MPM BioVentures 2014, L.P.

SEC source: 0000899243-20-020691 · doc4.xml · derivative · entry 24

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 15,820 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.exercise_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.expiration_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.expiration_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.expiration_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · derivative.underlying_shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · derivative.underlying_shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.underlying_shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.underlying_shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F6 · ownership.nature: MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("2018 BV LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). Luke Evnin, Ansbert Gadicke, Todd Foley and Edward Hurwitz are the managing directors of 2018 BV LLC and members of MPM Asset Management Investors BV2018 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · derivative · entry 23

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 42,605 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.exercise_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.expiration_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.expiration_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.expiration_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · derivative.underlying_shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · derivative.underlying_shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.underlying_shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.underlying_shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F6 · ownership.nature: MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("2018 BV LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). Luke Evnin, Ansbert Gadicke, Todd Foley and Edward Hurwitz are the managing directors of 2018 BV LLC and members of MPM Asset Management Investors BV2018 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · derivative · entry 22

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 801,619 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.exercise_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.expiration_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.expiration_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.expiration_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · derivative.underlying_shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · derivative.underlying_shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.underlying_shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.underlying_shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F6 · ownership.nature: MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("2018 BV LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). Luke Evnin, Ansbert Gadicke, Todd Foley and Edward Hurwitz are the managing directors of 2018 BV LLC and members of MPM Asset Management Investors BV2018 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · derivative · entry 21

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 43,687 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.exercise_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.expiration_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.expiration_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.expiration_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · derivative.underlying_shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · derivative.underlying_shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.underlying_shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.underlying_shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F5 · ownership.nature: MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("2014 BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of 2014 BV LLC and members of MPM Asset Management Investors BV2014 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · derivative · entry 20

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 84,655 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.exercise_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.expiration_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.expiration_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.expiration_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · derivative.underlying_shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · derivative.underlying_shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.underlying_shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.underlying_shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F5 · ownership.nature: MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("2014 BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of 2014 BV LLC and members of MPM Asset Management Investors BV2014 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · derivative · entry 19

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 1,269,230 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.exercise_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.exercise_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.exercise_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · derivative.expiration_date: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.expiration_date: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.expiration_date: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F1 · derivative.underlying_shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · derivative.underlying_shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · derivative.underlying_shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · derivative.underlying_shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F5 · ownership.nature: MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("2014 BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of 2014 BV LLC and members of MPM Asset Management Investors BV2014 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 18

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 25,974

F13 · shares: On July 28, 2020, MPM Asset Management Investors BV 2018 LLC purchased 1,121 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F13 · ownership.nature: On July 28, 2020, MPM Asset Management Investors BV 2018 LLC purchased 1,121 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 17

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 69,951

F12 · shares: On July 28, 2020, BV 2018(B) purchased 3,020 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F12 · ownership.nature: On July 28, 2020, BV 2018(B) purchased 3,020 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 16

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 1,316,139

F11 · shares: On July 28, 2020, BV 2018 purchased 56,814 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F11 · ownership.nature: On July 28, 2020, BV 2018 purchased 56,814 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 15

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 71,727

F10 · shares: On July 28, 2020, MPM Asset Management Investors BV 2014 LLC purchased 3,096 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F10 · ownership.nature: On July 28, 2020, MPM Asset Management Investors BV 2014 LLC purchased 3,096 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 14

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 138,985

F9 · shares: On July 28, 2020, BV 2014(B) purchased 5,994 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F9 · ownership.nature: On July 28, 2020, BV 2014(B) purchased 5,994 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 13

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,083,887

F8 · shares: On July 28, 2020, BV 2014 purchased 89,955 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F8 · ownership.nature: On July 28, 2020, BV 2014 purchased 89,955 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 12

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 24,853

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F12 · shares: On July 28, 2020, BV 2018(B) purchased 3,020 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F6 · ownership.nature: MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("2018 BV LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). Luke Evnin, Ansbert Gadicke, Todd Foley and Edward Hurwitz are the managing directors of 2018 BV LLC and members of MPM Asset Management Investors BV2018 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 11

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 66,931

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F12 · shares: On July 28, 2020, BV 2018(B) purchased 3,020 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F6 · ownership.nature: MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("2018 BV LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). Luke Evnin, Ansbert Gadicke, Todd Foley and Edward Hurwitz are the managing directors of 2018 BV LLC and members of MPM Asset Management Investors BV2018 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 10

