Narazaciclib, a novel multi-kinase inhibitor with potent activity against CSF1R, FLT3 and CDK6, shows strong anti-AML...

Area of Science:

• Oncology
• Pharmacology

Background:

• Colony-stimulating factor 1 receptor (CSF1R) is a receptor tyrosine kinase crucial for macrophage function and is overexpressed in some acute myeloid leukemia (AML) cases.
• Novel multi-kinase inhibitors offer potential therapeutic strategies for AML by targeting key signaling pathways.

Purpose of the Study:

• To evaluate the anti-AML effects of narazaciclib (HX301), a novel multi-kinase inhibitor with high potency against CSF1R.
• To investigate the efficacy of narazaciclib in preclinical AML models, particularly those with CSF1R overexpression or specific FLT3 mutations.

Main Methods:

• In vitro kinase assays to determine the potency of narazaciclib against CSF1R, FLT3, and CDK6.
• Cell proliferation assays using primary macrophages and AML cell lines with varying CSF1R or FLT3 mutational status.
• In vivo pharmacology studies using five AML xenograft models to assess tumor growth inhibition and systemic disease suppression.

Main Results:

• Narazaciclib exhibited high potency against CSF1R (IC50 ~0.285 nM), FLT3 (IC50 ~19.77 nM), and CDK6 (IC50 ~0.53 nM).
• In vitro, narazaciclib demonstrated significant growth inhibition in primary macrophages and a subset of AML cell lines.
• In vivo, narazaciclib suppressed tumor growth in FLT3-ITD AML xenografts and completely eradicated systemic growth in models with high CSF1R or FLT3-ITD, including resistant variants. Significant reductions in bone marrow leukemia burden were observed.

Conclusions:

• Narazaciclib shows significant anti-leukemic activity in preclinical AML models, particularly those driven by CSF1R or mutant FLT3-ITD.
• Its ability to suppress leukemia in the bone marrow suggests potential for more effective therapy compared to agents targeting only peripheral cells.
• Narazaciclib is a promising candidate for treating a subset of AML, especially those with CSF1R overexpression or FLT3-ITD mutations, including resistant cases.