Optimization of Aminoindazole derivatives as highly selective covalent inhibitors for wild-type and mutant FGFR4

Area of Science:

• Oncology
• Medicinal Chemistry
• Molecular Biology

Background:

• Fibroblast Growth Factor Receptor 4 (FGFR4) is implicated in hepatocellular carcinoma (HCC) pathogenesis via the FGFR4-FGF19 pathway.
• Existing FGFR4 inhibitors lack approval, and acquired resistance due to FGFR4 mutations presents a significant unmet clinical need.

Purpose of the Study:

• To design and synthesize novel 3-amido-1H-indazole-based irreversible inhibitors targeting wild-type (WT) and mutated FGFR4.
• To evaluate the efficacy of these inhibitors, particularly against resistant FGFR4 mutants relevant to cancer therapy.

Main Methods:

• Synthesis of a series of 3-amido-1H-indazole derivatives.
• In vitro kinase inhibition assays to determine IC50 values for WT and mutant FGFR4.
• Cell-based assays using Ba/F3 cell lines engineered with FGFR4 variants.
• Kinase selectivity profiling against a panel of 66 kinases.

Main Results:

• The representative compound, 48c, demonstrated potent inhibition of FGFR4^WT kinase (IC50 = 2.9 nM).
• Compound 48c exhibited picomolar activity against FGFR4^WT, FGFR4^V550L, and FGFR4^V550M-driven Ba/F3 cells (IC50 < 0.1-0.3 nM).
• 48c displayed high selectivity across a panel of 66 kinases with a cysteine at the hinge region.

Conclusions:

• 3-amido-1H-indazole-based irreversible inhibitors are effective against FGFR4, including clinically relevant mutants.
• Compound 48c shows significant potential as a therapeutic candidate for overcoming resistance in FGFR4-associated tumors like HCC.