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 1,259,325

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F12 · shares: On July 28, 2020, BV 2018(B) purchased 3,020 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F6 · ownership.nature: MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("2018 BV LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). Luke Evnin, Ansbert Gadicke, Todd Foley and Edward Hurwitz are the managing directors of 2018 BV LLC and members of MPM Asset Management Investors BV2018 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 9

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 68,381

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F12 · shares: On July 28, 2020, BV 2018(B) purchased 3,020 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F5 · ownership.nature: MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("2014 BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of 2014 BV LLC and members of MPM Asset Management Investors BV2014 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 8

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 132,991

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F12 · shares: On July 28, 2020, BV 2018(B) purchased 3,020 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F5 · ownership.nature: MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("2014 BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of 2014 BV LLC and members of MPM Asset Management Investors BV2014 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 7

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 1,993,932

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F12 · shares: On July 28, 2020, BV 2018(B) purchased 3,020 shares of Common Stock of the Issuer at a price of $19.00 per share pursuant to an underwritten public offering.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F5 · ownership.nature: MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("2014 BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of 2014 BV LLC and members of MPM Asset Management Investors BV2014 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 6

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 15,820

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F6 · ownership.nature: MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("2018 BV LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). Luke Evnin, Ansbert Gadicke, Todd Foley and Edward Hurwitz are the managing directors of 2018 BV LLC and members of MPM Asset Management Investors BV2018 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 5

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 42,605

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F6 · ownership.nature: MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("2018 BV LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). Luke Evnin, Ansbert Gadicke, Todd Foley and Edward Hurwitz are the managing directors of 2018 BV LLC and members of MPM Asset Management Investors BV2018 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 4

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 801,619

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F6 · ownership.nature: MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("2018 BV LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). Luke Evnin, Ansbert Gadicke, Todd Foley and Edward Hurwitz are the managing directors of 2018 BV LLC and members of MPM Asset Management Investors BV2018 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 3

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 43,687

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F5 · ownership.nature: MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("2014 BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of 2014 BV LLC and members of MPM Asset Management Investors BV2014 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 2

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 84,655

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F5 · ownership.nature: MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("2014 BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of 2014 BV LLC and members of MPM Asset Management Investors BV2014 LLC.

SEC source: 0000899243-20-020691 · doc4.xml · nonDerivative · entry 1

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM BioVentures 2018 LLC · CIK 0001818702 · 10% owner

MPM BioVentures 2018 GP LLC · CIK 0001818701 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 1,269,230

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · shares: Each share of Series B Convertible Preferred stock is convertible at any time, at the Reporting Person's election, into Common Stock, based on the then-applicable conversion rate and has no expiration date. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F2 · shares: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · shares: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · shares: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F2 · price: The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 LP ("BV 2014") will convert automatically into 1,269,230 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2014 (B) LP ("BV 2014(B)") will convert automatically into 84,655 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 43,687 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 LP ("BV 2018") will convert automatically into 801,619 shares of Common Stock upon the closing of the Issuer's initial public offering.

F3 · price: (Continued From footnote 2) The shares of Series B Convertible Preferred stock held by MPM BioVentures 2018 (B) LP ("BV 2018(B)") will convert automatically into 42,605 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 15,820 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014 will convert automatically into 724,702 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2014(B) will convert automatically into 48,336 shares of Common Stock upon the closing of the Issuer's initial public offering.

F4 · price: (Continued From footnote 3) The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2014 LLC will convert automatically into 24,944 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018 will convert automatically into 457,706 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by BV 2018(B) will convert automatically into 24,326 shares of Common Stock upon the closing of the Issuer's initial public offering. The shares of Series B-2 Convertible Preferred stock held by MPM Asset Management Investors BV 2018 LLC will convert automatically into 9,033 shares of Common Stock upon the closing of the Issuer's initial public offering. These amounts reflect a 1-for-3.3115 reverse stock split which became effective on July 20, 2020.

F5 · ownership.nature: MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("2014 BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of 2014 BV LLC and members of MPM Asset Management Investors BV2014 LLC.

SEC source: 0001209191-20-038917 · doc4.xml · derivative · entry 5

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

EVNIN LUKE · CIK 0001134657 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Shares · 952,191 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: All series of convertible preferred shares converted into the number of shares of the Issuer's common shares on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.exercise_date: All series of convertible preferred shares converted into the number of shares of the Issuer's common shares on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.expiration_date: All series of convertible preferred shares converted into the number of shares of the Issuer's common shares on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F7 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-20-038917 · doc4.xml · derivative · entry 4

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

EVNIN LUKE · CIK 0001134657 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Shares · 1,801,581 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: All series of convertible preferred shares converted into the number of shares of the Issuer's common shares on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.exercise_date: All series of convertible preferred shares converted into the number of shares of the Issuer's common shares on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.expiration_date: All series of convertible preferred shares converted into the number of shares of the Issuer's common shares on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F7 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-20-038917 · doc4.xml · nonDerivative · entry 3

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

EVNIN LUKE · CIK 0001134657 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 3,003,772

F5 · shares: The shares were purchased as follows: 227,042 by BV 2014, 15,143 by BV 2014(B) and 7,815 by AM BV2014.

