Sec Form 4 Filing - Gupta Rishi @ Turnstone Biologics Corp. - 2023-07-20

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Gupta Rishi 2. Issuer Name and Ticker or Trading Symbol Turnstone Biologics Corp. [ TSBX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O TURNSTONE BIOLOGICS CORP., 9310 ATHENA CIRCLE, SUITE 300 3. Date of Earliest Transaction (MM/DD/YY) 07/20/2023 (Street) LA JOLLA, CA92037 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 07/20/2023 C 2,682,599 A 2,682,599 I See Footnote ( 2 ) ( 3 ) Common Stock 07/20/2023 P 416,666 A $ 12 3,099,265 I See Footnote ( 2 ) ( 3 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series B-1 Preferred Stock ( 1 ) 07/20/2023 C 937,372 ( 1 ) ( 1 ) Common Stock 937,372 ( 1 ) 0 I See Footnotes ( 2 ) ( 3 ) Series B-2 Preferred Stock ( 1 ) 07/20/2023 C 1,249,829 ( 1 ) ( 1 ) Common Stock 1,249,829 ( 1 ) 0 I See Footnotes ( 2 ) ( 3 ) Series C Preferred Stock ( 1 ) 07/20/2023 C 266,240 ( 1 ) ( 1 ) Common Stock 266,240 ( 1 ) 0 I See Footnotes ( 2 ) ( 3 ) Series D Preferred Stock ( 1 ) 07/20/2023 C 229,158 ( 1 ) ( 1 ) Common Stock 229,158 ( 1 ) 0 I See Footnotes ( 2 ) ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Gupta Rishi C/O TURNSTONE BIOLOGICS CORP. 9310 ATHENA CIRCLE, SUITE 300 LA JOLLA, CA92037 X X Signatures /s/ Rishi Gupta 07/24/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each share of Series B-1 Preferred Stock, Series B-2 Preferred Stock, Series C Preferred Stock, and Series D Preferred Stock automatically converted into shares of the Issuer's common stock on a one-to-one basis immediately prior to the closing of the Issuer's initial public offering and have no expiration date. ( 2 )These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI, and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP VI. The Reporting Person is an employee of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and, as a result, may be deemed to have beneficial ownership over such securities. 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 securities held by OPI VI. ( 3 )Each of the Reporting Person, OrbiMed Advisors and GP VI disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of his or its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Person, GP VI, or OrbiMed Advisors is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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