First-line pembrolizumab plus chemotherapy versus chemotherapy alone for advanced esophageal cancer: 5-year extended follow-up in the Japanese subgroup of KEYNOTE-590

BACKGROUND: After a median study follow-up of 36.6 months, first-line pembrolizumab plus chemotherapy numerically improved overall survival (OS) and progression-free survival (PFS) versus placebo plus chemotherapy in Japanese participants with advanced esophageal cancer in the phase 3 KEYNOTE-590 study. The 5-year follow-up is presented. METHODS: /day). Primary end points were OS and PFS per RECIST v1.1 by investigator; objective response rate (ORR) and safety were secondary. The data cutoff date was July 10, 2023. RESULTS: In total, 141 of 794... participants were enrolled in Japan. Median study follow-up was 60.6 months (range, 53.8-69.7). Median OS was 17.7 months (95% CI, 13.9-28.5) with pembrolizumab plus chemotherapy versus 11.7 months (95% CI, 9.5-19.0) with placebo plus chemotherapy (HR, 0.65; 95% CI, 0.45-0.94); 60-month rates were 24.0% and 8.5%. Median PFS was 6.3 months (95% CI, 6.0-8.2) versus 6.0 months (95% CI, 4.2-6.2) (HR, 0.57; 95% CI, 0.39-0.83); 60-month rates were 16.9% and 0%. ORRs were 56.8% (95% CI, 44.7-68.2) and 38.8% (95% CI, 27.1-51.5). The median DOR was 8.3 months for pembrolizumab plus chemotherapy and 6.1 months for placebo plus chemotherapy. No new treatment-related adverse events occurred since the prior analysis. CONCLUSIONS: After a median follow-up of 5 years, pembrolizumab plus chemotherapy continues to provide long-term survival outcomes among Japanese participants with advanced esophageal cancer. No new safety signals were observed. Clinical trial registration ClinicalTrials.gov, NCT03189719.