F3 · ownership.nature: The Reporting Persons disclaim beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.

F6 · ownership.nature: The shares are held as follows: 2,727,927 by BV 2014, 181,948 by BV 2014(B) and 93,897 by AM BV2014.

SEC source: 0001209191-20-038917 · doc4.xml · nonDerivative · entry 2

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

EVNIN LUKE · CIK 0001134657 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,753,772

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: All series of convertible preferred shares converted into the number of shares of the Issuer's common shares on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F3 · ownership.nature: The Reporting Persons disclaim beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.

F4 · ownership.nature: The shares are held as follows: 2,500,885 by BV 2014, 166,805 by BV 2014(B) and 86,082 by AM BV2014.

SEC source: 0001209191-20-038917 · doc4.xml · nonDerivative · entry 1

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

EVNIN LUKE · CIK 0001134657 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 1,801,581

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: All series of convertible preferred shares converted into the number of shares of the Issuer's common shares on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F2 · ownership.nature: The shares are held as follows: 1,636,136 by MPM BioVentures 2014, L.P. ("BV 2014"), 109,128 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)") and 56,317 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"). MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of BV LLC and members of AM BV2014.

F3 · ownership.nature: The Reporting Persons disclaim beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.

SEC source: 0001209191-19-012243 · doc4.xml · derivative · entry 5

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

EVNIN LUKE · CIK 0001134657 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 322,901 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: All shares of Series A Preferred Stock and Series B Preferred Stock automatically converted into the number of shares of the Issuer's common stock on a 6.1938:1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.exercise_date: All shares of Series A Preferred Stock and Series B Preferred Stock automatically converted into the number of shares of the Issuer's common stock on a 6.1938:1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.expiration_date: All shares of Series A Preferred Stock and Series B Preferred Stock automatically converted into the number of shares of the Issuer's common stock on a 6.1938:1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F6 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-012243 · doc4.xml · derivative · entry 4

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

EVNIN LUKE · CIK 0001134657 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 2,825,396 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: All shares of Series A Preferred Stock and Series B Preferred Stock automatically converted into the number of shares of the Issuer's common stock on a 6.1938:1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.exercise_date: All shares of Series A Preferred Stock and Series B Preferred Stock automatically converted into the number of shares of the Issuer's common stock on a 6.1938:1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.expiration_date: All shares of Series A Preferred Stock and Series B Preferred Stock automatically converted into the number of shares of the Issuer's common stock on a 6.1938:1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F6 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-012243 · doc4.xml · nonDerivative · entry 3

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

EVNIN LUKE · CIK 0001134657 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 4,050,865

F2 · ownership.nature: The Reporting Persons disclaim beneficial ownership of the securities except to the extent of their respective pecuniary interests therein.

F5 · ownership.nature: The shares are held as follows: 3,056,272 by BV 2014, 203,846 by BV 2014(B), 110,859 by AM BV2014, 195,902 by AM LLC, 421,070 by MPM SunStates and 62,916 by AM SunStates.

SEC source: 0001209191-19-012243 · doc4.xml · nonDerivative · entry 2

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

EVNIN LUKE · CIK 0001134657 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 3,344,199

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: All shares of Series A Preferred Stock and Series B Preferred Stock automatically converted into the number of shares of the Issuer's common stock on a 6.1938:1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F2 · ownership.nature: The Reporting Persons disclaim beneficial ownership of the securities except to the extent of their respective pecuniary interests therein.

F4 · ownership.nature: The shares are held as follows: 2,451,844 by BV 2014, 163,532 by BV 2014(B), 88,935 by AM BV2014, 195,902 by AM LLC, 386,270 by MPM SunStates and 57,716 by AM SunStates.

SEC source: 0001209191-19-012243 · doc4.xml · nonDerivative · entry 1

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

EVNIN LUKE · CIK 0001134657 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 3,021,298

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: All shares of Series A Preferred Stock and Series B Preferred Stock automatically converted into the number of shares of the Issuer's common stock on a 6.1938:1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F2 · ownership.nature: The Reporting Persons disclaim beneficial ownership of the securities except to the extent of their respective pecuniary interests therein.

