PD-L1 gene polymorphism and high level of plasma soluble PD-L1 protein may be associated with non-small cell lung cancer

Background: PD-1 and its ligand PD-L1 belong to the co-inhibition molecules, which can downregulate immune responses. The PD-L1 polymorphism and the level of soluble PD-L1 (sPD-L1) were investigated in non-small cell lung cancer (NSCLC). Methods: A total of 288 NSCLC patients and 300 controls were enrolled. An A/C polymorphism at position 8923 in the PD-L1 gene was genotyped using the polymerase chain reaction-restriction fragment length polymorphism method. Results: The prevalence of the 8923C allele was significantly higher in NSCLC patients than controls (10.2% versus 5.3%, p = 0.002, odds ratio 2.03, 95% confidence interval 1.30-3.17; data were adjusted for age and sex). NSCLC patients also showed increased plasma levels of sPD-L1 compared to controls (1.92 ng/mL versus 0.91 ng/mL, p<0.001). Furthermore, lung adenocarcinoma patients had higher sPD-L1 levels than patients with squamous cell carcinoma (p<0.01). However, no association was observed between the different genetic variants and plasma concentrations of sPD-L1. Conclusions: The PD-L1 8923A/C polymorphism could be associated with increased susceptibility to NSCLC. Plasma levels of sPD-L1 are significantly increased in NSCLC patients, especially those with adenocarcinoma.