Document:

EX-10.6

 Exhibit 10.6 

FUSION PHARMACEUTICALS INC. 

[FORM OF] DIRECTOR INDEMNIFICATION AGREEMENT 

This Indemnification Agreement (“Agreement”) is made as of [Date] by and between Fusion Pharmaceuticals Inc. (the
“Company”), a corporation existing under the Canada Business Corporations Act (the “CBCA”), and [Director Name] (“Indemnitee”). 

RECITALS 
 WHEREAS, the Company
desires to attract and retain the services of highly qualified individuals, such as Indemnitee, to serve the Company; 
 WHEREAS, in order
to induce Indemnitee to provide or continue to provide services to the Company, the Company wishes to provide for the indemnification of, and advancement of expenses to, Indemnitee to the maximum extent permitted by law; 

WHEREAS, the bylaws (as amended and in effect from time to time, the “Bylaws”) of the Company require indemnification of the
officers and directors of the Company, and Indemnitee may also be entitled to indemnification pursuant to the CBCA; 
 WHEREAS, the Company
and Indemnitee wish to supplement the indemnification provisions in the Bylaws and the CBCA; 
 WHEREAS, the Board of Directors of the
Company (the “Board”) has determined that the increased difficulty in attracting and retaining highly qualified persons such as Indemnitee is detrimental to the best interests of the Company; 

WHEREAS, it is reasonable and prudent for the Company contractually to obligate itself to indemnify, and to advance expenses on behalf of,
such persons to the fullest extent permitted by applicable law, regardless of any amendment or revocation of the Bylaws, so that they will serve or continue to serve the Company free from undue concern that they will not be so indemnified; 

WHEREAS, this Agreement is a supplement to and in furtherance of the indemnification provided in the Bylaws and any resolutions adopted
pursuant thereto, and shall not be deemed a substitute therefor, nor to diminish or abrogate any rights of Indemnitee thereunder; and 

[WHEREAS, Indemnitee has certain rights to indemnification and/or insurance provided by
[                    ]
(“[                    ]”) which Indemnitee and
[                    ] intend to be secondary to the primary obligation of the Company to indemnify Indemnitee as provided in this Agreement, with
the Company’s acknowledgment and agreement to the foregoing being a material condition to Indemnitee’s willingness to serve or continue to serve on the Board.] 

  
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 NOW, THEREFORE, in consideration of the premises and the covenants contained herein, the
Company and Indemnitee do hereby covenant and agree as follows: 
 Section 1.     Services to the Company.
Indemnitee agrees to [continue to] serve as a director of the Company. Indemnitee may at any time and for any reason resign from such position (subject to any other contractual obligation or any obligation imposed by law), in which event the Company
shall have no obligation under this Agreement to continue Indemnitee in such position. This Agreement shall not be deemed an employment contract between the Company (or any of its subsidiaries or any Enterprise) and Indemnitee. 

Section 2.     Definitions. 

As used in this Agreement: 

(a)    “Change in Control” 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.

 (b)    “Corporate Status” describes the status of a person as a current or former director of the
Company or current or former director, manager, partner, officer, employee, agent or trustee of any other Enterprise which such person is or was serving at the request of the Company. 

(c)    “Enforcement Expenses” shall include all reasonable attorneys’ fees, court costs, transcript
costs, fees of experts, travel expenses, duplicating costs, printing and binding costs, telephone charges, postage, delivery service fees, and all other out-of-pocket
disbursements or expenses of the types customarily incurred in connection with an action to enforce indemnification or advancement rights, or an appeal from such action. Expenses, however, shall not include fees, salaries, wages or benefits owed to
Indemnitee. 
 (d)    “Enterprise” shall mean any corporation (other than the Company), partnership,
joint venture, trust, employee benefit plan, limited liability company, or other legal entity of which Indemnitee is or was serving at the request of the Company as a director, manager, partner, officer, employee, agent or trustee. 

(e)    “Expenses” shall include all reasonable attorneys’ fees, court costs, transcript costs, fees
of experts, travel expenses, duplicating costs, printing and binding costs, telephone charges, postage, delivery service fees, and all other out-of-pocket disbursements
or expenses of the types customarily incurred in connection with prosecuting, defending, preparing to prosecute or defend, investigating, being or preparing to be a witness in, or otherwise participating in, a Proceeding or an appeal resulting from
a Proceeding. Expenses, however, shall not include amounts paid in settlement by Indemnitee, the amount of judgments or fines against Indemnitee or fees, salaries, wages or benefits owed to Indemnitee. 

  
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 (f)    “Independent Counsel” means a law firm, or a
partner (or, if applicable, member or shareholder) of such a law firm, that is experienced in matters of Canadian corporation law and neither presently is, nor in the past five (5) years has been, retained to represent: (i) the Company,
any subsidiary of the Company, any Enterprise or Indemnitee in any matter material to any such party; or (ii) any other party to the Proceeding giving rise to a claim for indemnification hereunder. Notwithstanding the foregoing, the term
“Independent Counsel” shall not include any person who, under the applicable standards of professional conduct then prevailing, would have a conflict of interest in representing either the Company or Indemnitee in an action to determine
Indemnitee’s rights under this Agreement. The Company agrees to pay the reasonable fees and expenses of the Independent Counsel referred to above and to fully indemnify such counsel against any and all expenses, claims, liabilities and damages
arising out of or relating to this Agreement or its engagement pursuant hereto. 
 (g)    The term
“Proceeding” shall include any threatened, pending or completed action, suit, arbitration, alternate dispute resolution mechanism, investigation, inquiry, administrative hearing or any other actual, threatened or completed
proceeding, whether brought in the right of the Company or otherwise and whether of a civil, criminal, administrative, regulatory or investigative nature, and whether formal or informal, in which Indemnitee was, is or will be involved as a party or
otherwise by reason of the fact that Indemnitee is or was a director of the Company or is or was serving at the request of the Company as a director, manager, partner, officer, employee, agent or trustee of any Enterprise or by reason of any action
taken by Indemnitee or of any action taken on his or her part while acting as a director of the Company or while serving at the request of the Company as a director, manager, partner, officer, employee, agent or trustee of any Enterprise, in each
case whether or not serving in such capacity at the time any liability or expense is incurred for which indemnification, reimbursement or advancement of expenses can be provided under this Agreement; provided, however, that the term
“Proceeding” shall not include any action, suit or arbitration, or part thereof, initiated by Indemnitee to enforce Indemnitee’s rights under this Agreement as provided for in Section 12(a) of this Agreement. 

Section 3.    Indemnity in Third-Party Proceedings. The Company shall indemnify Indemnitee to the extent set
forth in this Section 3 if Indemnitee is, or is threatened to be made, a party to or a participant in any Proceeding, other than a Proceeding by or in the right of the Company to procure a judgment in its favor. Pursuant to this Section 3,
Indemnitee shall be indemnified against all Expenses, judgments, fines, penalties, excise taxes, and amounts paid in settlement actually and reasonably incurred by Indemnitee or on his or her behalf in connection with such Proceeding or any claim,
issue or matter therein, if Indemnitee acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the best interests of the Company and, in the case of a criminal proceeding, had no reasonable cause to believe that
his or her conduct was unlawful. 
 Section 4.    Indemnity in Proceedings by or in the Right of the
Company. The Company shall indemnify Indemnitee to the extent set forth in this Section 4 if Indemnitee is, or 

  
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is threatened to be made, a party to or a participant in any Proceeding by or in the right of the Company to procure a judgment in its favor. Pursuant to this Section 4, Indemnitee shall be
indemnified against all Expenses actually and reasonably incurred by Indemnitee or on his or her behalf in connection with such Proceeding or any claim, issue or matter therein, if Indemnitee acted in good faith and in a manner he or she reasonably
believed to be in or not opposed to the best interests of the Company. No indemnification for Expenses shall be made under this Section 4 in respect of any claim, issue or matter as to which Indemnitee shall have been finally adjudged by a
court to be liable to the Company, unless and only to the extent that the Delaware Court of Chancery (the “Delaware Court”) shall determine upon application that, despite the adjudication of liability but in view of all the
circumstances of the case, Indemnitee is fairly and reasonably entitled to indemnification for such expenses as the Delaware Court shall deem proper. 

Section 5.    Indemnification for Expenses of a Party Who is Wholly or Partly Successful. Notwithstanding any
other provisions of this Agreement and except as provided in Section 7, to the extent that Indemnitee is a party to or a participant in any Proceeding and is successful in such Proceeding or in defense of any claim, issue or matter therein, the
Company shall indemnify Indemnitee against all Expenses actually and reasonably incurred by him or her in connection therewith. If Indemnitee is not wholly successful in such Proceeding but is successful as to one or more but less than all claims,
issues or matters in such Proceeding, the Company shall indemnify Indemnitee against all Expenses actually and reasonably incurred by Indemnitee or on his or her behalf in connection with each successfully resolved claim, issue or matter. For
purposes of this Section and without limitation, the termination of any claim, issue or matter in such a Proceeding by dismissal, with or without prejudice, shall be deemed to be a successful result as to such claim, issue or matter. 

