Timed Rise from Floor as a Predictor of Disease Progression in Duchenne Muscular Dystrophy: An Observational Study

Natural history of skeletal muscle laminopathies: a 2-year prospective study

Skeletal muscle laminopathies (SMLs) are rare disorders characterized by skeletal muscle involvement caused by mutations in LMNA gene. To date, the natural history of SMLs has not been clearly elucidated. Through a 2-year prospective study, we aimed to describe the natural history of SMLs. We enrolled 26 SMLs patients, assessed with: North Star Ambulatory Assessment scale (NSAA), timed tests, manual muscle testing, joint range of motion, six-minutes walking test (6MWT); respiratory evaluation including forced vital capacity (FVC) and forced expiratory volume at 1 second (FEV1); individualized neuromuscular quality of life (INQoL). Muscular performance with the aforementioned tools significantly correlated with phenotypes at the baseline, showing the worse outcome in those with autosomal dominant Emery-Dreifuss muscular dystrophy as compared to limb girdle phenotype. NSAA score significantly (p = 0.0005) worsened during the 2-year follow-up. Moreover, the respiratory function through FVC and FEV1 significantly (p = 0.0086 and p = 0.0290, respectively) deteriorated over the follow-up period. 6MWT, INQoL and timed tests did not significantly change, as well as ankle, knee, and elbow contractures. This study showed a slow progression of motor and respiratory function in SMLs patients over a period of 2 years.

A 5-year natural history study in LAMA2-related muscular dystrophy and SELENON-related myopathy: the Extended LAST STRONG study

BACKGROUND

SELENON-related myopathy (SELENON-RM) is a rare congenital myopathy characterized by slowly progressive axial muscle weakness, rigidity of the spine, scoliosis, and respiratory insufficiency. Laminin-a2-related muscular dystrophy (LAMA2-MD) has a similar clinical phenotype, which ranges from severe, early-onset congenital muscular dystrophy type 1A (MDC1A) to milder forms presenting as childhood- or adult-onset limb-girdle type muscular dystrophy. The first 1.5-year natural history follow-up showed that 90% of the patients had low bone quality, respiratory impairments were found in all SELENON-RM and most of the LAMA2-MD patients, and many had cardiac risk factors. However, further extensive knowledge on long-term natural history data, and clinical and functional outcome measures is needed to reach trial readiness. Therefore, we extended the natural history study with 3- and 5-year follow-up visits (Extended LAST STRONG).

METHODS

The Extended LAST STRONG is a long-term natural history study in Dutch-speaking patients of all ages diagnosed with genetically confirmed SELENON-RM or LAMA2-MD, starting in September 2023. Patients visit our hospital twice over a period of 2 years to complete a 5-year follow up from the initial LAST-STRONG study. At both visits, they undergo standardized neurological examination, hand-held dynamometry (age ≥ 5 years), functional measurements, muscle ultrasound, respiratory assessments (spirometry, maximal inspiratory and expiratory pressure, sniff nasal inspiratory pressure; age ≥ 5 years), Dual-energy X-ray absorptiometry (DEXA-)scan (age ≥ 2 years), X-ray of the left hand (age ≤ 17 years), lower extremity MRI (age ≥ 10 years), accelerometry for 8 days (age ≥ 2 years), and questionnaires (patient report and/or parent proxy; age ≥ 2 years). All examinations are adapted to the patient's age and functional abilities. Disease progression between all subsequent visits and relationships between outcome measures will be assessed.

DISCUSSION

This study will provide valuable insights into the 5-year natural history of patients with SELENON-RM and LAMA2-MD and contribute to further selecting relevant and sensitive to change clinical and functional outcome measures. Furthermore, this data will help optimize natural history data collection in clinical care and help develop clinical care guidelines.

TRIAL REGISTRATION

This study protocol including the patient information and consent forms has been approved by medical ethical reviewing committee ('METC Oost-Nederland'; https://www.ccmo.nl/metcs/erkende-metcs/metc-oost-nederland , file number: 2023-16401). It is registered at ClinicalTrials.gov (NCT06132750; study registration date: 2023-10-05; study first passed date: 2023-11-15).

Timed rolling and rising tests in Duchenne muscular dystrophy ambulant boys: a feasibility study

BACKGROUND

Functional activities are extensively used in motor assessments of patients with Duchenne muscular dystrophy. The role of timed items has been reported as an early prognostic factor for disease progression. However, there are two functional activities that are not widely assessed in clinical practice among Duchenne muscular dystrophy patients: rolling and bed rising. This study aimed to investigate whether the 360-degree roll (roll) and supine to sit-to-edge (bed rise) measurements are feasible tools reflecting the functional status of ambulatory DMD children by establishing possible correlations between validated measures: the Vignos Scale (VS), timed rise from floor and the 6-Minute Walk Test (6MWT).

METHODS

A total of 32 ambulant boys with DMD were assessed using timed items, the 6MWT and VS.

RESULTS

The roll and bed rise are correlated with each other. The 6MWT, the floor rise and VS are correlated with the roll and with the bed rise.

CONCLUSIONS

Findings offer preliminary empirical evidence addressing feasibility and safety of roll and bed rise measurements. There is a potential clinical utility of these tests in assessing functional status of DMD ambulant patients.

LAMA2-Related Muscular Dystrophy Across the Life Span: A Cross-sectional Study

Background and Objectives

LAMA2-related muscular dystrophy (LAMA2-MD) is a rare neuromuscular disease characterized by proximal and axial muscle weakness, rigidity of the spine, scoliosis, and respiratory impairment. No curative treatment options exist, yet promising preclinical studies are ongoing. Currently, there is a paucity on natural history data, and appropriate clinical and functional outcome measures are needed. We aim for deep clinical phenotyping, establishment of a well-characterized baseline cohort for prospective follow-up and recruitment for future clinical trials, improvement of clinical care, and selection of outcome measures for reaching trial readiness.

