Programmed death-ligand 1 (PD-L1) expression in pleomorphic carcinoma of the lung

Background and ObjectivesPulmonary pleomorphic carcinoma (PPC) is a rare and aggressive subtype of lung cancer. Programmed cell death-ligand 1 (PD-L1) expression may be induced in a variety of malignant tumors, but its prognostic implication in PPC remains unclear. MethodsTwenty-six patients with surgically resected PPC were retrospectively reviewed. Immuno-histochemical staining was used to detect PD-L1 expression, and PD-L1 status was classified into high or low according to the percentage of tumor cells (TCs) expressing PD-L1 (tumor proportion score, TPS). ResultsPD-L1 expression was positive in 20 (76.9%) patients at the cut-off TPS value of 1%. A receiver-operating characteristic (ROC) analysis showed that the optimal cut-off value was 15% for prediction of cancer-specific death with the area under ROC curve of 0.701 (P=0.107). High PD-L1 expression was associated with a favorable overall survival (100% vs 45.9% at 5 years; P=0.046) as well as a favorable cancer-specific survival (88.9% vs 37.5% at 5 years; P=0.012). A multivariate analysis indicated a trend toward a favorable prognosis associated with high PD-L1 expression (hazard ratio [HR], 0.254 [95% confidence interval, 0.054-1.200]; P=0.084). ConclusionsPD-L1 expression was positive in most PPC cases, and high PD-L1 expression may predict a favorable prognosis in resected PPC.