Abstract OBJECTIVES Perioperative pembrolizumab plus neoadjuvant chemotherapy significantly improved outcomes versus neoadjuvant chemotherapy alone in early-stage, resectable, non–small-cell lung cancer in the phase 3 KEYNOTE-671 study. We report outcomes in participants with baseline clinical stage II disease. METHODS Participants with untreated, resectable, stage II–IIIB (N2) non–small-cell lung cancer were randomized 1:1 to receive pembrolizumab 200 mg or placebo every 3 weeks plus chemotherapy for 4 cycles, followed by surgery and adjuvant pembrolizumab or placebo for 13 cycles (⁓9 months). Exploratory analyses were performed in participants with clinical stage II disease. RESULTS Of 797 randomized participants, 239 had stage II disease (pembrolizumab plus chemotherapy, n = 118; chemotherapy only, n = 121). Median study follow-up at data cutoff (August 19, 2024) was 49.9 (range, 32.2–75.3) months. Among participants who underwent surgery, 94/99 (94.9%) had R0 resections in the pembrolizumab arm and 89/103 (86.4%) in the neoadjuvant chemotherapy only arm. Event-free survival (hazard ratio, 0.50; 95% CI, 0.34–0.74), overall survival (hazard ratio, 0.69; 95% CI, 0.43–1.11), major pathological response (difference, 25.7%; 95% CI, 15.3–35.9), and pathological complete response (difference, 21.3%; 95% CI, 13.2–30.2) were improved in the pembrolizumab arm. Grade 3–4 treatment-related adverse events occurred in 50.0% of participants treated with pembrolizumab plus chemotherapy and 40.5% with chemotherapy; no treatment-related adverse events led to death. CONCLUSIONS In participants with stage II non–small-cell lung cancer, perioperative pembrolizumab improved efficacy outcomes with manageable safety versus neoadjuvant chemotherapy alone, consistent with the overall KEYNOTE-671 population. These results support the use of this regimen in patients with stage II disease.
Tsuboi et al. (2026) studied this question.