Duchenne muscular dystrophy (DMD) is a rare, X-linked, fatal, degenerative neuromuscular disease caused by mutations in the DMD gene. More than 2,000 mutations of the DMD gene are responsible for progressive loss of muscle strength, loss of ambulation, and generally respiratory and cardiac failure by age 30. Recently, gene transfer therapy has received widespread interest as a disease-modifying treatment for all patients with DMD. We designed an adeno-associated virus vector (rAAVrh74) containing a codon-optimized human micro-dystrophin transgene driven by a skeletal and cardiac muscle-specific promoter, MHCK7. To test the efficacy of rAAVrh74.MHCK7.micro-dystrophin, we evaluated systemic injections in mdx (dystrophin-null) mice at low (2 × 10¹² vector genome [vg] total dose, 8 × 10¹³ vg/kg), intermediate (6 × 10¹² vg total dose, 2 × 10¹⁴ vg/kg), and high doses (1.2 × 10¹³ vg total dose, 6 × 10¹⁴ vg/kg). Three months posttreatment, specific force increased in the diaphragm (DIA) and tibialis anterior muscle, with intermediate and high doses eliciting force outputs at wild-type (WT) levels. Histological improvement included reductions in fibrosis and normalization of myofiber size, specifically in the DIA, where results for low and intermediate doses were not significantly different from the WT. Significant reduction in central nucleation was also observed, although complete normalization to WT was not seen. No vector-associated toxicity was reported either by clinical or organ-specific laboratory assessments or following formal histopathology. The findings in this preclinical study provided proof of principle for safety and efficacy of systemic delivery of rAAVrh74.MHCK7.micro-dystrophin at high vector titers, supporting initiation of a Phase I/II safety study in boys with DMD.

中文翻译：

---

在杜氏肌营养不良 mdx 小鼠模型中系统性递送 rAAVrh74.MHCK7.micro-dystrophin 的剂量递增研究

杜氏肌营养不良症 (DMD) 是一种罕见的 X 连锁致死性退行性神经肌肉疾病，由DMD基因突变引起。到 30 岁时， DMD基因的2,000 多个突变导致肌肉力量进行性丧失、不能行走，以及一般的呼吸和心力衰竭。最近，基因转移疗法作为一种改善所有患有以下疾病的患者的疾病治疗方法受到了广泛关注。 DMD。我们设计了一种腺相关病毒载体 (rAAVrh74)，其中包含由骨骼和心肌特异性启动子 MHCK7 驱动的密码子优化的人类微肌营养不良蛋白转基因。为了测试 rAAVrh74.MHCK7.micro-dystrophin 的功效，我们在低 (2 × 10 ¹²载体基因组 [vg] 总剂量，8 × 10 ¹³ vg/kg），中剂量（6 × 10 ¹² vg 总剂量，2 × 10 ¹⁴ vg/kg）和高剂量（1.2 × 10 ¹³ vg 总剂量，6 × 10 ¹⁴克/公斤）。治疗三个月后，膈肌 (DIA) 和胫骨前肌的比力增加，中等和高剂量在野生型 (WT) 水平上引起力输出。组织学改善包括纤维化减少和肌纤维大小正常化，特别是在 DIA，低和中剂量的结果与 WT 没有显着差异。还观察到中心成核显着减少，尽管未观察到对 WT 的完全标准化。临床或器官特异性实验室评估或正式组织病理学报告均未报告载体相关毒性。这项临床前研究的结果为高载体滴度的 rAAVrh74.MHCK7.micro-dystrophin 全身递送的安全性和有效性提供了原理证明，