To broaden the success of CAR-T cell treatment for CML, Zhou et al. attempted to construct second-generation DPP4 targeting CAR-T cells utilizing 4-1BB (CD137) as costimulatory domain to target leukaemia stem cells [76,77]. The gene discussed is TNFRSF9; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.