Rubius Therapeutics, Inc. On February 27, 2023 and February 28, 2023, Sir Jonathan R. Symonds and Catherine A. Sohn, respectively, each notified the Company of their respective resignations as members of the Company's board of directors (the “Board”), effective immediately. Neither of the resignations of Dr. Sohn and Sir Symonds resulted from any disagreement with the Company on any matter relating to the Company's operations, policies or practices. As previously disclosed by the Company's Current Report on Form 8-K filed with the Commission on February 6, 2023 (the “February 8-K”), Dannielle Appelhans' employment as the Company's Chief Executive Officer and President was expected to terminate no later than January 31, 2023, but in light of the Company's continued review of strategic alternatives, Ms. Appelhans agreed to continue to serve as the Company's Chief Executive Officer and President until no later than March 3, 2023 (the “Extension of Services Arrangement”).

Pursuant to the Extension of Services Arrangement, Ms. Appelhans' position as Chief Executive Officer and President of the Company terminated on March 3, 2023. Ms. Appelhans' termination was not due to any disagreement with the Company on any matter relating to the Company's operations, policies, or practices. On March 2, 2023, the Board appointed Craig Jalbert, age 61, as the Company's President, Treasurer, Corporate Secretary, and a Class I director, to fill the vacancy created by Ms. Appelhans' termination, effective March 4, 2023.

Mr. Jalbert will also serve as the Company's principal executive officer, and as its interim principal financial officer and principal accounting officer. The term of the Company's Class I directors, including Mr. Jalbert, expires on the date of the Company's annual meeting of stockholders to be held in 2025 or upon the election and qualification of successor directors. Mr. Jalbert has not been appointed to any committee of the Board and as of the date hereof is not expected to be appointed to any committee of the Board.

Mr. Jalbert has served as a principal of the Foxborough, Massachusetts accounting firm of Verdolino & Lowey, P.C. since 1987. For over 30 years he has focused his practice in distressed businesses and has served, and continues to serve, in the capacities of officer and director for numerous firms in their wind-down phases.