 The purpose of this study is to determine the clinical benefit of ASP2215 therapy in patients with FMS-like tyrosine kinase FLT3 mutated acute myeloid leukemia AML who are refractory to or have relapsed after first-line AML therapy as shown with overall survival OS compared to salvage chemotherapy, and to determine the efficacy of ASP2215 therapy as assessed by the rate of complete remission and complete remission with partial hematological recovery CRCRh in these patients. 