Adjuvant Pembrolizumab for Resected NSCLC

For patients with stage IB–IIIA non–small-cell lung cancer (NSCLC), the survival benefit of standard treatment — resection followed by adjuvant platinum-based chemotherapy — has been modest.

To evaluate the use of immunotherapy in this setting with the PD-1 inhibitor pembrolizumab — standard treatment for patients with locally advanced or metastatic NSCLC — investigators conducted an industry-funded, international, randomized, phase III trial, in which 1177 patients (median age, 65; 68% men) with completely resected stage IB–IIIA NSCLC of any histology or PD-L1 expression level were assigned to receive pembrolizumab or placebo monotherapy. Most recipients had nonsquamous histology (62%–67%) and stage II disease (56%–58%) and had received prior adjuvant chemotherapy (86%). A similar number of patients in each arm had a PD-L1 tumor proportion score (TPS) of <1% (39%–40%), 1%–49% (32%), or ≥50% (28%).

At a median follow-up of 35.6 months, disease-free survival (DFS) in the overall population was significantly improved with pembrolizumab versus placebo (53.6 vs. 42.0 months; hazard ratio, 0.76; P=0.0014). However, DFS in patients with a PD-L1 TPS ≥50% was not significantly improved with pembrolizumab (HR, 0.82; P=0.14). Overall survival endpoints were immature. No new safety signals were observed. Pembrolizumab was associated with a higher rate of serious adverse events (AEs; 24% vs. 15%) and of AEs leading to discontinuation (20% vs. 6%) or interruption (38% vs. 25%); four treatment-related deaths occurred in the pembrolizumab arm.