The concomitant inhibition of both BRAF and MEK can produce a more durable and greater tumor response than BRAF monotherapy while reducing BRAF inhibitor-related toxicity. Further evidence of the benefits of combined MEK and BRAF inhibition have been provided by the CoBRIM trial in which median progression-free survival was significantly increased with vemurafenib plus cobimetinib compared with vemurafenib alone (9.9 vs 6.2 months; hazard ratio for death or progression: 0.51; 95% CI: 0.39-0.68; p < 0.001) in 495 patients with advanced BRAF-mutated melanoma. Overall survival data in the CoBRIM trial were immature at time of final progression-free survival analysis but showed an hazard ratio for death of 0.65 (95% CI: 0.42-1.00; p = 0.046; boundary p < 0.0000037). Combination therapy was well tolerated with a reduced incidence of cutaneous squamous-cell carcinoma/keratoacanthoma. This combination may be a starting point for novel combination strategies with immunotherapies and other targeted therapies.
Keywords: BRAF inhibitor; MEK inhibitor; cobimetinib; combination therapy; vemurafenib.