New Melanoma Drugs Have Unprecedented Success Rates
The type of skin cancer known as melanoma has historically been one of the deadliest forms of cancer. Though a few drugs have helped extend the 5 and 10 year survival periods, news of two particular drugs presented at yesterday's annual meeting of the American Society of Clinical Oncology have sparked some real hope for the future.
One is a drug called PLX4032 (vemurafenib), the first drug developed to target melanoma specifically by going after a gene mutation (BRAF V600) known to coincide with the cancer in about 50 percent of the cases. The study was conducted by the makers of the drug, Genentech, with outside researchers from the University of Pennsylvania Abramson Cancer Center.
The first test of PLX4032 included 675 melanoma patients worldwide, with inoperable metastasized melanoma (unresectable stage IIIC or stage IV melanoma) and the gene mutation BRAF V600. The test population received vemurafenib tabs two times a day, while the control group received intravenous injections of the drug dacarbazine every 3 weeks. The vemurafenib results were so favorable, however, that at after 6 months of the experiments, those in the control group were switched to vemurafenib, as 84 percent of vemurafenib patients had survived, while only 64 percent of the dacarbazine survived.
A second drug, recently approved for use, does not target melanoma per se, but it targets the immune system to fight cancer and, thereby, to lengthen life. Tradenamed Yervoy by Bristol-Myers Squibb, ipilimumab is an immune protein that inhibits the molecule CTLA-4 from functioning. Since CTLA-4 prevents immune cells from overworking, quashing this response will encourage the body's immune cells to work harder to attack the cancerous cells.
Memorial Sloan-Kettering researchers, as well as scientists employed by Bristol-Myers, conducted the research on 502 dacarbazine patients. Half of the patients on dacarbazine treatment also received Yervoy, and the other half did not receive any additional treatment.
After one year, the survival rate of those on Yervoy and dacarbazine was 47 percent; survival rate in the dacarbazine-only group was 36 percent. After three years of study, survival in the first group was 21 percent and 12 percent in the second.
Both PLX4032 and Yervoy are totally new classes of drugs for treatment of melanoma. At one time a very rare form of cancer, melanoma has been increasing 3.1 percent annually since 1992. Caucasians and men over 50 are most at risk, but melanoma is increasing rapidly among young women.