Document:

EX-10.2

 Exhibit 10.2 

FUSION PHARMACEUTICALS INC. 

2020 STOCK OPTION AND INCENTIVE PLAN 
  

	SECTION 1.	 GENERAL PURPOSE OF THE PLAN; DEFINITIONS 

The name of the plan is the Fusion Pharmaceuticals Inc. 2020 Stock Option and Incentive Plan (the “Plan”). The purpose of the Plan is
to encourage and enable the officers, employees, Non-Employee Directors and Consultants of Fusion Pharmaceuticals Inc. (the “Company”) and its Affiliates upon whose judgment, initiative and efforts
the Company largely depends for the successful conduct of its business to acquire a proprietary interest in the Company. It is anticipated that providing such persons with a direct stake in the Company’s welfare will assure a closer
identification of their interests with those of the Company and its shareholders, thereby stimulating their efforts on the Company’s behalf and strengthening their desire to remain with the Company. 

The following terms shall be defined as set forth below: 

“Act” means the Securities Act of 1933, as amended, and the rules and regulations thereunder. 

“Administrator” means either the Board or the compensation committee of the Board or a similar committee performing the
functions of the compensation committee and which is comprised of not less than two Non-Employee Directors who are independent. 

“Affiliate” means, at the time of determination, any “parent” or “subsidiary” of the Company as such
terms are defined in Rule 405 of the Act. The Board will have the authority to determine the time or times at which “parent” or “subsidiary” status is determined within the foregoing definition. 

“Award” or “Awards,” except where referring to a particular category of grant under the Plan, shall include
Incentive Stock Options, Non-Qualified Stock Options, Stock Appreciation Rights, Restricted Stock Units, Restricted Stock Awards, Unrestricted Stock Awards, Cash-Based Awards, and Dividend Equivalent Rights.

 “Award Certificate” means a written or electronic document setting forth the terms and provisions applicable to an Award
granted under the Plan. Each Award Certificate is subject to the terms and conditions of the Plan. 
 “Board” means the
Board of Directors of the Company. 
 “Cash-Based Award” means an Award entitling the recipient to receive a
cash-denominated payment. 
 “Cause” means, unless otherwise provided in an employment agreement between the Company or any
Affiliate and a grantee, a determination by the Administrator that the Optionee shall be dismissed as a result of (i) any material breach by the Optionee of any agreement 

 
between the Optionee and the Company or any Affiliate; (ii) the conviction of the Optionee of a crime involving moral turpitude; (iii) any material misconduct or willful and deliberate non-performance (other than by reason of disability) by the Optionee of the Optionee’s duties to the Company; or (iv) any other act or omission (or series of acts or omissions) that would at law permit an
employer to terminate the employment of an employee without notice or payment in lieu thereof. 
 “Code” means the Internal
Revenue Code of 1986, as amended, and any successor Code, and related rules, regulations and interpretations. 

“Consultant” means a consultant or adviser who provides bona fide services to the Company or an Affiliate as an
independent contractor and who qualifies as a consultant or advisor under Instruction A.1.(a)(1) of Form S-8 under the Act. 

“Dividend Equivalent Right” means an Award entitling the grantee to receive credits based on cash dividends that would have
been paid on the Shares specified in the Dividend Equivalent Right (or other award to which it relates) if such Shares had been issued to and held by the grantee. 

“Effective Date” means the date on which the Plan becomes effective as set forth in Section 19. 

“Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations thereunder. 

“Fair Market Value” of the Shares on any given date means the fair market value of the Shares determined in good faith by the
Administrator; provided, however, that if the Shares are listed on the National Association of Securities Dealers Automated Quotation System (“NASDAQ”), NASDAQ Global Market, The New York Stock Exchange or another national securities
exchange or traded on any established market, the determination shall be made by reference to market quotations. If there are no market quotations for such date, the determination shall be made by reference to the last date preceding such date for
which there are market quotations; provided further, however, that if the date for which Fair Market Value is determined is the Registration Date, the Fair Market Value shall be the “Price to the Public” (or equivalent) set forth on the
cover page for the final prospectus relating to the Company’s initial public offering. 
 “Incentive Stock Option”
means any Stock Option designated and qualified as an “incentive stock option” as defined in Section 422 of the Code. 
 “Non-Employee Director” means a member of the Board who is not also an employee of the Company or any Subsidiary. 

“Non-Qualified Stock Option” means any Stock Option that is not an Incentive Stock
Option. 
 “Option” or “Stock Option” means any option to purchase Shares granted pursuant to
Section 5. 

  
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 “Registration Date” means the date upon which the registration statement on
Form S-1 that is filed by the Company with respect to its initial public offering is declared effective by the Securities and Exchange Commission. 

“Restricted Shares” means the Shares underlying a Restricted Stock Award that remain subject to a risk of forfeiture or the
Company’s right of repurchase. 
 “Restricted Stock Award” means an Award of Restricted Shares subject to such
restrictions and conditions as the Administrator may determine at the time of grant. 
 “Restricted Stock Units” means an
Award of stock units subject to such restrictions and conditions as the Administrator may determine at the time of grant. 
 “Sale
Event” shall mean (i) the sale of all or substantially all of the assets of the Company on a consolidated basis to an unrelated person or entity, (ii) a merger, reorganization or consolidation pursuant to which the holders of the
Company’s outstanding voting power and outstanding shares immediately prior to such transaction do not own a majority of the outstanding voting power and outstanding shares or other equity interests of the resulting or successor entity (or its
ultimate parent, if applicable) immediately upon completion of such transaction, (iii) the sale of all of the Shares of the Company to an unrelated person, entity or group thereof acting in concert, or (iv) any other transaction in which
the owners of the Company’s outstanding voting power immediately prior to such transaction do not own at least a majority of the outstanding voting power of the Company or any successor entity immediately upon completion of the transaction
other than as a result of the acquisition of securities directly from the Company. 
 “Sale Price” means the value as
determined by the Administrator of the consideration payable, or otherwise to be received by shareholders, per Share pursuant to a Sale Event. 

“Section 409A” means Section 409A of the Code and the regulations and other guidance promulgated
thereunder. 
 “Service Relationship” means any relationship as an employee, director or Consultant of the Company or any
Affiliate (e.g., a Service Relationship shall be deemed to continue without interruption in the event an individual’s status changes from full-time employee to part-time employee or Consultant). 

“Shares” means the common shares of the Company, subject to adjustments pursuant to Section 3. 

“Stock Appreciation Right” means an Award entitling the recipient to receive Shares(or cash, to the extent explicitly
provided for in the applicable Award Certificate) having a value equal to the excess of the Fair Market Value of the Shares on the date of exercise over the exercise price of the Stock Appreciation Right multiplied by the number of Shares with
respect to which the Stock Appreciation Right shall have been exercised. 
 “Subsidiary” means any corporation or other
entity (other than the Company) in which the Company has at least a 50 percent interest, either directly or indirectly. 

  
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 “Ten Percent Owner” means an employee who owns or is deemed to own (by
reason of the attribution rules of Section 424(d) of the Code) more than 10 percent of the combined voting power of all classes of shares of the Company or any parent or subsidiary corporation. 

“Termination Date” means, subject to any minimum applicable requirements contained in applicable employment standards
legislation, the earlier of: 
 (i) if the grantee’s Service Relationship is terminated by the Company or Affiliate for any reason
(whether lawful or unlawful), the earlier of (a) the date designated, if any, by the Company or Affiliate as the date on which the grantee’s Service Relationship ceases, or (b) the grantee’s last day of actual and active
employment with or service to the Company or Affiliate, whether such day is selected by agreement with the grantee or unilaterally by the Company or Affiliate or otherwise; and, for the avoidance of doubt, in case of either (a) or (b), without
regard to any period of notice of termination, pay in lieu of notice of termination, severance pay or other damages paid or payable to the grantee, under contract or common law, in or in respect of a period which follows the grantee’s last day
of actual and active employment with or service to the Company or Affiliate; 
 (ii) if the grantee dies, the date of death; or 

(iii) if the grantee’s Service Relationship is terminated by the grantee, the date on which the grantee provides notice of resignation to
the Company or Affiliate; or 
 (iv) if the grantee ceases to be eligible to participate in the Plan for any reason not contemplated above,
the date determined by the Company as the date the Service Relationship ends. 
 “Unrestricted Stock Award” means an Award
of Shares free of any restrictions. 
  

	SECTION 2.	 ADMINISTRATION OF PLAN; ADMINISTRATOR AUTHORITY TO SELECT GRANTEES AND DETERMINE AWARDS

 (a) Administration of Plan. The Plan shall be administered by the Administrator. 

(b) Powers of Administrator. The Administrator shall have the power and authority to grant Awards consistent with the terms of the
Plan, including the power and authority: 
 (i) to select the individuals to whom Awards may from time to time be granted; 

(ii) to determine the time or times of grant, and the extent, if any, of Incentive Stock Options,
Non-Qualified Stock Options, Stock Appreciation Rights, Restricted Stock Awards, Restricted Stock Units, Unrestricted Stock Awards, Cash-Based Awards, and Dividend Equivalent Rights, or any combination of the
foregoing, granted to any one or more grantees; 
 (iii) to determine the number of Shares to be covered by any Award; 

  
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 (iv) to determine and modify from time to time the terms and conditions, including
restrictions, not inconsistent with the terms of the Plan, of any Award, which terms and conditions may differ among individual Awards and grantees, and to approve the forms of Award Certificates; 

(v) to accelerate at any time the exercisability or vesting of all or any portion of any Award; 

(vi) subject to the provisions of Section 5(c), to extend at any time the period in which Stock Options may be exercised; and 

(vii) at any time to adopt, alter and repeal such rules, guidelines and practices for administration of the Plan and for its own acts and
proceedings as it shall deem advisable; to interpret the terms and provisions of the Plan and any Award (including related written instruments); to make all determinations it deems advisable for the administration of the Plan; to decide all disputes
arising in connection with the Plan; and to otherwise supervise the administration of the Plan. 
 All decisions and interpretations of the
Administrator shall be binding on all persons, including the Company and Plan grantees. 
 (c) Delegation of Authority to Grant
Awards. Subject to applicable law, the Administrator, in its discretion, may delegate to a committee consisting of one or more officers of the Company including the Chief Executive Officer of the Company all or part of the Administrator’s
authority and duties with respect to the granting of Awards to individuals who are (i) not subject to the reporting and other provisions of Section 16 of the Exchange Act and (ii) not members of the delegated committee. Any such
delegation by the Administrator shall include a limitation as to the amount of Shares underlying Awards that may be granted during the period of the delegation and shall contain guidelines as to the determination of the exercise price and the
vesting criteria. The Administrator may revoke or amend the terms of a delegation at any time but such action shall not invalidate any prior actions of the Administrator’s delegate or delegates that were consistent with the terms of the Plan.

 (d) Award Certificate. Awards under the Plan shall be evidenced by Award Certificates that set forth the terms, conditions and
limitations for each Award which may include, without limitation, the term of an Award and the provisions applicable in the event employment or service terminates. 

(e) Indemnification. Neither the Board nor the Administrator, nor any member of either or any delegate thereof, shall be liable for any
act, omission, interpretation, construction or determination made in good faith in connection with the Plan, and the members of the Board and the Administrator (and any delegate thereof) shall be entitled in all cases to indemnification and
reimbursement by the Company in respect of any claim, loss, damage or expense (including, without limitation, reasonable attorneys’ fees) arising or resulting therefrom to the fullest extent permitted by law and/or under the Company’s
articles or bylaws or any directors’ and officers’ liability insurance coverage which may be in effect from time to time and/or any indemnification agreement between such individual and the Company. 

  
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 (f) Foreign Award Recipients. Notwithstanding any provision of the Plan to the
contrary, in order to comply with the laws in other countries in which the Company and its Subsidiaries operate or have employees or other individuals eligible for Awards, the Administrator, in its sole discretion, shall have the power and authority
to: (i) determine which Subsidiaries shall be covered by the Plan; (ii) determine which individuals outside the United States or Canada are eligible to participate in the Plan; (iii) modify the terms and conditions of any Award
granted to individuals outside the United States or Canada to comply with applicable foreign laws; (iv) establish subplans and modify exercise procedures and other terms and procedures, to the extent the Administrator determines such actions to
be necessary or advisable (and such subplans and/or modifications shall be attached to this Plan as appendices); provided, however, that no such subplans and/or modifications shall increase the share limitations contained in Section 3(a)
hereof; and (v) take any action, before or after an Award is made, that the Administrator determines to be necessary or advisable to obtain approval or comply with any local governmental regulatory exemptions or approvals.
Notwithstanding the foregoing, the Administrator may not take any actions hereunder, and no Awards shall be granted, that would violate the Exchange Act or any other applicable United States securities law, the Code, or any other applicable United
States governing statute or law. 
  

	SECTION 3.	 SHARES ISSUABLE UNDER THE PLAN; MERGERS; SUBSTITUTION 

(a) Shares Issuable. The maximum number of Shares reserved and available for issuance under the Plan shall be 4,273,350 Shares (the
“Initial Limit”), subject to adjustment as provided in this Section 3, plus on January 1, 2021 and each January 1 thereafter, the number of Shares reserved and available for issuance under the Plan shall be cumulatively
increased by 4 percent of the number of Shares issued and outstanding on the immediately preceding December 31 or such lesser amount as determined by the Administrator (the “Annual Increase”). Subject to such overall limitation,
the maximum aggregate number of Shares that may be issued in the form of Incentive Stock Options shall not exceed the Initial Limit cumulatively increased on January 1, 2021 and on each January 1 thereafter by the lesser of the Annual
Increase for such year or 4,273,350 Shares, subject in all cases to adjustment as provided in this Section 3. For purposes of this limitation, the Shares underlying any awards under the Plan and under the Company’s Amended and Restated
2017 Equity Incentive Plan that are forfeited, canceled, held back upon exercise of an Option or settlement of an Award to cover the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of
Shares or otherwise terminated (other than by exercise) shall be added back to the Shares available for issuance under the Plan and, to the extent permitted under Section 422 of the Code and the regulations promulgated thereunder, the Shares
that may be issued as Incentive Stock Options. Subject to such overall limitations, Shares may be issued up to such maximum number pursuant to any type of Award. The Shares available for issuance under the Plan shall be authorized but unissued
Shares. 
 (b) Changes in Shares. Subject to Section 3(c) hereof, if, as a result of any reorganization, recapitalization,
reclassification, stock dividend, stock split, reverse stock split or other similar change in the Company’s capital stock, the outstanding Shares are increased or decreased or are exchanged for a different number or kind of shares or other
securities of the Company, or 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 or other securities, or, if,
as a 

  
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result of any merger or consolidation, sale of all or substantially all of the assets of the Company, the outstanding Shares are converted into or exchanged for securities of the Company or any
successor entity (or a parent or subsidiary thereof), the Administrator shall make an appropriate or proportionate adjustment in (i) the maximum number of shares reserved for issuance under the Plan, including the maximum number of shares that
may be issued in the form of Incentive Stock Options, (ii) the number and kind of shares or other securities subject to any then outstanding Awards under the Plan, (iii) the repurchase price, if any, per share subject to each outstanding
Restricted Stock Award, and (iv) the exercise price for each share subject to any then outstanding Stock Options and Stock Appreciation Rights under the Plan, without changing the aggregate exercise price (i.e., the exercise price multiplied by
the number of shares subject to Stock Options and Stock Appreciation Rights) as to which such Stock Options and Stock Appreciation Rights remain exercisable. The Administrator shall also make equitable or proportionate adjustments in the number of
shares subject to outstanding Awards and the exercise price and the terms of outstanding Awards to take into consideration cash dividends paid other than in the ordinary course or any other extraordinary corporate event. The adjustment by the
Administrator shall be final, binding and conclusive. No fractional Shares shall be issued under the Plan resulting from any such adjustment, but the Administrator in its discretion may make a cash payment in lieu of fractional Shares. 

