Abstract
BACKGROUND/AIM: Claudin 18.2 (CLDN18.2) has emerged as a highly selective biomarker and its abnormal expression has been reported in various primary malignant tumors. Recently, CLDN18.2 has gained attention as both a prognostic biomarker and a potential therapeutic target in gastric and gastroesophageal junction cancer. The purpose of this study was to investigate CLDN18.2 expression in a large cohort of 168 prostate cancer (PC) tissues, assess its correlation with clinicopathological factors, and evaluate its potential as a therapeutic target for anti-CLDN18.2 therapy. MATERIALS AND METHODS: Immunohistochemical staining was conducted using an approved diagnostic CLDN18.2 immunohistochemistry protocol (Ventana, 43-14A clone). Interpretation was carried out following the general rules for staining evaluation. RESULTS: Non-neoplastic gastric mucosa, used as a positive control for CLDN18.2 immunostaining, exhibited strong membranous staining. In contrast, no CLDN18.2 expression was detected in normal ductal and acinar cells of prostate tissue, nor in any of the 168 variable PC tissues. CONCLUSION: CLDN18.2 is not expressed in normal prostate tissue or PC, suggesting that it is unlikely to serve as a prognostic marker or a potential target for immunotherapy in PC.