Expression of Programmed Cell Death Ligand 1 and Mismatch Repair Status in Ovarian Carcinomas

Ovarian carcinoma is the third most common gynecological malignancy among women in India, with a poor prognosis despite advancements in treatment modalities. Immunotherapy, particularly the use of programd cell death ligand 1 (PD-L1) checkpoint inhibitors, has emerged as a promising approach. This study investigates the relationship between PD-L1 expression, mismatch repair (MMR) status, and clinicopathological features in epithelial ovarian carcinoma (EOC).

A cohort of 50 EOC cases was analyzed for PD-L1 expression in tumor cells and tumor-infiltrating lymphocytes (TILs) using immunohistochemistry (IHC). MMR status was also assessed through IHC. Statistical correlations between PD-L1 expression, MMR deficiency (dMMR), and clinicopathological parameters were evaluated.

PD-L1 expression in tumor cells and TILs was observed in 20% and 14% of cases, respectively. PD-L1 expression in tumor cells was absent in most advanced-stage tumors (stages III and IV) and cases with extraovarian spread. dMMR was identified in 30% (n = 15) of cases, predominantly in higher-stage tumors with extraovarian spread and significant TIL presence (P = 0.007). However, PD-L1 expression in tumor cells and TILs was absent in 86.7% and 80% of dMMR cases, respectively. No significant association was found between dMMR status and PD-L1 expression in EOC.

PD-L1 expression in tumor cells is predominantly observed in early-stage EOC, suggesting its potential as a prognostic marker and therapeutic target. Although dMMR status correlates with advanced-stage disease and TIL presence, it does not significantly influence PD-L1 expression in EOC. These findings highlight the importance of routinely assessing PD-L1 and MMR status to guide immunotherapeutic strategies in ovarian carcinoma.