Fexagratinib

Fexagratinib (ADSK091) is a potent inhibitor of the FGFR family with IC₅₀s of 0.2 nM, 2.5 nM, 1.8 nM, and 165 nM for FGFR1, FGFR2, FGFR3, and FGFR4, respectively. IC50 & Target:IC50: 0.2 nM (FGFR1), 2.5 nM (FGFR2), 1.8 nM (FGFR3), 165 nM (FGFR4)^[1] In Vitro: Fexagratinib also inhibits recombinant VEGFR2 (KDR) kinase activity with an IC₅₀ of 24 nM. In KG1a, Sum52-PE, MCF7, and KMS11 cell lines, Fexagratinib potently inhibits autophosphorylation of FGFR1, 2, and 3 tyrosine kinases (IC₅₀ values of 12, 2, and 40 nM, respectively) and displays weaker inhibition of FGFR4 cellular kinase activity (IC₅₀=142 nM). Significantly weaker inhibitory activity is observed versus cellular KDR and IGFR ligand-induced phosphorylation (IC₅₀ values of 258 and 828 nM, respectively), representing approximately 20- and 70-fold selectivity over cellular FGFR1. Besides, Fexagratinib potently inhibits FGFR phosphorylation and downstream signaling affected through FRS2, PLCγ, and MAPK at the cellular level^[1]. In Vivo: Female SCID mice bearing KMS11 tumors are randomized and treated chronically with Fexagratinib at a range of well-tolerated doses. Oral Fexagratinib treatment results in dose-dependent tumor growth inhibition. Twice daily administration of Fexagratinib at 3 mg/kg gives statistically significant tumor growth inhibition of 53% (P<0.0005 by one-tailed t test) when compare with vehicle-treated controls, whereas doses of 12.5 mg/kg once daily and 6.25 mg/kg twice daily results in complete tumor stasis (P<0.0001). A further efficacy study in the KG1a model with 12.5 mg/kg once daily Fexagratinib results in 65% tumor growth inhibition (P=0.002)^[1].