On January 29, 2024, 2seventy bio, Inc. entered into an asset purchase agreement with Regeneron Pharmaceuticals, Inc. Subject to the terms and conditions of the Purchase Agreement, the Company has agreed to sell to Regeneron the Company's oncology and autoimmune research and development programs, clinical manufacturing capabilities, and related platform technologies (collectively, the Programs" and such assets, the Transferred Assets"). On January 29, 2024, Nick Leschly informed the Company of his resignation as the Company's chief executive officer effective upon the date of the Closing. Mr. Leschly will remain as a member of the Board and will succeed Daniel Lynch as Chair of the Board, effective as of the date of the Closing.

On January 29, 2024, in connection with Mr. Leschly's appointment as Chairperson of the Board, the Company entered into a Transitional Services Agreement with Mr. Leschly. Under the Transition Agreement, the Company will provide Mr. Leschly with an annual retainer of $200,000 for his service as Chair of the Board. On January 29, 2024, the Board appointed William D. Baird, III as the chief executive officer of the Company, effective as of the date of the Closing.

Mr. Baird will also serve as the Company's principal executive and as a member of the Board as a class I director. Mr. Baird, 52, has served as the Company's chief operating officer since September 2023 and prior to that served as the Company's chief financial officer since 2021. Previously, Mr. Baird served as chief financial officer of bluebird bio, Inc. from February 2019 until November 2021 and served as chief financial officer of Amicus Therapeutics, Inc. from April 2012 until February 2019.