PDCD1 and hepatocellular carcinoma: In the comprehensive HCC treatment, monoclonal and bispecific antibodies targeting inhibitory pathways such as programmed cell death-1(PD-1), programmed cell death ligand 1 (PD-L1) and CTL antigen 4 (CTLA-4) have been demonstrated to activate the cytokines and cytotoxic mechanisms of adaptive immunity to override the resistance to cell death, eradicate cancer cells, and improve overall prognosis22, 28, 39, 40.