Claudin 18.2 Expression in Gastric Adenocarcinomas in a Large Turkish Cohort

Background: Claudin 18.2 (CLDN18.2) is a tight junction protein expressed especially in gastric adenocarcinomas. The prognostic and clinicopathologic implications of CLDN18.2 expression is currently unknown. Zolbetuximab monoclonal antibody against CLDN18.2 is under investigation as a potential treatment for advanced gastric cancer (GC). We aimed to investigate the impact of CLDN18.2 expression in GC on prognosis and tumor features in a large Turkish cohort. Methods: Seven tissue microarrays (TMAs) containing 263 cases of GC were constructed. Assessment of CLDN18.2 expression was performed by immunohistochemistry, where it was scored as negative and positive. Results: 14.3% (37/258) of GCs were stained with anti-CLDN18.2 antibody. While 7.8% (20/258) of all cases were positive, 92.2% (238/258) were scored as negative. There was no statistically significant difference between the two groups in terms of patient features such as age or sex, tumor grade, TNM stage, histologic subtype or overall survival. Conclusion: CLDN18.2 expression was not associated with patient prognosis in the Turkish cohort. However, as this molecule is a potential therapeutic target, information about the impact of CLDN18.2 expression will be important in managing patients, therefore more studies are needed to learn more on the outcomes of CLDN18.2 expression on clinicopathologic features in GC.