PDCD1 and gastroesophageal junction adenocarcinoma: This prospective, nonrandomized, open-label phase 2 trial (Chinese Clinical Trial Registry, ChiCTR2200061906) aimed to evaluate the effectiveness of adding the PD-1 antibody tislelizumab to perioperative chemotherapy in patients with locally advanced gastroesophageal junction adenocarcinoma (GEJA).