Description of Business and Liquidity	6 Months Ended
Jun. 30, 2026
Description of Business, Liquidity and Going Concern
Description of Business and Liquidity	1. Description of Business and Liquidity Xilio Therapeutics, Inc. (“Xilio” or the “Company”) is a clinical-stage biotechnology company dedicated to discovering and developing masked immuno-oncology (“I-O”) therapies with the goal of significantly improving outcomes for people living with cancer without the systemic side effects of current I-O treatments. The Company was incorporated in Delaware in June 2020, and its headquarters are located in Waltham, Massachusetts. Since its inception, the Company has devoted substantially all of its financial resources and efforts to research and development activities. As of June 30, 2026, the Company had an accumulated deficit of $434.7 million and has incurred significant operating losses, including net losses of $15.9 million and $29.1 million for the six months ended June 30, 2026 and 2025, respectively. The Company expects its operating losses and negative operating cash flows to continue for the foreseeable future as it continues to advance its product candidates through clinical trials, maintains the infrastructure necessary to support these activities and continues to incur costs associated with operating as a public company. As of June 30, 2026, the Company had cash and cash equivalents of $136.0 million. Based on its current operating plans, the Company anticipates that its existing cash and cash equivalents as of June 30, 2026 will be sufficient to enable it to fund its operating expenses and capital expenditure requirements for at least twelve months from the date of the issuance of these condensed consolidated financial statements. However, the Company has based its estimates on assumptions that may prove to be wrong. If actual results differ from the Company’s estimates, the Company could exhaust its available capital resources sooner than it anticipates, in which case, the Company would be required to seek additional capital sooner or curtail planned activities to reduce operating expenses, which may have an adverse impact on the Company’s ability to achieve its business objectives.

Description of Business and Liquidity

6 Months Ended

Jun. 30, 2026

Description of Business, Liquidity and Going Concern

1. Description of Business and Liquidity

Xilio Therapeutics, Inc. (“Xilio” or the “Company”) is a clinical-stage biotechnology company dedicated to discovering and developing masked immuno-oncology (“I-O”) therapies with the goal of significantly improving outcomes for people living with cancer without the systemic side effects of current I-O treatments. The Company was incorporated in Delaware in June 2020, and its headquarters are located in Waltham, Massachusetts.

Since its inception, the Company has devoted substantially all of its financial resources and efforts to research and development activities. As of June 30, 2026, the Company had an accumulated deficit of $434.7 million and has incurred significant operating losses, including net losses of $15.9 million and $29.1 million for the six months ended June 30, 2026 and 2025, respectively. The Company expects its operating losses and negative operating cash flows to continue for the foreseeable future as it continues to advance its product candidates through clinical trials, maintains the infrastructure necessary to support these activities and continues to incur costs associated with operating as a public company.

As of June 30, 2026, the Company had cash and cash equivalents of $136.0 million. Based on its current operating plans, the Company anticipates that its existing cash and cash equivalents as of June 30, 2026 will be sufficient to enable it to fund its operating expenses and capital expenditure requirements for at least twelve months from the date of the issuance of these condensed consolidated financial statements.

However, the Company has based its estimates on assumptions that may prove to be wrong. If actual results differ from the Company’s estimates, the Company could exhaust its available capital resources sooner than it anticipates, in which case, the Company would be required to seek additional capital sooner or curtail planned activities to reduce operating expenses, which may have an adverse impact on the Company’s ability to achieve its business objectives.