Diverse Strategies to Correct the Dystrophin Gene Using Vascular Delivery (U54)

该U 54基因治疗方案的前提是，通过血管输送可以在杜氏肌营养不良症（DMD）患者中获得临床上有意义的结果。与FDA的讨论表明，这将以逐步的方式向前推进，其中临床试验中的局部血管输送将先于全身血管输送。我们的建议围绕着这个中心点，通过股动脉将基因输送到腿部是起点。在项目1中，rAAV.micro-dystrophin将用于恢复缺失的dystrophin蛋白。在项目2中，一个新的基因，CT GalNAc转移酶（也称为GALGT 2）将通过AAV递送。这两种方法，通过完全不同的机制，加强削弱的肌肉膜，负责渐进的肌肉纤维损伤和损失与脂肪和结缔组织的替代。本提案中提出的研究将迈出通过血管途径进行临床试验的第一步。在申请IND之前，必须解决U 54中提到的几个考虑因素，包括病毒的递送方法和免疫原性及其 货物.我们将在恒河猴中研究这一点，恒河猴是一种在解剖学和免疫系统方面与人类具有密切同源性的理想系统。我们将使用rAAV 8，这是一种病毒血清型，我们发现它可以穿过小型和大型动物物种的血管屏障，为猴子研究奠定了基础。此外，我们可以通过预先筛选中和抗体来递送这种血清型，其中有或没有对AAV 8的预先免疫。我们还可以测试各种免疫抑制方案，以确定免疫抑制是否对患者的基因转移是必要的（如用因子IX进行的人类基因转移研究所预测的）。猴子还提供了一条血管进入途径，与我们在临床上遇到的情况非常相似。因此，我们将通过球囊导管在区室化系统中递送携带微肌养蛋白或GALGT 2的rAAV，以提供病毒的安全通道并保护宿主免于病毒传播到不需要的靶标。在完成这些研究后，我们将有足够的信息向FDA申请这两种有前途的产品的IND。我们认为，这两项工作都应继续进行， 诊所，每一个都有自己的优势。这两种基因治疗方法的I期安全性试验的完成为进一步的血管递送打开了大门，从而为患者带来了具有临床意义的结果。

The premise for this U54 gene therapy proposal is that clinically meaningful results can be achieved by vascular delivery in patients with Duchenne muscular dystrophy (DMD). Discussions with FDA indicate that this will move forward in a stepwise fashion whereby regional vascular delivery will precede systemic vascular delivery for clinical trials. Our proposal revolves around this central point and gene delivery to the legs through the femoral artery is the starting place. In project 1, rAAV.micro-dystrophin will be used to restore the missing dystrophin protein. In project 2, a novel gene, CT GalNAc transferase (also called GALGT2) will be delivered by AAV. Both approaches, through entirely different mechanisms, reinforce the weakened muscle membrane, responsible for progressive muscle fiber damage and loss with replacement by fat and connective tissue. The studies presented in this proposal will take the first steps leading to a clinical trial through a vascular route. There are several considerations addressed in this U54 that must be resolved before application for IND, including method of delivery and immunogenicity of the virus and its cargo. We will study this in the rhesus macaque, an ideal system with close homology to the human anatomically and in the immune system. We will use rAAV8, a viral serotype that we found crosses the vascular barrier in both small and large animal species, setting the stage for the monkey studies. In addition, we can deliver this serotype with and without pre-exising immunity to AAV8 by pre-screening for neutralizing antibodies. We can also test various immunosuppressive protocols to establish if immune suppression will be necessary for gene transfer in patients (as predicted by the human gene transfer studies with factor IX). The monkey also provides a vascular route of entry that closely simulates that which we will encounter clinically. Thus, we will deliver rAAVS carrying micro-dystrophin or GALGT2 in a compartmentalized system through a balloon catheter to provide safe passage for the virus and to protect the host from spread of virus to unwanted targets. Upon completion of these studies we will have enough information to apply to FDA for an IND for both of these promising products. We feel that both should be carried forward to the clinic, each very promsing in its own right. Completion of phase I safety trials for both of these gene therapy approaches opens the gate for further vascular delivery leading to clinically meaningful results for patients.