LY2874455

LY2874455 is a pan-FGFR inhibitor with IC₅₀s of 2.8, 2.6, 6.4, 6 nM for FGFR1, FGFR2, FGFR3, FGFR4, respectively. IC50 & Target:IC50: 2.8 nM (FGFR1), 2.6 nM (FGFR2), 6.4 nM(FGFR3), 6 nM (FGFR4)^[1] In Vitro: LY2874455 potently inhibits the Erk phosphorylation induced by FGF2 and FGF9 in both cell lines in a dose-dependent manner, with average IC₅₀ values of 0.3 to 0.8 nM. LY2874455 indeed inhibits FGFR2 phosphorylation in SNU-16 and KATO-III cells, with estimated IC₅₀ values of 0.8 and 1.5 nM, respectively. In addition, LY2874455 inhibits the phosphorylation of FRS2, an immediate downstream target of FGFR in these cell lines, again with a similar potency of 0.8 to 1.5 nM. Together, these results suggest that LY2874455 inhibits FGFR in the cell. The relative IC₅₀ values of LY2874455 for KMS-11, OPM-2, L-363, and U266 cells are determined to be 0.57, 1.0, 60.4, and 290.7 nM, respectively^[1]. In Vivo: LY2874455 exhibits a rapid, robust, dose-dependent inhibition of tumor growth in all 4 models tested. Importantly, this molecule causes a significant regression of tumor growth in the RT-112, SNU-16, and OPM-2 tumor models, especially when dosed at 3 mg/kg twice a day. Also, LY2874455 exhibits an excellent pharmacokinetic/pharmacodynamic relationship as shown by its dose-dependent inhibition of the tumor growth at TED₅₀ and TED₉₀ (1 and 3 mg/kg, respectively). When tested in the RT-112 tumor xenograft model on an intermittent dosing schedule (twice a day 1 week on and 1 week off or twice a day 2 days on and 2 days off), LY2874455 is also efficacious. When rats are dosed with LY2874455 at 1 and 3 mg/kg, which is 2.6- and 7.7-fold over the TED₅₀ (0.39 mg/kg) obtained in the rat heart IVTI assay, respectively, there are no significant changes observed in blood pressure. However, when rats are dosed with LY2874455 at 10 mg/kg, which is 25.6-fold over the TED₅₀, there are significant increases observed in arterial pressures^[1].