(c) Mergers and Other Transactions. In the case of and subject to the consummation of a Sale Event, the parties thereto may cause the
assumption or continuation of Awards theretofore granted by the successor entity, or the substitution of such Awards with new Awards of the successor entity or parent thereof, with appropriate adjustment as to the number and kind of Shares and, if
appropriate, the per Share exercise prices, as such parties shall agree. To the extent the parties to such Sale Event do not provide for the assumption, continuation or substitution of Awards, upon the effective time of the Sale Event, the Plan and
all outstanding Awards granted hereunder shall terminate. In such case, except as may be otherwise provided in the relevant Award Certificate, all Options and Stock Appreciation Rights with time-based vesting conditions or restrictions that are not
vested and/or exercisable immediately prior to the effective time of the Sale Event shall become fully vested and exercisable as of the effective time of the Sale Event, all other Awards with time-based vesting, conditions or restrictions shall
become fully vested and nonforfeitable as of the effective time of the Sale Event, and all Awards with conditions and restrictions relating to the attainment of performance goals may become vested and nonforfeitable in connection with a Sale Event
in the Administrator’s discretion or to the extent specified in the relevant Award Certificate. In the event of such termination, (i) the Company shall have the option (in its sole discretion) to make or provide for a payment, in cash or
in kind, to the grantees holding Options and Stock Appreciation Rights, in exchange for the cancellation thereof, in an amount equal to the difference between (A) the Sale Price multiplied by the number of Shares subject to outstanding Options
and Stock Appreciation Rights (to the extent then exercisable at prices not in excess of the Sale Price) and (B) the aggregate exercise price of all such outstanding Options and Stock Appreciation Rights (provided that, in the case of an Option
or Stock Appreciation Right with an exercise price equal to or greater than the Sale Price, such Option or Stock Appreciation Right shall be cancelled for no consideration); or (ii) each grantee shall be permitted, within a specified period of
time prior to the consummation of the Sale Event as determined by the Administrator, to exercise all outstanding Options and Stock Appreciation Rights (to the extent then exercisable) held by such grantee. The Company shall also have the option (in
its sole discretion) to make or provide for a payment, in cash or in kind, to the grantees holding other Awards in an amount equal to the Sale Price multiplied by the number of vested Shares under such Awards. 

  
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 Notwithstanding anything to the contrary herein, in the event a grantee’s Service
Relationship is terminated by the Company or any successor without Cause within one year following the consummation of a Sale Event, any Awards assumed, continued or substituted in a Sale Event which are subject to vesting conditions, the lapse or
achievement of any conditions and/or a right of repurchase in favor of the Company or a successor entity, shall accelerate in full, and any Awards accelerated in such manner with conditions and restrictions relating to the attainment of performance
goals will be deemed achieved at one hundred percent (100%) of target levels. 
 (d) Maximum Awards to Non-Employee Directors. Notwithstanding anything to the contrary in this Plan, the value of all Awards awarded under this Plan and all other cash compensation paid by the Company to any Non-Employee Director in any calendar year for services as a Non-Employee Director shall not exceed (i) $1,000,000 in the first calendar year in which an individual becomes a Non-Employee Director and (ii) $750,000 in any other calendar year. For the purpose of this limitation, the value of any Award shall be its grant date fair value, as determined in accordance with ASC 718 or
successor provision but excluding the impact of estimated forfeitures related to service-based vesting provisions. 
  

	SECTION 4.	 ELIGIBILITY 

Grantees under the Plan will be such employees, Non-Employee Directors or Consultants of the Company
and its Affiliates as are selected from time to time by the Administrator in its sole discretion; provided that Awards may not be granted to employees, Directors or Consultants who are providing services only to any “parent” of the
Company, as such term is defined in Rule 405 of the Act, unless (i) the Shares underlying the Awards is treated as “service recipient stock” under Section 409A or (ii) the Company has determined that such Awards are exempt
from or otherwise comply with Section 409A. 
  

	SECTION 5.	 STOCK OPTIONS 

(a) Award of Stock Options. The Administrator may grant Stock Options under the Plan. Any Stock Option granted under the Plan shall be
in such form as the Administrator may from time to time approve. 
 Stock Options granted under the Plan may be either Incentive Stock
Options or Non-Qualified Stock Options. Incentive Stock Options may be granted only to employees of the Company or any Subsidiary that is a “subsidiary corporation” within the meaning of
Section 424(f) of the Code. To the extent that any Option does not qualify as an Incentive Stock Option, it shall be deemed a Non-Qualified Stock Option. 

Stock Options granted pursuant to this Section 5 shall be subject to the following terms and conditions and shall contain such additional
terms and conditions, not inconsistent with the terms of the Plan, as the Administrator shall deem desirable. If the Administrator so determines, Stock Options may be granted in lieu of cash compensation at the grantee’s election, subject to
such terms and conditions as the Administrator may establish. 

  
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 (b) Exercise Price. The exercise price per Share for the Shares covered by a Stock
Option granted pursuant to this Section 5 shall be determined by the Administrator at the time of grant but shall not be less than 100 percent of the Fair Market Value on the date of grant. In the case of an Incentive Stock Option that is
granted to a Ten Percent Owner, the exercise price of such Incentive Stock Option shall be not less than 110 percent of the Fair Market Value on the grant date. Notwithstanding the foregoing, Stock Options may be granted with an exercise price
per Share that is less than 100 percent of the Fair Market Value on the date of grant (i) pursuant to a transaction described in, and in a manner consistent with, Section 424(a) of the Code, (ii) to individuals who are not
subject to U.S. income tax on the date of grant or (iii) the Stock Option is otherwise compliant with Section 409A. 
 (c)
Option Term. The term of each Stock Option shall be fixed by the Administrator, but no Stock Option shall be exercisable more than ten years after the date the Stock Option is granted. In the case of an Incentive Stock Option that is granted
to a Ten Percent Owner, the term of such Stock Option shall be no more than five years from the date of grant. 
 (d) Exercisability;
Rights as a Shareholder. Stock Options shall become exercisable at such time or times, whether or not in installments, as shall be determined by the Administrator at or after the grant date. The Administrator may at any time accelerate the
exercisability of all or any portion of any Stock Option. A grantee shall not have any rights as a shareholder of the Company until and unless the grantee is issued Shares upon the exercise of a Stock Option and not as to unexercised Stock Options.

 (e) Method of Exercise. Stock Options may be exercised in whole or in part, by giving written or electronic notice of exercise to
the Company (in a form to be provided by the Company), specifying the number of Shares to be purchased. Payment of the purchase price may be made by one or more of the following methods except to the extent otherwise provided in the Award
Certificate: 
 (i) In cash, by certified or bank check or other instrument acceptable to the Administrator; 

(ii) By the grantee delivering to the Company a properly executed exercise notice together 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; provided that in the event the grantee chooses to pay the purchase price as so provided, the grantee and the broker shall comply with such
procedures and enter into such agreements of indemnity and other agreements as the Company shall prescribe as a condition of such payment procedure; or 

(iii) With respect to Stock Options that are not Incentive Stock Options, by a “net exercise” arrangement pursuant to which the
Company will reduce the number of Shares issuable upon exercise by the largest whole number of Shares with a Fair Market Value that does not exceed the aggregate exercise price. 

Payment instruments will be received subject to collection. The transfer to the grantee on the records of the Company or of the transfer agent of the Shares
to be purchased pursuant to the exercise of a Stock Option will be contingent upon receipt from the grantee (or a purchaser 

  
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acting in his stead in accordance with the provisions of the Stock Option) by the Company of the full purchase price for such Shares and the fulfillment of any other requirements contained in the
Award Certificate or applicable provisions of laws (including the satisfaction of any withholding taxes that the Company is obligated to withhold with respect to the grantee). In the event that the Company establishes, for itself or using the
services of a third party, an automated system for the exercise of Stock Options, such as a system using an internet website or interactive voice response, then the paperless exercise of Stock Options may be permitted through the use of such an
automated system. 
 (f) Annual Limit on Incentive Stock Options. To the extent required for “incentive stock option”
treatment under Section 422 of the Code, the aggregate Fair Market Value (determined as of the time of grant) of the Shares with respect to which Incentive Stock Options granted under this Plan and any other plan of the Company or its parent
and subsidiary corporations become exercisable for the first time by an grantee during any calendar year shall not exceed $100,000. To the extent that any Stock Option exceeds this limit, it shall constitute a
Non-Qualified Stock Option. 
  

	SECTION 6.	 STOCK APPRECIATION RIGHTS 

(a) Award of Stock Appreciation Rights. The Administrator may grant Stock Appreciation Rights under the Plan. A Stock Appreciation Right
is an Award entitling the recipient to receive Shares (or cash, to the extent explicitly provided for in the applicable Award Certificate) having a value equal to the excess of the Fair Market Value of a Share on the date of exercise over the
exercise price of the Stock Appreciation Right multiplied by the number of Shares with respect to which the Stock Appreciation Right shall have been exercised. 

(b) Exercise Price of Stock Appreciation Rights. The exercise price of a Stock Appreciation Right shall not be less than
100 percent of the Fair Market Value of the Shares on the date of grant. 
 (c) Grant and Exercise of Stock Appreciation Rights.
Stock Appreciation Rights may be granted by the Administrator independently of any Stock Option granted pursuant to Section 5 of the Plan. 

(d) Terms and Conditions of Stock Appreciation Rights. Stock Appreciation Rights shall be subject to such terms and conditions as shall
be determined on the date of grant by the Administrator. The term of a Stock Appreciation Right may not exceed ten years. The terms and conditions of each such Award shall be determined by the Administrator, and such terms and conditions may differ
among individual Awards and grantees. 
  

	SECTION 7.	 RESTRICTED STOCK AWARDS 

(a) Nature of Restricted Stock Awards. The Administrator may grant Restricted Stock Awards under the Plan. A Restricted Stock Award is
any Award of Restricted Shares subject to such restrictions and conditions as the Administrator may determine at the time of grant. Conditions may be based on continuing employment (or other Service Relationship) and/or achievement of pre-established performance goals and objectives. 

  
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 (b) Rights as a Shareholder. Upon the grant of the Restricted Stock Award and payment
of any applicable purchase price, a grantee shall have the rights of a shareholder with respect to the voting of the Restricted Shares and receipt of dividends; provided that if the lapse of restrictions with respect to the Restricted Stock Award is
tied to the attainment of performance goals, any dividends paid by the Company during the performance period shall accrue and shall not be paid to the grantee until and to the extent the performance goals are met with respect to the Restricted Stock
Award. Unless the Administrator shall otherwise determine, (i) uncertificated Restricted Shares shall be accompanied by a notation on the records of the Company or the transfer agent to the effect that they are subject to forfeiture until such
Restricted Shares are vested as provided in Section 7(d) below, and (ii) certificated Restricted Shares shall remain in the possession of the Company until such Restricted Shares are vested as provided in Section 7(d) below, and the
grantee shall be required, as a condition of the grant, to deliver to the Company such instruments of transfer as the Administrator may prescribe. 

(c) Restrictions. Restricted Shares may not be sold, assigned, transferred, pledged or otherwise encumbered or disposed of except as
specifically provided herein or in the Restricted Stock Award Certificate. Except as may otherwise be provided by the Administrator either in the Award Certificate or, subject to Section 16 below, in writing after the Award is issued, if a
grantee’s employment (or other Service Relationship) with the Company and its Subsidiaries terminates for any reason, any Restricted Shares that have not vested at the time of termination shall automatically and without any requirement of
notice to such grantee from or other action by or on behalf of, the Company be deemed to have been reacquired by the Company at its original purchase price (if any) from such grantee or such grantee’s legal representative simultaneously with
such termination of employment (or other Service Relationship), and thereafter shall cease to represent any ownership of the Company by the grantee or rights of the grantee as a shareholder. Following such deemed reacquisition of Restricted Shares
that are represented by physical certificates, a grantee shall surrender such certificates to the Company upon request without consideration. 

(d) Vesting of Restricted Shares. The Administrator at the time of grant shall specify the date or dates and/or the attainment of pre-established performance goals, objectives and other conditions on which the non-transferability of the Restricted Shares and the Company’s right of repurchase or
forfeiture shall lapse. Subsequent to such date or dates and/or the attainment of such pre-established performance goals, objectives and other conditions, the shares on which all restrictions have lapsed shall
no longer be Restricted Shares and shall be deemed “vested.” 
  

	SECTION 8.	 RESTRICTED STOCK UNITS 

(a) Nature of Restricted Stock Units. The Administrator may grant Restricted Stock Units under the Plan. A Restricted Stock Unit is an
Award of share units that may be settled in Shares (or cash, to the extent explicitly provided for in the Award Certificate) upon the satisfaction of such restrictions and conditions at the time of grant. Conditions may be based on continuing
employment (or other Service Relationship) and/or achievement of pre-established performance goals and objectives. The terms and conditions of each such Award shall be determined by the Administrator, and such
terms and conditions may differ among individual Awards and grantees. Except in the case of Restricted Stock Units with a deferred settlement date that complies with Section 409A, at the end of the vesting period, the Restricted Stock

  
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Units, to the extent vested, shall be settled in the form of Shares. Restricted Stock Units with deferred settlement dates are subject to Section 409A and shall contain such additional terms
and conditions as the Administrator shall determine in its sole discretion in order to comply with the requirements of Section 409A. 

(b) Election to Receive Restricted Stock Units in Lieu of Compensation. The Administrator may, in its sole discretion, permit a grantee
to elect to receive a portion of future cash compensation otherwise due to such grantee in the form of an award of Restricted Stock Units. Any such election shall be made in writing and shall be delivered to the Company no later than the date
specified by the Administrator and in accordance with Section 409A and such other rules and procedures established by the Administrator. Any such future cash compensation that the grantee elects to defer shall be converted to a fixed number of
Restricted Stock Units based on the Fair Market Value of Shares on the date the compensation would otherwise have been paid to the grantee if such payment had not been deferred as provided herein. The Administrator shall have the sole right to
determine whether and under what circumstances to permit such elections and to impose such limitations and other terms and conditions thereon as the Administrator deems appropriate. Any Restricted Stock Units that are elected to be received in lieu
of cash compensation shall be fully vested, unless otherwise provided in the Award Certificate. 
 (c) Rights as a Shareholder. A
grantee shall not have any rights as a shareholder of the Company until and unless the grantee is issued Shares upon settlement of Restricted Stock Units; provided, however, that the grantee may be credited with Dividend Equivalent Rights with
respect to the units underlying his Restricted Stock Units, subject to the provisions of Section 11 and such terms and conditions as the Administrator may determine. 

