McColl-Lockwood Laboratory for Muscular Dystrophy Research, Neuromuscular/ALS Center, Department of Neurology, Carolinas Medical Center, Charlotte, North Carolina, USA.
Am J Pathol. 2012 Aug;181(2):392-400. doi: 10.1016/j.ajpath.2012.04.006. Epub 2012 Jun 7.
Exon skipping is capable of correcting frameshift and nonsense mutations in Duchenne muscular dystrophy. Phase 2 clinical trials in the United Kingdom and the Netherlands have reported induction of dystrophin expression in muscle of Duchenne muscular dystrophy patients by systemic administration of both phosphorodiamidate morpholino oligomers (PMO) and 2'-O-methyl phosphorothioate. Peptide-conjugated phosphorodiamidate morpholino offers significantly higher efficiency than phosphorodiamidate morpholino, with the ability to induce near-normal levels of dystrophin, and restores function in both skeletal and cardiac muscle. We examined 1-year systemic efficacy of peptide-conjugated phosphorodiamidate morpholino targeting exon 23 in dystrophic mdx mice. The LD(50) of peptide-conjugated phosphorodiamidate morpholino was determined to be approximately 85 mg/kg. The half-life of dystrophin expression was approximately 2 months in skeletal muscle, but shorter in cardiac muscle. Biweekly injection of 6 mg/kg peptide-conjugated phosphorodiamidate morpholino produced >20% dystrophin expression in all skeletal muscles and ≤5% in cardiac muscle, with improvement in muscle function and pathology and reduction in levels of serum creatine kinase. Monthly injections of 30 mg/kg peptide-conjugated phosphorodiamidate morpholino restored dystrophin to >50% normal levels in skeletal muscle, and 15% in cardiac muscle. This was associated with greatly reduced serum creatine kinase levels, near-normal histology, and functional improvement of skeletal muscle. Our results demonstrate for the first time that regular 1-year administration of peptide-conjugated phosphorodiamidate morpholino can be safely applied to achieve significant therapeutic effects in an animal model.
外显子跳跃能够纠正杜氏肌营养不良症中的移码和无义突变。英国和荷兰的 2 期临床试验报告称，通过系统给予磷酸二酰胺吗啉寡聚物（PMO）和 2'-O-甲基硫代磷酸酯，可在杜氏肌营养不良症患者的肌肉中诱导肌营养不良蛋白的表达。肽偶联的磷酸二酰胺吗啉的效率明显高于磷酸二酰胺吗啉，能够诱导接近正常水平的肌营养不良蛋白，并恢复骨骼肌和心肌的功能。我们研究了靶向外显子 23 的肽偶联的磷酸二酰胺吗啉在肌营养不良症 mdx 小鼠中的 1 年系统疗效。肽偶联的磷酸二酰胺吗啉的 LD(50)约为 85mg/kg。肌营养不良蛋白表达的半衰期在骨骼肌中约为 2 个月，但在心肌中较短。每周两次注射 6mg/kg 的肽偶联的磷酸二酰胺吗啉可使所有骨骼肌中的肌营养不良蛋白表达超过 20%，而心肌中的肌营养不良蛋白表达≤5%，同时改善肌肉功能和病理学，并降低血清肌酸激酶水平。每月注射 30mg/kg 的肽偶联的磷酸二酰胺吗啉可使骨骼肌中的肌营养不良蛋白恢复到正常水平的 50%以上，心肌中的肌营养不良蛋白恢复到 15%。这与血清肌酸激酶水平的大幅降低、接近正常的组织学和骨骼肌功能的改善密切相关。我们的结果首次表明，定期 1 年给予肽偶联的磷酸二酰胺吗啉可以安全应用于动物模型，以实现显著的治疗效果。
