Discovery of FYJ-195 as a Highly Potent FLT3 Inhibitor against Multiple Acquired Resistance Mutations in Acute Myeloid Leukemia

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Abstract
The efficacy of FLT3 inhibitors in acute myeloid leukemia (AML) is severely limited by resistance mutations, particularly the recalcitrant gatekeeper F691L and activation loop D835V/Y variants. Herein, through the structure-guided optimization of our previously reported lead SILA-123, we identified FYJ-195, a highly potent type II FLT3 inhibitor capable of overcoming these recalcitrant mutants. FYJ-195 exhibited single-digit nanomolar potency against Ba/F3-FLT3-ITD-F691L (IC50 = 9.09 nM) and subnanomolar activity against Ba/F3-FLT3-ITD-D835Y (IC50 = 4.64 nM) and Ba/F3-FLT3-ITD-D835V (IC50 = 0.76 nM). In vivo, FYJ-195 induced profound tumor regression (TGI = 125%) in the MV4-11 xenograft model (10 mg/kg) and achieved robust tumor growth suppression (TGI = 68.6%) in the Ba/F3-FLT3-ITD-F691L model (50 mg/kg), where quizartinib was ineffective. Mechanistic studies confirmed that FYJ-195 effectively blocked FLT3 signaling and induced apoptosis without observable toxicity. Collectively, FYJ-195 represents a promising lead candidate for drug-resistant AML.
Funding Information
  • National Key Research and Development Program of China (2020YFA0509404)
  • National Natural Science Foundation of China (82373710)
  • National Natural Science Foundation of China (82504578)
  • National Natural Science Foundation of China (82574235)
  • Priority Academic Program Development of Jiangsu Higher Education Institutions
  • Natural Science Foundation of Jiangsu Provincial Colleges and Universities (21KJB350005)

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