FLT3 and acute promyelocytic leukemia: Scientific understanding of the AML biology has led to the development of targeted treatment approaches [4], i.e., the all-trans retinoic acid (ATRA) treatment for acute promyelocytic leukemia (APL) that carries the PML-RARα translocation [18] or the use of FLT3 kinase inhibitors in FLT3-mutated cases [19,20].