Standardized interpretation criteria for predictive PD-L1 testing are still matter of debate, and data of comprehensive and well-characterized cohorts are not available for rare cancer types [10], including cholangiocarcinoma (CCA), which is a heterogeneous group of malignancies that can emerge at any location in the biliary tree, from the smallest intrahepatic  bile ducts (Canaliculi biliferi) to the distal choledochal duct. The gene discussed is CD274; the disease is cancer.