Pre-clinical development of SPY-DYS45-55, a CRISPR/Cas9 platform for Duchenne muscular dystrophy

MyoGene Bio是一家致力于开发尖端肌肉基因疗法的初创公司 疾病在这项提案中，该公司将推进我们潜在的治疗， SPY-DYS 45 -55，一种用于Duchenne肌营养不良症（DMD）的CRISPR/Cas9基因编辑平台 与加州大学洛杉矶分校的研究伙伴合作。杜兴是一个毁灭性的肌肉萎缩 由DMD基因的框架外突变引起的无法治愈的疾病。SPY-DYS45-55 去除DMD中的突变热点，以恢复所有杜氏突变的一半的阅读框架。 通过产生符合读码框的外显子45-55缺失来治疗患者。这种删除与一种非常 人类Becker肌营养不良症患者的轻度表型。基因编辑的系统递送 平台到肌肉是一个重大的挑战。某些血清型重组腺相关病毒 病毒（AAV）对骨骼肌和心脏具有嗜性。然而，免疫 对病毒的应答禁止重复施用AAV。此外，预先存在 某些个体的免疫力（预计高达70%的成年人存在），排除了他们的免疫力。 有资格享受这种待遇。快速通道提案的目标是设计 应对这些挑战的战略。在第一阶段，我们将确定一个最佳 免疫抑制方案，其允许AAV再给药以改善功效， 适用SPY-DYS 45 -55。在第二阶段，我们将评估长期功能性益处， 在我们的新研究中，AAV-SPY-DYS 45 -55单次或多次注射的毒性和脱靶活性 含有突变的人DMD基因的小鼠模型。最终，这些研究将产生 将SPY-DYS 45 -55转化为杜氏肌营养不良患者所需的初始临床前数据 营养不良

MyoGene Bio is a startup dedicated to developing cutting edge genetic therapies for muscle diseases. In this proposal, the company will advance development of our potential therapeutic, SPY-DYS45-55, a CRISPR/Cas9 gene editing platform for Duchenne muscular dystrophy (DMD) in conjunction with research partners at UCLA. Duchenne is a devastating muscle wasting disorder with no cure that is caused by out-of-frame mutations in the DMD gene. SPY-DYS45-55 removes a mutational hotspot in DMD to restore the reading frame for half of all Duchenne patients by generating an in-frame exon 45-55 deletion. This deletion is associated with a very mild phenotype in human Becker muscular dystrophy patients. Systemic delivery of gene editing platforms to muscle represents a significant challenge. Certain serotypes of recombinant adenoassociated virus (AAV) have tropism to skeletal muscle and heart. However, the immune response to the virus prohibits repeated administration of AAV. Furthermore, pre-existing immunity in some individuals (anticipated to be present in up to 70% of adults), precludes their eligibility to take advantage of this treatment. The goal of this Fast Track proposal is to devise strategies to overcome these challenges. In Phase I, we will determine an optimal immunosuppression regimen that allows redosing of AAV in order to improve the efficacy and applicability of SPY-DYS45-55. In Phase II, we will assess the long-term functional benefit, toxicity, and off-target activity from single or multiple injections of AAV-SPY-DYS45-55 in our novel mouse model containing a mutated human DMD gene. Ultimately, these studies will generate the initial pre-clinical data needed to translate SPY-DYS45-55 to patients with Duchenne muscular dystrophy.