Structural Optimization and MD Simulation Study of Benzimidazole Derivatives as Potent Mutant FLT3 Kinase Inhibitors...

Area of Science:

• Medicinal Chemistry
• Hematology
• Molecular Biology

Background:

• Acute myeloid leukemia (AML) is an aggressive cancer with poor outcomes, often driven by FMS-like tyrosine kinase 3 (FLT3) mutations.
• FLT3 mutations confer resistance to existing therapies, highlighting the need for novel treatment strategies.
• Previous work identified a benzimidazole-based inhibitor, 4ACP, with activity against FLT3 mutants.

Purpose of the Study:

• To synthesize and evaluate novel benzimidazole derivatives as potent inhibitors of FLT3 mutants.
• To identify a lead compound with enhanced activity and selectivity for targeting resistant AML.

Main Methods:

• Synthesized 31 benzimidazole derivatives by modifying the 4-acetamidophenyl group and N1-phenyl/C2 substituents.
• Assessed inhibitory activity against FLT3-ITD and FLT3-TKD mutants, including D835Y.
• Evaluated antiproliferative effects on AML cell lines and assessed selectivity against other kinases like KIT.
• Conducted molecular dynamics studies to understand structure-activity relationships.

Main Results:

• Compound 21l showed potent inhibition of FLT3-TKD(D835Y) (IC50 = 1.47 nM).
• Derivative 22b, linked to a solvent-accessible group, exhibited sub-nanomolar activity (IC50 = 0.48 nM) against FLT3-TKD(D835Y).
• Compound 22b demonstrated preferential antiproliferative activity against FLT3-mutated AML cell lines and significant selectivity over KIT (80-fold).
• 22b induced cell-cycle arrest and apoptosis at low nanomolar concentrations, with dose-dependent inhibition of FLT3 signaling pathways.

Conclusions:

• Compound 22b is a highly potent and selective inhibitor of mutant FLT3, particularly FLT3-TKD(D835Y).
• The findings establish 22b as a promising candidate for further development against resistant AML.
• The selectivity profile suggests a potentially favorable safety margin with reduced myelosuppression.