ERBB2 and gastric cancer: Tislelizumab is a humanized immunoglobulin G4 (IgG4) anti-PD-1 monoclonal antibody recently approved for the treatment of HER2-negative GC/GEJC (in combination with platinum and fluoropyrimidine-based chemotherapy) in the US (in patients whose tumors express PD-L1 [≥ 1]) and EU (in patients whose tumors express PD-L1 Tumor Area Positivity [TAP] score ≥ 5%) [22, 23].