CD274 and hepatocellular carcinoma: Recently, Teng et al. showed that HCC patients infected with HBV, with either the presence of deletions spanning the pre-S2 gene segment or a high percentage of pre-S2 plus pre-S1 + pre-S2 gene deletions, displayed higher numbers and activity levels of regulatory T cells (Tregs) and higher expression levels of immune checkpoint programmed death ligand 1 (PD-L1) in tumor tissues than patients without HBV deletion mutants [38,39].