Clinical Development of BRAF plus MEK Inhibitor Combinations.

Genomic profiling shows that many solid tumors are characterized by specific driver aberrations, and this has expanded the therapeutic options for many patients. The mitogen-activated protein kinase (MAPK) pathway is a key cell signaling pathway involved in regulating cellular growth, proliferation, and survival. Driver mutations in the BRAF gene, a key player in the MAPK pathway, are described in multiple tumor types, including subsets of melanoma, non-small cell lung cancer (NSCLC), and anaplastic thyroid cancer (ATC), making BRAF a desirable target for inhibition. BRAF inhibitors have shown efficacy in several cancers; however, most patients eventually develop resistance. To delay or prevent resistance, combination therapy targeting BRAF and MEK, a downstream signaling target of BRAF in the MAPK pathway, was evaluated and demonstrated synergistic benefit. BRAF and MEK inhibitor combinations have been approved for use in various cancers by the US FDA. We review the clinical data for various BRAF plus MEK combination regimens in three cancer types with underlying BRAF driver mutations: melanoma, NSCLC, and ATC. We also discuss practical treatment considerations and management of selected combination therapy toxicities.