Both the drugs, trametinib and dabrafenib, from a British farmaceutical major were tested in advanced melanoma patients in trials, and the results were are presented at a meeting in Chicago of the American Society of Clinical Oncology.
It was found that about 80 per cent of patients with BRAF-mutated tumours given trametinib were alive after six months, compared with 67 per cent on chemotherapy used as a standard treatment.
Separately, GlaxoSmithKline's dabrafenib delayed the disease progression by 5.1 months, compared to 2.7 months for chemotherapy, said Dr Caroline Robert, lead investigator of the study.
"In melanoma, we are living something incredible," Dr Robert, head of dermatology at the Institut Gustave Roussy in Villejuif, France, was quoted as saying by the New York Times.
Cancer occurs through genetic changes in cells allowing tumour growth factor receptors that activate various pathways, including a protein known as MEK. It's believed that BRAF- mutated melanomas are dependent on MEK, which is needed to amplify the cancer's genetic signal.
The research followed an early-stage study in 77 patients that found the drugs used together resulted in fewer skin lesions than previously reported with Roche's Zelboraf, a therapy cleared last year that targets a mutant gene found in half of advanced melanoma cases.
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Zelboraf works well for many patients but the tumour can eventually become resistant to the drug. Also, blocking BRAF can cause secondary skin cancers, which are not as serious as melanoma and can be removed surgically, but are nonetheless undesirable, said Dr Robert.
Trametinib, a pill, is also meant only for patients with the BRAF mutation. But it blocks MEK that is just downstream of BRAF in the chain of signals that spur tumour growth, the researchers said.
Blocking MEK might be an alternative to blocking BRAF, and it does not cause the secondary skin cancers, Dr Robert said. Some early results suggest that BRAF inhibitors and MEK inhibitors might be used together. (More)