Second-line pembrolizumab versus chemotherapy in Japanese patients with advanced esophageal cancer: subgroup analysis from KEYNOTE-181

Abstract Background Safe and effective treatments for advanced esophageal cancer are an unmet need in Japan. We report results of a subgroup analysis of Japanese patients enrolled in KEYNOTE-181, a randomized, open-label, phase 3 study of pembrolizumab versus chemotherapy as second-line therapy for patients with advanced or metastatic esophageal cancer whose disease progressed after standard first-line therapy. Methods Patients were randomly assigned 1:1 to receive pembrolizumab 200 mg every 3 weeks or investigator’s choice of paclitaxel, docetaxel, or irinotecan. Efficacy was evaluated in all Japanese patients and in those with programmed death ligand 1 combined positive score ≥ 10. Results Of the 152 Japanese patients enrolled (pembrolizumab, n = 77; chemotherapy, n = 75), 150 (98.7%) had squamous cell carcinoma and 79 (52.0%) had combined positive score ≥ 10. At the final analysis, median overall survival was improved among all patients (12.4 vs 8.2 months with pembrolizumab and chemotherapy, respectively; hazard ratio, 0.68; 95% CI 0.48–0.97) and patients with combined positive score ≥ 10 (12.6 vs 8.4 months; hazard ratio, 0.68; 95% CI 0.42–1.10). Fewer patients had any-grade (74.0% vs 95.9%) or grade 3–5 (16.9 vs 50.0%) treatment-related adverse events with pembrolizumab than with chemotherapy. Conclusion Consistent with the global trial results, second-line pembrolizumab therapy showed a survival benefit and a favorable safety profile compared with chemotherapy in Japanese patients with advanced esophageal cancer.