Quantitative magnetic resonance imaging measures as biomarkers of disease progression in boys with Duchenne muscular dystrophy: a phase 2 trial of domagrozumab

Muscle MRI as a biomarker of disease activity and progression in myotonic dystrophy type 1: a longitudinal study

INTRODUCTION

Myotonic dystrophy type 1 (DM1) is an autosomal dominant disease characterized by myotonia and progressive muscular weakness and atrophy. The aim of this study was to investigate the usefulness of longitudinal muscle MRI in detecting disease activity and progression in DM1, and to better characterize muscle edema, fat replacement and atrophy overtime.

MATERIALS AND METHODS

This is a prospective, observational, longitudinal study including 25 DM1 patients that performed at least two muscle MRIs. Demographic and genetic characteristics were recorded. Muscular Impairment Rating Scale (MIRS) and MRC score were performed within 3 months from MRIs at baseline (BL) and at follow-up (FU). We analysed 32 muscles of lower body (LB) and 17 muscles of upper body (UB) by T1 and STIR sequences. T1-, STIR- and atrophy scores and their variations were evaluated. Correlations between MRIs' scores and demographic, clinical and genetic characteristics were analysed.

RESULTS

Eighty (80%) of patients showed fat replacement progression at FU. The median T1 score progression (ΔT1-score) was 1.3% per year in LB and 0.5% per year in UB. The rate of fat replacement progression was not homogenous, stratifying patients from non-progressors to fast progressors (> 3% ΔT1-score per year). Half of the STIR-positive muscles at BL showed T1-score progression at FU. Two patients with normal MRI at baseline only showed STIR-positive muscle at FU, marking the disease activity onset. STIR positivity at baseline correlated with fat replacement progression (ΔT1-score; p < 0.0001) and clinical worsening at FU (ΔMRC-score; p < 0.0001). Sixty-five (65%) of patients showed STIR- and fat replacement-independent muscle atrophy progression, more evident in UB.

CONCLUSIONS

Muscle MRI represents a sensitive biomarker of disease activity, severity, and progression in DM1. STIR alterations precede fat replacement and identify patients with a higher risk of disease progression, while T1-sequences reveal atrophy and fat replacement progression before clinical worsening.

Single-Nucleus RNA Sequencing Unravels Early Mechanisms of Human Becker Muscular Dystrophy

OBJECTIVE

The transcriptional heterogeneity at a single-nucleus level in human Becker muscular dystrophy (BMD) dystrophic muscle has not been explored. Here, we aimed to understand the transcriptional heterogeneity associated with myonuclei, as well as other mononucleated cell types that underly BMD pathogenesis by performing single-nucleus RNA sequencing.

METHODS

We profiled single-nucleus transcriptional profiles of skeletal muscle samples from 7 BMD patients and 3 normal controls.

RESULTS

A total of 17,216 nuclei (12,879 from BMD patients and 4,337 from controls) were classified into 13 known cell types, including 9 myogenic lineages and 4 non-myogenic lineages, and 1 unclassified nuclear type according to their cell identities. Among them, type IIx myonuclei were the first to degenerate in response to dystrophin reduction. Differential expression analysis revealed that the fibro-adipogenic progenitors (FAPs) population had the largest transcriptional changes among all cell types. Sub-clustering analysis identified a significantly compositional increase in the activated FAPs (aFAPs) subpopulation in BMD muscles. Pseudotime analysis, regulon inference, and deconvolution analysis of bulk RNA-sequencing data derived from 29 BMD patients revealed that the aFAPs subpopulation, a distinctive and previously unrecognized mononuclear subtype, was profibrogenic and expanded in BMD patients. Muscle quantitative real-time polymerase chain reaction and immunofluorescence analysis confirmed that the mRNA and protein levels of the aFAPs markers including LUM, DCN, and COL1A1 in BMD patients were significantly higher than those in controls, respectively.

INTERPRETATION

Our results provide insights into the transcriptional diversity of human BMD muscle at a single-nucleus resolution and new potential targets for anti-fibrosis therapies in BMD. ANN NEUROL 2024.

Value of radiomics-based automatic grading of muscle edema in polymyositis/dermatomyositis based on MRI fat-suppressed T2-weighted images

BACKGROUND

The precise and objective assessment of thigh muscle edema is pivotal in diagnosing and monitoring the treatment of dermatomyositis (DM) and polymyositis (PM).

PURPOSE

Radiomic features are extracted from fat-suppressed (FS) T2-weighted (T2W) magnetic resonance imaging (MRI) of thigh muscles to enable automatic grading of muscle edema in cases of polymyositis and dermatomyositis.

