Medarex is developing monoclonal antibodies to CTLA-4 and PD-1, which are proteins on the surface of T cells. T cells attack cancer cells, but CTLA-4 and PD-1 act as brakes on the T cell's anti-cancer activities. The monoclonal antibodies bind to those proteins, and release the T cell to attack cancer cells.
In 2011, the U.S. Food and Drug Administration approved Ipilimumab, a monoclonal antibody to CTLA-4, for treatment of metastatic melanoma. The cost is $120,000 for a cost of treatment.