These CAR T cells could eradicate tumors that were 100% antigen-positive; however, the mesoCAR T cells were unable to cure tumors even when only 10% of tumor cells were mesothelin-negative, even with the co-administration of (1) immune modulatory agents such as anti-PD-1, anti-CTLA-4 or anti-TGF-β (transforming growth factor β) antibodies; (2) agonistic CD40 antibodies; or (3) an IDO (indoleamine 2,3-dioxygenase) [89]. Here, IDO1 is linked to neoplasm.