PDCD1 and hepatocellular carcinoma: To date, the US FDA has approved the anti-PD-1 antibody pembrolizumab as monotherapy, as well as the combination of the anti-PD-1 antibody nivolumab and the anti-CTLA-4 antibody ipilimumab for the treatment of advanced HCC patients who have previously received sorafenib (as a second-line or later-line immunotherapy) [102, 103].