F3 · ownership.nature: The shares are held as follows: 2,195,681 by MPM BioVentures 2014, L.P. ("BV 2014"), 146,447 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 79,644 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 195,902 by MPM Asset Management LLC ("AM LLC"), 351,155 by MPM SunStates Fund, L.P. ("MPM SunStates") and 52,469 by MPM Asset Management Investors Sunstates Fund LLC ("AM SunStates"). MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). MPM SunStates Fund GP LLC and MPM SunStates GP Managing Member LLC ("SunStates GP") are the direct and indirect general partners of MPM SunStates. Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of BV LLC, Ansbert Gadicke is a member of SunStates GP and Luke Evnin and Anbsert Gadicke are the members of AM LLC.

SEC source: 0001209191-19-010312 · doc4.xml · derivative · entry 15

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 50,837 shares

Expires 2027-01-10

F6 · kind: On February 12, 2019, BV 2014, BV 2014(B) and AM BV2014 exercised warrants to purchase an aggregate of 432,119 shares of the Issuer's common stock for $0.0492 per share. The warrants were exercised as follows: 391,784 by BV 2014, 26,129 by BV 2014(B) and 14,206 by AM BV2014. The exercise price was paid on a cashless basis, resulting in the Issuer's withholding of an aggregate of 1,524 of the warrant shares to pay the exercise price and issuing to the respective Reporting Persons the remaining 430,595 shares.

F10 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-010312 · doc4.xml · derivative · entry 14

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 76,256 shares

Expires 2026-11-01

F6 · kind: On February 12, 2019, BV 2014, BV 2014(B) and AM BV2014 exercised warrants to purchase an aggregate of 432,119 shares of the Issuer's common stock for $0.0492 per share. The warrants were exercised as follows: 391,784 by BV 2014, 26,129 by BV 2014(B) and 14,206 by AM BV2014. The exercise price was paid on a cashless basis, resulting in the Issuer's withholding of an aggregate of 1,524 of the warrant shares to pay the exercise price and issuing to the respective Reporting Persons the remaining 430,595 shares.

F10 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-010312 · doc4.xml · derivative · entry 13

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 50,837 shares

Expires 2025-12-16

F6 · kind: On February 12, 2019, BV 2014, BV 2014(B) and AM BV2014 exercised warrants to purchase an aggregate of 432,119 shares of the Issuer's common stock for $0.0492 per share. The warrants were exercised as follows: 391,784 by BV 2014, 26,129 by BV 2014(B) and 14,206 by AM BV2014. The exercise price was paid on a cashless basis, resulting in the Issuer's withholding of an aggregate of 1,524 of the warrant shares to pay the exercise price and issuing to the respective Reporting Persons the remaining 430,595 shares.

F10 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-010312 · doc4.xml · derivative · entry 12

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 171,579 shares

Expires 2025-08-19

F6 · kind: On February 12, 2019, BV 2014, BV 2014(B) and AM BV2014 exercised warrants to purchase an aggregate of 432,119 shares of the Issuer's common stock for $0.0492 per share. The warrants were exercised as follows: 391,784 by BV 2014, 26,129 by BV 2014(B) and 14,206 by AM BV2014. The exercise price was paid on a cashless basis, resulting in the Issuer's withholding of an aggregate of 1,524 of the warrant shares to pay the exercise price and issuing to the respective Reporting Persons the remaining 430,595 shares.

F10 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-010312 · doc4.xml · derivative · entry 11

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 57,192 shares

Expires 2025-07-23

F6 · kind: On February 12, 2019, BV 2014, BV 2014(B) and AM BV2014 exercised warrants to purchase an aggregate of 432,119 shares of the Issuer's common stock for $0.0492 per share. The warrants were exercised as follows: 391,784 by BV 2014, 26,129 by BV 2014(B) and 14,206 by AM BV2014. The exercise price was paid on a cashless basis, resulting in the Issuer's withholding of an aggregate of 1,524 of the warrant shares to pay the exercise price and issuing to the respective Reporting Persons the remaining 430,595 shares.

F10 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-010312 · doc4.xml · derivative · entry 10

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 25,418 shares

Expires 2025-03-24

F6 · kind: On February 12, 2019, BV 2014, BV 2014(B) and AM BV2014 exercised warrants to purchase an aggregate of 432,119 shares of the Issuer's common stock for $0.0492 per share. The warrants were exercised as follows: 391,784 by BV 2014, 26,129 by BV 2014(B) and 14,206 by AM BV2014. The exercise price was paid on a cashless basis, resulting in the Issuer's withholding of an aggregate of 1,524 of the warrant shares to pay the exercise price and issuing to the respective Reporting Persons the remaining 430,595 shares.

