Association of PD-L1 expression and PD-L1 gene polymorphism with poor prognosis in lung adenocarcinoma and squamous cell carcinoma

Programmed cell death 1 receptor (PD-1)/programmed death-1 ligand-1 (PD-L1) interaction has been linked to tumor immune evasion. PD-L1 expression has been indicated in identifying non-small cell lung carcinoma (NSCLC) patients for treatment with anti-PD-1 or anti-PD-L1 therapy. The goal of this study was to evaluate the clinicopathologic values of PD-L1 expression and single-nucleotide polymorphisms (SNPs) in the PD-L1 gene in lung adenocarcinoma (ADC) and squamous cell carcinoma (SqCC). The 147 NSCLC tissues consisted of 84 samples of ADC and 63 samples of SqCC. All tissue microarray paraffin blocks were used for PD-L1 immunohistochemical assays with 22C3, SP263, and SP142 clones. Three SNPs in the PD-L1 gene, rs4143815, rs822336, and rs822337, were genotyped using SNP pyrosequencing. The PD-L1 expression was significantly higher in SqCC than in ADC. Among ADCs, PD-L1 expression was significantly higher in papillary and solid types than in lepidic and acinar types. Statistical associations of the PD-L1 expression with a shorter disease-free survival outcome and lymph node metastasis in the ADCs were found but no associations in SqCCs. Among the three SNPs, the rs4143815 genotype CC was statistically associated with positive 22C3 PD-L1 labeling in NSCLCs. The rs4143815 genotype GG instead showed a trend of shorter survival outcomes but did not reach statistical significance in the ADCs. Our results showed a significantly higher prevalence of positive PD-L1 expression in lung SqCC than in ADC. However, the PD-L1 expression and rs4143815 genotype GG might be useful for the prediction of poor prognosis in lung ADC cases.