Correlation Between PD-L1 Expression and Clinicopathologic Features in 404 Patients with Lung Adenocarcinoma

PD-1/PD-L1 inhibitors is the important drugs of immunotherapy for malignant tumors. PD-L1 expression is an important biomarker of selecting patients for ICIs therapy. However, the correlation of PD-L1 expression with clinicopathologic features in lung adenocarcinoma remains controversial.

PD-L1 expression was tested using clone SP263 by immunohistochemistry (IHC) on Ventana automated Benchmark in tissue micro-arrays (TMA) in lung adenocarcinoma. The association of PD-L1 expression with clinicopathologic characteristics, including gender, age, histological subtype, smoking history, stage, and genotype were analyzed.

404 patients were available for analyzing. The incidence of PD-L1 expression was 22.5% (using a cutoff of ≥ 25%). Statistical analysis showed PD-L1 expression was associated with advanced stage, lymph node (LN) metastasis, solid predominant subtype and wild-type epidermal growth factor receptor (EGFR) gene. In subgroup analysis, PD-L1 expression in patients with EGFR exon 19 deletions was higher than that of with EGFR L858R mutation at exon 21 (21.6% vs. 10.2%, P = 0.046). In multivariate analysis for overall survival (OS) by Cox hazard proportion model, patients with EGFR gene mutations (HR 1.635, 95% CI 1.310-2.040, P < 0.001) and early stage (HR 2.495, 95% CI 2.003-3.106, P < 0.001) had a longer survival, while PD-L1 expression was not associated with overall survival (HR 0.847, 95% CI 0.655-1.094, P = 0.203).

For patients with lung adenocarcinoma, LN metastasis, wild-type EGFR, advanced stage, solid predominant subtype were independent predictors of PD-L1 expression by multivariate analysis. PD-L1 expression may be not a predictor of OS for patients with lung adenocarcinoma.