Multi-serotype adenovirus vector system for targeted gene delivery to tumors

描述（由申请人提供）：缺乏有效的基因传递系统是使用基因治疗癌症的最重要障碍。目前迫切需要开发一种能够选择性、高效、安全地将基因传递到肿瘤的载体。在这一需求得到满足之前，基因疗法所代表的癌症治疗范式转变仍将无法实现。因此，这项研究计划的长期目标是通过促进新一代癌症基因治疗改进载体的发展来提高癌症治疗的疗效。为此，本提案的目标是开发一种基因传递策略，该策略将选择性地靶向肿瘤细胞，同时克服宿主的抗媒介免疫并降低正常组织的不良转导水平。要验证的中心假设是，这一目标可以通过连续使用免疫上不同的腺病毒（Ad）载体，使用多用途的趋向性修饰策略靶向肿瘤来实现。这项研究的基本原理是克服载体的免疫原性和特异性问题将是使癌症基因治疗成为临床现实的重要垂直步骤。中心假设将被检验，因此这个项目的目标将通过实现两个具体目标来实现：开发一组抗原性不同的肿瘤靶向Ad载体。具体目标2。测试设计的载体在抗ad免疫存在的情况下反复靶向肿瘤的能力。在这个项目中，一组不同的受体结合Ad纤维蛋白代表了这些分子的自然多样性，将被基因修饰以靶向人类肿瘤的主要分子标记Her2受体。这些蛋白将通过使用新颖的、合理设计的蛋白质配体、修饰体来实现Her2特异性，它们的大小、生物合成、稳定性和高亲和力使它们特别适合Ad载体靶向。为了制造这些纤维-粘附体嵌合体，我们将使用一种基于Ad纤维结构进化守恒的新型靶向策略，从而适用于各种Ad血清型。设计纤维的关键结构和功能特征将进行测试，以确认其适合广告定位。接下来，一组含有这些设计蛋白的her2靶向Ad载体将被生成，并在体外使用表达her2的肿瘤细胞进行测试。最后，通过在乳腺癌转基因动物模型中使用这些新载体，我们将证明重复基因传递到目标肿瘤的可行性，尽管先前存在抗ad免疫。在我们的研究中，这一关键可行性基因治疗范式的首次演示将具有重大意义，因为它将为人类有效基因干预的发展打开大门，从而促进该技术转化为临床应用。我们的初步发现、我们研究团队的集体专业知识以及德克萨斯大学安德森癌症中心卓越的研究环境支持了这项工作的成功。

DESCRIPTION (provided by applicant): The lack of efficient gene delivery systems is the most important barrier to the use of gene therapy for cancer. There is an urgent need to develop vectors that are capable of selective, efficient, and safe delivery of genes to tumors. Until this need is met, the paradigm shift in cancer treatment that gene therapy represents will remain unrealized. It is thus the long-term goal of this research program to improve the efficacy of cancer treatment by facilitating the development of a new generation of improved vectors for cancer gene therapy. Toward this end, the objective of this proposal is to develop a gene-delivery strategy that will selectively target tumor cells while concomitantly overcoming the anti-vector immunity of the host and reducing the level of undesired transduction of normal tissues. The central hypothesis to be tested is that this objective can be accomplished through sequential use of immunologically distinct adenovirus (Ad) vectors targeted to tumors using a versatile strategy of tropism modification. The rationale for this study is that overcoming the vector immunogenicity and specificity problems will be a major vertical step toward making cancer gene therapy a clinical reality. The central hypothesis will be tested and thereby the objective of this project will be achieved by realizing two specific aims: Specific Aim 1. Develop a panel of antigenically distinct tumor-targeted Ad vectors. Specific Aim 2. Test the ability of the designed vectors to repeatedly target tumors in the presence of anti-Ad immunity. In this project, a diverse panel of receptor- binding Ad fiber proteins that represent the natural diversity of these molecules will be genetically modified to target a major molecular marker on human tumors, the Her2 receptor. These proteins will be made Her2- specific through the use of novel, rationally designed protein ligands, affibodies, whose size, biosynthesis, stability, and high affinity make them uniquely suited for Ad vector targeting. To make these fiber-affibody chimeras, we will use a novel targeting strategy based on the evolutionary conservation of the Ad fiber structure and thus applicable to a variety of Ad serotypes. The key structural and functional features of the designed fibers will be tested to confirm their suitability for Ad targeting. Next, a panel of Her2-targeted Ad vectors containing these designed proteins will be generated and tested in vitro using Her2-expressing tumor cells. Last, through the use of these new vectors in a transgenic animal model of breast cancer, we will demonstrate the feasibility of repeated gene delivery to target tumors despite preexisting anti-Ad immunity. This first demonstration of this key feasibility of gene therapy paradigm in our study will be of major significance because it will open the door to the development of efficacious gene interventions in humans, thereby facilitating the translation of this technology into clinical use. The success of the proposed work is supported by our preliminary findings, the collective expertise of our research team, and the exceptional research environment at The University of Texas M. D. Anderson Cancer Center. PUBLIC HEALTH RELEVANCE: The proposed research is directly relevant to public health because it seeks to develop a new genetic strategy of treating and imaging human tumors. Accomplishing this goal will make it possible for the first time to repeatedly and efficiently deliver gene therapeutic and diagnostic agents to target tumors in cancer patients, most of who cannot benefit from genetic interventions at present because of the lack of appropriate gene delivery vehicles.