Novel Platform to achieve high avidity of heterodimers for targeted cancer imaging

 描述（由申请人提供）：分子靶向癌症成像对于癌症患者护理的根本改善至关重要，图像质量和诊断准确性严重依赖于靶向受体和靶向配体（小分子、肽和抗体）之间的亲和力/特异性。同时将两个连接的配体与两个不同的靶向受体结合的异二聚体配体提供了一种广泛适用的方法，将低亲和力配体（Kd亲和力~ mM - μM）转化为具有高亲合力/特异性的配体（Kd亲和力~ nM）。这种高亲合力异二聚体通常通过以下方式来实现：1）合成许多具有不同接头的异二聚体;和2）单独测量它们的体外亲合力。然而，一旦感兴趣的受体发生变化，就需要重复整个过程（包括新的异二聚体文库合成和亲合力测量）以进行接头优化。甚至更令人失望的是，即使通过谨慎地选择其中有效的异二聚体可以应用于各种肿瘤的双受体对，在使用其中受体距离显著变化的特定细胞系的特定实验室中，异二聚体文库合成和亲合力测量需要再次进行。因此，缺乏通用和快速的接头优化平台已被认为是广泛和常规利用异二聚体配体进行临床前和/或临床研究的主要障碍之一。为了克服这个问题，利用两个生物正交连接，我们提出了第一个，高通量，体外筛选平台，易于制备高亲和力异二聚体，它可以广泛应用于各种双受体组合和不同的肿瘤。这种广泛应用的技术将显着加速和/或增强使用异二聚体的受体靶向癌症成像，特别是在以下情况下：1）当靶向受体以低丰度表达时;和2）没有高亲和力（和/或特异性）的情况单价配体可用。

 DESCRIPTION (provided by applicant): Molecularly targeted cancer imaging is critical for fundamental improvements in cancer patient care, and image quality and diagnostic accuracy rely heavily on the affinity/specificity between the targeted receptor and targeting ligand (small molecules, peptides and antibodies). A heterodimeric ligand that simultaneously associates two linked ligands with two different targeting receptors provides a broadly applicable approach to convert low affinity ligands (Kdaffinity ~ mM - µM) to the one with high avidity/specificity (Kdavidity ~ nM). Such high avidity heterodimers are usually pursued by: 1) synthesizing a number of heterodimers with different linkers; and 2) measuring their in vitro avidities individually. However, once the receptor of interest changes, repeating the entire procedure (including new heterodimer library synthesis and avidity measurement) is required for linker optimization. Even more disappointing is the fact that even by prudently selecting dual-receptor pairs where a potent heterodimer may be applied to a variety of tumors, in a particular lab using particular cell lines(s) where receptor distance(s) varied significantly, heterodimer library synthesis and avidity measurements needs to be conducted again. Therefore, the lack of a generic and rapid linker optimization platform has been considered as one of the major barriers for the widespread and routine utilization of heterodimeric ligand for preclinical and/or clinical studies. In order to overcome this problem, utilizing two bioorthogonal ligations, we propose the first, high-throughput, in vitro screening platform for easy preparation of high avidity heterodimers, which can be broadly applied to various dual-receptor combinations and different tumors. Such widespread applicable technology will significantly accelerate and/or enhance receptor-targeted cancer imaging using heterodimers, particularly in the following situations: 1) when targeted receptor(s) are expressed in low abundance; and 2) situations where no high affinity (and/or specificity) monovalent ligands are available.