Because overexpression of PD-L1 in tumor cells is related to the downregulation of effector T-cell function and represents a potent mechanism of tumor immune evasion [34], our findings imply a possible role for sPD-L1 in allowing tumor cells to escape from anti-tumor immunity, similar to the T-cell exhaustion through the immune checkpoint mechanism seen in the PD1/PD-L1 axis [35, 36]. This evidence concerns the gene SPDL1 and neoplasm.