Degan Chiara, Tsonaka Roula, de Vries Sharon I, Ikelaar Nadine, van der Holst Menno, Kan Hermien E, Niks Erik H, Spitali Pietro
Department of Biomedical Data Sciences, Leiden University Medical Center, The Netherlands.
Department of Human Genetics, Leiden University Medical Center, The Netherlands.
medRxiv. 2025 Aug 14:2025.08.11.25333307. doi: 10.1101/2025.08.11.25333307.
Duchenne Muscular Dystrophy (DMD) is characterized by progressive muscle wasting leading to early loss of motor function. Functional tests monitor disease progression and serve as clinical trial endpoints, but are influenced by maturation in younger patients, variability, and patient motivation. Blood biomarkers, that can predict disease progression and objectively evaluate treatment responses, offer a valuable alternative.In this study, we investigated whether longitudinal observations of biomarkers myostatin and the creatine/creatinine ratio (Cr/Crn) are associated with functional tests, such as 6-minute walk test, North Star Ambulatory Assessment (NSAA), 10-meter walk-run test velocity, Performance of Upper Limb (PUL2.0), and disease milestones like loss of ambulation (LoA), overhead reach. and hand-to-mouth function.
We used real-world longitudinal data from 74 DMD patients followed for up to 11 years with annual visits to the LUMC outpatient clinic, linked to 408 serum samples. Associations between biomarkers, functional tests, and clinical milestones were assessed using linear mixed models and time-dependent Cox models, respectively.
Lower Cr/Crn levels and higher myostatin levels were associated with better functional performance and a less rapid decline in ambulation, given fixed treatment and BMI. Children with one-unit higher log2-myostatin levels had, on average, 4.73 points higher NSAA and 3.40 points higher PUL2.0 (both p < 0.001), and were 42% less likely to lose ambulation over the following year. Conversely, children with one-unit lower log2-ratio levels had, on average, 7.18 points higher NSAA and 11.40 points higher PUL2.0 (both p < 0.001), and were 3.67 times more likely to remain ambulant. We also proved that incorporating log2-myostatin and log2-Cr/Crn as endpoints could reduce the required sample size for clinical trials by more than half without compromising statistical power. For instance, to detect a yearly drop of 3 points in the NSAA with 80% power, recruitment requires almost 80 participants in a 1:1 randomized trial, in contrast to a little more than 50 patients for the respective value of log2-myostatin or log2-Cr/Crn.
These findings support the potential of myostatin and Cr/Crn as prognostic biomarkers to enhance trial design and endpoint in clinical and interventional trials for DMD.
杜氏肌营养不良症（DMD）的特征是进行性肌肉萎缩，导致运动功能早期丧失。功能测试可监测疾病进展并作为临床试验终点，但受年轻患者成熟度、变异性和患者积极性的影响。能够预测疾病进展并客观评估治疗反应的血液生物标志物提供了一种有价值的替代方法。在本研究中，我们调查了肌肉生长抑制素和肌酸/肌酐比值（Cr/Crn）等生物标志物的纵向观察结果是否与功能测试相关，如6分钟步行测试、北极星动态评估（NSAA）、10米步行-跑步测试速度、上肢功能测试（PUL2.0），以及与疾病里程碑事件如失去行走能力（LoA）、上肢伸展和手到嘴功能的关系。
我们使用了来自74名DMD患者的真实世界纵向数据，这些患者在鹿特丹大学医学中心门诊随访长达11年，每年就诊一次，并与408份血清样本相关联。分别使用线性混合模型和时间依赖性Cox模型评估生物标志物、功能测试和临床里程碑之间的关联。
在固定治疗和体重指数的情况下，较低的Cr/Crn水平和较高的肌肉生长抑制素水平与更好的功能表现以及行走能力下降较慢相关。log2-肌肉生长抑制素水平每升高一个单位的儿童，平均NSAA得分高4.73分，PUL2.0得分高3.40分（均p<0.001），且在接下来的一年中失去行走能力的可能性降低42%。相反，log2-比值水平每降低一个单位的儿童，平均NSAA得分高7.18分，PUL2.0得分高11.40分（均p<0.001），且保持行走能力的可能性高3.67倍。我们还证明，将log2-肌肉生长抑制素和log2-Cr/Crn作为终点可以将临床试验所需的样本量减少一半以上，而不影响统计效力。例如，要在80%的效力下检测到NSAA每年下降3分，在1:1随机试验中招募需要近80名参与者，相比之下，对于log2-肌肉生长抑制素或log2-Cr/Crn的相应值，只需略多于50名患者。
这些发现支持了肌肉生长抑制素和Cr/Crn作为预后生物标志物在DMD临床和干预试验中加强试验设计和终点的潜力。
