GEMSTONE-303: Prespecified progression-free survival (PFS) and overall survival (OS) final analyses of a phase III study of sugemalimab plus chemotherapy vs placebo plus chemotherapy in treatment-naïve advanced gastric or gastroesophageal junction (G/GEJ) adenocarcinoma (ESMO 2023)
Methods Eligible pts with previously untreated, no known HER2-positive status, PD-L1 expression ≥5%, unresectable advanced or metastatic G/GEJ adenocarcinoma were randomized 1:1 to receive suge/placebo (1200 mg, Q3W, IV) + CAPOX (capecitabine, 1000 mg/m2, PO, BID, D1-14, Q3W; oxaliplatin, 130 mg/m2, IV, Q3W; max 6 cycles). Table: LBA79 PD-L1 Expression Level >=5% Suge+CAPOX Placebo+CAPOX N=241 N=238 PFS (Months) Median (95% CI) 7.62 (6.37, 7.89) 6.08 (5.06, 6.44) P-value =10% N=130 N=128 PFS (Months) Median (95% CI) 7.79 (6.77, 9.99) 5.52 (4.83, 6.67) P-value 0.0001 HR (95% CI) 0.58 (0.43, 0.77) OS (Months) Median (95% CI) 17.81 (14.36, 21.16) 12.45 (9.89, 13.86) P-value 0.0022 HR (95% CI) 0.64 (0.48, 0.85) Conclusions Sugemalimab in combination with CAPOX demonstrates statistically significant and clinically meaningful improvements in PFS and OS, with a manageable safety profile. These findings support suge+CAPOX as new first-line treatment option for pts with PD-L1 expression ≥5%, advanced G/GEJ adenocarcinoma.