Section 6.    Reimbursement for Expenses of a Witness or in Response to a Subpoena. Notwithstanding any other
provision of this Agreement, to the extent that Indemnitee, by reason of his or her Corporate Status, (i) is a witness in any Proceeding to which Indemnitee is not a party and is not threatened to be made a party or (ii) receives a
subpoena with respect to any Proceeding to which Indemnitee is not a party and is not threatened to be made a party, the Company shall reimburse Indemnitee for all Expenses actually and reasonably incurred by him or her or on his or her behalf in
connection therewith. 
 Section 7.    Exclusions. Notwithstanding any provision in this Agreement to the
contrary, the Company shall not be obligated under this Agreement: 
 (a)    to indemnify for amounts otherwise
indemnifiable hereunder (or for which advancement is provided hereunder) if and to the extent that Indemnitee has otherwise actually received such amounts under any insurance policy, contract, agreement or otherwise; provided that the
foregoing shall not affect the rights of Indemnitee or the Secondary Indemnitors as set forth in Section 13(c); 

(b)    to indemnify for an accounting of profits made from the purchase and sale (or sale and purchase) by Indemnitee of
securities of the Company within the meaning of Section 16(b) of the Securities Exchange Act of 1934, as amended, or similar provisions of state statutory law or common law, or from the purchase or sale by Indemnitee of such securities in
violation of Section 306 of the Sarbanes Oxley Act of 2002 (“SOX”); 

  
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 (c)    to indemnify with respect to any Proceeding, or
part thereof, brought by Indemnitee against the Company, any legal entity which it controls, any director or officer thereof or any third party, unless (i) the Board has consented to the initiation of such Proceeding or part thereof and
(ii) the Company provides the indemnification, in its sole discretion, pursuant to the powers vested in the Company under applicable law; provided, however, that this Section 7(c) shall not apply to (A) counterclaims or
affirmative defenses asserted by Indemnitee in an action brought against Indemnitee or (B) any action brought by Indemnitee for indemnification or advancement from the Company under this Agreement or under any directors’ and officers’
liability insurance policies maintained by the Company in the suit for which indemnification or advancement is being sought as described in Section 12; 

(d)    to provide any indemnification or advancement of Expenses unless Indemnitee acted honestly and in good faith with a
view to the best interests of the Company, or, as the case may be, to the best interests of the other Enterprise for which the individual acted as director or officer or in a similar capacity at the Company’s request; 

(e)    to provide any indemnification or advancement of Expenses in the case of a criminal or administrative Proceeding
that is enforced by monetary penalty unless Indemnitee had reasonable grounds for believing that Indemnitee’s conduct was lawful; or1 

(f)    to provide any indemnification or advancement of Expenses that is prohibited by applicable law (as such law exists
at the time payment would otherwise be required pursuant to this Agreement). 
 Section 8.    Advancement of
Expenses. Subject to Section 9(b), the Company shall advance, to the extent not prohibited by law, the Expenses incurred by Indemnitee in connection with any Proceeding, and such advancement shall be made as incurred, and such advancement
shall be made within thirty (30) days after the receipt by the Company of a statement or statements requesting such advances (including any invoices received by Indemnitee, which such invoices may be redacted as necessary to avoid the waiver of
any privilege accorded by applicable law) from time to time, whether prior to or after final disposition of any Proceeding. Advances shall be unsecured and interest free. Advances shall be made without regard to Indemnitee’s (i) ability to
repay the expenses, (ii) ultimate entitlement to indemnification under the other provisions of this Agreement, and (iii) entitlement to and availability of insurance coverage, including advancement, payment or reimbursement of defense
costs, expenses of covered loss under the provisions of any applicable insurance policy (including , without limitation, whether such advancement, payment or reimbursement is withheld, conditioned or delayed by the insurer(s)). Indemnitee shall
qualify for advances upon the execution and delivery to the Company of this Agreement which shall constitute an undertaking providing that Indemnitee undertakes to the fullest extent required by law to repay the advance if and to the extent that it
is ultimately determined by a court of competent jurisdiction in a final judgment, 
  

	1 	 NTD: Language has been inserted pursuant to s. 124(3) of the CBCA. 

  
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not subject to appeal, that Indemnitee is not entitled to be indemnified by the Company. The right to advances under this paragraph shall in all events continue until final disposition of any
Proceeding, including any appeal therein. Nothing in this Section 8 shall limit Indemnitee’s right to advancement pursuant to Section 12(e) of this Agreement. 

Section 9.    Procedure for Notification and Defense of Claim. 

(a)    To obtain indemnification under this Agreement, Indemnitee shall submit to the Company a written request therefor
specifying the basis for the claim, the amounts for which Indemnitee is seeking payment under this Agreement, and all documentation related thereto as reasonably requested by the Company. 

(b)    In the event that the Company shall be obligated hereunder to provide indemnification for or make any advancement
of Expenses with respect to any Proceeding, the Company shall be entitled to assume the defense of such Proceeding, or any claim, issue or matter therein, with counsel approved by Indemnitee (which approval shall not be unreasonably withheld or
delayed) upon the delivery to Indemnitee of written notice of the Company’s election to do so. After delivery of such notice, approval of such counsel by Indemnitee and the retention of such counsel by the Company, the Company will not be
liable to Indemnitee under this Agreement for any fees or expenses of separate counsel subsequently employed by or on behalf of Indemnitee with respect to the same Proceeding; provided that (i) Indemnitee shall have the right to employ
separate counsel in any such Proceeding at Indemnitee’s expense and (ii) if (A) the employment of separate counsel by Indemnitee has been previously authorized by the Company, (B) Indemnitee shall have reasonably concluded that there
may be a conflict of interest between the Company and Indemnitee in the conduct of such defense, or (C) the Company shall not continue to retain such counsel to defend such Proceeding, then the fees and expenses actually and reasonably incurred
by Indemnitee with respect to his or her separate counsel shall be Expenses hereunder. 
 (c)    In the event that the
Company does not assume the defense in a Proceeding pursuant to paragraph (b) above, then the Company will be entitled to participate in the Proceeding at its own expense. 

(d)    The Company shall not be liable to indemnify Indemnitee under this Agreement for any amounts paid in settlement of
any Proceeding effected without its prior written consent (which consent shall not be unreasonably withheld or delayed). The Company shall not, without the prior written consent of Indemnitee (which consent shall not be unreasonably withheld or
delayed), enter into any settlement which (i) includes an admission of fault of Indemnitee, any non-monetary remedy imposed on Indemnitee or any monetary damages for which Indemnitee is not wholly and
actually indemnified hereunder or (ii) with respect to any Proceeding with respect to which Indemnitee may be or is made a party or may be otherwise entitled to seek indemnification hereunder, does not include the full release of Indemnitee
from all liability in respect of such Proceeding. 