F10 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-010312 · doc4.xml · derivative · entry 9

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 417,852 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.exercise_date: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.expiration_date: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F10 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-010312 · doc4.xml · derivative · entry 8

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 1,578,751 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.exercise_date: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.expiration_date: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F10 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-010312 · doc4.xml · derivative · entry 7

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 1,525,164 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.exercise_date: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F1 · derivative.expiration_date: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F10 · ownership.nature: No securities held by the Reporting Persons.

SEC source: 0001209191-19-010312 · doc4.xml · nonDerivative · entry 6

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 4,524,425

F3 · ownership.nature: Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F9 · ownership.nature: The shares are held as follows: 3,810,051 by BV 2014, 254,116 by BV 2014(B), 138,195 by AM BV2014 and 322,063 by MPM LLC.

SEC source: 0001209191-19-010312 · doc4.xml · nonDerivative · entry 5

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 4,274,425

F6 · kind: On February 12, 2019, BV 2014, BV 2014(B) and AM BV2014 exercised warrants to purchase an aggregate of 432,119 shares of the Issuer's common stock for $0.0492 per share. The warrants were exercised as follows: 391,784 by BV 2014, 26,129 by BV 2014(B) and 14,206 by AM BV2014. The exercise price was paid on a cashless basis, resulting in the Issuer's withholding of an aggregate of 1,524 of the warrant shares to pay the exercise price and issuing to the respective Reporting Persons the remaining 430,595 shares.

F3 · ownership.nature: Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F8 · ownership.nature: The shares are held as follows: 3,583,391 by BV 2014, 238,998 by BV 2014(B), 129,973 by AM BV2014 and 322,063 by MPM LLC.

SEC source: 0001209191-19-010312 · doc4.xml · nonDerivative · entry 4

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 4,275,949

F6 · kind: On February 12, 2019, BV 2014, BV 2014(B) and AM BV2014 exercised warrants to purchase an aggregate of 432,119 shares of the Issuer's common stock for $0.0492 per share. The warrants were exercised as follows: 391,784 by BV 2014, 26,129 by BV 2014(B) and 14,206 by AM BV2014. The exercise price was paid on a cashless basis, resulting in the Issuer's withholding of an aggregate of 1,524 of the warrant shares to pay the exercise price and issuing to the respective Reporting Persons the remaining 430,595 shares.

F3 · ownership.nature: Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F7 · ownership.nature: The shares are held as follows: 3,584,769 by BV 2014, 239,093 by BV 2014(B), 130,024 by AM BV2014 and 322,063 by MPM LLC.

SEC source: 0001209191-19-010312 · doc4.xml · nonDerivative · entry 3

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 3,843,830

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F3 · ownership.nature: Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F5 · ownership.nature: The shares are held as follows: 3,192,985 by BV 2014, 212,964 by BV 2014(B), 115,818 by AM BV2014 and 322,063 by MPM LLC.

SEC source: 0001209191-19-010312 · doc4.xml · nonDerivative · entry 2

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 3,425,978

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F3 · ownership.nature: Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

F4 · ownership.nature: The shares are held as follows: 2,814,142 by BV 2014, 187,696 by BV 2014(B), 102,077 by AM BV2014 and 322,063 by MPM LLC.

SEC source: 0001209191-19-010312 · doc4.xml · nonDerivative · entry 1

MPM BioVentures 2014, L.P. · CIK 0001609492 · 10% owner

MPM ASSET MANAGEMENT LLC · CIK 0001263048 · 10% owner

MPM BioVentures 2014 (B), L.P. · CIK 0001609493 · 10% owner

MPM Asset Management Investors BV2014 LLC · CIK 0001609495 · 10% owner

MPM BioVentures 2014 LLC · CIK 0001765021 · 10% owner

MPM BioVentures 2014 GP LLC · CIK 0001765091 · 10% owner

Foley Todd · CIK 0001473930 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 1,847,227

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date.

F2 · ownership.nature: The shares are held as follows: 1,382,777 by MPM BioVentures 2014, L.P. ("BV 2014"), 92,229 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 50,158 by MPM Asset Management Investors BV2014 LLC ("AM BV2014") and 322,063 by MPM Asset Management LLC ("AM LLC"). MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the members of BV LLC and Luke Evnin and Anbert Gadicke are the members of AM LLC.

F3 · ownership.nature: Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.