STTK

SEC source: 0001193125-26-011860 · ownership.xml · derivative · entry 2

Stout Stephen · CIK 0001970664 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 351,400

Underlying: Common Stock · 351,400 shares

Expires 2036-01-10

F1 · derivative.exercise_date: This option represents a right to purchase a total of 351,400 shares of the Issuer's common stock, one quarter of which will vest on January 10, 2027, with the remaining three quarters vesting in equal monthly installments through January 10, 2030, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0001193125-26-011860 · ownership.xml · nonDerivative · entry 1

Stout Stephen · CIK 0001970664 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 82,122

SEC source: 0001193125-26-011837 · ownership.xml · derivative · entry 2

Pandite Arundathy N. · CIK 0001827232 · Chief Medical Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 487,800

Underlying: Common Stock · 487,800 shares

Expires 2036-01-10

F1 · derivative.exercise_date: This option represents a right to purchase a total of 487,800 shares of the Issuer's common stock, one quarter of which will vest on January 10, 2027, with the remaining three quarters vesting in equal monthly installments through January 10, 2030, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0001193125-26-011837 · ownership.xml · nonDerivative · entry 1

Pandite Arundathy N. · CIK 0001827232 · Chief Medical Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 199,414

SEC source: 0001193125-26-011823 · ownership.xml · derivative · entry 1

Schreiber Taylor · CIK 0001601942 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,548,300

Underlying: Common Stock · 1,548,300 shares

Expires 2036-01-10

F1 · derivative.exercise_date: This option represents the right to purchase a total of 1,548,300 shares of the Issuer's common stock, one quarter of which will vest on January 10, 2027, with the remaining three quarters vesting in equal monthly installments through January 10, 2030, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0001193125-26-011853 · ownership.xml · derivative · entry 2

DeYoung Casi · CIK 0001652066 · Chief Business Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 381,600

Underlying: Common Stock · 381,600 shares

Expires 2036-01-10

F1 · derivative.exercise_date: This option represents a right to purchase a total of 381,600 shares of the Issuer's common stock, one quarter of which will vest on January 10, 2027, with the remaining three quarters vesting in equal monthly installments through January 10, 2030, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0001193125-26-011853 · ownership.xml · nonDerivative · entry 1

DeYoung Casi · CIK 0001652066 · Chief Business Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 75,766

SEC source: 0001193125-26-011828 · ownership.xml · derivative · entry 2

Neill Andrew R · CIK 0001827204 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 549,800

Underlying: Common Stock · 549,800 shares

Expires 2036-01-10

F1 · derivative.exercise_date: This option represents a right to purchase a total of 549,800 shares of the Issuer's common stock, one quarter of which will vest on January 10, 2027, with the remaining three quarters vesting in equal monthly installments through January 10, 2030, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0001193125-26-011828 · ownership.xml · nonDerivative · entry 1

Neill Andrew R · CIK 0001827204 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 230,813

SEC source: 0001193125-26-011847 · ownership.xml · derivative · entry 1

Shukla Abhinav A. · CIK 0001923377 · Chief Technical Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 315,500

Underlying: Common Stock · 315,500 shares

Expires 2036-01-10

F1 · derivative.exercise_date: This option represents a right to purchase a total of 315,500 shares of the Issuer's common stock, one quarter of which will vest on January 10, 2027, with the remaining three quarters vesting in equal monthly installments through January 10, 2030, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0001193125-25-193327 · ownership.xml · derivative · entry 1

Baker Daniel G. · CIK 0002046802 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 66,300

Underlying: Common Stock · 66,300 shares

Expires 2035-08-28

F1 · derivative.exercise_date: This option represents the right to purchase a total of 66,300 shares of the Issuer's common stock, and vests in three equal annual installments on each of the first three anniversaries of August 28, 2025, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0001193125-25-193328 · ownership.xml · derivative · entry 1

Ashiya Mona · CIK 0001794070 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 66,300

Underlying: Common Stock · 66,300 shares

Expires 2035-08-28

F1 · derivative.exercise_date: This option represents the right to purchase a total of 66,300 shares of the Issuer's common stock, and vests in three equal annual installments on each of the first three anniversaries of August 28, 2025, subject to the Reporting Person's continued service to the Issuer.

