Reliability of the Performance of Upper Limb assessment in Duchenne muscular dystrophy

Understanding adherence to noninvasive ventilation in youth with Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked, progressive neuromuscular disorder that results in chronic respiratory insufficiency and subsequently failure requiring noninvasive ventilation (NIV). Adherence to NIV in neuromuscular disorders and related barriers are poorly described. The aim of the current study was to assess NIV adherence, adherence barriers, and identify psychosocial predictors of adherence in young boys with early DMD-related sleep disordered breathing and recommended nocturnal NIV. This cross-sectional study included 42 youth with DMD with prescribed nocturnal NIV, and their caregivers. Caregivers and youth completed questionnaires assessing adherence barriers, psychosocial symptoms (eg, anxiety and depressive symptoms), and stress. Medical information pertinent to cardiopulmonary health and neurologic status at both enrollment and initiation of NIV was reviewed. Adherence to NIV, defined as percent days used and days used ≥4 hours/day was 56.1 ± 38.7% and 46.2 ± 40.6%, respectively. Average duration of use on days worn was 5.61 ± 4.23 hours. NIV usage was correlated with the severity of obstructive sleep apnea but not cardiopulmonary variables. Mask discomfort was the most commonly reported adherence barrier followed by behavioral barriers (eg, refusing to use). Multiple regression analyses revealed that internalizing behaviors (eg, anxiety and depressive symptoms) and total adherence barriers significantly predicted NIV adherence. Adherence to NIV in DMD is poor and similar to other pediatric chronic diseases. Our data suggest interventions targeting adherence barriers and patient internalizing symptoms may improve adherence to NIV in DMD.

Tamoxifen in Duchenne muscular dystrophy (TAMDMD): study protocol for a multicenter, randomized, placebo-controlled, double-blind phase 3 trial

Background

Duchenne muscular dystrophy (DMD) is an inherited neuromuscular disorder of childhood with a devastating disease course. Several targeted gene therapies and molecular approaches have been or are currently being tested in clinical trials; however, a causative therapy is still not available and best supportive care is limited to oral glucocorticoids with numerous long-term side effects. Tamoxifen is a selective estrogen receptor regulator, and shows antioxidant actions and regulatory roles in the calcium homeostasis besides its antitumor activity. In a mouse model of DMD, oral tamoxifen significantly improved muscle strength and reduced muscle fatigue. This multicenter, randomized, double-blind, placebo-controlled phase III trial aims to demonstrate safety and efficacy of tamoxifen over placebo in pediatric patients with DMD. After completion of the double-blind phase, an open-label extension of the study will be offered to all participants.

Methods/design

At least 71 ambulant and up to 20 nonambulant patients with DMD are planned to be enrolled at multiple European sites. Patients will be randomly assigned to receive either tamoxifen 20 mg or placebo daily over 48 weeks. In the open-label extension phase, all patients will be offered tamoxifen for a further 48 weeks. The primary endpoint of the double-blind phase is defined as the change of the D1 domain of the motor function measure in ambulant patients or a change of the D2 domain in nonambulant patients under tamoxifen compared to placebo. Secondary outcome measures include change in timed function tests, quantitative muscle testing, and quantitative magnetic resonance imaging of thigh muscles. Laboratory analyses including biomarkers of tamoxifen metabolism and muscle dystrophy will also be assessed.

Discussion

The aim of the study is to investigate whether tamoxifen can reduce disease progression in ambulant and nonambulant patients with DMD over 48 weeks. Motor function measures comprise the primary endpoint, whereas further clinical and radiological assessments and laboratory biomarkers are performed to provide more data on safety and efficacy. An adjacent open-label extension phase is planned to test if earlier initiation of the treatment with tamoxifen (verum arm of double-blind phase) compared to a delayed start can reduce disease progression more efficiently.

Trial registration

ClinicalTrials.gov, NCT03354039. Registered on 27 November 2017.

Monitoring daily physical activity of upper extremity in young and adolescent boys with Duchenne muscular dystrophy: A pilot study

INTRODUCTION

Accelerometry of the upper extremity (UE) potentially provides information on the extent of activities in daily life in patients with Duchenne muscular dystrophy (DMD). The objective of this study is to evaluate the validity of home measurements of UE accelerometry.

METHODS

This was a cross-sectional study in 16 patients with DMD (aged 7-17 years). Patients were monitored for 1 to 3 days with two accelerometers on the UE and one accelerometer on the wheelchair.

RESULTS

The mean intensity of activity and the mean frequency of transfers of arm elevation from low to middle were approximately twofold higher in patients with a Brooke scale score of 1 or 2 than in patients with a Brooke scale score of 3 or 4. Correlations with the Performance of Upper Limb scale score were high for intensity and for the total frequency of arm elevations per hour.

DISCUSSION

Intensity, percentage of time in middle orientation, and frequency of transfers of the upper arm correlated well with functional measurements.

Cumulative jerk as an outcome measure in nonambulatory Duchenne muscular dystrophy

OBJECTIVES

Quantitative or semiquantitative outcome measures for patients with Duchenne muscular dystrophy (DMD) are important, as they can be objective indicators of the natural history of DMD; these measures also aid in the evaluation of the efficacy of various treatments. However, the most widely used standard outcome measures in patients with DMD, such as the North Star Ambulatory Assessment and the 6-min walk test, cannot be applied after patients have become nonambulatory. We evaluated the utility and reliability of accelerometric analysis of motor activity in nonambulatory patients with DMD.

METHODS

We measured the motor activity of the upper extremity in 7 nonambulatory patients with DMD, by using an accelerometer attached at the wrist of the dominant arm. To eliminate gravitational acceleration, we measured the changes in acceleration between measurements. The root of the sum of squared values of the changes per unit time in the 3 axes of the accelerometer was defined as a jerk. The total sum of the jerk values obtained at a measurement frequency of 15.625 Hz for 8 h was defined as the cumulative sum of jerks (Cj).