Methods

We performed a cross-sectional, single-center, observational study. This study included neurologic examination and functional measurements among others the Motor Function Measure 20/32 (MFM-20/32) as primary outcome measure, accelerometry, questionnaires, muscle ultrasound, respiratory function tests, electrocardiography and echocardiography, and dual-energy X-ray absorptiometry.

Results

Twenty-seven patients with genetically confirmed LAMA2-MD were included (21 ± 13 years; M = 9; ambulant = 7). Axial and proximal muscle weakness was most pronounced. The mean MFM-20/32 score was 42.0% ± 29.4%, with domain 1 (standing and transfers) being severely affected and domain 3 (distal muscle function) relatively spared. Physical activity as measured through accelerometry showed very strong correlations to MFM-20/32 (Pearson correlation, -0.928, p < 0.01). Muscle ultrasound showed symmetrically increased echogenicity, with the sternocleidomastoid muscle most affected. Respiratory function was impaired in 85% of patients without prominent diaphragm dysfunction and was independent of age. Ten patients (37%) needed (non)invasive ventilatory support. Cardiac assessment revealed QRS fragmentation in 62%, abnormal left ventricular global longitudinal strain in 25%, and decreased left ventricular ejection fraction in 14% of patients. Decreased bone quality leading to fragility fractures was seen in most of the patients.

Discussion

LAMA2-MD has a widely variable phenotype. Based on the results of this cross-sectional study and current standards of care for congenital muscular dystrophies, we advise routine cardiorespiratory follow-up and optimization of bone quality. We propose MFM-20/32, accelerometry, and muscle ultrasound for assessing disease severity and progression. For definitive clinical recommendations and outcome measures, natural history data are needed.

Clinical Trials Registration

This study was registered at clinicaltrials.gov (NCT04478981, 21 July 2020). The first patient was enrolled in September 2020.

Is it time for genetic modifiers to predict prognosis in Duchenne muscular dystrophy?

Patients with Duchenne muscular dystrophy (DMD) show clinically relevant phenotypic variability, despite sharing the same primary biochemical defect (dystrophin deficiency). Factors contributing to this clinical variability include allelic heterogeneity (specific DMD mutations), genetic modifiers (trans-acting genetic polymorphisms) and variations in clinical care. Recently, a series of genetic modifiers have been identified, mostly involving genes and/or proteins that regulate inflammation and fibrosis - processes increasingly recognized as being causally linked with physical disability. This article reviews genetic modifier studies in DMD to date and discusses the effect of genetic modifiers on predicting disease trajectories (prognosis), clinical trial design and interpretation (inclusion of genotype-stratified subgroup analyses) and therapeutic approaches. The genetic modifiers identified to date underscore the importance of progressive fibrosis, downstream of dystrophin deficiency, in driving the disease process. As such, genetic modifiers have shown the importance of therapies aimed at slowing this fibrotic process and might point to key drug targets.

SELENON-Related Myopathy Across the Life Span, a Cross-Sectional Study for Preparing Trial Readiness

BACKGROUND

SELENON(SEPN1)-related myopathy (SELENON-RM) is a rare congenital neuromuscular disease characterized by proximal and axial muscle weakness, spinal rigidity, scoliosis and respiratory impairment. No curative treatment options exist, but promising preclinical studies are ongoing. Currently, natural history data are lacking, while selection of appropriate clinical and functional outcome measures is needed to reach trial readiness.

OBJECTIVE

We aim to identify all Dutch and Dutch-speaking Belgian SELENON-RM patients, deep clinical phenotyping, trial readiness and optimization of clinical care.

METHODS

This cross-sectional, single-center, observational study comprised neurological examination, functional measurements including Motor Function Measurement 20/32 (MFM-20/32) and accelerometry, questionnaires, muscle ultrasound, respiratory function tests, electro- and echocardiography, and dual-energy X-ray absorptiometry.

RESULTS

Eleven patients with genetically confirmed SELENON-RM were included (20±13 (3-42) years, 73% male). Axial and proximal muscle weakness were most pronounced. The mean MFM-20/32 score was 71.2±15.1%, with domain 1 (standing and transfers) being most severely affected. Accelerometry showed a strong correlation with MFM-20/32. Questionnaires revealed impaired quality of life, pain and problematic fatigue. Muscle ultrasound showed symmetrically increased echogenicity in all muscles. Respiratory function, and particularly diaphragm function, was impaired in all patients, irrespective of the age. Cardiac assessment showed normal left ventricular systolic function in all patients but abnormal left ventricular global longitudinal strain in 43% of patients and QRS fragmentation in 80%. Further, 80% of patients showed decreased bone mineral density on dual-energy X-ray absorptiometry scan and 55% of patients retrospectively experienced fragility long bone fractures.

CONCLUSIONS

We recommend cardiorespiratory follow-up as a part of routine clinical care in all patients. Furthermore, we advise vitamin D supplementation and optimization of calcium intake to improve bone quality. We recommend management interventions to reduce pain and fatigue. For future clinical trials, we propose MFM-20/32, accelerometry and muscle ultrasound to capture disease severity and possibly disease progression.

Peak functional ability and age at loss of ambulation in Duchenne muscular dystrophy

AIM

To correlate the North Star Ambulatory Assessment (NSAA) and timed rise from floor (TRF) recorded at age of expected peak with age at loss of ambulation (LOA) in Duchenne muscular dystrophy (DMD).

METHOD

Male children with DMD enrolled in the UK North Start Network database were included according to the following criteria: follow-up longer than 3 years, one NSAA record between 6 years and 7 years 6 months (baseline), at least one visit when older than 8 years. Data about corticosteroid treatment, LOA, genotype, NSAA, and TRF were analysed. Age at LOA among the different groups based on NSAA and TRF was determined by log-rank tests. Cox proportional hazard models were used for multivariable analysis.

