Table of Contents ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ________ to ________. Commission file number: 001-40925 XILIO THERAPEUTICS, INC. (Exact name of registrant as specified in its charter) (State of Other Jurisdiction of incorporation or Organization) (I.R.S. Employer Identification No.) 828 Winter Street, Suite 300, Waltham, MA 02451 (Address of principal executive offices) (Zip code) Delaware 85-1623397 UNITED STATES SE ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2021 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40925 Xilio Therapeutics, Inc. (Exact name of registrant as specified in its charter) Delaware 85-1623397 ...