Stock Option Grant to Director David S. Grayzel of Q32 Bio Inc.

On October 23, 2025, Q32 Bio Inc. granted 53,521 stock options to David S. Grayzel, a director of the company. The options, which are exercisable at $2.80 per share, will vest and become exercisable in full upon the earlier of October 23, 2026, or the date of the company's next annual meeting of stockholders, subject to Grayzel's continued service on the vesting date. The options expire on October 22, 2035. Grayzel disclaims ownership of the underlying shares for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, except to the extent of his pecuniary interest therein, if any. The proceeds from any sale of shares issued upon exercise of these options will be transferred to Atlas Venture Life Science Advisors, LLC.