Barriers to achieving efficient gene therapy

该提案的目标是探索产生新的AAV载体的方法，以克服前病毒的障碍。 现有的载体中和抗体（NAb）来实现体内有效的基因转移。体内递送 AAV载体在遗传性疾病的多种临床前和临床模型中显示出前景。的 迄今为止，主要的挑战涉及宿主免疫应答和由于有限的细胞毒性而导致的低转导效率。 载体向性和载体向靶细胞的不良递送。AAV血清型8（AAVS）已被鉴定 作为肝脏定向基因转移的最佳临床候选载体，目前正在进行评估。 血友病B基因治疗人体临床试验关于宿主-载体免疫， 相互作用，例如先天免疫的作用以及T细胞和B细胞对载体的活化 及其转基因产物。宿主免疫最重要的方面之一是中和的影响 抗体（NAb）对转导效率的影响。针对AAV载体衣壳的NAb导致了实质性的免疫应答。 如动物临床前研究所示，全身给药时转导减少 模型和人体临床试验。我们已经表征了预先存在的NAb的阈值滴度， 在非人灵长类动物中进行AAVS基因转移。预先存在的NAb过滤器超过1：10 在3x 10 ^^基因拷贝/kg的剂量下显著减少肝细胞转导。基于我们 根据对人类样本的调查，我们预测美国25%的人将不适合全身性 AAVS载体的递送。可以逃脱中和的工程载体将提供更普遍的 有效的解决方案。在这个项目中，我们将采用由AAV结构引导的多重方法， 最终目的是产生“AAVS-prime”（AAVS '）载体，其保留AAVS'）的高肝向性， 在人体内对中和作用更有抵抗力。 相关性（参见说明）： 许多遗传性代谢疾病，如OTC缺乏症，缺乏有效的治疗方法。腺- 相关载体介导的肝基因治疗有可能提供一种替代治愈或治疗 这些危及生命的疾病本项目旨在开发改良载体以克服这些障碍 达到有效的治疗效果。

The goal of this proposal is to explore ways to generate a novel AAV vector to overcome the barrier of pre- existing vector neutralizing antibodies (NAbs) to achieve efficient gene transfer in vivo. In vivo delivery of AAV vectors has shown promise in a variety of pre-clinical and clinical models of inherited disorders. The major challenges to date involve host immune responses and poor transduction efficiency due to limited vector tropism and poor delivery of the vector to the target cell. AAV serotype 8 (AAVS) has been identified as the best Clinical Candidate vector for liver-directed gene transfer and is currenfiy being evaluated in a human clinical trial for gene therapy of hemophilia B. Much is still being learned about host-vector immune interactions such as the effect of innate immunity and activation of T cells and B cells against the vector and its transgene product. One of the most important aspects of host immunity is the impact of neutralizing antibodies (NAb) on transduction efficiency. NAb against the AAV vector capsid results in substantial reduction in transducfion when administered systemically, as demonstrated in preclinical studies in animal models and in human clinical trials. We have characterized the threshold titer of pre-existing NAb that is compromising to AAVS gene transfer in nonhuman primates. Pre-existing NAb fiters in excess of 1:10 substantially diminish hepatocyte transduction at the dose of 3x10^^ genonne copies/kg. Based on our survey in human samples, we predict that 25% of humans in the USA will not be suitable for systemic delivery of AAVS vector. Engineered vectors that can escape neutralization would provide a more general and effective solufion. In this project, we will employ mulfiple approaches guided by AAV structures with the ultimate aim to generate an "AAVS-prime" (AAVS') vector that retains the high liver tropism of AAVS and is more resistant to neutralization in humans. RELEVANCE (See instructions): Many inherited metabolic diseases, such as OTC deficiency, are lacking effective treatments. Adeno- associated vector-mediated hepatic gene therapy has the potential to provide an alternative to cure or treat these life-threatening disorders. This project aims to developing improved vectors to overcome the barriers to achieving efficient therapeutic effects.