Efficacy of immunotherapy in hepatocholangiocarcinoma (HCC-CC): Proof of concept.

e16194 Background: Hepatocholangiocarcinoma (HCC-CC) is a rare form of cancer with a poor prognosis. Of all primary liver cancers, the incidence of HCC-CC ranges from 0.4 to 14.2%. HCC-CC is a mixed carcinoma with findings of both hepatocellular carcinoma and cholangiocarcinoma. Immune checkpoint inhibitors are a potent first line treatment in hepatocellular carcinoma with multiple clinical trial showing effectiveness in cholangiocarcinoma. HCC-CC has limited proven treatment options as patients are generally excluded from clinical trials. In this study we reviewed outcomes of patients with HCC-CC who received immune checkpoint inhibitor in a single center. Methods: Records of patients who had a pathological confirmed HCC-CC by a subspecialized hepatic pathologist at the University of Kansas medical center were reviewed. We identified 6 patients with locally advanced unresectable or metastatic HCC-CC that received immune checkpoint inhibitor between February 2017 and January 2021. Baseline characteristics were obtained, as well as best response, line of therapy, and duration of response. Results: Of the six patients 4 (66%) received PD-1 inhibitor alone and 2 (34%) received combination therapy with CTLA-4 inhibitor for the treatment of HCC-CC. There were 3 (50%) females and 6 (100%) with prior hepatitis C infection. four (66%) patients had metastatic disease and 2 had locally unresectable advanced disease. Objective response rate was 83.3%. One patient achieved complete response and had a treatment holiday after receiving treatment for 2 years, and restarted immunotherapy upon relapse. Four patients had a partial response, of which two passed away after disease progression. One patient had stable disease on 2 different lines of immunotherapy then progressed. Of those who responded, one patient received immunotherapy, 3 (50%) received liver directed therapy and two received chemotherapy or Lenvatinib as first line treatment (Table). Conclusions: Immune checkpoint inhibitors demonstrate potential activity in patients with HCC-CC without unexpected side effect in this unmet need high-risk population. Larger studies are needed to confirm activity and efficacy in this setting.[Table: see text]