The progress of immune checkpoint therapy in primary liver cancer

After years of in-depth research on immune checkpoints, therapeutic reversal of immune-exhaustion with immune checkpoint inhibitors (ICPIs) has been shown to be effective in primary liver cancer, including hepatocellular carcinoma and intrahepatic cholangiocarcinoma. The clinical development of novel ICPIs continues at a rapid pace, with more than 200 clinical trials of immunotherapeutic agents registered as of July 2021 for the treatment of liver cancer. In this review, we discussed the immune tolerance mechanism of liver cancer and the biological basis of immune checkpoints, focusing on the current status of ICPIs' development and clinical application. In addition, ICPIs combined with local resection, radiofrequency ablation, chemoembolization, and other molecular targeted drug therapies have shown better efficacy. Combined therapy based on multidisciplinary cooperation is the future direction of treatment in liver cancer.