Mendell Jerry R, Rodino-Klapac Louise R, Rosales-Quintero Xiomara, Kota Janaiah, Coley Brian D, Galloway Gloria, Craenen Josepha M, Lewis Sarah, Malik Vinod, Shilling Christopher, Byrne Barry J, Conlon Thomas, Campbell Katherine J, Bremer William G, Viollet Laurence, Walker Christopher M, Sahenk Zarife, Clark K Reed
Department of Pediatrics, Ohio State University, Columbus, OH, USA.
Ann Neurol. 2009 Sep;66(3):290-7. doi: 10.1002/ana.21732.
alpha-Sarcoglycan deficiency results in a severe form of muscular dystrophy (limb-girdle muscular dystrophy type 2D [LGMD2D]) without treatment. Gene replacement represents a strategy for correcting the underlying defect. Questions related to this approach were addressed in this clinical trial, particularly the need for immunotherapy and persistence of gene expression.
A double-blind, randomized controlled trial using rAAV1.tMCK.hSGCA injected into the extensor digitorum brevis muscle was conducted. Control sides received saline. A 3-day course of methylprednisolone accompanied gene transfer without further immune suppression.
No adverse events were encountered. SGCA gene expression increased 4-5-fold over control sides when examined at 6 weeks (2 subjects) and 3 months (1 subject). The full sarcoglycan complex was restored in all subjects, and muscle fiber size was increased in the 3-month subject. Adeno-associated virus serotype 1 (AAV1)-neutralizing antibodies were seen as early as 2 weeks. Neither CD4+ nor CD8+ cells were increased over contralateral sides. Scattered foci of inflammation could be found, but showed features of programmed cell death. Enzyme-linked immunospot (ELISpot) showed no interferon-gamma response to alpha-SG or AAV1 capsid peptide pools, with the exception of a minimal capsid response in 1 subject. Restimulation to detect low-frequency capsid-specific T cells by ELISpot assays was negative. Results of the first 3 subjects successfully achieved study aims, precluding the need for additional enrollment.
The finding of this gene replacement study in LGMD2D has important implications for muscular dystrophy. Sustained gene expression was seen, but studies over longer time periods without immunotherapy will be required for design of vascular delivery gene therapy trials.
α-肌聚糖缺乏会导致一种严重的肌肉萎缩症（2D型肢带型肌营养不良症[LGMD2D]），且无有效治疗方法。基因替代是一种纠正潜在缺陷的策略。本临床试验探讨了与该方法相关的问题，特别是免疫治疗的必要性和基因表达的持续性。
进行了一项双盲、随机对照试验，将rAAV1.tMCK.hSGCA注射到趾短伸肌中。对照侧注射生理盐水。基因转移时给予为期3天的甲泼尼龙疗程，无需进一步免疫抑制。
未出现不良事件。在6周（2名受试者）和3个月（1名受试者）时检查发现，SGCA基因表达比对照侧增加了4 - 5倍。所有受试者的完整肌聚糖复合物均得以恢复，3个月时的受试者肌肉纤维大小增加。腺相关病毒1型（AAV1）中和抗体最早在2周时出现。与对侧相比，CD4 +和CD8 +细胞均未增加。可发现散在的炎症病灶，但表现为程序性细胞死亡特征。酶联免疫斑点试验（ELISpot）显示，除1名受试者对衣壳有轻微反应外，对α-SG或AAV1衣壳肽库均无干扰素-γ反应。通过ELISpot试验重新刺激以检测低频衣壳特异性T细胞结果为阴性。前3名受试者的结果成功达到研究目的，无需额外入组。
LGMD2D基因替代研究的这一发现对肌肉萎缩症具有重要意义。观察到基因表达持续存在，但血管内递送基因治疗试验的设计需要更长时间且无免疫治疗的研究。
