in the circumstances. 
 14.3 Restricted Stock. In the event of a business combination or other transaction of the
type detailed in Section 15.1, any securities, cash or other property received in exchange for shares of Restricted Stock shall continue to be governed by the provisions of any Restricted Stock Agreement pursuant to which they were issued,
including any provision regarding vesting, and such securities, cash, or other property may be held in escrow on such terms as the Board of Directors may direct, to insure compliance with the terms of any such Restricted Stock Agreement. 

15. No Special Employment Rights. Nothing contained in the Plan or in any Option Agreement or Restricted Stock Agreement
shall confer upon any optionee or holder of Restricted Stock any right with respect to the continuation of his or her employment by the Company or interfere in any way with the right of the Company at any time to terminate such employment or to
increase or decrease his or her compensation. 
 16. Other Employee Benefits. The amount of any compensation deemed to
be received by an employee as a result of the issuance of shares of Restricted Stock or the grant or exercise of an Option or the sale of shares received upon issuance of a Restricted Stock Award or exercise of an Option will not constitute
compensation with respect to which any other employee benefits of such employee are determined, including, without limitation, benefits under any bonus, pension, profit-sharing, life insurance or salary continuation plan, except as otherwise
specifically determined by the Board of Directors. 
 17. Amendment of the Plan. 

17.1 The Board may at any time, and from time to time, modify or amend in any respect or terminate the Plan. If shareholder approval is not
obtained within twelve months after any amendment increasing the number of shares authorized under the Plan or changing the class of persons eligible to receive Options under the Plan, no Options granted pursuant to such amendments shall be deemed
to be Incentive Stock Options and no Incentive Stock Options shall be issued pursuant to such amendments thereafter. 
 17.2 The termination
or any modification or amendment of the Plan shall not, without the consent of an optionee or the holder of Restricted Stock, adversely affect his or her rights under an Option or Restricted Stock Award previously granted to him or her. With the
consent of the recipient of Restricted Stock or optionee affected, the Board may amend outstanding Restricted Stock Agreements or Option Agreements in a manner not inconsistent with the Plan. 

  
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 18. Withholding. The Company shall have the right to
deduct from payments of any kind otherwise due to the optionee or recipient of Restricted Stock, any federal, state or local taxes of any kind required by law to be withheld with respect to issuance of any shares of Restricted Stock or shares issued
upon exercise of Options. Prior to delivery of any Common Stock pursuant to the terms of this Plan, the Board has the right to require that the optionee or recipient of Restricted Stock remit to the Company an amount sufficient to satisfy any
minimum tax withholding obligation. Subject to the prior approval of the Company, which may be withheld by the Company in its sole discretion, the obligor may elect to satisfy any minimum withholding obligations, in whole or in part, (i) by
causing the Company to withhold shares of Common Stock otherwise issuable, or (ii) by delivering to the Company a sufficient number of shares of Common Stock. The shares so withheld shall have a fair market value equal to such minimum
withholding obligation. The fair market value of the shares used to satisfy such minimum withholding obligation shall be determined by the Company as of the date that the amount of tax to be withheld is to be determined. A person who has made an
election pursuant to this Section 19 may only satisfy his or her withholding obligation with shares of Common Stock which are not subject to any repurchase, forfeiture, unfulfilled vesting or other similar restrictions. 

19. Effective Date and Duration of the Plan.  

19.1 Effective Date. The Plan shall become effective when adopted by the Board of Directors. If shareholder
approval is not obtained within twelve months after the date of the Board’s adoption of the Plan, no Options previously granted under the Plan shall be deemed to be Incentive Stock Options and no Incentive Stock Options shall be granted
thereafter. Amendments to the Plan not requiring shareholder approval shall become effective when adopted by the Board. Amendments requiring shareholder approval shall become effective when adopted by the Board, but if shareholder approval is not
obtained within twelve months of the Board’s adoption of such amendment, any Incentive Stock Options granted pursuant to such amendment shall be deemed to be non-statutory Options provided that such
Options are authorized by the Plan. Subject to this limitation, Options may be granted under the Plan at any time after the effective date and before the date fixed for termination of the Plan. 

19.2 Termination. Unless sooner terminated by action of the Board of Directors, the Plan shall terminate upon the
close of business on the day next preceding the tenth anniversary of the date of its adoption by the Board of Directors. 
 20.
Provision for Foreign Participants. The Board of Directors may, without amending the Plan, modify the terms of Option Agreements or Restricted Stock Agreements to differ from those specified in the Plan with respect to
participants who are foreign nationals or employed outside the United States to recognize differences in laws, rules, regulations or customs of such foreign jurisdictions with respect to tax, securities, currency, employee benefit or other matters.

  
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 21. Requirements of Law. The Company shall not be required to
sell or issue any shares under any Option or Restricted Stock Award if the issuance of such shares shall constitute a violation by the optionee, the Restricted Stock Award recipient, or by the Company of any provision of any law or regulation of any
governmental authority. In addition, in connection with the Act, the Company shall not be required to issue any shares upon exercise of any Option unless the Company has received evidence satisfactory to it to the effect that the holder of such
Option will not transfer such shares except pursuant to a registration statement in effect under the Act or unless an opinion of counsel satisfactory to the Company has been received by the Company to the effect that such registration is not
required in connection with any such transfer. Any determination in this connection by the Board shall be final, binding and conclusive. In the event the shares issuable on exercise of an Option are not registered under the Act or under the
securities laws of each relevant state or other jurisdiction, the Company may imprint on the certificate(s) appropriate legends that counsel for the Company considers necessary or advisable to comply with the Act or any such state or other
securities law. The Company may register, but in no event shall be obligated to register, any securities covered by the Plan pursuant to the Act; and in the event any shares are so registered the Company may remove any legend on certificates
representing such shares. The Company shall not be obligated to take any affirmative action in order to cause the exercise of an Option, the grant of any Restricted Stock Award or the issuance of shares pursuant thereto to comply with any law or
regulation of any governmental authority. 
 22. Conversion of Incentive Stock Options into
Non-Qualified Options; Termination. The Board of Directors, with the consent of any optionee, may in its discretion take such actions as may be necessary to convert such optionee’s
Incentive Stock Options (or any installments or portions of installments thereof) that have not been exercised on the date of conversion into non-statutory Options at any time prior to the expiration of such
Incentive Stock Options, regardless of whether the optionee is an employee of the Company or a parent or subsidiary of the Company at the time of such conversion. At the time of such conversion, the Board of Directors (with the consent of the
optionee) may impose such conditions on the exercise of the resulting non-statutory Options as the Board of Directors in its discretion may determine, provided that such conditions shall not be inconsistent
with this Plan. Nothing in this Plan shall be deemed to give any optionee the right to have such optionee’s Incentive Stock Options converted into non-statutory Options, and no such conversion shall occur
until and unless the Board of Directors takes appropriate action. The Board of Directors, with the consent of the optionee, may also terminate any portion of any Incentive Stock Option that has not been exercised at the time of such termination.

 23. Non-Exclusivity of this Plan;
Non-Uniform Determinations. Neither the adoption of this Plan by the Board of Directors nor the approval of this Plan by the stockholders of the Company shall be construed as creating any
limitations on the power of the Board of Directors to adopt such other incentive arrangements as it may deem desirable, including, without limitation, the granting of stock options otherwise than under this Plan, and such arrangements may be either
applicable generally or only in specific cases. 
 The determinations of the Board of Directors under this Plan need not be uniform and may
be made by it selectively among persons who receive or are eligible to receive Options or Restricted Stock Awards under this Plan (whether or not such persons are similarly situated). Without limiting the generality of the foregoing, the Board of
Directors shall be entitled, among 

  
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other things, to make non-uniform and selective determinations, and to enter into non-uniform and selective Option
Agreements and Restricted Stock Agreements, as to (a) the persons to receive Options or Restricted Stock Awards under this Plan, (b) the terms and provisions of Options or Restricted Stock Awards, (c) the exercise by the Board of
Directors of its discretion in respect of the exercise of Options pursuant to the terms of this Plan, and (d) the treatment of leaves of absence pursuant to Section 10 hereof. 

24. Governing Law. This Plan and each Option or Restricted Stock Award shall be governed by the laws of The Commonwealth of
Massachusetts, without regard to its principles of conflicts of law. 

  
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 APPENDIX A 

TO SQZ BIOTECHNOLOGIES COMPANY 2014 STOCK INCENTIVE PLAN 

FOR CALIFORNIA RESIDENTS ONLY 

This Appendix to the SQZ Biotechnologies Company 2014 Stock Incentive Plan (the “Plan”) shall have application only to participants
in the Plan who are residents of the State of California. Capitalized terms contained herein shall have the same meanings given to them in the Plan, unless otherwise provided in this Appendix. Notwithstanding any provision contained in the Plan
to the contrary and to the extent required by applicable law, the following terms and conditions shall apply to all Options and Restricted Stock Awards (collectively “Awards”) granted to residents of the State of California, until such
time as the Common Stock becomes subject to registration under the Securities Act of 1933:  
 1. Awards shall be nontransferable other
than by will or the laws of descent and distribution. Notwithstanding the foregoing, and to the extent permitted by Section 422 of the Code, the Board, in its discretion, may permit distribution of an Award to an inter vivos or testamentary
trust in which the Award is to be passed to beneficiaries upon the death of the trustor (settlor), or by gift to “immediate family” as that term is defined in Rule 16a-1 (e) of the United States
Exchange Act of 1934. 
 2. Unless employment is terminated for Cause, the right to exercise an Option in the event of termination of
employment, to the extent that the optionee is otherwise entitled to exercise an Option on the date employment terminates, shall be 
 (a)
at least six months from the date of termination of employment if termination was caused by death or permanent disability; and 
 (b) at
least 30 days from the date of termination if termination of employment was caused by other than death or permanent disability; 
 (c) but
in no event later than the remaining term of the Option. 
 3. Any Award exercised before shareholder approval is obtained shall be
rescinded if shareholder approval is not obtained within 12 months of the Board’s adoption of the Plan. 

 SQZ Biotechnologies Company (the “Company”)

 STOCK OPTION AGREEMENT 

The Option described in this Stock Option Agreement (the “Option Agreement”) was granted by the Company on the date of
grant set forth below (the “Date of Grant”) pursuant to the Company’s 2014 Stock Incentive Plan, as amended from time to time (the “Plan”), which is incorporated herein by reference and made a
part hereof. The holder of this Option (the “Holder”) hereby accepts this Option subject to all the terms and provisions of the Plan and this Option Agreement and agrees that (a) in the event of any conflict between the
terms hereof and those of the Plan, the terms of the Plan shall prevail, and (b) all decisions under and interpretations of the Plan by the Board of Directors of the Company (the “Board”) or of a committee that the Board
appoints (the “Committee”) shall be final, binding and conclusive upon the Holder and his or her heirs and legal representatives. 
  

