avb6-directed molecular imaging and therapy

 描述（由申请人提供）：本提案的总体目标是进一步研究整合素亚型α v β 6作为癌症分子成像和治疗的靶点。整合素α v β 6是一种上皮特异性细胞表面受体，在健康人中检测不到。 但在广泛的上皮来源的癌症中显著上调。先前在胰腺癌、卵巢癌、肺癌和鳞状细胞癌中有研究表明，最近的报告表明，α v β 6的表达还可预测乳腺癌从DCIS向浸润性癌的转变，表明结肠癌患者的预后不良，并通过前列腺癌中MMP 2的上调促进骨质溶解。总的来说，这使得α v β 6成为分子成像和治疗的重要靶标。我们提出了一种基于靶向肽的方法来开发新的α v β 6特异性显像剂和α v β 6特异性治疗。 我们将使用多聚化方法来进一步改善靶向亲和力和白蛋白结合基序，以改善我们目前的α v β 6靶向肽PEG28-A20FMDV 2（K16 R）-PEG28的药代动力学性质。将在体外和体内筛选所有化合物在ELISA和细胞结合研究中的亲和力和选择性，将评估其血清稳定性， 基于α v β 6-亲和力<5 nM，选择性> 1000倍，1小时α v β 6（+）细胞结合> 50%，2小时后血清稳定性> 95%，将先导化合物用于荷瘤小鼠体内成像研究。基于鼠药代动力学和放射性标记策略，还将在非人灵长类动物中研究先导化合物。我们将使用PEG 28-A20FMDV 2（K16R）-PEG 28作为两种治疗策略的概念递送载体的证明：i）D（KLAKLAK）2（促凋亡肽）和ii）紫杉醇（PTX）的基于胶束的纳米载体制剂。在小鼠体内研究之前，将在DX3/mTFL/ITGB6（α v β 6阳性）和DX3/mTFL（α v β 6阴性）细胞中体外评估疗效。正电子发射断层扫描（PET）和生物发光成像（BLI）将用于跟踪体内生物分布和测量这些靶向治疗的疗效。该提案汇集了一个跨学科的研究人员团队，他们具有放射化学和分子成像（Sutcliffe，PI），生物统计学（Beckett），非人灵长类动物成像（Tarantal），物理和成像仪器（Cherry）和外科肿瘤学（Bold）的专业知识，具有成功合作和富有成效的研究历史。该提案将利用最先进的临床前成像资源（包括非人灵长类动物）以及新的放射化学和GMP资源，以促进快速转化为临床。

 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.