Melanoma Drug Combo Improves Survival With Decreased Side Effects

September 29, 2014
Davy James, Associate Editor

A combination of vemurafenib (Zelboraf) and experimental drug cobimetinib significantly reduces the development of secondary skin cancer.

A combination of vemurafenib (Zelboraf) and experimental drug cobimetinib was found to extend the survival of melanoma patients with fewer side effects than vemurafenib treatment alone.

In the study, which appeared online today in the New England Journal of Medicine, researchers concluded that the combination therapy more effectively blocks a BRAF gene mutation from signaling melanoma to grow continuously as a cancer. The combination was found to be more effective than vemurafenib alone, which cannot completely block the signal.

Approximately 50% of patients with metastatic melanoma have the BRAF protein mutation.

In previous studies, researchers described the mechanisms behind melanoma becoming resistant to treatment with vemurafenib alone and how adding a drug such as cobimetinib may prevent these mechanisms. Additionally, 25% of patients taking vemurafenib alone went on to develop secondary cancer.

"We wondered why it was that we were getting the melanoma to shrink, but another skin cancer was developing," said study co-author Antoni Ribas, MD.

The researchers examined data collected over a year from 495 patients at 135 sites in the United States, Australia, New Zealand, and Europe. The patients received vemurafenib twice daily in combination with cobimetinib, which was taken once daily for 21 days, followed by 7 days without treatment.

The results of the study showed the drug combination extended the duration of response to the treatment from a median of 6 months with vemurafenib alone to 9 months with both drugs combined.

Researchers also determined that taking vemurafenib in combination with cobimetinib decreased the development of secondary skin cancer.

Although the combination therapy reduced the development of secondary cancer, 20% of the patients still suffered from some type of adverse event while taking both drugs, which included diarrhea, rash, fatigue, and edema.

The FDA still needs to approve cobimetinib before patients with BRAF mutated metastatic melanoma can receive the drug combination.