	1.	 Name of Holder:  

 

	2.	 Date of Grant:1 

 

	3.	 Vesting Commencement Date:  

 

	4.	 Maximum number of shares for  

	    	 which this Option is exercisable: 

 

	5.	 Exercise (purchase) price per share:  

 

	6.	 Type of Option: [Incentive Stock Option/Non-statutory Stock
Option] 

  

	7.	 Expiration Date of Option (the “Expiration Date”):2  

  

	8.	 Vesting Schedule: [Vesting schedule to be specified in individual Option Agreements.]

 Notwithstanding the foregoing, all vesting shall cease upon the date the Holder is no longer a Service
Provider and the Option will immediately terminate and be forfeited as to any portion that is not vested as of such date. For purposes of this Option Agreement, “Service Provider” means an employee, advisor, director or consultant of the
Company or one of its subsidiaries. 
  

	9.	 Method of Exercise: This Option may be exercised by the delivery to the Company of written notice in a
form acceptable to the Company setting forth the number of shares of Common Stock, par value $0.001 per share (the “Common Stock”), of the Company (the “Shares”) with respect to which the Option is to
be exercised, together with payment by one of the following methods: 

 cash or a personal, certified or bank check or
postal money order payable to the order of the Company for an amount equal to the exercise price for the number of Shares being purchased; or 

 

	1 	 The Date of Grant should be the date that the Board approves the option. 

	2 	 The Expiration Date should be the day prior to the 10th
anniversary of the Date of Grant. 

 with the consent of the Company, any of the other methods set forth in the
Plan. 
 As an additional condition to exercise of this Option, the Holder shall deliver to the Company an investment letter
in form and substance satisfactory to the Company. No such investment letter shall be required as a condition to such exercise at any time when there shall be an effective registration statement under the Securities Act of 1933, as amended (the
“Act”) covering the Shares for which this Option may be exercised. 
 If required by the Company, the
Holder shall, as a condition precedent to exercising this Option, become a party to (i) the Voting Agreement, dated as of June 15, 2015, by and among the Company and the parties thereto, as may be amended and/or restated from time to time,
and (ii) the Right of First Refusal and Co-Sale Agreement, dated as of June 15, 2015, by and among the Company and the parties thereto, as may be amended and/or restated from time to time, and shall
execute and deliver to the Company a joinder to such agreements in a form acceptable to the Company. 
  

	10.	 Termination of Option. This Option may not be exercised to any extent after, and shall terminate on, the
earliest to occur of: 

  

	 	(i)	 the Expiration Date; 

 

	 	(ii)	 immediately upon the Holder’s termination as a Service Provider for Cause (as defined in the Plan);

  

	 	(iii)	 90 days after the Holder ceases to be a Service Provider for any reason other than Cause or due to death or
“permanent and total disability” (within the meaning of the Plan); or 

  

	 	(iv)	 180 days after the Holder ceases to be a Service Provider due to the Holder’s “permanent and total
disability” or death. 

 Holder acknowledges that an Incentive Stock Option exercised more than three months after
Holder’s termination of status as an employee of the Company, other than by reason of death or “permanent and total disability,” will be taxed as a non-statutory Stock Option. 

 

	11.	 Company’s Right of First Refusal. Any Shares issued pursuant to exercise of this Option shall be
subject to the Company’s right of first refusal as set forth at Appendix A. 

  

	12.	 Lock-Up Agreement. The Holder agrees that upon the request of
the Company or the managing underwriter(s) of any offering of securities of the Company that is the subject of a registration statement filed under the Act, for a period of time (not to exceed 180 days, plus such additional number of days (not to
exceed 35) as may reasonably be 

  
 2 

	 	
requested to enable the underwriter(s) of such offering to comply with Rule 2711(f) of the Financial Industry Regulatory Authority or any amendment or successor thereto) from the effective date
of the registration statement under the Act for such offering, the Holder will not sell, make any short sale of, loan, grant any option for the purchase of, or otherwise dispose of any Shares issued pursuant to the exercise of this Option, without
the prior written consent of the Company and such underwriters. The Holder further agrees to execute such agreements as may be reasonably requested by the underwriters that are consistent with this Section 12 or that are necessary to give
further effect hereto. 

  

	13.	 Tax Withholding. The Company’s obligation to deliver Shares shall be subject to the Holder’s
satisfaction of any federal, state and local income and employment tax withholding requirements arising in connection with the Option. 

  

	14.	 Special Tax Consequences. If this Option is designated as an Incentive Stock Option:

  

	 	(i)	 The Holder acknowledges that to the extent the aggregate fair market value of shares (determined as of the time
the option with respect to the shares is granted) with respect to which stock options intended to qualify as “incentive stock options” under Section 422 of the Internal Revenue Code of 1986, as amended (the
“Code”), including the Option, are exercisable for the first time by the Holder during any calendar year exceeds $100,000 or if for any other reason such stock options do not qualify or cease to qualify for treatment as
“incentive stock options” under Section 422 of the Code, such stock options (including this Option) will be treated as non-qualified stock options. The Holder further acknowledges that the rule
set forth in the preceding sentence will be applied by taking this Option and other stock options into account in the order in which they were granted, as determined under Section 422(d) of the Code. 

 

	 	(ii)	 The Holder will give prompt written notice to the Company of any disposition or other transfer of any Shares
acquired under this Option Agreement if such disposition or other transfer is made (a) within two (2) years from the Date of Grant or (b) within one (1) year after the transfer of such Shares to the Holder. Such notice will
specify the date of such disposition or other transfer and the amount realized, in cash, other property, assumption of indebtedness or other consideration, by the Holder in such disposition or other transfer. 

 

	15.	 Notice. Any notice to be given to the Company hereunder shall be deemed sufficient if addressed to the
Company and delivered to the office of the Company, SQZ Biotechnologies Company, 100 Morrissey Blvd, Venture Development Center, Boston, MA 02125, attention of the Chief Executive Officer, or such other address as the Company may hereafter
designate. 

  
 3 

 Any notice to be given to the Holder hereunder shall be deemed sufficient if addressed to
and delivered in person to the Holder at his or her address furnished to the Company or when deposited in the mail, postage prepaid, addressed to the Holder at such address. 

[signature page follows] 

  
 4 

 IN WITNESS WHEREOF, the parties have executed this Option Agreement, or caused this Option
Agreement to be executed, as of the Date of Grant. 
  

			
	SQZ Biotechnologies Company

 
			
		
	By:	 	 

 
			
	Name:	 	Armon Sharei, Ph.D.

 
			
	Title:	 	Chief Executive Officer

 The undersigned Holder hereby acknowledges receipt of a copy of the Plan and this Option Agreement (including Appendix A
hereto), and agrees to the terms of the Option, this Option Agreement and the Plan. 

	
	
	   

	Name:

  
 5 

 APPENDIX A 

Right of First Refusal 

1. General. Prior to the effective date of a registration statement under the Act covering any shares of the
Company’s Common Stock and until such time as the Company shall have effected a public offering of its Common Stock registered under the Act, in the event that, at any time when the Holder (which term for purposes of this Appendix A shall mean
the Holder and his or her executors, administrators and any other person to whom this Option may be transferred by will or the laws of descent and distribution) is permitted to do so, the Holder desires to sell, assign or otherwise transfer any of
the Shares issued upon the exercise of this Option, the Holder shall first offer such Shares to the Company by giving written notice of the Holder’s desire so to sell, assign or transfer such Shares. 

2. Notice of Intended Transfer. The notice shall state the number of Shares offered, the name of the person or
persons to whom it is proposed to sell, assign or transfer such Shares and the price at which such Shares are intended to be sold, assigned or transferred. Such notice shall constitute an offer to the Company for the Company to purchase the number
of Shares set forth in the notice at a price per share equal to the price stated therein. 
 3. Company to Accept or Decline
Within 30 Days. The Company may accept the offer as to all, but not less than all, such Shares by notifying the Holder in writing within 30 days after receipt of such notice of its acceptance of the offer. If the offer is accepted,
the Company shall have 60 days after such acceptance within which to purchase the offered Shares at a price per share as aforesaid. Upon the closing of such purchase, the Holder shall transfer to the Company the Shares offered in the notice, free of
all liens, encumbrances and rights of others, and shall deliver any certificate(s) representing such Shares, as well as the duly executed stock powers accompanying such certificate(s), to the Company. If within the applicable time periods the Holder
does not receive notice of the Company’s intention to purchase the offered Shares, or if payment in full of the purchase price is not made by the Company, the offer shall be deemed to have been rejected and the Holder may transfer title to such
Shares within 90 days from the date of the Holder’s written notice to the Company of the Holder’s intention to sell, but such transfer shall be made only to the proposed transferee and at the proposed price as stated in such notice and
after compliance with any other provisions of this Option applicable to the transfer of such Shares. 
 4. Transferred Shares
to Remain Subject to Rights of the Company. Shares that are so transferred to such transferee shall remain subject to the provisions of the Plan and the Option Agreement, including the rights of the Company set forth in this Appendix
A, and any other applicable agreements governing the Shares that are transferred. As a condition to such transfer, such transferee shall execute and deliver all such documents as the Company may require to evidence the binding agreement of such
transferee so to remain subject to the rights of the Company. 

  
 6 

 5. Remedies of Company. No sale, assignment, pledge or other
transfer of any of the Shares covered by this Option shall be effective or given effect on the books of the Company unless all of the applicable provisions of this Appendix A have been duly complied with, and the Company may inscribe on the face of
any certificate representing any of such Shares a legend referring to the provisions of this Appendix A. If any transfer of Shares is made or attempted in violation of the foregoing restrictions, or if Shares are not offered to the Company as
required hereby, the Company shall have the right to purchase such Shares from the owner thereof or his transferee at any time before or after the transfer, as herein provided. In addition to any other legal or equitable remedies which it may have,
the Company may enforce its rights by actions for specific performance (to the extent permitted by law) and may refuse to recognize any transferee as one of its stockholders for any purpose, including, without limitation, for purposes of dividend
and voting rights, until all applicable provisions hereof have been complied with. 
 6. Shares Subject to Right of First
Refusal. For purposes of the Company’s right of first refusal pursuant to this Appendix A, the term “Shares” shall include any and all new, substituted or additional securities or other property issued to the Holder, by
reason of his or her ownership of Common Stock pursuant to the exercise of this Option, in connection with any stock dividend, liquidating dividend, stock split or other change in the character or amount of any of the outstanding securities of the
Company, or any consolidation, merger or sale of all or substantially all of the assets of the Company. 
 7. Legends on Stock
Certificates. Any certificate representing Shares subject to the provisions of this Appendix A may have endorsed thereon one or more legends, substantially as follows: 

 

	 	(i)	 “Any disposition of any interest in the securities represented by this certificate is subject to
restrictions, and the securities represented by this certificate are subject to certain options, contained in a certain agreement between the record holder hereof and the Company, a copy of which will be mailed to any holder of this certificate
without charge upon receipt by the Company of a written request therefor.” 

