Barriers to achieving efficient gene therapy

该方案的目标是探索产生新的AAV载体的方法，以克服前病毒载体的障碍 现有的载体中和抗体(NAB)可实现体内高效的基因转移。体内给药 AAV载体在各种遗传性疾病的临床前和临床模型中显示出了良好的前景。这个 迄今为止的主要挑战包括宿主免疫反应和由于有限的转导效率 载体的趋向性和载体向靶细胞的不良传递。AAV血清型(AAV)已被鉴定 作为肝脏导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基因治疗的人体临床试验对宿主载体免疫仍有很多了解 T细胞和B细胞对载体的天然免疫和激活等相互作用 及其转基因产品。宿主免疫的一个最重要的方面是中和的影响 抗体(NAB)对转导效率的影响。针对AAV载体衣壳蛋白的NAB导致大量 在动物的临床前研究中证明，全身给药时转导的减少 模型和人体临床试验中。我们已经将预先存在的NAB的阈值滴度表征为 对非人灵长类动物aavs基因转移的妥协。预先存在的NAB钳工超过1：10 显著减少肝细胞转导，剂量为3x10^genonne/kg。基于我们的 在对人体样本的调查中，我们预测美国25%的人类将不适合全身 AAVS载体的交付。能够逃脱中和的工程载体将提供更一般的 和有效的解决方案。在这个项目中，我们将在AAV结构的指导下使用多种方法 最终目标是产生一种保留AAVs的高肝脏趋向性的AAVs-Prime(AAVs‘)载体 对人类的中和反应更具抵抗力。 相关性(请参阅说明)： 许多遗传性代谢性疾病，如OTC缺乏，缺乏有效的治疗方法。腺体- 联合载体介导的肝基因治疗有可能为治愈或治疗提供另一种选择 这些危及生命的疾病。该项目旨在开发改进的载体，以克服障碍 以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.