KEYNOTE-189: Randomized, double-blind, phase 3 study of pembrolizumab (pembro) or placebo plus pemetrexed (pem) and platinum as first-line therapy for metastatic NSCLC

Background: The premise that chemotherapy and immunotherapy may provide greater benefit than pembro or chemotherapy alone was supported by KEYNOTE-021 cohort G, in which pembro + pem + carboplatin significantly improved ORR and PFS over pem + carboplatin in patients (pts) with advanced nonsquamous NSCLC. We present results of the KEYNOTE-189 study of pembro + pem-platinum vs placebo + pem-platinum as first-line therapy for metastatic nonsquamous NSCLC. Methods: Pts with previously untreated stage IV nonsquamous NSCLC, no EGFR or ALK alteration, and ECOG PS 0-1 were randomized 2:1 to 4 Q3W cycles of pembro 200 mg or placebo + pem 500 mg/m2 + carboplatin AUC 5 or cisplatin 75 mg/m2 followed by maintenance pembro or placebo + pem. Randomization was stratified by PD-L1 tumor proportion score (TPS; Results: 616 pts were randomized: 410 to pembro + pem + platinum (“pembro arm”), 206 to placebo + pem + platinum (“placebo arm”). 76.5% of treated pts in the pembro arm and 66.8% in the placebo arm received ≥5 cycles of pem. 88.1% of enrolled pts were current/former smokers, carboplatin was chosen for 72.2%, and 63.0% had TPS ≥1%. As of Nov 8, 2017, median follow-up was 10.5 mo (range 0.2-20.4), and 33.8% in the pembro arm vs 17.8% in the placebo arm remained on treatment. In the placebo arm, 67 pts crossed over in-study to pembro and 18 received anti-PD-(L)1 therapy outside the study (effective crossover rate: 41.3% in the ITT population, 50.0% when pts still on treatment excluded). Pembro + pem + platinum, improved OS (HR 0.49; 95% CI 0.38-0.64; P Conclusions: Pembro + pem + platinum provided superior OS, PFS, and ORR compared with placebo + pem + platinum and had a manageable safety profile in pts with previously untreated metastatic nonsquamous NSCLC without EGFR or ALK alterations. These data suggest first-line pembro + pem and platinum may be a new standard of care for this population. Citation Format: Leena Gandhi, Delvys Rodgriguez-Abreu, Shirish Gadgeel, Emilio Esteban, Enriqueta Felip, Flavia De Angelis, Manuel Domine, Philip Clingan, Maximilian J Hochmair, Steven Powell, Susanna Yee-Shan Cheng, Helge G Bischoff, Nir Peled, Francesco Grossi, Ross R Jennens, Martin Reck, Rina Hui, Edward B Garon, Michael Boyer, Belen Rubio-Viqueira, Silvia Novello, Takayasu Kurata, Jhanelle E Gray, John J Vida, Ziwen Wei, Jing Yang, Harry Raftopoulos, M. Catherine Pietanza, Marina C Garassino. KEYNOTE-189: Randomized, double-blind, phase 3 study of pembrolizumab (pembro) or placebo plus pemetrexed (pem) and platinum as first-line therapy for metastatic NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT075.