F2 · ownership.direct: Pursuant to an agreement with OrbiMed Advisors LLC and OrbiMed Capital GP IX LLC, the Reporting Person is obligated to transfer any securities issued under any such stock options or other awards, or the economic benefit thereof, to OrbiMed Advisors LLC and OrbiMed Capital GP IX LLC, which will in turn ensure that such securities or economic benefits are provided to OrbiMed Private Investments IX, LP.

SEC source: 0001104659-25-083134 · tm2524352-2_4seq1.xml · derivative · entry 2

Redmile Group, LLC · CIK 0001425738 · Director · 10% owner

Green Jeremy · CIK 0001650527 · 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: 4,097,730

Underlying: Common Stock · 4,097,730 shares

Expires not disclosed

F1 · price: On August 25, 2025 (the "Closing Date"), pursuant to the terms of that certain securities purchase agreement, dated as of August 4, 2025 (the "Purchase Agreement") and following the satisfaction of certain material conditions set forth therein, the Issuer issued and sold to certain institutional investors in a private placement, including certain private investment vehicles managed by Redmile Group, LLC (the "Redmile Clients"), pre-funded warrants (the "Pre-Funded Warrants") to purchase shares of the Issuer's common stock, par value $0.0001 per share (the "Common Stock"), accompanied by warrants (the "Common Warrants") to purchase an equal number of shares of Common Stock (or, in lieu thereof, Pre-Funded Warrants to purchase up to the same number of shares), at a combined purchase price for both securities of $0.8676.

F2 · derivative.exercise_date: The Pre-Funded Warrants and Common Warrants are exercisable by the holder at any time on or after the Closing Date, subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants do not have an expiration date. The Common Warrants will expire 30 days after a public announcement of the data from the Issuer's Phase 1 clinical trial for SL-325 in healthy volunteers and the design of its Phase 2 clinical trial.

F2 · derivative.expiration_date: The Pre-Funded Warrants and Common Warrants are exercisable by the holder at any time on or after the Closing Date, subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants do not have an expiration date. The Common Warrants will expire 30 days after a public announcement of the data from the Issuer's Phase 1 clinical trial for SL-325 in healthy volunteers and the design of its Phase 2 clinical trial.

F3 · ownership.nature: The reported securities are directly owned by the Redmile Clients, and may be deemed beneficially owned by Redmile Group, LLC ("Redmile") as the investment manager of the Redmile Clients.

F4 · ownership.nature: The reported securities may also be deemed beneficially owned by Jeremy Green as the principal of Redmile. Redmile and Mr. Green disclaim beneficial ownership of the reported securities except to the extent of its or his pecuniary interest therein, if any, and this Form 4 shall not be deemed an admission that Redmile or Mr. Green is the beneficial owner of the reported securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

SEC source: 0001104659-25-083134 · tm2524352-2_4seq1.xml · derivative · entry 1

Redmile Group, LLC · CIK 0001425738 · Director · 10% owner

Green Jeremy · CIK 0001650527 · 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: 7,198,553

Underlying: Common Stock · 4,097,730 shares

Expires not disclosed

F1 · price: On August 25, 2025 (the "Closing Date"), pursuant to the terms of that certain securities purchase agreement, dated as of August 4, 2025 (the "Purchase Agreement") and following the satisfaction of certain material conditions set forth therein, the Issuer issued and sold to certain institutional investors in a private placement, including certain private investment vehicles managed by Redmile Group, LLC (the "Redmile Clients"), pre-funded warrants (the "Pre-Funded Warrants") to purchase shares of the Issuer's common stock, par value $0.0001 per share (the "Common Stock"), accompanied by warrants (the "Common Warrants") to purchase an equal number of shares of Common Stock (or, in lieu thereof, Pre-Funded Warrants to purchase up to the same number of shares), at a combined purchase price for both securities of $0.8676.

F2 · derivative.exercise_date: The Pre-Funded Warrants and Common Warrants are exercisable by the holder at any time on or after the Closing Date, subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants do not have an expiration date. The Common Warrants will expire 30 days after a public announcement of the data from the Issuer's Phase 1 clinical trial for SL-325 in healthy volunteers and the design of its Phase 2 clinical trial.

F2 · derivative.expiration_date: The Pre-Funded Warrants and Common Warrants are exercisable by the holder at any time on or after the Closing Date, subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants do not have an expiration date. The Common Warrants will expire 30 days after a public announcement of the data from the Issuer's Phase 1 clinical trial for SL-325 in healthy volunteers and the design of its Phase 2 clinical trial.

