The HBV infection–related HCC immunosuppressed tumor microenvironment features upregulation of PD-1 in CD8+ T cells; long-lasting inhibition of Tregs via higher levels of IL-10 and TGF-β secretion; and the co-inhibitory signal of LAG3, TIM-3, and CTLA-4. Here, PDCD1 is linked to hepatocellular carcinoma.