Several magnetic resonance (MR) biomarkers from the lower extremities, including biomarkers from the proximal muscles, may be predictive of future ambulatory function in patients with Duchenne muscular dystrophy, a study in Neurology reports. These predictive biomarkers include the vastus lateralis fat fraction, soleus fat fraction, vastus lateralis T2 MR imaging (MRI), and biceps femoris long head T2 MRI.

In this longitudinal study, a total of 160 patients with Duchenne muscular dystrophy (mean age, 8.6 years) underwent MR data acquisition of the muscles in the lower extremities. These data informed researchers on participants’ muscle fat fraction and identified T2 MRI biomarkers of disease progression. The 10-minute walk/run test, the 4-stair climb test, the supine-to-stand test, and the 6-minute walk test were performed to examine ambulatory function. Follow-up data collection occurred at 12, 24, 36, and 48 months.

Over time, the fastest progressing biomarkers in the study population were the vastus lateralis fat fraction, vastus lateralis T2 MRI, and biceps femoris long head T2 MRI biomarkers. Biomarkers of the lower extremities were predictive of functional performance 12 and 24 months later. There was an association between the magnitude of 12-month MR biomarker change and likelihood of functional improvement, stability, decline, or loss of ability. The strongest predictors of future loss of function, including the loss of ambulation, were vastus lateralis fat fraction, soleus fat fraction, vastus lateralis T2 MRI, and biceps femoris long head T2 MRI.

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The researchers suggested that a limitation of the study was its small cohort, which reduced their ability to evaluate the sensitivity and progression of MR biomarkers after patients lost ambulation.


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The investigators concluded that these findings exemplify the relationship between MR biomarkers and decline in ambulatory function, including the ability of MR biomarkers to predict future ambulatory function and loss of function. They hope the “inclusion of muscle MR biomarkers will accelerate development and approval of disease-modifying therapeutics for [Duchenne muscular dystrophy].”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Barnard AM, Willcocks RJ, Triplett WT, et al. MR biomarkers predict clinical function in Duchenne muscular dystrophy [published online February 5, 2020]. Neurology. doi:10.1212/WNL.0000000000009012