  

	 	(ii)	 “The shares of stock represented by this certificate have not been registered under the Securities Act of
1933 (the “Act”) or under the securities laws of any state and may not be pledged, hypothecated, sold or otherwise transferred unless such shares have been registered under the Act or unless the Company has received an opinion of counsel
satisfactory to the Company, in form and substance satisfactory to the Company, that such registration is not required.” 

8. Right of First Refusal to Lapse Upon Registration. The restrictions imposed by this Appendix A shall terminate
in all respects upon the effective date of a registration statement under the Act covering any of the Company’s Common Stock. 
 * * * *
* 

  
 7 

 
SQZ BIOTECHNOLOGIES COMPANY 

2020 INCENTIVE AWARD PLAN 

RESTRICTED STOCK GRANT NOTICE 

Capitalized terms not specifically defined in this Restricted Stock Grant Notice (the “Grant Notice”) have the
meanings given to them in the 2020 Incentive Award Plan (as amended from time to time, the “Plan”) of SQZ Biotechnologies Company (the “Company”). 

The Company has granted to the participant listed below (“Participant”) the shares of Restricted Stock
described in this Grant Notice (the “Restricted Shares”), subject to the terms and conditions of the Plan and the Restricted Stock Agreement attached as Exhibit A (the “Agreement”), both of
which are incorporated into this Grant Notice by reference. 
  

	
	Participant:
	
	Grant Date:
	
	Number of Restricted Shares:
	
	Vesting Commencement Date:
	
	Vesting Schedule:

 By Participant’s signature below, Participant agrees to be bound by the terms of this Grant Notice, the
Plan and the Agreement. Participant has reviewed the Plan, this Grant Notice and the Agreement in their entirety, has had an opportunity to obtain the advice of counsel prior to executing this Grant Notice and fully understands all provisions of the
Plan, this Grant Notice and the Agreement. Participant hereby agrees to accept as binding, conclusive and final all decisions or interpretations of the Administrator upon any questions arising under the Plan, this Grant Notice or the Agreement. 

 

							
	SQZ BIOTECHNOLOGIES COMPANY	 		  	PARTICIPANT
				
	By:	 	
                     
            
	 	                    	  	  

	Name:	 	  
	 		  	
	Title:	 	  
	 		  	

 Exhibit A 

RESTRICTED STOCK AGREEMENT 

Capitalized terms not specifically defined in this Agreement have the meanings specified in the Grant Notice or, if not defined in the Grant
Notice, in the Plan. 
 ARTICLE I. 

GENERAL 
 1.1 Issuance
of Restricted Shares. The Company will issue the Restricted Shares to the Participant effective as of the grant date set forth in the Grant Notice and will cause (a) a stock certificate or certificates representing the Restricted Shares to
be registered in Participant’s name or (b) the Restricted Shares to be held in book-entry form. If a stock certificate is issued, the certificate will be delivered to, and held in accordance with this Agreement by, the Company or its
authorized representatives and will bear the restrictive legends required by this Agreement. If the Restricted Shares are held in book-entry form, then the book-entry will indicate that the Restricted Shares are subject to the restrictions of this
Agreement. 
 1.2 Incorporation of Terms of Plan. The Restricted Shares are subject to the terms and conditions set forth in this
Agreement and the Plan, which is incorporated herein by reference. In the event of any inconsistency between the Plan and this Agreement, the terms of the Plan will control. 

ARTICLE II. 
 VESTING,
FORFEITURE AND ESCROW 
 2.1 Vesting. The Restricted Shares will become vested Shares (the “Vested
Shares”) according to the vesting schedule in the Grant Notice except that any fraction of a Share that would otherwise become a Vested Share will be accumulated and will become a Vested Share only when a whole Vested Share has
accumulated. 
 2.2 Forfeiture. In the event of Participant’s Termination of Service for any reason, Participant will
immediately and automatically forfeit to the Company any Shares that are not Vested Shares (the “Unvested Shares”) at the time of Participant’s Termination of Service, except as otherwise determined by the Administrator
or provided in a binding written agreement between Participant and the Company. Upon forfeiture of Unvested Shares, the Company will become the legal and beneficial owner of the Unvested Shares and all related interests and Participant will have no
further rights with respect to the Unvested Shares. 
 2.3 Escrow. 

(a) Unvested Shares will be held by the Company or its authorized representatives until (i) they are forfeited, (ii) they become
Vested Shares or (iii) this Agreement is no longer in effect. By accepting this Award, Participant appoints the Company and its authorized representatives as Participant’s
attorney(s)-in-fact to take all actions necessary to effect any transfer of forfeited Unvested Shares (and Retained Distributions (as defined below), if any, paid on
such forfeited Unvested Shares) to the Company as may be required pursuant to the Plan or this Agreement and to execute such representations or other documents or assurances as the Company or such representatives deem necessary or advisable in
connection with any such transfer. The Company, or its authorized representative, will not be liable for any good faith act or omission with respect to the holding in escrow or transfer of the Restricted Shares. 

 (b) All cash dividends and other distributions made or declared with respect to Unvested
Shares (“Retained Distributions”) will be held by the Company until the time (if ever) when the Unvested Shares to which such Retained Distributions relate become Vested Shares. The Company will establish a separate Retained
Distribution bookkeeping account (“Retained Distribution Account”) for each Unvested Share with respect to which Retained Distributions have been made or declared in cash and credit the Retained Distribution Account (without
interest) on the date of payment with the amount of such cash made or declared with respect to the Unvested Share. Retained Distributions (including any Retained Distribution Account balance) will immediately and automatically be forfeited upon
forfeiture of the Unvested Share with respect to which the Retained Distributions were paid or declared. 
 (c) As soon as reasonably
practicable following the date on which an Unvested Share becomes a Vested Share, the Company will (i) cause the certificate (or a new certificate without the legend required by this Agreement, if Participant so requests) representing the Share
to be delivered to Participant or, if the Share is held in book-entry form, cause the notations indicating the Share is subject to the restrictions of this Agreement to be removed and (ii) pay to Participant the Retained Distributions relating
to the Share. 
 2.4 Rights as Stockholder. Except as otherwise provided in this Agreement or the Plan, upon issuance of the
Restricted Shares by the Company, Participant will have all the rights of a stockholder with respect to the Restricted Shares, including the right to vote the Restricted Shares and to receive dividends or other distributions paid or made with
respect to the Restricted Shares. 
 ARTICLE III. 

TAXATION AND TAX WITHHOLDING 

3.1 Representation. Participant represents to the Company that Participant has reviewed with Participant’s own tax advisors the
tax consequences of the Restricted Shares and the transactions contemplated by the Grant Notice and this Agreement. Participant is relying solely on such advisors and not on any statements or representations of the Company or any of its agents. 

3.2 Section 83(b) Election. If Participant makes an election under Section 83(b) of the Code with respect to
the Restricted Shares, Participant will deliver a copy of the election to the Company promptly after filing the election with the Internal Revenue Service. 

3.3 Tax Withholding. 
 (a)
The Company has the right and option, but not the obligation, to treat Participant’s failure to provide timely payment in accordance with the Plan of any withholding tax arising in connection with the Restricted Shares as Participant’s
election to satisfy all or any portion of the withholding tax by requesting the Company retain Shares otherwise deliverable under the Award. 

(b) Participant acknowledges that Participant is ultimately liable and responsible for all taxes owed in connection with the Restricted
Shares, regardless of any action the Company or any Subsidiary takes with respect to any tax withholding obligations that arise in connection with the Restricted Shares. Neither the Company nor any Subsidiary makes any representation or undertaking
regarding the treatment of any tax withholding in connection with the awarding, vesting or payment of the Restricted Shares or the subsequent sale of the Restricted Shares. The Company and the Subsidiaries do not commit and are under no obligation
to structure this Award to reduce or eliminate Participant’s tax liability. 

  
 A-2 

 ARTICLE IV. 

RESTRICTIVE LEGENDS AND TRANSFERABILITY 

4.1 Legends. Any certificate representing a Restricted Share will bear the following legend until the Restricted Share becomes a Vested
Share: 
 THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO FORFEITURE IN FAVOR OF THE COMPANY AND MAY BE TRANSFERRED ONLY IN
ACCORDANCE WITH THE TERMS OF A RESTRICTED STOCK AGREEMENT BETWEEN THE COMPANY AND THE STOCKHOLDER, A COPY OF WHICH IS ON FILE WITH THE SECRETARY OF THE COMPANY. 

4.2 Transferability. The Restricted Shares and any Retained Distributions are subject to the restrictions on transfer in the Plan and
may not be sold, assigned or transferred in any manner unless and until they become Vested Shares. Any attempted transfer or disposition of Unvested Shares or related Retained Distributions prior to the time the Unvested Shares become Vested Shares
will be null and void. The Company will not be required to (a) transfer on its books any Restricted Share that has been sold or otherwise transferred in violation of this Agreement or (b) treat as owner of such Restricted Share or accord
the right to vote or pay dividends to any purchaser or other transferee to whom such Restricted Share has been so transferred. The Company may issue appropriate “stop transfer” instructions to its transfer agent, if any, or make
appropriate notations to the same effect in its records. 
 ARTICLE V. 

OTHER PROVISIONS 
 5.1
Adjustments. Participant acknowledges that the Restricted Shares are subject to adjustment, modification and termination in certain events as provided in this Agreement and the Plan. 

5.2 Notices. Any notice to be given under the terms of this Agreement to the Company must be in writing and addressed to the Company in
care of the Company’s Secretary at the Company’s principal office or the Secretary’s then-current email address or facsimile number. Any notice to be given under the terms of this Agreement to Participant must be in writing and
addressed to Participant at Participant’s last known mailing address, email address or facsimile number in the Company’s personnel files. By a notice given pursuant to this Section, either party may designate a different address for
notices to be given to that party. Any notice will be deemed duly given when actually received, when sent by email, when sent by certified mail (return receipt requested) and deposited with postage prepaid in a post office or branch post office
regularly maintained by the United States Postal Service, when delivered by a nationally recognized express shipping company or upon receipt of a facsimile transmission confirmation. 

5.3 Titles. Titles are provided herein for convenience only and are not to serve as a basis for interpretation or construction of this
Agreement. 
 5.4 Conformity to Securities Laws. Participant acknowledges that the Plan, the Grant Notice and this Agreement are
intended to conform to the extent necessary with all Applicable Laws and, to the extent Applicable Laws permit, will be deemed amended as necessary to conform to Applicable Laws. 

5.5 Successors and Assigns. The Company may assign any of its rights under this Agreement to single or multiple assignees, and this
Agreement will inure to the benefit of the successors and assigns of the Company. Subject to the restrictions on transfer set forth in this Agreement or the Plan, this Agreement will be binding upon and inure to the benefit of the heirs, legatees,
legal representatives, successors and assigns of the parties hereto. 

