Motesanib Diphosphate (AMG-706)

Motesanib Diphosphate has broad activity against the human VEGFR family, and displays >1000 selectivity against EGFR, Src, and p38 kinase. Motesanib Diphosphate significantly inhibits VEGF-induced cellular proliferation of HUVECs with an IC50 of 10 nM, while displaying little effect at bFGF-induced proliferation with an IC50 of >3,000 nM. Motesanib Diphosphate also potently inhibits PDGF-induced proliferation and SCF-induced c-kit phosphorylation with IC50 of 207 nM and 37 nM, respectively, but not effective against the EGF-induced EGFR phosphorylation and cell viability of A431 cells. ^[1] Althouth displaying little antiproliferative activity on cell growth of HUVECs alone, Motesanib Diphosphate treatment significantly sensitizes the cells to fractionated radiation. ^[2]

Administration of Motesanib Diphosphate at 100 mg/kg significantly inhibits VEGF-induced vascular permeability in a time-dependent manner. Oral administration of Motesanib Diphosphate twice daily or once daily potently inhibits, in a dose-dependent manner, VEGF-induced angiogenesis using the rat corneal model with ED50 of 2.1 mg/kg and 4.9 mg/kg, respectively. Motesanib Diphosphate induces a dose-dependent tumor regression of established A431 xenografts by selectively targeting neovascularization in tumor cells. ^[1] Administration of Motesanib Diphosphate in combination with radiation displays significant anti-tumor activity in head and neck squamous cell carcinoma (HNSCC) xenograft models. ^[2] Motesanib Diphosphate treatment also induces significant dose-dependent reductions in tumor growth and blood vessel density of MCF-7, MDA-MB-231, or Cal-51 xenografts. ^[3]

• In vitro kinase assays

  Optimal enzyme, ATP, and substrate (gastrin peptide) concentrations are established for each enzyme using homogeneous time-resolved fluorescence (HTRF) assays. Motesanib Diphosphate is tested in a 10-point dose-response curve for each enzyme using an ATP concentration of two-thirds K_m for each. Most assays consist of enzyme mixed with kinase reaction buffer [20 mM Tris-HCl (pH 7.5), 10 mM MgCl₂, 5 mM MnCl₂, 100 mM NaCl, 1.5 mM EGTA]. A final concentration of 1 mM DTT, 0.2 mM NaVO₄, and 20 μg/mL BSA is added before each assay. For all assays, 5.75 mg/mL streptavidin-allophycocyanin and 0.1125 nM Eu-PT66 are added immediately before the HTRF reaction. Plates are incubated for 30 minutes at room temperature and read on a Discovery instrument. IC50 values are calculated using the Levenberg-Marquardt algorithm into a four-parameter logistic equation.

• Cell lines

  A431, MO7e, HUVEC and NHDF cells

• Concentrations

  Dissolved in DMSO, final concentrations ~25 μM

• Incubation Time

  2 hours

• Method

  Cells are preincubated for 2 hours with different concentrations of Motesanib Diphosphate, and exposed with 50 ng/mL VEGF or 20 ng/mL bFGF for an additional 72 hours. Cells are washed twice with DPBS, and plates are frozen at -70 °C for 24 hours. Proliferation is assessed by the addition of CyQuant dye, and plates are read on a Victor 1420 workstation. IC50 data are calculated using the Levenberg-Marquardt algorithm into a four-parameter logistic equatio

• Animal Models

  Female Sprague-Dawley rats with induced corneal angiogenesis, and female CD-1 nu/nu mice injected s.c. with A431 cells

• Dosages

  ~100 mg/kg

• Administration

  Orally administered twice daily or once daily