CLYM

SEC source: 0001231919-26-001416 · form4-09302026_080936.xml · derivative · entry 13

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Common Stock · 40,000 shares

Expires 2026-09-29

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.

F8 · derivative.exercise_date: Immediately exercisable.

F1 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F2 · ownership.nature: This option was granted to Andrew Levin pursuant to the Issuer's non-employee director compensation policy. Under Dr. Levin's arrangement with the Adviser, Dr. Levin held the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account. Dr. Levin is obligated to turn over to the Adviser any stock received upon exercise of the option, which will offset advisory fees owed by the Fund to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001231919-26-001416 · form4-09302026_080936.xml · derivative · entry 12

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Common Stock · 10,000 shares

Expires 2026-09-29

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.

F8 · derivative.exercise_date: Immediately exercisable.

F1 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F2 · ownership.nature: This option was granted to Andrew Levin pursuant to the Issuer's non-employee director compensation policy. Under Dr. Levin's arrangement with the Adviser, Dr. Levin held the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account. Dr. Levin is obligated to turn over to the Adviser any stock received upon exercise of the option, which will offset advisory fees owed by the Fund to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001231919-26-001416 · form4-09302026_080936.xml · derivative · entry 11

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Common Stock · 10,000 shares

Expires 2026-09-29

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.

F8 · derivative.exercise_date: Immediately exercisable.

F1 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F2 · ownership.nature: This option was granted to Andrew Levin pursuant to the Issuer's non-employee director compensation policy. Under Dr. Levin's arrangement with the Adviser, Dr. Levin held the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account. Dr. Levin is obligated to turn over to the Adviser any stock received upon exercise of the option, which will offset advisory fees owed by the Fund to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001231919-26-001416 · form4-09302026_080936.xml · derivative · entry 10

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 0

Underlying: Common Stock · 10,000 shares

Expires 2026-09-29

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.

F8 · derivative.exercise_date: Immediately exercisable.

F1 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F2 · ownership.nature: This option was granted to Andrew Levin pursuant to the Issuer's non-employee director compensation policy. Under Dr. Levin's arrangement with the Adviser, Dr. Levin held the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account. Dr. Levin is obligated to turn over to the Adviser any stock received upon exercise of the option, which will offset advisory fees owed by the Fund to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001231919-26-001416 · form4-09302026_080936.xml · nonDerivative · entry 4

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 70,000

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 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F2 · ownership.nature: This option was granted to Andrew Levin pursuant to the Issuer's non-employee director compensation policy. Under Dr. Levin's arrangement with the Adviser, Dr. Levin held the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account. Dr. Levin is obligated to turn over to the Adviser any stock received upon exercise of the option, which will offset advisory fees owed by the Fund to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001231919-26-001416 · form4-09302026_080936.xml · nonDerivative · entry 3

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 30,000

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 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F2 · ownership.nature: This option was granted to Andrew Levin pursuant to the Issuer's non-employee director compensation policy. Under Dr. Levin's arrangement with the Adviser, Dr. Levin held the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account. Dr. Levin is obligated to turn over to the Adviser any stock received upon exercise of the option, which will offset advisory fees owed by the Fund to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001231919-26-001416 · form4-09302026_080936.xml · nonDerivative · entry 2

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 20,000

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 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F2 · ownership.nature: This option was granted to Andrew Levin pursuant to the Issuer's non-employee director compensation policy. Under Dr. Levin's arrangement with the Adviser, Dr. Levin held the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account. Dr. Levin is obligated to turn over to the Adviser any stock received upon exercise of the option, which will offset advisory fees owed by the Fund to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001231919-26-001416 · form4-09302026_080936.xml · nonDerivative · entry 1

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 10,000

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 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F2 · ownership.nature: This option was granted to Andrew Levin pursuant to the Issuer's non-employee director compensation policy. Under Dr. Levin's arrangement with the Adviser, Dr. Levin held the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account. Dr. Levin is obligated to turn over to the Adviser any stock received upon exercise of the option, which will offset advisory fees owed by the Fund to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001193125-26-394357 · ownership.xml · nonDerivative · entry 1

Thomas Stephen Basil · CIK 0002027962 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 467,969

F1 · kind: These transactions were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on June 16, 2026.

