Copyright © 2018 Clarivate Analytics Tagraxofusp is a novel therapeutic agent in clinical trials for acute myeloid leukemia (AML), myelodysplastic syndrome (MDS) and blastic plasmacytoid dendritic cell neoplasm (BPDCN). As a fusion protein of diphtheria toxin and interleukin-3 (IL-3), it targets cells expressing the IL-3 receptor (IL-3R) and leads to cell death. AML, MDS and BPDCN all have leukemic cells and cancer stem cells expressing high levels of IL-3R making tagraxofusp an ideal therapeutic approach to target tumor cells. Preclinical and clinical studies have demonstrated minimal toxicity, selectivity of the drug for tumor cells and promising clinical benefit from this agent. In this review, we will highlight the preclinical pharmacology and efficacy and discuss the results of clinical trials examining tagraxofusp treatment to date.