  
 A-3 

 5.6 Limitations Applicable to Section 16 Persons. Notwithstanding
any other provision of the Plan or this Agreement, if Participant is subject to Section 16 of the Exchange Act, the Plan, the Grant Notice, this Agreement and the Restricted Shares will be subject to any additional limitations set forth in any
applicable exemptive rule under Section 16 of the Exchange Act (including any amendment to Rule 16b-3) that are requirements for the application of such exemptive rule. To the extent Applicable Laws
permit, this Agreement will be deemed amended as necessary to conform to such applicable exemptive rule. 
 5.7 Entire Agreement. The
Plan, the Grant Notice and this Agreement (including any exhibit hereto) constitute the entire agreement of the parties and supersede in their entirety all prior undertakings and agreements of the Company and Participant with respect to the
subject matter hereof. 
 5.8 Agreement Severable. In the event that any provision of the Grant Notice or this Agreement is held
illegal or invalid, the provision will be severable from, and the illegality or invalidity of the provision will not be construed to have any effect on, the remaining provisions of the Grant Notice or this Agreement. 

5.9 Limitation on Participant’s Rights. Participation in the Plan confers no rights or interests other than as herein provided.
This Agreement creates only a contractual obligation on the part of the Company as to amounts payable and may not be construed as creating a trust. Neither the Plan nor any underlying program, in and of itself, has any assets. Participant will have
only the rights of a general unsecured creditor of the Company with respect to amounts credited and benefits payable, if any, with respect to the Award. 

5.10 Not a Contract of Employment. Nothing in the Plan, the Grant Notice or this Agreement confers upon Participant any right to
continue in the employ or service of the Company or any Subsidiary or interferes with or restricts in any way the rights of the Company and its Subsidiaries, which rights are hereby expressly reserved, to discharge or terminate the services of
Participant at any time for any reason whatsoever, with or without cause, except to the extent expressly provided otherwise in a written agreement between the Company or a Subsidiary and Participant. 

5.11 Counterparts. The Grant Notice may be executed in one or more counterparts, including by way of any electronic signature, subject
to Applicable Law, each of which will be deemed an original and all of which together will constitute one instrument. 

* * * * * 

  
 A-4EX-10.2

 Exhibit 10.2 

SQZ BIOTECHNOLOGIES COMPANY 

2020 INCENTIVE AWARD PLAN 

ARTICLE I. 
 PURPOSE

 The Plan’s purpose is to enhance the Company’s ability to attract, retain and motivate persons who make (or are expected to
make) important contributions to the Company by providing these individuals with equity ownership opportunities. Capitalized terms used in the Plan are defined in Article XI. 

ARTICLE II. 
 ELIGIBILITY

 Service Providers are eligible to be granted Awards under the Plan, subject to the limitations described herein. 

ARTICLE III. 

ADMINISTRATION AND DELEGATION 

3.1 Administration. The Plan is administered by the Administrator. The Administrator has authority to determine which Service Providers
receive Awards, grant Awards and set Award terms and conditions, subject to the conditions and limitations in the Plan. The Administrator also has the authority to take all actions and make all determinations under the Plan, to interpret the Plan
and Award Agreements and to adopt, amend and repeal Plan administrative rules, guidelines and practices as it deems advisable. The Administrator may correct defects and ambiguities, supply omissions and reconcile inconsistencies in the Plan or any
Award as it deems necessary or appropriate to administer the Plan and any Awards. The Administrator’s determinations under the Plan are in its sole discretion and will be final and binding on all persons having or claiming any interest in the
Plan or any Award. 
 3.2 Appointment of Committees. To the extent Applicable Laws permit, the Board may delegate any or all of its
powers under the Plan to one or more Committees or officers of the Company or any of its Subsidiaries. The Board may abolish any Committee or re-vest in itself any previously delegated authority at any time.

 ARTICLE IV. 
 STOCK
AVAILABLE FOR AWARDS 
 4.1 Number of Shares. Subject to adjustment under Article VIII and the terms of this
Article IV, Awards may be made under the Plan covering up to the Overall Share Limit. As of the Plan’s effective date under Section 10.3, the Company will cease granting awards under the Prior Plans; however, Prior Plan Awards will
remain subject to the terms of the applicable Prior Plan. Shares issued under the Plan may consist of authorized but unissued Shares, Shares purchased on the open market or treasury Shares. 

4.2 Share Recycling. If all or any part of an Award or Prior Plan Award expires, lapses or is terminated, exchanged for cash,
surrendered, repurchased, canceled without having been fully exercised or forfeited, in any case, in a manner that results in the Company acquiring Shares covered by the Award or Prior Plan Award at a price not greater than the price (as adjusted to
reflect any Equity Restructuring) paid by the Participant for such Shares or not issuing any Shares covered by the Award or Prior Plan 

 
Award, the unused Shares covered by the Award or Prior Plan Award will, as applicable, become or again be available for Award grants under the Plan. Further, Shares delivered (either by actual
delivery or attestation) to the Company by a Participant to satisfy the applicable exercise or purchase price of an Award or Prior Plan Award and/or to satisfy any applicable tax withholding obligation (including Shares retained by the Company from
the Award or Prior Plan Award being exercised or purchased and/or creating the tax obligation) will, as applicable, become or again be available for Award grants under the Plan. The payment of Dividend Equivalents in cash in conjunction with any
outstanding Awards or Prior Plan Awards shall not count against the Overall Share Limit.     
 4.3 Incentive Stock
Option Limitations. Notwithstanding anything to the contrary herein, no more than 18,930,000 Shares may be issued pursuant to the exercise of Incentive Stock Options. 

4.4 Substitute Awards. In connection with an entity’s merger or consolidation with the Company or the Company’s acquisition
of an entity’s property or stock, the Administrator may grant Awards in substitution for any options or other stock or stock-based awards granted before such merger or consolidation by such entity or its affiliate. Substitute Awards may be
granted on such terms as the Administrator deems appropriate, notwithstanding limitations on Awards in the Plan. Substitute Awards will not count against the Overall Share Limit (nor shall Shares subject to a Substitute Award be added to the Shares
available for Awards under the Plan as provided above), except that Shares acquired by exercise of substitute Incentive Stock Options will count against the maximum number of Shares that may be issued pursuant to the exercise of Incentive Stock
Options under the Plan. Additionally, in the event that a company acquired by the Company or any Subsidiary or with which the Company or any Subsidiary combines has shares available under a pre-existing plan
approved by stockholders and not adopted in contemplation of such acquisition or combination, the shares available for grant pursuant to the terms of such pre-existing plan (as adjusted, to the extent
appropriate, using the exchange ratio or other adjustment or valuation ratio or formula used in such acquisition or combination to determine the consideration payable to the holders of common stock of the entities party to such acquisition or
combination) may be used for Awards under the Plan and shall not reduce the Shares authorized for grant under the Plan (and Shares subject to such Awards shall not be added to the Shares available for Awards under the Plan as provided above);
provided that Awards using such available shares shall not be made after the date awards or grants could have been made under the terms of the pre-existing plan, absent the acquisition or combination, and
shall only be made to individuals who were not Employees or Directors prior to such acquisition or combination. 
 4.5 Non-Employee Director Compensation. Notwithstanding any provision to the contrary in the Plan, the Administrator may establish compensation for non-employee Directors from
time to time, subject to the limitations in the Plan. The Administrator will from time to time determine the terms, conditions and amounts of all such non-employee Director compensation in its discretion and
pursuant to the exercise of its business judgment, taking into account such factors, circumstances and considerations as it shall deem relevant from time to time, provided that the sum of any cash compensation, or other compensation, and the value
(determined as of the grant date in accordance with Financial Accounting Standards Board Accounting Standards Codification Topic 718, or any successor thereto) of Awards granted to a non-employee Director as
compensation for services as a non-employee Director during any fiscal year of the Company may not exceed $750,000, increased to $1,000,000 in the fiscal year in which the Plan’s effective date occurs or
in the fiscal year of a non-employee Director’s initial service as a non-employee Director. The Administrator may make exceptions to this limit for individual non-employee Directors in extraordinary circumstances, as the Administrator may determine in its discretion, provided that the non-employee Director receiving such additional
compensation may not participate in the decision to award such compensation or in other contemporaneous compensation decisions involving non-employee Directors. 

  
 2 

 ARTICLE V. 

STOCK OPTIONS AND STOCK APPRECIATION RIGHTS 

5.1 General. The Administrator may grant Options or Stock Appreciation Rights to Service Providers subject to the limitations in the
Plan, including any limitations in the Plan that apply to Incentive Stock Options. The Administrator will determine the number of Shares covered by each Option and Stock Appreciation Right, the exercise price of each Option and Stock Appreciation
Right and the conditions and limitations applicable to the exercise of each Option and Stock Appreciation Right. A Stock Appreciation Right will entitle the Participant (or other person entitled to exercise the Stock Appreciation Right) to receive
from the Company upon exercise of the exercisable portion of the Stock Appreciation Right an amount determined by multiplying the excess, if any, of the Fair Market Value of one Share on the date of exercise over the exercise price per Share of the
Stock Appreciation Right by the number of Shares with respect to which the Stock Appreciation Right is exercised, subject to any limitations of the Plan or that the Administrator may impose and payable in cash, Shares valued at Fair Market Value or
a combination of the two as the Administrator may determine or provide in the Award Agreement. 
 5.2 Exercise Price. The
Administrator will establish each Option’s and Stock Appreciation Right’s exercise price and specify the exercise price in the Award Agreement. The exercise price will not be less than 100% of the Fair Market Value on the grant date of the
Option or Stock Appreciation Right. 
 5.3 Duration. Each Option or Stock Appreciation Right will be exercisable at such times and as
specified in the Award Agreement, provided that the term of an Option or Stock Appreciation Right will not exceed ten years. Notwithstanding the foregoing and unless determined otherwise by the Company, in the event that on the last business day of
the term of an Option or Stock Appreciation Right (other than an Incentive Stock Option) (i) the exercise of the Option or Stock Appreciation Right is prohibited by Applicable Law, as determined by the Company, or (ii) Shares may not be
purchased or sold by the applicable Participant due to any Company insider trading policy (including blackout periods) or a “lock-up” agreement undertaken in connection with an issuance of securities
by the Company, the term of the Option or Stock Appreciation Right shall be extended until the date that is thirty (30) days after the end of the legal prohibition, black-out period or lock-up agreement, as determined by the Company; provided, however, in no event shall the extension last beyond the ten year term of the applicable Option or Stock Appreciation Right. Notwithstanding the foregoing,
if the Participant, prior to the end of the term of an Option or Stock Appreciation Right, violates the non-competition, non-solicitation, confidentiality or other
similar restrictive covenant provisions of any employment contract, confidentiality and nondisclosure agreement or other agreement between the Participant and the Company or any of its Subsidiaries, the right of the Participant and the
Participant’s transferees to exercise any Option or Stock Appreciation Right issued to the Participant shall terminate immediately upon such violation, unless the Company otherwise determines. In addition, if, prior to the end of the term of an
Option or Stock Appreciation Right, the Participant is given notice by the Company or any of its Subsidiaries of the Participant’s Termination of Service by the Company or any of its Subsidiaries for Cause, and the effective date of such
Termination of Service is subsequent to the date of the delivery of such notice, the right of the Participant and the Participant’s transferees to exercise any Option or Stock Appreciation Right issued to the Participant shall be suspended from
the time of the delivery of such notice until the earlier of (i) such time as it is determined or otherwise agreed that the Participant’s service as a Service Provider will not be terminated for Cause as provided in such notice or
(ii) the effective date of the Participant’s Termination of Service by the Company or any of its Subsidiaries for Cause (in which case the right of the Participant and the Participant’s transferees to exercise any Option or Stock
Appreciation Right issued to the Participant will terminate immediately upon the effective date of such termination of Service). 