RESULTS

A total of 293 patients from 13 different centres were included. Mean (SD) age at first and last visit was 5 years 6 months (1 year 2 months) and 12 years 8 months (2 years 11 months) (median follow-up 7 years 4 months). Higher NSAA and lower TRF at baseline were associated with older age at LOA (p<0.001). Patients scoring NSAA 32 to 34 had a probability of 0.61 of being ambulant when older than 13 years compared with 0.34 for those scoring 26 to 31. In multivariable analysis, NSAA, TRF, and corticosteroid daily regimen (vs intermittent) were all independently associated with outcome (p=0.01).

INTERPRETATION

Higher functional abilities at peak are associated with older age at LOA in DMD. This information is important for counselling families. These baseline measures should also be considered when designing clinical trials.

Longitudinal Motor Functional Outcomes and Magnetic Resonance Imaging Patterns of Muscle Involvement in Upper Limbs in Duchenne Muscular Dystrophy

Background and Objectives: The aim of this study was to evaluate longitudinal changes using both upper limb muscle Magnetic Resonance Imaging (MRI) at shoulder, arm and forearm levels and Performance of upper limb (PUL) in ambulant and non-ambulant Duchenne Muscular Dystrophy (DMD) patients. We also wished to define whether baseline muscle MRI could help to predict functional changes after one year. Materials and Methods: Twenty-seven patients had both baseline and 12month muscle MRI and PUL assessments one year later. Results: Ten were ambulant (age range 5–16 years), and 17 non ambulant (age range 10–30 years). Increased abnormalities equal or more than 1.5 point on muscle MRI at follow up were found on all domains: at shoulder level 12/27 patients (44%), at arm level 4/27 (15%) and at forearm level 6/27 (22%). Lower follow up PUL score were found in 8/27 patients (30%) at shoulder level, in 9/27 patients (33%) at mid-level whereas no functional changes were found at distal level. There was no constant association between baseline MRI scores and follow up PUL scores at arm and forearm levels but at shoulder level patients with moderate impairment on the baseline MRI scores between 16 and 34 had the highest risk of decreased function on PUL over a year. Conclusions: Our results confirmed that the integrated use of functional scales and imaging can help to monitor functional and MRI changes over time.

Lessons Learned from Discontinued Clinical Developments in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked condition caused by a deficiency of functional dystrophin protein. Patients experience progressive muscle weakness, cardiomyopathy and have a decreased life expectancy. Standards of care, including treatment with steroids, and multidisciplinary approaches have extended the life expectancy and improved the quality of life of patients. In the last 30 years, several compounds have been assessed in preclinical and clinical studies for their ability to restore functional dystrophin levels or to modify pathways involved in DMD pathophysiology. However, there is still an unmet need with regards to a disease-modifying treatment for DMD and the attrition rate between early-phase and late-phase clinical development remains high. Currently, there are 40 compounds in clinical development for DMD, including gene therapy and antisense oligonucleotides for exon skipping. Only five of them have received conditional approval in one jurisdiction subject to further proof of efficacy. In this review, we present data of another 16 compounds that failed to complete clinical development, despite positive results in early phases of development in some cases. We examine the reasons for the high attrition rate and we suggest solutions to avoid similar mistakes in the future.

Fondazione Telethon and Unione Italiana Lotta alla Distrofia Muscolare, a successful partnership for neuromuscular healthcare research of value for patients

In 2001, Fondazione Telethon and the Italian muscular dystrophy patient organisation Unione Italiana Lotta alla Distrofia Muscolare joined their efforts to design and launch a call for grant applications specifically dedicated to clinical projects in the field of neuromuscular disorders. This strategic initiative, run regularly over the years and still ongoing, aims at supporting research with impact on the daily life of people with a neuromuscular condition and is centred on macro-priorities identified by the patient organisation. It is investigator-driven, and all proposals are peer-reviewed for quality and feasibility. Over the years, this funding program contributed to strengthening the activities of the Italian neuromuscular clinical network, reaching many achievements in healthcare research. Moreover, it has been an enabling factor for innovative therapy experimentation at international level and prepared the clinical ground to make therapies available to Italian patients. The ultimate scope of healthcare research is to ameliorate the delivery of care. In this paper, the achievements of the funded studies are analysed also from this viewpoint, to ascertain to which extent they have fulfilled the original goals established by the patient organisation. The evidence presented indicates that this has been a highly fruitful program. Factors that contributed to its success, lessons learned, challenges, and issues that remain to be addressed are discussed to provide practical examples of an experience that could inspire also other organizations active in the field of rare disease research.

Dexamethasone-induced sarcopenia and physical frailty in children with acute lymphoblastic leukemia: Protocol for a prospective cohort study (Preprint)

Background

During treatment for pediatric acute lymphoblastic leukemia (ALL), children receive high doses of dexamethasone for its apoptotic effect on leukemia cells; however, muscle atrophy is a well-known serious side effect. Muscle atrophy (loss of muscle mass) accompanied by a decreased muscle strength may lead to a generalized impaired skeletal muscle state called sarcopenia. Loss of muscle mass is also an indicator of physical frailty, which is defined as a state of increased vulnerability that is characterized by co-occurrence of low muscle mass, muscle weakness, fatigue, slow walking speed, and low physical activity. Both sarcopenia and physical frailty are related to an increased risk of infections, hospitalizations, and decreased survival in children with chronic diseases.

Objective

This study aims to (1) estimate the occurrence of sarcopenia and physical frailty in children during ALL maintenance therapy, (2) evaluate the effect of administering dexamethasone, and (3) explore determinants associated with these outcomes.

