PDCD1 and cholangiocarcinoma: Notably, durvalumab, which is a selective, high-affinity human immunoglobulin G1 monoclonal antibody that inhibits programmed cell death protein-1 (PD-L1), binds to PD-1 and CD 80, combined with gemcitabine plus cisplatin is approved as a frontline treatment for advanced BTC.[9] However, owing to the low incidence of brain metastases in patients with CCA, there is a lack of clinical data on intracranial responses to durvalumab.