IDO1 and cancer: Immunomodulatory factors are other anti-cancer agents that can be applied in combination with CAR-T cells, including GSIS as an inhibitor of GS, mir-155 as an IDO inhibitor, Lenidomide as an enhancer of inflammatory cytokines and inhibitor of anti-inflammatory cytokines as well as other factors such as decitabine, SMACs, HDACi, etc. Consequently, the synergistic effects of different treatments in their combined use can be more successful in degrading tumor cells and helping to regress the disease compared to monotherapy approaches.