RESULTS

The Cj values had significant and very strong or strong correlations with the Brooke Upper Extremity Scale (r_s = -0.973; p = 0.00023) and the arm function scores for the DMD Functional Ability Self-Assessment Tool (r_s = 0.810, p = 0.027). The values also had a very strong or strong correlation with the elbow flexion strength (nondominant arm: r = 0.931, p = 0.002; dominant arm: r = 0.750, p = 0.052).

CONCLUSION

Cj assessment is a useful method to evaluate motor activities in nonambulatory patients with DMD.

Respiratory and upper limb function as outcome measures in ambulant and non-ambulant subjects with Duchenne muscular dystrophy: A prospective multicentre study

The field of translational research in Duchenne muscular dystrophy (DMD) has been transformed in the last decade by a number of therapeutic targets, mostly studied in ambulant patients. A paucity of studies focus on measures that capture the non-ambulant stage of the disease, and the transition between the ambulant and non-ambulant phase. In this prospective natural history study, we report the results of a comprehensive assessment of respiratory, upper limb function and upper limb muscle strength in a group of 89 DMD boys followed in 3 European countries, 81 receiving corticosteroids, spanning a wide age range (5-18 years) and functional abilities, from ambulant (n = 60) to non-ambulant (n = 29). Respiratory decline could be detected in the early ambulatory phase using Peak Expiratory Flow percentage predicted (PEF%), despite glucocorticoid use (mean annual decline: 4.08, 95% CI [-7.44,-0.72], p = 0.02 in ambulant; 4.81, 95% CI [-6.79,-2.82], p < 0.001 in non-ambulant). FVC% captured disease progression in non-ambulant DMD subjects, with an annual loss of 5.47% (95% CI [-6.48,-4.45], p < 0.001). Upper limb function measured with the Performance of Upper Limb (PUL 1.2) showed an annual loss of 4.13 points (95% CI [-4.79,3.47], p < 0.001) in the non-ambulant cohort. Measures of upper limb strength (MyoGrip and MyoPinch) showed a continuous decline independent of the ambulatory status, when reported as percentage predicted (grip force -5.51%, 95% CI [-6.54,-4.48], p < 0.001 in ambulant and a slower decline -2.86%; 95% CI -3.29,-2.43, p < 0.001, in non-ambulant; pinch force: -2.66%, 95% CI [-3.82,-1.51], p < 0.001 in ambulant and -2.23%, 95% CI [-2.92,-1.53], p < 0.001 in non-ambulant). Furthermore, we also explored the novel concept of a composite endpoint by combining respiratory, upper limb function and force domains: we were able to identify clear clinical progression in patients in whom an isolated measurement of only one of these domains failed to appreciate the yearly change. Our study contributes to the field of natural history of DMD, linking the ambulant and non-ambulant phases of the disease, and suggests that composite scores should be explored further.

Cardiac and skeletal muscle effects in the randomized HOPE-Duchenne trial

OBJECTIVE

To assess the feasibility, safety, and efficacy of intracoronary allogeneic cardiosphere-derived cells (CAP-1002) in patients with Duchenne muscular dystrophy (DMD).

METHODS

The Halt Cardiomyopathy Progression (HOPE)-Duchenne trial is a phase I/II, randomized, controlled, open-label trial (NCT02485938). Patients with DMD >12 years old, with substantial myocardial fibrosis, were randomized (1:1) to usual care (control) or global intracoronary infusion of CAP-1002 (75 million cells). Participants were enrolled at 3 US medical centers between January and August 2016 and followed for 12 months. An independent Data and Safety Monitoring Board provided safety oversight. Cardiac function and structure were assessed by MRI, and analyzed by a blinded core laboratory. Skeletal muscle function was assessed by performance of the upper limb (PUL).

RESULTS

Twenty-five eligible patients (mean age 17.8 years; 68% wheelchair-dependent) were randomized to CAP-1002 (n = 13) or control (n = 12). Incidence of treatment-emergent adverse events was similar between groups. Compared to baseline, MRI at 12 months revealed significant scar size reduction and improvement in inferior wall systolic thickening in CAP-1002 but not control patients. Mid-distal PUL improved at 12 months in 8 of 9 lower functioning CAP-1002 patients, and no controls (p = 0.007).

CONCLUSIONS

Intracoronary CAP-1002 in DMD appears safe and demonstrates signals of efficacy on both cardiac and upper limb function for up to 12 months. Thus, future clinical research on CAP-1002 treatment of DMD cardiac and skeletal myopathies is warranted.

CLASSIFICATION OF EVIDENCE

This phase I/II study provides Class II evidence that for patients with DMD, intracoronary CAP-1002 is feasible and appears safe and potentially effective.

Virtual Reality Computer Gaming with Dynamic Arm Support in Boys with Duchenne Muscular Dystrophy

BACKGROUND

In boys with Duchenne muscular dystrophy (DMD), loss of upper limb function becomes more evident after the onset of wheelchair-dependency, because of the inability to lift the arms against gravity. With an increasing population of older wheelchair-dependent boys with DMD it is worthwhile to know whether training can delay the loss of upper limb functions. Dynamic arm supports may enable boys with impaired arm function to train their muscles without becoming exhausted by providing external mechanical compensation for muscle weakness.

OBJECTIVE

This study investigated the effect of gravity-compensated 3D-training for the arms on the functional abilities in boys with DMD.

METHODS

An explorative RCT was conducted among boys with DMD with impaired arm function (n = 16). Boys in the intervention group (n = 7) trained their arms by playing virtual reality games while using dynamic arm support during 20 weeks. The primary endpoint was the difference in change in Performance of the Upper Limb (PUL) score between the intervention and control group (n = 9) after 20 weeks. Secondary outcome measures were at the different ICF-CY levels.

