avb6-directed molecular imaging and therapy

 描述(申请人提供)：这项提案的总体目标是进一步研究整合素亚型αvβ6，作为癌症分子成像和治疗的靶点。整合素αvβ6是一种上皮特异性细胞表面受体，在健康人中检测不到 在成人上皮细胞中表达显著上调，但在多种上皮源性癌症中显著上调。以前在胰腺癌、卵巢癌、肺癌和鳞状细胞癌中发现，最新的报道表明αvβ6的表达也预示着乳腺癌从原位癌向浸润性癌的转变，预示着结肠癌患者的不良预后，并通过上调MMP2在前列腺癌中促进骨溶解。总体而言，这使得αvβ6成为分子成像和治疗的重要靶点。我们提出了一种基于靶向多肽的方法来开发新的αvβ6特异性显像剂和αvβ6特异性疗法。我们将使用多聚体方法进一步提高靶向亲和力和白蛋白结合基序，以改善我们目前的αvβ6靶向多肽PEG28-A20FMDV2(K16R)-PEG28的药代动力学特性。所有化合物都将在体外和体内通过ELISA和细胞结合研究进行亲和力和选择性筛选，并将评估它们的血清稳定性， 基于αvβ6-亲和力和5 NM，选择性1000倍，αvβ6(+)细胞结合1小时50%和2小时后血清稳定性95%的先导化合物被用于荷瘤小鼠的体内成像研究。基于小鼠药代动力学和放射性标记策略的先导化合物也将在非人类灵长类动物中进行研究。我们将使用PEG28-A20FMDV2(K16R)-PEG28作为两种治疗策略的概念验证载体：i)D(KLAKLAK)2(促凋亡多肽)和ii)基于胶束的紫杉醇(PTX)纳米载体配方。在小鼠体内试验之前，将在DX3/mTFL/ITGB6(αvβ6阳性)和DX3/mTFL(αvβ6阴性)细胞中进行体外疗效评估。正电子发射断层扫描(PET)和生物发光成像(BLI)将被用来跟踪体内的生物分布和测量这些靶向治疗的疗效。这项提议汇集了一支跨学科的研究团队，他们拥有放射化学和分子成像(Sutcliffe，PI)、生物统计学(Beckett)、非人灵长类成像(Tarantal)、物理和成像仪器(Cherry)以及外科肿瘤学(Bold)的专业知识，并有成功合作和富有成效的研究历史。这项建议将利用最先进的临床前影像资源(包括非人类灵长类动物)以及新的放射化学和GMP资源，以促进快速转化到临床。

 DESCRIPTION (provided by applicant): The overall goal of this proposal is to further investigate the integrin subtype αvβ6 as a target for molecular imaging and therapy of cancer. The integrin αvβ6 is an epithelial-specific cell surface receptor that is undetectable in healthy adult epithelium but is significantly up-regulated in a wide range of epithelial derived cancers. Previously indicated in pancreatic, ovarian, lung and squamous cell carcinoma, most recent reports indicate the expression of αvβ6 also predicts the transition from DCIS to invasive carcinoma in breast cancer, is indicative of a poor outcome for patients with colon cancers, and promotes osteolysis through the up-regulation of MMP2 in prostate cancer. Overall this makes αvβ6 a significant target for both molecular imaging and therapy. We propose a targeted-peptide based approach to develop both novel αvβ6 specific imaging agents and αvβ6 specific therapies. We will use multimerization approaches to further improve target affinity and albumin binding motifs to improve pharmacokinetic properties of our current αvβ6 targeting peptide PEG28-A20FMDV2 (K16R)-PEG28. All compounds will be screened in vitro and in vivo for affinity and selectivity in ELISA and cell binding studies, their serum stability will be assessed, and the lead compounds taken forward to in vivo imaging studies in tumor-bearing mice based on αvβ6-affinity <5 nM, selectivity >1000 fold, αvβ6 (+) cell binding >50% at 1 h and serum stability >95% after 2 h. The lead compounds, based on murine pharmacokinetics and radiolabeling strategies, will also be investigated in nonhuman primates. We will use PEG28-A20FMDV2 (K16R)-PEG28 as a proof of concept delivery vehicle for two therapeutic strategies: i) D (KLAKLAK) 2 (a pro-apoptotic peptide) and, ii) a micelle-based nanocarrier formulation of paclitaxel (PTX). Efficacy will be assessed in vitro in DX3/mTFL/ITGB6 (αvβ6-positive) and DX3/mTFL (αvβ6-negative) cells prior to in vivo studies in mice. Positron emission tomography (PET) and bioluminescence imaging (BLI) will be used both to track in vivo biodistribution and measure therapeutic efficacy of these targeted therapies. This proposal brings together an interdisciplinary team of investigators with expertise in radiochemistry and molecular imaging (Sutcliffe, PI), biostatistics (Beckett), nonhuman primate imaging (Tarantal), physics and imaging instrumentation (Cherry) and surgical oncology (Bold), with a history of successful collaboration and productive research. This proposal will utilize the state of the art preclinical imaging resources (including nonhuman primate) as well as new radiochemistry and GMP resources to facilitate rapid translation to the clinic.