We observed that patients with many hematologic cancers expressed high levels of DKK1 and generated novel human DKK1-A2 CAR-T cells that can kill cancer cells from HLA-A2+ patients with myeloma, lymphoma, or leukemia. We also found that Th9-polarized T cells have enhanced antitumor effects in vivo. In this proposal, we will determine 1) whether and how Th9-polarized DKK1-A2 CAR-T cells are promising effector T cells for immunotherapy of human patients, and 2) whether Th9-polarized DKK1-A2 CAR-T cells are associated with reduced on- and off-target toxicities.