It has been well established that exosomes suppress or potentiate tumor progression via various molecules with different underlying mechanisms, one of which is that exosomal PD-L1 promotes tumor progression through direct interaction with PD-1 on the surface of lymphocytes as efficiently as PD-L1 on the tumor cell surface via impairing CTL, enhancing memory immune [37, 38]. This evidence concerns the gene PDCD1 and neoplasm.