F2 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $13.3800 to $14.3400, inclusive. The reporting person undertakes to provide the staff of the Securities and Exchange Commission, the issuer or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · balance_after: Includes 413,312 shares of the issuer's common stock, par value $0.0001 per share, distributed by Sera Medicines, LLC to certain of its limited partners, including the reporting person, for no consideration in a pro-rata in-kind distribution.

SEC source: 0001193125-26-291131 · ownership.xml · nonDerivative · entry 2

Brennan Aoife · CIK 0001714563 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 87,731

F3 · kind: The sale reported on this Form 4 was made pursuant to a 10b5-1 trading plan adopted by the Reporting Person on August 30, 2024 to cover tax withholding obligations in connection with the vesting and settlement of the Reporting Person's RSUs.

F4 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices within the range of $13.02 to $13.34, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this Form 4.

SEC source: 0001231919-26-000722 · form4-07012026_090743.xml · derivative · entry 1

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnotes

Disclosed balance after: 70,284

Underlying: Common Stock · 70,284 shares

Expires 2036-06-29

F1 · derivative.exercise_date: The shares underlying the option vest in equal monthly installments from June 29, 2026 (the "Vesting Commencement Date") until the third anniversary of the Vesting Commencement Date, subject to Ms. Celebi's continued service through such date.

F2 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F3 · ownership.nature: Under Ms. Celebi's arrangement with the Adviser, Ms. Celebi holds the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account. Ms. Celebi is obligated to turn over to the Adviser any net cash or stock received upon exercise of the option, which will offset advisory fees owed by the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001193125-26-292640 · ownership.xml · derivative · entry 1

Celebi Breanna Maurine · CIK 0002137903 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 70,284

Underlying: Common Stock · 70,284 shares

Expires 2036-06-29

F1 · derivative.exercise_date: The shares underlying the option vest in equal monthly installments from June 29, 2026 (the "Vesting Commencement Date") until the third anniversary of the Vesting Commencement Date, subject to the Reporting Person's continued service through such date.

F2 · ownership.direct: Under the Reporting Person's arrangement with RA Capital Management, L.P. (the "Adviser"), the Reporting Person holds the stock option for the benefit of the RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The Reporting Person is obligated to turn over to the Adviser any net cash or stock received upon exercise of the stock option, which will offset advisory fees owed by the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account to the Adviser. The Reporting Person therefore disclaims beneficial ownership of the stock option and underlying common stock.

SEC source: 0001193125-26-291131 · ownership.xml · derivative · entry 3

Brennan Aoife · CIK 0001714563 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 137,500

Underlying: Common Stock · 68,750 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.

F5 · derivative.exercise_price: Each RSU represents a contingent right to receive one share of the Issuer's Common Stock.

F6 · derivative.exercise_date: The RSUs were granted on June 27, 2024 (the "Grant Date") and are scheduled to vest over four years, with 25% of the shares vesting on each of the first four anniversaries of the Grant Date, subject to the Reporting Person's continued service.

F6 · derivative.expiration_date: The RSUs were granted on June 27, 2024 (the "Grant Date") and are scheduled to vest over four years, with 25% of the shares vesting on each of the first four anniversaries of the Grant Date, subject to the Reporting Person's continued service.

SEC source: 0001193125-26-291131 · ownership.xml · nonDerivative · entry 1

Brennan Aoife · CIK 0001714563 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 118,633

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: Each restricted stock unit ("RSU") converted into one share of the Issuer's Common Stock

F2 · balance_after: Total includes an additional 1,751 shares acquired through the Company's Employee Stock Purchase Plan.

SEC source: 0001193125-26-262270 · ownership.xml · derivative · entry 1

Dunn Judith · CIK 0001811904 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2036-06-04

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 5, 2027 or the date immediately prior to the date of the next annual meeting of stockholders, subject to the reporting person's continued service through such date.

SEC source: 0001193125-26-262273 · ownership.xml · derivative · entry 1

Thomas Stephen Basil · CIK 0002027962 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2036-06-04

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 5, 2027 or the date immediately prior to the date of the next annual meeting of stockholders, subject to the reporting person's continued service through such date.

