Correlation of Programmed Death Ligand-1 (PD-L1) Expression with Clinicopathological Features in Non-Small Cell Lung Carcinoma: Experience from a Tertiary Cancer Care Center in India

Abstract

Background: According to the GLOBOCAN 2018 report, the estimated incidence of lung cancer in India was 67,795 in both sexes. The treatment of advanced Non-small cell lung cancer (NSCLC) saw a major paradigm shift with recent advances in molecular-targeted therapy. Immune checkpoint blockade therapy is one such novel strategy with promising clinical benefits in advanced NSCLC. Programmed cell death receptor-1/Programmed cell death ligand-1 (PD-1/PD-L1) pathway is one such checkpoint and has thus become the current area of interest in the treatment of lung carcinoma. The PD-1/ PD-L1 pathway is under active investigation as it represents a promising therapeutic target in NSCLC. The expression of PD-L1 in tumor cells has been suggested as a predictive marker of the clinical response to PD-1/ PD-L1-targeted therapy. Methods: This study was carried out at the Department of Pathology, Health Care Global Specialty Hospital, Bangalore from May 2018 to May 2019. In this study, we analyzed pattern of PD-L1 expression by immunohistochemistry testing using our own Laboratory Developed Test (LDT) in NSCLC patients. Results: Our study group comprised 50 patients of NSCLC. Among our study population, 40% of the patients exhibited PD-L1 immunopositivity (≥1%) with 28% of them having any expression (TPS 1% - 49%) and 12% of them having a high expression (TPS ≥ 50%) of PD-L1. Majority of them exhibited adenocarcinoma type of NSCLC under which the solid subtype showed a direct correlation with PD-L1 positivity (p-value: 0.004) with a poorly differentiated tumor histology being common in our population in relation to PD-L1 positivity (p-value: 0.043). PD-L1 expression did not correlate with age, gender, smoking status or clinical stage in our study. No association was found between tumor histology (SCC or AC) and driver mutation status with expression of PD-L1 in the present study. Conclusions: In our study, PD-L1 immunopositivity was found in 40% of patients and majority of them exhibited adenocarcinoma type of NSCLC. There was no correlation of PD-L1 expresion with age, gender, clinical stage, smoking status and tumor histology.