RESULTS

No significant group differences were found for the PUL. Elbow range of motion (p = 0.018) and extension strength (p = 0.038) improved in the intervention group and worsened in the control group.

CONCLUSIONS

Although this study did not show a significant effect of training on the primary outcome measure, there are indications that training may decline the loss of range of motion and strength. This may prolong the functional abilities on long-term.

TRIAL REGISTRATION

Netherlands Trial Register 3857.

Upper limb function in Duchenne muscular dystrophy: 24 month longitudinal data

The aim of the study was to establish 24 month changes in upper limb function using a revised version of the performance of upper limb test (PUL 2.0) in a large cohort of ambulant and non-ambulant boys with Duchenne muscular dystrophy and to identify possible trajectories of progression. Of the 187 patients studied, 87 were ambulant (age range: 7–15.8 years), and 90 non-ambulant (age range: 9.08–24.78). The total scores changed significantly over time (p<0.001). Non-ambulant patients had lower total scores at baseline (mean 19.7) when compared to the ambulant ones (mean 38.4). They also had also a bigger decrease in total scores over 24 months compared to the ambulant boys (4.36 vs 2.07 points). Multivariate model analysis showed that the Performance of Upper Limb changes reflected the entry level and ambulation status, that were independently associated to the slope of Performance of Upper Limb changes. This information will be of help both in clinical practice and at the time of designing clinical trials.

Functional levels and MRI patterns of muscle involvement in upper limbs in Duchenne muscular dystrophy

The aim of the study was to evaluate the spectrum of upper limb functional activities and imaging finding in a cohort of patients affected by Duchenne muscular dystrophy. Thirty-one patients of age between 5 and 29 years were included in the study (17 ambulant and 14 non-ambulant). They were all assessed using the Performance of Upper Limb (PUL) test and muscle MRI of shoulder, arm and forearm in order to establish if the functional scores obtained at shoulder, mid and distal level related to specific patterns of involvement in each upper limb segment on muscle MRI. At shoulder level, latissimus dorsi, serratus anterior, infraspinatus and subscapularis were always involved, even in patients with full functional scores at shoulder level. Diffuse and severe involvement of all muscles was found in the patients with a PUL shoulder functional score of ≤ 5. At arm level biceps brachii, brachialis and triceps were generally concordantly involved or spared. Some degree of involvement could already be detected in patients with reduced scores on the PUL mid domain. They were generally severely involved in patients with functional scores less than 6 at mid-level. At distal level supinator and pronator muscles were often involved, followed by brachioradialis and, less frequently, by the muscles of the flexor compartment. The extensor muscles were generally completely spared. A diffuse and severe involvement was found only in patients who had very low scores (8 or below) on the PUL distal domain. The integrated use of functional scales and imaging allowed to establish patterns of involvement at each level, and the functional scores that were more frequently associated with diffuse and severe involvement.

Skeletal muscle magnetic resonance biomarkers correlate with function and sentinel events in Duchenne muscular dystrophy

OBJECTIVE

To provide evidence for quantitative magnetic resonance (qMR) biomarkers in Duchenne muscular dystrophy by investigating the relationship between qMR measures of lower extremity muscle pathology and functional endpoints in a large ambulatory cohort using a multicenter study design.

METHODS

MR spectroscopy and quantitative imaging were implemented to measure intramuscular fat fraction and the transverse magnetization relaxation time constant (T2) in lower extremity muscles of 136 participants with Duchenne muscular dystrophy. Measures were collected at 554 visits over 48 months at one of three imaging sites. Fat fraction was measured in the soleus and vastus lateralis using MR spectroscopy, while T2 was assessed using MRI in eight lower extremity muscles. Ambulatory function was measured using the 10m walk/run, climb four stairs, supine to stand, and six minute walk tests.

RESULTS

Significant correlations were found between all qMR and functional measures. Vastus lateralis qMR measures correlated most strongly to functional endpoints (|ρ| = 0.68-0.78), although measures in other rapidly progressing muscles including the biceps femoris (|ρ| = 0.63-0.73) and peroneals (|ρ| = 0.59-0.72) also showed strong correlations. Quantitative MR biomarkers were excellent indicators of loss of functional ability and correlated with qualitative measures of function. A VL FF of 0.40 was an approximate lower threshold of muscle pathology associated with loss of ambulation.

DISCUSSION

Lower extremity qMR biomarkers have a robust relationship to clinically meaningful measures of ambulatory function in Duchenne muscular dystrophy. These results provide strong supporting evidence for qMR biomarkers and set the stage for their potential use as surrogate outcomes in clinical trials.

Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and neuromuscular, rehabilitation, endocrine, and gastrointestinal and nutritional management

Since the publication of the Duchenne muscular dystrophy (DMD) care considerations in 2010, multidisciplinary care of this severe, progressive neuromuscular disease has evolved. In conjunction with improved patient survival, a shift to more anticipatory diagnostic and therapeutic strategies has occurred, with a renewed focus on patient quality of life. In 2014, a steering committee of experts from a wide range of disciplines was established to update the 2010 DMD care considerations, with the goal of improving patient care. The new care considerations aim to address the needs of patients with prolonged survival, to provide guidance on advances in assessments and interventions, and to consider the implications of emerging genetic and molecular therapies for DMD. The committee identified 11 topics to be included in the update, eight of which were addressed in the original care considerations. The three new topics are primary care and emergency management, endocrine management, and transitions of care across the lifespan. In part 1 of this three-part update, we present care considerations for diagnosis of DMD and neuromuscular, rehabilitation, endocrine (growth, puberty, and adrenal insufficiency), and gastrointestinal (including nutrition and dysphagia) management.

