Biochemical Characterization of TAK-593, a Novel VEGFR/PDGFR Inhibitor with a Two-Step Slow Binding Mechanism

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• 作者：Hidehisa Iwata ; Shinichi Imamura ; Akira Hori ; Mark S. Hixon ; Hiroyuki Kimura ; Hiroshi Miki
• 刊名：Biochemistry
• 出版年：2011
• 出版时间：February 8, 2011
• 年：2011
• 卷：50
• 期：5
• 页码：738-751
• 全文大小：1197K
• 年卷期：v.50,no.5(February 8, 2011)
• ISSN：1520-4995

文摘

Inhibition of tumor angiogenesis leads to a lack of oxygen and nutrients in the tumor and therefore has become a standards of care for many solid tumor therapies. Dual inhibition of vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR) protein kinase activities is a popular strategy for targeting tumor angiogenesis. We discovered that TAK-593, a novel imidazo[1,2-b]pyridazine derivative, potently inhibits tyrosine kinases from the VEGFR and PDGFR families. TAK-593 was highly selective for these families, with an IC₅₀ >1 渭M when tested against more than 200 protein and lipid kinases. TAK-593 displayed competitive inhibition versus ATP. In addition, TAK-593 inhibited VEGFR2 and PDGFR尾 in a time-dependent manner, classifying it as a type II kinase inhibitor. Analysis of enzyme鈭抜nhibitor preincubation experiments revealed that the binding of TAK-593 to VEGFR2 and PDGFR尾 occurs via a two-step slow binding mechanism. Dissociation of TAK-593 from VEGFR2 was extremely slow (t_1/2 >17 h), and the affinity of TAK-593 at equilibrium (K_i*) was less than 25 pM. Ligand displacement analysis with a fluorescent tracer confirmed the slow dissociation of TAK-593. The dissociation rate constants were in good agreement between the activity and ligand displacement data, and both analyses supported slow dissociation of TAK-593. The long residence time of TAK-593 may achieve an extended pharmacodynamic effect on VEGFR2 and PDGFR尾 kinases in vivo that differs substantially from its observed pharmacokinetic profile.