TIGIT and hepatocellular carcinoma: Studies in our lab have also illustrated that breakdown of adaptive immune tolerance by blockade of TIGIT (T cell immunoglobulin and ITIM domains, a checkpoint receptor involved in mediating T cell exhaustion in tumors) combined with HBsAg vaccination is able to recover the anti-HBV function of autologous HBsAg-specific CTLs including IFN-γ and TNF-α prodction, which was responsible for mediating HCC progression in HBs-Tg mice (37).