The clinical importance of boosting miR-155 levels in CAR T cells goes beyond TGF-β resistance, as miR-155−/− CD8+ T cells in tumor tissues display reduced proliferation and invasion capabilities, which can be restored with immune checkpoint antibody treatment, indicating that miR-155 regulates pathways essential for tumor immune responses [165,167]. This evidence concerns the gene TGFB1 and neoplasm.