Antisense therapy for DMD-Optimization and toxicology of AON for exon 45 skipping

描述（由申请人提供）：杜氏肌营养不良症（DMD）是最常见的肌营养不良形式，每3500个活产男婴中就有1个患有此病。该病的特点是严重的肌肉萎缩和无力，临床上在3至5岁之间变得明显。DMD是由肌营养不良蛋白基因中所谓的帧移位突变引起的，导致过早终止，没有蛋白质合成，而BMD是由突变引起的，它产生截断的，但帧内转录本具有部分或几乎全部功能的蛋白质。反义寡核苷酸（AON）介导的外显子剪接（反义疗法）已被证明可有效地恢复由导致DMD的突变破坏的开放阅读框。P.I.项目已经证实，在毒性可耐受的动物模型中，通过定期给药肽标记的morpholino AON (PPMO)，可以恢复和维持接近正常水平的肌营养不良蛋白。我们还解决了几个重要的问题，关键的治疗成功应用于临床。可靠的AON体外选择系统的发展使我们能够建立高效的AON作为靶向单个外显子的特异性药物。我们已经确定了给药方案，以便在临床试验中以最小的毒性达到治疗效果。在这个项目中，我们的目标是将成功的实验疗法转化为DMD的临床治疗。实验计划以实现明确的里程碑为中心：1)选择最有效的靶向人肌营养不良蛋白45外显子的AON，去除该AON可治疗大部分DMD患者。这一目标将通过建立细胞培养系统来实现。2)确定所选PPMOs在动物模型中的功效以及所选PPMOs在细胞培养中的脱靶效应。3)进行毒理学测试，从而向FDA提交研究性新药申请。反义疗法对DMD动物模型的治疗是有效的，为治疗大多数DMD提供了现实的希望。我们的目标是将这种疗法转化为临床试验。

DESCRIPTION (provided by applicant): Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy affecting 1 in every 3500 live male births. The disease is characterized by severe muscle wasting and weakness, which becomes clinically evident between the ages of 3 to 5 years. DMD is caused by so called frame-shift mutations in the dystrophin gene leading to premature termination with no protein synthesis whereas BMD is caused by mutations which create truncated, but in-frame transcripts with proteins of partial or nearly full function. Antisense oligonucleotide (AON)-mediated exon splicing (antisense therapy) has been shown to be effective for restoration of the open reading frame disrupted by mutations that cause DMD. The project P.I. has established the facts that near normal levels of dystrophin can be restored and maintained in the body-wide skeletal muscles through regular administration of a peptide-tagged morpholino AON (PPMO) in animal models with tolerable 7 toxicity. We have also addressed several important issues critical for successful applications of the therapy to clinics. The development of a reliable in vitro system for AON selection enables us to establish highly effective AONs as specific drugs to target individual exons. We have defined the regimen of administration so therapeutic effect can be achieved with minimum toxicity for clinical trial. In this project/we aim to translate the successful experimental therapy to clinical treatment of DMD. The experimental plan is centered to achieve well-defined milestones: 1) Select most efficacious AON for targeting human dystrophin exon 45, the removal of which can treat a large proportion of DMD patients. This aim will be achieved with established cell culture systems. 2) Determine the efficacy of selected PPMOs in animal models and off-target effects of the selected PPMOs in cell cultures. 3) Conduct toxicology tests, thus an investigational new drug application can be submitted to the FDA. Antisense therapy is effective in treating animal models of DMD and provides a realistic hope for treating the majority of DMD. We aim to translate the therapy into clinical trials. PUBLIC HEALTH RELEVANCE: Duchenne muscular dystrophy (DMD) is a common and fatal genetic disease and there is no cure currently. Antisense therapy aims to rescue the functions of diseased muscles and provides a realistic hope for treating the majority of DMD.