X0306 4 2020-06-25 0 0001805890 Fusion Pharmaceuticals Inc. FUSN 0001488771 Christenson Johan C/O FUSION PHARMACEUTICALS INC. 270 LONGWOOD ROAD SOUTH HAMILTON A6 L8P 0A6 ONTARIO, CANADA 1 0 0 0 Warrants to purchase Class B Preferred Exchangeable Shares 1.1514 2020-01-10 4 A 0 576233 0.00 A 2020-01-10 2022-01-10 Common Shares 107929 576233 I See Footnote Class B Preferred Exchangeable Shares 2020-06-02 4 P 0 2856108 1.1514 A Common Shares 534951 5712216 I See Footnote Stock Option (Right to Buy) 17.00 2020-06-25 4 A 0 30000 0.00 A 2030-06-18 Common Shares 30000 30000 D Represents Warrants to Purchase Class B Preferred Exchangeable Shares of Fusion Pharmaceuticals (Ireland) Limited. Upon the closing of the Issuer's initial public offering, the Warrants to purchase Class B Preferred Exchangeable Shares of Fusion Pharmaceuticals (Ireland) Limited will become warrants to purchase Common Shares of the Issuer at an exercise price of $8.10 per share. The securities are held directly by HealthCap VII, L.P. ("HCLP"). HealthCap VII GP SA ("HCSA") is the sole general partner of HCLP and has voting and investment control over the Shares and Preferred Stock held by HCLP. The reporting person has an indirect interest in HCSA and is an employee of HealthCap VII Advisor AB. The reporting person disclaims beneficial ownership of Shares and Preferred Stock held by HCLP except to the extent of any pecuniary interest therein. Represents Class B Preferred Exchangeable Shares of Fusion (Pharmaceuticals) Ireland Limited. The Class B Preferred Exchangeable Shares of Fusion Pharmaceuticals (Ireland) Limited are redeemable into Class B Preferred Shares of the Issuer. Upon the closing of the Issuer's initial public offering, the Class B Preferred Exchangeable Shares of Fusion Pharmaceuticals (Ireland) Limited will be redeemed into Class B Preferred Shares on a one-for-one basis, which will subsequently convert on a one-for-5.339 basis into the number of Common Shares shown in column 7. The Class B Preferred Exchangeable Shares have no expiration date. This option shall vest and become exercisable in 36 equal monthly installments commencing on July 18, 2020. /s/ John Crowley, Attorney-in-Fact 2020-06-29