Design, synthesis, and Lead optimization of novel Quinazoline-based FLT3 inhibitors with potent anti-acute myelogenous leukemia activity.

FLT3 mutations, including internal tandem duplications (ITD) and tyrosine kinase domain (TKD) variants, are key drivers of acute myeloid leukemia (AML) and represent attractive therapeutic targets. Guided by a scaffold-hopping strategy based on G-749 (denfivontinib), a series of quinazoline-based derivatives was designed and synthesized to explore structure-activity relationships (SAR). Among them, compound W4 showed the most promising profile, exhibiting potent antiproliferative activity against MV4-11 and MOLM-13 cells and strong inhibition of FLT3-ITD (IC50 = 16.0 nM) and FLT3-D835Y (IC50 = 20.4 nM), while displaying negligible activity toward c-KIT kinase (IC50 > 100 μM). Mechanism studies indicated that W4 induced G0/G1 cell cycle arrest and apoptosis, accompanied by a reduction in intracellular reactive oxygen species levels and a loss of mitochondrial membrane potential. Collectively, these results identified W4 as a potent FLT3 inhibitor and provided valuable SAR insights for further scaffold optimization.