Quizartinib is the most selective type II FLT3 inhibitor and has shown the strongest single-agent activity in patient population with R/R-AML (acute myeloid leukemia) with FLT3 mutations. The FLT3 tyrosine kinase inhibitors act as direct inhibitors of FLT3 via competitive inhibition of ATP-binding sites in the FLT3 receptor. Type II FLT3 inhibitors bind the FLT3 receptor in the inactive conformation in a region adjacent to the ATP-binding domain. As a result of this binding affinity, these inhibitors prevent activity of ITD (the internal tandem duplication) mutations but do not target TKD (the tyrosine kinase domain) mutations