(Reuters) -U.S. drugmaker AbbVie said on Monday it will acquire cell therapy developer Capstan Therapeutics in a cash deal worth up to $2.1 billion.

Capstan develops CAR-T therapies, a type of treatment that uses a patient's own immune cells, specifically T cells, to fight diseases. Its main drug, CPTX2309, is currently in development for the treatment of autoimmune diseases.

AbbVie has been focusing on expanding its pipeline since its blockbuster arthritis drug, Humira, lost patent protection last year.