LOS ANGELES -- Two new drugs can significantly lengthen survival in patients with metastatic melanoma, the advanced and generally lethal form of skin cancer, researchers reported Sunday.
Results were so dramatic in a trial of one of the drugs that the study was halted early, researchers reported at a Chicago meeting of the American Society of Clinical Oncology. Studies on both drugs also were published online by the New England Journal of Medicine.
The aborted trial is notable because the experimental agent called PLX4032, or vemurafenib, is the first chemotherapy agent that is directed at a specific mutation involved in the formation of skin tumors.
The development of the drug "is a major defining moment that will have an important effect on survival and quality of life," wrote Dr. Marc E. Ernstoff, of the Dartmouth Medical School in Lebanon, N.H., in an editorial accompanying the report.
But the mutation targeted by the drug occurs in only 47 percent of melanoma patients, and the drug appears to help only about half of them.
Many of the rest may benefit from the second drug, called ipilimumab, or Yervoy, which stimulates the immune system to fight off the tumors.
Yervoy was approved by the Food and Drug Administration in March based on earlier results that showed it was more effective than a vaccine used to treat melanoma. The new findings reported Sunday showed that it also was better than the conventional chemotherapy.
The manufacturers of the two drugs are planning trials to use both of the agents together to see if the combination can improve outcomes even more.
The new findings are "absolutely a major breakthrough for patients who have metastatic or unresectable melanoma," said Dr. Sylvia Adams, a melanoma immunotherapy expert at the New York University School of Medicine and a spokeswoman for ASCO.
The American Cancer Society estimates that about 68,000 cases of melanoma are diagnosed in the U.S. each year, and that 8,700 people die from melanoma each year.
The incidence is increasing most rapidly among the elderly and among women ages 15 to 39, presumably because of excess exposure to ultraviolet radiation outdoors and in tanning salons.
The conventional treatment now is with a drug called dacarbazine, which produces a median survival of 5.6 to 7.8 months after treatment is begun.
The results from the new drug were so powerful that the study's data-monitoring committee recommended halting the study and giving vemurafenib to all of the patients.
The primary side effects were skin rashes, sensitivity to light and joint pain.
The chief drawback of the drugs is cost. Yervoy, manufactured by Bristol-Myers Squibb, costs $120,000 for a course of treatment. Roche and Plexxikon, Inc., a biotechnology company in Berkeley, which developed vemurafenib, are expected to apply to the FDA shortly for approval to market the drug but have not yet announced a price.
The studies were sponsored by the drug companies.