Role of the MEK Inhibitor Trametinib in the Treatment of Metastatic Melanoma

Approximately 50% of patients with cutaneous metastatic melanoma harbor a somatic BRAF mutation. BRAF inhibitors are now established in the treatment paradigm of BRAF mutant melanoma, following the approval of vemurafenib by the US FDA in 2011. The vast majority of patients obtain some degree of tumor shrinkage with oral BRAF inhibitors, and responses are often rapid. However, resistance inevitably develops, with a median progression-free survival of 5–7 months. The oral MEK inhibitor trametinib has also shown activity in BRAF mutant melanoma in Phase III trials. We review the rationale for treating BRAF mutant melanoma with trametinib, as single-agent therapy and in combination with BRAF inhibitors, as well as the clinical data to date.