Dec 6 (Reuters) - Activist investor Engine Capital on Wednesday sent a letter to the board of cancer therapy developer 2seventy bio, urging a board refresh and the appointment of its chief operating officer Chip Baird as CEO, among other changes.

Engine Capital, which owns about a 3% stake in 2seventy bio, said the company should exclusively focus on its blood cancer therapy Abecma, and explore ways to "immediately cease or monetize all development programs".

2seventy bio did not immediately respond to a request for comment. (Reporting by Bhanvi Satija in Bengaluru; Editing by Krishna Chandra Eluri)