Neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab compared with neoadjuvant chemotherapy alone in patients with early-stage non-small-cell lung cancer (KEYNOTE-671): a randomised, double-blind, placebo-controlled, phase 3 trial

Background At the first interim analysis of the KEYNOTE-671 trial, adding perioperative pembrolizumab to neoadjuvant chemotherapy significantly improved event-free survival in participants with early-stage non-small-cell lung cancer (NSCLC). We report overall survival and health-related quality of life outcomes from the second interim analysis. Methods KEYNOTE-671 was a global phase 3 trial done at 189 medical centres. Eligible participants (aged >= 18 years) with resectable stage II, IIIA, or IIIB (N2) NSCLC were randomly assigned (1:1) to four cycles of neoadjuvant pembrolizumab (200 mg administered intravenously every 3 weeks) plus cisplatin-based chemotherapy followed by surgery and 13 cycles of adjuvant pembrolizumab (200 mg administered intravenously every 3 weeks) or to four cycles of neoadjuvant placebo (administered intravenously every 3 weeks) plus cisplatin-based chemotherapy followed by surgery and 13 cycles of adjuvant placebo (administered intravenously every 3 weeks). Randomisation was done centrally using an interactive response technology system and was stratified by disease stage, PD-L1 expression, histology, and geographical region in blocks of four. Participants, investigators, and sponsor personnel were masked to treatment assignments; local pharmacists were unmasked to support treatment preparation. The dual primary endpoints were overall survival and event-free survival evaluated in the intention-to-treat population. This study is registered at ClinicalTrials.gov, NCT03425643, and is ongoing but closed to enrolment. Findings Between May 11, 2018, and Dec 15, 2021, 797 participants were randomly assigned to the pembrolizumab group (n=397) or the placebo group (n=400). Median study follow-up at the second interim analysis was 366 months (IQR 276-478). 36-month overall survival estimates were 71% (95% CI 66-76) in the pembrolizumab group and 64% (58-69) in the placebo group (hazard ratio 072 [95% CI 056-093]; one-sided p=00052; threshold, one-sided p=00054). Median event-free survival was 472 months (95% CI 329 to not reached) in the pembrolizumab group and 183 months (148-221) in the placebo group (hazard ratio 059 [95% CI 048-072]). In the as-treated population, grade 3-5 treatment-related adverse events occurred in 179 (45%) of 396 participants in the pembrolizumab group and in 151 (38%) of 399 participants in the placebo group. Treatment-related adverse events led to death in four (1%) participants in the pembrolizumab group and three (1%) participants in the placebo group. Interpretation The significant overall survival benefit of neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab compared with neoadjuvant chemotherapy alone coupled with a manageable safety profile support the use of perioperative pembrolizumab in patients with resectable, early-stage NSCLC.