Positive survival results for anti-CLDN18.2 therapy with zolbetuximab, a chimeric monoclonal antibody against CLDN18.2, in patients with locally advanced, unresectable, or metastatic G/GEJ adenocarcinoma with CLDN18 overexpression have been demonstrated in two phase 3 randomized clinical trials when combined with standard first-line chemotherapy [18,19]. This evidence concerns the gene CLDN18 and gastroesophageal junction adenocarcinoma.