First-line (1L) nivolumab (NIVO) plus chemotherapy (chemo) vs chemo in patients (pts) with advanced gastric cancer, gastroesophageal junction cancer, and esophageal adenocarcinoma (GC/GEJC/EAC): 5-year (y) follow-up of Chinese pts from CheckMate 649.

392 Background: NIVO + chemo demonstrated clinically meaningful survival benefit and an acceptable safety profile vs chemo in previously untreated Chinese pts with advanced GC/GEJC/EAC from CheckMate 649, consistent with the overall study population. 1L NIVO + chemo is currently approved for pts with advanced non-HER2+ GC/GEJC/EAC in China and other countries. We report 5-y results of NIVO + chemo vs chemo in Chinese pts from CheckMate 649. Methods: Adults with previously untreated, unresectable advanced or metastatic, non-HER2+ GC/GEJC/EAC were enrolled regardless of programmed death ligand 1 (PD-L1) expression. Randomized pts received NIVO + chemo, NIVO + ipilimumab, or chemo. Dual primary endpoints for NIVO + chemo vs chemo were overall survival (OS) and progression-free survival (PFS) by blinded independent central review (BICR) in pts with PD-L1 combined positive score (CPS) ≥ 5. Results: 208 Chinese pts were randomized to NIVO + chemo or chemo. At 61-month (mo) minimum follow-up, NIVO + chemo continued to demonstrate OS and PFS benefit vs chemo in pts with PD-L1 CPS ≥ 5 and all randomized pts (Table). 5-y OS rate was 24% with NIVO + chemo vs 8% with chemo in pts with PD-L1 CPS ≥ 5 and 20% vs 7% in all randomized pts. Objective response rate (ORR) was higher and responses were more durable with NIVO + chemo vs chemo in pts with PD-L1 CPS ≥ 5 and all randomized pts (Table). No new safety signals were identified with longer follow-up. Conclusions: NIVO + chemo continued to demonstrate clinically meaningful long-term survival benefit, more durable responses, and acceptable safety vs chemo in Chinese pts after 5 y of follow-up, consistent with earlier reports and with the overall study population of pts with advanced non-HER2+ GC/GEJC/EAC. These results further support NIVO + chemo as a standard 1L treatment option for Chinese pts. Clinical trial information: NCT02872116 . Efficacy PD-L1 CPS ≥ 5 All randomized NIVO + chemo(n = 75) Chemo (n = 81) NIVO + chemo (n = 99) Chemo (n = 109) mOS (95% CI), mo 15.5(11.9–21.1) 9.6(8.0–12.1) 14.3(11.5–16.5) 10.3(8.1–12.1) HR (95% CI) 0.57 (0.40–0.82) 0.63 (0.46–0.85) mPFS a (95% CI), mo 8.5(6.0–14.0) 4.3(4.1–6.5) 8.3(6.2–12.4) 5.6(4.2–6.8) HR (95% CI) 0.51 (0.34–0.76) 0.57 (0.41–0.80) ORR a,b (95% CI), % 68 (56–79) 48 (36–60) 66 (55–76) 45 (35–56) mDOR a,c (95% CI), mo 12.5 (7.2–23.4) 6.9 (3.9–8.5) 12.5 (7.2–17.7) 5.6 (4.4–8.3) a Per BICR. b In pts with measurable target lesions at baseline. c In responders. DOR, duration of response; m, median.