Methods

This prospective study is being pursued within the framework of the DexaDays-2 study: a randomized controlled trial on neurobehavioral side effects in pediatric patients with ALL. A total of 105 children (3-18 years) undergoing ALL maintenance treatment at the Princess Máxima Center for Pediatric Oncology are included in this study. Sarcopenia/frailty assessments are performed before and just after a 5-day dexamethasone course. A subset of 50 children participating in the DexaDays-2 trial because of severe dexamethasone-induced neurobehavioral problems were assessed at 3 additional timepoints. The sarcopenia/frailty assessment consists of bioimpedance analysis (skeletal muscle mass [SMM]), handheld dynamometry (handgrip strength), Pediatric Quality of Life Inventory Multidimensional Fatigue Scale (fatigue), Timed Up and Go Test (TUG; walking speed), and physical activity questionnaires. To evaluate potential change in sarcopenia/frailty components after a 5-day dexamethasone administration, a paired Student t test or Mann-Whitney U test will be used. Because of the presence of repeated measurements, generalized linear mixed models will be used to estimate the effect of dexamethasone on sarcopenia and frailty outcomes. Multivariable regression models will be estimated to investigate associations between the assessment scores and patient and treatment-related factors.

Results

Patient accrual started in 2018 and was finalized in spring 2021. From autumn 2021 onward final data analyses will be performed.

Conclusions

This first study combining parameters of sarcopenia and physical frailty is of importance because these conditions can seriously complicate continuation of ALL therapy, independence in physical functioning, reaching motor milestones, and participating in daily life activities. The results will provide knowledge about these complications, the association between dexamethasone treatment and muscle loss and other components of frailty, and therefore insights into the severity of this side effect. By exploring potential determinants that may be associated with sarcopenia and physical frailty, we may be able to identify children at risk at an earlier stage and provide timely interventions.

International Registered Report Identifier (IRRID)

DERR1-10.2196/33517

North Star Ambulatory Assessment changes in ambulant Duchenne boys amenable to skip exons 44, 45, 51, and 53: A 3 year follow up

Introduction

The aim of this study was to report 36-month longitudinal changes using the North Star Ambulatory Assessment (NSAA) in ambulant patients affected by Duchenne muscular dystrophy amenable to skip exons 44, 45, 51 or 53.

Materials and methods

We included 101 patients, 34 had deletions amenable to skip exon 44, 25 exon 45, 19 exon 51, and 28 exon 53, not recruited in any ongoing clinical trials. Five patients were counted to skip exon 51 and 53 since they had a single deletion of exon 52.

Results

The difference between subgroups (skip 44, 45, 51 and 53) was significant at 12 (p = 0.043), 24 (p = 0.005) and 36 months (p≤0.001).

Discussion

Mutations amenable to skip exons 53 and 51 had lower baseline values and more negative changes than the other subgroups while those amenable to skip exon 44 had higher scores both at baseline and at follow up.

Conclusion

Our results confirm different progression of disease in subgroups of patients with deletions amenable to skip different exons. This information is relevant as current long term clinical trials are using the NSAA in these subgroups of mutations.

Effect of a multicomponent nutritional supplement on functional outcomes for Duchenne muscular dystrophy: A randomized controlled trial

BACKGROUND & AIMS

Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular condition causing progressive muscle weakness and premature death. Whilst effective treatments such as gene therapy are developed, families often seek complementary therapies such as nutrition supplements to help their son maintain function; however, there is limited evidence supporting the use of nutritional supplements in DMD. This study aimed to compare the effect of a Standard nutritional supplement with an Enhanced nutritional supplement combining three nutriceuticals on functional outcomes in ambulatory boys with Duchenne muscular dystrophy (DMD).

DESIGN

A 50-week double blinded, randomized, controlled crossover trial was conducted in four Australian neuromuscular centres. Primary outcome measures were 6-min walk distance (6MWD) and community ambulation (StepWatch™ Activity Monitoring). Secondary outcome measures included body composition and quality of life. Serum 25-hydroxyvitamin D was measured.

RESULTS

Twenty-seven boys completed the intervention. Traditional crossover analysis demonstrated the Enhanced supplement compared to the Standard supplement was associated with a difference of +12 (95% CI: -16, 40) metres in 6MWD, +0.5 (95% CI: -53, 54) inactive minutes per day and -95 (95% CI: -887, 696) steps per day. A mixed effect model indicated a potentially clinically important effect of the Enhanced supplement on the 6MWD of +31 (95% CI: -19, 81) metres. Mean serum 25 hydroxyvitamin D levels at week 50 was 94 (95% CI: 84, 104) nmol/L. There was no observable effect of either supplement regime on body composition or quality of life.

CONCLUSIONS

Whilst a positive effect of the Enhanced supplement on functional outcomes was observed, this finding was inconclusive due to the small sample size. The results do not support the use of combined nutritional supplements to improve body composition or quality of life in DMD. A dose of 2000 IU vitamin D was an adequate dose to raise serum 25-hydroxyvitamin D over 50 weeks.

CLINICAL TRIAL REGISTRY

Registry #: ACTRN12610000462088, http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12610000462088.

Effects of lumbar lordosis increment on gait deteriorations in ambulant boys with Duchenne Muscular Dystrophy: A cross-sectional study

BACKGROUND

Increment of lumbar lordosis, a frequent spinal finding in Duchenne Muscular Dystrophy (DMD), is a compensatory mechanism secondary to muscle weakness. However, excessive lumbar lordosis may change the position of the center of mass, and lead to balance and walking difficulties.

OBJECTIVE

To study the relationship between factors that may influence ambulatory function in boys with DMD and to investigate the effects of lumbar lordosis increment on gait and balance perturbations.

METHODS

Twenty-one ambulant patients with DMD and 10 healthy boys were included. Lumbar lordosis and thoracic kyphosis angles, dynamic and static balance tests, ambulatory function, muscle strength, and disease severity were assessed. Usage of steroids and orthotic devices were recorded. Scoliosis was assessed on radiographs. Receiver operator characteristic curves were formed and area under curve (AUC) measurements were performed to assess the ability of the tests to discriminate ambulatory status and optimal cut-off values were established according to the Youden index.

