This is an escalation/expansion, open label, multicenter study to investigate the safety and the RP2D of the combination of iadademstat with gilteritinib in FLT3-mutated R/R AML. All patients will enter a screening period up to 14 days prior to the start of treatment. Patients will be administered treatment over 28-day cycles consisting of iadademstat PO at specific dose levels, 5d ON- 2d OFF every week, with standard of care gilteritinib (120 mg PO daily). Iadademstat initial dose will be 100 μg (Table 1). Participants may remain on treatment until they reach discontinuation criteria. The study will start with an escalation phase to determine the pharmacologically-active dose (i.e., the minimum safe and biologically active dose) of the combination in patients with FLT3-mutated R/R AML.