CD274 and cholangiocarcinoma: Immunotherapy has exhibited promise in several solid malignancies, and in the context of CCA, immune checkpoint inhibitors are particularly valuable for malignancies characterized by DNA with deficient mismatch repair (dMMR)/high microsatellite instability (MSI), programmed cell death 1 ligand 1 (PD-L1) overexpression, or high levels of tumor mutational burden (TMB-high) [107,108].