F3 · ownership.nature: The reported securities are directly owned by the Redmile Clients, and may be deemed beneficially owned by Redmile Group, LLC ("Redmile") as the investment manager of the Redmile Clients.

F4 · ownership.nature: The reported securities may also be deemed beneficially owned by Jeremy Green as the principal of Redmile. Redmile and Mr. Green disclaim beneficial ownership of the reported securities except to the extent of its or his pecuniary interest therein, if any, and this Form 4 shall not be deemed an admission that Redmile or Mr. Green is the beneficial owner of the reported securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

SEC source: 0001193125-25-189085 · ownership.xml · derivative · entry 2

SIEGALL CLAY B · CIK 0001167496 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 128,054

Underlying: Common Stock · 128,054 shares

Expires not disclosed

F1 · kind: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 128,054 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 128,054 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 128,054 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 128,054 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F2 · derivative.exercise_date: The Warrants are exercisable at any time on or after the original issuance date until the 30th day following the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Warrants are exercisable at any time on or after the original issuance date until the 30th day following the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

SEC source: 0001193125-25-189085 · ownership.xml · nonDerivative · entry 1

SIEGALL CLAY B · CIK 0001167496 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 128,054

F1 · kind: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 128,054 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 128,054 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 128,054 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 128,054 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

SEC source: 0001193125-25-189086 · ownership.xml · derivative · entry 2

Stout Stephen · CIK 0001970664 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 12,805

Underlying: Common Stock · 12,805 shares

Expires not disclosed

F1 · kind: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 12,805 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 12,805 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 12,805 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 12,805 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F2 · derivative.exercise_date: The Warrants are exercisable at any time on or after the original issuance date until the 30th day following the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Warrants are exercisable at any time on or after the original issuance date until the 30th day following the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

SEC source: 0001193125-25-189086 · ownership.xml · nonDerivative · entry 1

Stout Stephen · CIK 0001970664 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 86,275

F1 · kind: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 12,805 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 12,805 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 12,805 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 12,805 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

SEC source: 0001193125-25-189087 · ownership.xml · derivative · entry 3

Schreiber Taylor · CIK 0001601942 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,610

Underlying: Common Stock · 25,610 shares

Expires not disclosed

F1 · kind: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 25,610 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 25,610 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 25,610 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 25,610 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F2 · derivative.exercise_date: The Warrants are exercisable at any time on or after the original issuance date until the 30th day following the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Warrants are exercisable at any time on or after the original issuance date until the 30th day following the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

SEC source: 0001193125-25-189087 · ownership.xml · nonDerivative · entry 1

Schreiber Taylor · CIK 0001601942 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 96,612

F1 · kind: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 25,610 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 25,610 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 25,610 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 25,610 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

SEC source: 0001193125-25-189088 · ownership.xml · derivative · entry 2

Neill Andrew R · CIK 0001827204 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 64,027

Underlying: Common Stock · 64,027 shares

Expires not disclosed

F1 · kind: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 64,027 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 64,027 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 64,027 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 64,027 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F2 · derivative.exercise_date: The Warrants are exercisable at any time on or after the original issuance date until the 30th day following the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Warrants are exercisable at any time on or after the original issuance date until the 30th day following the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

SEC source: 0001193125-25-189088 · ownership.xml · nonDerivative · entry 1

Neill Andrew R · CIK 0001827204 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 237,473

F1 · kind: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 64,027 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 64,027 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 64,027 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 64,027 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

SEC source: 0001193125-25-189084 · ownership.xml · derivative · entry 2

Shukla Abhinav A. · CIK 0001923377 · Chief Technical Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 5,122

Underlying: Common Stock · 5,122 shares

Expires not disclosed

F1 · kind: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 5,122 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 5,122 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 5,122 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 5,122 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F3 · derivative.exercise_date: The Warrants are exercisable at any time on or after the original issuance date until the 30th day following the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F3 · derivative.expiration_date: The Warrants are exercisable at any time on or after the original issuance date until the 30th day following the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

SEC source: 0001193125-25-189084 · ownership.xml · nonDerivative · entry 1

Shukla Abhinav A. · CIK 0001923377 · Chief Technical Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 81,258

F1 · kind: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 5,122 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 5,122 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Person. Pursuant to the terms of the Purchase Agreement, the Issuer in a private placement, which closed on August 25, 2025, issued and sold to the Reporting Person 5,122 shares of the Issuer's common stock and accompanying warrants (the "Warrants") to purchase up to an aggregate of 5,122 shares of the Issuer's common stock at a combined price per share and accompanying Warrant of $0.8677.

