PDCD1 and hepatocellular carcinoma: Notably, several immune checkpoint inhibitors, such as nivolumab (PD-1), ipilimumab (CTLA-4), pembrolizumab (PD-1), atezolizumab (PD-L1), sintilimab (PD-1), and camrelizumab (PD-1), have obtained approval in various countries and regions for the treatment of HCC.