161P Adjuvant tegafur/gimeracil/oteracil (S-1) versus platinum-based chemotherapies for resectable gastric cancer: Real-world experience and a propensity score matching analysis

Abstract

Background: Although FLOT has been recognized as the first choice for neoadjuvant chemotherapy in gastric or GEJ adenocarcinoma, its efficacy needs to be improved. Sintilimab, a fully human IgG4 monoclonal antibody that binds to programmed cell death receptor-1 (PD-1), has shown remarkable clinical efficacy in various cancers. We aimed to assess the activity and safety profile of the combination of FLOT and sintilimab for neoadjuvant treatment of gastric or GEJ adenocarcinoma. Methods: In this ongoing, single-arm, phase II study, we recruited patients from Henan Cancer Hospital in China with histopathologically diagnosed resectable gastric or GEJ adenocarcinoma who had clinical T3/N+ or higher stage. Patients were given 4 cycles of FLOT (docetaxel 50 mg/m 2 , oxaliplatin 80 mg/m 2 , leucovorin 200 mg/m 2 , fluorouracil 2600 mg/m 2 , 24-h infusion on day 1, q2w) in combination with 3 cycles of sintilimab (200mg, iv, d1, q3w), followed by surgery and 4 postoperative cycles of FLOT. The primary endpoint was pathological complete response (pCR). The secondary endpoints included major pathological remission (MPR) and objective response rate (ORR).