F2 · balance_after: Includes 600 shares acquired by the Reporting Person under the Issuer's 2020 Employee Stock Purchase Plan (the "ESPP") on February 15, 2025 and 2,000 shares acquired by the Reporting Person under the ESPP on August 15, 2025.

SEC source: 0000947871-25-000840 · ownership.xml · derivative · entry 6

ORBIMED ADVISORS LLC · CIK 0001055951 · Director

OrbiMed Capital GP IX LLC · CIK 0001920574 · Director

OrbiMed Genesis GP LLC · CIK 0001808744 · Director

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 3,073,298

Underlying: Common Stock · 3,073,298 shares

Expires not disclosed

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Persons. Pursuant to the terms of the Purchase Agreement, the Issuer issued and sold to the Reporting Persons in a private placement which closed on August 25, 2025 (the "Closing Date") an aggregate of 6,306,127 shares of the Issuer's common stock ("Shares") and pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 12,133,661 Shares. The Reporting Persons also received accompanying common warrants ("Common Warrants") to purchase up to an aggregate of 18,439,799 Shares. The price per Share and accompanying Common Warrant is $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant is $0.8676.

F2 · derivative.exercise_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F4 · ownership.nature: These securities are held of record by OrbiMed Genesis Master Fund, L.P. ("Genesis Master Fund"). OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis Master Fund. OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by Genesis Master Fund. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by Genesis Master Fund.

F5 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, GP IX, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors has designated a representative, Mona Ashiya ("Ashiya"), a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any of the Reporting Persons or Ashiya is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000840 · ownership.xml · derivative · entry 5

ORBIMED ADVISORS LLC · CIK 0001055951 · Director

OrbiMed Capital GP IX LLC · CIK 0001920574 · Director

OrbiMed Genesis GP LLC · CIK 0001808744 · Director

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 15,366,490

Underlying: Common Stock · 15,366,490 shares

Expires not disclosed

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Persons. Pursuant to the terms of the Purchase Agreement, the Issuer issued and sold to the Reporting Persons in a private placement which closed on August 25, 2025 (the "Closing Date") an aggregate of 6,306,127 shares of the Issuer's common stock ("Shares") and pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 12,133,661 Shares. The Reporting Persons also received accompanying common warrants ("Common Warrants") to purchase up to an aggregate of 18,439,799 Shares. The price per Share and accompanying Common Warrant is $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant is $0.8676.

F2 · derivative.exercise_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments IX, LP ("OPI IX"). OrbiMed Capital GP IX LLC ("GP IX") is the general partner of OPI IX. OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisers Act of 1940, as amended, is the managing member of GP IX. By virtue of such relationships, GP IX and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by OPI XI. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI IX.

F5 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, GP IX, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors has designated a representative, Mona Ashiya ("Ashiya"), a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any of the Reporting Persons or Ashiya is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000840 · ownership.xml · derivative · entry 4

ORBIMED ADVISORS LLC · CIK 0001055951 · Director

OrbiMed Capital GP IX LLC · CIK 0001920574 · Director

OrbiMed Genesis GP LLC · CIK 0001808744 · Director

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 2,022,277

Underlying: Common Stock · 2,022,277 shares

Expires not disclosed

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Persons. Pursuant to the terms of the Purchase Agreement, the Issuer issued and sold to the Reporting Persons in a private placement which closed on August 25, 2025 (the "Closing Date") an aggregate of 6,306,127 shares of the Issuer's common stock ("Shares") and pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 12,133,661 Shares. The Reporting Persons also received accompanying common warrants ("Common Warrants") to purchase up to an aggregate of 18,439,799 Shares. The price per Share and accompanying Common Warrant is $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant is $0.8676.

F2 · derivative.exercise_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F4 · ownership.nature: These securities are held of record by OrbiMed Genesis Master Fund, L.P. ("Genesis Master Fund"). OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis Master Fund. OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by Genesis Master Fund. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by Genesis Master Fund.

