MEK inhibitors under development for treatment of non-small-cell lung cancer

Introduction: The mitogen-activated protein kinase (MAPK) pathway is intimately implicated in the molecular pathogenesis of non-small-cell lung cancer (NSCLC). Aberrant MAPK signaling resulting from the upstream activating mutations converges on mitogen-activated protein kinase kinase 1/2 (MEK1/2), making MEK inhibition an attractive strategy for the treatment of NSCLC. Several MEK inhibitors have demonstrated anticancer activity in patients with NSCLC. Areas covered: In this article, we discuss the biological rationale for the use of MEK inhibitors and summarize the clinical experience with MEK1/2 inhibitors for the treatment of NSCLC, from initial phase I studies to phase II/III studies, both as monotherapy or in combination with other anticancer agents. Expert opinion: Trametinib in combination with the BRAF inhibitor dabrafenib represents the first MEK1/2 inhibitor containing regimen that is approved for advanced BRAF(V600E)-mutant NSCLC. Other MEK1/2 inhibitors that are also in advanced stages of clinical development include selumetinib, cobimetinib, and binimetinib. Several studies of MEK inhibitor combination therapies are underway, including trials using combined MEK inhibition and immune checkpoint blockade. Further research aimed at discovering biomarkers of response and resistance to MEK1/2 inhibitors will be needed to develop rational combination strategies for the treatment of NSCLC driven by aberrant MAPK signaling.