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.

Leveraging pediatric PROMIS item banks to assess physical functioning in children at risk for severe functional loss

Background

Pediatric neuromuscular illnesses often result in decreased health-related quality of life (HRQL), notably in physical functioning. Generic HRQL measures have been developed for use in general populations, but may not adequately assess patients with severe functional loss. To address this measurement gap, we created two custom parent-proxy physical functioning short forms for use among children at risk for low levels of functioning, using pediatric Patient Reported Outcomes Measurement Information System (PROMIS) item banks for Upper Extremity and Mobility.

Methods

Two custom short forms from PROMIS Upper Extremity (13 items) and Mobility (13 items) parent-proxy item banks were created and administered to parents of children (ages 5 - 22 years) enrolled in an integrated care program for management of chronic respiratory insufficiency, largely due to neuromuscular illnesses. Standardized PROMIS T-scores have a mean of 50 (SD = 10); higher scores indicate better functioning. Physicians rated clinical severity. Single proxy-rated items on mental and physical health from the Child Health Rating Inventories (CHRIs) global health scale were completed by parents. Psychometric properties, including known groups comparisons, were explored.

Results

Fifty-seven parents completed the parent-proxy custom PROMIS short forms. The mean Upper Extremity T-score was 21 (SD = 13); the mean Mobility T-score was 22 (SD = 11). Some participants scored at the measurement floor; two items on assistive devices did not perform well in this sample and were excluded from the Mobility T-score. Known groups comparisons showed that those with lower clinical severity had better median Upper Extremity (22 vs. 14, p < 0.001) and Mobility (28 vs. 16, p = 0.004) function than those with worse clinical severity. Both Upper Extremity and Mobility T-scores were higher in the subgroups defined by better physical and mental health, as measured by the CHRIs.

Conclusions

Upper Extremity and Mobility T-scores were nearly three standard deviations below the PROMIS pediatric calibration population mean. Preliminary psychometrics demonstrated the potential to more accurately measure lower physical functioning using items from PROMIS item banks. However, some participants scored at the measurement floor despite targeting items at the lower end of the scale. Further short form refinement, enrichment of the item banks, and larger-scale field testing are needed.

A phase 3 randomized placebo-controlled trial of tadalafil for Duchenne muscular dystrophy

OBJECTIVE

To conduct a randomized trial to test the primary hypothesis that once-daily tadalafil, administered orally for 48 weeks, lessens the decline in ambulatory ability in boys with Duchenne muscular dystrophy (DMD).

METHODS

Three hundred thirty-one participants with DMD 7 to 14 years of age taking glucocorticoids were randomized to tadalafil 0.3 mg·kg^-1·d^-1, tadalafil 0.6 mg·kg^-1·d^-1, or placebo. The primary efficacy measure was 6-minute walk distance (6MWD) after 48 weeks. Secondary efficacy measures included North Star Ambulatory Assessment and timed function tests. Performance of Upper Limb (PUL) was a prespecified exploratory outcome.

RESULTS

Tadalafil had no effect on the primary outcome: 48-week declines in 6MWD were 51.0 ± 9.3 m with placebo, 64.7 ± 9.8 m with low-dose tadalafil (p = 0.307 vs placebo), and 59.1 ± 9.4 m with high-dose tadalafil (p = 0.538 vs placebo). Tadalafil also had no effect on secondary outcomes. In boys >10 years of age, total PUL score and shoulder subscore declined less with low-dose tadalafil than placebo. Adverse events were consistent with the known safety profile of tadalafil and the DMD disease state.

CONCLUSIONS

Tadalafil did not lessen the decline in ambulatory ability in boys with DMD. Further studies should be considered to confirm the hypothesis-generating upper limb data and to determine whether ambulatory decline can be slowed by initiation of tadalafil before 7 years of age.

CLINICALTRIALSGOV IDENTIFIER

NCT01865084.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that tadalafil does not slow ambulatory decline in 7- to 14-year-old boys with Duchenne muscular dystrophy.

[Upper limb functional assessment scale for children with Duchenne muscular dystrophy and Spinal muscular atrophy]

Duchenne muscular dystrophy (DMD) and Spinal muscular atrophy (SMA) causes significant disability and progressive functional impairment. Readily available instruments that assess functionality, especially in advanced stages of the disease, are required to monitor the progress of the disease and the impact of therapeutic interventions.

OBJECTIVE

To describe the development of a scale to evaluate upper limb function (UL) in patients with DMD and SMA, and describe its validation process, which includes self-training for evaluators.

PATIENTS AND METHOD

The development of the scale included a review of published scales, an exploratory application of a pilot scale in healthy children and those with DMD, self-training of evaluators in applying the scale using a handbook and video tutorial, and assessment of a group of children with DMD and SMA using the final scale. Reliability was assessed using Cronbach and Kendall concordance and with intra and inter-rater test-retest, and validity with concordance and factorial analysis.

RESULTS

A high level of reliability was observed, with high internal consistency (Cronbach a = 0.97), and inter-rater (Kendall W = 0.96) and intra-rater concordance (r = 0.97 to 0.99). The validity was demonstrated by the absence of significant differences between results by different evaluators with an expert evaluator (F = 0.023, p > .5), and by the factor analysis that showed that four factors account for 85.44% of total variance.

CONCLUSIONS

This scale is a reliable and valid tool for assessing UL functionality in children with DMD and SMA. It is also easily implementable due to the possibility of self-training and the use of simple and inexpensive materials.

