ASP5878 potently inhibited the tyrosine kinase activities of recombinant FGFR1, 2, 3, and 4 with IC50 values of 0.47, 0.60, 0.74, and 3.5 nmol/L.

FGFR4:3.5nM, FGFR3:0.74nM, FGFR2:0.6nM, FGFR1:0.47nM

sorafenib administration for 14 days caused 40% tumor growth inhibition in the Hep3B2.1-7 xenograft model. Even after continuous sorafenib treatment, the Hep3B2.1-7 tumor gradually enlarged, and 47% tumor growth inhibition was observed by day 31. In contrast, the switch from sorafenib to ASP5878 on day 14 induced 83% tumor regression on day 52 relative to the tumor size observed on day 14. This indicates the therapeutic potential of ASP5878 for FGF19-overexpressing HCC patients who previously received sorafenib treatment.

Inhibitory activities of 128 serine/threonine kinases were measured using the Mobility Shift Assay Kit.?IC50 values were determined for kinases that were inhibited by more than 50% by 200 nmol/L of ASP5878.

The human HCC cell lines,?The experiments were conducted using low-passage cultures of these stocks.?The cells were seeded in 96-well plates and incubated overnight.?The cells were treated with ASP5878 for 5 days.?Cell viability was measured using CellTiter-Glo.

HuH-7-Luc cells were inoculated into hepatic parenchyma at 3×10^5 cells/0.01 mL (Matrigel 100%)/mouse.?One week after inoculation, the mice were divided into three groups (n = 5 per group) on day 0 on the basis of bioluminescent imaging.?Vehicle (Cremophor EL/ethanol or 0.5% MC), sorafenib (30 mg/kg), or ASP5878 (3 mg/kg) was administered as a once-daily oral dose for 91 days.?Tumor growth was monitored by in vivo bioluminescent imaging of the abdomen after intraperitoneally injecting luciferin using IVIS-Lumina2.?During the study period (181 days), the survival of mice bearing hepatic tumors was recorded.?The condition of the mice was monitored daily.?The mice were scored as dead if any of the following signs of suffering were observed: cachexia, weakening, and difficulty in moving or eating.?Mice that were scored as dead were euthanized.