SEC source: 0001193125-26-262281 · ownership.xml · derivative · entry 1

Cumbo Alexander · CIK 0001685994 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2036-06-04

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 5, 2027 or the date immediately prior to the date of the next annual meeting of stockholders, subject to the reporting person's continued service through such date.

SEC source: 0001193125-26-262287 · ownership.xml · derivative · entry 1

WILLIAMS DOUGLAS E · CIK 0001184847 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2036-06-04

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 5, 2027 or the date immediately prior to the date of the next annual meeting of stockholders, subject to the reporting person's continued service through such date.

SEC source: 0001231919-26-000610 · form4-06082026_100640.xml · derivative · entry 1

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnotes

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2036-06-04

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 5, 2027 or the day immediately prior to the next annual meeting of stockholders, subject to Dr. Andrew Levin's continuous service through such date.

F2 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F3 · ownership.nature: Under Dr. Levin's arrangement with the Adviser, Dr. Levin holds the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account. Dr. Levin is obligated to turn over to the Adviser any net cash or stock received upon exercise of the option, which will offset advisory fees owed by the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001193125-26-262290 · ownership.xml · derivative · entry 1

Drapkin Kimberlee C · CIK 0001340881 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2036-06-04

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 5, 2027 or the date immediately prior to the date of the next annual meeting of stockholders, subject to the reporting person's continued service through such date.

SEC source: 0001193125-26-262292 · ownership.xml · derivative · entry 1

Levin Andrew David · CIK 0001867539 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2036-06-04

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 5, 2027 or the date immediately prior to the date of the next annual meeting of stockholders, subject to the reporting person's continued service through such date.

F2 · ownership.direct: Under the reporting person's arrangement with RA Capital Management, L.P. (the "Adviser"), the reporting person holds the stock option for the benefit of the RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"), RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The reporting person is obligated to turn over to the Adviser any net cash or stock received upon exercise of the stock option, which will offset advisory fees owed by the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, and the Account to the Adviser. The reporting person therefore disclaims beneficial ownership of the stock option and underlying common stock.

SEC source: 0001231919-26-000429 · form4-04292026_100401.xml · derivative · entry 1

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director · 10% owner

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 22,546,000

Underlying: Common Stock · 2,106,000 shares

Expires not disclosed

F1 · derivative.exercise_date: The Pre-Funded Warrants have no expiration date and are exercisable immediately. Notwithstanding the foregoing, the Reporting Persons shall not be entitled to exercise the Pre-Funded Warrant if it would cause the aggregate number of shares of Common Stock beneficially owned by the Reporting Persons, their affiliates and any persons who are members of a Section 13(d) group with the Reporting Persons or their affiliates to exceed 33.0% of the total number of issued and outstanding shares of Common Stock of the Issuer following such exercise.

F1 · derivative.expiration_date: The Pre-Funded Warrants have no expiration date and are exercisable immediately. Notwithstanding the foregoing, the Reporting Persons shall not be entitled to exercise the Pre-Funded Warrant if it would cause the aggregate number of shares of Common Stock beneficially owned by the Reporting Persons, their affiliates and any persons who are members of a Section 13(d) group with the Reporting Persons or their affiliates to exceed 33.0% of the total number of issued and outstanding shares of Common Stock of the Issuer following such exercise.

F2 · ownership.nature: These securities are held directly by RA Capital Healthcare Fund, L.P. (the "Fund").

F3 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus II Fund, L.P. (the "Nexus Fund II"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III") and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Fund and the Nexus Fund III collectively own approximately 75% of the outstanding equity interests of Sera Medicines, LLC ("Sera"). Accordingly, each of the Fund, the Nexus Fund III and the Adviser may be deemed to beneficially own the securities held by Sera. The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the reported securities, except to the extent of their respective pecuniary interest therein.

SEC source: 0001193125-26-082533 · ownership.xml · nonDerivative · entry 2

Thomas Stephen Basil · CIK 0002027962 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 154,657

F1 · kind: These transactions were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on October 14, 2025.

