X0609 4 2026-06-11 0001840233 Xilio Therapeutics, Inc. XLO 0001733077 ROSS ROBERT W. false 828 WINTER STREET SUITE 300 WALTHAM MA 02451 true false false false false Stock Option (right to buy) 7.99 2026-06-11 4 A false 5000 0 A 2036-06-10 Common Stock 5000 5000 D The option was granted on June 11, 2026 and will vest as to 100% of the shares underlying the option on the earlier of (i) June 11, 2027 and (ii) the Issuer's next annual meeting of stockholders following the grant date, subject to the Reporting Person's continued service to the Issuer through the vesting date. /s/ Christopher Frankenfield, Attorney-in-Fact 2026-06-12