Design, synthesis, and biological evaluation of a series of indolone derivatives as novel FLT3 inhibitors for the treatment of acute myeloid leukemia

FLT3-ITD mutant has been extensively studied as a drug discovery target for acute myeloid leukemia. Based on our previous discovered FLT3 Inhibitor (2), a series of urea group based indolone derivatives were designed, synthesized, and biological evaluated as novel FLT3 inhibitors for the treatment of FLT3-ITD positive AML. Among them, compound LC-3 exhibited potent inhibitory effects against FLT3 (IC₅₀ = 8.4 nM) and significantly inhibited the proliferation of FLT3-ITD positive AML cells MV-4-11 (IC₅₀ = 5.3 nM). In the cellular context, LC-3 strongly inhibited FLT3-mediated signaling pathways and induced cellular Apoptosis by arresting cell cycle in G1 phase. In the in vivo studies, LC-3 significantly suppressed the tumor growth on MV-4-11 xenograft models (10 mg/kg/day, TGI = 92.16%) without exhibiting obvious toxicity. These results suggested that compound LC-3 might be a potential drug candidate for FLT3-ITD positive AML.