  
 3 

 5.4 Exercise. Options and Stock Appreciation Rights may be exercised by delivering to
the Company a written notice of exercise, in a form the Administrator approves (which may be electronic), signed by the person authorized to exercise the Option or Stock Appreciation Right, together with, as applicable, payment in full (i) as
specified in Section 5.5 for the number of Shares for which the Award is exercised and (ii) as specified in Section 9.5 for any applicable taxes. Unless the Administrator otherwise determines, an Option or Stock Appreciation Right may
not be exercised for a fraction of a Share. 
 5.5 Payment Upon Exercise. Subject to Section 10.8, any Company insider trading
policy (including blackout periods) and Applicable Laws, the exercise price of an Option must be paid by: 
 (a) cash, wire transfer of
immediately available funds or by check payable to the order of the Company, provided that the Company may limit the use of one of the foregoing payment forms if one or more of the payment forms below is permitted; 

(b) if there is a public market for Shares at the time of exercise, unless the Company otherwise determines, (A) delivery (including
telephonically to the extent permitted by the Company) of an irrevocable and unconditional undertaking by a broker acceptable to the Company to deliver promptly to the Company sufficient funds to pay the exercise price, or (B) the
Participant’s delivery to the Company of a copy of irrevocable and unconditional instructions to a broker acceptable to the Company to deliver promptly to the Company cash or a check sufficient to pay the exercise price; provided that such
amount is paid to the Company at such time as may be required by the Administrator; 
 (c) to the extent permitted by the Administrator,
delivery (either by actual delivery or attestation) of Shares owned by the Participant valued at their Fair Market Value; 
 (d) to the
extent permitted by the Administrator, surrendering Shares then issuable upon the Option’s exercise valued at their Fair Market Value on the exercise date; 

(e) to the extent permitted by the Administrator, delivery of a promissory note or any other property that the Administrator determines is good
and valuable consideration; or 
 (f) to the extent permitted by the Company, any combination of the above payment forms approved by the
Administrator. 
 ARTICLE VI. 

RESTRICTED STOCK; RESTRICTED STOCK UNITS 

6.1 General. The Administrator may grant Restricted Stock, or the right to purchase Restricted Stock, to any Service Provider, subject
to the Company’s right to repurchase all or part of such shares at their issue price or other stated or formula price from the Participant (or to require forfeiture of such shares) if conditions the Administrator specifies in the Award
Agreement are not satisfied before the end of the applicable restriction period or periods that the Administrator establishes for such Award. In addition, the Administrator may grant to Service Providers Restricted Stock Units, which may be subject
to vesting and forfeiture conditions during the applicable restriction period or periods, as set forth in an Award Agreement. The Administrator will determine and set forth in the Award Agreement the terms and conditions for each Restricted Stock
and Restricted Stock Unit Award, subject to the conditions and limitations contained in the Plan. 
 6.2 Restricted Stock. 

  
 4 

 (a) Dividends. Participants holding shares of Restricted Stock will be entitled to
all ordinary cash dividends paid with respect to such Shares, unless the Administrator provides otherwise in the Award Agreement. In addition, unless the Administrator provides otherwise, if any dividends or distributions are paid in Shares, or
consist of a dividend or distribution to holders of Common Stock of property other than an ordinary cash dividend, the Shares or other property will be subject to the same restrictions on transferability and forfeitability as the shares of
Restricted Stock with respect to which they were paid. 
 (b) Stock Certificates. The Company may require that the Participant deposit
in escrow with the Company (or its designee) any stock certificates issued in respect of shares of Restricted Stock, together with a stock power endorsed in blank. 

6.3 Restricted Stock Units. 

(a) Settlement. The Administrator may provide that settlement of Restricted Stock Units will occur upon or as soon as reasonably
practicable after the Restricted Stock Units vest or will instead be deferred, on a mandatory basis or at the Participant’s election, in a manner intended to comply with Section 409A. 

(b) Stockholder Rights. A Participant will have no rights of a stockholder with respect to Shares subject to any Restricted Stock Unit
unless and until the Shares are delivered in settlement of the Restricted Stock Unit. 
 (c) Dividend Equivalents. If the
Administrator provides, a grant of Restricted Stock Units may provide a Participant with the right to receive Dividend Equivalents. Dividend Equivalents may be paid currently or credited to an account for the Participant, settled in cash or Shares
and subject to the same restrictions on transferability and forfeitability as the Restricted Stock Units with respect to which the Dividend Equivalents are granted and subject to other terms and conditions as set forth in the Award Agreement. 

ARTICLE VII. 
 OTHER
STOCK OR CASH BASED AWARDS 
 Other Stock or Cash Based Awards may be granted to Participants, including Awards entitling Participants
to receive Shares to be delivered in the future and including annual or other periodic or long-term cash bonus awards (whether based on specified Performance Criteria or otherwise), in each case subject to any conditions and limitations in the Plan.
Such Other Stock or Cash Based Awards will also be available as a payment form in the settlement of other Awards, as standalone payments and as payment in lieu of compensation to which a Participant is otherwise entitled. Other Stock or Cash Based
Awards may be paid in Shares, cash or other property, as the Administrator determines. Subject to the provisions of the Plan, the Administrator will determine the terms and conditions of each Other Stock or Cash Based Award, including any purchase
price, performance goal (which may be based on the Performance Criteria), transfer restrictions, and vesting conditions, which will be set forth in the applicable Award Agreement. 

ARTICLE VIII. 

ADJUSTMENTS FOR CHANGES IN COMMON STOCK 

AND CERTAIN OTHER EVENTS 

  
 5 

 8.1 Equity Restructuring(a) . In connection with any Equity Restructuring,
notwithstanding anything to the contrary in this Article VIII, the Administrator will equitably adjust each outstanding Award as it deems appropriate to reflect the Equity Restructuring, which may include adjusting the number and type of
securities subject to each outstanding Award and/or the Award’s exercise price or grant price (if applicable), granting new Awards to Participants, and making a cash payment to Participants. The adjustments provided under this Section 8.1
will be nondiscretionary and final and binding on the affected Participant and the Company; provided that the Administrator will determine whether an adjustment is equitable. 

8.2 Corporate Transactions. In the event of any dividend or other distribution (whether in the form of cash, Common Stock, other
securities, or other property), reorganization, merger, consolidation, combination, amalgamation, repurchase, recapitalization, liquidation, dissolution, or sale, transfer, exchange or other disposition of all or substantially all of the assets of
the Company, or sale or exchange of Common Stock or other securities of the Company, Change in Control, issuance of warrants or other rights to purchase Common Stock or other securities of the Company, other similar corporate transaction or event,
other unusual or nonrecurring transaction or event affecting the Company or its financial statements or any change in any Applicable Laws or accounting principles, the Administrator, on such terms and conditions as it deems appropriate, either by
the terms of the Award or by action taken prior to the occurrence of such transaction or event (except that action to give effect to a change in Applicable Law or accounting principles may be made within a reasonable period of time after such
change) and either automatically or upon the Participant’s request, is hereby authorized to take any one or more of the following actions whenever the Administrator determines that such action is appropriate in order to (x) prevent
dilution or enlargement of the benefits or potential benefits intended by the Company to be made available under the Plan or with respect to any Award granted or issued under the Plan, (y) to facilitate such transaction or event or
(z) give effect to such changes in Applicable Laws or accounting principles: 
 (a) To provide for the cancellation of any such Award in
exchange for either an amount of cash or other property with a value equal to the amount that could have been obtained upon the exercise or settlement of the vested portion of such Award or realization of the Participant’s rights under the
vested portion of such Award, as applicable; provided that, if the amount that could have been obtained upon the exercise or settlement of the vested portion of such Award or realization of the Participant’s rights, in any case, is equal to or
less than zero, then the Award may be terminated without payment; 
 (b) To provide that such Award shall vest and, to the extent applicable,
be exercisable as to all shares covered thereby, notwithstanding anything to the contrary in the Plan or the provisions of such Award; 
 (c)
To provide that such Award be assumed by the successor or survivor corporation, or a parent or subsidiary thereof, or shall be substituted for by awards covering the stock of the successor or survivor corporation, or a parent or subsidiary thereof,
with appropriate adjustments as to the number and kind of shares and/or applicable exercise or purchase price, in all cases, as determined by the Administrator; 

(d) To make adjustments in the number and type of shares of Common Stock (or other securities or property) subject to outstanding Awards and/or
with respect to which Awards may be granted under the Plan (including, but not limited to, adjustments of the limitations in Article IV hereof on the maximum number and kind of shares which may be issued) and/or in the terms and conditions of
(including the grant or exercise price), and the criteria included in, outstanding Awards; 
 (e) To replace such Award with other rights or
property selected by the Administrator; and/or 

  
 6 

 (f) To provide that the Award will terminate and cannot vest, be exercised or become payable
after the applicable event. 
 8.3 Administrative Stand Still. In the event of any pending stock dividend, stock split, combination
or exchange of shares, merger, consolidation or other distribution (other than normal cash dividends) of Company assets to stockholders, or any other extraordinary transaction or change affecting the Shares or the share price of Common Stock,
including any Equity Restructuring or any securities offering or other similar transaction, for administrative convenience, the Administrator may refuse to permit the exercise of any Award for up to sixty days before or after such transaction. 

8.4 General. Except as expressly provided in the Plan or the Administrator’s action under the Plan, no Participant will have any
rights due to any subdivision or consolidation of Shares of any class, dividend payment, increase or decrease in the number of Shares of any class or dissolution, liquidation, merger, or consolidation of the Company or other corporation. Except as
expressly provided with respect to an Equity Restructuring under Section 8.1 above or the Administrator’s action under the Plan, no issuance by the Company of Shares of any class, or securities convertible into Shares of any class, will
affect, and no adjustment will be made regarding, the number of Shares subject to an Award or the Award’s grant or exercise price. The existence of the Plan, any Award Agreements and the Awards granted hereunder will not affect or restrict in
any way the Company’s right or power to make or authorize (i) any adjustment, recapitalization, reorganization or other change in the Company’s capital structure or its business, (ii) any merger, consolidation dissolution or
liquidation of the Company or sale of Company assets or (iii) any sale or issuance of securities, including securities with rights superior to those of the Shares or securities convertible into or exchangeable for Shares. The Administrator may
treat Participants and Awards (or portions thereof) differently under this Article VIII. 
 ARTICLE IX. 