F5 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, GP IX, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors has designated a representative, Mona Ashiya ("Ashiya"), a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any of the Reporting Persons or Ashiya is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000840 · ownership.xml · derivative · entry 3

ORBIMED ADVISORS LLC · CIK 0001055951 · Director

OrbiMed Capital GP IX LLC · CIK 0001920574 · Director

OrbiMed Genesis GP LLC · CIK 0001808744 · Director

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 10,111,384

Underlying: Common Stock · 10,111,384 shares

Expires not disclosed

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors, including the Reporting Persons. Pursuant to the terms of the Purchase Agreement, the Issuer issued and sold to the Reporting Persons in a private placement which closed on August 25, 2025 (the "Closing Date") an aggregate of 6,306,127 shares of the Issuer's common stock ("Shares") and pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 12,133,661 Shares. The Reporting Persons also received accompanying common warrants ("Common Warrants") to purchase up to an aggregate of 18,439,799 Shares. The price per Share and accompanying Common Warrant is $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant is $0.8676.

F2 · derivative.exercise_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments IX, LP ("OPI IX"). OrbiMed Capital GP IX LLC ("GP IX") is the general partner of OPI IX. OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisers Act of 1940, as amended, is the managing member of GP IX. By virtue of such relationships, GP IX and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by OPI XI. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI IX.

F5 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, GP IX, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors has designated a representative, Mona Ashiya ("Ashiya"), a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any of the Reporting Persons or Ashiya is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000840 · ownership.xml · nonDerivative · entry 2

ORBIMED ADVISORS LLC · CIK 0001055951 · Director

OrbiMed Capital GP IX LLC · CIK 0001920574 · Director

OrbiMed Genesis GP LLC · CIK 0001808744 · Director

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 1,051,021

F4 · ownership.nature: These securities are held of record by OrbiMed Genesis Master Fund, L.P. ("Genesis Master Fund"). OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis Master Fund. OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by Genesis Master Fund. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by Genesis Master Fund.

F5 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, GP IX, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors has designated a representative, Mona Ashiya ("Ashiya"), a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any of the Reporting Persons or Ashiya is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000840 · ownership.xml · nonDerivative · entry 1

ORBIMED ADVISORS LLC · CIK 0001055951 · Director

OrbiMed Capital GP IX LLC · CIK 0001920574 · Director

OrbiMed Genesis GP LLC · CIK 0001808744 · Director

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 5,255,106

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments IX, LP ("OPI IX"). OrbiMed Capital GP IX LLC ("GP IX") is the general partner of OPI IX. OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisers Act of 1940, as amended, is the managing member of GP IX. By virtue of such relationships, GP IX and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by OPI XI. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI IX.

F5 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, GP IX, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors has designated a representative, Mona Ashiya ("Ashiya"), a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any of the Reporting Persons or Ashiya is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000839 · ownership.xml · derivative · entry 6

Ashiya Mona · CIK 0001794070 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 3,073,298

Underlying: Common Stock · 3,073,298 shares

Expires not disclosed

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors. Pursuant to the terms of the Purchase Agreement, the Issuer issued and sold to the OrbiMed Private Investments IX, LP ("OPI IX") and OrbiMed Genesis Master Fund, L.P. ("Genesis Master Fund") in a private placement which closed on August 25, 2025 (the "Closing Date") an aggregate of 6,306,127 shares of the Issuer's common stock ("Shares") and pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 12,133,661 Shares. OPI IX and Genesis Master Fund also received accompanying common warrants ("Common Warrants") to purchase up to an aggregate of 18,439,799 Shares. The price per Share and accompanying Common Warrant is $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant is $0.8676.

F2 · derivative.exercise_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F4 · ownership.nature: These securities are held of record by Genesis Master Fund. OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis Master Fund. OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by Genesis Master Fund. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by Genesis Master Fund.

F5 · ownership.nature: Each of the Reporting Person, OrbiMed Advisors, GP IX, and Genesis GP disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, GP IX, or Genesis GP is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000839 · ownership.xml · derivative · entry 5

Ashiya Mona · CIK 0001794070 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 15,366,490

Underlying: Common Stock · 15,366,490 shares

Expires not disclosed

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors. Pursuant to the terms of the Purchase Agreement, the Issuer issued and sold to the OrbiMed Private Investments IX, LP ("OPI IX") and OrbiMed Genesis Master Fund, L.P. ("Genesis Master Fund") in a private placement which closed on August 25, 2025 (the "Closing Date") an aggregate of 6,306,127 shares of the Issuer's common stock ("Shares") and pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 12,133,661 Shares. OPI IX and Genesis Master Fund also received accompanying common warrants ("Common Warrants") to purchase up to an aggregate of 18,439,799 Shares. The price per Share and accompanying Common Warrant is $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant is $0.8676.

