Pembrolizumab for Metastatic Non–Small-Cell Lung Cancer

The prior phase II KEYNOTE-021 study (Lancet Oncol 2016; 17:1497) showed that adding the PD-1 inhibitor pembrolizumab to first-line chemotherapy improved response rates in patients with advanced non–small-cell lung cancer (NSCLC).

To confirm these results, investigators conducted an industry-funded, randomized, double-blind, phase III study (KEYNOTE-189), in which 616 chemotherapy-naive patients with metastatic nonsquamous NSCLC were assigned 2:1 to receive platinum-pemetrexed with pembrolizumab or placebo for 4 cycles of therapy followed by maintenance pemetrexed with pembrolizumab or placebo for a total of up to 35 cycles. Patients who had disease progression with placebo were allowed to cross over to pembrolizumab monotherapy.

At median fo…