LBA79 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

SOX, or perioperative SOX and underwent standard gastrectomy with D2 lymphadenectomy.The adjuvant CapOx group received 8 cycles of oxaliplatin (130 mg/m 2 , d1) with capecitabine (1000 mg/m 2 , bid, d1-14).The adjuvant SOX group received oxaliplatin and oral S-1 at a dose depending on body surface area (40-60 mg bid, d1-14).The perioperative SOX group received 3 cycles of preoperative SOX plus 5 cycles of postoperative SOX followed by 3 cycles of S-1 monotherapy.The primary endpoint was 3-year DFS, and second endpoints included 5yOS% and safety.Results: Between 08/2012 and 02/2017, 1022 patients were included in mITT population and analyzed.With a median follow up time of 62.8 months, 495 recurrences and 416 deaths were observed by 07/04/2022.Perioperative SOX improved 5yOS% compared with adjuvant CapOx (60.0% vs. 52.1%;HR 0.79, 95%CI [0.62-1.00];p¼0.049).Adjuvant SOX was not inferior to postoperative CapOx (61.0% vs. 52.1%;HR 0.77, 95%CI [0.61-0.98];p¼0.033).Perioperative SOX improved 5yDFS% compared with adjuvant CapOx (53.2% vs. 45.8%;HR 0.79, 95%CI [0.63-0.98];p¼0.034).Adjuvant SOX was not inferior to adjuvant CapOx (50.8% vs. 45.8%;HR 0.86, 95%CI [0.69-1.06];p¼0.164).No additional adverse events were observed. Conclusions:The update on the RESOLVE survival analysis revealed improved survival in patients with G/GOJ adenocarcinoma undergoing D2 gastrectomy with perioperative SOX therapy compared to adjuvant CapOx, and adjuvant SOX was not inferior to adjuvant CapOx.Clinical trial identification: NCT01534546.