New results from a phase 3 clinical trial may shut the door on the addition of progressive death–1 or PD–ligand 1 inhibitors to the combination of BRAF and MEK inhibitors for the treatment of BRAF V600–mutated melanoma.
The approach seemed promising, given the efficacy of PD-1 and PD-L1 inhibitors in metastatic melanoma, and the relatively short response times to BRAF and MEK inhibitors could potentially be supplemented by longer response times associated with PD-1 and PD-L1 inhibitors. The two categories also have different mechanisms of action and nonoverlapping toxicities, which led to an expectation that the combination would be well tolerated.
But the new study joins two previous randomized, controlled trials that also failed to show much clinical benefit. IMspire150 assigned BRAF V600–mutated melanoma patients to vemurafenib and cobimetinib plus the anti–PD-L1 antibody atezolizumab or placebo. The treatment arm had a small benefit in progression-free survival (hazard ratio, 0.78), which led to Food and Drug Administration approval of the combination, though there was no significant difference when the two cohorts were assessed by an independent review committee. The KEYNOTE-022 trial examined dabrafenib plus trametinib with or without the anti–PD-1 antibody pembrolizumaband found no difference in investigator-assessed progression free survival.
