Unity Biotechnology (NASDAQ: UBX), a company developing drugs to treat diseases of aging, has appointed Anirvan Ghosh to serve as its CEO. He will succeed Keith Leonard, who the company says is leaving his executive position due to personal circumstances but will remain chairman of the board of directors. Ghosh is coming to San Francisco-based Unity from Biogen (NASDAQ: BIIB), where he is senior vice president and head of research and early development. Ghosh will start at Unity on March 30. Unity’s most advanced program, osteoarthritis drug UBX101, is currently in Phase 2 testing.