Astellas Pharma has exercised a buy-out option to acquire all of Maxygen’s ownership interest in Perseid Therapeutics, the joint venture between Maxygen and Astellas, according to Fierce Biotech.  Maxygen and Perseid are based in Redwood City, Calif.

They formed the collaboration in 2009 to focus on the discovery and R&D of multiple protein pharmaceutical programs, including Maxygen's MAXY-4 program. The transaction is expected to close within three months.  

Astellas will pay Maxygen $76 million, and Perseid will become its wholly-owned subsidiary. In addition, Astellas will become sole owner of the MAXY-4 program. The MAXY-4 proteins are intended to reduce T-cell activation and lessen the immune response in rheumatoid arthritis and transplant rejection.