Correlation between the Expression of PD-L1 and Clinicopathological Parameters in Triple Negative Breast Cancer Patients

Abstract

Objective: Triple-negative breast cancer (TNBC) is a heterogenous group of tumors with no estrogen receptor (ER), progesterone receptor (PR)and Cerb-B2/HER2 expression. Programmed death ligand-1 (PD-L1) is a transmembrane protein located on both non-tumor and tumor cells and ithas been shown to be associated with the escape of tumor cells from the immune system. PD-L1-targeted therapy alone or in combination is now analternative strategy in several aggressive tumor types. In this respect, TNBC is a potential candidate having limited treatment options and poor outcome.Material and Methods: Sixty-one breast cancers with no expression of ER, PR and Cerb-B2/HER2 were chosen to study PD-L1 immunohistochemistry. PD-L1 staining and its correlation with main clinicopathological parameters were evaluated.Results: Th percentage of PD-L1 positivity was 37.7% and 47.5% in tumor and tumor microenvironment, respectively. Th positivity rate was higherin breast carcinomas with medullary features (83.3%) and metaplastic carcinoma (66.6%) subgroups. PD-L1 expression of tumors was positively correlated with their Ki-67 score and PD-L1 positivity of the tumor microenvironment. No signifiant relationship was found between the other variables.Conclusion: PD-L1 expression rate was remarkable both in the tumor and the tumor microenvironment of TNBCs. Larger cohorts of TNBCare required to further describe their PD-L1 expression characteristics and help standardize PD-L1 immunohistochemistry assays in these tumors.