Preclinic dose and delivery regime optimization and long-term efficacy evaluation of ribitol treatment for FKRP related dystroglycanopathy

项目主任/首席调查员(最后、第一、中间)：吕齐 项目摘要 FKRP基因突变导致肌营养不良症，严重程度差异很大，具有 -DG糖基化缺陷的生化特征。这种疾病的进行性导致了一种 肌肉纤维的持续丢失和纤维化的增加，最后是肌肉功能的丧失，最终 呼吸和心脏功能衰竭，导致过早死亡。目前还没有可用的治疗方法 尽管有几种实验性疗法正在动物模型中进行测试。 最近，以CDP-核糖醇为底物，FKRP被鉴定为核糖醇-5-磷酸转移酶。 层粘连蛋白结合双聚糖(Matriglycan)在-DG上延伸的底物，是肌肉的关键步骤 正直。早期的研究表明，补充核糖醇可以导致细胞内CDP-核糖醇水平的增加。我们 最近也证明了突变的FKRPs保留了足够的功能来糖基化-DG 以突变型P448L FKRP为转基因载体的基因治疗。我们现在已经证明了 在我们的临床相关的P448L突变小鼠模型中，补充核糖醇增加了Matriglycan的水平， 从而显著改善心肌和骨骼肌的肌肉病理和功能。 这为大多数FKRP肌肉的治疗开辟了一种新的、高度特异性和临床适用的方法。 营养不良。 在这项建议中，我们将首先优化核糖醇在fkrp p448L突变体中的剂量和给药方案。 通过测试灌胃给药和饮用水两种途径的一系列剂量，建立小鼠模型。这个 疗效将通过功能性糖基化水平和营养不良病理的改善来评估。我们会 然后检查所选剂量和给药方案的长期疗效(12个月)和安全性 三株FKRP突变小鼠P448L、L276I纯合子和P448L/L276I复合体 90%以上患者携带临床相关突变并代表疾病的杂合子 从轻度到重度营养不良表型。这些突变株已在麦考尔 洛克伍德实验室。其目的是建立至少一种具有长期疗效的剂量和给药制度 临床试验的进一步发展。 这项建议的目标是建立一个实际可交付的剂量和治疗制度，长期- IND应用于临床相关小鼠模型的长期疗效。 PHS 398/2590(06/09版)页面续格式页面

Program Director/Principal Investigator (Last, First, Middle): Lu Qi Long Project Summary Mutations in FKRP gene cause muscular dystrophy with wide variation in severity with characteristic biochemical feature of defect in glycosylation of -DG. The progressive nature of the disease leads to a continuous loss of muscle fibers and increase in fibrosis, and finally loss of muscle function and ultimately failure of respiratory and cardiac functions, leading to early death. Currently no treatment is available although several experimental therapies are being tested in animal models. Recently, FKRP has been identified as a ribitol-5-phosphate transferase using CDP-ribitol as the substrate for the extension of the laminin binding biglycan (matriglycan) on -DG, a critical step for muscle integrity. Earlier study suggests that ribitol supplement can lead to an increase of CDP-ribitol levels in cells. We also demonstrated recently that mutant FKRPs retain sufficient levels of function to glycosylate -DG by AAV mediated gene therapy with mutant P448L FKRP as the transgene. We have now demonstrated that supplement of ribitol increases levels of matriglycan in our clinically relevant P448L mutant mouse model, resulting in significant improvement in muscle pathology and functions in both cardiac and skeletal muscles. This opens a novel, highly specific and clinically applicable means to treat the majority of FKRP muscular dystrophy. In this proposal, we will first optimize dosage and administration regime of ribitol in fkrp P448L mutant mouse model by testing a range of doses with both routes of gavage administration and in drinking water. The effects will be evaluated by levels of functional glycosylation and improvement of dystrophic pathology. We will then examine long-term efficacy (12 months) and safety of the selected dosing and delivery regime of ribitol in three strains of FKRP mutant mice, P448L, L276I homozygote, and P448L/L276I compound heterozygotes bearing clinically relevant mutations in more than 90% patients and representing diseases from mild to severe dystrophic phenotypes. These mutant strains have been established in the McColl Lockwood Laboratory. The aim is to establish at least one dose and delivery regime with long-term efficacy for further development towards clinic trials. The goal of this proposal is to establish a practically deliverable dosing and treatment regime with long- term therapeutic efficacy in clinically relevant mouse models for IND application. PHS 398/2590 (Rev. 06/09) Page Continuation Format Page