STTK · Shattuck Labs, Inc.

This option represents a right to purchase a total of 52,200 shares of the Issuer's common stock, one quarter of which will vest on January 25, 2024, with the remaining three quarters vesting in equal monthly installments through January 25, 2027, subject to the Reporting Person's continued service to the Issuer.

Sale of shares effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on February 2, 2026. The plan is intended to execute sales of shares received upon option exercise only as needed to fund the exercise price and estimated tax withholding associated with option exercises under the plan. Under the procedures of the administering broker, acquired shares are first sold to fund the aggregate exercise price and estimated tax withholding with respect to all possible option exercises in a particular order under the plan and only once fully funded will acquired shares be held by the Reporting Person. This transaction represents the final sale of shares needed to fully fund the exercise price and estimated tax withholding for the option exercises under this order of the plan and the remaining shares acquired upon exercise under this order will be held by the Reporting Person.

The price reported above is a weighted average price. The shares were sold in multiple transactions at prices ranging from $7.000 to $7.030, 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.

This option represents a right to purchase a total of 52,200 shares of the Issuer's common stock, one quarter of which will vest on January 25, 2024, with the remaining three quarters vesting in equal monthly installments through January 25, 2027, subject to the Reporting Person's continued service to the Issuer.

This option represents a right to purchase a total of 52,200 shares of the Issuer's common stock, one quarter of which will vest on January 25, 2024, with the remaining three quarters vesting in equal monthly installments through January 25, 2027, subject to the Reporting Person's continued service to the Issuer.

Sale of shares effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on February 2, 2026. The plan is intended to execute sales of shares received upon option exercise only as needed to fund the exercise price and estimated tax withholding associated with option exercises under the plan. Under the procedures of the administering broker, acquired shares are first sold to fund the aggregate exercise price and estimated tax withholding with respect to all possible option exercises in a particular order under the plan and only once fully funded will acquired shares be held by the Reporting Person.

Sale of shares effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on February 2, 2026. The plan is intended to execute sales of shares received upon option exercise only as needed to fund the exercise price and estimated tax withholding associated with option exercises under the plan. Under the procedures of the administering broker, acquired shares are first sold to fund the aggregate exercise price and estimated tax withholding with respect to all possible option exercises in a particular order under the plan and only once fully funded will acquired shares be held by the Reporting Person.

The price reported above is a weighted average price. The shares were sold in multiple transactions at prices ranging from $7.00 to $7.41, 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.

Sale of shares effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on February 2, 2026.

The price reported above is a weighted average price. The shares were sold in multiple transactions at prices ranging from $6.62 to $7.40, 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.

This option represents a right to purchase a total of 52,200 shares of the Issuer's common stock, one quarter of which will vest on January 25, 2024, with the remaining three quarters vesting in equal monthly installments through January 25, 2027, subject to the Reporting Person's continued service to the Issuer.

On June 9, 2026, the Issuer announced a public offering of an aggregate of 10,879,376 shares of common stock ("Shares") at a price of $4.00 per Share and, in lieu of Shares to certain investors, pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 7,870,624 Shares at a price of $3.9999 per Pre-Funded Warrant. The Pre-Funded Warrant have an exercise price of $0.0001 per share and are exercisable at any time after the date of issuance. The public offering closed on June 11, 2026.

The Pre-Funded Warrants are exercisable at any time after the date of issuance, subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full.

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.

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.

On June 9, 2026, the Issuer announced a public offering of an aggregate of 10,879,376 shares of common stock ("Shares") at a price of $4.00 per Share and, in lieu of Shares to certain investors, pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 7,870,624 Shares at a price of $3.9999 per Pre-Funded Warrant. The Pre-Funded Warrant have an exercise price of $0.0001 per share and are exercisable at any time after the date of issuance. The public offering closed on June 11, 2026.

The Pre-Funded Warrants are exercisable at any time after the date of issuance, subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full.

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.

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.

On June 9, 2026, the Issuer announced a public offering of an aggregate of 10,879,376 shares of common stock ("Shares") at a price of $4.00 per Share and, in lieu of Shares to certain investors, pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 7,870,624 Shares at a price of $3.9999 per Pre-Funded Warrant. The Pre-Funded Warrant have an exercise price of $0.0001 per share and are exercisable at any time after the date of issuance. The public offering closed on June 11, 2026.

The Pre-Funded Warrants are exercisable at any time after the date of issuance, subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full.

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.

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.

