Application of immune checkpoint inhibitors in hepatobiliary cancers

Hepatobiliary cancers are primarily categorized into hepatocellular carcinoma (HCC) and biliary tract cancers (BTC). HCC is one of the most common malignant cancers, with increasing global incidence. Immune checkpoint inhibitors (ICIs) have changed the approach of HCC management in recent years. The combination of atezolizumab and bevacizumab has surpassed sorafenib as the standard regimen for first-line treatment of advanced unresectable HCC. However, the optimal choice for second-line treatment after initial treatment with ICIs lacks clinical trial confirmation. In addition, limited clinical trial data on ICIs combined with locoregional and perioperative therapies have been reported. Unlike HCC, clinical studies have found that immunotherapy is effective only for BTC with specific molecular markers. Moreover, the molecular characteristics governing immune responses and evasion remain unclear. This review provides information on the application of immunotherapy for HCC and prospects over the next few years. In addition, current evidence from clinical trials of BTC has made BTC immunotherapy a research hotspot again. Based on the findings in the literature, future clinical trials are being planned. Furthermore, biomarkers used in immunotherapies for hepatobiliary cancers that may shed light on the management of these diseases in the future were discussed.