(d) Termination. Except as may otherwise be provided by the Administrator either in the Award Certificate or, subject to
Section 16 below, in writing after the Award is issued, a grantee’s right in all Restricted Stock Units that have not vested shall automatically terminate on the grantee’s Termination Date upon termination of the grantee’s
employment (or cessation of the grantee’s Service Relationship) with the Company and its Subsidiaries for any reason. 
  

	SECTION 9.	 UNRESTRICTED STOCK AWARDS 

Grant or Sale of Unrestricted Stock. The Administrator may grant (or sell at such purchase price determined by the Administrator) an
Unrestricted Stock Award under the Plan. An Unrestricted Stock Award is an Award pursuant to which the grantee may receive Shares free of any restrictions under the Plan. Unrestricted Stock Awards may be granted in respect of past services or other
valid consideration, or in lieu of cash compensation due to such grantee. 
  

	SECTION 10.	 CASH-BASED AWARDS 

Grant of Cash-Based Awards. The Administrator may grant Cash-Based Awards under the Plan. A Cash-Based Award is an Award that entitles
the grantee to a payment in cash upon the attainment of specified performance goals. The Administrator shall determine the maximum duration of the Cash-Based Award, the amount of cash to which the Cash-Based Award pertains, the conditions upon which
the Cash-Based Award shall become vested or payable, and such 

  
 12 

 
other provisions as the Administrator shall determine. Each Cash-Based Award shall specify a cash-denominated payment amount, formula or payment ranges as determined by the Administrator.
Payment, if any, with respect to a Cash-Based Award shall be made in accordance with the terms of the Award and may be made in cash. 
  

	SECTION 11.	 DIVIDEND EQUIVALENT RIGHTS 

(a) Dividend Equivalent Rights. The Administrator may grant Dividend Equivalent Rights under the Plan. A Dividend Equivalent Right is an
Award entitling the grantee to receive credits based on cash dividends that would have been paid on the Shares specified in the Dividend Equivalent Right (or other Award to which it relates) if such Shares had been issued to the grantee. A Dividend
Equivalent Right may be granted hereunder to any grantee as a component of an award of Restricted Stock Units or as a freestanding award. The terms and conditions of Dividend Equivalent Rights shall be specified in the Award Certificate. Dividend
equivalents credited to the holder of a Dividend Equivalent Right may be paid currently or may be deemed to be reinvested in additional Shares, which may thereafter accrue additional equivalents. Any such reinvestment shall be at Fair Market Value
on the date of reinvestment or such other price as may then apply under a dividend reinvestment plan sponsored by the Company, if any. Dividend Equivalent Rights may be settled in cash or Shares or a combination thereof, in a single installment or
installments. A Dividend Equivalent Right granted as a component of an Award of Restricted Stock Units shall provide that such Dividend Equivalent Right shall be settled only upon settlement or payment of, or lapse of restrictions on, such other
Award, and that such Dividend Equivalent Right shall expire or be forfeited or annulled under the same conditions as such other Award. 

(b) Termination. Except as may otherwise be provided by the Administrator either in the Award Certificate or, subject to
Section 16 below, in writing after the Award is issued, a grantee’s rights in all Dividend Equivalent Rights shall automatically terminate on the grantee’s Termination Date upon termination of employment (or cessation of Service
Relationship) with the Company and its Subsidiaries for any reason. 
  

	SECTION 12.	 TRANSFERABILITY OF AWARDS 

(a) Transferability. Except as provided in Section 12(b) below, during a grantee’s lifetime, his or her Awards shall be
exercisable only by the grantee, or by the grantee’s legal representative or guardian in the event of the grantee’s incapacity. No Awards shall be sold, assigned, transferred or otherwise encumbered or disposed of by a grantee other than
by will or by the laws of descent and distribution or pursuant to a domestic relations order. No Awards shall be subject, in whole or in part, to attachment, execution, or levy of any kind, and any purported transfer in violation hereof shall be
null and void. 
 (b) Administrator Action. Notwithstanding Section 12(a), the Administrator, in its discretion, may provide
either in the Award Certificate regarding a given Award or by subsequent written approval that the grantee (who is an employee or director) may transfer his or her Non-Qualified Stock Options to his or her
immediate family members, to trusts for the benefit of such family members, or to partnerships in which such family members are the only partners, provided that the transferee agrees in writing with the Company to be bound by all of the terms and
conditions of this Plan and the applicable Award. In no event may an Award be transferred by a grantee for value. 

  
 13 

 (c) Family Member. For purposes of Section 12(b), “family member”
shall mean a grantee’s child, stepchild, grandchild, parent, stepparent, grandparent, spouse, former spouse, sibling, niece, nephew, mother-in-law, father-in-law, son-in-law,
daughter-in-law, brother-in-law, or sister-in-law, including adoptive relationships, any person sharing the grantee’s household (other than a tenant of the grantee), a trust in which these persons (or the grantee) have more than
50 percent of the beneficial interest, a foundation in which these persons (or the grantee) control the management of assets, and any other entity in which these persons (or the grantee) own more than 50 percent of the voting interests.

 (d) Designation of Beneficiary. To the extent permitted by the Company, each grantee to whom an Award has been made under the Plan
may designate a beneficiary or beneficiaries to exercise any Award or receive any payment under any Award payable on or after the grantee’s death. Any such designation shall be on a form provided for that purpose by the Administrator and shall
not be effective until received by the Administrator. If no beneficiary has been designated by a deceased grantee, or if the designated beneficiaries have predeceased the grantee, the beneficiary shall be the grantee’s estate. 

 

	SECTION 13.	 TAX WITHHOLDING 

(a) Payment by Grantee. Each grantee shall, no later than the date as of which the value of an Award or of any Shares or other amounts
received thereunder first becomes includable in the gross income of the grantee for Federal or provincial income tax purposes, pay to the Company, or make arrangements satisfactory to the Administrator regarding payment of, any Federal, provincial,
state, or local taxes of any kind required by law to be withheld by the Company with respect to such income. The Company and its Subsidiaries shall, to the extent permitted by law, have the right to deduct any such taxes from any payment of any kind
otherwise due to the grantee. The Company’s obligation to deliver evidence of book entry (or share certificates) to any grantee is subject to and conditioned on tax withholding obligations being satisfied by the grantee. 

(b) Payment in Shares. Except as provided in the Award Certificate, the Administrator may require the Company’s tax withholding
obligation to be satisfied, in whole or in part, by the Company withholding from Shares to be issued pursuant to any Award a number of shares with an aggregate Fair Market Value (as of the date the withholding is effected) that would satisfy the
withholding amount due; provided, however, that the amount withheld does not exceed the maximum statutory tax rate or such lesser amount as is necessary to avoid liability accounting treatment. For purposes of share withholding, the Fair Market
Value of withheld shares shall be determined in the same manner as the value of Shares includible in income of the grantees. The Administrator may also require the Company’s tax withholding obligation to be satisfied, in whole or in part, by an
arrangement whereby a certain number of Shares issued pursuant to any Award are immediately sold and proceeds from such sale are remitted to the Company in an amount that would satisfy the withholding amount due. 

  
 14 

	SECTION 14.	 SECTION 409A AWARDS 

Awards are intended to be exempt from Section 409A to the greatest extent possible and to otherwise comply with Section 409A. The
Plan and all Awards shall be interpreted in accordance with such intent. To the extent that any Award is determined to constitute “nonqualified deferred compensation” within the meaning of Section 409A (a “409A Award”), the
Award shall be subject to such additional rules and requirements as specified by the Administrator from time to time in order to comply with Section 409A. In this regard, if any amount under a 409A Award is payable upon a “separation from
service” (within the meaning of Section 409A) to a grantee who is then considered a “specified employee” (within the meaning of Section 409A), then no such payment shall be made prior to the date that is the earlier of
(i) six months and one day after the grantee’s separation from service, or (ii) the grantee’s death, but only to the extent such delay is necessary to prevent such payment from being subject to interest, penalties and/or
additional tax imposed pursuant to Section 409A. Further, the settlement of any 409A Award may not be accelerated except to the extent permitted by Section 409A. 
  

	SECTION 15.	 TERMINATION OF SERVICE RELATIONSHIP, TRANSFER, LEAVE OF ABSENCE, ETC. 

(a) Termination of Service Relationship. If the grantee’s Service Relationship is with an Affiliate and such Affiliate ceases to be
an Affiliate, the grantee shall be deemed to have terminated his or her Service Relationship for purposes of the Plan. 
 (b) For purposes
of the Plan, the following events shall not be deemed a termination of a Service Relationship: 
 (i) a transfer to the employment of the
Company from an Affiliate or from the Company to an Affiliate, or from one Affiliate to another; or 
 (ii) an approved leave of absence for
military service or sickness, or for any other purpose approved by the Company, if the employee’s right to such leave is protected either by a statute or by contract or under the policy pursuant to which the leave of absence was granted or if
the Administrator otherwise so provides in writing. 
  

	SECTION 16.	 AMENDMENTS AND TERMINATION 

The Board may, at any time, amend or discontinue the Plan and the Administrator may, at any time, amend or cancel any outstanding Award for the
purpose of satisfying changes in law or for any other lawful purpose, but no such action shall materially and adversely affect rights under any outstanding Award without the holder’s consent. Except as provided in Section 3(b) or 3(c),
without prior shareholder approval, in no event may the Administrator exercise its discretion to reduce the exercise price of outstanding Stock Options or Stock Appreciation Rights or effect repricing through cancellation and re-grants or cancellation of Stock Options or Stock Appreciation Rights in exchange for cash or other Awards. To the extent required under the rules of any securities exchange or market system on which the Shares
are listed, to the extent determined by the Administrator to be required by the Code to ensure that Incentive Stock Options granted under the Plan are qualified under Section 422 of the Code, Plan amendments shall be subject to approval by
Company shareholders. Nothing in this Section 16 shall limit the Administrator’s authority to take any action permitted pursuant to Section 3(b) or 3(c). 

  
 15 

	SECTION 17.	 STATUS OF PLAN 

With respect to the portion of any Award that has not been exercised and any payments in cash, Shares or other consideration not received by a
grantee, a grantee shall have no rights greater than those of a general creditor of the Company unless the Administrator shall otherwise expressly determine in connection with any Award or Awards. In its sole discretion, the Administrator may
authorize the creation of trusts or other arrangements to meet the Company’s obligations to deliver Shares or make payments with respect to Awards hereunder, provided that the existence of such trusts or other arrangements is consistent with
the foregoing sentence. 
  

	SECTION 18.	 GENERAL PROVISIONS 

(a) No Distribution. The Administrator may require each person acquiring Shares pursuant to an Award to represent to and agree with the
Company in writing that such person is acquiring the Shares without a view to distribution thereof. 
 (b) Issuance of Shares. To the
extent certificated, share certificates to grantees under this Plan shall be deemed delivered for all purposes when the Company or a stock transfer agent of the Company shall have mailed such certificates in the mail, addressed to the grantee, at
the grantee’s last known address on file with the Company. Uncertificated Shares shall be deemed delivered for all purposes when the Company or a Shares transfer agent of the Company shall have given to the grantee by electronic mail (with
proof of receipt) or by United States mail, addressed to the grantee, at the grantee’s last known address on file with the Company, notice of issuance and recorded the issuance in its records (which may include electronic “book entry”
records). Notwithstanding anything herein to the contrary, the Company shall not be required to issue or deliver any evidence of book entry or certificates evidencing Shares pursuant to the exercise or settlement of any Award, unless and until the
Administrator has determined, with advice of counsel (to the extent the Administrator deems such advice necessary or advisable), that the issuance and delivery is in compliance with all applicable laws, regulations of governmental authorities and,
if applicable, the requirements of any exchange on which the Shares are listed, quoted or traded. Any Shares issued pursuant to the Plan shall be subject to any stop-transfer orders and other restrictions as the Administrator deems necessary or
advisable to comply with federal, state or foreign jurisdiction, securities or other laws, rules and quotation system on which the Shares are listed, quoted or traded. The Administrator may place legends on any share certificate or notations on any
book entry to reference restrictions applicable to the Shares. In addition to the terms and conditions provided herein, the Administrator may require that an individual make such reasonable covenants, agreements, and representations as the
Administrator, in its discretion, deems necessary or advisable in order to comply with any such laws, regulations, or requirements. The Administrator shall have the right to require any individual to comply with any timing or other restrictions with
respect to the settlement or exercise of any Award, including a window-period limitation, as may be imposed in the discretion of the Administrator. 

  
 16 

 (c) Shareholder Rights. Until Shares are deemed delivered in accordance with
Section 18(b), no right to vote or receive dividends or any other rights of a shareholder will exist with respect to Shares to be issued in connection with an Award, notwithstanding the exercise of a Stock Option or any other action by the
grantee with respect to an Award. 
 (d) Other Compensation Arrangements; No Employment Rights. Nothing contained in this Plan shall
prevent the Board from adopting other or additional compensation arrangements, including trusts, and such arrangements may be either generally applicable or applicable only in specific cases. The adoption of this Plan and the grant of Awards do not
confer upon any employee any right to continued employment with the Company or any Affiliate. Except if and as required by applicable employment standards legislation, no grantee will be entitled to any damages or other compensation for any Award
that does not vest or is not awarded or settled due to termination of the grantee’s employment with the Company or Affiliate for any reason. 

(e) Trading Policy Restrictions. Option exercises and other Awards under the Plan shall be subject to the Company’s insider
trading policies and procedures, as in effect from time to time. 
 (f) Clawback Policy. Notwithstanding any other terms of the Plan,
Awards under the Plan may be subject to potential cancellation, recoupment, rescission, payback or other action in accordance with the terms of the Company’s clawback policy, as in effect from time to time, or applicable stock exchange rules.

  

	SECTION 19.	 EFFECTIVE DATE OF PLAN 

This Plan shall become effective upon the date immediately preceding the Registration Date subject to prior shareholder approval in accordance
with applicable state law, the Company’s bylaws and articles of incorporation, and applicable stock exchange rules. No grants of Stock Options and other Awards may be made hereunder after the tenth anniversary of the Effective Date and no
grants of Incentive Stock Options may be made hereunder after the tenth anniversary of the date the Plan is approved by the Board. 
  

	SECTION 20.	 GOVERNING LAW 

This Plan and all Awards and actions taken thereunder shall be governed by, and construed in accordance with, the Province of Ontario as to
matters within the scope thereof, and as to all other matters shall be governed by and construed in accordance with the internal laws of the Province of Ontario, applied without regard to conflict of law principles. 

DATE APPROVED BY BOARD OF DIRECTORS: JUNE 18, 2020 

  
 17 

 INCENTIVE STOCK OPTION AGREEMENT 

UNDER THE FUSION PHARMACEUTICALS, INC. 

