Considering interaction between PD-L1 including exoPD-L1 and PD-1 receptor on PD-1+CD8+ T cells might result in dysfunction and exhaustion of the T cells and enhanced TGF-β signaling in tumor microenvironment, higher level of PD-1+CD8+ T cells in high exoPD-L1 group might also indicate immunosuppressive status of the disease39. Here, CD8A is linked to neoplasm.