New Therapies Approved for Metastatic, Unresectable Melanoma

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RESEARCH TRIANGLE PARK, NC – Two new therapies, Tafinlar (dabrafenib) and Mekinist (trametinib), have been approved for patients with metastatic or unresectable melanoma, according to the Food and Drug Administration.

Tafinlar, a BRAF inhibitor, is approved to treat patients with melanoma whose tumors express the BRAF V600E gene mutation, while Mekinist, a MEK inhibitor, is approved to treat patients whose tumors express the BRAF V600E or V600K gene mutations. About half of melanomas have a BRAF gene mutation.

Tafinlar and Mekinist, both marketed by GlaxoSmithKline, based in Research Triangle Park, NC, are approved as single agents, not as a combination treatment. Both have a companion diagnostic, the THxID BRAF test, manufactured by bioMérieux of Grenoble, France, to identify mutations.

Tafinlar was studied in 250 patients with BRAF V600E gene mutation-positive metastatic or unresectable melanoma. Patients were randomly assigned to receive Tafinlar or the chemotherapy drug dacarbazine. Patients who took Tafinlar had a delay in tumor growth that was 2.4 months later than those receiving dacarbazine.

The most serious side effects reported in patients receiving Tafinlar included an increased risk of cutaneous squamous cell carcinoma, fevers that may be complicated by hypotension, severe rigors, dehydration, kidney failure and increased blood sugar levels requiring changes in diabetes medication or the need to start medicines to control diabetes. Common side effects included hyperkeratosis, headache, fever, joint pain, non-cancerous skin tumors, hair loss and hand-foot syndrome.

Mekinist was studied in 322 patients with metastatic or unresectable melanoma with the BRAF V600E or V600K gene mutation. Patients were randomly assigned to receive either Mekinist or chemotherapy. Patients receiving Mekinist had a delay in tumor growth that was 3.3 months later than those on chemotherapy. Patients who previously used Tafinlar or other inhibitors of BRAF did not appear to benefit from Mekinist.

The most serious side effects reported in patients receiving Mekinist included heart failure, lung inflammation, skin infections and loss of vision. Common side effects included rash, diarrhea, peripheral edema and skin breakouts that resemble acne.

The FDA cautioned that Tafinlar and Mekinist carry the potential to cause fetal harm and infertility in men.

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