F3 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.0000 to $7.0400, inclusive.

SEC source: 0001193125-26-082533 · ownership.xml · nonDerivative · entry 1

Thomas Stephen Basil · CIK 0002027962 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 170,970

F1 · kind: These transactions were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on October 14, 2025.

F2 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.0000 to $7.0600, inclusive. The reporting person undertakes to provide the staff of the Securities and Exchange Commission, the issuer or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (2) and (3) of this Form 4.

SEC source: 0001193125-26-054568 · ownership.xml · nonDerivative · entry 2

Thomas Stephen Basil · CIK 0002027962 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 204,657

F1 · kind: These transactions were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on October 14, 2025.

F3 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.6200 to $6.1200, inclusive.

SEC source: 0001193125-26-054568 · ownership.xml · nonDerivative · entry 1

Thomas Stephen Basil · CIK 0002027962 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 214,657

F1 · kind: These transactions were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on October 14, 2025.

F2 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.2212 to $5.2481, inclusive. The reporting person undertakes to provide the staff of the Securities and Exchange Commission, the issuer or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (2) and (3) of this Form 4.

SEC source: 0001193125-26-007665 · ownership.xml · derivative · entry 1

ALTSCHULLER Susan · CIK 0001817988 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 142,500

Underlying: Common Stock · 142,500 shares

Expires 2036-01-05

F1 · derivative.exercise_date: This option was granted on January 6, 2026 (the "Grant Date"). The shares underlying the option are scheduled to vest with respect to 25% of the shares on the first anniversary of the Grant Date and the remainder are scheduled to vest in 36 equal monthly installments through January 6, 2030, subject to the Reporting Person's continued service.

SEC source: 0001193125-26-007667 · ownership.xml · derivative · entry 1

Wilson Perrin Megan · CIK 0002074091 · Chief Business Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 300,000

Underlying: Common Stock · 300,000 shares

Expires 2036-01-05

F1 · derivative.exercise_date: This option was granted on January 6, 2026 (the "Grant Date"). The shares underlying the option are scheduled to vest with respect to 25% of the shares on the first anniversary of the Grant Date and the remainder are scheduled to vest in 36 equal monthly installments through January 6, 2030, subject to the Reporting Person's continued service.

SEC source: 0001193125-26-007670 · ownership.xml · derivative · entry 1

Brennan Aoife · CIK 0001714563 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 700,000

Underlying: Common Stock · 700,000 shares

Expires 2036-01-05

F1 · derivative.exercise_date: This option was granted on January 6, 2026 (the "Grant Date"). The shares underlying the option are scheduled to vest with respect to 25% of the shares on the first anniversary of the Grant Date and the remainder are scheduled to vest in 36 equal monthly installments through January 6, 2030, subject to the Reporting Person's continued service.

SEC source: 0001193125-26-007662 · ownership.xml · derivative · entry 1

Driscoll Cindy · CIK 0001741269 · Senior Vice President, Finance

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 100,000

Underlying: Common Stock · 100,000 shares

Expires 2036-01-05

F1 · derivative.exercise_date: This option was granted on January 6, 2026 (the "Grant Date"). The shares underlying the option are scheduled to vest with respect to 25% of the shares on the first anniversary of the Grant Date and the remainder are scheduled to vest in 36 equal monthly installments through January 6, 2030, subject to the Reporting Person's continued service.

SEC source: 0001231919-26-000018 · form4-01072026_090137.xml · nonDerivative · entry 1

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director · 10% owner

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 3,403,429

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $3.495 to $3.50 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

F2 · ownership.nature: These securities are held directly by RA Capital Healthcare Fund, L.P. (the "Fund").

F3 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus II Fund, L.P. (the "Nexus Fund II"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III") and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Fund and the Nexus Fund III collectively own approximately 75% of the outstanding equity interests of Sera Medicines, LLC ("Sera"). Accordingly, each of the Fund, the Nexus Fund III and the Adviser may be deemed to beneficially own the securities held by Sera. The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the reported securities, except to the extent of their respective pecuniary interest therein.

