The FMS-like tyrosine kinase 3 (FLT3) also known as cluster of differentiation antigen 135 (CD135) or fetal liver kinase-2 (Flk2) is a class III receptor tyrosine kinase (RTK) that plays a key role in controlling survival, proliferation, and differentiation of hematopoietic cells and it widely expresses in acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Mutations in FLT3 (both internal tandem duplications (ITD) and point mutations) are among the most common somatic mutations in AML patients and are associated with poor prognosis and outcome in those patients.