Merrimack Pharmaceuticals, Inc. is a clinical stage biopharmaceutical company, which engages in discovering, developing, and commercializing medicines consisting of novel therapeutics paired with diagnostics for the treatment of cancer. Its pipeline includes MM-131, MM-141, and MM-310. The company was founded by Anthony J. Sinskey, Gavin MacBeath, and Ulrik B. Nielsen in 1993 and is headquartered in Cambridge, MA.