Correlation between the Expression of PD-L1 in Pleural Effusion of Lung Adenocarcinoma and the Clinicopathological Features and Molecular Changes

Abstract

Background and objective Pembrolizumab, an immunotherapy for advanced non-small cell lung cancer (NSCLC), needs to predict treatment response based on test results including immunohistochemistry (IHC), which detects the expression of programmed death ligand 1 (PD-L1). The aim of this study was to evaluate the feasibility of immunocytochemistry (ICC) in NSCLC cytology to detect PD-L1 and to investigate the correlation between PD-L1 expression and clinical pathology and molecular features. Methods Sixty cases of lung adenocarcinoma pleural cytology were collected and PD-L1 sp263 reagent was used for immunocytochemical staining according to the manufacturer's instructions. Next-generation sequencing (NGS) was performed on pleural cytology specimens to explore its correlation. Results Of the 60 cases of lung adenocarcinoma pleural effusion cell block, 35 cases were positive for PD-L1 expression, and the positive expression rate was 58.3%. The positive rate of PD-L1 expression in the specimens of our hospital was 33.3%, and there was no significant difference between the cytological specimens and the histological specimens (P>0.05). Of the 60 cytological specimens, 26 were tested for NGS, and 15 (57.7%) were found to have epidermal growth factor receptor (EGFR) mutations. No correlation was found between PD-L1 expression and EGFR mutation. The positive expression rate of PD-L1 were not correlated with the age and gender in the study population (P>0.05). Conclusion When no surgical specimens are available, pleural cytology cell block specimens can be used for immunocytochemical detection of PD-L1, and the results are feasible.

Keywords

• programmed death ligand 1
• immunocytochemistry
• lung adenocarcinoma
• pleural effusion cell block
• next-generation sequencing