  
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 Section 10.    Procedure Upon Application for
Indemnification. 
 (a)    Upon written request by Indemnitee for indemnification pursuant to Section 9(a), a
determination, if such determination is required by applicable law, with respect to Indemnitee’s entitlement to indemnification hereunder shall be made in the specific case by one of the following methods: (x) if a Change in Control shall
have occurred, by Independent Counsel in a written opinion to the Board; or (y) if a Change in Control shall not have occurred: (i) by a majority vote of the disinterested directors, even though less than a quorum; (ii) by a committee
of disinterested directors designated by a majority vote of the disinterested directors, even though less than a quorum; or (iii) if there are no disinterested directors or if the disinterested directors so direct, by Independent Counsel in a
written opinion to the Board. For purposes hereof, disinterested directors are those members of the Board who are not parties to the action, suit or proceeding in respect of which indemnification is sought. In the case that such determination is
made by Independent Counsel, a copy of Independent Counsel’s written opinion shall be delivered to Indemnitee and, if it is so determined that Indemnitee is entitled to indemnification, payment to Indemnitee shall be made within thirty
(30) days after such determination. Indemnitee shall cooperate with the Independent Counsel or the Company, as applicable, in making such determination with respect to Indemnitee’s entitlement to indemnification, including providing to
such counsel or the Company, upon reasonable advance request, any documentation or information which is not privileged or otherwise protected from disclosure and which is reasonably available to Indemnitee and reasonably necessary to such
determination. Any out-of-pocket costs or expenses (including reasonable attorneys’ fees and disbursements) actually and reasonably incurred by Indemnitee in so
cooperating with the Independent Counsel or the Company shall be borne by the Company (irrespective of the determination as to Indemnitee’s entitlement to indemnification) and the Company hereby indemnifies and agrees to hold Indemnitee
harmless therefrom. 
 (b)    If the determination of entitlement to indemnification is to be made by Independent
Counsel pursuant to Section 10(a), the Independent Counsel shall be selected by the Board if a Change in Control shall not have occurred or, if a Change in Control shall have occurred, by Indemnitee. Indemnitee or the Company, as the case may
be, may, within ten (10) days after written notice of such selection, deliver to the Company or Indemnitee, as the case may be, a written objection to such selection; provided, however, that such objection may be asserted only on
the ground that the Independent Counsel so selected does not meet the requirements of “Independent Counsel” as defined in Section 2 of this Agreement, and the objection shall set forth with particularity the factual basis of such
assertion. Absent a proper and timely objection, the person so selected shall act as Independent Counsel. If such written objection is so made and substantiated, the Independent Counsel so selected may not serve as Independent Counsel unless and
until such objection is withdrawn or the Delaware Court has determined that such objection is without merit. If, within twenty (20) days after the later of (i) submission by Indemnitee of a written request for indemnification pursuant to
Section 9(a), and (ii) the final disposition of the Proceeding, including any appeal therein, no Independent Counsel shall have been selected without objection, either Indemnitee or the Company may petition the Delaware Court for
resolution of any objection which shall have been made by Indemnitee or the Company to the selection of Independent Counsel and/or for the appointment as Independent Counsel of a person selected by the court or by such other person as the court
shall designate. The person with respect to whom all objections are so resolved or the person so appointed shall act as Independent Counsel under Section 10(a) hereof. Upon the due commencement of any judicial proceeding or arbitration pursuant
to Section 12(a) of this Agreement, Independent Counsel shall be discharged and relieved of any further responsibility in such capacity (subject to the applicable standards of professional conduct then prevailing). 

  
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 Section 11.    Presumptions and Effect of Certain
Proceedings. 
 (a)    To the extent permitted by applicable law, in making a determination with respect to
entitlement to indemnification hereunder, it shall be presumed that Indemnitee is entitled to indemnification under this Agreement if Indemnitee has submitted a request for indemnification in accordance with Section 9(a) of this Agreement, and
the Company shall have the burden of proof to overcome that presumption in connection with the making of any determination contrary to that presumption. Neither (i) the failure of the Company or of Independent Counsel to have made a
determination prior to the commencement of any action pursuant to this Agreement that indemnification is proper in the circumstances because Indemnitee has met the applicable standard of conduct, nor (ii) an actual determination by the Company
or by Independent Counsel that Indemnitee has not met such applicable standard of conduct, shall be a defense to the action or create a presumption that Indemnitee has not met the applicable standard of conduct. 

(b)    The termination of any Proceeding or of any claim, issue or matter therein, by judgment, order, settlement or
conviction, or upon a plea of guilty, nolo contendere or its equivalent, shall not (except as otherwise expressly provided in this Agreement) of itself adversely affect the right of Indemnitee to indemnification or create a presumption
that Indemnitee did not act in good faith and in a manner which he or she reasonably believed to be in or not opposed to the best interests of the Company or, with respect to any criminal Proceeding, that Indemnitee had reasonable cause to believe
that his or her conduct was unlawful. 
 (c)    The knowledge and/or actions, or failure to act, of any director,
manager, partner, officer, employee, agent or trustee of the Company, any subsidiary of the Company, or any Enterprise shall not be imputed to Indemnitee for purposes of determining the right to indemnification under this Agreement. 

Section 12.    Remedies of Indemnitee. 

(a)    Subject to Section 12(f), in the event that (i) a determination is made pursuant to Section 10 of
this Agreement that Indemnitee is not entitled to indemnification under this Agreement, (ii) advancement of Expenses is not timely made pursuant to Section 8 of this Agreement, (iii) no determination of entitlement to indemnification
shall have been made pursuant to Section 10(a) of this Agreement within sixty (60) days after receipt by the Company of the request for indemnification for which a determination is to be made other than by Independent Counsel,
(iv) payment of indemnification or reimbursement of expenses is not made pursuant to Section 5 or 6 or the last sentence of Section 10(a) of this Agreement within thirty (30) days after receipt by the Company of a written request
therefor (including any invoices received by Indemnitee, which such invoices may be redacted as necessary to avoid the waiver of any privilege accorded by applicable law) or (v) payment of indemnification pursuant to Section 3 or 4 of this
Agreement is not made within thirty (30) days after a determination has been made that Indemnitee is entitled to indemnification, Indemnitee shall be entitled to an 

  
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adjudication by the Delaware Court of his or her entitlement to such indemnification or advancement. Alternatively, Indemnitee, at his or her option, may seek an award in arbitration to be
conducted by a single arbitrator pursuant to the Commercial Arbitration Rules of the American Arbitration Association. Indemnitee shall commence such proceeding seeking an adjudication or an award in arbitration within 180 days following the date on
which Indemnitee first has the right to commence such proceeding pursuant to this Section 12(a); provided, however, that the foregoing time limitation shall not apply in respect of a proceeding brought by Indemnitee to enforce his
or her rights under Section 5 of this Agreement. The Company shall not oppose Indemnitee’s right to seek any such adjudication or award in arbitration. 

(b)    In the event that a determination shall have been made pursuant to Section 10(a) of this Agreement that
Indemnitee is not entitled to indemnification, any judicial proceeding or arbitration commenced pursuant to this Section 12 shall be conducted in all respects as a de novo trial, or arbitration, on the merits and Indemnitee shall not be
prejudiced by reason of that adverse determination. In any judicial proceeding or arbitration commenced pursuant to this Section 12, the Company shall have the burden of proving Indemnitee is not entitled to indemnification or advancement, as
the case may be. 
 (c)    If a determination shall have been made pursuant to Section 10(a) of this Agreement that
Indemnitee is entitled to indemnification, the Company shall be bound by such determination in any judicial proceeding or arbitration commenced pursuant to this Section 12, absent (i) a misstatement by Indemnitee of a material fact, or an
omission of a material fact necessary to make Indemnitee’s statement not materially misleading, in connection with the request for indemnification, or (ii) a prohibition of such indemnification under applicable law. 

(d)    The Company shall be precluded from asserting in any judicial proceeding or arbitration commenced pursuant to this
Section 12 that the procedures and presumptions of this Agreement are not valid, binding and enforceable and shall stipulate in any such court or before any such arbitrator that the Company is bound by all the provisions of this Agreement. 

(e)    The Company shall indemnify Indemnitee to the fullest extent permitted by law against any and all Enforcement
Expenses and, if requested by Indemnitee, shall (within thirty (30) days after receipt by the Company of a written request therefor) advance, to the extent not prohibited by law, such Enforcement Expenses to Indemnitee, which are incurred by
Indemnitee in connection with any action brought by Indemnitee for indemnification or advancement from the Company under this Agreement or under any directors’ and officers’ liability insurance policies maintained by the Company in the
suit for which indemnification or advancement is being sought. Such written request for advancement shall include invoices received by Indemnitee in connection with such Enforcement Expenses but, in the case of invoices in connection with legal
services, any references to legal work performed or to expenditures made that would cause Indemnitee to waive any privilege accorded by applicable law need not be included with the invoice. 

(f)    Notwithstanding anything in this Agreement to the contrary, no determination as to entitlement to indemnification
under this Agreement shall be required to be made prior to the final disposition of the Proceeding, including any appeal therein. 

  
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Section 13.    Non-exclusivity; Survival of Rights; Insurance; Primacy of
Indemnification; Subrogation. 
 (a)    The rights of indemnification and to receive advancement as provided by this
Agreement shall not be deemed exclusive of any other rights to which Indemnitee may at any time be entitled under applicable law, the Bylaws, any agreement, a vote of shareholders or a resolution of directors, or otherwise. No amendment, alteration
or repeal of this Agreement or of any provision hereof shall limit or restrict any right of Indemnitee under this Agreement in respect of any action taken or omitted by such Indemnitee in his or her Corporate Status prior to such amendment,
alteration or repeal. To the extent that a change in Canadian law, whether by statute or judicial decision, permits greater indemnification or advancement than would be afforded currently under the Bylaws and this Agreement, it is the intent of the
parties hereto that Indemnitee shall enjoy by this Agreement the greater benefits so afforded by such change. No right or remedy herein conferred is intended to be exclusive of any other right or remedy, and every other right and remedy shall be
cumulative and in addition to every other right and remedy given hereunder or now or hereafter existing at law or in equity or otherwise. The assertion or employment of any right or remedy hereunder, or otherwise, shall not prevent the concurrent
assertion or employment of any other right or remedy. 
 (b)    To the extent that the Company maintains an insurance
policy or policies providing liability insurance for directors, managers, partners, officers, employees, agents or trustees of the Company or of any other Enterprise, Indemnitee shall be covered by such policy or policies in accordance with its or
their terms to the maximum extent of the coverage available for any such director, manager, partner, officer, employee, agent or trustee under such policy or policies. If, at the time of the receipt of a notice of a claim pursuant to the terms
hereof, the Company has director and officer liability insurance in effect, the Company shall give prompt notice of the commencement of such proceeding to the insurers in accordance with the procedures set forth in the respective policies. The
Company shall thereafter take all necessary or desirable action to cause such insurers to pay, on behalf of Indemnitee, all amounts payable as a result of such proceeding in accordance with the terms of such policies. 