On June 9, 2026, the Issuer announced a public offering of an aggregate of 10,879,376 shares of common stock ("Shares") at a price of $4.00 per Share and, in lieu of Shares to certain investors, pre-funded warrants ("Pre-Funded Warrants") to purchase up to an aggregate of 7,870,624 Shares at a price of $3.9999 per Pre-Funded Warrant. The Pre-Funded Warrant have an exercise price of $0.0001 per share and are exercisable at any time after the date of issuance. The public offering closed on June 11, 2026.

The Pre-Funded Warrants are exercisable at any time after the date of issuance, subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants will expire once exercised in full.

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.

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.

Represents shares of the Issuer's common stock purchased in connection with the Issuer's underwritten offering, which closed on June 11, 2026.

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 or, if so elected by Reporting Persons, Pre-Funded Warrants. The price per Share and accompanying Common Warrant was $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant was $0.8676. On June 8, 2026, the Reporting Persons exercised their Common Warrants in exchange for an equal amount of Pre-Funded Warrants.

The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants were 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 would have expired 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.

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.

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.

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 or, if so elected by Reporting Persons, Pre-Funded Warrants. The price per Share and accompanying Common Warrant was $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant was $0.8676. On June 8, 2026, the Reporting Persons exercised their Common Warrants in exchange for an equal amount of Pre-Funded Warrants.

The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants were 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 would have expired 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.

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.

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.

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 or, if elected, Pre-Funded Warrants. The price per Share and accompanying Common Warrant were $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant were $0.8676. On June 8, 2026, the Common Warrants were exercised in exchange for Pre-Funded Warrants.

The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants were 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 would have expired 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.

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.

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.

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 or, if so elected by Reporting Persons, Pre-Funded Warrants. The price per Share and accompanying Common Warrant was $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant was $0.8676. On June 8, 2026, the Reporting Persons exercised their Common Warrants in exchange for an equal amount of Pre-Funded Warrants.

The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants were 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 would have expired 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.

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.

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.

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 or, if so elected by Reporting Persons, Pre-Funded Warrants. The price per Share and accompanying Common Warrant was $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant was $0.8676. On June 8, 2026, the Reporting Persons exercised their Common Warrants in exchange for an equal amount of Pre-Funded Warrants.

The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants were 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 would have expired 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.

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.

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.

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 or, if elected, Pre-Funded Warrants. The price per Share and accompanying Common Warrant were $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant were $0.8676. On June 8, 2026, the Common Warrants were exercised in exchange for Pre-Funded Warrants.

The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants were 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 would have expired 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.

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.

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.

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 or, if elected, Pre-Funded Warrants. The price per Share and accompanying Common Warrant were $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant were $0.8676. On June 8, 2026, the Common Warrants were exercised in exchange for Pre-Funded Warrants.

The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants were 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 would have expired 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.

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.

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.

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 or, if elected, Pre-Funded Warrants. The price per Share and accompanying Common Warrant were $0.8677. The price per Pre-Funded Warrant and accompanying Common Warrant were $0.8676. On June 8, 2026, the Common Warrants were exercised in exchange for Pre-Funded Warrants.

The Pre-Funded Warrants are exercisable at any time after the date of issuance and the Common Warrants were 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 would have expired 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.

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.

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.

This option represents the right to purchase a total of 81,000 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.

This option represents the right to purchase a total of 81,000 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.

This option represents the right to purchase a total of 81,000 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.

This option represents the right to purchase a total of 81,000 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.

This option represents the right to purchase a total of 81,000 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.

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.

This option represents the right to purchase a total of 81,000 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.

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.

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.

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.

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.

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.

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.

Sale of shares effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on February 2, 2026. The plan is intended to execute sales of shares received upon option exercise only as needed to fund the exercise price and estimated tax withholding associated with option exercises under the plan. Under the procedures of the administering broker, acquired shares are first sold to fund the aggregate exercise price and estimated tax withholding with respect to all possible option exercises in a particular order under the plan and only once fully funded will acquired shares be held by the Reporting Person.

The price reported above is a weighted average price. The shares were sold in multiple transactions at prices ranging from $7.00 to $7.02, 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.

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.

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.

Sale of shares effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on February 2, 2026.

The price reported above is a weighted average price. The shares were sold in multiple transactions at prices ranging from $6.41 to $7.03, 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

This option represents a right to purchase a total of 52,200 shares of the Issuer's common stock, one quarter of which will vest on January 25, 2024, with the remaining three quarters vesting in equal monthly installments through January 25, 2027, subject to the Reporting Person's continued service to the Issuer.

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.

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.