SILVER SPRING, Md., Nov. 11 (UPI/Stephen Feller) — The Food and Drug Administration has approved a new two-drug combination for metastatic melanoma after it was shown to be more effective at slowing the growth of tumors and preventing the growth of secondary tumors in some patients.
The combination was so effective with patients in a clinical trial the FDA granted it “priority review” status to speed its approval for use with patients.
Vemurafenib, sold as Zelboraf, is used to treat patients with melanoma that has spread to other parts of the body and whose tumors express a gene mutation called BRAF V600E. The mutation causes melanoma to grow continuously as a cancer, an effect not completely stopped by vemurafenib according to research.
Researchers at the University of California Los Angeles combined vemurafenib with cobimetinib, sold as Cotellic, that blocks an enzyme called MEK in another signalling pathway of cancer cells, restricting the ability of tumors to grow.
“[The] approval is a very significant advance in the treatment of metastatic melanoma,” Dr. Antoni Ribas, a researcher at UCLA, said in a press release. “For patients with a BRAF mutated melanoma, the combination has higher activity to shrink their tumors, and with less side effects than the drugs on their own.”
Researchers tested the two-drug combination in a randomized study with 495 patients who had previously untreated, BRAF V600 mutation-positive melanoma. In all cases, the cancer was either advanced or could not be removed with surgery.
All the patients received vemurafenib, and then were randomly given either cobimetinib or a placebo. The researchers reported that, on average, patients taking both drugs did not see their cancer worsen for 12.3 months after treatment, as opposed to just 7.2 months for patients only given vemurafenib.
Among patients given the combination, 70 percent saw complete or partial shrinkage of tumors, which only 50 percent of those taking vemurafenib and the placebo saw. Additionally, 65 percent of patients on the combination were still alive 17 months after starting treatment, while those only receiving vemurafenib had a 50 percent mortality rate.
A small subset of melanoma patients experience the growth of secondary tumors during treatment with vemurafenib — previous studies have shown it to be about 25 percent — however this decreased among patients who took both drugs in the clinical trial.
“As we continue to advance our knowledge of tumor biology, we have learned that cancer cells have a remarkable ability to adapt and become resistant to targeted therapies,” said Dr. Richard Pazdur, director of the office of hematology and oncology products at the FDA, in a press release. “Combining two or more treatments addressing different cancer-causing targets may help to address this challenge.”