BACKGROUND Duchenne muscular dystrophy (DMD) is a fatal disease for which no cure is available. Clinical trials have shown to be largely underpowered due to inter-individual variability and noisy outcome measures. The availability of biomarkers able to anticipate clinical benefit is highly needed to improve clinical trial design and facilitate drug development. METHODS In this study, we aimed to appraise the value of protein biomarkers to predict prognosis and monitor disease progression or treatment outcome in patients affected by DMD. We collected clinical data and 303 blood samples from 157 DMD patients in three clinical centres; 78 patients contributed multiple blood samples over time, with a median follow-up time of 2 years. We employed linear mixed models to identify biomarkers that are associated with disease progression, wheelchair dependency, and treatment with corticosteroids and performed survival analysis to find biomarkers whose levels are associated with time to loss of ambulation. RESULTS Our analysis led to the identification of 21 proteins whose levels significantly decrease with age and nine proteins whose levels significantly increase. Seven of these proteins are also differentially expressed in non-ambulant patients, and three proteins are differentially expressed in patients treated with glucocorticosteroids. Treatment with corticosteroids was found to partly counteract the effect of disease progression on two biomarkers, namely, malate dehydrogenase 2 (MDH2, P = 0.0003) and ankyrin repeat domain 2 (P = 0.0005); however, patients treated with corticosteroids experienced a further reduction on collagen 1 serum levels (P = 0.0003), especially following administration of deflazacort. A time to event analysis allowed to further support the use of MDH2 as a prognostic biomarker as it was associated with an increased risk of wheelchair dependence (P = 0.0003). The obtained data support the prospective evaluation of the identified biomarkers in natural history and clinical trials as exploratory biomarkers. CONCLUSIONS We identified a number of serum biomarkers associated with disease progression, loss of ambulation, and treatment with corticosteroids. The identified biomarkers are promising candidate prognostic and surrogate biomarkers, which may support drug developers if confirmed in prospective studies. The serum levels of MDH2 are of particular interest, as they correlate with disease stage and response to treatment with corticosteroids, and are also associated with the risk of wheelchair dependency and pulmonary function.

中文翻译：

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纵向血清生物标志物筛选将苹果酸脱氢酶2鉴定为Duchenne肌营养不良症的候选预后生物标志物。

背景技术杜兴氏肌营养不良症（DMD）是一种致命疾病，无法治愈。由于个体间的变异性和嘈杂的结局指标，临床试验显示出其功能不足。为了改善临床试验设计和促进药物开发，迫切需要能够预见临床益处的生物标志物。方法在本研究中，我们旨在评估蛋白质生物标志物的价值，以预测受DMD影响的患者的预后并监测疾病的进展或治疗结果。我们从三个临床中心的157名DMD患者中收集了临床数据和303份血液样本；78名患者随时间提供了多个血液样本，中位随访时间为2年。我们采用线性混合模型来识别与疾病进展相关的生物标志物，轮椅依赖性，以及皮质类固醇激素治疗，并进行生存分析，以寻找其生物标志物水平与失步时间相关的生物标志物。结果我们的分析导致鉴定出21种蛋白质的水平随着年龄的增长而显着下降，而9种蛋白质的水平随着年龄的增长而显着增加。在非卧床患者中，这些蛋白质中的七个也有差异表达，而在糖皮质激素治疗的患者中，三个蛋白质也有差异表达。发现用皮质类固醇激素治疗可以部分抵消疾病进展对两种生物标记物的影响，这两种生物标记物是苹果酸脱氢酶2（MDH2，P = 0.0003）和锚蛋白重复结构域2（P = 0.0005）。但是，接受皮质类固醇激素治疗的患者的胶原蛋白1血清水平进一步降低（P = 0.0003），尤其是在服用了deflazacort之后。事件发生时间分析可进一步支持将MDH2用作预后生物标志物，因为它与轮椅依赖风险增加相关（P = 0.0003）。获得的数据支持对自然历史和临床试验中鉴定的生物标志物进行探索性生物标志物的前瞻性评估。结论我们确定了许多与疾病进展，活动能力下降和皮质类固醇激素治疗相关的血清生物标志物。鉴定出的生物标志物是有希望的预后和替代生物标志物，如果在前瞻性研究中得到证实，则可能会支持药物开发者。MDH2的血清水平特别令人关注，因为它们与疾病分期和对皮质类固醇激素治疗的反应相关，