TGFB1 and neoplasm: Hence, the main mechanisms involved in the disease relapse after CAR-T therapy include downregulation of target antigen in response to therapy, inadequate T cell potency, intratumoral heterogeneity, incomplete antigen coverage, upregulation of suppressive ligands (Fas, PD-L1, and other checkpoint molecules), downregulation of anti-inflammatory cytokines (IL-10 and TGF-β), an immunosuppressive tumor microenvironment, and secondary effects of palliative treatment with corticosteroids [809,810,811,812].