Sec Form 4 Filing - Leamon Christopher P @ Fusion Pharmaceuticals Inc. - 2024-06-04

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Leamon Christopher P 2. Issuer Name and Ticker or Trading Symbol Fusion Pharmaceuticals Inc. [ FUSN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Scientific Officer (Last) (First) (Middle) C/O FUSION PHARMACEUTICALS INC., TWO INTERNATIONAL PLACE, SUITE 2310 3. Date of Earliest Transaction (MM/DD/YY) 06/04/2024 (Street) BOSTON, MA02110 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 06/04/2024 D 11,957 D 0 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Option (Right to Buy) $ 7.09 06/04/2024 D 218,000 ( 2 ) ( 2 ) Common Stock 218,000 ( 2 ) 0 D Stock Option (Right to Buy) $ 3.75 06/04/2024 D 250,000 ( 2 ) ( 2 ) Common Stock 250,000 ( 2 ) 0 D Stock Option (Right to Buy) $ 8.44 06/04/2024 D 106,100 ( 2 ) ( 2 ) Common Stock 106,100 ( 2 ) 0 D Restricted Stock Units ( 3 ) 06/04/2024 D 63,700 ( 4 ) ( 4 ) Common Stock 63,700 ( 4 ) 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Leamon Christopher P C/O FUSION PHARMACEUTICALS INC. TWO INTERNATIONAL PLACE, SUITE 2310 BOSTON, MA02110 Chief Scientific Officer Signatures /s/ Maria Stahl as Attorney-in-Fact for Christopher Leamon 06/04/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Pursuant to the Arrangement Agreement, dated as of March 18, 2024 (the "Arrangement Agreement"), by and among the Issuer, AstraZeneca AB, a public company with limited liability (Aktiebolag) incorporated under the laws of Sweden ("Parent") and 15863210 Canada Inc., a corporation formed under the Canada Business Corporations Act ("Purchaser"), Purchaser acquired all of the issued and outstanding common shares of the Issuer (collectively, the "Shares") effective as of 12:01 a.m. Toronto time on June 4, 2024 (the "Effective Time"). Following the Effective Time, each Share outstanding immediately prior to the Effective Time was assigned and transferred by the holder thereof to Purchaser in exchange for (i) US$21.00 in cash (the "Cash Consideration") plus (ii) one contingent value right (each, a "CVR") representing the contingent right to receive a cash payment equal to US$3.00, in each case subject to applicable tax withholdings and other source deductions. ( 2 )Pursuant to the terms of the Arrangement Agreement, immediately following the Effective Time, each option to purchase Shares granted (each, an "Option") with an exercise price that is less than the Cash Consideration and outstanding immediately prior to the Effective Time, whether vested or unvested, was assigned, transferred and surrendered by the holder thereof to the Issuer and thereafter cancelled in consideration for (A) a cash payment by or on behalf of the Issuer equal to the number of Shares into which such Option is then exercisable multiplied by the amount, if any, by which the Cash Consideration exceeds the exercise price per Share of such Option and (B) one CVR with respect to each Share into which such Option is then exercisable, in each case subject to applicable tax withholdings and other source deductions. ( 3 )Each restricted stock unit ("RSU") represents a contingent right to receive one Share. ( 4 )Pursuant to the terms of the Arrangement Agreement, immediately following the Effective Time, each RSU, whether vested or unvested, was assigned, transferred and surrendered by the holder thereof to the Issuer and thereafter cancelled in consideration for, (i) if held by a Canadian Incentive Holder (as defined in the Arrangement Agreement), the number of Shares underlying such RSU and (ii) if held by a Non-Canadian Incentive Holder (as defined in the Arrangement Agreement), (A) a cash payment by or on behalf of the Issuer equal to the number of Shares underlying such RSU multiplied by the amount, if any, by the Cash Consideration and (B) one CVR with respect to each Share underlying such RSU, in each case subject to applicable tax withholdings and other source deductions.

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