MA25.01 Pembrolizumab Plus Chemotherapy for Advanced NSCLC Without Tumor PD-L1 Expression: Pooled Analysis of KN021G, KN189 and KN407

Randomized studies have demonstrated that pembrolizumab plus chemotherapy improves OS, PFS, and ORR compared with chemotherapy alone in patients with advanced NSCLC regardless of tumor PD-L1 expression level. We present a post hoc pooled analysis of pembrolizumab plus chemotherapy versus chemotherapy alone in patients with advanced NSCLC and no PD-L1 expression (ie, TPS <1%), representing an area of unmet need. Patients enrolled in KEYNOTE-021 cohort G (nonsquamous; NCT02039674), KEYNOTE-189 (nonsquamous; NCT02578680), and KEYNOTE-407 (squamous; NCT02775435) were included. Patients with nonsquamous NSCLC were randomized to pemetrexed-platinum with or without pembrolizumab; those with squamous NSCLC were randomized to carboplatin-paclitaxel/nab-paclitaxel with or without pembrolizumab. OS, PFS, and ORR were evaluated for the pooled intent-to-treat population. Response was assessed per RECIST v1.1 by blinded independent central review. Across studies, PD-L1 expression was assessed centrally using PD-L1 IHC 22C3 pharmDx assay (Agilent Technologies, Carpinteria, CA). Analyses were descriptive. Of 1298 patients enrolled across the 3 trials, 428 (33%) had PD-L1 TPS <1% (pembrolizumab plus chemotherapy, n=243; chemotherapy alone, n=185) and were included in this analysis. 52% had nonsquamous histology, 63% had ECOG PS of 1. Median (range) follow-up at data cutoff was 10.2 (0.1‒34.9) months. OS, PFS, and ORR were improved with pembrolizumab plus chemotherapy versus chemotherapy alone (Table). Grade ≥3 AEs (all-cause) occurred in 68% of patients receiving pembrolizumab plus chemotherapy versus 72% receiving chemotherapy alone. Immune-mediated AEs and infusion reactions occurred in 26% who received pembrolizumab plus chemotherapy versus 12% who received chemotherapy alone. Our results highlight the clinically meaningful efficacy benefit and acceptable safety profile of pembrolizumab plus chemotherapy versus chemotherapy alone in patients with advanced NSCLC and no PD-L1 expression. Benefit was consistent with that observed in the overall study populations, suggesting pembrolizumab plus chemotherapy should be considered standard-of-care first-line therapy for all patients with NSCLC, irrespective of PD-L1 expression. Funding Source: Funding for this research was provided by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.