X0306 4 2020-06-25 0 0001805890 Fusion Pharmaceuticals Inc. FUSN 0001587972 Crowley John J C/O FUSION PHARMACEUTICALS INC. 270 LONGWOOD ROAD SOUTH HAMILTON A6 L8P 0A6 ONTARIO, CANADA 0 1 0 0 Chief Financial Officer Stock Option (Right to Buy) 2.99 2020-02-06 4 A 0 38561 0.00 A 2030-01-10 Non-Voting Common Shares 38561 38561 D Stock Option (Right to Buy) 17.00 2020-06-25 4 A 0 26972 0.00 A 2030-06-18 Common Shares 26972 26972 D Stock Option (Right to Buy) 17.00 2020-06-25 4 A 0 60852 0.00 A 2030-06-25 Common Shares 60852 60852 D 25% of the shares subject to this option shall vest and become exercisable on January 10, 2021, with the remainder vesting in 36 substantially equal monthly installments thereafter. Prior to closing of the Issuer's initial public offering, such Non-Voting Common Shares will convert into Voting Common Shares and subsequently into Common Shares on a one-for-one basis. 25% of the shares subject to this option shall vest and become exercisable on June 18, 2021, with the remainder vesting in 36 substantially equal monthly installments thereafter. 25% of the shares subject to this option shall vest and become exercisable on June 25, 2021, with the remainder vesting in 36 substantially equal monthly installments thereafter. /s/ John Crowley 2020-06-29