# EDGAR Filing Document

**Accession Number:** 0001840233
**File Stem:** 0001193125-25-297207
**Filing Date:** 2025-11
**Character Count:** 8374
**Document Hash:** ba2b27fc678bd7d87f825de600c7ea61
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-297207.hdr.sgml**: 20251125

**ACCESSION NUMBER**: 0001193125-25-297207

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20251121

**FILED AS OF DATE**: 20251125

**DATE AS OF CHANGE**: 20251125

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Brennan Kevin M.
- **CENTRAL INDEX KEY:** 0001971303

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-40925
- **FILM NUMBER:** 251521175

**MAIL ADDRESS:**
- **STREET 1:** C/O XILIO THERAPEUTICS, INC.
- **STREET 2:** 828 WINTER STREET
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Xilio Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001840233
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 851623397
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 828 WINTER STREET
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451
- **BUSINESS PHONE:** 617-833-1027

**MAIL ADDRESS:**
- **STREET 1:** 828 WINTER STREET
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

[ ] Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Brennan Kevin M.<br><sub>(Last) (First) (Middle)</sub><br>828 WINTER STREET<br>SUITE 300<br><sub>(Street)</sub><br>WALTHAM, MA 02451<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-11-21 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [ ] 10% Owner<br>[X] Officer (give title below) [ ] Other (specify below)<br>_SVP, FINANCE AND ACCOUNTING_ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Xilio Therapeutics, Inc. [ XLO ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
|  |  |  |  |  |  |  |  |  |  |  |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| Stock Option (right to buy) | $0.841 | 2025-11-21<sup>(1)</sup> |  | A |  | 131700 |  | <sup>(2)</sup> | 2035-10-07 | Common Stock | 131700 | $0 | 131700 | D |  |
| Stock Option (right to buy) | $3.17 | 2025-11-21 |  | D |  |  | 55000 | <sup>(3)</sup> | 2033-03-31 | Common Stock | 55000 | <sup>(4)</sup> | 0 | D |  |
| Stock Option (right to buy) | $1.00 | 2025-11-21 |  | A |  | 55000 |  | <sup>(3)</sup> | 2033-03-31 | Common Stock | 55000 | <sup>(4)</sup> | 55000 | D |  |
| Stock Option (right to buy) | $2.785 | 2025-11-21 |  | D |  |  | 25000 | <sup>(5)</sup> | 2033-08-15 | Common Stock | 25000 | <sup>(4)</sup> | 0 | D |  |
| Stock Option (right to buy) | $1.00 | 2025-11-21 |  | A |  | 25000 |  | <sup>(5)</sup> | 2033-08-15 | Common Stock | 25000 | <sup>(4)</sup> | 25000 | D |  |
| Stock Option (right to buy) | $1.08 | 2025-11-21 |  | D |  |  | 20000 | <sup>(6)</sup> | 2034-04-30 | Common Stock | 20000 | <sup>(4)</sup> | 0 | D |  |
| Stock Option (right to buy) | $1.00 | 2025-11-21 |  | A |  | 20000 |  | <sup>(6)</sup> | 2034-04-30 | Common Stock | 20000 | <sup>(4)</sup> | 20000 | D |  |

---

### Footnotes:

(1) On October 8, 2025, the Board of Directors (the "Board") approved the adoption of the Xilio Therapeutics, Inc. 2025 Stock Incentive Plan (the "2025 Plan"), subject to stockholder approval of the adoption of the 2025 Plan. On October 8, 2025, the Compensation Committee of the Board granted these options (referred to as "Tranche 1 Options" in the 2025 Plan) to the Reporting Person, subject to stockholder approval of the adoption of the 2025 Plan. The stockholders approved the adoption of the 2025 Plan on November 21, 2025.

(2) This option vests in 36 equal monthly installments over the three-year period beginning on December 21, 2025, subject to the Reporting Person's continued service to the registrant through each applicable vesting date.

(3) This option was granted on April 1, 2023 and vested on March 30, 2024 with respect to 25% of the shares of common stock underlying the stock option. The remaining 75% of the shares of common stock underlying the stock option continues to vest in 36 equal monthly installments thereafter through March 30, 2027.

(4) The transactions reported herein reflect a one-time option repricing, effective on November 21, 2025, which reduced the exercise price of each repriced option to $1.00 per share unless such repriced stock option is exercised prior to November 21, 2026, in which case the original exercise price must be paid (the "Option Repricing"). Except as modified by the Option Repricing, all other terms and conditions of the repriced options, including, without limitation, any provisions with respect to vesting and expiration, remain in full force and effect.

(5) Immediately exercisable.

(6) This option was granted on May 1, 2024. The shares underlying the option began vesting on June 1, 2024 and continue to vest in equal monthly installments thereafter through May 1, 2028.

**Signature:** /s/ Kevin Brennan  
**Date:** 2025-11-25

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**