Choroid Plexus-Directed Gene Therapy for Alpha-Mannosidosis

 描述(由申请人提供)：这项提案将两种成熟的阿尔法甘露糖症动物模型中的一系列创新的AAV基因治疗实验与临床前毒理学研究相结合，以开发一条通往脑脊液(CSF)输送的这种疾病的基因治疗的首个人类临床试验的道路。卡勒实验室通过有效地转导脉络丛上皮细胞，使用脑脊液导向的AAV5基因疗法治疗了孟克斯病的小鼠模型。脉络丛(CP)是高度血管化的结构，投射到脑室。CP的极化上皮细胞产生 并分泌大量的蛋白质。溶酶体储存疾病(LSD)可能受益于CP靶向的方法，因为AAV转导导致持续的外体转基因表达，并且CP上皮细胞的周转速度较慢。沃尔夫实验室已经证明，将AAV基因转移到LSD动物模型的大脑中可以介导实质性但不完全的细胞纠正和临床改善。靶向脑脊液流动的好处是它延伸到整个脑室系统，到达蛛网膜下腔，分子最终从那里到达整个大脑。鞘内注射纯化的重组溶酶体酶(酶替代疗法，ERT)已在动物模型和最近的人类临床试验中成功地改善了一些脑病理。然而，这种方法的一个主要缺点是由于重组酶的半衰期很短，需要重复鞘内注射。另一种可选的长期策略是用AAV载体重塑CP上皮细胞，以分泌感兴趣的酶。CP上皮细胞的周转速度非常慢，因此这种方法可以产生一种永久性的酶产生来源，用于分泌到脑脊液并渗透到脑结构。此外，脑室注射AAV载体可以将正常基因输送到一些实质细胞，然后实质细胞也可以将正常酶分泌到细胞外空间，以便输送到其他细胞。一项为期两年的NIH长凳到床边奖(R21等值)支持了在阿尔法甘露糖症(AMD)动物模型中对这一假说的初步评估，AMD是一种典型的LSD。这项U01提案扩大了这一努力，目标是在3-4年内完成提交I期临床试验IND所需的临床前研究。我们建议：1)评估相对能力 该研究的目的是：1)确定不同的AAV载体血清型，以支持在AMD小鼠模型中进行脑脊液导向的AAV转导，并测试AMD猫的大脑中最有希望的血清型，目的是确定在人类临床试验中最有可能产生最大益处的载体；2)确定AMD患者的临床和生化特征，用于未来临床试验的结果衡量；以及3)对非人类灵长类动物进行临床前毒理学研究，并获得监管部门的批准，使首个针对AMD的人内基因治疗试验获得批准。这对LSD领域的临床实践的潜在影响很大，因为如果成功实现拟议的目标，AMD患者和其他患有脑部疾病的LSD患者目前面临的最大健康障碍将被绕过。

 DESCRIPTION (provided by applicant): This proposal links a series of innovative AAV gene therapy experiments in two well-established animal models of alpha-mannosidosis with preclinical toxicology studies to develop a path forward to a first-in-human clinical trial of cerebrospinal fluid (CSF)-delivered gene therapy for this illness. The Kaler lab has treated a mouse model of Menkes disease using CSF-directed AAV5 gene therapy via efficient transduction of choroid plexus epithelia. The choroid plexuses (CP) are highly vascularized structures that project into the ventricles of the brain. The polarized epithelia of the CP produce CSF and secrete a large number of proteins. Lysosomal storage diseases (LSDs) could potentially benefit from a CP-targeted approach because AAV transduction results in sustained episomal transgene expression and CP epithelia have a slow rate of turnover. The Wolfe lab has shown that AAV gene transfer into the brains of animal models of LSDs can mediate substantial but incomplete cellular correction and clinical improvement. The advantage of targeting CSF flow is that it extends throughout the ventricular system to the subarachnoid space, from which molecules ultimately reach the entire brain. Intrathecal delivery of purified recombinant lysosomal enzyme (enzyme replacement therapy, ERT) has been successful in ameliorating some brain pathology in animal models and recently in a human clinical trial. However, a major drawback to this approach is the need for repeated intrathecal injections due to short half- lives of recombinant enzymes. An alternative long-term strategy is to remodel CP epithelial cells with an AAV vector to secrete enzyme of interest. CP epithelia have an extremely slow turnover rate, thus this approach could generate a permanent source of enzyme production for secretion into the CSF and penetration to brain structures. Furthermore, intraventricular injection AAV vectors can deliver the normal gene to some of the parenchymal cells, which can then also secrete normal enzyme into extracellular spaces for delivery to other cells. A two-year NIH Bench-to-Bedside Award (R21 equivalent) supported the initial evaluation of this hypothesis in animal models of alpha-mannosidosis (AMD), a prototypical LSD. This U01 proposal expands that effort with the goal of completing the pre-clinical studies needed to submit a phase I clinical trial IND in 3-4 years. We propose to: 1) Evaluate the relative abilities of different AAV-vector serotypes to support CSF- directed AAV transduction in a mouse model of AMD and test the most promising serotypes in the much larger brain of the AMD cat, with the goal of identifying the vector that is most likely to produce the greatest benefit in human clinica trials; 2) Establish clinical and biochemical features in AMD patients for outcome measures in a future clinical trial; and 3) Perform preclinical toxicology studies in non-human primates and develop regulatory approval for a first-in-human gene therapy trial for AMD. The potential impact on clinical practice in the field of LSD is high since, if the proposed aims are successfully achieved, the largest current barriers to health for patients with AMD and other LSDs with brain disease would be circumvented.