Tumors limit the host immune response via upregulation of PD-1 ligand (PD-L1) and its ligation to PD-1 on antigen-specific CD8+ T cells, which suggests the expression of PD-L1 in tumor tissues is closely related to the efficacy of PD-L1 blockade (Tumeh et al., 2014). Here, CD8A is linked to neoplasm.