Cullinan Therapeutics Inc

Adoption of 10b5-1 Trading Plans by Our Officers and Directors

During our fiscal quarter ended March 31, 2024, one of our officers (as defined in Rule 16a-1(f) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) entered into contracts, instructions or written plans for the purchase or sale of our securities that are intended to satisfy the conditions specified in Rule 10b5-1(c) under the Exchange Act for an affirmative defense against liability for trading in securities on the basis of material nonpublic information. We refer to these contracts, instructions, and written plans as “Rule 10b5-1 trading plans” and each one as a “Rule 10b5-1 trading plan.” We describe the material terms of the Rule 10b5-1 trading plan below.

Jennifer Michaelson, Chief Scientific Officer

On January 5, 2024, Jennifer Michaelson, our Chief Scientific Officer, entered into a Rule 10b5-1 trading plan that provides that Dr. Michaelson, acting through a broker, may sell up to an aggregate of 212,000 shares of our common stock. Sales of shares under the plan will begin no earlier than the later of (a) April 5, 2024 (the 91st day after the plan’s adoption) or (b) the earlier of (x) the third business day after our Quarterly Report on Form 10-Q for our fiscal quarter ended March 31, 2024 is filed with the SEC or (y) May 5, 2024 (the 121st day after the plan’s adoption). The plan is scheduled to terminate on November 1, 2025, subject to earlier termination upon the sale of all shares subject to the plan, or upon termination by Dr. Michaelson or the broker, or as otherwise provided in the plan.