Xilio Therapeutics, Inc.

The Company maintains a defined contribution savings plan for employees that is defined to qualify under Section 401(k) of the Internal Revenue Code, as amended, (the “401(k) Plan”) in which substantially all employees are eligible to participate. Under the 401(k) Plan, all employees who meet minimum age and service requirements may elect to defer a portion of their annual compensation on a pre-tax basis or post-tax basis, up to the maximum amount prescribed by statute. For each participating employee, the Company makes matching contributions equal to 100% of the first 3% of compensation contributed, plus 50% of the next 2% of compensation contributed, for a maximum of up to 4% of the employee’s eligible compensation. Matching contributions are fully vested at the time of contribution. The Company incurred expenses related to matching contributions on behalf of employees to the 401(k) Plan of $0.7 million and $0.6 million during the years ended December 31, 2025 and 2024, respectively.

14. Subsequent Events

February 2026 Follow-On Offering

In February 2026, the Company closed a follow-on offering of prefunded warrants and received gross proceeds of $40.0 million before deducting underwriting discounts and commissions and offering expenses payable by the Company. In connection with the offering, the Company issued prefunded warrants to purchase 5,341,404 shares of its common stock. Each prefunded warrant is exercisable forone share of the Company's common stock. The purchase price of each warrant was $7.4886. Each prefunded warrant has an exercise price of $0.0014 per share and will be exercisable from the date of issuance until fully exercised, subject to beneficial ownership limitations for each holder.