PD-L1 gene copy number and promoter polymorphisms regulate PD-L1 expression in tumor cells of non-small cell lung cancer patients.

•The polymorphisms of PD-L1 gene and PD-L1 gene copy number could be responsible for PD-L1 mRNA and protein expression.•Patients with CC genotype in rs822335 had significantly (p = 0.043) higher percentage of tumor cells with PD-L1 expression (test with 22C3 antibody) than patients with CT or TT genotypes.•PD-L1 gene polymorphisms and PD-L1 gene copy number may be a predictor for PD-L1 protein expression on tumor cells.