F2 · derivative.exercise_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F3 · ownership.nature: These securities are held of record by OPI IX. OrbiMed Capital GP IX LLC ("GP IX") is the general partner of OPI IX. OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisers Act of 1940, as amended, is the managing member of GP IX. By virtue of such relationships, GP IX and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by OPI XI. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI IX.

F5 · ownership.nature: Each of the Reporting Person, OrbiMed Advisors, GP IX, and Genesis GP disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, GP IX, or Genesis GP is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000839 · ownership.xml · derivative · entry 4

Ashiya Mona · CIK 0001794070 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 2,022,277

Underlying: Common Stock · 2,022,277 shares

Expires not disclosed

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors. Pursuant to the terms of the Purchase Agreement, the Issuer issued and sold to the OrbiMed Private Investments IX, LP ("OPI IX") and OrbiMed Genesis Master Fund, L.P. ("Genesis Master Fund") in a private placement which closed on August 25, 2025 (the "Closing Date") an aggregate of 6,306,127 shares of the Issuer's common stock ("Shares") and pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 12,133,661 Shares. OPI IX and Genesis Master Fund also received accompanying common warrants ("Common Warrants") to purchase up to an aggregate of 18,439,799 Shares. The price per Share and accompanying Common Warrant is $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant is $0.8676.

F2 · derivative.exercise_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F4 · ownership.nature: These securities are held of record by Genesis Master Fund. OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis Master Fund. OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by Genesis Master Fund. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by Genesis Master Fund.

F5 · ownership.nature: Each of the Reporting Person, OrbiMed Advisors, GP IX, and Genesis GP disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, GP IX, or Genesis GP is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000839 · ownership.xml · derivative · entry 3

Ashiya Mona · CIK 0001794070 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 10,111,384

Underlying: Common Stock · 10,111,384 shares

Expires not disclosed

F1 · price: On August 4, 2025, the Issuer entered into a securities purchase agreement (the "Purchase Agreement") with certain accredited investors. Pursuant to the terms of the Purchase Agreement, the Issuer issued and sold to the OrbiMed Private Investments IX, LP ("OPI IX") and OrbiMed Genesis Master Fund, L.P. ("Genesis Master Fund") in a private placement which closed on August 25, 2025 (the "Closing Date") an aggregate of 6,306,127 shares of the Issuer's common stock ("Shares") and pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 12,133,661 Shares. OPI IX and Genesis Master Fund also received accompanying common warrants ("Common Warrants") to purchase up to an aggregate of 18,439,799 Shares. The price per Share and accompanying Common Warrant is $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant is $0.8676.

F2 · derivative.exercise_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F2 · derivative.expiration_date: The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants are exercisable at any time after the Closing Date, in each case subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full. The Common Warrants will expire on the 30th day after the date on which the data from the single ascending dose and multiple ascending dose portions of the Issuer's Phase 1 clinical trial of SL-325, including receptor occupancy and safety data, and the design of the planned Phase 2 clinical trial(s) have been announced publicly.

F3 · ownership.nature: These securities are held of record by OPI IX. OrbiMed Capital GP IX LLC ("GP IX") is the general partner of OPI IX. OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisers Act of 1940, as amended, is the managing member of GP IX. By virtue of such relationships, GP IX and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by OPI XI. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI IX.

F5 · ownership.nature: Each of the Reporting Person, OrbiMed Advisors, GP IX, and Genesis GP disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, GP IX, or Genesis GP is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000839 · ownership.xml · nonDerivative · entry 2

Ashiya Mona · CIK 0001794070 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 1,051,021

F4 · ownership.nature: These securities are held of record by Genesis Master Fund. OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis Master Fund. OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by Genesis Master Fund. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by Genesis Master Fund.

