XLO · Xilio Therapeutics, Inc.

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.

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.

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.

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.

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.

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.

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.

The option was granted on April 15, 2026 and will vest in three equal installments on April 15, 2027, April 15, 2028 and April 15, 2029, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $8.6758 to $9.2499, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of securities sold at each separate price within the ranges set forth in this footnote (1) to this Form 4.

The number of shares beneficially owned reflects the 1-for-14 reverse stock split effected March 13, 2026.

The Prefunded Warrants are exercisable at any time on or after the date of issuance and have no expiration date. A holder of Prefunded Warrants may not exercise such warrants if, after giving effect to such exercise, the holder and its affiliates would beneficially own, for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, more than 19.99% of the outstanding shares of Common Stock of the Issuer.

The reported sale of 1,826 shares occurred automatically in a "sell to cover" transaction pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on April 8, 2024 solely to cover tax withholding obligations in connection with the vesting of restricted stock units.

The reported sale of 7,030 shares occurred automatically in a "sell to cover" transaction pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on April 8, 2024 solely to cover tax withholding obligations in connection with the vesting of restricted stock units.

Restricted stock units ("RSUs") convert to stock on a one-for-one basis.

Restricted stock units ("RSUs") convert to stock on a one-for-one basis.

Restricted stock units ("RSUs") convert to stock on a one-for-one basis.

Restricted stock units ("RSUs") convert to stock on a one-for-one basis.

These RSUs were granted on January 1, 2024 and vest in four equal annual installments beginning on January 1, 2025.

Restricted stock units ("RSUs") convert to stock on a one-for-one basis.

These RSUs were granted on January 1, 2024 and vest in four equal annual installments beginning on January 1, 2025.

Restricted stock units ("RSUs") convert to stock on a one-for-one basis.

Restricted stock units ("RSUs") convert to stock on a one-for-one basis.

These RSUs were granted on January 1, 2024 and vest in four equal annual installments beginning on January 1, 2025.

Restricted stock units ("RSUs") convert to stock on a one-for-one basis.

These RSUs were granted on January 1, 2024 and vest in four equal annual installments beginning on January 1, 2025.

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 3 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. On December 31, 2025, the performance criteria for a portion of the Tranche 3 Options was met.

The portion of Tranche 3 Options that achieved the vesting condition is equal to the percentage of the Series B Warrants exercised and/or cancelled due to the receipt by Xilio Therapeutics, Inc. of Non-Dilutive Capital (as defined in the Series B Warrants) by December 31, 2025.

This option vests in three (3) equal annual installments over the three-year period beginning on December 31, 2025, subject to the Reporting Person's continued service to the registrant through each applicable vesting date.

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 3 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. On December 31, 2025, the performance criteria for a portion of the Tranche 3 Options was met.

The portion of Tranche 3 Options that achieved the vesting condition s equal to the percentage of the Series B Warrants exercised and/or cancelled due to the receipt by Xilio Therapeutics, Inc. of Non-Dilutive Capital (as defined in the Series B Warrants) by December 31, 2025.

This option vests in three (3) equal annual installments over the three-year period beginning on December 31, 2025, subject to the Reporting Person's continued service to the registrant through each applicable vesting date.

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 3 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. On December 31, 2025, the performance criteria for a portion of the Tranche 3 Options was met.

The portion of Tranche 3 Options that achieved the vesting condition is equal to the percentage of the Series B Warrants exercised and/or cancelled due to the receipt by Xilio Therapeutics, Inc. of Non-Dilutive Capital (as defined in the Series B Warrants) by December 31, 2025.

This option vests in three (3) equal annual installments over the three-year period beginning on December 31, 2025, subject to the Reporting Person's continued service to the registrant through each applicable vesting date.

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 3 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. On December 31, 2025, the performance criteria for a portion of the Tranche 3 Options was met.

The portion of Tranche 3 Options that achieved the vesting condition is equal to the percentage of the Series B Warrants exercised and/or cancelled due to the receipt by Xilio Therapeutics, Inc. of Non-Dilutive Capital (as defined in the Series B Warrants) by December 31, 2025.

This option vests in three (3) equal annual installments over the three-year period beginning on December 31, 2025, subject to the Reporting Person's continued service to the registrant through each applicable vesting date.

The Reporting Person acquired 13,335,000 Prefunded Warrants upon the exercise of an equal number of Series B Warrants at an exercise price of $0.7499 per warrant. A holder of either such warrant may not exercise such warrant if, after giving effect to such exercise, the holder and its affiliates would beneficially own, for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, more than 19.99% of the outstanding shares of Common Stock of the Issuer (the "Common Stock").

The Prefunded Warrants are exercisable at any time on or after the date of issuance and have no expiration date.

The Reporting Person acquired 13,335,000 Prefunded Warrants upon the exercise of an equal number of Series B Warrants at an exercise price of $0.7499 per warrant. A holder of either such warrant may not exercise such warrant if, after giving effect to such exercise, the holder and its affiliates would beneficially own, for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, more than 19.99% of the outstanding shares of Common Stock of the Issuer (the "Common Stock").

The exercise price of the Series B Warrants was $0.75 per share of Common Stock. Because the Reporting Person chose to receive Prefunded Warrants in lieu of Common Stock upon exercise of the Series B Warrants, the exercise price was $0.75 less $0.0001 per share.

The Series B Warrants were exercisable at any time on or after November 1, 2025 and would have expired on December 2, 2025, provided that if the closing price of the Common Stock was below the exercise price on such date, the exercise price would have reset to the closing price on December 1, 2025 and the expiration time would have been extended to December 31, 2025.

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 $1.50 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.

Immediately exercisable.

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 $1.50 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.

Immediately exercisable.

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 $1.50 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.

This option was granted on February 22, 2022. The shares underlying the option began vesting on March 1, 2022 and continue to vest in equal monthly installments thereafter through February 1, 2026.

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.

The options vest 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.

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.

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.

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 $1.50 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.

This option was granted on February 22, 2022. The shares underlying the option began vesting on March 1, 2022 and continue to vest in equal monthly installments thereafter through February 1, 2026.

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 $1.50 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.

This option was granted on February 22, 2022. The shares underlying the option began vesting on March 1, 2022 and continue to vest in equal monthly installments thereafter through February 1, 2026.

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 $1.50 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.

Immediately exercisable.

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 $1.50 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.

This option was granted on September 5, 2023. The shares underlying the option began vesting on October 1, 2023 and continue to vest in equal monthly installments thereafter through September 1, 2027.

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 $1.50 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.

Immediately exercisable.

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.

Immediately exercisable.

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 $1.50 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.

Immediately exercisable.

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 $1.50 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.

Immediately exercisable.

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.

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.

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 $1.50 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.

This option was granted on August 3, 2023. The shares underlying the option began vesting on September 1, 2023 and continue to vest in equal monthly installments thereafter through August 1, 2027.

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.

The options vest 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.

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 $1.50 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.

Immediately exercisable.

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 $1.50 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.

This option was granted on January 1, 2023. The shares underlying the option began vesting on February 1, 2023 and continue to vest in equal monthly installments thereafter through January 1, 2027.

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.

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.

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.

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.

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 $1.50 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.

Immediately exercisable.

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 $1.50 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.

This option was granted on January 1, 2023. The shares underlying the option began vesting on February 1, 2023 and continue to vest in equal monthly installments thereafter through January 1, 2027.

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 $1.50 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.

Immediately exercisable.