For the treatment of AML and CD19 therapy-resistant B-ALL, CD123 emerged as a suitable target due to its overexpression in AML and B-ALL blasts.18, 19, 20, 21 However, in contrast to CD19, CD123 is a challenging target, as it is also expressed on hematopoietic progenitors4,22, 23, 24 and endothelia.25 The gene discussed is CD19; the disease is acute lymphoblastic leukemia.