F5 · ownership.nature: Each of the Reporting Person, OrbiMed Advisors, GP IX, and Genesis GP disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, GP IX, or Genesis GP is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-25-000839 · ownership.xml · nonDerivative · entry 1

Ashiya Mona · CIK 0001794070 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 5,255,106

F3 · ownership.nature: These securities are held of record by OPI IX. OrbiMed Capital GP IX LLC ("GP IX") is the general partner of OPI IX. OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisers Act of 1940, as amended, is the managing member of GP IX. By virtue of such relationships, GP IX and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by OPI XI. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI IX.

F5 · ownership.nature: Each of the Reporting Person, OrbiMed Advisors, GP IX, and Genesis GP disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1943, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, GP IX, or Genesis GP is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000950170-25-096284 · ownership.xml · derivative · entry 1

SIEGALL CLAY B · CIK 0001167496 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,150

Underlying: Common Stock · 33,150 shares

Expires 2035-07-14

F1 · derivative.exercise_date: This option represents the right to purchase a total of 33,150 shares of the Issuer's common stock, which will vest in full on the earlier of the one-year anniversary of the grant date or immediately prior to the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0000950170-25-096280 · ownership.xml · derivative · entry 1

Sasser Amy Kate · CIK 0002013454 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,150

Underlying: Common Stock · 33,150 shares

Expires 2035-07-14

F1 · derivative.exercise_date: This option represents the right to purchase a total of 33,150 shares of the Issuer's common stock, which will vest in full on the earlier of the one-year anniversary of the grant date or immediately prior to the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0000950170-25-096266 · ownership.xml · derivative · entry 1

Brownstein Carrie · CIK 0001894232 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,150

Underlying: Common Stock · 33,150 shares

Expires 2035-07-14

F1 · derivative.exercise_date: This option represents the right to purchase a total of 33,150 shares of the Issuer's common stock, which will vest in full on the earlier of the one-year anniversary of the grant date or immediately prior to the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0000950170-25-096242 · ownership.xml · derivative · entry 1

Boudreau Helen M · CIK 0001661481 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,150

Underlying: Common Stock · 33,150 shares

Expires 2035-07-14

F1 · derivative.exercise_date: This option represents the right to purchase a total of 33,150 shares of the Issuer's common stock, which will vest in full on the earlier of the one-year anniversary of the grant date or immediately prior to the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0001104659-25-068453 · tm2521022-1_4seq1.xml · derivative · entry 1

Redmile Group, LLC · CIK 0001425738 · Director · 10% owner

Green Jeremy · CIK 0001650527 · 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: 33,150

Underlying: Common Stock · 33,150 shares

Expires 2035-07-14

F1 · derivative.exercise_date: This option represents a right to purchase a total of 33,150 shares of the Issuer's common stock, which will vest in full on the earlier of (i) the one-year anniversary of the grant date or (ii) immediately prior to the next annual meeting of the Issuer's shareholders, subject to Mr. Michael Lee's continued service to the Issuer through such date.

F2 · ownership.nature: The stock option was granted to Mr. Lee, a managing director of Redmile Group, LLC ("Redmile"), in connection with his service as a member of the Board of Directors of the Issuer. Pursuant to the policies of Redmile, Mr. Lee holds this stock option as a nominee on behalf, and for the sole benefit, of Redmile and has assigned all economic, pecuniary and voting rights in respect of the stock option to Redmile. Mr. Lee disclaims beneficial ownership of the stock option, and the filing of this Form 4 shall not be deemed an admission that Mr. Lee is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

F3 · ownership.nature: The stock option may also be deemed beneficially owned by Jeremy Green as the principal of Redmile. Redmile and Mr. Green disclaim beneficial ownership of the stock option except to the extent of their pecuniary interest therein, if any, and this Form 4 shall not be deemed an admission that Redmile or Mr. Green is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

SEC source: 0000950170-25-096273 · ownership.xml · derivative · entry 1

Gibson Neil W · CIK 0001555918 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,150

Underlying: Common Stock · 33,150 shares

Expires 2035-07-14

F1 · derivative.exercise_date: This option represents the right to purchase a total of 33,150 shares of the Issuer's common stock, which will vest in full on the earlier of the one-year anniversary of the grant date or immediately prior to the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0000950170-25-096275 · ownership.xml · derivative · entry 1

Golumbeski George · CIK 0001586660 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,150