(c)    [The Company hereby acknowledges that Indemnitee has certain rights to indemnification, advancement of expenses
and/or insurance provided by [                    ] and certain of its affiliates (collectively, the “Secondary Indemnitors”). The
Company hereby agrees (i) that it is the indemnitor of first resort (i.e., its obligations to Indemnitee are primary and any obligation of the Secondary Indemnitors to advance expenses or to provide indemnification for the same expenses
or liabilities incurred by Indemnitee are secondary), (ii) that it shall be required to advance the full amount of expenses incurred by Indemnitee and shall be liable for the full amount of all Expenses, judgments, penalties, fines and amounts paid
in settlement to the extent legally permitted and as required by the terms of this Agreement and the Bylaws (or any other agreement between the Company and Indemnitee), without regard to any rights Indemnitee may have against the Secondary
Indemnitors, and (iii) that it irrevocably waives, relinquishes and releases the Secondary Indemnitors from any and all claims against the Secondary Indemnitors for contribution, subrogation or any other recovery of any kind in respect thereof.
The Company further agrees that no advancement or payment by the Secondary Indemnitors on behalf of Indemnitee with respect to any claim for which Indemnitee has sought indemnification from the Company shall affect the foregoing and the Secondary
Indemnitors shall have a right of 

  
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contribution and/or be subrogated to the extent of such advancement or payment to all of the rights of recovery of Indemnitee against the Company. The Company and Indemnitee agree that the
Secondary Indemnitors are express third party beneficiaries of the terms of this Section 13(c).] 
 (d)    [Except
as provided in paragraph (c) above,] in the event of any payment under this Agreement, the Company shall be subrogated to the extent of such payment to all of the rights of recovery of Indemnitee [(other than against the Secondary
Indemnitors)], who shall execute all papers required and take all action necessary to secure such rights, including execution of such documents as are necessary to enable the Company to bring suit to enforce such rights. 

(e)    [Except as provided in paragraph (c) above,] the Company’s obligation to provide indemnification or
advancement hereunder to Indemnitee who is or was serving at the request of the Company as a director, manager, partner, officer, employee, agent or trustee of any other Enterprise shall be reduced by any amount Indemnitee has actually received as
indemnification or advancement from such other Enterprise. 
 Section 14.     Duration of Agreement. This
Agreement shall continue until and terminate upon the later of: (a) ten (10) years after the date that Indemnitee shall have ceased to serve as a director of the Company or (b) one (1) year after the final termination of any Proceeding,
including any appeal, then pending in respect of which Indemnitee is granted rights of indemnification or advancement hereunder and of any proceeding commenced by Indemnitee pursuant to Section 12 of this Agreement relating thereto. This
Agreement shall be binding upon the Company and its successors and assigns and shall inure to the benefit of Indemnitee and his or her heirs, executors and administrators. The Company shall require and cause any successor (whether direct or indirect
by purchase, merger, amalgamation, plan of arrangement, consolidation or otherwise) to all, substantially all or a substantial part, of the business and/or assets of the Company, by written agreement in form and substance satisfactory to Indemnitee,
expressly to assume and agree to perform this Agreement in the same manner and to the same extent that the Company would be required to perform if no such succession had taken place. 

Section 15.    Severability. If any provision or provisions of this Agreement shall be held to be invalid,
illegal or unenforceable for any reason whatsoever: (a) the validity, legality and enforceability of the remaining provisions of this Agreement (including, without limitation, each portion of any section of this Agreement containing any such
provision held to be invalid, illegal or unenforceable, that is not itself invalid, illegal or unenforceable) shall not in any way be affected or impaired thereby and shall remain enforceable to the fullest extent permitted by law; (b) such
provision or provisions shall be deemed reformed to the extent necessary to conform to applicable law and to give the maximum effect to the intent of the parties hereto; and (c) to the fullest extent possible, the provisions of this Agreement
(including, without limitation, each portion of any section of this Agreement containing any such provision held to be invalid, illegal or unenforceable, that is not itself invalid, illegal or unenforceable) shall be construed so as to give effect
to the intent manifested thereby. 

  
 11 

 Section 16.    Enforcement. 

(a)    The Company expressly confirms and agrees that it has entered into this Agreement and assumed the obligations
imposed on it hereby in order to induce Indemnitee to serve or continue to serve as a director of the Company, and the Company acknowledges that Indemnitee is relying upon this Agreement in serving as a director of the Company. 

(b)    This Agreement constitutes the entire agreement between the parties hereto with respect to the subject matter
hereof and supersedes all prior agreements and understandings, oral, written and implied, between the parties hereto with respect to the subject matter hereof; provided, however, that this Agreement is a supplement to and in
furtherance of the Bylaws and applicable law, and shall not be deemed a substitute therefor, nor to diminish or abrogate any rights of Indemnitee thereunder. 

Section 17.    Modification and Waiver. No supplement, modification or amendment, or waiver of any provision,
of this Agreement shall be binding unless executed in writing by the parties thereto. No waiver of any of the provisions of this Agreement shall be deemed or shall constitute a waiver of any other provisions of this Agreement nor shall any waiver
constitute a continuing waiver. No supplement, modification or amendment of this Agreement or of any provision hereof shall limit or restrict any right of Indemnitee under this Agreement in respect of any action taken or omitted by such Indemnitee
prior to such supplement, modification or amendment. 
 Section 18.    Notice by Indemnitee. Indemnitee
agrees promptly to notify the Company in writing upon being served with any summons, citation, subpoena, complaint, indictment, information or other document relating to any Proceeding or matter which may be subject to indemnification, reimbursement
or advancement as provided hereunder. The failure of Indemnitee to so notify the Company shall not relieve the Company of any obligation which it may have to Indemnitee under this Agreement or otherwise. 

Section 19.    Notices. All notices, requests, demands and other communications under this Agreement shall be
in writing and shall be deemed to have been duly given if (i) delivered by hand and receipted for by the party to whom said notice or other communication shall have been directed, (ii) mailed by certified or registered mail with postage
prepaid, on the third business day after the date on which it is so mailed, (iii) mailed by reputable overnight courier and receipted for by the party to whom said notice or other communication shall have been directed or (iv) sent by
facsimile transmission, with receipt of oral confirmation that such transmission has been received: 
 (a)    If to
Indemnitee, at such address as Indemnitee shall provide to the Company. 
 (b)    If to the Company to: 

Fusion Pharmaceuticals Inc. 

270 Longwood Road South 

Hamilton, Ontario, Canada L8P 0A6 

Attention: John Crowley 

  
 12 

 or to any other address as may have been furnished to Indemnitee by the Company. 

Section 20.    Contribution. To the fullest extent permissible under applicable law, if the indemnification
provided for in this Agreement is unavailable to Indemnitee for any reason whatsoever, the Company, in lieu of indemnifying Indemnitee, shall contribute to the amount incurred by Indemnitee, whether for judgments, fines, penalties, excise taxes,
amounts paid or to be paid in settlement and/or for Expenses, in connection with any Proceeding in such proportion as is deemed fair and reasonable in light of all of the circumstances in order to reflect (i) the relative benefits received by
the Company and Indemnitee in connection with the event(s) and/or transaction(s) giving rise to such Proceeding; and/or (ii) the relative fault of the Company (and its directors, officers, employees and agents) and Indemnitee in connection with
such event(s) and/or transactions. 
 Section 21.    Internal Revenue Code Section 409A.
The Company intends for this Agreement to comply with the Indemnification exception under Section 1.409A-1(b)(10) of the regulations promulgated under the Internal Revenue Code of 1986, as amended (the
“Code”), which provides that indemnification of, or the purchase of an insurance policy providing for payments of, all or part of the expenses incurred or damages paid or payable by Indemnitee with respect to a bona fide claim
against Indemnitee or the Company do not provide for a deferral of compensation, subject to Section 409A of the Code, where such claim is based on actions or failures to act by Indemnitee in his or her capacity as a service provider of the
Company. The parties intend that this Agreement be interpreted and construed with such intent. 