GENERAL PROVISIONS APPLICABLE TO AWARDS 

9.1 Transferability. Except as the Administrator may determine or provide in an Award Agreement or otherwise for Awards other than
Incentive Stock Options, Awards may not be sold, assigned, transferred, pledged or otherwise encumbered, either voluntarily or by operation of law, except by will or the laws of descent and distribution, or, subject to the Administrator’s
consent, pursuant to a domestic relations order, and, during the life of the Participant, will be exercisable only by the Participant. References to a Participant, to the extent relevant in the context, will include references to a
Participant’s authorized transferee that the Administrator specifically approves. 
 9.2 Documentation. Each Award will be
evidenced in an Award Agreement, which may be written or electronic, as the Administrator determines. Each Award may contain terms and conditions in addition to those set forth in the Plan. 

9.3 Discretion. Except as the Plan otherwise provides, each Award may be made alone or in addition or in relation to any other Award.
The terms of each Award to a Participant need not be identical, and the Administrator need not treat Participants or Awards (or portions thereof) uniformly. 

9.4 Termination of Status. The Administrator will determine how the disability, death, retirement, authorized leave of absence or any
other change or purported change in a Participant’s Service Provider status affects an Award and the extent to which, and the period during which, the Participant, the Participant’s legal representative, conservator, guardian or Designated
Beneficiary may exercise rights under the Award, if applicable. 

  
 7 

 9.5 Withholding. Each Participant must pay the Company, or make provision
satisfactory to the Administrator for payment of, any taxes required by law to be withheld in connection with such Participant’s Awards by the date of the event creating the tax liability. The Company may deduct an amount sufficient to satisfy
such tax obligations based on the applicable statutory withholding rates (or such other rate as may be determined by the Company after considering any accounting consequences or costs) from any payment of any kind otherwise due to a Participant.
Subject to Section 10.8 and any Company insider trading policy (including blackout periods), Participants may satisfy such tax obligations (i) in cash, by wire transfer of immediately available funds, by check made payable to the order of
the Company, provided that the Company may limit the use of the foregoing payment forms if one or more of the payment forms below is permitted, (ii) to the extent permitted by the Administrator, in whole or in part by delivery of Shares,
including Shares retained from the Award creating the tax obligation, valued at their Fair Market Value, (iii) if there is a public market for Shares at the time the tax obligations are satisfied, unless the Company otherwise determines,
(A) delivery (including telephonically to the extent permitted by the Company) of an irrevocable and unconditional undertaking by a broker acceptable to the Company to deliver promptly to the Company sufficient funds to satisfy the tax
obligations, or (B) delivery by the Participant to the Company of a copy of irrevocable and unconditional instructions to a broker acceptable to the Company to deliver promptly to the Company cash or a check sufficient to satisfy the tax
withholding; provided that such amount is paid to the Company at such time as may be required by the Administrator, or (iv) to the extent permitted by the Company, any combination of the foregoing payment forms approved by the Administrator. If
any tax withholding obligation will be satisfied under clause (ii) of the immediately preceding sentence by the Company’s retention of Shares from the Award creating the tax obligation and there is a public market for Shares at the time
the tax obligation is satisfied, the Company may elect to instruct any brokerage firm determined acceptable to the Company for such purpose to sell on the applicable Participant’s behalf some or all of the Shares retained and to remit the
proceeds of the sale to the Company or its designee, and each Participant’s acceptance of an Award under the Plan will constitute the Participant’s authorization to the Company and instruction and authorization to such brokerage firm to
complete the transactions described in this sentence. 
 9.6 Amendment of Award; Repricing. The Administrator may amend, modify or
terminate any outstanding Award, including by substituting another Award of the same or a different type, changing the exercise or settlement date, and converting an Incentive Stock Option to a Non-Qualified
Stock Option. The Participant’s consent to such action will be required unless (i) the action, taking into account any related action, does not materially and adversely affect the Participant’s rights under the Award, or (ii) the
change is permitted under Article VIII or pursuant to Section 10.6. Further, the Administrator may, without the approval of the stockholders of the Company, reduce the exercise price per share of outstanding Options or Stock Appreciation
Rights or cancel outstanding Options or Stock Appreciation Rights in exchange for cash, other Awards or Options or Stock Appreciation Rights with an exercise price per share that is less than the exercise price per share of the original Options or
Stock Appreciation Rights. 
 9.7 Conditions on Delivery of Stock. The Company will not be obligated to deliver any Shares under the
Plan or remove restrictions from Shares previously delivered under the Plan until (i) all Award conditions have been met or removed to the Company’s satisfaction, (ii) as determined by the Company, all other legal matters regarding
the issuance and delivery of such Shares have been satisfied, including any applicable securities laws and 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 Administrator deems necessary or appropriate to satisfy any Applicable Laws. The Company’s inability to obtain authority from any regulatory body having jurisdiction, which the Administrator determines is
necessary to the lawful issuance and sale of any securities, will relieve the Company of any liability for failing to issue or sell such Shares as to which such requisite authority has not been obtained. 

  
 8 

 9.8 Acceleration. The Administrator may at any time provide that any Award will
become immediately vested and fully or partially exercisable, free of some or all restrictions or conditions, or otherwise fully or partially realizable. 

9.9 Additional Terms of Incentive Stock Options. The Administrator may grant Incentive Stock Options only to employees of the Company,
any of its present or future parent or subsidiary corporations, as defined in Sections 424(e) or (f) of the Code, respectively, and any other entities the employees of which are eligible to receive Incentive Stock Options under the Code.
If an Incentive Stock Option is granted to a Greater Than 10% Stockholder, the exercise price will not be less than 110% of the Fair Market Value on the Option’s grant date, and the term of the Option will not exceed five years. All Incentive
Stock Options will be subject to and construed consistently with Section 422 of the Code. By accepting an Incentive Stock Option, the Participant agrees to give prompt notice to the Company of dispositions or other transfers (other than in
connection with a Change in Control) of Shares acquired under the Option made within (i) two years from the grant date of the Option or (ii) one year after the transfer of such Shares to the Participant, specifying the date of the
disposition or other transfer and the amount the Participant realized, in cash, other property, assumption of indebtedness or other consideration, in such disposition or other transfer. Neither the Company nor the Administrator will be liable to a
Participant, or any other party, if an Incentive Stock Option fails or ceases to qualify as an “incentive stock option” under Section 422 of the Code. Any Incentive Stock Option or portion thereof that fails to qualify as an
“incentive stock option” under Section 422 of the Code for any reason, including becoming exercisable with respect to Shares having a fair market value exceeding the $100,000 limitation under Treasury Regulation Section 1.422-4, will be a Non-Qualified Stock Option. 

ARTICLE X. 

MISCELLANEOUS 
 10.1 No
Right to Employment or Other Status. No person will have any claim or right to be granted an Award, and the grant of an Award will 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 or any Award, except as expressly provided in an Award Agreement.

 10.2 No Rights as Stockholder; Certificates. Subject to the Award Agreement, no Participant or Designated Beneficiary will have
any rights as a stockholder with respect to any Shares to be distributed under an Award until becoming the record holder of such Shares. Notwithstanding any other provision of the Plan, unless the Administrator otherwise determines or Applicable
Laws require, the Company will not be required to deliver to any Participant certificates evidencing Shares issued in connection with any Award and instead such Shares may be recorded in the books of the Company (or, as applicable, its transfer
agent or stock plan administrator). The Company may place legends on stock certificates issued under the Plan that the Administrator deems necessary or appropriate to comply with Applicable Laws. 

10.3 Effective Date and Term of Plan. Unless earlier terminated by the Board, the Plan will become effective on the day prior to the
Public Trading Date and will remain in effect until the tenth anniversary of the earlier of (i) the date the Board adopted the Plan or (ii) the date the Company’s stockholders approved the Plan, but Awards previously granted may
extend beyond that date in accordance with the Plan. If the Plan is not approved by the Company’s stockholders, the Plan will not become effective, no Awards will be granted under the Plan and the Prior Plans will continue in full force and
effect in accordance with their terms. 

  
 9 

 10.4 Amendment of Plan. The Administrator may amend, suspend or terminate the Plan at
any time; provided that no amendment, other than an increase to the Overall Share Limit, may materially and adversely affect any Award outstanding at the time of such amendment without the affected Participant’s consent. No Awards may be
granted under the Plan during any suspension period or after Plan termination. Awards outstanding at the time of any Plan suspension or termination will continue to be governed by the Plan and the Award Agreement, as in effect before such suspension
or termination. The Board will obtain stockholder approval of any Plan amendment to the extent necessary to comply with Applicable Laws. 

10.5 Provisions for Foreign Participants. The Administrator may modify Awards granted to Participants who are foreign nationals or
employed outside the United States or establish subplans or procedures under the Plan to address differences in laws, rules, regulations or customs of such foreign jurisdictions with respect to tax, securities, currency, employee benefit or other
matters. 
 10.6 Section 409A. 

(a) General. The Company intends that all Awards be structured to comply with, or be exempt from, Section 409A, such that no
adverse tax consequences, interest, or penalties under Section 409A apply. Notwithstanding anything in the Plan or any Award Agreement to the contrary, the Administrator may, without a Participant’s consent, amend this Plan or Awards,
adopt policies and procedures, or take any other actions (including amendments, policies, procedures and retroactive actions) as are necessary or appropriate to preserve the intended tax treatment of Awards, including any such actions intended to
(A) exempt this Plan or any Award from Section 409A, or (B) comply with Section 409A, including regulations, guidance, compliance programs and other interpretative authority that may be issued after an Award’s grant date.
The Company makes no representations or warranties as to an Award’s tax treatment under Section 409A or otherwise. The Company will have no obligation under this Section 10.6 or otherwise to avoid the taxes, penalties or interest
under Section 409A with respect to any Award and will have no liability to any Participant or any other person if any Award, compensation or other benefits under the Plan are determined to constitute noncompliant “nonqualified deferred
compensation” subject to taxes, penalties or interest under Section 409A. 
 (b) Separation from Service. If an Award
constitutes “nonqualified deferred compensation” under Section 409A, any payment or settlement of such Award upon a termination of a Participant’s Service Provider relationship will, to the extent necessary to avoid taxes under
Section 409A, be made only upon the Participant’s “separation from service” (within the meaning of Section 409A), whether such “separation from service” occurs upon or after the termination of the
Participant’s Service Provider relationship. For purposes of this Plan or any Award Agreement relating to any such payments or benefits, references to a “termination,” “termination of employment” or like terms means a
“separation from service.” 
 (c) Payments to Specified Employees. Notwithstanding any contrary provision in the Plan or any
Award Agreement, any payment(s) of “nonqualified deferred compensation” required to be made under an Award to a “specified employee” (as defined under Section 409A and as the Administrator determines) due to his or her
“separation from service” will, to the extent necessary to avoid taxes under Section 409A(a)(2)(B)(i) of the Code, be delayed for the six-month period immediately following such “separation
from service” (or, if earlier, until the specified employee’s death) and will instead be paid (as set forth in the Award Agreement) on the day immediately following such six-month period or as soon
as administratively practicable thereafter (without interest). Any payments of “nonqualified deferred compensation” under such Award payable more than six months following the Participant’s “separation from service” will be
paid at the time or times the payments are otherwise scheduled to be made. 