Ataluren in patients with nonsense mutation Duchenne muscular dystrophy (ACT DMD): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Duchenne muscular dystrophy (DMD) is a severe, progressive, and rare neuromuscular, X-linked recessive disease. Dystrophin deficiency is the underlying cause of disease; therefore, mutation-specific therapies aimed at restoring dystrophin protein production are being explored. We aimed to assess the efficacy and safety of ataluren in ambulatory boys with nonsense mutation DMD.

METHODS

We did this multicentre, randomised, double-blind, placebo-controlled, phase 3 trial at 54 sites in 18 countries located in North America, Europe, the Asia-Pacific region, and Latin America. Boys aged 7-16 years with nonsense mutation DMD and a baseline 6-minute walk distance (6MWD) of 150 m or more and 80% or less of the predicted normal value for age and height were randomly assigned (1:1), via permuted block randomisation (block size of four) using an interactive voice-response or web-response system, to receive ataluren orally three times daily (40 mg/kg per day) or matching placebo. Randomisation was stratified by age (<9 years vs ≥9 years), duration of previous corticosteroid use (6 months to <12 months vs ≥12 months), and baseline 6MWD (<350 m vs ≥350 m). Patients, parents and caregivers, investigational site personnel, PTC Therapeutics employees, and all other study personnel were masked to group allocation until after database lock. The primary endpoint was change in 6MWD from baseline to week 48. We additionally did a prespecified subgroup analysis of the primary endpoint, based on baseline 6MWD, which is reflective of anticipated rates of disease progression over 1 year. The primary analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01826487.

FINDINGS

Between March 26, 2013, and Aug 26, 2014, we randomly assigned 230 patients to receive ataluren (n=115) or placebo (n=115); 228 patients comprised the intention-to-treat population. The least-squares mean change in 6MWD from baseline to week 48 was -47·7 m (SE 9·3) for ataluren-treated patients and -60·7 m (9·3) for placebo-treated patients (difference 13·0 m [SE 10·4], 95% CI -7·4 to 33·4; p=0·213). The least-squares mean change for ataluren versus placebo in the prespecified subgroups was -7·7 m (SE 24·1, 95% CI -54·9 to 39·5; p=0·749) in the group with a 6MWD of less than 300 m, 42·9 m (15·9, 11·8-74·0; p=0·007) in the group with a 6MWD of 300 m or more to less than 400 m, and -9·5 m (17·2, -43·2 to 24·2; p=0·580) in the group with a 6MWD of 400 m or more. Ataluren was generally well tolerated and most treatment-emergent adverse events were mild to moderate in severity. Eight (3%) patients (n=4 per group) reported serious adverse events; all except one event in the placebo group (abnormal hepatic function deemed possibly related to treatment) were deemed unrelated to treatment.

INTERPRETATION

Change in 6MWD did not differ significantly between patients in the ataluren group and those in the placebo group, neither in the intention-to-treat population nor in the prespecified subgroups with a baseline 6MWD of less than 300 m or 400 m or more. However, we recorded a significant effect of ataluren in the prespecified subgroup of patients with a baseline 6MWD of 300 m or more to less than 400 m. Baseline 6MWD values within this range were associated with a more predictable rate of decline over 1 year; this finding has implications for the design of future DMD trials with the 6-minute walk test as the endpoint.

FUNDING

PTC Therapeutics.

Development of a patient-reported outcome measure for upper limb function in Duchenne muscular dystrophy: DMD Upper Limb PROM

AIM

To develop a patient-reported outcome measure (PROM) assessing upper limb function related to activities of daily living (ADL) that cannot be observed in a clinical setting, specifically for patients with Duchenne muscular dystrophy (DMD) across a wide age range, applicable in the different stages of the disease.

METHOD

The developmental process was based on US Food and Drug Administration guidelines. This included item generation from a systematic review of existing tools and expert opinion on task difficulty and relevance, involving individuals with DMD. Cultural aspects affecting ADL were taken into consideration to make this tool applicable to the broad DMD community. Items were selected in relation to a conceptual framework reflecting disease progression covering the full range of upper limb function across different ADL domains.

RESULTS

After pilot testing and iterative Rasch analyses, redundant or clinically irrelevant items were removed. The final questionnaire consists of 32 items covering four domains of ADL (food, self-care, household and environment, leisure and communication). Test-retest reliability was excellent.

INTERPRETATION

A DMD-specific upper limb PROM was developed on the basis of clinical relevance and psychometric robustness. Its main purpose is to document the patient self-reported natural history of DMD and assess the efficacy of interventions.

Hand Function in Muscular Dystrophies

The aim of this study was to investigate the relationship between Performance of Upper Limb (PUL) and Jebsen–Taylor Test (JTT) to assess and monitor upper limb function progression in patients with muscular dystrophy. Thirty patients diagnosed with Duchenne muscular dystrophy, limb-girdle muscular dystrophy, Becker muscular dystrophy, myotonic dystrophy Type 1, and fascioscapulohumeral dystrophy were submitted to the shoulder, elbow, and wrist domains of PUL, and to JTT subtests. Spearman tests investigated the relationships between PUL and JTT total scores and domains. Correlations were classified as strong ( r ≥ 0.70), moderate (0.40 ≤  r < 0.70), or weak ( r ≤ 0.40). There were strong correlations between the PUL and JTT total scores ( r = −0.706). Although JTT measures time and PUL provides kinesiologic scores, these measures were related. Therefore, muscle synergies, which control the compensatory movements and motor functions involving mainly shoulder, elbow, wrist, and finger movements, are related to timed performance in patients with muscular dystrophies.