RESULTS

The amount of lumbar lordosis correlated strongly and negatively with quality of ambulation (r = -0.710) and moderately with performance on balance tests. The strength of both upper limbs and lower limbs muscles were not associated with any of the variables. According to the AUC analysis, patients with a lumbar lordosis higher than 36° had worse scores on gait and dynamic balance tests.

CONCLUSION

Ambulation and dynamic balance are negatively affected by the increment of lumbar lordosis with a cut-off point of 36°in boys with DMD.

Can simple and low-cost motor function assessments help in the diagnostic suspicion of Duchenne muscular dystrophy?

OBJECTIVE

Duchenne muscular dystrophy, an X-linked genetic disease, leads to progressive muscle weakness mainly in the lower limbs. Motor function tests help to monitor disease progression. Can low-cost, simple assessments help in the diagnostic suspicion of Duchenne muscular dystrophy? The authors aim to define the sensitivity of time to rise from the floor, time to walk 10meters, and time to run 10meters, evaluating them as eventual diagnostic screening tools.

METHODS

This is an analytical, observational, retrospective (1998-2015), and prospective study (2015-2018). Cases were recruited from the database of the pediatric neurology department and the healthy, from child care consultations, with normal gait development (up to 15 months) and without other comorbidities (neuromuscular, pulmonary, heart diseases) from the same university hospital.

RESULTS

128 Duchenne muscular dystrophy patients and 344 healthy children were analyzed, equally distributed in age groups. In Duchenne muscular dystrophy, there is a progressive increase in the means of the times to perform the motor tests according to the age group, which accelerates very abruptly after 7 years of age. Healthy children acquire maximum motor capacity at 6 years and stabilize their times. The time to rise showed a p-value <0.05 and a strong association (effect size [ES] >0.8) in all age groups (except at 12 years), with time to walk 10 meters from 9 years, and with time to run 10 meters , from 5 years. The 100% sensitivity points were defined as follows: time to rise, at 2s; time to walk 10 meters, 5s; time to run 10 meters, 4s.

CONCLUSIONS

Time to rise is a useful and simple tool in the screening of neuromuscular disorders such as Duchenne muscular dystrophy, a previously incurable disease with new perspectives for treatment.

Prognostic factors for changes in the timed 4-stair climb in patients with Duchenne muscular dystrophy, and implications for measuring drug efficacy: A multi-institutional collaboration

The timed 4-stair climb (4SC) assessment has been used to measure function in Duchenne muscular dystrophy (DMD) practice and research. We sought to identify prognostic factors for changes in 4SC, assess their consistency across data sources, and the extent to which prognostic scores could be useful in DMD clinical trial design and analysis. Data from patients with DMD in the placebo arm of a phase 3 trial (Tadalafil DMD trial) and two real-world sources (Universitaire Ziekenhuizen, Leuven, Belgium [Leuven] and Cincinnati Children's Hospital Medical Center [CCHMC]) were analyzed. One-year changes in 4SC completion time and velocity (stairs/second) were analyzed. Prognostic models included age, height, weight, steroid use, and multiple timed function tests and were developed using multivariable regression, separately in each data source. Simulations were used to quantify impacts on trial sample size requirements. Data on 1-year changes in 4SC were available from the Tadalafil DMD trial (n = 92) Leuven (n = 67), and CCHMC (n = 212). Models incorporating multiple timed function tests, height, and weight significantly improved prognostic accuracy for 1-year change in 4SC (R²: 29%-36% for 4SC velocity, and 29%-34% for 4SC time) compared to models including only age, baseline 4SC and steroid duration (R²:8%-17% for 4SC velocity and 2%-13% for 4SC time). Measures of walking and rising ability contributed important prognostic information for changes in 4SC. In a randomized trial with equal allocation to treatment and placebo, adjustment for such a prognostic score would enable detection (at 80% power) of a treatment effect of 0.25 stairs/second with 100–120 patients, compared to 170–190 patients without prognostic score adjustment. Combining measures of ambulatory function doubled prognostic accuracy for 1-year changes in 4SC completion time and velocity. Randomized clinical trials incorporating a validated prognostic score could reduce sample size requirements by approximately 40%. Knowledge of important prognostic factors can also inform adjusted comparisons to external controls.

Effect of Combination l-Citrulline and Metformin Treatment on Motor Function in Patients With Duchenne Muscular Dystrophy: A Randomized Clinical Trial

IMPORTANCE

Nitric oxide precursors, such as the amino acid l-arginine and the biguanide antidiabetic drug metformin, have been associated with metabolism and muscle function in patients with Duchenne muscular dystrophy (DMD). The treatment of DMD remains an unmet medical need.

OBJECTIVE

To evaluate the benefits and harms of a combination of l-citrulline and metformin treatment among patients with DMD.

DESIGN, SETTING, AND PARTICIPANTS

A single-center randomized double-blind placebo-controlled parallel-group clinical trial was conducted between December 12, 2013, and March 30, 2016, at the University Children's Hospital Basel in Switzerland. A total of 47 ambulant male patients aged 6.5 to 10 years with genetically confirmed DMD were recruited locally and from the patient registries of Switzerland, Germany, Austria, and France. Data were analyzed from April 6, 2016, to September 5, 2019.

INTERVENTIONS

Patients in the treatment group received 2500 mg of l-citrulline and 250 mg of metformin (combination therapy) 3 times a day for 26 weeks compared with patients in the control group, who received placebo.

MAIN OUTCOMES AND MEASURES

The primary end point was the change in transfer and standing posture, as assessed by the first dimension of the Motor Function Measure, version 32, from baseline to week 26. Secondary end points included assessments of timed function, quantitative muscle force, biomarkers for muscle necrosis, and adverse events. The 2 prespecified subgroups comprised patients who were able to walk 350 m or more in 6 minutes (stable subgroup) and patients who were not able to walk 350 m in 6 minutes (unstable subgroup) at baseline.

