PDCD1 and hepatocellular carcinoma: Tislelizumab, a newly humanized IgG4 antibody against programmed cell death-1(PD-1), has been approved for the treatment of Hodgkin’s lymphoma (HL), and a large number of clinical studies, such as the Phase III clinical trial of sorafenib as a first-line treatment for HCC (NCT03412773), have been performed.