In difficult-to-treat leukemia subtypes, new targeted therapies against FMS-like tyrosine kinase 3 (FLT3) and isocitrate dehydrogenase 1 and 2 (IDH1/IDH2), as well as venetoclax for B-cell lymphoma 2 (BCL-2), also have brought about improved long-term survival in recent years (2–5). This evidence concerns the gene FLT3 and leukemia.