Furthermore, PD-1 blockade may promote the proliferation of myeloid-derived suppressor cells (MDSCs) (Strauss et al., 2020), which could regulate the immune response in chronic HBV- infected patients via PD-1 induced IL-10; and they may also promote the induction of Tregs and exhausted CD8+T cells and inhibit NK cells in HCC (Li et al., 2020). Here, PDCD1 is linked to hepatocellular carcinoma.