Micellar Nanocarriers with Controlled Multivalent Ligand Presentation

描述(申请人提供)：除了增强渗透和滞留(EPR)效应外，纳米载体还可以通过表面嫁接目标配体来赋予肿瘤细胞上上调的受体或成分亲和力，从而积极地进行靶向治疗，以提高治疗效果并将副作用降至最低。然而，靶向部分的存在对纳米载体的药代动力学、生物分布和肿瘤蓄积的影响仍有待量化，在某些情况下可能存在争议。除肿瘤生理等生物学因素外，靶向部分对体内肿瘤生长的影响 纳米载体的路径和命运应取决于靶向部分的性质及其在纳米载体表面的空间分布。与病毒中受到良好调控的结构控制相反，现有的纳米载体对配体的空间分布和配体相对于颗粒表面的取向存在有限的结构控制，这决定了配体结合位点的可用性。基于两亲性3-螺旋多肽-聚乙二醇偶联物，我们设计并合成了尺寸在10-20 nm之间的所谓的“3-螺旋胶束”。用正电子发射断层扫描(PET)证实了放射性标记的3-螺旋胶束的体内稳定性，聚乙二醇化15 nm胶束的α循环半衰期为~28h。3-螺旋胶束克服了制备有效纳米载体所遇到的尺寸、货物泄漏、体内稳定性和清除性等困难。通过将目标配体连接到胶束表面，我们应该能够实现对配体呈现的低聚状态的控制。我们建议(1)合成尺寸为10-20 nm的配基修饰纳米载体，并控制配基间距和配基呈现的局部多价性；(2)进行体外研究，以评估载体内化作为配基密度和多价性的函数；以及(3)进行体内研究 使用乳腺癌和前列腺癌两种肿瘤模型，评估配基密度、配基间距和配基簇集对这些新的3-螺旋胶束的药代动力学和生物分布的影响。我们还将对有希望的胶束纳米颗粒进行免疫原性测试，以确保它们作为纳米载体的临床可行性。螺旋卷曲是控制配体递呈的最常见的蛋白质基序。靶向胶束是回答有关主动靶向纳米载体设计原理的几个关键问题的理想模型体系。实际上，我们的研究是基于胶束纳米颗粒，这些纳米颗粒已经显示出作为纳米载体的许多理想属性。拟议的研究可能会带来有效的治疗方法，结合了通过EPR效应进行被动靶向和主动靶向治疗乳腺肿瘤的综合优势。

DESCRIPTION (provided by applicant): In addition to the enhanced permeation and retention (EPR) effect, nanocarriers can be actively targeted to improve the efficacy of treatment and minimize side effects by surface grafting target ligands to impart an affinity for cellular upregulated receptors or components on tumor cells. However, the effects of the presence of a targeting moiety on the pharmacokinetics, biodistribution and tumor accumulation of nanocarriers still remain to be quantified and can be controversial in some cases. In addition to the biological factors such as tumor physiology, the influence of a targeting moiety on the in vivo pathway and fate of nanocarriers should depend on the nature of the targeting moiety as well as its spatial distribution on the nanocarrier surface. In contrast to well-regulated structural contrl seen in viruses, there is limited structural control in existing nanocarriers over the spatial distribution of ligands and the orientation of ligand relative to the particle surface that determies the availability of ligand binding sites. We have designed and synthesized so-called "3-helix micelles" that are uniform in size from 10-20 nm based on amphiphilic 3-helix peptide-polyethylene glycol (PEG) conjugates. The in vivo stability of the radiolabeled 3-helix micelles have been confirmed using positron emission tomography (PET) and the alpha circulatory half-life of PEGylated 15 nm micelle is ~28 h. 3-helix micelles already overcame several difficulties encountered to prepare effective nanocarriers such as size, cargo leakage, in vivo stability and clearance. Upon attaching target ligands to the surface of micelles, we should be able to achieve control over oligomeric state of ligand presentation. We propose to (1) synthesize ligand decorated nanocarriers, 10-20 nm in size with control over the inter-ligand distance and local multivalency of ligand presentation; (2) perform in vitro studies to evaluate the carrier internalization as a function of ligand density and multivalency; and (3) carry out in vivo studies use two cancer models, i.e. breast cancer and prostate cancer, to evaluate the effect of ligand density, inter-ligand distance and ligand clustering on the pharmacokinetics and biodistribution of these new 3-helix micelles. We will also perform immunogenicity tests on promising micellar nanoparticles to ensure their clinical viability as nanocarriers. Coiled-coil is the most common protein motif to control ligand presentation. The targeted micelles are ideal model system to answer several critical questions regarding the design principle of active targeting nanocarriers. Practically, our studies are based on micellar nanoparticles that have already demonstrated many desirable attributes as nanocarriers. Proposed studies may potentially lead to effective therapeutics with the combined advantages of both passive targeting via EPR effect and active targeting for breast tumors.