Translating a CSF delivered AAV9-SMN for treatment of Spinal Muscular Atrophy

描述（由申请人提供）：常染色体隐性遗传病近端脊髓性肌萎缩症（SMA）是婴儿死亡最常见的遗传原因，其发生率为1:6 000-10,000活产1。最常见的形式是1型肌萎缩症或韦德尼-霍夫曼病，它导致肌张力过低和进行性无力，通常在出生后的头几个月被发现。1型SMA的诊断发生在头6个月，死亡通常发生在2岁之前。目前还没有治疗方法可以减缓或阻止疾病进展，但我们最近在新生儿SMA啮齿动物模型中利用基因传递的临床前研究表明，基因治疗可能有希望。SMA是一种有吸引力的基因治疗疾病，因为它是一种单基因缺陷，导致存活运动神经元（SMN）蛋白（低形态）数量减少，而不是完全缺乏。SMN是一种普遍表达的蛋白，在所有组织中都是必需的，当SMN基因在小鼠或具有多个拷贝的人类中过度表达时，它与毒性无关。此外，疾病严重程度与SMN蛋白水平相关，强调了SMN作为一种治疗策略的潜在治疗益处我们已经发现，早期系统地给重度SMA7啮齿动物模型注射AAV96-SMN可显著延长寿命8。这项工作发表在2010年的《自然生物技术》杂志上，以及类似的报告11-13。我们已经将这项工作扩展到50多只动物的额外研究中，这些动物已经接受了scAAV9-SMN治疗，并且在SMA小鼠的长期存活方面取得了非常一致的结果。在治疗的初始阶段，评估者是完全盲的。然而，虽然在整个研究过程中保持盲法，但要维持对生存有如此巨大影响的真正的盲状态显然是困难的。这为推进人体临床试验奠定了基础。然而，系统基因传递虽然对年轻患者有一定的优势，但在发展到体型较大和年龄较大的患者时存在局限性。首先，系统的基因传递需要大量的病毒，可能在技术和经济上都具有挑战性。其次，全身性基因传递针对所有器官，这可能会增加安全性方面的考虑，并且在具有AAV9中和抗体的患者中效果较差。我们和其他人最近发现，当AAV9被递送到脑脊液时，会产生有效的运动神经元靶向，在我们的系统基因递送研究中使用了一小部分病毒14-16。当病毒通过脑室内注射进入脑脊液时，我们和其他人已经证明，SMA小鼠存活时间明显更长，超过100天龄，这在通常在15天龄死亡的小鼠模型中也是一个显著的发现（初步数据）。这为拟议的U01申请推进到IND提交和人体临床试验奠定了基础。该U01的具体目标是：目标1：在7只SMA小鼠模型中开发脑脊液输送的AAV9-SMN的临床前数据，以支持ind前研究；目标2：优化非人灵长类动物鞘内给药，以最有效地利用scaav9 - cb靶向脊髓运动神经元。GFP目标3：评估小鼠和非人灵长类动物（非glp）给予AAV9-SMN后的毒理学和免疫反应，并向FDA提交Pre-IND。目标4：正式评估毒理学、免疫反应、生物分布和小鼠的长期表达，以支持IND向FDA （GLP）申请。目标5：准备并向FDA提交IND。

DESCRIPTION (provided by applicant): The autosomal recessive disorder proximal spinal muscular atrophy (SMA) is the most common genetic cause of infant death and has an incidence of 1:6,000-10,000 live births1. The most common form is type 1 SMA or Werdnig-Hoffman Disease which results in hypotonia and progressive weakness and is typically recognized in the first few months of life2. Diagnosis of type 1 SMA occurs in the first 6 months and death usually occurs by age two. There is no treatment available to slow or halt disease progression, but our recent preclinical studies utilizing gene delivery in newborn rodent models of SMA suggest gene therapy may hold promise. SMA is an attractive disease for gene therapy because it is a single gene defect that results in low amounts of the survival motor neuron (SMN) protein (hypomorph) versus a total deficiency3. SMN is a ubiquitously expressed protein that is essential in all tissues and is not associated with toxicity when over expressed in mice4 or in humans5 with multiple copies of the gene. In addition, disease severity correlates with SMN protein levels emphasizing the potential therapeutic benefit for SMN as a treatment strategy.1 We have discovered that systemically delivered AAV96-SMN delivered early to a severe rodent model of SMA7 results in substantial rescue of the lifespan8 . This work was published in Nature Biotechnology in 20109,10 as well as similar reports 11-13. We have expanded this work in additional studies with now over 50 animals that have been treated with scAAV9-SMN and had remarkably consistent results with long survival of SMA mice. In the initial phases of treatment the evaluator is completely blinded. However, while blinding is maintained throughout the study, it is obviously difficult to maintain a true blind status with suc a dramatic effect on survival10. This sets the stage to advance to human clinical trials. However, systemic gene delivery, while it has certain advantages for the youngest patients, has limitations when advancing to the large and older patients. First, systemic gene delivery requires significant amounts of virus, and may be technically and economically challenging. Second, systemic gene delivery targets all organs, which may increase safety considerations, and in patients with neutralizing antibodies against AAV9 be less effective. We and others have recently discovered that AAV9, when delivered to the CSF results in efficient motor neuron targeting with a fraction of the virus utilized in our systemic gene delivery studies14-16. When virus is delivered to the CSF, via intraventricular injections, we and others13,17 have demonstrated that SMA mice survive significantly longer, greater than 100 days of age, which is again a remarkable finding in a mouse model that typically dies at 15 days of age (preliminary data). This formulates the basis for the proposed U01 application to advance to IND submission and human clinical trials. The specific Aims proposed for this U01 are: Aim 1: Develop pre-clinical data of CSF delivered AAV9-SMN in the 7 mouse model of SMA to support a pre-IND Aim 2: Optimize intrathecal dosing in nonhuman primates for most efficient targeting of spinal motor neurons using scAAV9.CB.GFP Aim 3: Assess toxicology and immune response following AAV9-SMN administration in mice and nonhuman primates (non-GLP) and submit a Pre-IND to the FDA. Aim 4: Formally assess toxicology, immune response, biodistribution and long-term expression in mice that will support an IND application to the FDA (GLP). Aim 5: Prepare and Submit an IND to the FDA.