TGFB1 and neoplasm: Assuming that the TGF-β content in the EVs is related to its levels in the tumor, the main hypothesis to explain the association between high EV TGF-β mRNA levels and clinical response is that tumors overproducing TGF-β induce T-cell exhaustion that leads to decreased T-cell proliferation and function which may be successfully restored by the administration of anti-PD-1 antibodies.