SEC Form 3

FORM 3

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

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1. Name and Address of Reporting Person* Rock Springs Capital Management LP (Last) (First) (Middle) 650 SOUTH EXETER ST., SUITE 1070 (Street) BALTIMORE MD 21202 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 10/21/2021	3. Issuer Name and Ticker or Trading Symbol Xilio Therapeutics, Inc. [ XLO ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series C Preferred Stock	(1)	(1)	Common Stock	756,472	(1)	I	See footnote(2)
Series C Preferred Stock	(1)	(1)	Common Stock	151,294	(1)	I	See footnote(3)

1. Name and Address of Reporting Person* Rock Springs Capital Management LP (Last) (First) (Middle) 650 SOUTH EXETER ST., SUITE 1070 (Street) BALTIMORE MD 21202 (City) (State) (Zip)

1. Name and Address of Reporting Person* Rock Springs Capital LLC (Last) (First) (Middle) 650 SOUTH EXETER ST., SUITE 1070 (Street) BALTIMORE MD 21202 (City) (State) (Zip)

1. Name and Address of Reporting Person* Rock Springs Capital Master Fund LP (Last) (First) (Middle) 190 ELGIN AVENUE (Street) GEORGE TOWN E9 KY1 9001 (City) (State) (Zip)

1. Name and Address of Reporting Person* Four Pines Master Fund LP (Last) (First) (Middle) 650 SOUTH EXETER ST., SUITE 1070 (Street) BALTIMORE MD 21202 (City) (State) (Zip)

Explanation of Responses:

1. The Series C Preferred Stock automatically converts into the number of shares of Common Stock as shown in Column 3 without payment of further consideration at the holder's election or upon closing of the initial public offering of the Issuer's common stock. The shares have no expiration date.

2. The securities reported herein are held of record by Rock Springs Capital Master Fund LP ("Master Fund"). Rock Springs Capital LLC ("RSC") is the general partner of Rock Springs Capital Management LP ("RSCM") which is the investment manager to Master Fund. RSC and RSCM may therefore be deemed to have or share beneficial ownership of the Series C Preferred Stock held directly by Master Fund.

3. The securities reported herein are held of record by Four Pines Master Fund LP ("Four Pines"). RSC is the general partner of RSCM which is the investment manager to Four Pines. RSC and RSCM may therefore be deemed to have or share beneficial ownership of the Series C Preferred Stock held directly by Four Pines.

	By: /s/ Mark Bussard, Authorized Signatory, Rock Springs Capital Management LP	10/21/2021
	By: /s/ Mark Bussard, Authorized Signatory, Rock Springs Capital LLC	10/21/2021
	By: /s/ Mark Bussard, Authorized Signatory, Rock Springs Capital Master Fund LP	10/21/2021
	By: /s/ Mark Bussard, Authorized Signatory, Four Pines Master Fund LP	10/21/2021
	** Signature of Reporting Person	Date
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 5 (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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