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

Pulmonary 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.

Twenty-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).

PD-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 (88.9% vs 37.5% at 5 years; P =.046) as well as a favorable cancer-specific (100% vs 45.9% at 5 years; P =.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).

PD-L1 expression was positive in most PPC cases, and high PD-L1 expression may predict a favorable prognosis in resected PPC.