HealthDay News — The FDA has approved two new drugs, dabrafenib (Tafinlar) and trametinib (Mekinist), to treat metastatic or inoperable melanoma, along with a companion diagnostic test to determine whether the cancer is susceptible to the medications.

Dabrafenib inhibits BRAF genes that carry the V600E mutation, whereas trametinib inhibits MEK and is effective against melanomas with either the V600E or V600K mutations. The diagnostic product, THxID BRAF test, detects these mutations.

More than 76,000 people are expected to be diagnosed with melanoma this year, and about 9,480 are expected to die from it, the FDA said in a news release. About half of these patients have BRAF mutations.

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Although dabrafenib and trametinib have been granted approval as separate stand-alone drugs, clinical trials have evaluated both drugs together, and show the combination appears to be more affective than dabrafenib alone.

The THxID BRAF test was evaluated in the same clinical trials as dabrafenib and trametinib, and was used to select patients for the the trials, the FDA noted.

The dabrafenib trial involved 250 patients randomly assigned to receive either the investigational medication or standard chemotherapy with dacarbazine. In that study, dabrafenib prolonged progression-free survival 2.4 months.

The trametinib trial involved 322 patients and showed the medication extended progression free survival 3.3 months compared with standard chemotherapy. However, patients previously treated with other BRAF inhibitors, including dabrafenib, did not benefit from treatment with trametinib.

Adverse events for dabrafenib included hyperkeratosis, headache, fever, arthralgia, alopeica, hand-foot syndrome and noncancerous skin lesions. Some patients experienced more serious side effects, including cutaneous squamous cell carcinoma, hypotensive fever, dehydration, rigors, kidney failure and hyperglycemia requiring treatment with antidiabetic drugs.

The most serious side effects with trametinib included heart failure, lung inflammation, skin infection and loss of vision. Less serious side effects were rash, diarrhea, peripheral edema and acne-like skin eruptions.

Both drugs may cause infertility or harm a developing fetus, the FDA said.

Dabrafenib and trametinib are marketed by GlaxoSmithKline. The THxID BRAF test is manufactured by bioMérieux.

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