Exon skipping: a first in class strategy for Duchenne muscular dystrophy

INTRODUCTION

Exon skipping is a therapeutic approach for Duchenne muscular dystrophy (DMD) that has been in development for close to two decades. This approach uses antisense oligonucleotides (AONs) to modulate pre-mRNA splicing of dystrophin transcripts to restore the disrupted DMD reading frame. The approach has moved from in vitro proof of concept studies to the clinical trial phase and marketing authorization applications with regulators. The first AON (eteplirsen) has recently received accelerated approval by the Food and Drug Administration in the US. Areas covered: In this review the authors explain the antisense-mediated exon skipping approach, outline how it needs be tailored for different DMD mutation types and describe the challenges and opportunities for each mutation type. The authors summarize the clinical development of antisense-mediated exon 51 skipping, and discuss methods to improve efficiency. Finally, the authors provide their opinion on current developments and identify topics for future prioritization. Expert opinion: Exon skipping development has been a learning experience for all those involved. Aside from an approved therapy, its development has yielded side benefits including the development of tools for clinical trials and has increased collaboration between academics, patients, industry and regulators.

Magnetic resonance imaging of the proximal upper extremity musculature in boys with Duchenne muscular dystrophy

There is a pressing need for biomarkers and outcomes that can be used across disease stages in Duchenne muscular dystrophy (DMD), to facilitate the inclusion of a wider range of participants in clinical trials and to improve our understanding of the natural history of DMD. Quantitative magnetic resonance imaging (qMRI) and spectroscopy (MRS) biomarkers show considerable promise in both the legs and forearms of individuals with DMD, but have not yet been examined in functionally important proximal upper extremity muscles such as the biceps brachii and deltoid. The primary objective of this study was to examine the feasibility of implementing qMRI and MRS biomarkers in the proximal upper extremity musculature, and the secondary objective was to examine the relationship between MR measures of arm muscle pathology and upper extremity functional endpoints. Biomarkers included MRS and MRI measures of fat fraction and transverse relaxation time (T ₂). The MR exam was well tolerated in both ambulatory and non-ambulatory boys. qMR biomarkers differentiated affected and unaffected participants and correlated strongly with upper extremity function (r = 0.91 for biceps brachii T ₂ versus performance of upper limb score). These qMR outcome measures could be highly beneficial to the neuromuscular disease community, allowing measurement of the quality of functionally important muscles across disease stages to understand the natural history of DMD and particularly to broaden the opportunity for clinical trial participation.

Upper Limb Evaluation in Duchenne Muscular Dystrophy: Fat-Water Quantification by MRI, Muscle Force and Function Define Endpoints for Clinical Trials

Objective

A number of promising experimental therapies for Duchenne muscular dystrophy (DMD) are emerging. Clinical trials currently rely on invasive biopsies or motivation-dependent functional tests to assess outcome. Quantitative muscle magnetic resonance imaging (MRI) could offer a valuable alternative and permit inclusion of non-ambulant DMD subjects. The aims of our study were to explore the responsiveness of upper-limb MRI muscle-fat measurement as a non-invasive objective endpoint for clinical trials in non-ambulant DMD, and to investigate the relationship of these MRI measures to those of muscle force and function.

Methods

15 non-ambulant DMD boys (mean age 13.3 y) and 10 age-gender matched healthy controls (mean age 14.6 y) were recruited. 3-Tesla MRI fat-water quantification was used to measure forearm muscle fat transformation in non-ambulant DMD boys compared with healthy controls. DMD boys were assessed at 4 time-points over 12 months, using 3-point Dixon MRI to measure muscle fat-fraction (f.f.). Images from ten forearm muscles were segmented and mean f.f. and cross-sectional area recorded. DMD subjects also underwent comprehensive upper limb function and force evaluation.

Results

Overall mean baseline forearm f.f. was higher in DMD than in healthy controls (p<0.001). A progressive f.f. increase was observed in DMD over 12 months, reaching significance from 6 months (p<0.001, n = 7), accompanied by a significant loss in pinch strength at 6 months (p<0.001, n = 9) and a loss of upper limb function and grip force observed over 12 months (p<0.001, n = 8).

Conclusions

These results support the use of MRI muscle f.f. as a biomarker to monitor disease progression in the upper limb in non-ambulant DMD, with sensitivity adequate to detect group-level change over time intervals practical for use in clinical trials. Clinical validity is supported by the association of the progressive fat transformation of muscle with loss of muscle force and function.

Long-Term Efficacy, Safety, and Pharmacokinetics of Drisapersen in Duchenne Muscular Dystrophy: Results from an Open-Label Extension Study

Background

Drisapersen induces exon 51 skipping during dystrophin pre-mRNA splicing and allows synthesis of partially functional dystrophin in Duchenne muscular dystrophy (DMD) patients with amenable mutations.

Methods

This 188-week open-label extension of the dose-escalation study assessed the long-term efficacy, safety, and pharmacokinetics of drisapersen (PRO051/GSK2402968), 6 mg/kg subcutaneously, in 12 DMD subjects. Dosing was once weekly for 72 weeks. All subjects had a planned treatment interruption (weeks 73–80), followed by intermittent dosing (weeks 81–188).

Results

Subjects received a median (range) total dose of 5.93 (5.10 to 6.02) mg/kg drisapersen. After 177 weeks (last efficacy assessment), median (mean [SD]) six-minute walk distance (6MWD) improved by 8 (-24.5 [161]) meters for the 10 subjects able to complete the 6MWD at baseline (mean age [SD]: 9.5 [1.9] years). These statistics include 2 subjects unable to complete the test at later visits and who scored “zero”. When only the 8 ambulant subjects at week 177 were taken into account, a median (mean [SD]) increase of 64 (33 [121]) meters in 6MWD was observed. Of 7 subjects walking ≥330 m at extension baseline, 5 walked farther at week 177. Of 3 subjects walking <330 m, 2 lost ambulation, while 1 declined overall but walked farther at some visits. Over the 188 weeks, the most common adverse events were injection-site reactions, raised urinary α₁-microglobulin and proteinuria. Dystrophin expression was detected in all muscle biopsies obtained at week 68 or 72.

