Targeted Gene Therapy May Offer Hope Against Melanoma
A new targeted gene therapy for advanced skin cancer is effective in majority.
Aug. 26, 2010— -- Gene targeting drug therapy may offer hope for those with difficult-to-treat advanced-stage skin cancer according to preliminary data published Wednesday in the New England Journal of Medicine.
While skin cancer is highly treatable when caught early, once it spreads to other parts of the body (metastasizes), current treatments are limited and are effective in only a fraction of patients. The chance of survival for patients with metastatic melanoma is usually nine months or less.
The new treatment targets a mutation of the protein BRAF, which causes it to become overactive and cancer-producing in over half of all melanomas. Treatment with the drug was able to shrink tumors and slow the progression of the disease for 81 percent of patients who carry that mutation.
"This type of treatment gets to the root of what caused the cancer," says lead author Dr. Keith Flaherty, and provides hope for patients who until now had few, if any effective treatment options. Flaherty is director of Developmental Therapeutics at the Massachusetts General Hospital Cancer Center
Though it is too early to tell what effect this treatment could have on the life expectancy of such patients, doctors are calling this drug a potentially life-saving breakthrough.
"This therapy results in dramatic responses for patients -- it's phenomenal. I've been taking care of patients with advanced melanoma for 25 years and this is one of the most important breakthroughs we've seen," says Dr. Lynn Schuchter, professor of medicine at the Abramson Cancer Center at the University of Pennsylvania. She administered this drug as part of the drug trials.
How Gene Targeting Works
There are currently only two FDA-approved drugs for metastatic melanoma: interleukin-2 and dacarbazine, both of which provide limited results at best.
Interleukin-2 works in very few cases and dacarbazine, a form of chemotherapy, has not been shown to improve survival, notes Dr. Kelly McMasters, professor of medicine at the University of Louisville Department of Surgery.
Genetically targeted treatment, however, attacks the problem in an entirely different way. Instead of acting broadly on the immune system or cell growth, scientists identify the specific genetic mutation that may have caused the cancer in the first place and find a way to suppress the actions of that mutation.
BRAF, the protein affected by Flaherty's treatment, is pathologically overactive in 8 percent of cancers and over half of all melanomas so the treatment works by blocking this overactivity.