Claudin 18 Immunohistochemistry Expression in Salivary Gland Neoplasms: Limited Potential as a Therapeutic Biomarker

Abstract Purpose Claudin 18 (CLDN18) is a protein that functions to maintain the integrity of tight junctions in epithelial cells. Recent development of anti-Claudin 18.2 targeted therapies have yielded positive survival outcomes for patients with Claudin 18 expression in gastric carcinomas. This study aims to investigate whether expression of Claudin 18 is present in a variety of benign and malignant salivary gland neoplasms. Methods Forty-eight cases of salivary gland neoplasms of various subtypes were included for this pilot study. Ancillary data including tumor location, grade, and stage of tumor as applicable was collected. Claudin 18 immunohistochemistry was performed on a representative tumor block of each case. Results No aberrant Claudin 18 expression was seen in the benign as well as malignant salivary gland neoplasms in this pilot study. Conclusions CLDN18 expression was uniformly absent across the tumor types, locations, grades, and stages represented in this cohort. The absence of expression in all cases indicates that Claudin 18 has limited potential as a therapeutic marker in patients with salivary gland neoplasms. This study contributes to the extremely limited literature regarding Claudin 18 expression within salivary gland neoplasms.