RESULTS

Among 49 ambulant male children with DMD who were screened for eligibility, 47 patients with a mean (SD) age of 8.2 (1.1) years were randomized to a treatment group receiving combination therapy (n = 23) or a control group receiving placebo (n = 24), and 45 patients completed the study. No significant differences between groups were found in the results of timed function and muscle force tests for overall, proximal and axial, and distal motor function. Among patients receiving combination therapy, the Motor Function Measure first dimension subscore decrease was 5.5% greater than that of patients receiving placebo (95% CI, -1.0% to 12.1%; P = .09). The administration of combination therapy had significantly favorable effects on the first dimension subscore decrease among the 29 patients in the stable subgroup (6.7%; 95% CI, 0.9%-12.6%; P = .03) but not among the 15 patients in the unstable subgroup (3.9%; 95% CI, -13.2% to 20.9%; P = .63). Overall, the treatment was well tolerated with only mild adverse effects.

CONCLUSIONS AND RELEVANCE

Treatment with combination therapy was not associated with an overall reduction in motor function decline among ambulant patients with DMD; however, a reduction in motor function decline was observed among the stable subgroup of patients treated with combination therapy. The statistically nonsignificant difference of distal motor function in favor of combination therapy and the reduced degeneration of muscle tissue appear to support the treatment concept, but the study may have lacked sufficient statistical power. Further research exploring this treatment option with a greater number of patients is warranted.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01995032.

Validation of an ambient measurement system (AMS) for physical activities in a paediatric population

Ambient measurement systems (AMSs) can enable continuous assessment of functional performance at home, increasing the availability of data for monitoring of neuromuscular disease. An AMS passively measures movement whenever someone is in range of the sensor, without the need for any wearable sensors. The current study evaluates the performance of an AMS for three metrics associated with functional assessments in Duchenne muscular dystrophy (DMD): ambulation speed, rise-to-stand speed and arm-raise speed. Healthy paediatric subjects performed a series of functional tasks and were graded by both a human rater and an AMS. Linear mixed-effect models were fit to calculate agreement between the two measurement methods. For all activities, the AMS and human rater supplied similar measurements of average speed, with correlation coefficients of 0.76-0.92 and systematic differences ranging in magnitude from 0 to 0.48 m per second. The largest systematic difference was for the 10-m run, which was likely due to human rater reaction time. Systematic differences in arm-raise measurements were due to incomplete execution of movements by test participants. These results are consistent with previous studies comparing automated and manual measurements of movement. This study demonstrates that an AMS device is able to measure ambulation speed, rise-to-stand speed and arm-raise speed in a paediatric population in a controlled setting without the need for complicated installation, calibration or worn sensors.

Long-term natural history data in Duchenne muscular dystrophy ambulant patients with mutations amenable to skip exons 44, 45, 51 and 53

INTRODUCTION

The aim of this international collaborative effort was to report 36-month longitudinal changes using the 6MWT in ambulant patients affected by Duchenne muscular dystrophy amenable to skip exons 44, 45, 51 or 53.

MATERIALS AND METHODS

Of the 92 patients included in the study, 24 had deletions amenable to skip exon 44, 27 exon 45, 18 exon 51, and 28 exon 53. Five patients with a single deletion of exon 52 were counted in both subgroups skipping exon 51 and 53.

RESULTS

The difference between subgroups amenable to skip different exons was not significant at 12 months but became significant at both 24 (p≤0.05) and 36 months (p≤0.01).

DISCUSSION

Mutations amenable to skip exon 53 had lower baseline values and more negative changes than the other subgroups while those amenable to skip exon 44 had better results both at baseline and at follow up. Deletions amenable to skip exon 45 were associated with a more variable pattern of progression. Single exon deletions were more often associated with less drastic changes but this was not always true in individual cases.

CONCLUSION

Our results confirm that the progression of disease can differ between patients with different deletions, although the changes only become significant from 24 months onwards. This information is relevant because there are current clinical trials specifically targeting patients with these subgroups of mutations.

A mini-review and implementation model for using ataluren to treat nonsense mutation Duchenne muscular dystrophy

AIM

Ataluren has been approved for treating nonsense mutation Duchenne muscular dystrophy (nmDMD), and there are currently discussions concerning drug access and applications beyond the development programme. This study provides an overview of nmDMD and ataluren, stipulates clinical rules for treatment initiation and discontinuation and proposes a model for the implementation of orphan drugs in clinical practice in Sweden.

METHODS

This was a targeted mini-review of the literature from 1995 to 2018, which included cohort studies, guidelines, randomised clinical trials, clinical commentaries and reviews. The review covered the pathophysiology, epidemiology and burden of nmDMD and the clinical programme for ataluren.

RESULTS

Based on the current evidence, and our experiences, we recommend that patients with nmDMD should be given ataluren as soon as possible after diagnosis and this treatment should continue until they reach a forced vital capacity of <30%, and, or, a score of at least six on the Brooke upper extremity scale. We propose an implementation model that comprises a coordinating specialist physician and a national expert committee responsible for providing clinical intelligence to ensure appropriate use.

CONCLUSION

Our clinical recommendations and proposed implementation model will inform the optimum medical management of nmDMD in Sweden and help ensure timely, equal access to ataluren and similar orphan drugs.

Anti-HMGCR myopathy may resemble limb-girdle muscular dystrophy

Objective

To determine the prevalence and clinical features of anti-HMGCR myopathy among patients with presumed limb-girdle muscular dystrophy (LGMD) in whom genetic testing has failed to elucidate causative mutations.

