FLT3-IN-21 (compound LC-3) is a potent FLT3 inhibitor ( IC 50 : 8.4 nM) and induces apoptosis. FLT3-IN-21 can arrest the cell cycle in the G1 phase and inhibit the proliferation of FLT3-ITD-positive AML cells MV-4-11 ( IC 50 : 5.3 nM). In mice, FLT3-IN-21 (10 mg/kg/d) inhibited tumor growth in the MV-4-11 xenograft model (TGI=92.16%).