Motesanib (AMG 706) is an orally bioavailable receptor tyrosine kinase inhibitor with potential antineoplastic activity. AMG 706 selectively targets and inhibits vascular endothelial growth factor (VEGFR), platelet-derived growth factor (PDGFR), Kit, and Ret receptors, thereby inhibiting angiogenesis and cellular proliferation.

VEGFR1:2 nM, c-Kit:8 nM, VEGFR2:3 nM, VEGFR3:6 nM

Motesanib对人VEGFR家族具有广泛活性，对EGFR、Src和p38激酶的选择性>1000倍。Motesanib显著抑制VEGF诱导的HUVECs细胞增殖，IC50为10 nM，而对bFGF诱导的细胞增殖影响较小，IC50 > 3000 nM。此外，Motesanib强效抑制PDGF诱导的细胞增殖和SCF诱导的c-kit磷酸化，IC50分别为207 nM和37 nM，但对EGF诱导的EGFR磷酸化和A431细胞的细胞活力无效[1]。尽管对HUVECs细胞生长的抗增殖活性较小，Motesanib处理显著增强了细胞对分段放射线的敏感性[2]。

Motesanib (100 mg/kg) 显著抑制了 VEGF 引起的血管通透性，呈时间依赖性。通过口服 Motesanib 每天两次或一次的方式，以剂量依赖性强效抑制 VEGF 引发的血管生成，使用大鼠角膜模型，ED50 分别为 2.1 mg/kg 和 4.9 mg/kg。Motesanib 引起剂量依赖的 A431 异种移植瘤退缩，通过选择性针对肿瘤细胞中的新生血管化。Motesanib 结合放射治疗在头颈部鳞状细胞癌 (HNSCC) 异种移植模型中显示出显著的抗肿瘤活性[2]。此外，Motesanib 治疗在 MCF-7, MDA-MB-231 或 Cal-51 异种移植瘤中引起显著的剂量依赖性肿瘤生长和血管密度减少，与多西他赛或他莫昔芬联合时效果可显著增强[3]。

Optimal enzyme, ATP, and substrate (gastrin peptide) concentrations are established for each enzyme using homogeneous time-resolved fluorescence (HTRF) assays. Motesanib is tested in a 10-point dose-response curve for each enzyme using an ATP concentration of two-thirds Km?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.

Cells are preincubated for 2 hours with different concentrations of Motesanib, 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.