Background: NIVO + chemo and NIVO + IPI demonstrated superior overall survival (OS) vs chemo in CheckMate 648 (NCT03143153), leading to approvals in the US, EU, Japan, and other countries. We report longer follow-up results. Methods: Adults with previously untreated, unresectable advanced, recurrent, or metastatic ESCC were randomized to NIVO (240 mg Q2W) + chemo (fluorouracil + cisplatin Q4W), NIVO (3 mg/kg Q2W) + IPI (1 mg/kg Q6W) or chemo. Primary endpoints were OS and progression-free survival (PFS) per blinded independent central review (BICR). Hierarchical testing was done first in patients (pts) with tumor cell programmed death ligand 1 (PD-L1) ≥ 1%, then in all randomized pts. Results: 970 pts were randomized to NIVO + chemo, NIVO + IPI, or chemo. With 29-mo minimum follow-up, NIVO + chemo and NIVO + IPI continued to show improvement in OS vs chemo, including higher 24-mo OS rates, in pts with tumor cell PD-L1 ≥ 1% and all randomized pts. Responses were more durable and a larger proportion of responders had a duration of response (DOR) ≥ 24 mo with NIVO + chemo and NIVO + IPI vs chemo in pts with tumor cell PD-L1 ≥ 1% (22%, 36%, 13%, respectively) and all randomized pts (21%, 29%, 13%). Additional efficacy data by PD-L1 status will be presented. Any-grade treatment-related adverse events (TRAEs) occurred in 96% (grade 3/4, 49%) of pts with NIVO + chemo, 80% (33%) with NIVO + IPI, and 90% (36%) with chemo. Any-grade TRAEs leading to discontinuation occurred in 35% of pts with NIVO + chemo, 19% with NIVO + IPI, and 21% with chemo. Treatment-related deaths occurred in 2% of pts in each arm. Conclusions: NIVO + chemo and NIVO + IPI continued to demonstrate clinically meaningful survival benefit vs chemo, durable objective responses, and acceptable safety profiles with longer follow-up. This further supports each regimen as a new 1L treatment option for advanced ESCC. Clinical trial information: NCT03143153.

^aper BICR; ^bEvaluated in responders. ORR, objective response rate; m, median.