IL3 and CD4+/CD56+ hematodermic neoplasm: Another CD123-targeting biotherapeutic agent associated with severe neutropenia is the human IL3 fusion toxin Tagraxofusb (SL-401) [53,54], which was approved by the FDA in 2018 for treatment of blastic plasmacytoid dendritic cell neoplasm (BPDCN), being found to be not very active in AML at the MTD of 12.5 mcg/kg/day (Clinicaltrial.gov identifier: NCT02270463).