Section 22.    Applicable Law and Consent to Jurisdiction. This Agreement and the legal relations among the
parties shall be governed by, and construed and enforced in accordance with, the laws of the State of Delaware, without regard to its conflict of laws rules. Except with respect to any arbitration commenced by Indemnitee pursuant to
Section 12(a) of this Agreement, the Company and Indemnitee hereby irrevocably and unconditionally (i) agree that any action or proceeding arising out of or in connection with this Agreement shall be brought only in the Delaware Court, and
not in any other state or federal court in the United States of America or any court in any other country, (ii) consent to submit to the exclusive jurisdiction of the Delaware Court for purposes of any action or proceeding arising out of or in
connection with this Agreement, (iii) consent to service of process at the address set forth in Section 19 of this Agreement with the same legal force and validity as if served upon such party personally within the State of Delaware,
(iv) waive any objection to the laying of venue of any such action or proceeding in the Delaware Court, and (v) waive, and agree not to plead or to make, any claim that any such action or proceeding brought in the Delaware Court has been
brought in an improper or inconvenient forum. 
 Section 23.    Headings. The headings of the paragraphs of
this Agreement are inserted for convenience only and shall not be deemed to constitute part of this Agreement or to affect the construction thereof. 

Section 24.    Identical Counterparts. This Agreement may be executed in one or more counterparts, each of
which shall for all purposes be deemed to be an original but all of which together shall constitute one and the same Agreement. Only one such counterpart signed by the party against whom enforceability is sought needs to be produced to evidence the
existence of this Agreement. 

  
 13 

 [Remainder of Page Intentionally Left Blank] 

  
 14 

 IN WITNESS WHEREOF, the parties have caused this Agreement to be signed as of the day and
year first above written. 
  

			
	FUSION PHARMACEUTICALS INC.
		
	By:	 	
                     
                   

		 	    Name:
		 	    Title:
	
	  

		 	    [Name of Indemnitee]EX-10.7

 Exhibit 10.7 

EMPLOYMENT AGREEMENT 

This Employment Agreement (“Agreement”) is made between Fusion Pharmaceuticals Inc. (the “Company”), and John Valliant
(the “Executive”) and is effective as of the closing of the first underwritten public offering of the equity securities of the Company pursuant to an effective registration statement under the Securities Act of 1933, as amended (United
States) (the “Effective Date”). Except with respect to the Restrictive Covenants Agreement and the Equity Documents (each as defined below), this Agreement supersedes in all respects all prior agreements between the Executive and the
Company regarding the subject matter herein, including without limitation the Employment Agreement between the Executive and the Company dated October 12, 2018 (the “Prior Agreement”). 

WHEREAS, the Company desires to continue to employ the Executive and the Executive desires to continue to be employed by the Company on the
new terms and conditions contained herein. 
 NOW, THEREFORE, in consideration of the foregoing mutual covenants and agreements
contained herein and other good and valuable consideration, including a one-time retention bonus, the receipt and sufficiency of which is hereby acknowledged, the parties agree as follows: 

1.    Employment. 

(a)    Term. The Company shall employ the Executive and the Executive shall be employed by the Company pursuant to
this Agreement commencing as of the Effective Date and continuing until such employment is terminated in accordance with the provisions hereof (the “Term”). The Company shall recognize December 22, 2014 as the Executive’s start
date for all service-based purposes. 
 (b)     Position and Duties. The Executive shall serve as the Chief
Executive Officer of the Company and shall have such powers and duties as may from time to time be prescribed by the Board of Directors of the Company (the “Board”) or other duly authorized executive. 

With the exception of the Executive’s professional duties in connection with his position as a professor at McMaster (as set out in the memorandum of
understanding amongst the Executive, the Company and McMaster dated July 1, 2018 (the “Memorandum of Understanding”)) and the Executive’s role as a member of the Board of Directors of the Centre of Probe Development and
Commercialization or its affiliates or subsidiaries (collectively, “CPDC”) the Executive shall devote his full business time and energy to the Company and shall not engage in any other business, occupation or professional activity or
become a director, employee, consultant or agent of any other entity during his employment with the Company, except with the express written consent of the Board, which shall not be unreasonably withheld for
non-competitive, civic or charitable opportunities. Without limiting the foregoing, nothing in this Section 1(b) is intended to limit the Executive’s ability to be a shareholder in any company
conditional on such companies not operating a business that is competitive with the products or services of the Company. 

 2.    Compensation and Related Matters. 

(a)    Base Salary. The Executive’s initial base salary shall be paid at the rate of $542,400
USD per year. The Executive’s base salary shall be subject to periodic review by the Board or the Compensation Committee of the Board (the “Compensation Committee”). The base salary in effect at any given time is
referred to herein as “Base Salary.” At the Company’s sole discretion, the Base Salary will be converted into and payable as Canadian dollars at the exchange rate on the date of payment as set by the Company’s financial
institution. In accordance with the terms and conditions of the Memorandum of Understanding, the Company has agreed to reimburse McMaster for seventy-five percent (75%) of McMaster’s payment of the Executive’s annual McMaster salary and
benefits (the “McMaster Obligation”). Accordingly, the portion of the McMaster Obligation attributable to repayment of the Executive’s annual McMaster salary (the “McMaster Amount”) shall be deducted from the Base Salary and
paid to McMaster directly. The amount that is equal to the Base Salary, less the McMaster Amount, shall be paid to the Executive directly in installments in accordance with the Company’s payroll practices, as amended from time to time. The
Executive’s Base Salary, prior to the deduction of the McMaster Amount, shall not be lower than the annualized base salary of any other employee of the Company. If at any time, the Memorandum of Understanding ceases, expires and is not renewed,
and/or is not enforceable for any reason, the Company shall no longer be required to provide McMaster with the McMaster Obligation and instead, shall provide the Executive directly with 100% of his Base Salary in accordance with the Company’s
payroll practices, as amended from time to time. 
 (b)    Incentive Compensation. The Executive
shall be eligible to receive an annual discretionary bonus (the “Bonus”) of up to fifty percent (50%) of the Base Salary subject to the achievement of objectives established and assessed by the Board or the Compensation
Committee from time to time. The actual amount of the Executive’s annual incentive compensation, if any, shall be determined in the sole discretion of the Board or the Compensation Committee acting in good faith. Any Bonus that the Executive
may receive may vary significantly from year to year. There is no representation that a Bonus in one year will be comparable to another year. There is no implied term that, if the amount of any Bonus is lower in any subsequent year, the Company will
compensate the Executive for such difference. Under no circumstances is the Bonus to be considered part of the Base Salary or other regular employment income. The Bonus, if any, will be paid when the Company normally pays such bonuses and is not
earned or accrued until the Bonus payout date. Except as otherwise provided herein, bonus eligibility is conditional upon the Executive remaining in the active employment of the Company on the day such incentive compensation is paid. Except as may
be expressly required by the Employment Standards Act, 2000, as amended or replaced (the “ESA”) and except as otherwise provided herein, if prior to the Bonus being declared or paid either (a) the Executive’s active
employment with the Company ceases for any reason whatsoever, or (b) the Executive has given or received notice of termination, the Executive will not be eligible for Bonus consideration for that year or for any resulting notice period, arising
under contract, statute or common law. 
 (c)    Expenses. The Executive shall be entitled to
receive prompt reimbursement for all reasonable expenses incurred by the Executive during the Term in performing services hereunder, in accordance with the policies and procedures then in effect and established by the Company for its executive
officers. 

  
 2 

 (d)    Other Benefits. The Executive shall be
eligible to participate in or receive benefits under the Company’s employee benefit plans in effect from time to time, subject to the terms of such plans. 

(e)    Retention Bonus. The Executive shall be provided with a
one-time retention bonus of $1000 as consideration for entering into this Agreement. 

(f)    Vacation. Subject to the terms and conditions of the Company’s vacation policy in effect
from time to time, the Executive will be eligible to accrue up to four (4) weeks of paid vacation in each calendar year, accrued pro-rata on a monthly basis, to be taken at times agreed upon by the
Executive and the Company. Vacation time must accrue before the Executive may use it, except upon written approval of the Company, which approval will be at the sole discretion of the Company. The Company reserves the right to require the Executive
to take some or all of the accrued vacation days at any time during scheduled or unscheduled office shut-down periods, at its sole discretion. Forfeiture of unused vacation days will be subject to the Company’s vacation policy as in effect from
time to time. 
 (g)    Equity. The equity awards held by the Executive shall continue to be
governed by the terms and conditions of the Company’s applicable equity incentive plan(s) and the applicable award agreement(s) governing the terms of such equity awards held by the Executive (collectively, the “Equity Documents”).