SEC source: 0001231919-25-000616 · form4-12162025_121255.xml · nonDerivative · entry 3

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director · 10% owner

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 3,396,318

F5 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $2.32 to $3.00 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

F2 · ownership.nature: These securities are held directly by RA Capital Healthcare Fund, L.P. (the "Fund").

F3 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus II Fund, L.P. (the "Nexus Fund II"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III") and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Fund and the Nexus Fund III collectively own approximately 75% of the outstanding equity interests of Sera Medicines, LLC ("Sera"). Accordingly, each of the Fund, the Nexus Fund III and the Adviser may be deemed to beneficially own the securities held by Sera. The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the reported securities, except to the extent of their respective pecuniary interest therein.

SEC source: 0001231919-25-000616 · form4-12162025_121255.xml · derivative · entry 9

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director · 10% owner

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 20,440,000

Underlying: Common Stock · 20,440,000 shares

Expires not disclosed

F1 · kind: On December 11, 2025, RA Capital Healthcare Fund, L.P. (the "Fund") entered into an Exchange Agreement with the Issuer pursuant to which the Fund exchanged, for no additional consideration, 20,440,000 shares of the Issuer's Common Stock for a pre-funded warrant exercisable for up to 20,440,000 shares of the Issuer's Common Stock at an exercise price of $0.0001 per share.

F1 · price: On December 11, 2025, RA Capital Healthcare Fund, L.P. (the "Fund") entered into an Exchange Agreement with the Issuer pursuant to which the Fund exchanged, for no additional consideration, 20,440,000 shares of the Issuer's Common Stock for a pre-funded warrant exercisable for up to 20,440,000 shares of the Issuer's Common Stock at an exercise price of $0.0001 per share.

F11 · derivative.exercise_date: The Pre-Funded Warrants have no expiration date and are exercisable immediately. Notwithstanding the foregoing, the Reporting Persons shall not be entitled to exercise the Pre-Funded Warrant if it would cause the aggregate number of shares of Common Stock beneficially owned by the Reporting Persons, their affiliates and any persons who are members of a Section 13(d) group with the Reporting Persons or their affiliates to exceed 33.0% of the total number of issued and outstanding shares of Common Stock of the Issuer following such exercise.

F11 · derivative.expiration_date: The Pre-Funded Warrants have no expiration date and are exercisable immediately. Notwithstanding the foregoing, the Reporting Persons shall not be entitled to exercise the Pre-Funded Warrant if it would cause the aggregate number of shares of Common Stock beneficially owned by the Reporting Persons, their affiliates and any persons who are members of a Section 13(d) group with the Reporting Persons or their affiliates to exceed 33.0% of the total number of issued and outstanding shares of Common Stock of the Issuer following such exercise.

F2 · ownership.nature: These securities are held directly by RA Capital Healthcare Fund, L.P. (the "Fund").

F3 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus II Fund, L.P. (the "Nexus Fund II"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III") and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Fund and the Nexus Fund III collectively own approximately 75% of the outstanding equity interests of Sera Medicines, LLC ("Sera"). Accordingly, each of the Fund, the Nexus Fund III and the Adviser may be deemed to beneficially own the securities held by Sera. The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the reported securities, except to the extent of their respective pecuniary interest therein.

SEC source: 0001231919-25-000616 · form4-12162025_121255.xml · nonDerivative · entry 2

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director · 10% owner

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 3,294,856

F4 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $2.11 to $2.20 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

F2 · ownership.nature: These securities are held directly by RA Capital Healthcare Fund, L.P. (the "Fund").

F3 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus II Fund, L.P. (the "Nexus Fund II"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III") and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Fund and the Nexus Fund III collectively own approximately 75% of the outstanding equity interests of Sera Medicines, LLC ("Sera"). Accordingly, each of the Fund, the Nexus Fund III and the Adviser may be deemed to beneficially own the securities held by Sera. The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the reported securities, except to the extent of their respective pecuniary interest therein.

