CD274 and gastroesophageal junction adenocarcinoma: The phase III expansion of the trial will enroll 379 patients with locally advanced non-metastatic gastric and esophagogastric junction adenocarcinomas (≥cT2 and/or cN+) with at least one positive biomarker for immune response (MSI, PD-L1 CPS ≥ 1, TMB ≥ 10/MB or Epstein–Barr virus-positive, EBV+).