MATERIAL AND METHODS

A total of 241 MR images were analyzed and classified into five levels using the Stramare criteria. The correlation between muscle edema grading and T2-mapping values was assessed using Spearman's correlation. The dataset was divided into a 7:3 ratio of training (168 samples) and testing (73 samples). Thigh muscle boundaries in FS T2W images were manually delineated with 3D-Slicer. Radiomics features were extracted using Python 3.7, applying Z-score normalization, Pearson correlation analysis, and recursive feature elimination for reduction. A Naive Bayes classifier was trained, and diagnostic performance was evaluated using receiver operating characteristic (ROC) curves and comparing sensitivity and specificity with senior doctors.

RESULTS

A total of 1198 radiomics parameters were extracted and reduced to 18 features for Naive Bayes modeling. In the testing set, the model achieved an area under the ROC curve of 0.97, sensitivity of 0.85, specificity of 0.98, and accuracy of 0.91. The Naive Bayes classifier demonstrated grading performance comparable to senior doctors. A significant correlation (r = 0.82, P <0.05) was observed between Stramare edema grading and T2-mapping values.

CONCLUSION

The Naive Bayes model, utilizing radiomics features extracted from thigh FS T2W images, accurately assesses the severity of muscle edema in cases of PM/DM.

Evaluation of Neuromuscular Diseases and Complaints by Quantitative Muscle MRI

Background: Quantitative muscle MRI (qMRI) is a promising tool for evaluating and monitoring neuromuscular disorders (NMD). However, the application of different imaging protocols and processing pipelines restricts comparison between patient cohorts and disorders. In this qMRI study, we aim to compare dystrophic (limb-girdle muscular dystrophy), inflammatory (inclusion body myositis), and metabolic myopathy (Pompe disease) as well as patients with post-COVID-19 conditions suffering from myalgia to healthy controls. Methods: Ten subjects of each group underwent a 3T lower extremity muscle MRI, including a multi-echo, gradient-echo, Dixon-based sequence, a multi-echo, spin-echo (MESE) T2 mapping sequence, and a spin-echo EPI diffusion-weighted sequence. Furthermore, the following clinical assessments were performed: Quick Motor Function Measure, patient questionnaires for daily life activities, and 6-min walking distance. Results: Different involvement patterns of conspicuous qMRI parameters for different NMDs were observed. qMRI metrics correlated significantly with clinical assessments. Conclusions: qMRI metrics are suitable for evaluating patients with NMD since they show differences in muscular involvement in different NMDs and correlate with clinical assessments. Still, standardisation of acquisition and processing is needed for broad clinical use.

A novel biomarker of fibrofatty replacement in dystrophinopathies identified by integrating transcriptome, magnetic resonance imaging, and pathology data

BACKGROUND

We aimed to analyse genome-wide transcriptome differences between Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) patients and identify biomarkers that correlate well with muscle magnetic resonance imaging (MRI) and histological fibrofatty replacement in both patients, which have not been reported.

METHODS

One hundred and one male patients with dystrophinopathies (55 DMD and 46 BMD) were enrolled. Muscle-derived genome-wide RNA-sequencing was performed in 31 DMD patients, 29 BMD patients, and 11 normal controls. Fibrofatty replacement was scored on muscle MRI and histological levels in all patients. A unique pipeline, single-sample gene set enrichment analysis combined with Spearman's rank correlations (ssGSEA-Cor) was developed to identify the most correlated gene signature for fibrofatty replacement. Quantitative real-time PCR (qRT-PCR) analysis, western blot analysis, and single-nucleus RNA-sequencing (snRNA-seq) were performed in the remaining patients to validate the most correlated gene signature.

