Promising skin cancer drug in the near horizon

By Dr. Ananya Mandal, MDAug 30 2010

A new drug has been developed to combat a deadly form of skin cancer – melanoma. The drug, PLX4032, was tested on 32 melanoma patients who had a key mutation in their tumors. 26 of these patients responded favorably says the study published in the New England Journal of Medicine.

Keiran Smalley of the Moffitt Cancer Center and Research Institute in Tampa, who was not involved in the study feels these findings are “remarkable” because patients in small, early trials such as this often get no benefit at all. Typically, experimental drugs shrink tumors in only 5% to 10% of patients.

Lynn Schuchter of the University of Pennsylvania, one of the study researchers said some patients began showing improvement within only a few days. In two of these patients tumors disappeared, and some patients' disease remains in check. It's too early to know whether patients will stay in remission, however. The median remission was more than seven months, the study says. Shrinking of tumors in this cancer is a rare feat, say researchers. This is especially true in advanced melanoma that has spread to other organs. The two approved drugs for melanoma — a chemotherapy called dacarbazine and an immune therapy called interleukin-2 — shrink tumors for only about 10% to 20% of patients, the study says.

The drug is said to benefit only about 50% of patients whose tumors have the mutations in a gene called BRAF, the study says. Patients who don't have the mutation get no benefit. Once the drug is approved doctors probably will need to test all patients with advanced melanoma for these mutations. A test such as this probably would cost a few hundred dollars, says the study's lead author, Keith Flaherty of Massachusetts General Hospital in Boston.

The new drug differs from other chemotherapeutic agents in providing “targeted therapy”, say researchers. It aims to block a specific mutation found only in certain melanoma cells. This leads to lesser side effects as the drug attacks only diseased cells. Patients can take PLX4032, a pill, at home.

However according to Vernon Sondak of the Moffitt Cancer Center and Research Institute in Tampa, who wasn't involved in the study, mild side effects can become bothersome over time. There may be fatigue, rash and joint pain, Sondak says.

The study was funded by the drug's co-developers, Plexxikon and Roche Pharmaceuticals.Large trials are underway to prove the effectiveness of the new drug. Roche Pharmaceuticals plans to apply for FDA approval in 2011, spokeswoman Amy Berry says. In June, PLX4032 was given “fast-track” status by the Food and Drug Administration — a process that helps speed up development of drugs that fill unmet needs.