Department of Paediatrics, University of Oxford, Oxford, UK.
Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
RNA Biol. 2021 Jul;18(7):1048-1062. doi: 10.1080/15476286.2021.1874161. Epub 2021 Jan 20.
Duchenne muscular dystrophy (DMD) is a currently incurable X-linked neuromuscular disorder, characterized by progressive muscle wasting and premature death, typically as a consequence of cardiac failure. DMD-causing mutations in the dystrophin gene are highly diverse, meaning that the development of a universally-applicable therapy to treat all patients is very challenging. The leading therapeutic strategy for DMD is antisense oligonucleotide-mediated splice modulation, whereby one or more specific exons are excluded from the mature dystrophin mRNA in order to correct the translation reading frame. Indeed, three exon skipping oligonucleotides have received FDA approval for use in DMD patients. Second-generation exon skipping drugs (i.e. peptide-antisense oligonucleotide conjugates) exhibit enhanced potency, and also induce dystrophin restoration in the heart. Similarly, multiple additional antisense oligonucleotide drugs targeting various exons are in clinical development in order to treat a greater proportion of DMD patient mutations. Relatively recent advances in the field of genome engineering (specifically, the development of the CRISPR/Cas system) have provided multiple promising therapeutic approaches for the RNA-directed genetic correction of DMD, including exon excision, exon reframing via the introduction of insertion/deletion mutations, disruption of splice signals to promote exon skipping, and the templated correction of point mutations by seamless homology directed repair or base editing technology. Potential limitations to the clinical translation of the splice modulation and gene editing approaches are discussed, including drug delivery, the importance of uniform dystrophin expression in corrected myofibres, safety issues (e.g. renal toxicity, viral vector immunogenicity, and off-target gene editing), and the high cost of therapy.
杜氏肌营养不良症(DMD)是一种目前无法治愈的 X 连锁神经肌肉疾病,其特征是进行性肌肉萎缩和过早死亡,通常是心力衰竭的结果。导致肌营养不良蛋白基因突变的 DMD 非常多样化,这意味着开发一种普遍适用于所有患者的治疗方法极具挑战性。DMD 的主要治疗策略是反义寡核苷酸介导的剪接调节,通过该策略可以从成熟的肌营养不良蛋白 mRNA 中排除一个或多个特定外显子,从而纠正翻译阅读框。事实上,已有三种外显子跳跃寡核苷酸获得 FDA 批准用于 DMD 患者。第二代外显子跳跃药物(即肽-反义寡核苷酸缀合物)具有更高的效力,并且还可以在心脏中诱导肌营养不良蛋白的恢复。同样,为了治疗更大比例的 DMD 患者突变,还有多种针对各种外显子的额外反义寡核苷酸药物正在临床开发中。基因组工程领域的相对较新进展(具体来说,是 CRISPR/Cas 系统的发展)为 DMD 的 RNA 导向遗传纠正提供了多种有前途的治疗方法,包括外显子切除、通过插入/缺失突变引入外显子重排、破坏剪接信号以促进外显子跳跃,以及通过无缝同源定向修复或碱基编辑技术模板化纠正点突变。讨论了剪接调节和基因编辑方法在临床转化中的潜在局限性,包括药物输送、纠正肌纤维中均匀肌营养不良蛋白表达的重要性、安全性问题(例如肾毒性、病毒载体免疫原性和脱靶基因编辑)以及治疗的高成本。