SCHEDULE 13G 0002068530 XXXXXXXX LIVE Common Stock, par value $0.0001 per share 12/04/2025 0001840233 Xilio Therapeutics, Inc. 98422T100 828 Winter Street Suite 300 Waltham MA 02451 Rule 13d-1(b) Rule 13d-1(c) Coastlands Capital LP b DE 0.00 5346069.00 0.00 5346069.00 5346069.00 N 9.99 IA PN The calculation of the beneficial ownership of the Reporting Persons is based on (i) 52,500,328 shares of Common Stock issued and outstanding as of November 11, 2025, as reported by the Issuer in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 13, 2025, and (ii) 1,013,882 shares of Common Stock issuable upon the exercise of pre-funded warrants held by the Reporting Persons, which reflects the beneficial ownership limitation of 9.99%. Excludes pre-funded warrants held by the Reporting Persons in excess of such beneficial ownership limitation and Common Stock warrants held by the Reporting Persons with a beneficial ownership limitation of 4.99%. Coastlands Capital Partners LP b DE 0.00 5346069.00 0.00 5346069.00 5346069.00 N 9.99 PN The calculation of the beneficial ownership of the Reporting Persons is based on (i) 52,500,328 shares of Common Stock issued and outstanding as of November 11, 2025, as reported by the Issuer in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 13, 2025, and (ii) 1,013,882 shares of Common Stock issuable upon the exercise of pre-funded warrants held by the Reporting Persons, which reflects the beneficial ownership limitation of 9.99%. Excludes pre-funded warrants held by the Reporting Persons in excess of such beneficial ownership limitation and Common Stock warrants held by the Reporting Persons with a beneficial ownership limitation of 4.99%. Coastlands Capital GP LLC b DE 0.00 5346069.00 0.00 5346069.00 5346069.00 N 9.99 OO The calculation of the beneficial ownership of the Reporting Persons is based on (i) 52,500,328 shares of Common Stock issued and outstanding as of November 11, 2025, as reported by the Issuer in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 13, 2025, and (ii) 1,013,882 shares of Common Stock issuable upon the exercise of pre-funded warrants held by the Reporting Persons, which reflects the beneficial ownership limitation of 9.99%. Excludes pre-funded warrants held by the Reporting Persons in excess of such beneficial ownership limitation and Common Stock warrants held by the Reporting Persons with a beneficial ownership limitation of 4.99%. Coastlands Capital LLC b DE 0.00 5346069.00 0.00 5346069.00 5346069.00 N 9.99 HC OO The calculation of the beneficial ownership of the Reporting Persons is based on (i) 52,500,328 shares of Common Stock issued and outstanding as of November 11, 2025, as reported by the Issuer in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 13, 2025, and (ii) 1,013,882 shares of Common Stock issuable upon the exercise of pre-funded warrants held by the Reporting Persons, which reflects the beneficial ownership limitation of 9.99%. Excludes pre-funded warrants held by the Reporting Persons in excess of such beneficial ownership limitation and Common Stock warrants held by the Reporting Persons with a beneficial ownership limitation of 4.99%. Matthew D. Perry b X1 0.00 5346069.00 0.00 5346069.00 5346069.00 N 9.99 HC IN The calculation of the beneficial ownership of the Reporting Persons is based on (i) 52,500,328 shares of Common Stock issued and outstanding as of November 11, 2025, as reported by the Issuer in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 13, 2025, and (ii) 1,013,882 shares of Common Stock issuable upon the exercise of pre-funded warrants held by the Reporting Persons, which reflects the beneficial ownership limitation of 9.99%. Excludes pre-funded warrants held by the Reporting Persons in excess of such beneficial ownership limitation and Common Stock warrants held by the Reporting Persons with a beneficial ownership limitation of 4.99%. Xilio Therapeutics, Inc. 828 Winter Street Suite 300 Waltham, MA, 02451 Coastlands Capital LP, a Delaware limited partnership ("Coastlands") Coastlands Capital Partners LP, a Delaware limited partnership (the "Partnership") Coastlands Capital GP LLC, a Delaware limited liability company (the "General Partner") Coastlands Capital LLC, a Delaware limited liability company ("Coastlands GP") Matthew D. Perry Coastlands and the General Partner are the investment adviser and general partner, respectively, of the Partnership. Coastlands GP is the general partner of Coastlands. Mr. Perry is the control person of Coastlands, the Partnership, Coastlands GP and the General Partner. The reporting persons are filing this Schedule 13G jointly, but not as members of a group, and each disclaims membership in a group. Each reporting person also disclaims beneficial ownership of Common Stock except to the extent of that person's pecuniary interest therein. In addition, the filing of this Schedule 13G on behalf of the Partnership should not be construed as an admission that it is, and it disclaims that it is, a beneficial owner, as defined in Rule 13d-3 under the Act, of any Common Stock covered by this Schedule 13G. 601 California Street, Suite 1210, San Francisco, CA 94108 See Item 4 of the cover sheet for each reporting person. N IA HC Coastlands: 5,346,069 Partnership: 5,346,069 General Partner: 5,346,069 Coastlands GP: 5,346,069 Matthew D. Perry: 5,346,069 Coastlands: 9.99% Partnership: 9.99% General Partner: 9.99% Coastlands GP: 9.99% Matthew D. Perry: 9.99% Coastlands: 0 Partnership: 0 General Partner: 0 Coastlands GP: 0 Matthew D. Perry: 0 Coastlands: 5,346,069 Partnership: 5,346,069 General Partner: 5,346,069 Coastlands GP: 5,346,069 Matthew D. Perry: 5,346,069 Coastlands: 0 Partnership: 0 General Partner: 0 Coastlands GP: 0 Matthew D. Perry: 0 Coastlands: 5,346,069 Partnership: 5,346,069 General Partner: 5,346,069 Coastlands GP: 5,346,069 Matthew D. Perry: 5,346,069 Y N The Partnership holds the shares of Common Stock, including shares of Common Stock issuable upon exercise of pre-funded warrants and Common Stock warrants, for the benefit of its investors and has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, shares of Common Stock, including shares of Common Stock issuable upon exercise of pre-funded warrants and Common Stock warrants. Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. Exhibit 99.1 - Agreement Regarding Joint Filing of Statement on Schedule 13D or 13G Coastlands Capital LP /s/ Mark Shamia 12/11/2025 Coastlands Capital Partners LP /s/ Mark Shamia 12/11/2025 Coastlands Capital GP LLC /s/ Mark Shamia 12/11/2025 Coastlands Capital LLC /s/ Mark Shamia 12/11/2025 Matthew D. Perry /s/ Matthew D. Perry 12/11/2025