On December 16, 2021, Dr. Nilesh Kumar, a member of the board of directors (the “Board”) of Checkmate Pharmaceuticals, Inc. (the “Company”), notified the Company of his intent to resign from the Board and the Compensation Committee of the Board, effective as of December 31, 2021. Dr. Kumar’s departure from the Board is due to a policy of his new employer that limits Dr. Kumar’s ability to serve on boards of publicly traded companies, not due to any disagreement with the Company or the Board on any matter relating to the operations, policies or practices of the Company. On December 16, 2021, the Board appointed Dr. Joy Yan, M.D., Ph.D. to fill the vacancy created Mr. Barry Labinger’s resignation. Dr. Yan will serve as a Class I director of the Company for a term expiring on the date of the Company’s annual meeting of stockholders to be held in 2024, or until her earlier death, resignation or removal. Dr. Yan, age 42, has served as the Chief Medical Officer of Ambrx Biopharma Inc. since October 2020. Prior to joining Ambrx, she served as Senior Clinical Lead, Team Leader in Oncology at Bristol Myers Squibb, from April 2017 to October 2020. Previously, she served as Director of Oncology Clinical Research at Janssen Pharmaceutical from September 2016 to April 2017. Before Janssen Pharmaceutical, she served as Director of Clinical Development at Bayer AG.