  
 10 

 10.7 Limitations on Liability. Notwithstanding any other provisions of the Plan, no
individual acting as a director, officer, other employee or agent of the Company or any Subsidiary 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 or any Award, and such individual will not be personally liable with respect to the Plan because of any contract or other instrument executed in his or her capacity as an Administrator, director, officer, other employee or
agent of the Company or any Subsidiary. The Company will indemnify and hold harmless each director, officer, other employee and agent of the Company or any Subsidiary that has been or will be granted or delegated any duty or power relating to the
Plan’s administration or interpretation, against any cost or expense (including attorneys’ fees) or liability (including any sum paid in settlement of a claim with the Administrator’s approval) arising from any act or omission
concerning this Plan unless arising from such person’s own fraud or bad faith. 
 10.8
Lock-Up Period. The Company may, at the request of any underwriter representative or otherwise, in connection with registering the offering of any Company securities under the Securities Act, prohibit
Participants from, directly or indirectly, selling or otherwise transferring any Shares or other Company securities during a period of up to one hundred eighty days following the effective date of a Company registration statement filed under the
Securities Act, or such longer period as determined by the underwriter. 
 10.9 Data Privacy. As a condition for receiving any Award,
each Participant explicitly and unambiguously consents to the collection, use and transfer, in electronic or other form, of personal data as described in this section by and among the Company and its Subsidiaries and affiliates exclusively for
implementing, administering and managing the Participant’s participation in the Plan. The Company and its Subsidiaries and affiliates may hold certain personal information about a Participant, including the Participant’s name, address and
telephone number; birthdate; social security, insurance number or other identification number; salary; nationality; job title(s); any Shares held in the Company or its Subsidiaries and affiliates; and Award details, to implement, manage and
administer the Plan and Awards (the “Data”). The Company and its Subsidiaries and affiliates may transfer the Data amongst themselves as necessary to implement, administer and manage a Participant’s participation in the
Plan, and the Company and its Subsidiaries and affiliates may transfer the Data to third parties assisting the Company with Plan implementation, administration and management. These recipients may be located in the Participant’s country, or
elsewhere, and the Participant’s country may have different data privacy laws and protections than the recipients’ country. By accepting an Award, each Participant authorizes such recipients to receive, possess, use, retain and transfer
the Data, in electronic or other form, to implement, administer and manage the Participant’s participation in the Plan, including any required Data transfer to a broker or other third party with whom the Company or the Participant may elect to
deposit any Shares. The Data related to a Participant will be held only as long as necessary to implement, administer, and manage the Participant’s participation in the Plan. A Participant may, at any time, view the Data that the Company holds
regarding such Participant, request additional information about the storage and processing of the Data regarding such Participant, recommend any necessary corrections to the Data regarding the Participant or refuse or withdraw the consents in this
Section 10.9 in writing, without cost, by contacting the local human resources representative. The Company may cancel Participant’s ability to participate in the Plan and, in the Administrator’s discretion, the Participant may forfeit
any outstanding Awards if the Participant refuses or withdraws the consents in this Section 10.9. For more information on the consequences of refusing or withdrawing consent, Participants may contact their local human resources representative.

 10.10 Severability. If any portion of the Plan or any action taken under it is held illegal or invalid for any reason, the
illegality or invalidity will not affect the remaining parts of the Plan, and the Plan will be construed and enforced as if the illegal or invalid provisions had been excluded, and the illegal or invalid action will be null and void. 

  
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 10.11 Governing Documents. If any contradiction occurs between the Plan and any Award
Agreement or other written agreement between a Participant and the Company (or any Subsidiary) that the Administrator has approved, the Plan will govern, unless it is expressly specified in such Award Agreement or other written document that a
specific provision of the Plan will not apply. 
 10.12 Governing Law. The Plan and all Awards will be governed by and interpreted in
accordance with the laws of the State of Delaware, disregarding any state’s choice-of-law principles requiring the application of a jurisdiction’s laws other
than the State of Delaware. 
 10.13 Claw-back Provisions. All Awards (including any proceeds, gains or other economic benefit the
Participant actually or constructively receives upon receipt or exercise of any Award or the receipt or resale of any Shares underlying the Award) will be subject to any Company claw-back policy, including any claw-back policy adopted to comply with
Applicable Laws (including the Dodd-Frank Wall Street Reform and Consumer Protection Act and any rules or regulations promulgated thereunder) as set forth in such claw-back policy or the Award Agreement. 

10.14 Titles and Headings. The titles and headings in the Plan are for convenience of reference only and, if any conflict, the
Plan’s text, rather than such titles or headings, will control. 
 10.15 Conformity to Securities Laws. Participant acknowledges
that the Plan is intended to conform to the extent necessary with Applicable Laws. Notwithstanding anything herein to the contrary, the Plan and all Awards will be administered only in conformance with Applicable Laws. To the extent Applicable Laws
permit, the Plan and all Award Agreements will be deemed amended as necessary to conform to Applicable Laws. 
 10.16 Relationship to
Other Benefits. No payment under the Plan will be taken into account in determining any benefits under any pension, retirement, savings, profit sharing, group insurance, welfare or other benefit plan of the Company or any Subsidiary except as
expressly provided in writing in such other plan or an agreement thereunder. 
 10.17 Broker-Assisted Sales. In the event of a
broker-assisted sale of Shares in connection with the payment of amounts owed by a Participant under or with respect to the Plan or Awards, including amounts to be paid under the final sentence of Section 9.5: (a) any Shares to be sold through
the broker-assisted sale will be sold on the day the payment first becomes due, or as soon thereafter as practicable; (b) such Shares may be sold as part of a block trade with other Participants in the Plan in which all participants receive an
average price; (c) the applicable Participant will be responsible for all broker’s fees and other costs of sale, and by accepting an Award, each Participant agrees to indemnify and hold the Company harmless from any losses, costs, damages,
or expenses relating to any such sale; (d) to the extent the Company or its designee receives proceeds of such sale that exceed the amount owed, the Company will pay such excess in cash to the applicable Participant as soon as reasonably
practicable; (e) the Company and its designees are under no obligation to arrange for such sale at any particular price; and (f) in the event the proceeds of such sale are insufficient to satisfy the Participant’s applicable
obligation, the Participant may be required to pay immediately upon demand to the Company or its designee an amount in cash sufficient to satisfy any remaining portion of the Participant’s obligation. 

  
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 ARTICLE XI. 

DEFINITIONS 
 As used in
the Plan, the following words and phrases will have the following meanings: 
 11.1 “Administrator” means the Board
or a Committee to the extent that the Board’s powers or authority under the Plan have been delegated to such Committee. 
 11.2
“Applicable Laws” means the requirements relating to the administration of equity incentive plans under U.S. federal and state securities, tax and other applicable laws, rules and regulations, the applicable rules of any
stock exchange or quotation system on which the Common Stock is listed or quoted and the applicable laws and rules of any foreign country or other jurisdiction where Awards are granted. 

11.3 “Award” means, individually or collectively, a grant under the Plan of Options, Stock Appreciation Rights,
Restricted Stock, Restricted Stock Units or Other Stock or Cash Based Awards. 
 11.4 “Award Agreement” means a
written agreement evidencing an Award, which may be electronic, that contains such terms and conditions as the Administrator determines, consistent with and subject to the terms and conditions of the Plan. 

11.5 “Board” means the Board of Directors of the Company. 

11.6 “Cause” means (i) if a Participant is a party to a written employment or consulting agreement with the
Company or any of its Subsidiaries or an Award Agreement in which the term “cause” is defined (a “Relevant Agreement”), “Cause” as defined in the Relevant Agreement, and (ii) if no Relevant Agreement
exists, (A) the Administrator’s determination that the Participant failed to substantially perform the Participant’s duties (other than a failure resulting from the Participant’s Disability); (B) the Administrator’s
determination that the Participant failed to carry out, or comply with any lawful and reasonable directive of the Board or the Participant’s immediate supervisor; (C) the occurrence of any act or omission by the Participant that could
reasonably be expected to result in (or has resulted in) the Participant’s conviction, plea of no contest, plea of nolo contendere, or imposition of unadjudicated probation for any felony or indictable offense or crime involving moral
turpitude; (D) the Participant’s unlawful use (including being under the influence) or possession of illegal drugs on the premises of the Company or any of its Subsidiaries or while performing the Participant’s duties and
responsibilities for the Company or any of its Subsidiaries; or (E) the Administrator’s determination that the Participant committed an act of fraud, embezzlement, misappropriation, or misconduct, or breached a fiduciary duty against the
Company or any of its Subsidiaries. 
 11.7 “Change in Control” means and includes each of the following: 

(a) A transaction or series of transactions (other than an offering of Common Stock to the general public through a registration statement
filed with the Securities and Exchange Commission or a transaction or series of transactions that meets the requirements of clauses (i) and (ii) of subsection (c) below) whereby any “person” or related “group” of
“persons” (as such terms are used in Sections 13(d) and 14(d)(2) of the Exchange Act) (other than the Company, any of its Subsidiaries, an employee benefit plan maintained by the Company or any of its Subsidiaries or a
“person” that, prior to such transaction, directly or indirectly controls, is controlled by, or is under common control with, the Company) directly or indirectly acquires beneficial ownership (within the meaning of Rule 13d-3 under the Exchange Act) of securities of the Company possessing more than 50% of the total combined voting power of the Company’s securities outstanding immediately after such acquisition; or 

(b) During any period of two consecutive years, individuals who, at the beginning of such period, constitute the Board together with any new
Director(s) (other than a Director designated by a person who shall have entered into an agreement with the Company to effect a transaction described in subsections (a) or (c)) whose election by the Board or nomination for election by the
Company’s stockholders was approved by a vote of at least two-thirds of the Directors then still in office who either were Directors at the beginning of the
two-year period or whose election or nomination for election was previously so approved, cease for any reason to constitute a majority thereof; or 

  
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 (c) The consummation by the Company (whether directly involving the Company or indirectly
involving the Company through one or more intermediaries) of (x) a merger, consolidation, reorganization, or business combination or (y) a sale or other disposition of all or substantially all of the Company’s assets in any single
transaction or series of related transactions or (z) the acquisition of assets or stock of another entity, in each case other than a transaction: 

(i) which results in the Company’s voting securities outstanding immediately before the transaction continuing to represent (either by
remaining outstanding or by being converted into voting securities of the Company or the person that, as a result of the transaction, controls, directly or indirectly, the Company or owns, directly or indirectly, all or substantially all of the
Company’s assets or otherwise succeeds to the business of the Company (the Company or such person, the “Successor Entity”)) directly or indirectly, at least a majority of the combined voting power of the Successor
Entity’s outstanding voting securities immediately after the transaction, and 
 (ii) after which no person or group beneficially owns
voting securities representing 50% or more of the combined voting power of the Successor Entity; provided, however, that no person or group shall be treated for purposes of this clause (ii) as beneficially owning 50% or more of
the combined voting power of the Successor Entity solely as a result of the voting power held in the Company prior to the consummation of the transaction. 