2020 STOCK OPTION AND INCENTIVE PLAN 
  

							
	Name of Optionee:	  	  
	  	
				
	No. of Option Shares:	  	  
	  		  	
				
	Option Exercise Price per Share:	  	 $        
	  		  	
		  	[FMV on Grant Date (110% of FMV if a 10% owner)]
				
	Grant Date:	  	  
	  		  	
				
	Expiration Date:	  	  
	  		  	
		  	[up to 10 years (5 if a 10% owner)]

 Pursuant to the Fusion Pharmaceuticals, Inc. 2020 Stock Option and Incentive Plan as amended through the date
hereof (the “Plan”), Fusion Pharmaceuticals, Inc. (the “Company”) hereby grants to the optionee named above (the “Optionee”) an option (the “Stock Option”) to purchase on or prior to the expiration date
specified above (the “Expiration Date”) all or part of the number of common shares (the “Shares”) of the Company specified above at the Option exercise price per Share specified above subject to the terms and conditions set forth
herein and in the Plan. 
 1. Exercisability Schedule. No portion of this Stock Option may be exercised until such portion shall have
become exercisable. Except as set forth below (including pursuant to Section 3 hereof), and subject to the discretion of the Administrator (as defined in Section 2 of the Plan) to accelerate the exercisability schedule hereunder, this
Stock Option shall be exercisable with respect to the following number of Shares (the “Option Shares”) on the dates indicated so long as Optionee remains in a Service Relationship with the Company or an Affiliate on such dates: 

 

							
	Incremental Number of
Option Shares Exercisable*	 	 	Exercisability Date	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 

  

	*	 Max. of $100,000 per yr. 

Once exercisable, this Stock Option shall continue to be exercisable at any time or times prior to the close of business on the Expiration
Date, subject to the provisions hereof and of the Plan. 

 2. Manner of Exercise. 

(a) The Optionee may exercise this Stock Option only in the following manner: from time to time on or prior to the Expiration Date, the
Optionee may give written notice to the Administrator (in a form prescribed by the Company) of his or her election to purchase some or all of the Option Shares purchasable at the time of such notice. This notice shall specify the number of Option
Shares to be purchased. 
 Payment of the exercise price for the Option Shares may be made by one or more of the following methods:
(i) in cash, by certified or bank check or other instrument acceptable to the Administrator; (ii) by the Optionee delivering to the Company a properly executed exercise notice together with irrevocable instructions to a broker to sell
Shares and promptly deliver to the Company all or part of the sale proceeds in cash or a check payable and acceptable to the Company to pay the aggregate exercise price (and, if requested, any applicable Tax Withholdings), provided that in the event
the Optionee chooses to pay the exercise price as so provided, the Optionee and the broker shall comply with such procedures and enter into such agreements of indemnity and other agreements as the Administrator shall prescribe as a condition of such
payment procedure; or (iii) a combination of (i) and (ii) above. Payment instruments will be received subject to collection. 

The transfer to the Optionee on the records of the Company or of the transfer agent of the Option Shares will be contingent upon (i) the
Company’s receipt from the Optionee of the full exercise price and any applicable Tax Withholdings for the Option Shares, as set forth above, (ii) the fulfillment of any other requirements contained herein or in the Plan or in any other
agreement or provision of laws, and (iii) the receipt by the Company of any agreement, statement or other evidence that the Company may require to satisfy itself that the issuance of Shares to be purchased pursuant to the exercise of Stock
Options under the Plan and any subsequent resale of the Shares will be in compliance with applicable laws and regulations. 
 (b) The Shares
purchased upon exercise of this Stock Option shall be transferred to the Optionee on the records of the Company or of the transfer agent upon compliance to the satisfaction of the Administrator with all requirements under applicable laws or
regulations in connection with such transfer and with the requirements hereof and of the Plan. The determination of the Administrator as to such compliance shall be final and binding on the Optionee. The Optionee shall not be deemed to be a
shareholder or have any of the rights as a shareholder of the Company, or have any rights to any Shares subject to this Stock Option unless and until this Stock Option shall have been exercised pursuant to the terms hereof, the Company or the
transfer agent shall have transferred the Shares to the Optionee, and the Optionee’s name shall have been entered as the shareholder of record on the books of the Company. Thereupon, the Optionee shall have full voting, dividend and other
ownership rights with respect to such Shares. 
 (c) The minimum number of Option Shares that may be exercised at any one time shall be 100
Shares, unless the number of Option Shares with respect to which this Stock Option is being exercised is the total number of exercisable Option Shares. 

  
 2 

 (a) Notwithstanding any other provision hereof or of the Plan, no portion of this Stock
Option shall be exercisable after the Expiration Date hereof. 
 3. Termination of Service Relationship. If the Optionee’s
Service Relationship with the Company or an Affiliate (as defined in the Plan) is terminated, the period within which to exercise the Stock Option may be subject to earlier termination as set forth below. 

(a) Termination Due to Death. If the Optionee’s Service Relationship terminates by reason of the Optionee’s death, any
portion of this Stock Option outstanding on such date, to the extent exercisable on the date of death, may thereafter be exercised by the Optionee’s legal representative or legatee for a period of 12 months from the date of death or until the
Expiration Date, if earlier. Any portion of this Stock Option that is not exercisable on the date of death shall terminate immediately and be of no further force or effect. 

(b) Termination Due to Disability. If the Optionee’s Service Relationship terminates by reason of the Optionee’s disability
(as determined by the Administrator), any portion of this Stock Option outstanding on such date, to the extent exercisable on the date of such termination, may thereafter be exercised by the Optionee for a period of 12 months from the date of
disability or until the Expiration Date, if earlier. Any portion of this Stock Option that is not exercisable on the date of disability shall terminate immediately and be of no further force or effect. 

(d) Termination for Cause. If the Optionee’s Service Relationship terminates for Cause, any portion of this Stock Option
outstanding on such date shall terminate immediately and be of no further force and effect. For purposes hereof, “Cause” shall mean, unless otherwise provided in an employment agreement between the Company or any Affiliate and the
Optionee, a determination by the Administrator that the Optionee shall be dismissed as a result of (i) any material breach by the Optionee of any agreement between the Optionee and the Company or any Affiliate; (ii) the conviction of,
indictment for or plea of nolo contendere by the Optionee to a felony or a crime involving moral turpitude; or (iii) any material misconduct or willful and deliberate non-performance (other than by reason
of disability) by the Optionee of the Optionee’s duties to the Company. 
 (c) Other Termination. If the Optionee’s Service
Relationship terminates for any reason other than the Optionee’s death, the Optionee’s disability, or Cause, and unless otherwise determined by the Administrator, any portion of this Stock Option outstanding on such date may be exercised,
to the extent exercisable on the date of termination, for a period of three months from the date of termination or until the Expiration Date, if earlier. Any portion of this Stock Option that is not exercisable on the date of termination shall
terminate immediately and be of no further force or effect. 
 The Administrator’s determination of the reason for termination of the
Optionee’s Service Relationship shall be conclusive and binding on the Optionee and his or her representatives or legatees. 
 4.
Incorporation of Plan. Notwithstanding anything herein to the contrary, this Stock Option shall be subject to and governed by all the terms and conditions of the Plan, 

  
 3 

 
including the powers of the Administrator set forth in Section 2(b) of the Plan. Capitalized terms in this Agreement shall have the meaning specified in the Plan, unless a different meaning
is specified herein. 
 5. Transferability. This Agreement is personal to the Optionee, is
non-assignable and is not transferable in any manner, by operation of law or otherwise, other than by will or the laws of descent and distribution. This Stock Option is exercisable, during the Optionee’s
lifetime, only by the Optionee, and thereafter, only by the Optionee’s legal representative or legatee. 
 6. Status of the Stock
Option. This Stock Option is intended to qualify as an “incentive stock option” under Section 422 of the Internal Revenue Code of 1986, as amended (the “Code”), but the Company does not represent or warrant that this
Stock Option qualifies as such. The Optionee should consult with his or her own tax advisors regarding the tax effects of this Stock Option and the requirements necessary to obtain favorable income tax treatment under Section 422 of the Code,
including, but not limited to, holding period requirements. To the extent any portion of this Stock Option does not so qualify as an “incentive stock option,” such portion shall be deemed to be a
non-qualified stock option. If the Optionee intends to dispose or does dispose (whether by sale, gift, transfer or otherwise) of any Option Shares within the one-year
period beginning on the date after the transfer of such shares to him or her, or within the two-year period beginning on the day after the grant of this Stock Option, he or she will so notify the Company
within 30 days after such disposition. 
 7. Tax Withholding. The Optionee shall, not later than the date as of which the exercise of
this Stock Option becomes a taxable event for Federal income tax purposes, pay to the Company or any Affiliate or make arrangements satisfactory to the Administrator for payment of any Federal, state, and local taxes required by law to be withheld
on account of such taxable event (the “Tax Withholdings”). The Optionee authorizes the Company and/or its Affiliate to cause the required Tax Withholdings to be satisfied, in whole or in part, by (i) withholding from shares to be
issued to the Optionee a number of Shares with an aggregate Fair Market Value that would satisfy the withholding amount due; or (ii) causing its transfer agent to sell from the number of Shares to be issued to the Optionee, the number of Shares
necessary to satisfy the Federal, state and local taxes required by law to be withheld from the Optionee on account of such transfer. 
 8.
No Obligation to Continue Service Relationship. Neither the Company nor any Affiliate is obligated by or as a result of the Plan or this Agreement to continue the Optionee’s Service Relationship and neither the Plan nor this Agreement
shall interfere in any way with the right of the Company or any Affiliate to terminate the Service Relationship of the Optionee at any time. 

9. Integration. This Agreement constitutes the entire agreement between the parties with respect to this Stock Option and supersedes
all prior agreements and discussions between the parties concerning such subject matter. 
 10. Data Privacy Consent. In order to
administer the Plan and this Agreement and to implement or structure future equity grants, the Company, its subsidiaries and affiliates and 

  
 4 

 
certain agents thereof (together, the “Relevant Companies”) may process any and all personal or professional data, including but not limited to Social Security or other identification
number, home address and telephone number, date of birth and other information that is necessary or desirable for the administration of the Plan and/or this Agreement (the “Relevant Information”). By entering into this Agreement, the
Optionee (i) authorizes the Company to collect, process, register and transfer to the Relevant Companies all Relevant Information; (ii) waives any privacy rights the Optionee may have with respect to the Relevant Information;
(iii) authorizes the Relevant Companies to store and transmit such information in electronic form; and (iv) authorizes the transfer of the Relevant Information to any jurisdiction in which the Relevant Companies consider appropriate. The
Optionee shall have access to, and the right to change, the Relevant Information. Relevant Information will only be used in accordance with applicable law. 

11. Notices. Notices hereunder shall be mailed or delivered to the Company at its principal place of business and shall be mailed or
delivered to the Optionee at the address on file with the Company or, in either case, at such other address as one party may subsequently furnish to the other party in writing. 

 

			
	FUSION PHARMACEUTICALS, INC.

 
			
		
	By:	 	  

		 	Title:

 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby agreed to by the undersigned.
Electronic acceptance of this Agreement pursuant to the Company’s instructions to the Optionee (including through an online acceptance process) is acceptable. 
  

									
	Dated:	 	  
	 		 		 	  

		 		 		 		 	Optionee’s Signature
					
		 		 		 		 	Optionee’s name and address:
					
		 		 		 		 	  

					
		 		 		 		 	  

					
		 		 		 		 	  

  
 5 

 NON-QUALIFIED STOCK OPTION AGREEMENT 

FOR UNITED STATES EMPLOYEES 

UNDER THE FUSION PHARMACEUTICALS, INC. 

2020 STOCK OPTION AND INCENTIVE PLAN 
  

							
	Name of Optionee:	  	  
	  	
				
	No. of Option Shares:	  	  
	  		  	
				
	Option Exercise Price per Share:	  	 $        
	  		  	
		  	[FMV on Grant Date]	  		  	
				
	Grant Date:	  	  
	  		  	
				
	Expiration Date:	  	  
	  		  	

 Pursuant to the Fusion Pharmaceuticals, Inc. 2020 Stock Option and Incentive Plan as amended through the date
hereof (the “Plan”), Fusion Pharmaceuticals, Inc. (the “Company”) hereby grants to the optionee named above (the “Optionee”) an option (the “Stock Option”) to purchase on or prior to the expiration date
specified above (the “Expiration Date”) all or part of the number of common shares (the “Shares”) of the Company specified above at the Option exercise price per Share specified above subject to the terms and conditions set forth
herein and in the Plan. This Stock Option is not intended to be an “incentive stock option” under Section 422 of the Internal Revenue Code of 1986, as amended. 

1. Exercisability Schedule. No portion of this Stock Option may be exercised until such portion shall have become exercisable. Except
as set forth below (including pursuant to Section 3 hereof), and subject to the discretion of the Administrator (as defined in Section 2 of the Plan) to accelerate the exercisability schedule hereunder, this Stock Option shall be
exercisable with respect to the following number of Shares (the “Option Shares”) on the dates indicated so long as Optionee remains in a Service Relationship with the Company or an Affiliate on such dates: 

 

							
	Incremental Number of
Option Shares Exercisable	 	 	Exercisability Date	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 

 Once exercisable, this Stock Option shall continue to be exercisable at any time or times
prior to the close of business on the Expiration Date, subject to the provisions hereof and of the Plan. 
 2. Manner of Exercise.

 (a) The Optionee may exercise this Stock Option only in the following manner: from time to time on or prior to the Expiration Date, the
Optionee may give written notice to the Administrator (in a form prescribed by the Company) of his or her election to purchase some or all of the Option Shares purchasable at the time of such notice. This notice shall specify the number of Option
Shares to be purchased. 
 Payment of the exercise price for the Option Shares may be made by one or more of the following methods:
(i) in cash, by certified or bank check or other instrument acceptable to the Administrator; (ii) by the Optionee delivering to the Company a properly executed exercise notice together with irrevocable instructions to a broker to sell
Shares and promptly deliver to the Company all or part of the sale proceeds in cash or a check payable and acceptable to the Company to pay the aggregate exercise price (and, if requested, any applicable Tax Withholdings), provided that in the event
the Optionee chooses to pay the exercise price as so provided, the Optionee and the broker shall comply with such procedures and enter into such agreements of indemnity and other agreements as the Administrator shall prescribe as a condition of such
payment procedure; (iii) subject to the prior consent of the Company, by a “net exercise” arrangement pursuant to which the Optionee will surrender to the Company for cancellation that portion of this Stock Option in respect of the
minimum number of Option Shares with an aggregate Fair Market Value equal to the aggregate exercise price (plus any applicable Tax Withholdings) with any remaining balance of the aggregate Fair Market Value (and or applicable Tax Withholdings) not
satisfied by the surrender of a portion of this Stock Option to be paid by the Optionee in cash; or (iv) a combination of (i), (ii) and (iii) above. Payment instruments will be received subject to collection. 

The transfer to the Optionee on the records of the Company or of the transfer agent of the Option Shares will be contingent upon (i) the
Company’s receipt from the Optionee of the full exercise price and any applicable Tax Withholdings for the Option Shares, as set forth above, (ii) the fulfillment of any other requirements contained herein or in the Plan or in any other
agreement or provision of laws, and (iii) the receipt by the Company of any agreement, statement or other evidence that the Company may require to satisfy itself that the issuance of Shares to be purchased pursuant to the exercise of Stock
Options under the Plan and any subsequent resale of the Shares will be in compliance with applicable laws and regulations. 
 (b) The Shares
purchased upon exercise of this Stock Option shall be transferred to the Optionee on the records of the Company or of the transfer agent upon compliance to the satisfaction of the Administrator with all requirements under applicable laws or
regulations in connection with such transfer and with the requirements hereof and of the Plan. The determination of the Administrator as to such compliance shall be final and binding on the Optionee. The Optionee shall not be deemed to be a
shareholder or have any of the rights as a shareholder of the Company, or have any rights to any Shares subject to this Stock Option unless and until this Stock Option shall have been exercised pursuant to the terms hereof, the Company

  
 2 

 
or the transfer agent shall have transferred the Shares to the Optionee, and the Optionee’s name shall have been entered as the shareholder of record on the books of the Company. Thereupon,
the Optionee shall have full voting, dividend and other ownership rights with respect to such Shares. 
 (c) The minimum number of Option
Shares that may be exercised at any one time shall be 100 Shares, unless the number of Option Shares with respect to which this Stock Option is being exercised is the total number of exercisable Option Shares. 

