Improved Delivery of Gene Therapies to the Central Nervous System by Focused Ultrasound-Mediated Disruption of the Blood-Brain Barrier

项目摘要： 所有针对中枢神经系统的基因疗法所面临的一个主要挑战是提供治疗 通过血脑屏障（BBB），达到足够的中枢暴露，同时将毒性降至最低 在非靶组织中。用于递送腺相关病毒载体的两种最常见的给药途径 (AAV)载体是FDA批准的唯一用于神经学应用的基因转移平台， 互补的限制。静脉（IV）注射可实现在整个大脑中的广泛分布 但仅在低浓度水平，而脑实质内（IPa）注射提供高浓度的 治疗，但仅在注射部位附近。由于大多数神经系统疾病表现在多个大脑区域， 成功的基因疗法治疗将需要改进的AAV递送方法， 治疗集中和大体积覆盖。 为了解决这一关键瓶颈，我们的目标是使用 聚焦超声（FUS）介导的BBB破坏，以显著改善浓度和脑 AAV-packaged基因疗法的覆盖范围。在这个项目中，我们将调查的应用交付一个 AAV包装的micro-RNA治疗靶向抑制突变亨廷顿蛋白，该基因与 亨廷顿病（HD）。我们的初步工作表明，FUS-BBB开放增强了 IV注射的AAV 1和AAV 9载体至野生型和HD模型小鼠的靶向脑区域。我们另外 具有使用我们的人类临床FUS系统在大鼠、猴中实现大体积BBB破坏的经验 还有人类基于该初步数据，目标1将确定最佳FUS参数和AAV剂量 用于使HD模型小鼠中FUS靶向位点处的AAV浓度最大化。每种药物的安全性 治疗将根据神经炎症的标志物和创伤样损伤的迹象来表征， 组织.为了最大化脑覆盖，我们将表征安全性特征和AAV递送功效作为功能， 血脑屏障开放容积的变化。目标2将纳入目标1中获得的信息， 平衡高AAV浓度、大体积覆盖率和安全性的最佳治疗策略。我们将 评估以1-、3-、4-、5-、6-、7-、10 在mHTT降低和疾病进展的功能标志物方面，6个月和12个月时间点。在Aim中 3，所有小鼠数据将用于设计用于恒河猴中AAV递送的治疗策略。 将使用我们的人类临床FUS在这些非人灵长类动物中进行安全性和生物分布研究 系统如果成功，这里开发的策略将使AAV以更有利的方式递送到大脑。 安全性和有效性，并释放这些变革性的临床承诺 治疗

Project Summary: A major challenge faced by all gene therapies directed to the central nervous system is delivering the therapy across the blood-brain barrier (BBB) in a way that achieves adequate central exposure while minimizing toxicity in non-targeted tissues. The two most common routes of administration for delivering adeno-associated viral (AAV) vectors, the only FDA-approved gene transfer platform for neurological applications, suffer from complimentary limitations. Intravenous (IV) injection can achieve widespread distribution throughout the brain but only at low concentration levels, while intraparenchymal (IPa) injections supply a high concentration of therapy but only near the site of injection. As most neurological disorders manifest in multiple brain regions, successful gene therapy treatments will require an improved approach to AAV delivery that can achieve high therapy concentration and large volume coverage. To address this critical bottleneck, we aim to develop and validate delivery strategies using the technology of focused ultrasound (FUS)-mediated disruption of the BBB to significantly improve the concentration and brain coverage of AAV-packaged gene therapies. In this project we will investigate the application of delivering an AAV-packaged micro-RNA therapy targeting suppression of mutant Huntingtin, the gene implicated in Huntington’s disease (HD). Our preliminary work demonstrates that FUS-BBB opening enhances the delivery of IV-injected AAV1 and AAV9 vectors to targeted brain regions in wild-type and HD model mice. We additionally have experience using our human clinical FUS system to achieve large-volume BBB disruption in rats, monkeys and humans. Building off this preliminary data, Aim 1 will determine the optimal FUS parameters and AAV dose for maximizing AAV concentration at the FUS-targeted site in HD model mice. The safety profile of each treatment will be characterized in terms of markers of neuroinflammation and signs of trauma-like damage to tissue. To maximize brain coverage, we will characterize the safety profile and AAV delivery efficacy as a function of BBB opening volume in HD model mice. Aim 2 will incorporate the information gained in Aim 1 to devise an optimal treatment strategy that balances high AAV concentration, large volume coverage and safety. We will assess the safety and therapeutic efficacy of delivering an AAV-packaged microRNA to HD model mice at 1-, 3- , 6- and 12-month time points in terms of mHTT lowering and functional markers of disease progression. In Aim 3, all of the mice data will be used to devise a treatment strategy for AAV delivery in rhesus macaque monkeys. A safety and biodistribution study will be carried out in these non-human primates using our human clinical FUS system. If successful, the strategies developed here would enable AAV delivery to the brain with a more favorable safety and efficacy profile than existing alternatives and unlock the clinical promise of these transformative therapies.