Novel Adeno-Associated Viral Therapy for Wet Age-Related Macular Degeneration

描述（由申请人提供）：该项目的总体目标是开发一种新型的基于基因的递送系统，以治疗新生血管性年龄相关性黄斑变性（湿性AMD），一种使人衰弱的眼部疾病。AMD是60岁以上美国人失明的主要原因，其中湿性AMD占所有AMD相关失明的90%。在美国估计有2，000，000人患有湿性AMD，并且预计到2020年湿性AMD的患病率将增长到3，000，000。湿性AMD是由视网膜下面的膜的增厚和破坏引发的。黄斑的氧气供应被破坏，身体的反应是生长新的异常血管。这些细胞开始通过视网膜后面的膜的破裂处向黄斑生长，通常使视网膜升高。这些异常的血管往往非常脆弱，并且可能泄漏或出血，导致黄斑疤痕。这种对黄斑的损伤导致快速的、不可逆的中心视力丧失。湿性AMD的标准治疗是反复眼内注射血管内皮生长因子（VEGF）抑制剂，包括单克隆抗体片段雷珠单抗。通过每月注射获得疾病的最佳控制，这是不方便的，需要频繁的办公室访问， 对任何眼部注射都是如此，与发病率有关。所提出的治疗方法是一次性注射基因递送载体，导致雷珠单抗在视网膜中持续、稳定的表达。该基因递送载体属于我们鉴定的腺相关病毒（AAV）血清型的新家族，并且其表现明显优于先前可用的基因转移技术。重组AAV在非分裂组织中提供稳定的基因表达而不整合到基因组中，从而避免潜在的整合相关不良事件;此外，AAV本身是非致病性的。然而，先前已知的AAV血清型在体内转导细胞方面不是非常有效;新的AAV血清型在视网膜中提供更高水平的基因表达，使得能够以较低剂量的载体进行安全和治疗性的基因递送。基因转移将靶向RPE和光感受器，以便将治疗性蛋白质直接递送到眼睛的适当部分。第一阶段SBIR应用的直接目标是识别和开发最佳临床候选药物。已经确定了用于基于视黄酸的基因转移的最佳AAV血清型和启动子。将通过替换前导序列和定制密码子使用来优化雷珠单抗的表达，以在人组织中表达。将通过以下方式进行原理证明研究：1）在视网膜中人VEGF表达引起的视网膜脱离小鼠模型中证明治疗剂的疗效，和2）在非人灵长类动物眼睛中证明和确认先前达到的雷珠单抗表达水平，该物种的视网膜在结构上与人眼最接近。这将通过安全性/毒性研究和临床试验用于未来进展。 公共卫生相关性：视网膜相关性黄斑变性（AMD）是导致失明的主要原因之一。预计到2020年，美国新生血管性（湿性）AMD的患病率将增加至近300万。现有的治疗方法有效地限制了 但是在药物成本和需要通过玻璃体内注射频繁给药以及伴随的安全性问题方面存在问题。该提案启动了一种新的实验性疗法的临床开发，该疗法涉及使用载体的一次性遗传递送系统，该载体提供药物的长期表达，这对患者来说可能更安全且负担更小。

DESCRIPTION (provided by applicant): The overall goal of this project is to develop a novel gene-based delivery system to treat neovascular age- related macular degeneration (wet AMD), a debilitating ocular disease. AMD is the leading cause of blindness in Americans over 60 years of age, with wet AMD accounting for 90% of all AMD-related blindness. An estimated 2,000,000 people in the United States suffer from wet AMD, and it is expected that the prevalence of wet AMD will grow to 3,000,000 by 2020. Wet AMD is initiated by a thickening and disruption of the membrane underlying the retina. The oxygen supply to the macula is disrupted and the body responds by growing new, abnormal blood vessels. These begin to grow through the breaks of the membrane behind the retina towards the macula, often raising the retina. These abnormal blood vessels tend to be very fragile, and can leak or bleed, causing scarring of the macula. This damage to the macula results in rapid, irreversible central vision loss. The standard of care for wet AMD is repeated intraocular injections of vascular endothelial growth factor (VEGF) inhibitors, including the monoclonal antibody fragment ranibizumab. Optimal control of disease is obtained with monthly injections, which are inconvenient, require frequent office visits, and as is true for any injection into the eye, are associated with morbidity. The proposed therapeutic would be a one-time injection of a gene delivery vehicle, resulting in persistent, stable expression of ranibizumab in the retina. The gene delivery vector belongs to a new family of adeno-associated virus (AAV) serotypes that we identified and which perform substantially better than previously available gene transfer technologies. Recombinant AAV gives stable gene expression in non-dividing tissues without integrating into the genome, and thus avoids potential integration-associated adverse events; furthermore, AAV itself is non-pathogenic. Previously known serotypes of AAV, however, are not very efficient at transducing cells in vivo; the novel AAV serotypes give higher levels of gene expression in the retina, enabling safe and therapeutic gene delivery at lower doses of vector. Gene transfer will be targeted to the RPE and photoreceptors in order to deliver the therapeutic protein directly to the appropriate part of the eye. The immediate goal of this Phase I SBIR application is to identify and develop the optimal clinical candidate. The optimal AAV serotype and promoter for retinal-based gene transfer have been determined. Expression of ranibizumab will be optimized by replacement of the leader sequence and tailoring codon usage for expression in human tissues. Proof of principle studies will be performed by: 1) demonstration of efficacy of the therapeutic in a mouse model of retinal detachment caused by human VEGF expression in the retina, and 2) demonstration and confirmation of previously achieved levels of ranibizumab expression in the non-human primate eye, the species whose retina is closest in structure to the human eye. This will be used for future progression through safety/tox studies and clinical trials. PUBLIC HEALTH RELEVANCE: Age-related macular degeneration (AMD) is one of the leading causes of blindness. The prevalence of neovascular (wet) AMD in the United States is expected to increase to nearly 3 million by 2020. Existing treatments are effective in limiting the progression of the disease but are problematic in both cost of drug and the requirements for frequent administration by intravitreal injection with attendant safety problems. This proposal initiates the clinical development of a new experimental therapy which involves a one-time genetic delivery system using a vector that provides long term expression of the drug which is potentially safer and less burdensome to the patient.