Activity of Fully Deleted Helper-Virus Independent Adenoviral Gene Therapy Vector

描述（申请人提供）：许多疾病是由基因缺陷引起的。基因治疗的目标是通过引入正常基因或修复基因缺陷来有效治疗或治愈这些疾病。大量的研究工作已经开展，以优化基因转移载体主要是基于腺病毒和逆转录病毒。然而，基因治疗最初的前景已被常用病毒载体的生物学特性所破坏：逆转录病毒在融入人类基因组时具有内在的致突变性和致癌性；来源于腺病毒的载体诱导强烈的体液和细胞免疫反应，否定了治疗的成功。Isogenis采用双管齐下的方法来解决腺病毒载体的免疫原性问题。首先，其他研究也表明，删除病毒基因的腺病毒载体，即完全删除（fd, gutless）的免疫原性低于含有更多病毒基因的载体。尽管进行了深入的研究，但有效地生产fd腺病毒载体仍然需要使用“辅助”病毒来传递关键的腺病毒基因。Isogenis从与FDA（细胞和基因治疗部门副主任Stephanie Simek博士）的讨论中了解到，使用“辅助”病毒生产fd腺病毒载体被认为是有问题的，因为目前的纯化系统不能提供“辅助”病毒污染水平低于1 / 3 x 1010颗粒的制剂。Isogenis公司开发了一种新的腺病毒载体生产系统，该系统避免了使用“辅助”病毒和高效复制重组体。Isogenis将利用这种新的载体结构生产用于治疗血友病A和鸟氨酸转氨基甲酰基酶缺乏症（OTCD）的临床基因治疗载体。将在临床前动物模型中测试这些媒介的活性。其次，为了克服任何剩余的免疫原性，Isogenis开发了创新的免疫抑制基因转移载体。这些采用高度特异性，但有效的免疫抑制自然“否决”免疫抑制现象。简而言之，细胞在其表面表达CD8，对t细胞对其表面其他抗原的反应施加“否决权”。将在临床前动物模型中测试这些媒介的活性。这些新的腺病毒载体的发展是基因治疗重回正轨的重要一步。

DESCRIPTION (provided by applicant): Numerous diseases are caused by gene defects. The goal of gene therapy is the effective treatment or cure of these diseases by the introduction of the normal gene or repair of the gene defect. A large research effort has been mounted to optimize gene transfer vectors mostly based on adenoviruses and retroviruses. Yet, the initial promise of gene therapy has been undermined by the biology of the commonly used viral vectors: retroviruses are intrinsically mutagenic and oncogenic as they integrate into the human genome; vectors derived from adenoviruses induce vigorous humoral and cellular immune responses that negate the therapeutic success. Isogenis is taking a two pronged approach to the problem of immunogenicity in Adenoviral vectors. First, others have also shown that Adenoviral vectors deleted of viral genes, i.e. fully deleted (fd, gutless) are less immunogenic than vectors containing more viral genes. Despite intensive research, the efficient production of fd Adenoviral vectors still requires the use of 'helper' viruses to deliver crucial Adenoviral genes. Isogenis had learned from its discussion with the FDA (Dr. Stephanie Simek, Deputy Director, Division of Cellular and Gene Therapy) that the use of 'helper' viruses for the production of fd Adenoviral vectors was considered problematic as present purification systems did not deliver preparations with 'helper' virus contamination levels of less than 1-in-3 x 1010 particles. Isogenis has produced a novel fd Adenoviral vector production system that avoids the use of a 'helper' virus and replication-efficient recombinants. Isogenis will use this novel vector architecture to produce clinical gene therapy vectors for the treatment of hemophilia A and ornithine transcarbamylase deficiency (OTCD). The activity of these vectors will be tested in pre-clinical animal models. Second, to overcome any remaining immunogenicity, Isogenis has developed innovative immune inhibitory gene transfer vectors. These employ the highly specific, yet effective immune suppression of the natural "veto" immune inhibitory phenomenon. Briefly, cells expressing CD8 on their surface exert a "veto" on T-cells responding to other antigens on their surface. The activity of these vectors will be tested in pre-clinical animal models. The development of these new Adenoviral vectors is a major step forward in getting gene therapy back on track. PUBLIC HEALTH RELEVANCE: The goal of gene therapy is the cure of the disease by the introduction or repair of the defective gene. In the case of hemophilia A and OTCD, the 'missing' enzyme will be directly delivered to the resident hepatocytes. Gene therapy vectors will have to lead to sustained gene expression in their target tissue to provide a permanent cure. Immune responses directed against vector proteins generally negate any therapeutic effect. Therefore, strategies are being sought that allowed the production of effective gene therapy vectors that did no longer contain vector-derived, i.e. viral, genes. In the case of adenoviral vectors such fully deleted vectors had been designed. There efficient production depended on the use of helper viruses. Yet, the use of a helper virus was considered problematic by the FDA. Present purification systems do not deliver preparations with helper virus contamination levels of less than 1-in-3x1010. In this application, we therefore propose to investigate how w novel set of helper-virus independent fully deleted Adenoviral gene transfer vectors function in vivo.