Correlation of programmed death ligand-1 (PD-L1) expression with clinicopathological features in lung carcinoma in a Macedonian population

Abstract

Background & objectives: Programmed death ligand 1(PD-L1) expression is a predictive biomarker of the success of immunotherapy for lung cancer (LC) patients, yet its prognostic significance remains unclear. This study aims to determine the relationship between PD-L1 expression and clinicopathological features in LC patients. Methods: The expression of PD-L1 protein in 63 surgically resected LC was evaluated by immunohistochemistry using clone 22C3 (Agilent, DAKO). The PD-L1 expression was determined by the Tumour Proportion Score (TPS) and classified as negative (TPS<1%), low-expression (TPS=1-49%) and high-expression (TPS≥50%). The statistical significance of the correlation between the clinicopathological features and PD-L1 expression was determined by chi-square test. Results: Our study group comprised 52 male and 11 female patients, with a median age of 64 (range, 33-77). 33 (52.4%) of the patients exhibited PD-L1 immuno-positivity, with 23 (36%) of them having a low expression and 10 (16.6%) having a high expression of PD-L1. PD-L1 immunopositivity was significantly higher in squamous cell carcinomas (18/25; 72%) compared to adenocarcinomas (10/25; 40%) (p=0.023). PD-L1 expression was associated with the smoking status (p=0.0086) for the patients smoking more than 10 cigarettes per day, as well as with a higher level (>30%) of stromal tumour infiltrate lymphocytes (TILs) (p=0.049). No correlation was found between PD-L1 expression and other parameters such as patients’ age, gender, stage, tumour status, grade, lymph nodal status and lymphovascular invasion. Conclusion: This is the first local study to describe PD-L1 expression and its association with clinicopathological features in LC patients. Our preliminary results indicate that the PD-L1 protein expression in LC is associated with some clinicopathological characteristics, such as smoking status, histological type (higher expression in squamous cell carcinomas) and higher level of TILs. Further research should be performed to clarify the clinical relevance and prognostic significance of PD-L1 in LC patients.