Harnessing transthyretin to extend the in vivo half-life of therapeutic peptides

描述(申请人提供)：利用转甲状腺素延长体内治疗性多肽的半衰期项目摘要：多肽的巨大治疗潜力尚未实现，到目前为止，失败的潜在多肽疗法远远多于成功的多肽疗法。阻碍多肽作为治疗药物更广泛使用的一个主要挑战是它们的药代动力学(PK)谱不佳，这是由于血清蛋白水解酶失活和肾脏快速消除导致的体内半衰期较短。因此，延长多肽在体内的半衰期显然是可取的，以便实现其治疗潜力，而不需要高剂量和/或频繁给药。多肽与大分子(如聚乙二醇或血清蛋白)的共价偶联已成为提高多肽在体内半衰期的主要途径。然而，这些大分子的空间位阻往往会损害多肽与其细胞外受体的结合，从而损害多肽的药效学(PD)性质。这项提议的总体目标是开发一种全新的方法，在不影响其生物活性的情况下，提高多肽在体内的半衰期。这一建议的主要假设是测试多肽与选择性转甲状腺激素(TTR，一种血清蛋白)配体的偶联是否允许这些多肽偶联可逆地与血清中的TTR结合。这将导致多肽在体内的半衰期增加，但最重要的是，将保持多肽与其受体的结合亲和力。一个主要的重点将是我们最近发现的迄今为止最有效和最有选择性的可逆TTR配体，AG10。我们已经在合成第一个AG10-肽结合物(Conj1；以GnRH为模型肽)方面取得了重大进展，我们对Conj1的体外初步结果与这一假设一致。在这项提案中，w将在体内评估conj1，并研究与Ttr的最佳连接系统和亲和力，从而 在这些AG10-GnRH结合物中提供PK和Pd之间的最佳平衡。将积极追求三个特定目标：目标1，设计和合成一系列AG10-GnRH结合物，并确定(在AG10和GnRH上)将保持结合物对TTR和GnRH受体的最大结合亲和力和血清选择性的最佳连接物长度和结合部位；目的2，评估结合物在血清中的体外半衰期，并确定允许在保护血清蛋白水解酶与TTR和GnRH受体结合之间实现最佳平衡的最佳连接物系统；目标3，评价结合物的药代动力学性质，以确定选择性结合TTR是否会延长体内半衰期，同时维持结合物的疗效。如果我们成功地实现了这一提议的目标，我们的方法将代表一种创新的技术，可能适用于提高蛋白质、寡核苷酸、寡糖、病毒样颗粒、显像剂和其他小分子药物的体内半衰期。

DESCRIPTION (provided by applicant): Harnessing transthyretin to extend the in vivo half-life of therapeutic peptides PROJECT SUMMARY: The tremendous therapeutic potential of peptides has not been fulfilled and potential peptide therapies that have failed far outnumber the successes so far. A major challenge impeding the more widespread use of peptides as therapeutics is their poor pharmacokinetic (PK) profile, due to short in vivo half-life resulting from inactivation by serum proteases and rapid elimination by kidney. Therefore, extending the in vivo half-life of peptides is clearly desirable in order for their therapeutic potential to be realized, without the need for high doses and/or frequent administration. Covalent conjugation of peptides to macromolecules (e.g. polyethylene glycol or serum proteins) has been the mainstay approach for enhancing the in vivo half-life of peptides. However, the steric hindrance of these large macromolecules often harms the binding of the peptide to its extra-cellular receptor, which compromises the pharmacodynamic (PD) properties of the peptide. The overall goal of this proposal is to develop a fundamentally new approach for enhancing the in vivo half-life of peptides without affecting its biological activity. The main hypothesis of this proposal isto test whether conjugation of peptides to a selective transthyretin (TTR, a serum protein) ligand would allow these peptide conjugates to reversibly bind to TTR in serum. This will result in enhancing the peptide's in vivo half-life, but most importantly, will maintain the binding affinityof the peptide to its receptor. A major emphasis will be on our recent discovery of the most potent and selective reversible TTR ligand to date, AG10. We have already made significant progress by synthesizing the first AG10-peptide conjugate (Conj1; with GnRH as a model peptide) and our in vitro preliminary results for Conj1 are consistent with this hypothesis. In this proposal, w will evaluate Conj1 in vivo and investigate the optimal linker system and affinity to TTR that will provide best balance between PK and PD of these AG10-GnRH conjugates. Three specific aims will be aggressively pursued: aim 1, design and synthesize a series of AG10-GnRH conjugates and determine the optimal linkers length and conjugation sites (on AG10 and GnRH) that will preserve the maximum binding affinity and serum selectivity of conjugates to both TTR and GnRH receptor; aim 2, evaluate the in vitro half-life of conjugates in serum and determine the optimal linker system that would allow for best balance between protection of GnRH against serum proteases and binding affinity to TTR and GnRH receptor; and aim 3, evaluate the pharmacokinetic properties of conjugates to determine if selective binding to TTR will increase the in vivo half-life, while maintaining the efficacy of conjugates in rats. If we successfully accomplished the goal of this proposal, our approach would represent an innovative technology that could potentially be applicable to enhancing the in vivo half-life of proteins, oligonucleotids, oligosaccharides, virus like particle, imaging agents, and other small molecule drugs.