Advances in Immunotherapy for Intrahepatic Cholangiocarcinoma.

Intrahepatic cholangiocarcinoma (iCCA) is a highly lethal and heterogeneous primary liver malignancy with a dismal prognosis. Approximately 70% of patients are diagnosed at locally advanced or metastatic stages, therefore missing the opportunity for curative surgery, and conventional chemotherapy offers limited survival benefits. Immunotherapy, especially immune checkpoint blockade, represents a promising strategy, yet its efficacy as monotherapy in iCCA remains modest primarily due to the profoundly immunosuppressive and desmoplastic tumor microenvironment. This review examines the immune cell infiltration landscape of iCCA, focusing on the distinct roles of lymphoid cells and myeloid cells in shaping immune evasion. We then analyze key factors affecting immune responses, such as tumor-intrinsic driver mutations, immune regulatory mechanisms, and acquired resistance. Furthermore, we summarize current clinical advances in iCCA immunotherapy, including immune checkpoint inhibitor monotherapy, bispecific antibodies, combination strategies with chemotherapy or targeted therapy, cancer vaccines, and adoptive cell therapy. Despite some progress, the overall response to immunotherapy remains suboptimal, and future strategies need to focus on deciphering context-specific resistance mechanisms and enhancing the tumor-specific immune response.