FGF401, a first-in-class highly selective and potent FGFR4 inhibitor for the treatment of FGF19-driven hepatocellular cancer

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver and it is the third leading cause of cancer-related deaths worldwide. Recently, aberrant signaling through the fibroblast growth factor 19 (FGF19) / fibroblast growth factor receptor 4 (FGFR4) axis has been implicated in HCC. Here, we describe the development of FGF401, a highly potent and selective, first in class, reversible-covalent small-molecule inhibitor of the kinase activity of FGFR4. FGF401 is exquisitely selective for FGFR4 versus the other FGFR paralogues FGFR1, FGFR2, FGFR3 and all other kinases in the kinome. FGF401 has excellent drug-like properties showing a robust pharmacokinetic / pharmacodynamics / efficacy relationship, driven by a fraction of time above the phospho-FGFR4 IC90 value. FGF401 has remarkable anti-tumor activity in mice bearing HCC tumor xenografts and patient-derived xenograft models that are positive for FGF19, FGFR4 and KLB. FGF401 is the first FGFR4 inhibitor to enter clinical trials, and a PhI/II study is currently ongoing in HCC and other solid malignancies.