Notwithstanding the foregoing, if a Change in Control constitutes a payment event with respect to any Award (or portion of any Award) that
provides for the deferral of compensation that is subject to Section 409A, to the extent required to avoid the imposition of additional taxes under Section 409A, the transaction or event described in subsection (a), (b) or
(c) with respect to such Award (or portion thereof) shall only constitute a Change in Control for purposes of the payment timing of such Award if such transaction also constitutes a “change in control event,” as defined in Treasury
Regulation Section 1.409A-3(i)(5). 
 The Administrator shall have full and final authority,
which shall be exercised in its discretion, to determine conclusively whether a Change in Control has occurred pursuant to the above definition, the date of the occurrence of such Change in Control and any incidental matters relating thereto;
provided that any exercise of authority in conjunction with a determination of whether a Change in Control is a “change in control event” as defined in Treasury Regulation Section 1.409A-3(i)(5)
shall be consistent with such regulation. 
 11.8 “Code” means the Internal Revenue Code of 1986, as amended, and
the regulations issued thereunder. 
 11.9 “Committee” means one or more committees or subcommittees of the Board,
which may include one or more Company directors or executive officers, to the extent Applicable Laws permit. To the extent required to comply with the provisions of Rule 16b-3, it is intended that each member
of the Committee will be, at the time the Committee takes any action with respect to an Award that is subject to Rule 16b-3, a “non-employee director” within
the meaning of Rule 16b-3; however, a Committee member’s failure to qualify as a “non-employee director” within the meaning of Rule 16b-3 will not invalidate any Award granted by the Committee that is otherwise validly granted under the Plan. 

11.10 “Common Stock” means the common stock of the Company. 

  
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 11.11 “Company” means SQZ Biotechnologies Company, a Delaware
corporation, or any successor. 
 11.12 “Consultant” means any person, including any adviser, engaged by the Company
or its parent or Subsidiary to render services to such entity if the consultant or adviser: (i) renders bona fide services to the Company; (ii) renders services not in connection with the offer or sale of securities in a capital-raising
transaction and does not directly or indirectly promote or maintain a market for the Company’s securities; and (iii) is a natural person. 

11.13 “Designated Beneficiary” means the beneficiary or beneficiaries the Participant designates, in a manner the
Administrator determines, to receive amounts due or exercise the Participant’s rights if the Participant dies or becomes incapacitated. Without a Participant’s effective designation, “Designated Beneficiary” will mean the
Participant’s estate. 
 11.14 “Director” means a Board member. 

11.15 “Disability” means a permanent and total disability under Section 22(e)(3) of the Code, as amended. 

11.16 “Dividend Equivalents” means a right granted to a Participant under the Plan to receive the equivalent value (in
cash or Shares) of dividends paid on Shares. 
 11.17 “Employee” means any employee of the Company or its
Subsidiaries. 
 11.18 “Equity Restructuring” means a nonreciprocal transaction between the Company and its
stockholders, such as a stock dividend, stock split, spin-off or recapitalization through a large, nonrecurring cash dividend, that affects the number or kind of Shares (or other Company securities) or the
share price of Common Stock (or other Company securities) and causes a change in the per share value of the Common Stock underlying outstanding Awards. 

11.19 “Exchange Act” means the Securities Exchange Act of 1934, as amended. 

11.20 “Fair Market Value” means, as of any date, the value of Common Stock determined as follows: (i) if the
Common Stock is listed on any established stock exchange, its Fair Market Value will be the closing sales price for such Common Stock as quoted on such exchange for such date, or if no sale occurred on such date, the last day preceding such date
during which a sale occurred, as reported in The Wall Street Journal or another source the Administrator deems reliable; (ii) if the Common Stock is not traded on a stock exchange but is quoted on a national market or other quotation system,
the closing sales price on such date, or if no sales occurred on such date, then on the last date preceding such date during which a sale occurred, as reported in The Wall Street Journal or another source the Administrator deems reliable; or
(iii) without an established market for the Common Stock, the Administrator will determine the Fair Market Value in its discretion. Notwithstanding the foregoing, with respect to any Award granted on the pricing date of the Company’s
initial public offering, the Fair Market Value shall mean the initial public offering price of a Share as set forth in the Company’s final prospectus relating to its initial public offering filed with the Securities and Exchange Commission.

 11.21 “Greater Than 10% Stockholder” means an individual then owning (within the meaning of Section 424(d)
of the Code) more than 10% of the total combined voting power of all classes of stock of the Company or its parent or subsidiary corporation, as defined in Section 424(e) and (f) of the Code, respectively. 

  
 15 

 11.22 “Incentive Stock Option” means an Option intended to qualify
as an “incentive stock option” as defined in Section 422 of the Code. 
 11.23
“Non-Qualified Stock Option” means an Option not intended or not qualifying as an Incentive Stock Option. 

11.24 “Option” means an option to purchase Shares. 

11.25 “Other Stock or Cash Based Awards” means cash awards, awards of Shares, and other awards valued wholly or
partially by referring to, or are otherwise based on, Shares or other property. 
 11.26 “Overall Share Limit” means
the sum of (i) 2,555,000 Shares; (ii) any shares of Common Stock which are subject to Prior Plan Awards which become available for issuance under the Plan pursuant to Article IV and (iii) an annual increase on the first day of each
calendar year beginning January 1, 2021 and ending on and including January 1, 2030, equal to the lesser of (A) 5% of the aggregate number of shares of Common Stock outstanding on the final day of the immediately preceding calendar year
and (B) such smaller number of Shares as is determined by the Board. 
 11.27 “Participant” means a Service
Provider who has been granted an Award. 
 11.28 “Performance Criteria” mean the criteria (and adjustments) that the
Administrator may select for an Award to establish performance goals for a performance period, which may include the following: net earnings or losses (either before or after one or more of interest, taxes, depreciation, amortization, and non-cash equity-based compensation expense); gross or net sales or revenue or sales or revenue growth; net income (either before or after taxes) or adjusted net income; profits (including but not limited to gross
profits, net profits, profit growth, net operation profit or economic profit), profit return ratios or operating margin; budget or operating earnings (either before or after taxes or before or after allocation of corporate overhead and bonus); cash
flow (including operating cash flow and free cash flow or cash flow return on capital); return on assets; return on capital or invested capital; cost of capital; return on stockholders’ equity; total stockholder return; return on sales; costs,
reductions in costs and cost control measures; expenses; working capital; earnings or loss per share; adjusted earnings or loss per share; price per share or dividends per share (or appreciation in or maintenance of such price or dividends);
regulatory achievements or compliance; implementation, completion or attainment of objectives relating to research, development, regulatory, commercial, or strategic milestones or developments; market share; economic value or economic value added
models; division, group or corporate financial goals; customer satisfaction/growth; customer service; employee satisfaction; recruitment and maintenance of personnel; human resources management; supervision of litigation and other legal matters;
strategic partnerships and transactions; financial ratios (including those measuring liquidity, activity, profitability or leverage); debt levels or reductions; sales-related goals; financing and other capital raising transactions; cash on hand; acquisition activity; investment sourcing activity; and marketing initiatives, any of which may be measured in absolute terms or as
compared to any incremental increase or decrease. Such performance goals also may be based solely by reference to the Company’s performance or the performance of a Subsidiary, division, business segment or business unit of the Company or a
Subsidiary, or based upon performance relative to performance of other companies or upon comparisons of any of the indicators of performance relative to performance of other companies. The Committee may provide for exclusion of the impact of an
event or occurrence which the Committee determines should appropriately be excluded, including (a) restructurings, discontinued operations, extraordinary items, and other unusual, infrequently occurring or
non-recurring charges or events, (b) asset write-downs, (c) litigation or claim judgments or settlements, (d) acquisitions or divestitures, (e) reorganization or change in the corporate
structure or capital structure of the Company, (f) an event either not directly related to the operations of the Company, Subsidiary, division, business segment or business 

  
 16 

 
unit or not within the reasonable control of management, (g) foreign exchange gains and losses, (h) a change in the fiscal year of the Company, (i) the refinancing or repurchase of
bank loans or debt securities, (j) unbudgeted capital expenditures, (k) the issuance or repurchase of equity securities and other changes in the number of outstanding shares, (l) conversion of some or all of convertible securities to
Common Stock, (m) any business interruption event (n) the cumulative effects of tax or accounting changes in accordance with U.S. generally accepted accounting principles, or (o) the effect of changes in other laws or regulatory rules
affecting reported results. 
 11.29 “Plan” means this 2020 Incentive Award Plan. 

11.30 “Prior Plans” means the SQZ Biotechnologies Company 2014 Stock Incentive Plan and any prior equity incentive
plans of the Company or its predecessor. 
 11.31 “Prior Plan Award” means an award outstanding under the Prior
Plans as of the Plan’s effective date in Section 10.3. 
 11.32 “Public Trading Date” means the first date
upon which the Common Stock is listed (or approved for listing) upon notice of issuance on any securities exchange or designated (or approved for designation) upon notice of issuance as a national market security on an interdealer quotation system,
or, if earlier, the date on which the Company becomes a “publicly held corporation” for purposes of Treasury Regulation Section 1.162-27(c)(1). 

11.33 “Restricted Stock” means Shares awarded to a Participant under Article VI subject to certain vesting
conditions and other restrictions. 
 11.34 “Restricted Stock Unit” means an unfunded, unsecured right to receive,
on the applicable settlement date, one Share or an amount in cash or other consideration determined by the Administrator to be of equal value as of such settlement date, subject to certain vesting conditions and other restrictions. 

11.35 “Rule 16b-3” means Rule 16b-3
promulgated under the Exchange Act. 
 11.36 “Section 409A” means Section 409A
of the Code and all regulations, guidance, compliance programs and other interpretative authority thereunder. 
 11.37
“Securities Act” means the Securities Act of 1933, as amended. 
 11.38 “Service Provider”
means an Employee, Consultant or Director. 
 11.39 “Shares” means shares of Common Stock. 

11.40 “Stock Appreciation Right” means a stock appreciation right granted under Article V. 

11.41 “Subsidiary” means any entity (other than the Company), whether domestic or foreign, in an unbroken chain of
entities beginning with the Company if each of the entities other than the last entity in the unbroken chain beneficially owns, at the time of the determination, securities or interests representing at least 50% of the total combined voting power of
all classes of securities or interests in one of the other entities in such chain. 

  
 17 

 11.42 “Substitute Awards” shall mean Awards granted or Shares issued
by the Company in assumption of, or in substitution or exchange for, awards previously granted, or the right or obligation to make future awards, in each case by a company acquired by the Company or any Subsidiary or with which the Company or any
Subsidiary combines. 
 11.43 “Termination of Service” means the date the Participant ceases to be a Service
Provider. 
 * * * * * 

  
 18

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