Amendment: SEC Form SCHEDULE 13D/A filed by Shattuck Labs Inc.

Item 2(b) of the Prior Schedule 13D is hereby amended and restated in its entirety as follows: Redmile: 900 Larkspur Landing Circle, Suite 270 Larkspur, California 94939 Jeremy C. Green: c/o Redmile Group, LLC (NY Office) 45 W. 27th Street, Floor 11 New York, NY 10001 RBI II: c/o Redmile Group, LLC 900 Larkspur Landing Circle, Suite 270 Larkspur, California 94939

Item 3 of the Prior Schedule 13D is hereby amended and supplemented in its entirety by adding the following paragraphs after the last paragraph of Item 3: On June 3, 2026, certain private investment funds managed by Redmile (the "Redmile Funds"), not including RBI II, exercised on a cashless basis certain pre-funded warrants to purchase Common Stock (the "Pre-Funded Warrants") in accordance with the terms thereof, at an exercise price of $0.0001 per share. The participating Redmile Funds were issued an aggregate of 1,012,203 shares of Common Stock by the Issuer, net of the warrant shares representing the aggregate exercise price. On June 9, 2026, certain Redmile Funds, including RBI II, exercised all of the Common Warrants held by such Redmile Funds in accordance with the terms thereof, which were exercisable, at the holder's sole discretion, for either Common Stock, at an exercise price of $1.0846 per share, or Pre-Funded Warrants, at an exercise price of $1.0845 per Pre-Funded Warrant. The participating Redmile Funds, including RBI II, elected to receive 340,106 shares of Common Stock and Pre-Funded Warrants to purchase an aggregate of 3,757,624 shares of Common Stock and utilized their working capital to pay the aggregate exercise price of approximately $4,444,022. Of the securities acquired by the participating Redmile Funds upon exercise of the Common Warrants, RBI II utilized its working capital to pay an aggregate exercise price of approximately $2,221,514 to receive Pre-Funded Warrants to purchase 2,048,423 shares of Common Stock. On June 9, 2026, certain Redmile Funds, not including RBI II, also participated in an underwritten offering of the Issuer's Common Stock and Pre-Funded Warrants (the "Underwritten Offering") and utilized their working capital in an aggregate amount of approximately $3,999,900 to acquire Pre-Funded Warrants to purchase 1,000,000 shares of Common Stock at a price of $3.9999 per Pre-Funded Warrant, each with an exercise price of $0.0001 per share.

Item 5(a) of the Prior Schedule 13D is hereby amended and restated in its entirety as follows: The aggregate amount of shares of Common Stock that may be deemed beneficially owned by the Reporting Persons is comprised of (i) 7,038,119 shares of Common Stock held by the Redmile Funds, including the 3,338,997 shares of Common Stock directly held by RBI II, and (ii) subject to the 9.99% beneficial ownership limitation (the "Beneficial Ownership Limitation"), 10,943,951 shares of Common Stock issuable upon exercise of the Pre-Funded Warrants, including the 5,647,258 shares of Common Stock issuable upon exercise of the Pre-Funded Warrants directly held by RBI II. The 2,780,965 shares of Common Stock issuable upon exercise of the Pre-Funded Warrants reported as beneficially owned by the Reporting Persons represent the maximum number of shares of Common Stock that could be issued upon exercise of those Pre-Funded Warrants subject to the Beneficial Ownership Limitation. All of the reported securities are directly owned by certain Redmile Funds. Redmile may be deemed to beneficially own these securities in its capacity as the investment manager of the Redmile Funds with discretion to vote and dispose of their portfolio securities. Mr. Green also may be deemed to beneficially own these securities as the principal of Redmile. Redmile and Mr. Green each disclaim beneficial ownership of the reported securities, except to the extent of its or his pecuniary interest in such securities, if any. Redmile and Mr. Green may be deemed to beneficially own 146,086 shares of Common Stock subject to options to purchase shares of Common Stock that are exercisable within 60 days of the date of this filing, and such amount is included in the number disclosed in (i) above. The stock options were granted to Mike Lee, a managing director of Redmile, in connection with his former service as a member of the Board of Directors, which ceased on August 25, 2025. Pursuant to the policies of Redmile, Mr. Lee holds the stock options 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 options to Redmile. Percentage for each Reporting Person based on sum of: (i) 95,508,165 shares of Common Stock outstanding immediately after the Underwritten Offering (including the exercise of the underwriters' option to purchase additional shares of Common Stock), as reported by the Issuer in its Prospectus Supplement to the Prospectus dated January 21, 2026, which was filed with the Securities and Exchange Commission on June 11, 2026, plus (ii) 2,780,965 shares of Common Stock issuable upon exercise of certain Pre-Funded Warrants directly held by the Redmile Funds (including RBI II), which due to the Beneficial Ownership Limitation is the maximum number of shares that could be issued upon exercise of those Warrants.

Item 5(b) of the Prior Schedule 13D is hereby amended and restated in its entirety as follows: Redmile: (1) Sole Voting Power: 0 (2) Shared Voting Power: 9,819,084 (3) Sole Dispositive Power: 0 (4) Shared Dispositive Power: 9,819,084 Jeremy C. Green: (1) Sole Voting Power: 0 (2) Shared Voting Power: 9,819,084 (3) Sole Dispositive Power: 0 (4) Shared Dispositive Power: 9,819,084 RBI II: (1) Sole Voting Power: 0 (2) Shared Voting Power: 6,119,962 (3) Sole Dispositive Power: 0 (4) Shared Dispositive Power: 6,119,962

See the response to Item 3. Except as disclosed in Item 3, no reportable transactions were effected by any Reporting Persons during the past sixty days.

Item 6 of the Prior Schedule 13D is hereby amended and supplemented in its entirety by adding the following paragraphs prior to the last paragraph of Item 6: Pre-Funded Warrants to Purchase Common Stock Pre-Funded Warrants were acquired by the Redmile Funds, not including RBI II, in the Underwritten Offering at a price of $3.9999 per Pre-Funded Warrant and entitle the holder to purchase up to an aggregate of 1,000,000 shares of Common Stock, subject to the Beneficial Ownership Blocker, at an exercise price of $0.0001 per Pre-Funded Warrant. The Pre-Funded Warrants are exercisable by the holder at any time on or after the issuance date until fully exercised. The foregoing summary of the Pre-Funded Warrants is not intended to be complete and is qualified in its entirety by reference to the full text of the Form of Pre-Funded Warrant, which is filed as Exhibit 99.12 to this Schedule 13D and is incorporated herein by reference.

Exhibit 99.12 Form of Pre-Funded Warrant (incorporated by reference to Exhibit 4.1 to the Issuer's Current Report on Form 8-K filed on June 11, 2026).