Methods

Patients with presumed LGMD and unrevealing genetic testing were selected based on a few clinico-pathologic features and tested for anti-HMGCR autoantibodies (n = 11). These clinico-pathologic features are peak creatine kinase (CK) greater than 1,000 IU/L and at least 3 of the following features: (1) limb-girdle pattern of weakness, (2) selective involvement of posterior thigh on clinical examination or muscle imaging, (3) dystrophic changes on muscle biopsy, and (4) no family history of muscular dystrophy.

Results

Six patients tested positive for anti-HMGCR autoantibodies. In 4, there was a presymptomatic phase, lasting as long as 10 years, characterized by elevated CK levels without weakness. Muscle biopsies revealed variable degrees of a dystrophic pathology without prominent inflammation. In an independent cohort of patients with anti-HMGCR myopathy, 17 of 51 (∼33%) patients were initially presumed to have a form of LGMD based on clinico-pathologic features but were ultimately found to have anti-HMGCR myopathy. Most of these patients responded favorably to immunomodulatory therapies, evidenced by reduction of CK levels and improved strength.

Conclusions

Anti-HMGCR myopathy can resemble LGMD. Diagnosis of patients with a LGMD-like presentation of anti-HMGCR myopathy is critical because these patients may respond favorably to immunotherapy, especially those with shorter disease duration.

The Italian neuromuscular registry: a coordinated platform where patient organizations and clinicians collaborate for data collection and multiple usage

BACKGROUND

The worldwide landscape of patient registries in the neuromuscular disease (NMD) field has significantly changed in the last 10 years, with the international TREAT-NMD network acting as strong driver. At the same time, the European Medicines Agency and the large federations of rare disease patient organizations (POs), such as EURORDIS, contributed to a great cultural change, by promoting a paradigm shift from product-registries to patient-centred registries. In Italy, several NMD POs and Fondazione Telethon undertook the development of a TREAT-NMD linked patient registry in 2009, with the referring clinical network providing input and support to this initiative through the years. This article describes the outcome of this joint effort and shares the experience gained.

METHODS

The Italian NMD registry is based on an informatics technology platform, structured according to the most rigorous legal national and European requirements for management of patient sensitive data. A user-friendly web interface allows both direct patients and clinicians' participation. The platform's design permits expansion to incorporate new modules and new registries, and is suitable of interoperability with other international efforts.

RESULTS

When the Italian NMD Registry was initiated, an ad hoc legal entity (NMD Registry Association) was devised to manage registries' data. Currently, several disease-specific databases are hosted on the platform. They collect molecular and clinical details of individuals affected by Duchenne or Becker muscular dystrophy, Charcot-Marie-Tooth disease, transthyretin type-familial amyloidotic polyneuropathy, muscle glycogen storage disorders, spinal and bulbar muscular atrophy, and spinal muscular atrophy. These disease-specific registries are at different stage of development, and the NMD Registry itself has gone through several implementation steps to fulfil different technical and governance needs. The new governance model is based on the agreement between the NMD Registry Association and the professional societies representing the Italian NMD clinical network. Overall, up to now the NMD registry has collected data on more than 2000 individuals living with a NMD condition.

CONCLUSIONS

The Italian NMD Registry is a flexible platform that manages several condition-specific databases and is suitable to upgrade. All stakeholders participate in its management, with clear roles and responsibilities. This governance model has been key to its success. In fact, it favored patient empowerment and their direct participation in research, while also engaging the expert clinicians of the Italian network in the collection of accurate clinical data according to the best clinical practices.

Brazilian consensus on Duchenne muscular dystrophy. Part 2: rehabilitation and systemic care

ABSTRACT Significant advances in the understanding and management of Duchenne muscular dystrophy (DMD) have occurred since the publication of international guidelines for DMD care in 2010. Our objective was to provide an evidence-based national consensus statement for multidisciplinary care of DMD in Brazil. A combination of the Delphi technique with a systematic review of studies from 2010 to 2016 was employed to classify evidence levels and grade of recommendations for the guideline. Our recommendations were divided in two parts. Guideline methodology and overall disease concept descriptions are found in Part 1. Here we present Part 2, where we provide the results and recommendations on rehabilitation and systemic care for DMD.

Long-term effects of glucocorticoids on function, quality of life, and survival in patients with Duchenne muscular dystrophy: a prospective cohort study

BACKGROUND

Glucocorticoid treatment is recommended as a standard of care in Duchenne muscular dystrophy; however, few studies have assessed the long-term benefits of this treatment. We examined the long-term effects of glucocorticoids on milestone-related disease progression across the lifespan and survival in patients with Duchenne muscular dystrophy.

METHODS

For this prospective cohort study, we enrolled male patients aged 2-28 years with Duchenne muscular dystrophy at 20 centres in nine countries. Patients were followed up for 10 years. We compared no glucocorticoid treatment or cumulative treatment duration of less than 1 month versus treatment of 1 year or longer with regard to progression of nine disease-related and clinically meaningful mobility and upper limb milestones. We used Kaplan-Meier analyses to compare glucocorticoid treatment groups for time to stand from supine of 5 s or longer and 10 s or longer, and loss of stand from supine, four-stair climb, ambulation, full overhead reach, hand-to-mouth function, and hand function. Risk of death was also assessed. This study is registered with ClinicalTrials.gov, number NCT00468832.

FINDINGS

440 patients were enrolled during two recruitment periods (2006-09 and 2012-16). Time to all disease progression milestone events was significantly longer in patients treated with glucocorticoids for 1 year or longer than in patients treated for less than 1 month or never treated (log-rank p<0·0001). Glucocorticoid treatment for 1 year or longer was associated with increased median age at loss of mobility milestones by 2·1-4·4 years and upper limb milestones by 2·8-8·0 years compared with treatment for less than 1 month. Deflazacort was associated with increased median age at loss of three milestones by 2·1-2·7 years in comparison with prednisone or prednisolone (log-rank p<0·012). 45 patients died during the 10-year follow-up. 39 (87%) of these deaths were attributable to Duchenne-related causes in patients with known duration of glucocorticoids usage. 28 (9%) deaths occurred in 311 patients treated with glucocorticoids for 1 year or longer compared with 11 (19%) deaths in 58 patients with no history of glucocorticoid use (odds ratio 0·47, 95% CI 0·22-1·00; p=0·0501).

