Tagraxofusp, a CD123-directed cytotoxin consisting of recombinant human interleukin-3 fused to a truncated diphtheria toxin, has been an integral agent for patients with both newly diagnosed and relapsed/refractory BPDCN since its Food and Drug Administration (FDA) approval in December 2018. Here, IL3 is linked to CD4+/CD56+ hematodermic neoplasm.