Programmed cell death ligand-1 (PD-L1) expression in extrahepatic biliary tract cancers: a comparative study using 22C3, SP263 and E1L3N anti-PD-L1 antibodies.

PD-L1 was expressed in a small subset of patients with bile duct cancer, and the percentage of positive tumour cells was low in PD-L1-positive cases. The SP263 assay showed the highest PD-L1 positivity in both tumour cells and immune cells, followed by the 22C3 and E1L3N assays. High PD-L1 expression was associated with a poor prognosis in extrahepatic bile duct cancer patients.