Underlying: Common Stock · 33,150 shares

Expires 2035-07-14

F1 · derivative.exercise_date: This option represents the right to purchase a total of 33,150 shares of the Issuer's common stock, which will vest in full on the earlier of the one-year anniversary of the grant date or immediately prior to the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0001104659-25-068454 · tm2521022-2_4seq1.xml · derivative · entry 1

Lee Michael Stewart · CIK 0001748010 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,150

Underlying: Common Stock · 33,150 shares

Expires 2035-07-14

F1 · derivative.exercise_date: This option represents a right to purchase a total of 33,150 shares of the Issuer's common stock, which will vest in full on the earlier of (i) the one-year anniversary of the grant date or (ii) immediately prior to the next annual meeting of the Issuer's shareholders, subject to the Reporting Person's continued service to the Issuer through such date.

F2 · ownership.direct: The stock option was granted to Mr. Lee, a managing director of Redmile Group, LLC ("Redmile"), in connection with his service as a member of the Board of Directors of the Issuer. Pursuant to the policies of Redmile, Mr. Lee holds this stock option as a nominee on behalf, and for the sole benefit, of Redmile and has assigned all economic, pecuniary and voting rights in respect of the stock option to Redmile. Mr. Lee disclaims beneficial ownership of the stock option, and the filing of this Form 4 shall not be deemed an admission that Mr. Lee is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

F3 · ownership.direct: The stock option may also be deemed beneficially owned by Jeremy Green as the principal of Redmile. Redmile and Mr. Green disclaim beneficial ownership of the stock option except to the extent of their pecuniary interest therein, if any, and this Form 4 shall not be deemed an admission that Redmile or Mr. Green is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

SEC source: 0000950170-25-096254 · ownership.xml · derivative · entry 1

Brous Tyler · CIK 0001827387 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,150

Underlying: Common Stock · 33,150 shares

Expires 2035-07-14

F1 · derivative.exercise_date: This option represents the right to purchase a total of 33,150 shares of the Issuer's common stock, which will vest in full on the earlier of the one-year anniversary of the grant date or immediately prior to the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0000950170-25-010001 · ownership.xml · derivative · entry 1

Stout Stephen · CIK 0001970664 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 177,000

Underlying: Common Stock · 177,000 shares

Expires 2035-01-28

F1 · derivative.exercise_date: This option represents a right to purchase a total of 177,000 shares of the Issuer's common stock, one quarter of which will vest on January 28, 2026, with the remaining three quarters vesting in equal monthly installments through January 28, 2029, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0000950170-25-010004 · ownership.xml · derivative · entry 2

Pandite Arundathy N. · CIK 0001827232 · Chief Medical Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 206,200

Underlying: Common Stock · 206,200 shares

Expires 2035-01-28

F1 · derivative.exercise_date: This option represents a right to purchase a total of 206,200 shares of the Issuer's common stock, one quarter of which will vest on January 28, 2026, with the remaining three quarters vesting in equal monthly installments through January 28, 2029, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0000950170-25-009987 · ownership.xml · derivative · entry 1

Schreiber Taylor · CIK 0001601942 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 684,600

Underlying: Common Stock · 684,600 shares

Expires 2035-01-28

F1 · derivative.exercise_date: This option represents the right to purchase a total of 684,600 shares of the Issuer's common stock, one quarter of which will vest on January 28, 2026, with the remaining three quarters vesting in equal monthly installments through January 28, 2029, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0000950170-25-010009 · ownership.xml · derivative · entry 2

DeYoung Casi · CIK 0001652066 · Chief Business Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 194,300

Underlying: Common Stock · 194,300 shares

Expires 2035-01-28

F1 · derivative.exercise_date: This option represents a right to purchase a total of 194,300 shares of the Issuer's common stock, one quarter of which will vest on January 28, 2026, with the remaining three quarters vesting in equal monthly installments through January 28, 2029, subject to the Reporting Person's continued service to the Issuer.

SEC source: 0000950170-25-010013 · ownership.xml · derivative · entry 2

Shukla Abhinav A. · CIK 0001923377 · Chief Technical Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 165,200

Underlying: Common Stock · 165,200 shares

Expires 2035-01-28

F2 · derivative.exercise_date: This option represents a right to purchase a total of 165,200 shares of the Issuer's common stock, one quarter of which will vest on January 28, 2026, with the remaining three quarters vesting in equal monthly installments through January 28, 2029, subject to the Reporting Person's continued service to the Issuer.