(d) Notwithstanding any other provision hereof or of the Plan, no portion of this Stock Option shall be exercisable after the Expiration Date
hereof. 
 3. Termination of Service Relationship. If the Optionee’s Service Relationship with the Company or an Affiliate (as
defined in the Plan) is terminated, the period within which to exercise the Stock Option may be subject to earlier termination as set forth below. 

(a) Termination Due to Death. If the Optionee’s Service Relationship terminates by reason of the Optionee’s death, any
portion of this Stock Option outstanding on such date, to the extent exercisable on the date of death, may thereafter be exercised by the Optionee’s legal representative or legatee for a period of 12 months from the date of death or until the
Expiration Date, if earlier. Any portion of this Stock Option that is not exercisable on the date of death shall terminate immediately and be of no further force or effect. 

(b) Termination Due to Disability. If the Optionee’s Service Relationship terminates by reason of the Optionee’s disability
(as determined by the Administrator), any portion of this Stock Option outstanding on such date, to the extent exercisable on the date of such termination, may thereafter be exercised by the Optionee for a period of 12 months from the date of
disability or until the Expiration Date, if earlier. Any portion of this Stock Option that is not exercisable on the date of disability shall terminate immediately and be of no further force or effect. 

(c) Termination for Cause. If the Optionee’s Service Relationship terminates for Cause, any portion of this Stock Option
outstanding on such date shall terminate immediately and be of no further force and effect. For purposes hereof, “Cause” shall mean, unless otherwise provided in an employment agreement between the Company or any Affiliate and the
Optionee, a determination by the Administrator that the Optionee shall be dismissed as a result of (i) any material breach by the Optionee of any agreement between the Optionee and the Company or any Affiliate; (ii) the conviction of,
indictment for or plea of nolo contendere by the Optionee to a felony or a crime involving moral turpitude; or (iii) any material misconduct or willful and deliberate non-performance (other than by reason
of disability) by the Optionee of the Optionee’s duties to the Company. 
 (d) Other Termination. If the Optionee’s Service
Relationship terminates for any reason other than the Optionee’s death, the Optionee’s disability or Cause, and unless otherwise determined by the Administrator, any portion of this Stock Option outstanding on such date may be exercised,
to the extent exercisable on the date of termination, for a period of three months from the date of termination or until the Expiration Date, if earlier. Any portion of this Stock Option that is not exercisable on the date of termination shall
terminate immediately and be of no further force or effect. 

  
 3 

 The Administrator’s determination of the reason for termination of the Optionee’s
Service Relationship shall be conclusive and binding on the Optionee and his or her representatives or legatees. 
 4. Incorporation of
Plan. Notwithstanding anything herein to the contrary, this Stock Option shall be subject to and governed by all the terms and conditions of the Plan, including the powers of the Administrator set forth in Section 2(b) of the Plan.
Capitalized terms in this Agreement shall have the meaning specified in the Plan, unless a different meaning is specified herein. 
 5.
Transferability. This Agreement is personal to the Optionee, is non-assignable and is not transferable in any manner, by operation of law or otherwise, other than by will or the laws of descent and
distribution. This Stock Option is exercisable, during the Optionee’s lifetime, only by the Optionee, and thereafter, only by the Optionee’s legal representative or legatee. 

6. Tax Withholding. The Optionee shall, not later than the date as of which the exercise of this Stock Option becomes a taxable event
for Federal income tax purposes, pay to the Company or any Affiliate or make arrangements satisfactory to the Administrator for payment of any Federal, state, and local taxes required by law to be withheld on account of such taxable event (the
“Tax Withholdings”). The Company or any Affiliate shall have the authority to cause the required Tax Withholdings obligation to be satisfied, in whole or in part, by (i) withholding from Shares to be issued to the Optionee a number of
Shares with an aggregate Fair Market Value that would satisfy the withholding amount due; or (ii) causing its transfer agent to sell from the number of Shares to be issued to the Optionee, the number of Shares necessary to satisfy the Federal,
state and local taxes required by law to be withheld from the Optionee on account of such transfer. 
 7. No Obligation to Continue
Service Relationship. Neither the Company nor any Affiliate is obligated by or as a result of the Plan or this Agreement to continue the Optionee’s Service Relationship and neither the Plan nor this Agreement shall interfere in any way with
the right of the Company or any Affiliate to terminate the Service Relationship of the Optionee at any time. 
 8. Integration. This
Agreement constitutes the entire agreement between the parties with respect to this Stock Option and supersedes all prior agreements and discussions between the parties concerning such subject matter. 

9. Data Privacy Consent. In order to administer the Plan and this Agreement and to implement or structure future equity grants, the
Company, its subsidiaries and affiliates and certain agents thereof (together, the “Relevant Companies”) may process any and all personal or professional data, including but not limited to Social Security or other identification number,
home address and telephone number, date of birth and other information that is necessary or desirable for the administration of the Plan and/or this Agreement (the “Relevant Information”). 

  
 4 

 
By entering into this Agreement, the Optionee (i) authorizes the Company to collect, process, register and transfer to the Relevant Companies all Relevant Information; (ii) waives any
privacy rights the Optionee may have with respect to the Relevant Information; (iii) authorizes the Relevant Companies to store and transmit such information in electronic form; and (iv) authorizes the transfer of the Relevant Information
to any jurisdiction in which the Relevant Companies consider appropriate. The Optionee shall have access to, and the right to change, the Relevant Information. Relevant Information will only be used in accordance with applicable law. 

10. Notices. Notices hereunder shall be mailed or delivered to the Company at its principal place of business and shall be mailed or
delivered to the Optionee at the address on file with the Company or, in either case, at such other address as one party may subsequently furnish to the other party in writing. 

 

			
	FUSION PHARMACEUTICALS, INC.

 
			
		
	By:	 	  

		 	Title:

 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby agreed to by the undersigned.
Electronic acceptance of this Agreement pursuant to the Company’s instructions to the Optionee (including through an online acceptance process) is acceptable. 
  

									
	Dated:	 	  
	 		 		 	  

		 		 		 		 	Optionee’s Signature
					
		 		 		 		 	Optionee’s name and address:
					
		 		 		 		 	  

					
		 		 		 		 	  

					
		 		 		 		 	  

  
 5 

 STOCK OPTION AGREEMENT 

FOR CANADIAN EMPLOYEES 

UNDER THE FUSION PHARMACEUTICALS INC. 

2020 STOCK OPTION AND INCENTIVE PLAN 
  

							
	Name of Optionee:	  	  
	  	
				
	No. of Option Shares:	  	  
	  		  	
				
	Option Exercise Price per Share:	  	 $        
	  		  	
		  	[FMV on Grant Date]	  	
				
	Grant Date:	  	  
	  		  	
				
	Expiration Date:	  	  
	  		  	

 Pursuant to the Fusion Pharmaceuticals Inc. 2020 Stock Option and Incentive Plan as amended through the date
hereof (the “Plan”), Fusion Pharmaceuticals Inc. (the “Company”) hereby grants to the optionee named above (the “Optionee”) an option (the “Stock Option”) to purchase on or prior to the expiration date
specified above (the “Expiration Date”) all or part of the number of common shares (the “Shares”) of the Company specified above at the Option exercise price per Share specified above subject to the terms and conditions set forth
herein and in the Plan. This Stock Option is not intended to be an “incentive stock option” under Section 422 of the Internal Revenue Code of 1986, as amended. 

1. Exercisability Schedule. No portion of this Stock Option may be exercised until such portion shall have become exercisable. Except
as set forth below (including pursuant to Section 3 hereof), and subject to the discretion of the Administrator (as defined in Section 2 of the Plan) to accelerate the exercisability schedule hereunder, this Stock Option shall be
exercisable with respect to the following number of Shares (the “Option Shares”) on the dates indicated so long as Optionee remains actually and actively in a Service Relationship with the Company or Affiliate on such dates: 

 

							
	Incremental Number of
Option Shares Exercisable	 	 	Exercisability Date	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 

 Once exercisable, this Stock Option shall continue to be exercisable at any time or times
prior to the close of business on the Expiration Date, subject to the provisions hereof and of the Plan. 
 2. Manner of Exercise.

 (a) The Optionee may exercise this Stock Option only in the following manner: from time to time on or prior to the Expiration Date, the
Optionee may give written notice to the Administrator (in a form to be provided by the Company) of his or her election to purchase some or all of the Option Shares purchasable at the time of such notice. This notice shall specify the number of
Option Shares to be purchased. 
 Payment of the exercise price for the Option Shares may be made by one or more of the following methods:
(i) in cash, by certified or bank check or other instrument acceptable to the Administrator; (ii) by the Optionee delivering to the Company a properly executed exercise notice together with irrevocable instructions to a broker to sell
Shares and promptly deliver to the Company all or part of the sale proceeds in cash or a check payable and acceptable to the Company to pay the aggregate exercise price (and, if requested, the Tax Withholdings (as defined in Section 6 hereof)),
provided that in the event the Optionee chooses to pay the exercise price as so provided, the Optionee and the broker shall comply with such procedures and enter into such agreements of indemnity and other agreements as the Administrator shall
prescribe as a condition of such payment procedure; (iii) subject to the prior consent of the Company, by a “net exercise” arrangement pursuant to which the Optionee will surrender to the Company for cancellation that portion of this
Stock Option in respect of the minimum number of Option Shares with an aggregate Fair Market Value equal to the aggregate exercise price (plus applicable Tax Withholdings), with any remaining balance of the aggregate Fair Market Value (and/or
applicable Tax Withholdings) not satisfied by the surrender of a portion of this Stock Option to be paid by the Optionee in cash; or (v) a combination of (i), (ii) and (iii) above. Payment instruments will be received subject to
collection. 
 The transfer to the Optionee on the records of the Company or of the transfer agent of the Option Shares will be contingent
upon (i) the Company’s receipt from the Optionee of the full exercise price and any Tax Withholdings for the Option Shares, as set forth above, (ii) the fulfillment of any other requirements contained herein or in the Plan or in any
other agreement or provision of laws, and (iii) the receipt by the Company of any agreement, statement or other evidence that the Company may require to satisfy itself that the issuance of Shares to be purchased pursuant to the exercise of
Stock Options under the Plan and any subsequent resale of the Shares will be in compliance with applicable laws and regulations. 
 (b) The
Shares purchased upon exercise of this Stock Option shall be transferred to the Optionee on the records of the Company or of the transfer agent upon compliance to the satisfaction of the Administrator with all requirements under applicable laws or
regulations in connection with such transfer and with the requirements hereof and of the Plan. The determination of the Administrator as to such compliance shall be final and binding on the Optionee. The Optionee shall not be deemed to be a
shareholder or have any of the rights as a shareholder of the Company, or have any rights to any Shares subject to this Stock Option unless and until this Stock Option shall have been exercised pursuant to the terms hereof, the Company

  
 2 

 
or the transfer agent shall have transferred the Shares to the Optionee, and the Optionee’s name shall have been entered as the shareholder of record on the books of the Company. Thereupon,
the Optionee shall have full voting, dividend and other ownership rights with respect to such Shares. 
 (c) The minimum number of Option
Shares that may be exercised at any one time shall be 100 Shares, unless the number of Option Shares with respect to which this Stock Option is being exercised is the total number of exercisable Option Shares. 

(d) Notwithstanding any other provision hereof or of the Plan, no portion of this Stock Option shall be exercisable after the Expiration Date.

 3. Termination of Service Relationship. If the Optionee’s Service Relationship with the Company or an Affiliate (as defined
in the Plan) is terminated, the period within which to exercise this Stock Option may be subject to earlier termination as set forth below, subject to any minimum applicable requirements contained in applicable employment standards legislation. 

(a) Termination Due to Death. If the Optionee’s Service Relationship terminates by reason of the Optionee’s death, any
portion of this Stock Option outstanding on the Termination Date, to the extent exercisable on the Termination Date, may thereafter be exercised by the Optionee’s legal representative or legatee for a period of 12 months from the Termination
Date or until the Expiration Date, if earlier. Any portion of this Stock Option that is not exercisable on the Termination Date shall terminate immediately and be of no further force or effect. 

(b) Termination Due to Disability. If the Optionee’s Service Relationship terminates by reason of the Optionee’s disability
(as determined by the Administrator), any portion of this Stock Option outstanding on such date, to the extent exercisable on the Termination Date, may thereafter be exercised by the Optionee for a period of 12 months from the Termination Date or
until the Expiration Date, if earlier. Any portion of this Stock Option that is not exercisable on the Termination Date shall terminate immediately and be of no further force or effect. 

(c) Termination for Cause. If the Optionee’s Service Relationship terminates for Cause, any portion of this Stock Option
outstanding on the Termination Date shall terminate immediately and be of no further force and effect. For purposes hereof, “Cause” shall mean, unless otherwise provided in an employment agreement between the Company or any Affiliate and
the Optionee, a determination by the Administrator that the Optionee shall be dismissed as a result of (i) any material breach by the Optionee of any agreement between the Optionee and the Company or any Affiliate; (ii) the conviction of
the Optionee of a crime involving moral turpitude; (iii) any material misconduct or willful and deliberate non-performance (other than by reason of disability) by the Optionee of the Optionee’s
duties to the Company; or (iv) any other act or omission (or series of acts or omissions) that would at law permit an employer to terminate the employment of an employee without notice or payment in lieu thereof. 

(d) Other Termination. If the Optionee’s Service Relationship terminates for any reason other than the Optionee’s death, the
Optionee’s disability or Cause, and unless 

  
 3 

 
otherwise determined by the Administrator, any portion of this Stock Option outstanding on the Termination Date may be exercised, to the extent exercisable on the Termination Date, for a period
of three months from the Termination Date or until the Expiration Date, if earlier. Any portion of this Stock Option that is not exercisable on the Termination Date shall terminate immediately and be of no further force or effect. 

