RATIONALE-305: Efficacy, Safety, and Real-World Applicability of Tislelizumab + Chemotherapy in Gastric/GEJ Adenocarcinoma

This discussion provides a focused summary of the RATIONALE-305 trial, which evaluated tislelizumab in combination with platinum-based chemotherapy as first-line treatment for patients with previously untreated, HER2-negative gastric or gastroesophageal junction (GEJ) adenocarcinoma. The discussion highlights the global, randomized design of the study and its key finding: adding tislelizumab to chemotherapy produced a statistically significant improvement in overall survival compared with chemotherapy alone. The benefit was observed in the intent-to-treat population and was greater in tumors expressing PD-L1 based on the trial’s predefined TAP scoring. Experts also note that the safety profile of the tislelizumab regimen was manageable and consistent with expectations for PD-1 inhibitors plus chemotherapy, with no new or unexpected toxicities reported. Overall, the segment underscores how the results of RATIONALE-305 support the role of tislelizumab-based therapy as an important emerging option in first-line treatment of advanced gastric or GEJ adenocarcinoma.