PDCD1 and hepatocellular carcinoma: Exhausted HBV-specific CD8+ T cells characterized by the expression of immune-suppressive receptors, including the programmed cell death protein-1 (PD-1), cytotoxic T-lymphocyte antigen 4 (CTLA4), T cell immunoglobulin and mucin domain 3 (TIM-3) and T cell immunoglobulin and ITIM domain (78), which was correlated with development and poor prognosis of HBV-related HCC (79).