(e) Termination Date. The “Termination Date” for the purposes of this Stock Option means, subject to any minimum applicable
requirements contained in applicable employment standards legislation, the earlier of: 
 (i) if the Optionee’s Service
Relationship is terminated by the Company or Affiliate for any reason (whether lawful or unlawful), the earlier of (a) the date designated, if any, by the Company or Affiliate as the date on which the Optionee’s Service Relationship
ceases, or (b) the Optionee’s last day of actual and active employment with or service to the Company or Affiliate, whether such day is selected by agreement with the Optionee or unilaterally by the Company or Affiliate or otherwise; and,
for the avoidance of doubt, in case of either (a) or (b), without regard to any period of notice of termination, pay in lieu of notice of termination, severance pay or other damages paid or payable to the Optionee, under contract or common law,
in or in respect of a period which follows the Optionee’s last day of actual and active employment with or service to the Company or Affiliate; 

(ii) if the Optionee’s Service Relationship is terminated by the Optionee, the date on which the Optionee provides notice
of resignation to the Company or Affiliate; 
 (iii) if the Optionee dies, the date of death; or 

(iv) if the Optionee ceases to be in a Service Relationship for any reason not contemplated above, the date determined by the
Company as the date the Termination Date. 
 (f) Reason and Consequences of Termination. The Administrator’s determination of
the reason for termination of the Optionee’s Service Relationship shall be conclusive and binding on the Optionee and his or her representatives or legatees. Except if and as required by the minimum applicable requirements of applicable
employment standards legislation, no Optionee will be entitled to any damages or other compensation in respect of any Option that does not become exercisable or is not awarded or exercised due to termination of the Optionee’s Service
Relationship with the Company or Affiliate for any reason. 
 4. Incorporation of Plan. Notwithstanding anything herein to the
contrary, this Stock Option shall be subject to and governed by all the terms and conditions of the Plan, including the powers of the Administrator set forth in Section 2(b) of the Plan. Capitalized terms in this Agreement shall have the
meaning specified in the Plan, unless a different meaning is specified herein. 
 5. Transferability. This Agreement is personal to
the Optionee, is non-assignable and is not transferable in any manner, by operation of law or otherwise, other than by will or the 

  
 4 

 laws of descent and distribution. This Stock Option is exercisable, during the Optionee’s lifetime,
only by the Optionee, and thereafter, only by the Optionee’s legal representative or legatee. 
 6. Tax Withholding. The
Optionee shall, not later than the date as of which the exercise of this Stock Option becomes a taxable or withholding event, as applicable, pay to the Company or make arrangements satisfactory to the Administrator for payment of any applicable
taxes and other withholdings required by law to be withheld on the exercise of this Stock Option (the “Tax Withholdings”). The Optionee authorizes the Company and/or its Affiliate to cause the required Tax Withholdings to be satisfied, in
whole or in part, by withholding from payroll, and any other amounts that may be payable to the Optionee the amount necessary to satisfy the Tax Withholdings on account of such transfer. Alternatively or additionally, and subject to the
Company’s consent, the Optionee may surrender to the Company for cancellation that portion of this Stock Option in respect of the minimum number of Shares with an aggregate Fair Market Value equal to the Tax Withholdings, with any remaining
balance of the Tax Withholdings not satisfied by the surrender of a portion of this Stock Option shall be paid by the Optionee in cash. 

7. No Obligation to Continue Service Relationship. Neither the Company nor any Affiliate is obligated by or as a result of the Plan or
this Agreement to continue the Optionee’s Service Relationship and neither the Plan nor this Agreement shall interfere in any way with the right of the Company or any Affiliate to terminate the Service Relationship of the Optionee at any time.

 8. Integration. This Agreement constitutes the entire agreement between the parties with respect to this Stock Option and
supersedes all prior agreements and discussions between the parties concerning such subject matter. 
 9. Data Privacy Consent. In
order to administer the Plan and this Agreement and to implement or structure future equity grants, the Company, its subsidiaries and affiliates and certain agents thereof (together, the “Relevant Companies”) may process any and all
personal or professional data, including but not limited to social insurance number or other identification number, home address and telephone number, date of birth and other information that is necessary or desirable for the administration of the
Plan and/or this Agreement (the “Relevant Information”). By entering into this Agreement, the Optionee (i) authorizes the Company to collect, process, register and transfer to the Relevant Companies all Relevant Information;
(ii) waives any privacy rights the Optionee may have with respect to the Relevant Information; (iii) authorizes the Relevant Companies to store and transmit such information in electronic form; and (iv) authorizes the transfer of the
Relevant Information to any jurisdiction in which the Relevant Companies consider appropriate. The Optionee shall have access to, and the right to change, the Relevant Information. Relevant Information will only be used in accordance with applicable
law. 
 10. Compliance with Employment Standards. This Agreement shall not be interpreted as in any way waiving or contracting out of
the minimum applicable requirements contained in applicable employment standards legislation and shall be interpreted to achieve compliance with such requirements. It is understood and agreed that all provisions of this Agreement are subject to all
applicable minimum requirements under applicable employment standards legislation and, 

  
 5 

 
in the event that any such minimum requirement provides for superior right or entitlement than provided for under the terms of this Agreement, such right or entitlement shall be provided to the
Optionee, in substitution of the Optionee’s right or entitlement under this Agreement. 
 11. Notices. Notices hereunder shall
be mailed or delivered to the Company at its principal place of business and shall be mailed or delivered to the Optionee at the address on file with the Company or, in either case, at such other address as one party may subsequently furnish to the
other party in writing. 
 12. Language. The parties have expressly required that this Agreement, the Plan and all
documents relating thereto be drafted in the English language. Les parties aux présentes ont expressément exigé que la
présente convention et tous les autres documents qui y sont afférents soient rédigés en langue
anglaise.  
  

			
	FUSION PHARMACEUTICALS INC.

 
			
		
	By:	 	  

		 	Title:

 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby agreed to by the undersigned.
Electronic acceptance of this Agreement pursuant to the Company’s instructions to the Optionee (including through an online acceptance process) is acceptable. 
  

									
	Dated:	 	  
	 		 		 	  

		 		 		 		 	Optionee’s Signature
					
		 		 		 		 	Optionee’s name and address:
					
		 		 		 		 	  

					
		 		 		 		 	  

					
		 		 		 		 	  

  
 6 

 STOCK OPTION AGREEMENT 

FOR NON-EMPLOYEE DIRECTORS 

UNDER THE FUSION PHARMACEUTICALS INC. 

2020 STOCK OPTION AND INCENTIVE PLAN 
  

							
	Name of Optionee:	  	  
	  	
				
	No. of Option Shares:	  	  
	  		  	
				
	Option Exercise Price per Share:	  	 $        
	  		  	
		  	[FMV on Grant Date]	  		  	
				
	Grant Date:	  	  
	  		  	
				
	Expiration Date:	  	  
	  		  	
		  	[No more than 10 years]	  	

 Pursuant to the Fusion Pharmaceuticals Inc. 2020 Stock Option and Incentive Plan as amended through the date
hereof (the “Plan”), Fusion Pharmaceuticals Inc. (the “Company”) hereby grants to the optionee named above (the “Optionee”), who is a Non-Employee Director of the Company but is
not an employee of the Company, an option (the “Stock Option”) to purchase on or prior to the expiration date specified above (the “Expiration Date”) all or part of the number of common shares of the Company (the
“Shares”), of the Company specified above at the Option exercise price per Share specified above subject to the terms and conditions set forth herein and in the Plan. This Stock Option is not intended to be an “incentive stock
option” under Section 422 of the Internal Revenue Code of 1986, as amended. 
 1. Exercisability Schedule. No portion of
this Stock Option may be exercised until such portion shall have become exercisable. Except as set forth below, and subject to the discretion of the Administrator (as defined in Section 2 of the Plan) to accelerate the exercisability schedule
hereunder, this Stock Option shall be exercisable with respect to the following number of Shares (the “Option Shares”) on the dates indicated so long as the Optionee remains in service as a member of the Board on such dates: 

 

							
	Incremental Number of
Option Shares Exercisable	 	 	Exercisability Date	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 

 Once exercisable, this Stock Option shall continue to be exercisable at any time or times
prior to the close of business on the Expiration Date, subject to the provisions hereof and of the Plan. Notwithstanding the forgoing, in the case of a Sale Event in which the Optionee is required to resign from the Board or otherwise not stand for
reelection, all then-unvested Option Shares shall accelerate and become fully vested and exercisable immediately prior to the consummation of a Sale Event, provided that the Optionee has a Service Relationship with the Company at such time. 

2. Manner of Exercise. 

(a) The Optionee may exercise this Stock Option only in the following manner: from time to time on or prior to the Expiration Date, the
Optionee may give written notice to the Administrator (in a form to be provided by the Company) of his or her election to purchase some or all of the Option Shares purchasable at the time of such notice. This notice shall specify the number of
Option Shares to be purchased. 
 Payment of the exercise price for the Option Shares may be made by one or more of the following methods:
(i) in cash, by certified or bank check or other instrument acceptable to the Administrator; (ii) by the Optionee delivering to the Company a properly executed exercise notice together with irrevocable instructions to a broker to sell
Shares and promptly deliver to the Company all or part of the sale proceeds in cash or a check payable and acceptable to the Company to pay the aggregate exercise price (and, if requested, the Tax Withholdings (as defined in Section 6 hereof)),
provided that in the event the Optionee chooses to pay the exercise price as so provided, the Optionee and the broker shall comply with such procedures and enter into such agreements of indemnity and other agreements as the Administrator shall
prescribe as a condition of such payment procedure; (iii) subject to the prior consent of the Company, by a “net exercise” arrangement pursuant to which the Optionee will surrender to the Company for cancellation that portion of this
Stock Option in respect of the minimum number of Option Shares with an aggregate Fair Market Value equal to the aggregate exercise price (plus applicable Tax Withholdings), with any remaining balance of the aggregate Fair Market Value (and/or
applicable Tax Withholdings) not satisfied by the surrender of a portion of this Stock Option to be paid by the Optionee in cash; or (v) a combination of (i), (ii) and (iii) above. Payment instruments will be received subject to
collection. 
 The transfer to the Optionee on the records of the Company or of the transfer agent of the Option Shares will be contingent
upon (i) the Company’s receipt from the Optionee of the full exercise price and any applicable Tax Withholdings for the Option Shares, as set forth above, (ii) the fulfillment of any other requirements contained herein or in the Plan
or in any other agreement or provision of laws, and (iii) the receipt by the Company of any agreement, statement or other evidence that the Company may require to satisfy itself that the issuance of Shares to be purchased pursuant to the
exercise of Stock Options under the Plan and any subsequent resale of the Shares will be in compliance with applicable laws and regulations. 

(b) The Share purchased upon exercise of this Stock Option shall be transferred to the Optionee on the records of the Company or of the
transfer agent upon compliance to the satisfaction of the Administrator with all requirements under applicable laws or regulations in connection with such transfer and with the requirements hereof and of the Plan.

  
 2 

 
The determination of the Administrator as to such compliance shall be final and binding on the Optionee. The Optionee shall not be deemed to be a shareholder or to have any of the rights of as a
shareholder of the Company, or have any rights to any Shares subject to this Stock Option unless and until this Stock Option shall have been exercised pursuant to the terms hereof, the Company or the transfer agent shall have transferred the Shares
to the Optionee, and the Optionee’s name shall have been entered as the shareholder of record on the books of the Company. Thereupon, the Optionee shall have full voting, dividend and other ownership rights with respect to such Shares. 

(c) The minimum number of Option Shares that may be exercised at any one time shall be 100 shares, unless the number of Option Shares with
respect to which this Stock Option is being exercised is the total number of exercisable Option Shares. 
 (d) Notwithstanding any other
provision hereof or of the Plan, no portion of this Stock Option shall be exercisable after the Expiration Date. 
 3. Termination as Non-Employee Director. If the Optionee ceases to be a Non-Employee Director of the Company, the period within which to exercise the Stock Option may be subject to earlier
termination as set forth below. 
 (a) Termination Due to Death. If the Optionee’s service as a
Non-Employee Director terminates by reason of the Optionee’s death, any portion of this Stock Option outstanding on such date, to the extent exercisable on the date of death, may thereafter be exercised
by the Optionee’s legal representative or legatee for a period of 12 months from the date of death or until the Expiration Date, if earlier. Any portion of this Stock Option that is not exercisable on the date of death shall terminate
immediately and be of no further force or effect. 
 (b) Other Termination. If the Optionee ceases to be a Non-Employee Director for any reason other than the Optionee’s death, any portion of this Stock Option outstanding on such date may be exercised, to the extent exercisable on the date the Optionee ceased to be
a Non-Employee Director, for a period of six months from the date the Optionee ceased to be a Non-Employee Director or until the Expiration Date, if earlier. Any portion
of this Stock Option that is not exercisable on the date the Optionee ceases to be a Non-Employee Director shall terminate immediately and be of no further force or effect. 

4. Incorporation of Plan. Notwithstanding anything herein to the contrary, this Stock Option shall be subject to and governed by all
the terms and conditions of the Plan, including the powers of the Administrator set forth in Section 2(b) of the Plan. Capitalized terms in this Agreement shall have the meaning specified in the Plan, unless a different meaning is specified
herein. 
 5. Transferability. This Agreement is personal to the Optionee, is non-assignable
and is not transferable in any manner, by operation of law or otherwise, other than by will or the laws of descent and distribution. This Stock Option is exercisable, during the Optionee’s lifetime, only by the Optionee, and thereafter, only by
the Optionee’s legal representative or legatee. 

  
 3 

 6. Tax Withholding. The Optionee shall, not later than the date as of which the
exercise of this Stock Option becomes a taxable or withholding event, as applicable, pay to the Company or make arrangements satisfactory to the Administrator for payment of any applicable taxes and other withholdings required by law to be withheld
on the exercise of this Stock Option (the “Tax Withholdings”). The Optionee authorizes the Company and/or its Affiliate to cause the required Tax Withholdings to be satisfied, in whole or in part, by withholding from payroll, and any other
amounts that may be payable to the Optionee the amount necessary to satisfy the Tax Withholdings on account of such transfer. Alternatively or additionally, and subject to the Company’s consent, the Optionee may surrender to the Company for
cancellation that portion of this Stock Option in respect of the minimum number of Shares with an aggregate Fair Market Value equal to the Tax Withholdings, with any remaining balance of the Tax Withholdings not satisfied by the surrender of a
portion of this Stock Option shall be paid by the Optionee in cash. 
 7. No Obligation to Continue as a
Non-Employee Director. Neither the Plan nor this Stock Option confers upon the Optionee any rights with respect to continuance as a Non-Employee Director. 

8. Integration. This Agreement constitutes the entire agreement between the parties with respect to this Stock Option and supersedes
all prior agreements and discussions between the parties concerning such subject matter. 
 9. Data Privacy Consent. In order to
administer the Plan and this Agreement and to implement or structure future equity grants, the Company, its subsidiaries and affiliates and certain agents thereof (together, the “Relevant Companies”) may process any and all personal or
professional data, including but not limited to social insurance number or other identification number, home address and telephone number, date of birth and other information that is necessary or desirable for the administration of the Plan and/or
this Agreement (the “Relevant Information”). By entering into this Agreement, the Optionee (i) authorizes the Company to collect, process, register and transfer to the Relevant Companies all Relevant Information; (ii) waives any
privacy rights the Optionee may have with respect to the Relevant Information; (iii) authorizes the Relevant Companies to store and transmit such information in electronic form; and (iv) authorizes the transfer of the Relevant Information
to any jurisdiction in which the Relevant Companies consider appropriate. The Optionee shall have access to, and the right to change, the Relevant Information. Relevant Information will only be used in accordance with applicable law. 

10. Notices. Notices hereunder shall be mailed or delivered to the Company at its principal place of business and shall be mailed or
delivered to the Optionee at the address on file with the Company or, in either case, at such other address as one party may subsequently furnish to the other party in writing. 

11. Language. The parties have expressly required that this Agreement, the Plan and all documents relating thereto be drafted in the
English language. Les parties aux présentes ont expressément exigé que la présente convention et tous les autres documents qui y sont afférents soient rédigés en langue anglaise.

  
 4 

 
			
	FUSION PHARMACEUTICALS INC.

