Using ctDNA to Guide Treatment Decisions for Stage III Gastric Cancer

The goal of this randomized, controlled phase III clinical trial is to evaluate whether combining Tislelizumab with standard SOX chemotherapy improves disease-free survival (DFS) compared to chemotherapy alone in patients with stage III gastric or gastroesophageal junction adenocarcinoma who are ctDNA-MRD positive after surgery. The study will enroll 416 patients across multiple centers and will compare outcomes between two groups: patients receiving tislelizumab plus SOX chemotherapy and those receiving standard SOX chemotherapy alone. The primary questions to be addressed are whether the combination therapy improves 1-year DFS rates and whether it demonstrates an acceptable safety profile. Participants will provide tissue and blood samples for ctDNA-MRD testing, undergo postoperative adjuvant therapy (chemotherapy ± immunotherapy), and complete regular follow-up visits to monitor treatment response and safety. The trial will assess key outcomes, including DFS, overall survival (OS), and ctDNA clearance rates, to determine the clinical benefit and safety of tislelizumab in this population.