RESULTS

Comparative transcriptomic analysis revealed that 31 DMD muscles were characterized by a significant increase of inflammation/immune response and extracellular matrix remodelling compared with 29 BMD muscles (P < 0.05). The ssGSEA-Cor pipeline revealed that the gene set of CDKN2A and CDKN2B was the most correlated gene signature for fibrofatty replacement (histological rs  = 0.744, P < 0.001; MRI rs  = 0.718, P < 0.001). Muscle qRT-PCR confirmed that CDKN2A mRNA expression in both 15 DMD (median = 25.007, P < 0.001) and 12 BMD (median = 5.654, P < 0.001) patients were significantly higher than that in controls (median = 1.101), while no significant difference in CDKN2B mRNA expression was found among DMD, BMD, and control groups. In the 27 patients, muscle CDKN2A mRNA expression respectively correlated with muscle MRI (rs  = 0.883, P < 0.001) and histological fibrofatty replacement (rs  = 0.804, P < 0.001) and disease duration (rs  = 0.645, P < 0.001) and North Star Ambulatory Assessment total scores (rs  = -0.698, P < 0.001). Muscle western blot analysis confirmed that both four DMD (median = 2.958, P < 0.05) and four BMD (median = 1.959, P < 0.01) patients had a significantly higher level of CDKN2A protein expression than controls (median = 1.068). The snRNA-seq analysis of two DMD muscles revealed that CDKN2A was mainly expressed in fibro-adipogenic progenitors, satellite cells, and myoblasts.

CONCLUSIONS

We identify CDKN2A expression as a novel biomarker of fibrofatty replacement, which might be a new target for antifibrotic therapy in dystrophinopathies.

Unveiling the Potential of Nelumbo nucifera-Derived Liensinine to Target The Myostatin Protein and to Counteract Muscle Atrophy

Muscle atrophy refers to a decline in muscle mass and function, which has become a global concern due to the aging population. Various clinical trials have investigated the inhibitors of myostatin (MSTN). They have shown promising improvements in muscle function and quality of life. However, there are no drugs specifically targeting MSTN that have been approved for clinical use. In this study, we virtually screened liensinine (LIE), a food (Nelumbo nucifera)-derived compound, with low toxicity, from over 1.1 million compounds. We subsequently identified it as a potential candidate that targets MSTN by a cellular thermal shift assay (CETSA) and drug affinity response target stability (DARTS) assay. Further validation through cellular and in vivo studies demonstrated its promising potential in combating muscle atrophy. The mechanism of action may involve hindering the interaction between MSTN and the activin receptor type IIB (ActRIIB) and downregulating the expression of downstream proteins, including the muscle RING-finger protein-1 (MuRF-1) and muscle atrophy F-box (MAFbx)/Atrogin-1, ultimately promoting muscle regeneration. These results provide a strong foundation for future studies to explore the therapeutic potential of LIE in clinical settings.

Neuromuscular disorders in the omics era

Neuromuscular disorders encompass a spectrum of conditions characterized by primary lesions within the peripheral nervous system, which include the anterior horn cell, peripheral nerve, neuromuscular junction, and muscle. In pediatrics, most of these disorders are linked to genetic causes. Despite the considerable progress, the diagnosis of these disorders remains a challenging due to wide clinical presentation, disease heterogeneity and rarity. It is noteworthy that certain neuromuscular disorders, once deemed untreatable, can now be effectively managed through novel therapies. Biomarkers emerge as indispensable tools, serving as objective measures that not only refine diagnostic accuracy but also provide guidance for therapeutic decision-making and the ongoing monitoring of long-term outcomes. Herein a comprehensive review of biomarkers in neuromuscular disorders is provided. We highlight the role of omics-based technologies that further characterize neuromuscular pathophysiology as well as identify potential therapeutic targets to guide treatment strategies.

Predictors of Loss of Ambulation in Duchenne Muscular Dystrophy: A Systematic Review and Meta-Analysis

Objective

The objective of this study was to describe predictors of loss of ambulation in Duchenne muscular dystrophy (DMD).

Methods

This systematic review and meta-analysis included searches of MEDLINE ALL, Embase, and the Cochrane Database of Systematic Reviews from January 1, 2000, to December 31, 2022, for predictors of loss of ambulation in DMD. Search terms included "Duchenne muscular dystrophy" as a Medical Subject Heading or free text term, in combination with variations of the term "predictor". Risk of bias was assessed using the Newcastle-Ottawa Scale. We performed meta-analysis pooling of hazard ratios of the effects of glucocorticoids (vs. no glucocorticoid therapy) by fitting a common-effect inverse-variance model.