 
			
		
	By:	 	  

		 	Title:

 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby agreed to by the undersigned.
Electronic acceptance of this Agreement pursuant to the Company’s instructions to the Optionee (including through an online acceptance process) is acceptable. 
  

									
	Dated:	 	  
	 		 		 	  

		 		 		 		 	Optionee’s Signature
					
		 		 		 		 	Optionee’s name and address:
					
		 		 		 		 	  

					
		 		 		 		 	  

					
		 		 		 		 	  

  
 5 

 RESTRICTED STOCK UNIT AWARD AGREEMENT 

FOR UNITED STATES EMPLOYEES 

UNDER THE FUSION PHARMACEUTICALS, INC. 

2020 STOCK OPTION AND INCENTIVE PLAN 
  

							
	Name of Grantee:	  	  
	  	
				
	 No. of Restricted Stock Units:
	  	  
	  		  	
				
	Grant Date:	  	  
	  		  	

 Pursuant to the Fusion Pharmaceuticals Inc. 2020 Stock Option and Incentive Plan as amended through the date
hereof (the “Plan”), Fusion Pharmaceuticals Inc. (the “Company”) hereby grants an award of the number of Restricted Stock Units listed above (an “Award”) to the grantee named above (the “Grantee”). Each
Restricted Stock Unit shall relate to one common share (the “Shares”) of the Company. 
 1. Restrictions on Transfer of
Award. This Award may not be sold, transferred, pledged, assigned or otherwise encumbered or disposed of by the Grantee, and any Shares issuable with respect to the Award may not be sold, transferred, pledged, assigned or otherwise encumbered or
disposed of until (i) the Restricted Stock Units have vested as provided in Paragraph 2 of this Agreement and (ii) Shares have been issued to the Grantee in accordance with the terms of the Plan and this Agreement. 

2. Vesting of Restricted Stock Units. The Restricted Stock Units will vest on the vesting date(s) specified in the following table
(each, a “Vesting Date”) so long as the Grantee remains in a Service Relationship with the Company or an Affiliate on such Vesting Date(s). If a series of Vesting Dates is specified in the table, then only the number of Restricted Stock
Units specified in the table below shall vest on the applicable Vesting Date. 
  

							
	Incremental Number of
Restricted Stock Units	 	 	Vesting Date	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 

 The Administrator may at any time accelerate the vesting schedule specified in this Paragraph 2. 

3. Termination of Service Relationship. If the Grantee’s Service Relationship with the Company and its Affiliates terminates for
any reason (including death or disability) prior to the Vesting Date(s) set forth in Paragraph 2 above, any Restricted Stock Units that have not vested as of such date shall automatically and without notice terminate and be forfeited, and neither
the Grantee nor any of his or her successors, heirs, assigns, or personal representatives will thereafter have any further rights or interests in such unvested Restricted Stock Units. 

 4. Issuance of Shares. As soon as practicable following each Vesting Date (but in no
event later than two and one-half months after the end of the year in which the Vesting Date occurs), the Company shall issue to the Grantee the number of Shares equal to the aggregate number of Restricted
Stock Units that have vested pursuant to Paragraph 2 of this Agreement on such date and the Grantee shall thereafter have all the rights of a shareholder of the Company with respect to such shares. 

5. Incorporation of Plan. Notwithstanding anything herein to the contrary, this Agreement shall be subject to and governed by all the
terms and conditions of the Plan, including the powers of the Administrator set forth in Section 2(b) of the Plan. Capitalized terms in this Agreement shall have the meaning specified in the Plan, unless a different meaning is specified herein.

 6. Tax Withholding. The Grantee shall, not later than the date as of which the receipt of this Award becomes a taxable event for
Federal income tax purposes, pay to the Company or any Affiliate or make arrangements satisfactory to the Administrator for payment of any Federal, state, and local taxes required by law to be withheld on account of such taxable event (the “Tax
Withholdings”). The Company or any Affiliate shall have the authority to cause the required Tax Withholdings to be satisfied, in whole or in part, by (i) withholding from Shares to be issued to the Grantee a number of Shares with an
aggregate Fair Market Value that would satisfy the withholding amount due; or (ii) causing its transfer agent to sell from the number of Shares to be issued to the Grantee, the number of Shares necessary to satisfy the Federal, state and local
taxes required by law to be withheld from the Grantee on account of such transfer. 
 7. Section 409A of the Code. This Agreement
shall be interpreted in such a manner that all provisions relating to the settlement of the Award are exempt from the requirements of Section 409A of the Code as “short-term deferrals” as described in Section 409A of the Code.

 8. No Obligation to Continue Service Relationship. Neither the Company nor any Affiliate is obligated by or as a result of the
Plan or this Agreement to continue the Grantee in a Service Relationship and neither the Plan nor this Agreement shall interfere in any way with the right of the Company or any Affiliate to terminate the Service Relationship of the Grantee at any
time. 
 9. Integration. This Agreement constitutes the entire agreement between the parties with respect to this Award and
supersedes all prior agreements and discussions between the parties concerning such subject matter. 
 10. Data Privacy Consent. In
order to administer the Plan and this Agreement and to implement or structure future equity grants, the Company, its subsidiaries and affiliates and certain agents thereof (together, the “Relevant Companies”) may process any and all
personal or professional data, including but not limited to Social Security or other identification number, home address and telephone number, date of birth and other information that is necessary or desirable for the administration of the Plan
and/or this Agreement (the “Relevant Information”). By entering into this Agreement, the Grantee (i) authorizes the Company to collect, process, 

  
 2 

 
register and transfer to the Relevant Companies all Relevant Information; (ii) waives any privacy rights the Grantee may have with respect to the Relevant Information; (iii) authorizes
the Relevant Companies to store and transmit such information in electronic form; and (iv) authorizes the transfer of the Relevant Information to any jurisdiction in which the Relevant Companies consider appropriate. The Grantee shall have
access to, and the right to change, the Relevant Information. Relevant Information will only be used in accordance with applicable law. 

11. Notices. Notices hereunder shall be mailed or delivered to the Company at its principal place of business and shall be mailed or
delivered to the Grantee at the address on file with the Company or, in either case, at such other address as one party may subsequently furnish to the other party in writing. 

 

			
	FUSION PHARMACEUTICALS, INC.

 
			
		
	By:	 	  

		 	Title:

 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby agreed to by the undersigned.
Electronic acceptance of this Agreement pursuant to the Company’s instructions to the Grantee (including through an online acceptance process) is acceptable. 
  

									
	Dated:	 	  
	 		 		 	  

		 		 		 		 	Grantee’s Signature
					
		 		 		 		 	Grantee’s name and address:
					
		 		 		 		 	  

					
		 		 		 		 	  

					
		 		 		 		 	  

  
 3 

 RESTRICTED STOCK UNIT AWARD AGREEMENT 

FOR CANADIAN EMPLOYEES 

UNDER THE FUSION PHARMACEUTICALS INC. 

2020 STOCK OPTION AND INCENTIVE PLAN 
  

							
	 Name of Grantee:
	  	  
	  	
				
	No. of Restricted Stock Units:	  	  
	  		  	
				
	 Grant Date:
	  	  
	  		  	

 Pursuant to the Fusion Pharmaceuticals Inc. 2020 Stock Option and Incentive Plan as amended through the date
hereof (the “Plan”), Fusion Pharmaceuticals Inc. (the “Company”) hereby grants an award of the number of Restricted Stock Units listed above (an “Award”) to the grantee named above (the “Grantee”). Each
Restricted Stock Unit shall relate to one common share (the “Shares”) of the Company. 
 1. Restrictions on Transfer of
Award. This Award may not be sold, transferred, pledged, assigned or otherwise encumbered or disposed of by the Grantee, and any Shares issuable with respect to the Award may not be sold, transferred, pledged, assigned or otherwise encumbered or
disposed of until (i) the Restricted Stock Units have vested as provided in Paragraph 2 of this Agreement and (ii) Shares have been issued to the Grantee in accordance with the terms of the Plan and this Agreement. 

2. Vesting of Restricted Stock Units. The Restricted Stock Units will vest on the vesting date(s) specified in the following table
(each, a “Vesting Date”) so long as the Grantee remains actually and actively in a Service Relationship with the Company or an Affiliate on such Vesting Date(s). If a series of Vesting Dates is specified in the table, then only the number
of Restricted Stock Units specified in the table below shall vest on the applicable Vesting Date. 
  

							
	Incremental Number of
Restricted Stock Units	 	 	Vesting Date	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 

 The Administrator may at any time accelerate the vesting schedule specified in this Paragraph 2. 

3. Termination of Service Relationship. If the Grantee’s Service Relationship with the Company and its Affiliates terminates for
any reason (whether with or without cause, or due to the resignation, death or disability of the Grantee) prior to the Vesting Date(s) set forth in Paragraph 2 above, any Restricted Stock Units that have not vested prior to the Grantee’s
Termination Date (as defined below) shall automatically and without notice terminate and be 

 
forfeited, and neither the Grantee nor any of his or her successors, heirs, assigns, or personal representatives will thereafter have any further rights or interests in such unvested Restricted
Stock Units. Except if and as required by the minimum applicable requirements of applicable employment standards legislation, no Grantee will be entitled to any damages or other compensation in respect of any Restricted Stock Units that do not vest
or in respect of any Shares that are not issued due to termination of the Grantee’s Service Relationship with the Company or its Affiliates for any reason. 

4. Termination Date. The “Termination Date” for the purposes of this Award means, subject to any minimum applicable
requirements contained in applicable employment standards legislation, the earlier of: 
 (a) if the Grantee’s Service Relationship is
terminated by the Company or Affiliate for any reason (whether lawful or unlawful), the earlier of (a) the date designated, if any, by the Company or Affiliate as the date on which the Grantee’s Service Relationship ceases, or (b) the
Grantee’s last day of actual and active employment with or service to the Company or Affiliate, whether such day is selected by agreement with the Grantee or unilaterally by the Company or Affiliate or otherwise; and, for the avoidance of
doubt, in case of either (a) or (b), without regard to any period of notice of termination, pay in lieu of notice of termination, severance pay or other damages paid or payable to the Grantee, under contract or common law, in or in respect of a
period which follows the Grantee’s last day of actual and active employment with or service to the Company or Affiliate; 
 (b) if the
Grantee’s Service Relationship is terminated by the Grantee, the date on which the Grantee provides notice of resignation to the Company or Affiliate; 

(c) if the Grantee dies, the date of death; or 

(d) if the Grantee ceases to be in a Service Relationship for any reason not contemplated above, the date determined by the Company as the
date the Termination Date. 
 5. Issuance of Shares. As soon as practicable following each Vesting Date (but in no event later than
two and one-half months after the end of the year in which the Vesting Date occurs), the Company shall issue to the Grantee the number of Shares equal to the aggregate number of Restricted Stock Units that
have vested pursuant to Paragraph 2 of this Agreement on such date and the Grantee shall thereafter have all the rights of a shareholder of the Company with respect to such shares. 

6. Incorporation of Plan. Notwithstanding anything herein to the contrary, this Agreement shall be subject to and governed by all the
terms and conditions of the Plan, including the powers of the Administrator set forth in Section 2(b) of the Plan. Capitalized terms in this Agreement shall have the meaning specified in the Plan, unless a different meaning is specified herein.

 7. Tax Withholding. The Grantee shall, not later than the date as of which the receipt of this Award becomes a taxable or
withholding event, as applicable, pay to the Company or make arrangements satisfactory to the Administrator for payment of any applicable taxes and other withholdings required by law to be withheld on account of such taxable or withholding event
(the “Tax Withholdings”). The Company shall have the authority to cause the required 

  
 2 

 
Tax Withholdings to be satisfied, in whole or in part, by (i) withholding from payroll any other amounts that may be payable to the Grantee the amount necessary to satisfy the Tax
Withholdings; or (ii) allowing the Grantee to surrender to the Company for cancellation that portion of this Award in respect of the minimum number of Shares with an aggregate Fair Market Value equal to the Tax Withholdings, with any remaining
balance of the Tax Withholdings not satisfied by the surrender of a portion of this Award shall be paid by the Grantee in cash. 
 8.
Section 409A of the Code. This Agreement shall be interpreted in such a manner that all provisions relating to the settlement of the Award are exempt from the requirements of Section 409A of the Code as “short-term deferrals”
as described in Section 409A of the Code. 
 9. No Obligation to Continue Service Relationship. Neither the Company nor any
Affiliate is obligated by or as a result of the Plan or this Agreement to continue the Grantee’s Service Relationship and neither the Plan nor this Agreement shall interfere in any way with the right of the Company or any Affiliate to terminate
the Service Relationship of the Grantee at any time. 
 10. Integration. This Agreement constitutes the entire agreement between the
parties with respect to this Award and supersedes all prior agreements and discussions between the parties concerning such subject matter. 

11. Data Privacy Consent. In order to administer the Plan and this Agreement and to implement or structure future equity grants, the
Company, its subsidiaries and affiliates and certain agents thereof (together, the “Relevant Companies”) may process any and all personal or professional data, including but not limited to social insurance number or other identification
number, home address and telephone number, date of birth and other information that is necessary or desirable for the administration of the Plan and/or this Agreement (the “Relevant Information”). By entering into this Agreement, the
Grantee (i) authorizes the Company to collect, process, register and transfer to the Relevant Companies all Relevant Information; (ii) waives any privacy rights the Grantee may have with respect to the Relevant Information;
(iii) authorizes the Relevant Companies to store and transmit such information in electronic form; and (iv) authorizes the transfer of the Relevant Information to any jurisdiction in which the Relevant Companies consider appropriate. The
Grantee shall have access to, and the right to change, the Relevant Information. Relevant Information will only be used in accordance with applicable law. 

12. Compliance with Employment Standards. This Agreement shall not be interpreted as in any way waiving or contracting out of the
minimum applicable requirements contained in applicable employment standards legislation and shall be interpreted to achieve compliance with such requirements. It is understood and agreed that all provisions of this Agreement are subject to all
applicable minimum requirements under applicable employment standards legislation and, in the event that any such minimum requirement provides for superior right or entitlement than provided for under the terms of this Agreement, such right or
entitlement shall be provided to the Grantee, in substitution of the Grantee’s right or entitlement under this Agreement. 
 13.
Notices. Notices hereunder shall be mailed or delivered to the Company at its principal place of business and shall be mailed or delivered to the Grantee at the address on file with the Company or, in either case, at such other address as one
party may subsequently furnish to the other party in writing. 

  
 3 

 14. Language. The parties have expressly required that this Agreement, the
Plan and all documents relating thereto be drafted in the English language. Les parties aux présentes ont expressément exigé que la présente convention et tous les autres documents qui y sont afférents
soient rédigés en langue anglaise. 
  

			
	FUSION PHARMACEUTICALS INC.

 
			
		
	By:	 	  

		 	Title:

 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby agreed to by the undersigned.
Electronic acceptance of this Agreement pursuant to the Company’s instructions to the Grantee (including through an online acceptance process) is acceptable. 
  

									
	Dated:	 	  
	 		 		 	  

		 		 		 		 	Grantee’s Signature
					
		 		 		 		 	Grantee’s name and address:
					
		 		 		 		 	  

					
		 		 		 		 	  

					
		 		 		 		 	  

  
 4 

 RESTRICTED STOCK UNIT AWARD AGREEMENT 

FOR NON-EMPLOYEE DIRECTORS 

UNDER THE FUSION PHARMACEUTICALS INC. 

