An experimental immunotherapy may keep people with melanoma alive for up to 1 year, according to findings presented at the 2013 International Congress of the Society for Melanoma Research in Philadelphia, Pennsylvania. The drug (MK-3475) blocks a protein, called PD-1, that lets cancer cells evade the immune system. Researchers treated 135 people with MK-3475 and found that tumors shrank in 40% and disappeared in 9%. Altogether, this drug is being tested in more than 3,000 people with melanoma or breast, bladder, colorectal, or lung cancer. In addition, another experimental PD-1 blocker called nivolumab is being tested alone and in combination with the U.S. Food and Drug Administration (FDA)-approved Yervoy (ipilimumab) against melanoma and blood, breast, gastric, kidney, liver, lung, and pancreatic cancers.