FLT3 and acute myeloid leukemia: Quizartinib is a second-generation FLT3 inhibitor and selectively inhibits class III receptor tyrosine kinases including FLT3, stem cell factor receptor (SCFR), colony-stimulating factor 1 receptor (CSF1R) and platelet derived growth factor receptors (PDGFRs), thus usually results in a better complete remissions in relapsed/refractory (r/r) AML [21].