Abstract
Programmed death-1 (PD-1) is a coinhibitory inducible receptor present on T-cells and macrophages. Tumor cells with increased programmed death ligand-1 (PD-L1) are believed to escape immunity through activation of PD-1/PD-L1 pathway and suppression of effector-immune responses. Recent strategies targeting the PD-1/PD-L1 axis have shown promising results in patients with several tumors types, including lung carcinomas. Preliminary data suggest that PD-L1 protein expression might have predictive response to such therapies. Sarcomatoid carcinomas (SCs) of the lung include rare subtypes of poorly differentiated non-small-cell lung carcinomas of high grade and aggressive behavior. The biology of these neoplasms is poorly understood and they frequently show increased local inflammatory and lymphocytic infiltration. Here, we report the expression of PD-L1 in 13 SCs from two large retrospective lung cancer cohorts. Using automated quantitative immunofluoresence and a mouse monoclonal antibody directed against the extracellular domain of PD-L1, we show that 9 of 13 patients (69.2%) with SCs are positive for PD-L1 and their levels are higher than in conventional non-small-cell lung carcinoma. These results provide rationale for the potential use of targeted immunotherapy in lung SCs.