Expression of Programmed Death Ligand 1 Is Associated with the Prognosis of Intrahepatic Cholangiocarcinoma

Background Programmed death ligand 1 (PD-L1) is expressed in many malignancies and plays a critical role in escape from immune surveillance through inhibition of its receptor programmed death 1. The role of PD-L1 in intrahepatic cholangiocarcinoma (ICC) and mechanisms of its regulation, however, remain largely unknown.