First-line nivolumab plus ipilimumab or chemotherapy versus chemotherapy alone in advanced esophageal squamous cell carcinoma: a Japanese subgroup analysis of open-label, phase 3 trial (CheckMate 648/ONO-4538-50)

Background: Programmed cell death 1 (PD-1)-based treatments are approved for several cancers. CheckMate 648, a global, phase 3 trial, showed that first-line nivolumab (anti-PD-1 antibody) plus ipilimumab (NIVO + IPI) or nivolumab plus chemotherapy (NIVO + Chemo) significantly increased survival in advanced esophageal squamous cell carcinoma (ESCC) without new safety signals versus chemotherapy alone (Chemo). Methods: We evaluated the Japanese subpopulation of CheckMate 648 (n = 394/970), randomized to receive first-line NIVO + IPI, NIVO + Chemo, or Chemo. Efficacy endpoints included overall survival (OS) and progression-free survival assessed by blinded independent central review in Japanese patients with tumor-cell programmed death-ligand 1 (PD-L1) expression ≥ 1% and in all randomized Japanese patients. Results: In the Japanese population, 131, 126, and 137 patients were treated with NIVO + IPI, NIVO + Chemo, and Chemo, and 66, 62, and 65 patients had tumor-cell PD-L1 ≥ 1%, respectively. In patients with tumor-cell PD-L1 ≥ 1%, median OS was numerically longer with NIVO + IPI (20.2 months; hazard ratio [95% CI], 0.46 [0.30–0.71]) and NIVO + Chemo (17.3 months; 0.53 [0.35–0.82]) versus Chemo (9.0 months). In all randomized patients, median OS was numerically longer with NIVO + IPI (17.6 months; 0.68 [0.51–0.92]) and NIVO + Chemo (15.5 months; 0.73 [0.54–0.99]) versus Chemo (11.0 months). Grade 3–4 treatment-related adverse events were reported in 37%, 49%, and 36% of all patients in the NIVO + IPI, NIVO + Chemo, and Chemo arms, respectively. Conclusion: Survival benefits with acceptable tolerability observed for NIVO + IPI and NIVO + Chemo treatments strongly support their use as a new standard first-line treatment in Japanese patients with advanced ESCC. ClinicalTrials.gov ID: NCT03143153.