Claudin 18 (CLDN18) is a member of the CLDN family of cell surface proteins and CLDN18 isoform 2 (CLDN18.2) is normally expressed only in the stomach; Sahin et al. reported that CLDN18.2 is activated in a wide range of human malignancies, especially gastric, esophageal, and pancreatic adenocarcinoma [17]. This evidence concerns the gene CLDN18 and pancreatic adenocarcinoma.