Conclusion

Drisapersen was generally well tolerated over 188 weeks. Possible renal effects, thrombocytopenia and injection-site reactions warrant continued monitoring. Improvements in the 6MWD at 12 weeks were sustained after 3.4 years of dosing for most patients. For a small, uncontrolled study, the outcomes are encouraging, as natural history studies would anticipate a decline of over 100 meters over a 3-year period in a comparable cohort.

Trial Registration

ClinicalTrials.gov NCT01910649

Reachable workspace and performance of upper limb (PUL) in duchenne muscular dystrophy

INTRODUCTION

The Kinect-based reachable workspace relative surface area (RSA) is compared with the performance of upper limb (PUL) assessment in Duchenne muscular dystrophy (DMD).

METHODS

29 individuals with DMD (ages: 7-23; Brooke: 1-5) underwent both Kinect-based reachable workspace RSA and PUL assessments. RSAs were also collected from 24 age-matched controls. Total and quadrant RSAs were compared with the PUL total, shoulder-, middle-, and distal-dimension scores.

RESULTS

The total reachable workspace RSA correlated well with the total PUL score (Spearman ρ = -0.602; P < 0.001), and with each of the PUL dimensional scores: shoulder (ρ = -0.624; P < 0.001), middle (ρ = -0.564; P = 0.001), and distal (ρ = -0.630; P < 0.001). With quadrant RSA, reachability in a particular quadrant was closely associated with respective PUL dimensional-level function (lateral-upper quadrant for shoulder-, lateral-upper/lower quadrants for middle-, and lateral-lower quadrant for distal-level function).

CONCLUSIONS

This study demonstrates concurrent validity of the reachable workspace outcome measure (RSA) with the DMD-specific upper extremity outcome measure (PUL).

The Performance of the Upper Limb scores correlate with pulmonary function test measures and Egen Klassifikation scores in Duchenne muscular dystrophy

The Performance of the Upper Limb scale was developed as an outcome measure specifically for ambulant and non-ambulant patients with Duchenne muscular dystrophy and is implemented in clinical trials needing longitudinal data. The aim of this study is to determine whether this novel tool correlates with functional ability using pulmonary function test, cardiac function test and Egen Klassifikation scale scores as clinical measures. In this cross-sectional study, 43 non-ambulatory Duchenne males from ages 10 to 30 years and on long-term glucocorticoid treatment were enrolled. Cardiac and pulmonary function test results were analyzed to assess cardiopulmonary function, and Egen Klassifikation scores were analyzed to assess functional ability. The Performance of the Upper Limb scores correlated with pulmonary function measures and had inverse correlation with Egen Klassifikation scores. There was no correlation with left ventricular ejection fraction and left ventricular dysfunction. Body mass index and decreased joint range of motion affected total Performance of the Upper Limb scores and should be considered in clinical trial designs.

Multicenter prospective longitudinal study of magnetic resonance biomarkers in a large duchenne muscular dystrophy cohort

OBJECTIVE

The aim of this study was to describe Duchenne muscular dystrophy (DMD) disease progression in the lower extremity muscles over 12 months using quantitative magnetic resonance (MR) biomarkers, collected across three sites in a large cohort.

METHODS

A total of 109 ambulatory boys with DMD (8.7 ± 2.0 years; range, 5.0-12.9) completed baseline and 1-year follow-up quantitative MR imaging (transverse relaxation time constant; MRI-T2 ), MR spectroscopy (fat fraction and (1) H2 O T2 ), and 6-minute walk test (6MWT) measurements. A subset of boys completed additional measurements after 3 or 6 months.

RESULTS

MRI-T2 and fat fraction increased significantly over 12 months in all age groups, including in 5- to 6.9-year-old boys. Significant increases in vastus lateralis (VL) fat fraction were observed in 3 and 6 months. Even in boys whose 6MWT performance improved or remained stable over 1 year, significant increases in MRI-T2 and fat fraction were found. Of all the muscles examined, the VL and biceps femoris long head were the most responsive to disease progression in boys with DMD.

INTERPRETATION

MR biomarkers are responsive to disease progression in 5- to 12.9-year-old boys with DMD and able to detect subclinical disease progression in DMD, even within short (3-6 months) time periods. The measured sensitivity of MR biomarkers in this multicenter study may be critically important to future clinical trials, allowing for smaller sample sizes and/or shorter study windows in this fatal rare disease.

Benefits of glucocorticoids in non-ambulant boys/men with Duchenne muscular dystrophy: A multicentric longitudinal study using the Performance of Upper Limb test

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The paper reports the effect of steroids on upper limb function in non ambulant DMD boys.

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Boys continuing steroids after loss of ambulation perform better than those who stopped at the time of loss of ambulation.

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The Performance of Upper Limb test can reliably capture change over time and the effect of intervention.

The aim of this study was to establish the possible effect of glucocorticoid treatment on upper limb function in a cohort of 91 non-ambulant DMD boys and adults of age between 11 and 26 years.

All 91 were assessed using the Performance of Upper Limb test. Forty-eight were still on glucocorticoid after loss of ambulation, 25 stopped steroids at the time they lost ambulation and 18 were GC naïve or had steroids while ambulant for less than a year.

At baseline the total scores ranged between 0 and 74 (mean 41.20). The mean total scores were 47.92 in the glucocorticoid group, 36 in those who stopped at loss of ambulation and 30.5 in the naïve group (p < 0.001).

The 12-month changes ranged between −20 and 4 (mean −4.4). The mean changes were −3.79 in the glucocorticoid group, −5.52 in those who stopped at loss of ambulation and −4.44 in the naïve group. This was more obvious in the patients between 12 and 18 years and at shoulder and elbow levels.

