First-line pembrolizumab ± chemotherapy for recurrent/metastatic head and neck cancer: Japanese subgroup of KEYNOTE-048

Background Here, we report the results of the Japanese subgroup of the phase 3 KEYNOTE-048 study of pembrolizumab alone, pembrolizumab plus platinum and 5-fluorouracil (pembrolizumab–chemotherapy), or cetuximab plus platinum and 5-fluorouracil (EXTREME) in previously untreated recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC). Methods Primary end points were overall survival (OS) and progression-free survival (PFS). Efficacy was evaluated in patients with PD-L1 combined positive score (CPS) ≥ 20 and ≥ 1 and the total Japanese subgroup ( n = 67). Results At data cutoff (25 February 2019), pembrolizumab led to longer OS versus EXTREME in the PD-L1 CPS ≥ 20 subgroup (median, 28.2 vs. 13.3 months; HR, 0.29 [95% CI 0.09–0.89]) and to similar OS in the total Japanese (23.4 vs. 13.6 months; HR, 0.51 [95% CI 0.25–1.05]) and CPS ≥ 1 subgroups (22.6 vs. 15.8 months; HR, 0.66 [95% CI 0.31–1.41]). Pembrolizumab–chemotherapy led to similar OS versus EXTREME in the PD-L1 CPS ≥ 20 (median, 18.1 vs. 15.8 months; HR, 0.72 [95% CI 0.23–2.19]), CPS ≥ 1 (12.6 vs. 15.8 months; HR, 1.19 [95% CI 0.55–2.58]), and total Japanese subgroups (12.6 vs. 13.3 months; unadjusted HR, 1.10 [95% CI 0.55–2.22]). Median PFS was similar for pembrolizumab and pembrolizumab–chemotherapy versus EXTREME in all subgroups. Grades 3–5 treatment-related adverse events occurred in 5 (22%), 19 (76%), and 17 (89%) patients receiving pembrolizumab, pembrolizumab–chemotherapy, and EXTREME, respectively. One patient receiving pembrolizumab–chemotherapy died because of treatment-related pneumonitis. Conclusion These results support the use of first-line pembrolizumab and pembrolizumab–chemotherapy for Japanese patients with R/M HNSCC. Clinical trial registry ClinicalTrials.gov, NCT02358031.