 (h)    Indemnification. During and after the Term, the Executive shall be entitled to
indemnification pursuant to the Company’s articles of organization and/or by-laws, as applicable, and applicable provincial law. 

3.    Termination. In the event Executive’s employment is terminated, the Executive shall be deemed to have
resigned from all officer and Board member positions that the Executive holds with the Company or any of its respective subsidiaries and affiliates upon the termination of the Executive’s employment for any reason. The Executive shall execute
any documents in reasonable form as may be requested to confirm or effectuate any such resignations. 
 The Executive’s employment hereunder may be
terminated without any breach of this Agreement under the following circumstances: 

(a)    Death. The Executive’s employment hereunder shall terminate upon death. 

(b)    Frustration of Contract. If the Executive is unable to perform the Executive’s essential
employment related duties for a period of more than either three (3) consecutive months, or one-hundred and eighty (180) days in the aggregate during any twelve (12) month period, and there is
no reasonable prospect that the Executive will be able to perform the essential duties of the Executive’s position with or without accommodation in the reasonable foreseeable future, any future absence by the Executive will constitute undue

  
 3 

 
hardship for the Company and the Executive’s employment shall be deemed frustrated and terminated. If any question shall arise as to whether during any period the Executive is disabled so as
to be unable to perform the essential functions of the Executive’s then existing position or positions with or without reasonable accommodation, the Executive may, and at the request of the Company shall, submit to the Company a certification
in reasonable detail by a physician selected by the Company to whom the Executive or the Executive’s guardian has no reasonable objection as to whether the Executive is so disabled or how long such disability is expected to continue, and such
certification shall for the purposes of this Agreement be conclusive of the issue. The Executive shall cooperate with any reasonable request of the physician in connection with such certification. If such question shall arise and the Executive shall
fail to submit such certification, the Company’s determination of such issue shall be binding on the Executive. 

(c)    Termination by Company for Cause. The Company may terminate the Executive’s employment
hereunder for Cause. For purposes of this Agreement, “Cause” shall mean any grounds at common law for which an employer is entitled to dismiss an employee summarily, and shall mean, without limitation, the following: 

 

	 	i.	 actions or omissions by the Executive constituting a material act of misconduct in connection with the
performance of the Executive’s duties, including, without limitation, (A) willful failure or refusal to perform material responsibilities that have been requested by the Board; (B) dishonesty with respect to any material
matter; or (C) misappropriation of funds or property of the Company or any of its subsidiaries or affiliates other than the occasional, customary and de minimis use of Company property for personal purposes; 

 

	 	ii.	 the conviction of the Executive for a criminal offence where such conviction is detrimental to the business or
reputation of the Company; 

  

	 	iii.	 any misconduct by the Executive, regardless of whether or not in the course of the Executive’s employment,
that would reasonably be expected to result in material injury or reputational harm to the Company or any of its subsidiaries or affiliates if the Executive were to continue to be employed in the same position; 

 

	 	iv.	 a breach by the Executive of any of the material provisions contained in this Agreement or the Restrictive
Covenants Agreement (as defined herein); 

  

	 	v.	 a material violation by the Executive of any of the Company’s written policies that would reasonably be
expected to result in material injury or reputational harm to the Company or any of its subsidiaries or affiliates if the Executive were to continue to be employed in the same position;  

  
 4 

	 	vi.	 actions or omissions on the part of the Executive constituting willful misconduct, disobedience, or willful
neglect of duty that is not trivial and has not been condoned by the Company; or 

  

	 	vii.	 the Executive’s failure to cooperate with a bona fide internal investigation or an investigation by
regulatory or law enforcement authorities, after being instructed by the Company to cooperate, or the willful destruction or failure to preserve documents or other materials known to be relevant to such investigation or the inducement of others to
fail to cooperate or to produce documents or other materials in connection with such investigation. 

 Notwithstanding
anything to the contrary in the foregoing, any purported termination for Cause under subsections (i), (iii), (iv), (v) or (vii) above shall not be effective unless and until (A) the Company has provided Executive with Notice of Termination
that summarizes the facts and circumstances giving rise to the termination for Cause and (B) to the extent the Executive’s action (or inaction) is curable as determined in the Company’s sole discretion, the Executive has been afforded
an opportunity of not less than fourteen (14) days in which to cure the complained-of action (or inaction) described in the Notice of Termination. 

(d)    Termination by the Company without Cause. The Company may terminate the Executive’s
employment hereunder at any time without Cause. Any termination by the Company of the Executive’s employment under this Agreement which does not constitute a termination for Cause under Section 3(c), does not result from the death of the
Executive under Section 3(a) or does not result from frustration of contract under Section 3(b) shall be deemed a termination without Cause. 

(e)    Termination by the Executive. The Executive may terminate employment hereunder at any time
for any reason, including but not limited to, Good Reason. For purposes of this Agreement, “Good Reason” shall mean that the Executive has completed all steps of the Good Reason Process (hereinafter defined) following the occurrence
of any of the following events without the Executive’s consent (each, a “Good Reason Condition”): 

(i)    a material diminution in the Executive’s responsibilities, authority or duties; 

(ii)    a reduction of twenty percent (20%) or more to the Executive’s Base Salary except for across-the-board salary reductions based on the Company’s financial performance similarly affecting all or substantially all senior management employees of the Company;

 (iii)    a material change in the geographic location at which the Executive provides services to the
Company, such that there is an increase of at least sixty (60) kilometers of driving distance to such location from the Executive’s principal residence as of such change; or 

(iv)    a material breach of this Agreement by the Company. 

  
 5 

 The “Good Reason Process” consists of the following steps: 

(i)    the Executive reasonably determines in good faith that a Good Reason Condition has occurred; 

(ii)    the Executive notifies the Company in writing of the first occurrence of the Good Reason Condition
within ninety (90) days of the first occurrence of such condition; 
 (iii)    the Executive
cooperates in good faith with the Company’s efforts, for a period of 30 days following such notice (the “Cure Period”), to remedy the Good Reason Condition; 

(iv)    notwithstanding such efforts, the Good Reason Condition continues to exist; and 

(v)    the Executive terminates employment within thirty (30) days after the end of the Cure Period.

 If the Company cures the Good Reason Condition during the Cure Period, Good Reason shall be deemed not to have occurred. 

If the Executive’s employment with the Company is terminated for any reason, the Company shall pay or provide to the Executive (or to the
Executive’s authorized representative or estate) (i) any Base Salary earned through the Date of Termination; (ii) unpaid expense reimbursements (subject to, and in accordance with, Section 2(c) of this Agreement); (ii)
accrued but unpaid vacation pay through the Date of Termination and (iii) any vested benefits the Executive may have under any employee benefit plan of the Company through the Date of Termination, which vested benefits shall be paid and/or
provided in accordance with the terms of such employee benefit plans (collectively, the “Accrued Obligations”). 

4.    Notice and Date of Termination. 

(a)    Notice of Termination. Except for termination as specified in Section 3(a), any
termination of the Executive’s employment by the Company or any such termination by the Executive shall be communicated by written Notice of Termination to the other party hereto. For purposes of this Agreement, a “Notice of
Termination” shall mean a notice which shall indicate the specific termination provision (by subsection) in this Agreement relied upon. 

(b)    Date of Termination. “Date of Termination” shall mean: (i) if the
Executive’s employment is terminated by death, the date of death; (ii) if the Executive’s employment is terminated on account of frustration under Section 3(b) the date on which Notice of Termination is given; (iii) if the
Executive’s employment is terminated by the Company for Cause under Section 3(c), and the Company determines that the Executive’s action or inaction is curable, the date which is fourteen (14) days after the date on which the
Notice of Termination is given, and if the Company determines that the Executive’s action or inaction is not curable, or if a cure period is not required under Section 3(c), the date on which the Notice of Termination is given;
(iv) if the Executive’s employment is terminated by the 

  
 6 

 
Company without Cause under Section 3(d), the date on which a Notice of Termination is given or the date otherwise specified by the Company in the Notice of Termination; (v) if the
Executive’s employment is terminated by the Executive under Section 3(e) other than for Good Reason, thirty (30) days after the date on which a Notice of Termination is given; and (vi) if the Executive’s employment is
terminated by the Executive under Section 3(e) for Good Reason, the date on which a Notice of Termination is given after the end of the Cure Period. Notwithstanding the foregoing, in the event that the Executive gives a Notice of Termination to
the Company, the Company may unilaterally relieve the Executive from all or any of the Executive’s duties and powers for such periods and on such terms as it considers expedient and may require that the Executive remain away from all or any of
the Company’s premises . Regardless of whether or not the Company relieves the Executive from all or any of the Executive’s duties or powers or requires the Executive to remain away from the Company’s premises, the Executive will be
paid his Base Salary, and will continue to participate in the Company’s benefit plans, in accordance with this Agreement and these actions shall not result in a termination by the Company for purposes of this Agreement. 

