Correlation of programmed death-ligand 1 expression with gene expression and clinicopathological parameters in Indian patients with non-small cell lung cancer

OBJECTIVES: The aim of this study is to evaluate the incidence of programmed cell death-ligand 1 (PD-L1) expression in non-small cell lung cancer (NSCLC) cases and its correlation with gene mutation and clinicopathological parameters. METHODS: Samples from NSCLCs patients were studied for PD-L1 expression through immunohistochemistry (IHC) using Rabbit anti-human PDL-1/CD274 Monoclonal Antibody. Genetic mutations were studied using IHC/fluorescence in situ hybridization (FISH) methods (for anaplastic lymphoma kinase [ALK]) or polymerase chain reaction/gene sequencing analysis (for epidermal growth factor receptor [EGFR]). Pearson's correlation coefficient (r) was used for correlation analysis. PD-L1 expression was analyzed for association with clinicopathological features. RESULTS: Of the 101 NSCLC cases, PD-L1 expression was observed in 33.66% (34/101) cases; tumor proportion score of <50%: 67.65% (23/34) and ≥50%: 32.35% (11/34) cases. PD-L1 positivity was seen in; males: 35.5%, females: 28%, smokers: 37.7%, cases with brain metastasis: 20%, cases with pleural effusion: 20.8%, and histopathological evaluation (well-differentiated: 21.42%, moderately-differentiated: 13.79%, poorly-differentiated: 36.11%, and adenosquamous disease: 40.9%). Genetic mutation studies revealed PD-L1 positivity in 18.1% cases with EGFR mutation, 50% of ALK-IHC positive cases, and 33.3% ALK-FISH positive cases. No or very weak correlation (r < 0.3) in PD-L1 expression with gene mutations or clinicopathological parameters was observed. CONCLUSIONS: The study demonstrated PD-L1 expression in ~ 1/3(rd) cases of NSCLC patients. No or very weak correlation was observed for PD-L1 expression with genetic mutations and other parameters studied. The presence of gene mutations in PD-L1 expressed samples suggests further investigation on PD-L1 inhibitors in such patients for decisive treatments.