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

描述(申请人提供)：常染色体隐性遗传病近端脊髓性肌萎缩症(SMA)是导致婴儿死亡的最常见的遗传原因，发病率为1：6,000-10,000活产1。最常见的形式是1型SMA或Werdnig-Hoffman病，它导致低张力和进行性虚弱，通常在生命的头几个月被发现2。1型SMA的诊断发生在头6个月，死亡通常发生在两岁之前。目前还没有可用的治疗方法来减缓或阻止疾病的进展，但我们最近在SMA新生啮齿动物模型中利用基因传递进行的临床前研究表明，基因治疗可能是有希望的。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)的数量较少，而不是完全缺陷3。SMN是一种普遍表达的蛋白质，在所有组织中都是必不可少的，当在小鼠或具有多个基因副本的人类中过度表达时，与毒性无关。此外，疾病的严重性与SMN蛋白水平相关，强调SMN作为一种治疗策略的潜在治疗益处。1我们发现，系统地将AAV96-SMN早期注射到严重的SMA7啮齿动物模型中，可以显著挽救生命8。这项工作发表在2010年9月10期的《自然生物技术》以及类似的11-13期报告中。我们在更多的研究中扩展了这项工作，现在有超过50只动物接受了scAAV9-SMN的治疗，并获得了与SMA小鼠长期存活非常一致的结果。在治疗的最初阶段，评估者完全失明。然而，尽管在整个研究过程中保持失明，但由于SUC对存活率有显著影响，显然很难维持真正的失明状态。这为推进人类临床试验奠定了基础。然而，系统基因传递虽然对最年轻的患者有一定的优势，但在推广到较大和较年长的患者时有局限性。首先，系统性基因传递需要大量的病毒，而且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考虑，并且在抗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被输送到脑脊液时，会导致有效的运动神经元靶向与我们系统基因传递研究中使用的一部分病毒14-16。当病毒通过脑室注射进入脑脊液时，我们和其他13，17人已经证明了SMA小鼠的存活时间显著延长，超过100天，这在通常15天龄死亡的小鼠模型中再次是一个显著的发现(初步数据)。这为建议的U01申请推进到IND提交和人体临床试验奠定了基础。为U01提出的具体目标是：目标1：在7只SMA小鼠模型中建立脑脊液传递AAV9-SMN的临床前数据，以支持Pre-IND目标2：优化非人类灵长类动物鞘内给药，以使用scAAV9-CB.GFP最有效地靶向脊髓运动神经元。目标3：评估AAV9-SMN在小鼠和非人灵长类动物(Non-GLP)注射后的毒理学和免疫反应，并向FDA提交Pre-IND报告。目的4：正式评估IND在小鼠体内的毒理学、免疫反应、生物分布和长期表达，以支持IND向FDA(GLP)申请。目标5：准备一份IND并提交给FDA。

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.