SEC source: 0001231919-25-000616 · form4-12162025_121255.xml · nonDerivative · entry 1

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund II, L.P. · CIK 0001825376 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director · 10% owner

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 3,081,757

F1 · kind: On December 11, 2025, RA Capital Healthcare Fund, L.P. (the "Fund") entered into an Exchange Agreement with the Issuer pursuant to which the Fund exchanged, for no additional consideration, 20,440,000 shares of the Issuer's Common Stock for a pre-funded warrant exercisable for up to 20,440,000 shares of the Issuer's Common Stock at an exercise price of $0.0001 per share.

F2 · ownership.nature: These securities are held directly by RA Capital Healthcare Fund, L.P. (the "Fund").

F3 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus II Fund, L.P. (the "Nexus Fund II"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III") and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Fund and the Nexus Fund III collectively own approximately 75% of the outstanding equity interests of Sera Medicines, LLC ("Sera"). Accordingly, each of the Fund, the Nexus Fund III and the Adviser may be deemed to beneficially own the securities held by Sera. The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the reported securities, except to the extent of their respective pecuniary interest therein.

SEC source: 0001193125-25-227099 · ownership.xml · derivative · entry 1

ALTSCHULLER Susan · CIK 0001817988 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 600,000

Underlying: Common Stock · 600,000 shares

Expires 2035-09-30

F1 · derivative.exercise_date: This option was granted on October 1, 2025 (the "Grant Date"). The shares underlying the option are scheduled to vest with respect to 25% of the shares on the first anniversary of the Grant Date, and the remainder are scheduled to vest in 36 equal monthly installments through October 1, 2029, subject to the Reporting Person's continued service.

SEC source: 0000950170-25-106563 · ownership.xml · nonDerivative · entry 1

Thomas Stephen Basil · CIK 0002027962 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 304,657

F1 · shares: On June 27, 2024, the reporting person was granted restricted stock units ("RSUs") to acquire a total of 100,375 shares of common stock that vested based on the achievement of certain performance-based milestones and subject to continuous service. On August 7, 2025, the milestones were deemed to be achieved, resulting in the vesting of the RSUs as to all 100,375 shares.

SEC source: 0000950170-25-092284 · ownership.xml · nonDerivative · entry 2

Brennan Aoife · CIK 0001714563 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 48,132

F2 · kind: The sale reported on this Form 4 was made pursuant to a 10b5-1 trading plan adopted by the Reporting Person on August 30, 2024 to cover tax withholding obligations in connection with the vesting and settlement of the Reporting Person's RSUs.

F3 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices within the range of $1.20 to $1.25, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this Form 4.

SEC source: 0000950170-25-092273 · ownership.xml · derivative · entry 2

Thomas Stephen Basil · CIK 0002027962 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 25,094 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: Each RSU represents a contingent right to receive one share of the Issuer's Common Stock.

F3 · derivative.exercise_date: The RSUs were granted on June 27, 2024 and vested as to 50% of the shares on January 1, 2025, vested as to 25% of the shares on March 27, 2025 and vested as to the remaining 25% of the shares on June 27, 2025, subject to the Reporting Person's continued service.

F3 · derivative.expiration_date: The RSUs were granted on June 27, 2024 and vested as to 50% of the shares on January 1, 2025, vested as to 25% of the shares on March 27, 2025 and vested as to the remaining 25% of the shares on June 27, 2025, subject to the Reporting Person's continued service.

SEC source: 0000950170-25-092273 · ownership.xml · nonDerivative · entry 1

Thomas Stephen Basil · CIK 0002027962 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 204,282

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: Each restricted stock unit ("RSU") converted into one share of the Issuer's Common Stock.

SEC source: 0000950170-25-092284 · ownership.xml · derivative · entry 3

Brennan Aoife · CIK 0001714563 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 206,250

Underlying: Common Stock · 68,750 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.

F4 · derivative.exercise_price: Each RSU represents a contingent right to receive one share of the Issuer's Common Stock.

F5 · derivative.exercise_date: The RSUs were granted on June 27, 2024 (the "Grant Date") and are scheduled to vest over four years, with 25% of the shares vesting on each of the first four anniversaries of the Grant Date, subject to the Reporting Person's continued service.

F5 · derivative.expiration_date: The RSUs were granted on June 27, 2024 (the "Grant Date") and are scheduled to vest over four years, with 25% of the shares vesting on each of the first four anniversaries of the Grant Date, subject to the Reporting Person's continued service.

