Sec Form 3 Filing - Luptakova Katarina @ Xilio Therapeutics, Inc. - 2023-09-05

FORM 3 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 Luptakova Katarina 2. Issuer Name and Ticker or Trading Symbol Xilio Therapeutics, Inc. [ XLO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Medical Officer (Last) (First) (Middle) 828 WINTER STREET, SUITE 300 3. Date of Earliest Transaction (MM/DD/YY) 09/05/2023 (Street) WALTHAM, MA02451 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

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 Stock Option (right to buy) $ 9.69 ( 1 ) 12/06/2031 Common Stock 44,210 D Stock Option (right to buy) $ 2.37 ( 2 ) 10/31/2032 Common Stock 15,000 D Stock Option (right to buy) $ 2.69 ( 3 ) 12/31/2032 Common Stock 35,000 D Stock Option (right to buy) $ 2.785 ( 4 ) 08/15/2033 Common Stock 25,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Luptakova Katarina 828 WINTER STREET, SUITE 300 WALTHAM, MA02451 Chief Medical Officer Signatures /s/ Julia Walcott, Attorney-in-Fact 09/07/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The option was granted on December 7, 2021 for 44,210 shares. On December 2, 2022, 25% of the shares underlying the option vested and the remainder continues to vest in equal monthly installments thereafter through December 2, 2025. ( 2 )The option was granted on November 1, 2022 for 15,000 shares. The shares underlying the option began vesting on December 1, 2022 and shall vest in equal monthly installments thereafter through November 1, 2026. ( 3 )The option was granted on January 1, 2023 for 35,000 shares. The shares underlying the option began vesting on February 1, 2023 and shall vest in equal monthly installments thereafter through January 1, 2027. ( 4 )The option was granted on August 16, 2023 for 25,0000 shares and shall vest with respect to 1/3 of the shares underlying the option on August 16, 2024 and with respect to the remaining 2/3 of the shares underlying the option on August 16, 2025.

Remarks: Exhibit Index: 24.1 Power of Attorney

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).

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