Programmed death-ligand 1 (PD-L1) expression in various tumor types

Background Programmed cell death-1 (PD-1) is a co-inhibitory receptor expressed on lymphoid and non-lymphoidderived cells that negatively regulates peripheral T-cell responses. PD-L1, the major PD-1 ligand, is expressed on various tumors and is being investigated as a possible predictive marker for anti-PD-1 therapy. Few studies have determined PD-L1 expression across tumor types using a consistent process. We evaluated PD-L1 expression across human tumor samples using a novel, automated, sensitive, and specific PD-L1 IHC assay (developed by Dako) using the 28-8 antibody.