5.    Separation Pay and Benefits Upon Termination by the Company without Cause or by the Executive for Good Reason
Outside the Change in Control Period. If the Executive’s employment is terminated by the Company without Cause as provided in Section 3(d), or the Executive terminates employment for Good Reason as provided in Section 3(e),
each outside of the Change in Control Period (as defined below), then, in addition to the Accrued Obligations: 

(a)    the Company shall pay the Executive an amount equal to twelve (12) months of the
Executive’s Base Salary (the “Separation Amount”) or, if greater, shall provide the Executive with the minimum notice of termination and severance pay (if applicable) required to be provided in accordance with the ESA. The Separation
Amount shall be payable by means of salary continuance; 
 (b)    the Company shall pay any Bonus awarded
in respect of the year preceding the year of termination but not yet paid; 
 (c)    the Company shall
pay to the Executive his Bonus at target for the year in which the Executive’s employment terminates, pro-rated to the Date of Termination; 

(d)    the Company shall pay an amount equal to the Executive’s Bonus calculated at target for the
then-current year; and 
 (e)    the Company shall continue to pay premiums to provide all benefit plans
in effect for senior management of the Company on the Date of Termination until the earlier of (i) twelve (12) months; and (ii) the date on which the Executive secures comparable coverage through alternate employment; provided that, if the
Company cannot continue any particular benefit pursuant to the terms of the relevant plan or policy, then the Company’s obligations shall be limited to the minimum period required pursuant to the ESA. 

(f)    Any amounts payable by the Company to McMaster under the Memorandum of Understanding in respect of
the period following the Date of Termination shall be deducted from any Separation Amount or Accrued Obligations payable (the 

  
 7 

 
“McMaster Termination Payment”). Notwithstanding the McMaster Termination Payment, the Executive will not receive less than the applicable minimum entitlements pursuant to
the ESA in respect of the termination of his employment. 
 6.    Separation Pay and Benefits Upon Termination by the
Company without Cause or by the Executive for Good Reason within the Change in Control Period. The provisions of this Section 6 shall apply in lieu of, and expressly supersede, the provisions of Section 5 if (i) the
Executive’s employment is terminated either (a) by the Company without Cause as provided in Section 3(d), or (b) by the Executive for Good Reason as provided in Section 3(e), and (ii) the Date of Termination is within
twelve (12) months after the occurrence of the first event constituting a Change in Control (such period, the “Change in Control Period”). These provisions shall not apply and be of no further force or effect before or after a Change
in Control Period. 
 (a)    If the Executive’s employment is terminated by the Company without
Cause as provided in Section 3(d) or the Executive terminates employment for Good Reason as provided in Section 3(e) and in each case the Date of Termination occurs during the Change in Control Period, then, in addition to the Accrued
Obligations, and subject to the signing of the Separation Agreement and Release (defined below) by the Executive in consideration of any payments or benefits which exceed the minimum requirements of the ESA and the Separation Agreement and Release
becoming fully effective, all within the time frame set forth in the Separation Agreement and Release: 

(i)    the Company shall provide the Executive an amount equal to eighteen (18) months of the
Executive’s then current Base Salary (or the Executive’s Base Salary in effect immediately prior to the Change in Control, if higher) payable in the most tax effective manner (the “Change in Control Payment”) or, if greater,
shall provide the Executive with the minimum notice of termination and severance pay (if applicable) required to be provided in accordance with the ESA; 

(ii)    the Company shall pay any Bonus awarded in respect of the year preceding the year of termination
but not yet paid; 
 (iii)    the Company shall pay to the Executive his Bonus at target for the year in
which the Executive’s employment terminates, pro-rated to the Date of Termination; 

(iv)    the Company shall pay an amount equal to the Bonus calculated at target for the then-current year
multiplied by one and one-half (1.5); and 
 (v)    the Company
shall continue to pay premiums for benefit plans in effect for senior management of the Company on the Date of Termination until the earlier of (i) the date that is eighteen (18) months from the Date of Termination; and (ii) the date
on which the Executive secures comparable coverage through alternate employment; provided that, if the Company cannot continue any particular benefit pursuant to the terms of the relevant plan or policy, then the Company’s obligations shall be
limited to the minimum period required pursuant to the ESA. 

  
 8 

 (vi)    Notwithstanding anything to the contrary in any
applicable option agreement or other stock-based award agreement, all outstanding time-based stock options and other stock-based awards subject to time-based vesting (the “Time-Based Equity Awards”), excluding the options granted to the
Executive pursuant to the option agreement between the Executive and the Company dated November 23, 2017 (the “Initial Grant”), shall automatically accelerate and become fully vested and exercisable as of the Date of Termination. For
greater certainty, the Initial Grant shall accelerate and become vested and exercisable in the event of a Sale of the Company (as defined in the Equity Documents) in accordance with the Equity Documents. 

The amounts payable under this Section 6(a) shall be paid within sixty (60) days after the Date of Termination. 

The Executive acknowledges and agrees that the Separation Amount, the Change in Control Payment and all other payments and benefits provided pursuant to
Section 5 and Section 6 of this Agreement supersede and replace any and all rights to reasonable notice of termination that the Executive might otherwise be entitled to at common law. The Executive agrees that the payments include
all amounts owing for termination and/or severance pay under any contract, common law, statute (including without limitation the ESA), or otherwise. The Company shall fully comply with the ESA. 

Any payments and benefits provided pursuant to Section 5 and Section 6 of this Agreement that exceed the minimum requirements of the ESA are
conditional on the Executive signing a separation agreement and release in a form and manner satisfactory to the Company, which shall include, without limitation, a general release of claims against the Company and all related persons and entities,
a reaffirmation of all of the Executive’s Continuing Obligations (as defined below), and, in the Company’s sole discretion, a one-year post-employment noncompetition agreement, and shall provide that
if the Executive breaches any of the Continuing Obligations, all payments of the Severance Amount shall immediately cease (the “Separation Agreement and Release”). 

(b)    Definitions. For purposes of this Section 6, the following terms shall have the following meanings:

 “Change in Control” shall have the same meaning as “Sale Event” as set out in the Company’s 2020 Stock Option
and Incentive Plan as follows : (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 common 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. 

  
 9 

 7.    Continuing Obligations.  

(a)    Restrictive Covenants Agreement. As a condition of employment, the Executive is required to enter into the
Employee Confidentiality, Assignment, Nonsolicitation and Noncompetition Agreement, attached hereto as Exhibit A (the “Restrictive Covenants Agreement”). For purposes of this Agreement, the obligations in this Section 7 and
those that arise in the Restrictive Covenants Agreement and any other agreement relating to confidentiality, assignment of inventions, or other restrictive covenants shall collectively be referred to as the “Continuing Obligations.” 

(b)    Third-Party Agreements and Rights. The Executive hereby confirms that the Executive is not
bound by the terms of any agreement with any previous employer or other party which restricts in any way the Executive’s use or disclosure of information, other than confidentiality restrictions (if any), or the Executive’s engagement in
any business. The Executive represents to the Company that the Executive’s execution of this Agreement, the Executive’s employment with the Company and the performance of the Executive’s proposed duties for the Company will not
violate any obligations the Executive may have to any such previous employer or other party. In the Executive’s work for the Company, the Executive will not disclose or make use of any information in violation of any agreements with or rights
of any such previous employer or other party, and the Executive will not bring to the premises of the Company any copies or other tangible embodiments of non-public information belonging to or obtained from
any such previous employment or other party. 
 (c)    Litigation and Regulatory Cooperation. During and after
the Executive’s employment, the Executive shall cooperate fully with the Company in (i) the defense or prosecution of any claims or actions now in existence or which may be brought in the future against or on behalf of the Company which
relate to events or occurrences that transpired while the Executive was employed by the Company, and (ii) the investigation, whether internal or external, of any matters about which the Company believes the Executive may have knowledge or
information. The Executive’s full cooperation in connection with such claims, actions or investigations shall include, but not be limited to, being available to meet with counsel to answer questions or to prepare for discovery or trial and to
act as a witness on behalf of the Company at mutually convenient times. During and after the Executive’s employment, the Executive also shall cooperate fully with the Company in connection with any investigation or review of any federal, state,
provincial or local regulatory authority as any such investigation or review relates to events or occurrences that transpired while the Executive was employed by the Company. The Company shall reimburse the Executive for any reasonable out-of-pocket expenses incurred in connection with such cooperation, and will compensate the Executive at an hourly rate for all time spent on such matters based on the
Executive’s Base Salary on the Date of Termination. 

