In vitro activity: Derazantinib (formerly known as ARQ 087) is a novel, orally bioavailable, ATP competitive, small molecule, multi-kinase inhibitor with potent in vitro and in vivo activity against FGFR (fibroblast growth factor receptor) addicted cell lines and tumors with IC50s of 4.5, 1.8, and 4.5 nM for FGFR1-3 respectively in biochemical assay, IC50 values of 1.8 nM for FGFR2, and 4.5 nM for FGFR1 and 3. In cells, ARQ 087 exhibited inhibition of FGFR2 auto-phosphorylation and other proteins downstream in the FGFR pathway (FRS2α, AKT, ERK) as evidenced by the response to ARQ 087 treatment. Cell proliferation studies demonstrated ARQ 087 has anti-proliferative activity in cell lines driven by FGFR dysregulation, including amplifications, fusions, and mutations. Cell cycle studies in cell lines with high levels of FGFR2 protein showed a positive relationship between ARQ 087 induced G1 cell cycle arrest and subsequent induction of apoptosis. In addition, ARQ 087 was effective at inhibiting tumor growth in vivo in FGFR2 altered, SNU-16 and NCI-H716, xenograft tumor models with gene amplifications and fusions. ARQ 087 is currently being studied in a phase 1/2 clinical trial that includes a sub cohort for intrahepatic cholangiocarcinoma patients with confirmed FGFR2 gene fusions (NCT01752920).

Kinase Assay: Derazantinib is titrated in DMSO utilizing a 3-fold dilution scheme, and then diluted 10-fold further in deionized water for a final DMSO concentration of 10%. A volume (2.5 μL) of these dilutions or vehicle is added to each well of a reaction plate. FGFR1 or FGFR2 is added to assay buffer to each well in a volume of 17.5 μL for a final concentration of 0.50 or 0.25 nM, respectively. After a 30-minute pre-incubation period, ATP and substrate are added in assay buffer (5 μL) for final concentrations of 0-1,000 μM ATP and 80 nM biotinylated-PYK2, for a final reaction volume of 25 μL. The plates are incubated for 60 minutes at room temperature, and then stopped in the dark by the addition of 10 μL stop/detection mixture prepared in assay buffer containing EDTA

Cell Assay: Cells are seeded at 3000-5000 cells per well with 130 μL media in 96-well tissue culture treated plates. The cells are incubated overnight and subsequently treated with 3-fold serial dilutions of Derazantinib starting at 100 μM. The cells are returned to a 37°C humidified incubator for 72 hours. Cell proliferation is measured using MTS assay.