Ipilimumab is one of a class of drugs called monoclonal antibodies, which stimulate the body's own immune system to fight disease. The experimental treatment is being developed by Bristol-Myers Squibb and Medarex, a US biotech company. The drug is being trialled on malignant melanoma, the most serious form of skin cancer, Hodgkin's disease, lung cancer and prostate cancer. Studies are most advanced in melanoma, where it has been shown to prolong survival in patients with advanced forms of the disease. In the Mayo Clinic study of prostate cancer, researchers say that standard hormone treatment ignited the immune response, and adding ipilimumab was like "pouring gasoline on the pilot light".
Apparently it caused remarkable recession in several men's prostate cancers. During surgery the pathologists were having a hard time finding any remaining cancer cells.