Synthesis of Novel c(AmpRGD)–Sunitinib Dual Conjugates as Molecular Tools Targeting the αvβ3 Integrin/VEGFR2 Couple and Impairing Tumor-Associated Angiogenesis

On the basis of a previously discovered anti-αVβ3 integrin peptidomimetic (c­(AmpRGD)) and the clinically approved antiangiogenic kinase inhibitor sunitinib, three novel dual conjugates were synthesized (compounds 1–3), featuring the covalent and robust linkage between these two active modules. In all conjugates, the ligand binding competence toward αVβ3 (using both isolated receptors and αVβ3-overexpressing endothelial progenitor EP cells) and the kinase inhibitory activity (toward both isolated kinases and EPCs) remained almost untouched and comparable to the activity of the single active units. Compounds 1–3 showed interesting antiangiogenesis properties in an in vitro tubulogenic assay; furthermore, dimeric-RGD conjugate 3 strongly inhibited in vivo angiogenesis in Matrigel plug assays in FVB mice. These results offer proof-of-concept of how the covalent conjugation of two angiogenesis-related small modules may result in novel and stable molecules, which impair tumor-related angiogenesis with equal or even superior ability as compared to the single modules or their simple combinations.本研究基于此前发现的抗αVβ3整合素（αVβ3 integrin）肽模拟物c(AmpRGD)与临床获批的抗血管生成激酶抑制剂舒尼替尼（sunitinib），合成了3种新型双模块偶联物（化合物1~3），其特征为两个活性模块间通过共价键实现牢固连接。在所有偶联物中，针对αVβ3的配体结合能力（分别采用分离纯化的受体与过表达αVβ3的内皮祖细胞（endothelial progenitor cells，简称EP细胞、EPCs）进行检测）以及激酶抑制活性（分别针对分离的激酶与EPCs进行检测）基本保持不变，且与单一活性单元的活性相当。化合物1~3在体外管形成实验中展现出良好的抗血管生成活性；进一步研究表明，二聚体RGD偶联物3可在FVB品系小鼠的基质胶栓实验中强效抑制体内血管生成。本研究结果为两种血管生成相关小分子模块的共价偶联可获得新型稳定分子提供了概念验证，这类分子对肿瘤相关血管生成的抑制能力与单一模块相当，甚至优于单一模块或其简单混合物。