PHI-101 is an orally active FLT3 inhibitor that overcomes resistance to multiple drug-resistant mutations. PHI-101 potently inhibits FLT3 single activating mutations (ITD or TKD mutants) and has inhibitory activity against FLT3 double (ITD/D835Y or ITD/F691L) and triple (ITD/D835Y/F691L) resistance mutations. PHI-101 has potential for research in relapsed or refractory acute myeloid leukemia (AML).