(d)    Non-Disparagement. During the Executive’s employment and
following the termination of the Executive’s employment for any reason, the Executive shall not, and will not cause any third party to, publish or communicate to any person, any Disparaging remarks, comments or statements concerning the
Company, its affiliated and related entities, and its and 

  
 10 

 
their present and former members, partners, directors, officers, shareholders, employees, agents, legal counsel, successors and assigns. For purposes of this Agreement, “Disparaging”
shall mean remarks, comments or statements that place the person or entity being disparaged in a false or negative light or that otherwise impugn the character, honesty, integrity, morality, acumen, abilities, conduct or operations of the person or
entity being disparaged. On or following the Executive’s Date of Termination, the Company shall instruct its then current executive officers and then current directors not to make Disparaging remarks, comments or statements about the Executive
during the then current executive officers and then current directors’ employment and/or engagement with the Company; provided, however, that the foregoing does not in any way limit or modify an officer or director’s obligations or duties
(fiduciary or otherwise) to any person. Notwithstanding anything to the contrary in the foregoing, nothing in this Agreement shall be construed to: (i) preclude truthful disclosures in response to lawful process as required by applicable law,
regulation, or order or directive of a court, governmental agency or regulatory organization; or (ii) prevent the Executive, the Company, or any other person from making truthful statements as may be reasonably required to perform such
person’s duties and responsibilities on behalf of the Company, such as (for example) offering negative performance feedback in a personnel review. 

(e)    Relief. The Executive agrees that it would be difficult to measure any damages caused to the
Company which might result from any breach by the Executive of the Continuing Obligations, and that in any event money damages would be an inadequate remedy for any such breach. Accordingly, the Executive agrees that if the Executive
breaches, or proposes to breach, any portion of the Continuing Obligations, the Company shall be entitled, in addition to all other remedies that it may have, to an injunction or other appropriate equitable relief to restrain any such breach without
showing or proving any actual damage to the Company and without the posting of a bond. 
 8.    Governing Law and
Absence of Claims. This Agreement is a contract made under and shall be governed by and construed in accordance with, the laws of the Province of Ontario and the federal laws of Canada applicable in the Province of Ontario. In exchange for good
and sufficient consideration, including the retention bonus, the Executive agrees that he has no claims against the Company in respect of his employment prior to the date this Agreement is executed, whether under common law, contract or statute,
including the ESA and human rights legislation, and that by signing below, the Executive fully an finally releases all such claims. 

9.    ESA Failsafe. It is the intention of the Executive and the Company to comply with the ESA. Accordingly, this
Agreement shall (a) not be interpreted as in any way waiving or contracting out of the ESA, and (b) be interpreted to achieve compliance with the ESA. This Agreement contains the parties mutual understanding and there shall be no
presumption of strict interpretation against either party. It is understood and agreed that all provisions of this Agreement are subject to all applicable minimum requirements under the ESA. In the event that the ESA provides for superior
entitlements upon termination of employment or otherwise (“statutory entitlements”) than provided for under this Agreement, the Company shall provide the Executive with his statutory entitlements in substitution for the Executive’s
rights under this Agreement. 

  
 11 

 10.    Waiver of Jury Trial. Each of the Executive and the
Company irrevocably and unconditionally WAIVES ALL RIGHT TO TRIAL BY JURY IN ANY PROCEEDING (WHETHER BASED ON CONTRACT, TORT OR OTHERWISE) ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE EXECUTIVE’S EMPLOYMENT BY THE COMPANY OR ANY
AFFILIATE OF THE COMPANY, INCLUDING WITHOUT LIMITATION THE EXECUTIVE’S OR THE COMPANY’S PERFORMANCE UNDER, OR THE ENFORCEMENT OF, THIS AGREEMENT. 

11.    Integration. This Agreement constitutes the entire agreement between the parties with respect to the subject
matter hereof and supersedes all prior agreements between the parties concerning such subject matter, including the Prior Agreement, provided that the Continuing Obligations, Restrictive Covenants Agreement and the Equity Documents unless otherwise
modified herein remain in full force and effect. 
 12.    Withholding; Tax Effect and Currency. The Company may
withhold from any amounts payable by the Company to the Executive such federal, provincial or other taxes as are required to be withheld pursuant to any applicable law or regulation and subject to any deductions or customary contributions to the
cost of employee benefits, if any. Nothing in this Agreement shall be construed to require the Company to make any payments to compensate the Executive for any adverse tax effect associated with any payments or benefits or for any deduction or
withholding from any payment or benefit. Unless otherwise specified, all references to amounts in or contemplated by this Agreement are to the lawful currency of Canada. 

13.    Assignment. Neither the Executive nor the Company may make any assignment of this Agreement or any interest
in it, by operation of law or otherwise, without the prior written consent of the other; provided, however, that the Company may assign its rights and obligations under this Agreement (including the Restrictive Covenants Agreement) without the
Executive’s consent to any affiliate or to any person or entity with whom the Company shall hereafter effect a reorganization, consolidate with, or merge into or to whom it transfers all or substantially all of its properties or assets;
provided further that if the Executive remains employed or becomes employed by the Company, the purchaser or any of their affiliates in connection with any such transaction, then the Executive shall not be entitled to any payments, benefits or
vesting pursuant to Section 5 and/or pursuant to Section 6 of this Agreement solely as a result of such transaction. This Agreement shall inure to the benefit of and be binding upon the Executive and the Company, and each of the
Executive’s and the Company’s respective successors, executors, administrators, heirs and permitted assigns. 

14.    Enforceability. If, in any jurisdiction, any portion or provision of this Agreement or its application to
either party or circumstance is restricted, prohibited or unenforceable, the provision shall, as to that jurisdiction, be ineffective only to the extent of the restriction, prohibition or unenforceability without invalidating the remaining portion
or provisions of this Agreement and without affecting the validity or enforceability of such provision in any other jurisdiction, or without affecting its application to other parties or circumstances 

15.    Survival. The provisions of this Agreement shall survive the termination of this Agreement and/or the
termination of the Executive’s employment to the extent necessary to effectuate the terms contained herein. 

  
 12 

 16.    Waiver. No waiver of any provision hereof shall be
effective unless made in writing and signed by the waiving party. The failure of any party to require the performance of any term or obligation of this Agreement, or the waiver by any party of any breach of this Agreement, shall not prevent any
subsequent enforcement of such term or obligation or be deemed a waiver of any subsequent breach. 

17.    Notices. Any notices, requests, demands and other communications provided for by this Agreement shall be
sufficient if in writing and delivered in person or sent by a nationally recognized overnight courier service or by registered or certified mail, postage prepaid, return receipt requested, to the Executive at the last address the Executive has filed
in writing with the Company or, in the case of the Company, at its main offices, attention of the Board. 

18.    Amendment. This Agreement may be amended or modified only by a written instrument signed by the Executive
and by a duly authorized representative of the Company. 
 19.    Effect on Other Plans and Agreements. An
election by the Executive to resign for Good Reason under the provisions of this Agreement shall not be deemed a voluntary termination of employment by the Executive for the purpose of interpreting the provisions of any of the Company’s benefit
plans, programs or policies. Nothing in this Agreement shall be construed to limit the rights of the Executive under the Company’s benefit plans, programs or policies except as otherwise provided herein and except that the Executive shall have
no rights to any severance benefits under any Company severance pay plan, offer letter or otherwise. Except for the Restrictive Covenants Agreement, in the event that the Executive is party to an agreement with the Company providing for payments or
benefits under such plan or agreement and under this Agreement, the terms of this Agreement shall govern and the Executive may receive payment under this Agreement only and not both. Further, Section 5 and Section 6 of this Agreement are
mutually exclusive and in no event shall the Executive be entitled to payments or benefits pursuant to both Section 5 and Section 6 of this Agreement. 

20.    Counterparts. This Agreement may be executed in any number of counterparts, each of which when so executed
and delivered shall be taken to be an original; but such counterparts shall together constitute one and the same document. 

21.    Legal Fees. The Company will reimburse the Executive up to $5000, inclusive of applicable taxes, in respect
of legal fees incurred by him in connection with the review and execution of this Agreement. The payment will be made directly to the firm retained by the Executive upon submission to the Company of any invoice reflecting the total amount due. 

  
 13 

 IN WITNESS WHEREOF, the parties have executed this Agreement effective on the Effective
Date. 
  

			
	FUSION PHARMACEUTICALS, INC.

 
			
		
	By:	 	  

	Its:	 	  

 
			
	
	EXECUTIVE
	
	  

	John Valliant

  

  
 14 

 Exhibit A 

Restrictive Covenants Agreement

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