A phase I clinical trial (NCT02159495) is examining the safety and efficacy of CD123 CAR T cell therapy using a lentivirally transduced second-generation CAR with CD28 co-stimulation (CD123CAR-CD28-CD3ζ-EGFRt) in adult patients with relapsed/refractory AML and persistent or recurrent BPDCN. Here, CD28 is linked to acute myeloid leukemia.