Our findings suggest that continuing glucocorticoids throughout teenage years and adulthood after loss of ambulation appears to have a beneficial effect on upper limb function.

Reliability and validity of active-seated: An outcome in dystrophinopathy

INTRODUCTION

Traditional upper extremity measures typically focus on distal abilities and do not quantify the unique progression of decline in dystrophinopathy. We designed ACTIVE-seated to meet this need. Our objective was to establish the tool's validity and reliability.

METHODS

ACTIVE-seated uses the Microsoft Kinect gaming interface to quantify functional reaching ability while playing a custom-designed game. A skeletal tracking algorithm was used to determine the furthest arm excursion in all planes in 61 subjects with dystrophinopathy and 16 controls.

RESULTS

Total reachable area was scaled based on arm length to standardize comparisons across subjects and accommodate growth. ACTIVE-seated discriminately ranked subjects from normal controls and by Brooke level (P < 0.001). Scores were highly correlated with parent reports of daily activities and mobility (P < 0.05). Test-retest reliability of ACTIVE-seated was excellent (ICC = 0.97, P < 0.0001).

CONCLUSIONS

Initial evaluation of reliability and validity suggests that ACTIVE-seated shows promise as a clinical and research outcome for individuals with dystrophinopathy.

Disease course in mdx:utrophin+/- mice: comparison of three mouse models of Duchenne muscular dystrophy

The mdx mouse model of Duchenne muscular dystrophy (DMD) is used to study disease mechanisms and potential treatments, but its pathology is less severe than DMD patients. Other mouse models were developed to more closely mimic the human disease based on knowledge that upregulation of utrophin has a protective effect in mdx muscle. An mdx:utrophin^−/− (dko) mouse was created, which had a severe disease phenotype and a shortened life span. An mdx:utrophin^+/− mouse was also created, which had an intermediate disease phenotype compared to the mdx and dko mice. To determine the usefulness of mdx:utrophin^+/− mice for long-term DMD studies, limb muscle pathology and function were assessed across the life span of wild-type, mdx, mdx:utrophin^+/−, and dko mice. Muscle function assessment, specifically grip duration and rotarod performance, demonstrated that mdx:utrophin^+/− mice were weaker for a longer time than mdx mice. Mean myofiber area was smaller in mdx:utrophin^+/− mice compared to mdx mice at 12 months. Mdx:utrophin^+/− mice had a higher percentage of centrally nucleated myofibers compared to mdx mice at 6 and 12 months. Collagen I and IV density was significantly higher in mdx:utrophin^+/− muscle compared to mdx at most ages examined. Generally, mdx:utrophin^+/− mice showed an intermediate disease phenotype over a longer time course compared to the mdx and dko mice. While they do not genetically mirror human DMD, mdx:utrophin^+/− mice may be a more useful animal model than mdx or dko mice for investigating long-term efficacy of potential treatments when fibrosis or muscle function is the focus.

Upper limb strength and function changes during a one-year follow-up in non-ambulant patients with Duchenne Muscular Dystrophy: an observational multicenter trial

Introduction

Upper limb evaluation of patients with Duchenne Muscular Dystrophy is crucially important to evaluations of efficacy of new treatments in non-ambulant patients. In patients who have lost ambulation, there are few validated and informative outcome measures. In addition, longitudinal data demonstrating sensitivity to clinical evolution of outcome measures over short-term periods are lacking.

Patients and Methods

We report here the results of a one-year multicenter study using specifically designed tools to assess grip, pinch strength, and hand function in wheelchair-bound patients. Our study assessed 53 non-ambulant patients with Duchenne muscular dystrophy aged 17.1 ± 4.8 years (range: 9 – 28.1 years). The average Brooke functional score of these patients was 4.6 ± 1.1. The average forced vital capacity was 44.5% predicted and 19 patients used non-invasive ventilation. Patients were assessed at baseline, 6 months, and one year using the Motor Function Measure and innovative devices (namely the MyoSet composed of MyoGrip, MyoPinch, and MoviPlate).

Results

Our study confirmed preliminary data previously reported regarding feasibility of use and of reliability of the MyoSet and the correlation at baseline between distal strength and clinical outcomes such as FVC, Brooke score, age, and duration since loss of ambulation. A significant correlation was observed between the distal upper limb strength and clinical variables. The sensitive dynamometers (MyoGrip and MyoPinch) and MoviPlate captured a 12-month change in non-ambulant Duchenne muscular dystrophy patients of all ages.

Trial Registration

ClinicalTrials.gov NCT00993161 NCT00993161

The 6 minute walk test and performance of upper limb in ambulant duchenne muscular dystrophy boys

The Performance of Upper Limb (PUL) test was specifically developed for the assessment of upper limbs in Duchenne muscular dystrophy (DMD). The first published data have shown that early signs of involvement can also be found in ambulant DMD boys. The aim of this longitudinal Italian multicentric study was to evaluate the correlation between the 6 Minute Walk Test (6MWT) and the PUL in ambulant DMD boys. Both 6MWT and PUL were administered to 164 ambulant DMD boys of age between 5.0 and 16.17 years (mean 8.82). The 6 minute walk distance (6MWD) ranged between 118 and 557 (mean: 376.38, SD: 90.59). The PUL total scores ranged between 52 and 74 (mean: 70.74, SD: 4.66). The correlation between the two measures was 0.499. The scores on the PUL largely reflect the overall impairment observed on the 6MWT but the correlation was not linear. The use of the PUL appeared to be less relevant in the very strong patients with 6MWD above 400 meters, who, with few exceptions had near full scores. In patients with lower 6MWD the severity of upper limb involvement was more variable and could not always be predicted by the 6MWD value or by the use of steroids. Our results confirm that upper limb involvement can already be found in DMD boys even in the ambulant phase.