SEC source: 0000950170-25-092284 · ownership.xml · nonDerivative · entry 1

Brennan Aoife · CIK 0001714563 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 68,750

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: Each restricted stock unit ("RSU") converted into one share of the Issuer's Common Stock.

SEC source: 0000950170-25-088524 · ownership.xml · nonDerivative · entry 2

Pimblett Emily · CIK 0001969365 · SVP, Finance & CAO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 18,888

F2 · kind: The sale reported on this Form 4 was made pursuant to a 10b5-1 trading plan adopted by the Reporting Person on April 27, 2024 to cover tax withholding obligations in connection with the vesting and settlement of the Reporting Person's RSUs.

SEC source: 0000950170-25-088524 · ownership.xml · derivative · entry 3

Pimblett Emily · CIK 0001969365 · SVP, Finance & CAO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 15,000

Underlying: Common Stock · 5,000 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.

F3 · derivative.exercise_price: Each RSU represents a contingent right to receive one share of the Issuer's Common Stock.

F4 · derivative.exercise_date: The shares subject to this RSU shall vest at a rate of 1/8th of the total number of shares on the three-month anniversary of March 18, 2024 (the "March 2024 Vesting Commencement Date") and 1/8th of the total number of shares each three-month anniversary of the March 2024 Vesting Commencement Date thereafter for so long as the Reporting Person provides continuous service to the Issuer, such that the total number of shares shall be fully vested on the two-year anniversary of the March 2024 Vesting Commencement Date.

F4 · derivative.expiration_date: The shares subject to this RSU shall vest at a rate of 1/8th of the total number of shares on the three-month anniversary of March 18, 2024 (the "March 2024 Vesting Commencement Date") and 1/8th of the total number of shares each three-month anniversary of the March 2024 Vesting Commencement Date thereafter for so long as the Reporting Person provides continuous service to the Issuer, such that the total number of shares shall be fully vested on the two-year anniversary of the March 2024 Vesting Commencement Date.

SEC source: 0000950170-25-088524 · ownership.xml · nonDerivative · entry 1

Pimblett Emily · CIK 0001969365 · SVP, Finance & CAO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 20,130

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: Each restricted stock unit ("RSU") converted into one share of the Issuer's Common Stock.

SEC source: 0000950170-25-088525 · ownership.xml · derivative · entry 1

Driscoll Cindy · CIK 0001741269 · Senior Vice President, Finance

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 200,000

Underlying: Common Stock · 200,000 shares

Expires 2035-06-16

F1 · derivative.exercise_date: This option was granted on June 17, 2025 (the "Grant Date"). The shares underlying the option are scheduled to vest with respect to 25% of the shares on the first anniversary of the Grant Date and the remainder are scheduled to vest in 36 equal monthly installments through June 17, 2029, subject to the Reporting Person's continued service.

SEC source: 0000950170-25-082323 · ownership.xml · derivative · entry 1

Dunn Judith · CIK 0001811904 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2035-06-03

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 4, 2026 or the date immediately prior to the date of the next annual meeting of stockholders, subject to the reporting person's continued service through such date.

SEC source: 0000950170-25-082320 · ownership.xml · derivative · entry 1

Thomas Stephen Basil · CIK 0002027962 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2035-06-03

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 4, 2026 or the date immediately prior to the date of the next annual meeting of stockholders, subject to the reporting person's continued service through such date.

SEC source: 0000950170-25-082324 · ownership.xml · derivative · entry 1

Cumbo Alexander · CIK 0001685994 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2035-06-03

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 4, 2026 or the date immediately prior to the date of the next annual meeting of stockholders, subject to the reporting person's continued service through such date.

SEC source: 0000950170-25-082322 · ownership.xml · derivative · entry 1

WILLIAMS DOUGLAS E · CIK 0001184847 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 40,000 shares

Expires 2035-06-03

F1 · derivative.exercise_date: The shares subject to the option will vest on the earlier of June 4, 2026 or the date immediately prior to the date of the next annual meeting of stockholders, subject to the reporting person's continued service through such date.