2020 STOCK OPTION AND INCENTIVE PLAN 
  

							
	 Name of Grantee:
	  	  
	  	
				
	No. of Restricted Stock Units:	  	  
	  		  	
				
	 Grant Date:
	  	  
	  		  	

 Pursuant to the Fusion Pharmaceuticals Inc. 2020 Stock Option and Incentive Plan as amended through the date
hereof (the “Plan”), Fusion Pharmaceuticals Inc. (the “Company”) hereby grants an award of the number of Restricted Stock Units listed above (an “Award”) to the grantee named above (the “Grantee”). Each
Restricted Stock Unit shall relate to one common share (the “Shares”) of the Company. 
 1. Restrictions on Transfer of
Award. This Award may not be sold, transferred, pledged, assigned or otherwise encumbered or disposed of by the Grantee, and any Shares issuable with respect to the Award may not be sold, transferred, pledged, assigned or otherwise encumbered or
disposed of until (i) the Restricted Stock Units have vested as provided in Paragraph 2 of this Agreement and (ii) Shares have been issued to the Grantee in accordance with the terms of the Plan and this Agreement. 

2. Vesting of Restricted Stock Units. The Restricted Stock Units will vest on the vesting date(s) specified in the following table
(each, a “Vesting Date”) so long as the Grantee remains in service as a member of the Board on such Vesting Date(s). If a series of Vesting Dates is specified in the table, then only the number of Restricted Stock Units specified in the
table below shall vest on the applicable Vesting Date. 
  

							
	Incremental Number of
Restricted Stock Units	 	 	Vesting Date	 
		
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 
	 	                     (    	%) 	 	 	            	 

 In the event of a Sale Event in which the Director is asked to resign or otherwise not stand for reelection,
100% of the Restricted Stock Units shall become vested immediately prior to the consummation of such Sale Event. The Administrator may at any time accelerate the vesting schedule specified in this Paragraph 2. 

3. Termination of Service as a Non-Employee Director. If the Grantee’s service with the
Company and its Subsidiaries as a member of the Board terminates for any reason (including death or disability) prior to the applicable Vesting Date(s) set forth in Paragraph 2 

 
above, any Restricted Stock Units that have not vested as of such date shall automatically and without notice terminate and be forfeited, and neither the Grantee nor any of his or her successors,
heirs, assigns, or personal representatives will thereafter have any further rights or interests in such unvested Restricted Stock Units. 

4. Issuance of Shares. As soon as practicable following each Vesting Date (but in no event later than two and one-half months after the end of the year in which the Vesting Date occurs), the Company shall issue to the Grantee the number of Shares equal to the aggregate number of Restricted Stock Units that have vested
pursuant to Paragraph 2 of this Agreement on such date and the Grantee shall thereafter have all the rights of a shareholder of the Company with respect to such shares. 

5. Incorporation of Plan. Notwithstanding anything herein to the contrary, this Agreement shall be subject to and governed by all the
terms and conditions of the Plan, including the powers of the Administrator set forth in Section 2(b) of the Plan. Capitalized terms in this Agreement shall have the meaning specified in the Plan, unless a different meaning is specified herein.

 6. Section 409A of the Code. This Agreement shall be interpreted in such a manner that all provisions relating to the settlement
of the Award are exempt from the requirements of Section 409A of the Code as “short-term deferrals” as described in Section 409A of the Code. 

7. No Obligation to Continue as a Non-Employee Director. Neither the Plan nor this Award
confers upon the Grantee any rights with respect to continuance as a Non-Employee Director. 
 8.
Integration. This Agreement constitutes the entire agreement between the parties with respect to this Award and supersedes all prior agreements and discussions between the parties concerning such subject matter. 

9. Tax Withholding. The Grantee shall, not later than the date as of which the receipt of this Award becomes a taxable or withholding
event, as applicable, pay to the Company or make arrangements satisfactory to the Administrator for payment of any applicable taxes and other withholdings required by law to be withheld on account of such taxable or withholding event (the “Tax
Withholdings”). The Company shall have the authority to cause the required Tax Withholdings to be satisfied, in whole or in part, by (i) withholding from payroll any other amounts that may be payable to the Grantee the amount necessary to
satisfy the Tax Withholdings; or (ii) allowing the Grantee to surrender to the Company for cancellation that portion of this Award in respect of the minimum number of Shares with an aggregate Fair Market Value equal to the Tax Withholdings,
with any remaining balance of the Tax Withholdings not satisfied by the surrender of a portion of this Award shall be paid by the Grantee in cash. 

10. Data Privacy Consent. In order to administer the Plan and this Agreement and to implement or structure future equity grants, the
Company, its subsidiaries and affiliates and certain agents thereof (together, the “Relevant Companies”) may process any and all personal or professional data, including but not limited to social insurance number, social security number or
other identification number, home address and telephone number, date of birth and other 

  
 2 

 
information that is necessary or desirable for the administration of the Plan and/or this Agreement (the “Relevant Information”). By entering into this Agreement, the Grantee
(i) authorizes the Company to collect, process, register and transfer to the Relevant Companies all Relevant Information; (ii) waives any privacy rights the Grantee may have with respect to the Relevant Information; (iii) authorizes
the Relevant Companies to store and transmit such information in electronic form; and (iv) authorizes the transfer of the Relevant Information to any jurisdiction in which the Relevant Companies consider appropriate. The Grantee shall have
access to, and the right to change, the Relevant Information. Relevant Information will only be used in accordance with applicable law. 

11. Notices. Notices hereunder shall be mailed or delivered to the Company at its principal place of business and shall be mailed or
delivered to the Grantee at the address on file with the Company or, in either case, at such other address as one party may subsequently furnish to the other party in writing. 

12. Language. The parties have expressly required that this Agreement, the Plan and all documents relating thereto be drafted in the
English language. Les parties aux présentes ont expressément exigé que la présente convention et tous les autres documents qui y sont afférents soient rédigés en langue
anglaise. 
  

			
	FUSION PHARMACEUTICALS INC.

 
			
		
	By:	 	  

		 	Title:

 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby agreed to by the undersigned.
Electronic acceptance of this Agreement pursuant to the Company’s instructions to the Grantee (including through an online acceptance process) is acceptable. 
  

									
	Dated:	 	  
	 		 		 	  

		 		 		 		 	Grantee’s Signature
					
		 		 		 		 	Grantee’s name and address:
					
		 		 		 		 	  

					
		 		 		 		 	  

					
		 		 		 		 	  

  
 3EX-10.3

 Exhibit 10.3 

FUSION PHARMACEUTICALS INC. 

SENIOR EXECUTIVE CASH INCENTIVE BONUS PLAN 
  

	1.	 Purpose 

This Senior Executive Cash Incentive Bonus Plan (the “Incentive Plan”) is intended to provide an incentive for superior work and to
motivate eligible executives of Fusion Pharmaceuticals Inc. (the “Company”) and its subsidiaries toward even higher achievement and business results, to tie their goals and interests to those of the Company and its shareholders and to
enable the Company and its subsidiaries to attract and retain highly qualified executives. The Incentive Plan is for the benefit of Covered Executives (as defined below). 
  

	2.	 Covered Executives 

From time to time, the Compensation Committee of the Board of Directors of the Company (the “Compensation Committee”) may select
certain key executives (the “Covered Executives”) to be eligible to receive bonuses hereunder. Participation in the Incentive Plan does not change the “at will” nature of a Covered Executive’s employment with the Company or
otherwise alter any written agreement between the Covered Executive and the Company or between the Covered Executive and any subsidiary of the Company (each, an “Employment Agreement”). 

 

	3.	 Administration 

The Compensation Committee shall have the sole discretion and authority to administer and interpret the Incentive Plan. 

 

	4.	 Bonus Determinations 

(a) Corporate Performance Goals. A Covered Executive may receive a bonus payment under the Incentive Plan based upon the attainment of
one or more performance objectives that are established by the Compensation Committee and relate to financial or operational metrics with respect to the Company or any of its subsidiaries (the “Corporate Performance Goals”), including
without limitation the following: achievement of specified research and development, publication, clinical and/or regulatory milestones; cash flow (including, but not limited to, operating cash flow and adjusted free cash flow); earnings before
interest, taxes, depreciation and amortization; net income (loss) (either before or after interest, taxes, depreciation and/or amortization); changes in the market price of our common shares; economic value-added; acquisitions or strategic
transactions, including licenses, collaborations, joint ventures or promotion arrangements; financing or other capital raising transactions; operating income (loss); return on capital, assets, equity, or investment; total shareholder returns;
productivity; expense efficiency; margins; operating efficiency; working capital; earnings (loss) per share of our common shares; sales or market shares; revenue; corporate revenue; number of prescriptions or prescribing physicians; coverage
decisions; leadership development, employee retention, and recruiting and other human resources matters; operating income and/or net annual recurring revenue, any of which may be (A) measured in absolute terms or compared to any

 
incremental increase, (B) measured in terms of growth, (C) compared to another company or companies or to results of a peer group, (D) measured against the market as a whole and/or
as compared to applicable market indices and/or (E) measured on a pre-tax or post-tax basis (if applicable). Further, any Corporate Performance Goals may be used to
measure the performance of the Company and its subsidiaries as a whole or a business unit or other segment of the Company or any subsidiary, or one or more product lines or specific markets. The Corporate Performance Goals may differ from
Covered Executive to Covered Executive. 
 (b) Calculation of Corporate Performance Goals. At the beginning of each applicable
performance period, the Compensation Committee will determine whether any significant element(s) will be included in or excluded from the calculation of any Corporate Performance Goal with respect to any Covered Executive. In all other
respects, Corporate Performance Goals will be calculated in accordance with the Company’s financial statements, generally accepted accounting principles, or under a methodology established by the Compensation Committee at the beginning of the
performance period and which is consistently applied with respect to a Corporate Performance Goal in the relevant performance period. 
 (c)
Target; Minimum; Maximum. Each Corporate Performance Goal shall have a “target” (for example, 100 percent attainment of the Corporate Performance Goal) and may also have a “minimum” hurdle and/or a “maximum”
amount. 
 (d) Bonus Requirements; Individual Goals. Except as otherwise set forth in this Section 4(d): (i) any bonuses paid to
Covered Executives under the Incentive Plan shall be based upon objectively determinable bonus formulas that tie such bonuses to one or more performance targets relating to the Corporate Performance Goals, (ii) bonus formulas for Covered
Executives shall be adopted in each performance period by the Compensation Committee and communicated to each Covered Executive at the beginning of each performance period and (iii) no bonuses shall be paid to Covered Executives unless and
until the Compensation Committee makes a determination with respect to the attainment of the performance targets relating to the Corporate Performance Goals. Notwithstanding the foregoing, the Compensation Committee may adjust bonuses payable under
the Incentive Plan based on achievement of one or more individual performance objectives or pay bonuses (including, without limitation, discretionary bonuses) to Covered Executives under the Incentive Plan based on individual performance goals
and/or upon such other terms and conditions as the Compensation Committee may in its discretion determine. 
 (e) Individual Target
Bonuses. The Compensation Committee shall establish a target bonus opportunity for each Covered Executive for each performance period. For each Covered Executive, the Compensation Committee shall have the authority to apportion the target award
so that a portion of the target award shall be tied to attainment of Corporate Performance Goals and a portion of the target award shall be tied to attainment of individual performance objectives. 

(f) Employment Requirement. A bonus is not earned, accrued or payable until the payout date of such bonus. Subject to any additional
terms contained in an Employment Agreement, the payment of a bonus to a Covered Executive with respect to a performance period shall be conditioned upon the Covered Executive Actively Performing Services (as defined below) for the Company or one of
its subsidiaries on the bonus payment date. If a Covered Executive commences employment after the first day of a Performance Period, the 

  
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Compensation Committee may, but shall not be required to, pro rate the bonus based on the number of days the Covered Executive was Actively Performing Services during the performance period. 

(g) If a Covered Executive gives notice of resignation or retirement, the Covered Executive will be deemed to have ceased to be “Actively
Performing Services” for the Company or applicable subsidiary on the date that the Covered Executive gives notice of resignation or retirement to the Company or applicable subsidiary. If the Covered Executive’s employment is terminated by
the Company or applicable subsidiary, regardless of whether the termination is with or without cause, or lawful or unlawful, the Covered Executive will cease to be Actively Performing Services on the date specified by the Company or its subsidiary
in its written notice of termination to the Covered Executive as being the Covered Executive’s termination date, without regard to any notice or pay in lieu of notice to which the Covered Executive might then be entitled, except as may be
expressly required by any minimum applicable requirements contained in applicable employment standards legislation (such requirements, “ESA”). For the avoidance of doubt, and except as may be expressly required by ESA, the Covered
Executive will not be considered to be Actively Performing Services for the Company or any of its subsidiaries during any period during which the Covered Executive receives, or claims to be entitled to, any compensatory payments in lieu of notice of
termination, and the Covered Executive is not entitled to any damages for any bonus (or portion thereof) in respect of such period whether pursuant to common law or contract. 
  

	5.	 Timing of Payment 

(a) With respect to Corporate Performance Goals established and measured on a basis more frequently than annually (e.g., quarterly or
semi-annually), the Corporate Performance Goals will be measured at the end of each performance period after the Company’s financial reports with respect to such period(s), to the extent relevant to the performance period, have been made
available to the Compensation Committee. If the Corporate Performance Goals and/or individual goals for such period are met, payments will be made as soon as practicable following the end of such period, but not later 74 days after the end of the
fiscal year in which such performance period ends. 
 (b) With respect to Corporate Performance Goals established and measured on an annual
or multi-year basis, Corporate Performance Goals will be measured as of the end of each such performance period (e.g., the end of each fiscal year) after the Company’s financial reports with respect to such period(s), to the extent relevant to
the performance period, have been made available to the Compensation Committee. If the Corporate Performance Goals and/or individual goals for any such period are met, bonus payments will be made as soon as practicable, but not later than 74 days
after the end of the relevant fiscal year. 
 (c) For the avoidance of doubt, bonuses earned at any time in a fiscal year must be paid no
later than 74 days after the last day of such fiscal year. 

  
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	6.	 Amendment and Termination 

The Company reserves the right to amend or terminate the Incentive Plan at any time (with or without replacing it with a comparable plan) in
its sole discretion. 
  

	7.	 Governing Law 

The Incentive Plan shall be governed by, and construed in accordance with, the Province of Ontario as to matters within the scope thereof, and
as to all other matters shall be governed by and construed in accordance with the internal laws of the Province of Ontario, applied without regard to conflict of law principles. 

 

	8.	 Effect on Employment 

Neither participation in the Incentive Plan nor payment of a bonus hereunder confers upon any employee any right to participate in the
Incentive Plan in the future. Except if and as required by ESA, no Covered Executive will be entitled to any damages or other compensation for any bonus that is not paid due to termination of the Covered Executive’s employment with the Company
or any subsidiary for any reason. 
  

	9.	 Language 

The parties agree that the Incentive Plan as well as all documents and notices pursuant hereto or relating directly or indirectly hereto be
drawn up in English. Les parties reconnaissent avoir accepté que la présente convention ainsi que tout document exécuté et avis donné directement ou indirectement à la suite ou relativement à la
présente convention soient rédigés en anglais. 
 Date Approved: June 18, 2020 

  
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