Vascular Delivery of alpha-Sarcoglycan for LGMD2D

描述(申请人提供)：最近完成了一项在LGMD2D中的肌肉内基因治疗试验，以取代由肌肉肌酸激酶启动子控制的rAAV1传递的人α-肌聚糖基因(HSGCA)。观察基因表达长达6个月。未见不良反应。这项研究为推进血管分娩试验提供了基础和动力。在实验室中，我们已经证实rAAV.r.74可以有效地通过非人类灵长类动物的股动脉将hSGCA传递到特定的肌肉群。分娩是在四肢与体循环隔离的情况下进行的，方法是在输液部位近端临时结扎，在膝盖处安装血压袖带。遏制病毒以提高安全性是首次血管基因传递试验在肌营养不良症中的重要考虑因素。该方法安全、有效、重复性好。我们已经将这些发现提交给FDA(IND前会议)，他们接受了这种方法。此外，我们还获得了毒理学-生物分布研究的资金(丙二醛)，该研究目前正在进行中，将导致IND，允许进入临床试验。我们的中心拥有两个用于肌营养不良症基因治疗的IND，我们有一支敬业的工作人员，他们自给自足，能够为临床试验准备所有必要的法规文件(IND、RAC、IRB)。目前的拨款建议分为两个目标。AIM1是为临床试验准备的载体(自互补的rAAV.r.74.tMCK.hSGCA)。全国儿童医院在及时制造载体方面具有得天独厚的优势，因为在儿童医院研究所的基因治疗中心已经建立了载体制造设施。临床分级载体的生产可以在收到这项拨款提案授予的资金后立即开始。目的2呼吁在LGMD2D患者中进行剂量递增试验。NCH的基因治疗中心在基因治疗试验方面具有很高的资质和独特的经验。拟议的研究将是通过股动脉给药的rAAV.Rh.74.tMCK.hSGCA的剂量递增试验。瞄准股四头肌将提供一种提高肌肉力量的方法，从而延长步行时间。两个肢体将在一次治疗中进行灌流，这是FDA在IND前期会议上批准的一种方法。3名患者将接受低剂量载体(6x1011Vg/kg)，另外3名患者将接受高剂量(2x1012Vg/kg)。我们将全面研究对病毒和转基因的免疫反应，就像我们在以前的基因治疗研究中所做的那样。结果衡量标准被证明是令人满意的，并在我们的临床试验计划中广泛使用，这将决定这一方法的有效性。 与公共卫生相关：目前对肌营养不良症的治疗非常有限。支持性和呼吸系统护理有助于延长生命，但生活质量非常有限。我们已经找到了一种方法来修复四肢带状肌营养不良症的缺失基因，方法是使用一种病毒通过循环传递缺陷基因。在这项研究中，我们将替换LGMD2D患者腿部近端肌肉中的α-肌聚糖基因。目标将是延长步行时间。

DESCRIPTION (provided by applicant): An intramuscular gene therapy trial in LGMD2D to replace the human alpha-sarcoglycan gene (hSGCA) delivered by rAAV1 under control of a muscle creatine kinase promoter was recently completed. Gene expression was observed for as long as 6 months. No adverse effects were encountered. That study provided the foundation and the impetus to move forward with a vascular delivery trial. In the laboratory we have established that rAAV.rh.74 can effectively deliver hSGCA to specific muscle groups through the femoral artery in the non-human primate. Delivery is achieved with the extremity isolated from the systemic circulation using a temporary ligature proximal to the site of infusion and a blood pressure cuff at the knee. Containment of virus to promote safety is an important consideration for the first vascular gene delivery trial in muscular dystrophy. The method is safe, effective and reproducible. We have presented these findings to the FDA (pre- IND meeting) and they were receptive to this approach. In addition we have obtained funding (MDA) for the toxicology-biodistribution study that is currently underway that will lead to an IND, permitting entrie to the clinical trial. Our Center holds two INDs for muscular dystrophy gene therapy and we have a devoted staff that is self sufficient and capable of preparing all of the necessary regulatory documents (IND, RAC, IRB) for the clinical trial. The current grant proposal is divided into two aims. Aim1 is the preparation of vector for the clinical trial (self-complementary rAAV.rh.74.tMCK.hSGCA). Nationwide Children's Hospital is uniquely positioned to make vector in a timely manner because a vector manufacturing facility has been established in the Center for Gene Therapy within the Children's Hospital Research Institute. Production of clinical grade vector can start immediately upon receiving funds awarded by this grant proposal. Aim 2 calls for the performance of a dose-escalation trial in LGMD2D patients. The Center for Gene Therapy at NCH is highly qualified and uniquely experienced in gene therapy trials. The proposed study will be a dose escalation trial of rAAV.rh.74.tMCK.hSGCA delivered through the femoral artery. Targeting the quadriceps muscle will provide a means for improving muscle strength and thereby prolong ambulation. Both limbs will be perfused within a single treatment episode, an approach approved by the FDA in our pre-IND meeting. Three patients will receive low dose vector (6x1011 vg/kg) and three others will receive the high dose (2x1012 vg/kg). The immune response to virus and transgene will be fully studied as we have done in prior gene therapy studies. The outcome measures proven to be satisfactory and used extensively in our clinical trials program will determine efficacy of this approach. PUBLIC HEALTH RELEVANCE: Currently there is very limited treatment for muscular dystrophy. Supportive and respiratory care have helped prolong life but quality of life is very limited. We have found a way to restore the missing gene in limb-girdle muscular dystrophy using a virus to deliver the defective gene through the circulation. In this study we will replace the alpha-sarcoglycan gene in the proximal leg muscles in patients with LGMD2D. The objective will be to prolong ambulation.