On Wednesday, the Food and Drug Administration (FDA) announced it had approved two new therapies for patients with metastatic or unresectable melanoma: Tafinlar (dabrafenib) and Mekinist (trametinib). The agency also greenlighted a diagnostic test that identifies tumors that express a certain tumor mutation, which could respond to these treatments
(FDA approves two drugs, companion diagnostic test for advanced skin cancer).
The two drugs, used as single therapies and not as a combination, target a specific tumor mutation called BRAF V600E. Mekinist additionally targets BRAF V600K. About half of melanomas express the BRAF mutation. Zelboraf (vemurafenib), which was approved in 2011 for metastatic melanoma, also targets BRAF.
The THxID BRAF diagnostic test will help identify patients who have tumors with the BRAF mutation and who will have a greater likelihood of responding favorably to either drug.
The BREAK-3 study confirmed that dabrafenib extended progression-free survival when compared with dacarbazine, an older chemotherapy drug (5.1 months versus 2.7 months). The phase 3 METRIC study found that trametinib extended progression-free survival to 4.8 months versus 1.5 months for patients who received dacarbazine or paclitaxel.
Both studies were presented at last year’s annual meeting of the American Society of Clinical Oncology (New Targeted Therapies for Advanced Melanoma Patients).
This year, melanoma advancements may again be a big research story with the addition of the PD-1 inhibitors (ASCO kicks off with promising immunotherapy studies).
Clinical studies are underway to look at combining the two new agents. An early-phase study showed promising results in delaying disease progression (Combined BRAF and MEK Inhibition in Melanoma with BRAF V600 Mutations).
Side effects of Tafinlar include non-melanoma skin cancer, headache, hair loss and rash on the hands and feet. Mekinist side effects included lung inflammation, rash, diarrhea and swelling.