Immunohistochemical Analysis of Potential Therapeutic Targets PRAME, FOLR1, and CLDN18.2 in Salivary Gland Carcinomas

Abstract

Salivary gland carcinomas are rare, heterogeneous, and often resistant to conventional treatments, highlighting the need for new therapeutic strategies. This retrospective study evaluated the expression of three immunologically relevant biomarkers— PRAME, FOLR1, and CLDN18.2—as potential therapeutic targets in salivary gland carcinomas. Tumor samples from 54 pa tients with seven histological subtypes treated at Saarland University Medical Center between 2013 and 2023 were analyzed using immunohistochemistry and scored with the Immunoreactive Score. PRAME was strongly expressed in 89% of cases, while FOLR1 and CLDN18.2 showed markedly lower expression at 41% and 6%, respectively. High PRAME expression was significantly associated with the presence of distant metastases, regardless of histological subtype. Patients with low PRAME ex pression tended to have improved overall survival, as indicated by Kaplan–Meier analysis and Log- Rank testing. These findings suggest PRAME as a promising immunotherapeutic and diagnostic target for salivary gland carcinomas, particularly through T- cell- based therapies already under investigation in other malignancies such as acute myeloid leukemia. Further preclinical studies are needed to validate the functional and therapeutic significance of PRAME, FOLR1, and CLDN18.2 in this context.