HEC73543 Versus Salvage Chemotherapy in R/R FLT3-ITD AML

Inclusion Criteria: * Subject is ≥ 18 years of age at the time of obtaining informed consent. * Subject has a diagnosis of primary acute myeloid leukemia (AML) or AML secondary to myelodysplastic syndrome (MDS) according to WHO classification; * Subject is refractory to or relapsed after first-line AML therapy (with or without hematopoietic stem cell transplant ) * Subject is positive for FLT3 mutation in bone marrow or whole blood as determined by the central lab * Subject has an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 * Subject is eligible for pre-selected salvage chemotherapy at the investigator's discretion Exclusion Criteria: * Subject has received prior treatment with other FLT3 inhibitors * Subject has AML that has relapsed after or is refractory to more than 1 line of therapy * Subject has an active uncontrolled infection * Subject is known to have human immunodeficiency virus infection * Subject has any condition which, in the investigator's opinion, makes the subject unsuitable for study participation