Joint Filer Information

Name:	Deerfield Mgmt V, L.P., Deerfield Mgmt, L.P., Deerfield Management Company, L.P., Deerfield Private Design Fund V, L.P., and Deerfield Partners, L.P.
Address:	345 Park Avenue South, 12th Floor New York, NY 10010
Designated Filer:	James E. Flynn
Issuer and Ticker Symbol:	Xilio Therapeutics, Inc. [XLO]
Date of Event Requiring Statement:	October 21, 2021

The undersigned, Deerfield Mgmt V, L.P., Deerfield Mgmt, L.P., Deerfield Management Company, L.P., Deerfield Private Design Fund V, L.P., and Deerfield Partners, L.P. are jointly filing the attached Initial Statement of Beneficial Ownership on Form 3 with James E. Flynn with respect to the beneficial ownership of securities of Xilio Therapeutics, Inc.

Signatures:

DEERFIELD MGMT, L.P. By: J.E. Flynn Capital, LLC, General Partner By: /s/ Jonathan Isler Jonathan Isler, Attorney-In-Fact	DEERFIELD MGMT V, L.P. By: J.E. Flynn Capital V, LLC, General Partner By: /s/ Jonathan Isler Jonathan Isler, Attorney-In-Fact
DEERFIELD PARTNERS, L.P. By: Deerfield Mgmt, L.P., General Partner By: J.E. Flynn Capital, LLC, General Partner By: /s/ Jonathan Isler Jonathan Isler, Attorney-In-Fact	DEERFIELD PRIVATE DESIGN FUND V, L.P. By: Deerfield Mgmt V, L.P., General Partner By: J.E. Flynn Capital V, LLC, General Partner By: /s/ Jonathan Isler Jonathan Isler, Attorney-In-Fact
DEERFIELD MANAGEMENT COMPANY, L.P. By: Flynn Management LLC, General Partner By: /s/ Jonathan Isler Jonathan Isler, Attorney-In-Fact