Results

The bibliographic searches resulted in the inclusion of 45 studies of children and adults with DMD from 17 countries across Europe, Asia, and North America. Glucocorticoid therapy was associated with delayed loss of ambulation (overall meta-analysis HR deflazacort/prednisone/prednisolone: 0.44 [95% CI: 0.40-0.48]) (n = 25 studies). Earlier onset of first signs or symptoms, earlier loss of developmental milestones, lower baseline 6MWT (i.e.,<350 vs. ≥350 metres and <330 vs. ≥330 metres), and lower baseline NSAA were associated with earlier loss of ambulation (n = 5 studies). Deletion of exons 3-7, proximal mutations (upstream intron 44), single exon 45 deletions, and mutations amenable of skipping exon 8, exon 44, and exon 53, were associated with prolonged ambulation; distal mutations (intron 44 and downstream), deletion of exons 49-50, and mutations amenable of skipping exon 45, and exon 51 were associated with earlier loss of ambulation (n = 13 studies). Specific single-nucleotide polymorphisms in CD40 gene rs1883832, LTBP4 gene rs10880, SPP1 gene rs2835709 and rs11730582, and TCTEX1D1 gene rs1060575 (n = 7 studies), as well as race/ethnicity and level of family/patient deprivation (n = 3 studies), were associated with loss of ambulation. Treatment with ataluren (n = 2 studies) and eteplirsen (n = 3 studies) were associated with prolonged ambulation. Magnetic resonance biomarkers (MRI and MRS) were identified as significant predictors of loss of ambulation (n = 6 studies). In total, 33% of studies exhibited some risk of bias.

Conclusion

Our synthesis of predictors of loss of ambulation in DMD contributes to the understanding the natural history of disease and informs the design of new trials of novel therapies targeting this heavily burdened patient population.

269th ENMC international workshop: 10 years of clinical trials in Duchenne muscular dystrophy - What have we learned? 9-11 December 2022, Hoofddorp, The Netherlands

There are multiple avenues for therapeutic development in Duchenne muscular dystrophy (DMD), which are highlighted in the first section of this report for the "10 years of Clinical trials in DMD - What have we learned?" workshop. This report then provides an overview of the presentations made at the workshop grouped into the following core themes: trial outcomes, disease heterogeneity, meaningfulness of outcomes and the utility of real-world data in trials. Finally, we present the consensus that was achieved at the workshop on the learning points from 10 years of clinical trials in DMD, and possible action points from these. This includes further work in expanding the scope and range of trial outcomes and assessing the efficacy of new trial structures for DMD. We also highlight several points which should be addressed during future interactions with regulators, such as clinical meaningfulness and the use of real-world data.

Pathogenesis, Intervention, and Current Status of Drug Development for Sarcopenia: A Review

Sarcopenia refers to the loss of muscle strength and mass in older individuals and is a major determinant of fall risk and impaired ability to perform activities of daily living, often leading to disability, loss of independence, and death. Owing to its impact on morbidity, mortality, and healthcare expenditure, sarcopenia in the elderly has become a major focus of research and public policy debates worldwide. Despite its clinical importance, sarcopenia remains under-recognized and poorly managed in routine clinical practice, partly owing to the lack of available diagnostic testing and uniform diagnostic criteria. Since the World Health Organization and the United States assigned a disease code for sarcopenia in 2016, countries worldwide have assigned their own disease codes for sarcopenia. However, there are currently no approved pharmacological agents for the treatment of sarcopenia; therefore, interventions for sarcopenia primarily focus on physical therapy for muscle strengthening and gait training as well as adequate protein intake. In this review, we aimed to examine the latest information on the epidemiology, molecular mechanisms, interventions, and possible treatments with new drugs for sarcopenia.

Dual-energy X-ray absorptiometry measures of lean body mass as a biomarker for progression in boys with Duchenne muscular dystrophy

We evaluated whether whole-body dual-energy X-ray absorptiometry (DXA) measures of lean body mass can be used as biomarkers for disease progression and treatment effects in patients with Duchenne muscular dystrophy. This post hoc analysis utilized data from a randomized, 2-period study of domagrozumab versus placebo in 120 ambulatory boys with DMD. DXA measures of lean body mass were obtained from the whole body (excluding head), arms, legs and appendicular skeleton at baseline and every 16 weeks. Treatment effects on DXA measures for domagrozumab versus placebo were assessed at Week 49. At Week 49, domagrozumab statistically significantly increased lean body mass versus placebo in the appendicular skeleton (p = 0.050) and arms (p < 0.001). The relationship between lean body mass at Week 49 and functional endpoints at Week 97 was evaluated. Changes in lean body mass at Week 49 in all regions except arms were significantly correlated with percent change from baseline in 4-stair climb (4SC) at Week 97. DXA-derived percent lean mass at Week 49 also correlated with 4SC and North Star Ambulatory Assessment at Week 97. These data indicate that whole-body DXA measures can be used as biomarkers for treatment effects and disease progression in patients with DMD, and warrant further investigation.Trial registration: ClinicalTrials.gov, NCT02310763; registered 8 December 2014.