Liver immunotolerance and hepatocellular carcinoma: Patho-physiological mechanisms and therapeutic perspectives.

At the moment of the diagnosis of hepatocellular carcinoma (HCC), 70% of patients have only access to palliative treatments, with very few therapeutic options. Liver immunology is very specific, and liver immunotolerance is particularly developed because of the constant and massive influx of antigens. Deregulation of hepatic immunotolerance is implicated in chronic liver diseases development and particularly in liver carcinogenesis. For these reasons, HCC may be an excellent candidate for anticancer immunotherapies such as immune checkpoint inhibitors targeting CTLA-4 and PD-L1/PD-1. Nonetheless, because of the specific immune environment of the liver and the frequent association of HCC with hepatocellular insufficiency, the safety and the efficacy of these new treatments have to be properly studied in this situation. Thus, multiple phase II and III studies are in progress studying immune checkpoint inhibitor monotherapies, combination of different immunotherapies or local strategies such as transarterial chemoembolization combined with immune checkpoint inhibitors. Currently, only the final results of the tremelimumab phase II and the Nivolumab phase I/II study (CheckMate-040) are available. The latter is promising but need to be confirmed by the ongoing phase III studies to confirm the place of immunotherapy in the treatment of HCC. With many new molecular targets and therapeutic combination, immunotherapy represents a new hope in treating HCC patients although serious evaluation is still needed to confirm its interest.