INTERPRETATION

In patients with Duchenne muscular dystrophy, glucocorticoid treatment is associated with reduced risk of losing clinically meaningful mobility and upper limb disease progression milestones across the lifespan as well as reduced risk of death.

FUNDING

US Department of Education/National Institute on Disability and Rehabilitation Research; US Department of Defense; National Institutes of Health/National Institute of Arthritis and Musculoskeletal and Skin Diseases; and Parent Project Muscular Dystrophy.

A randomized placebo-controlled phase 3 trial of an antisense oligonucleotide, drisapersen, in Duchenne muscular dystrophy

This 48-week, randomized, placebo-controlled phase 3 study (DMD114044; NCT01254019) evaluated efficacy and safety of subcutaneous drisapersen 6 mg/kg/week in 186 ambulant boys aged ≥5 years, with Duchenne muscular dystrophy (DMD) resulting from an exon 51 skipping amenable mutation. Drisapersen was generally well tolerated, with injection-site reactions and renal events as most commonly reported adverse events. A nonsignificant treatment difference (P = 0.415) in the change from baseline in six-minute walk distance (6MWD; primary efficacy endpoint) of 10.3 meters in favor of drisapersen was observed at week 48. Key secondary efficacy endpoints (North Star Ambulatory Assessment, 4-stair climb ascent velocity, and 10-meter walk/run velocity) gave consistent findings. Lack of statistical significance was thought to be largely due to greater data variability and subgroup heterogeneity. The increased standard deviation alone, due to less stringent inclusion/exclusion criteria, reduced the statistical power from pre-specified 90% to actual 53%. Therefore, a post-hoc analysis was performed in 80 subjects with a baseline 6MWD 300-400 meters and ability to rise from floor. A statistically significant improvement in 6MWD of 35.4 meters (P = 0.039) in favor of drisapersen was observed in this subpopulation. Results suggest that drisapersen could have benefit in a less impaired population of DMD subjects.

Seeking a better landscape for therapy development in neuromuscular disorders

Although the neuromuscular field has seen accelerated approval of a drug for Duchenne muscular dystrophy (DMD) and full approval of one for spinal muscular atrophy, these experiences have shown that objective data and an adequate level of effect are essential for drug approval and reimbursement. The appropriateness and validity of biomarkers and clinically meaningful endpoints and an understanding of disease progression rates all played essential roles in the levels of evidence for these drugs. Such tools are best developed through integration of clinical data. The siloing of clinical data for rare neuromuscular diseases represents a considerable barrier to achieving better care and novel therapies for patients living with neuromuscular diseases. We discuss a data-sharing model implemented for DMD and urge cultural changes in the ways natural history and clinical trial data are collected and shared across all neuromuscular diseases in order to benefit the primary stakeholder, the patient. Muscle Nerve 57: 16-19, 2018.

Respiratory complications, management and treatments for neuromuscular disease in children

PURPOSE OF REVIEW

To summarize current literature describing the respiratory complications of neuromuscular disease (NMD) and the effect of respiratory interventions and to explore new gene therapies for patients with NMD.

RECENT FINDINGS

Measurements of respiratory function focus on vital capacity and maximal inspiratory and expiratory pressure and show decline over time. Management of respiratory complications includes lung volume recruitment, mechanical insufflation-exsufflation, chest physiotherapy and assisted ventilation. Lung volume recruitment can slow the progression of lung restriction. New gene-specific therapies for Duchenne muscular dystrophy and spinal muscular atrophy have the potential to preserve respiratory function longitudinally. However, the long-term therapeutic benefit remains unknown.

SUMMARY

Although NMDs are heterogeneous, many lead to progressive muscle weakness that compromises the function of the respiratory system including upper airway tone, cough and secretion clearance and chest wall support. Respiratory therapies augment or support the normal function of these components of the respiratory system. From a respiratory perspective, the new mutation and gene-specific therapies for NMD are likely to confer long-term therapeutic benefit. More sensitive and standard tools to assess respiratory function longitudinally are needed to monitor respiratory complications in children with NMD, particularly the youngest patients.

Identification of serum protein biomarkers for utrophin based DMD therapy

Despite promising therapeutic avenues, there is currently no effective treatment for Duchenne muscular dystrophy (DMD), a lethal monogenic disorder caused by the loss of the large cytoskeletal protein, dystrophin. A highly promising approach to therapy, applicable to all DMD patients irrespective to their genetic defect, is to modulate utrophin, a functional paralogue of dystrophin, able to compensate for the primary defects of DMD restoring sarcolemmal stability. One of the major difficulties in assessing the effectiveness of therapeutic strategies is to define appropriate outcome measures. In the present study, we utilised an aptamer based proteomics approach to profile 1,310 proteins in plasma of wild-type, mdx and Fiona (mdx overexpressing utrophin) mice. Comparison of the C57 and mdx sera revealed 83 proteins with statistically significant >2 fold changes in dystrophic serum abundance. A large majority of previously described biomarkers (ANP32B, THBS4, CAMK2A/B/D, CYCS, CAPNI) were normalised towards wild-type levels in Fiona animals. This work also identified potential mdx markers specific to increased utrophin (DUS3, TPI1) and highlights novel mdx biomarkers (GITR, MYBPC1, HSP60, SIRT2, SMAD3, CNTN1). We define a panel of putative protein mdx biomarkers to evaluate utrophin based strategies which may help to accelerate their translation to the clinic.