Leslie Nelson

Consensus statement on standard of care for congenital muscular dystrophies

Congenital muscular dystrophies are a group of rare neuromuscular disorders with a wide spectrum of clinical phenotypes. Recent advances in understanding the molecular pathogenesis of congenital muscular dystrophy have enabled better diagnosis. However, medical care for patients with congenital muscular dystrophy remains very diverse. Advances in many areas of medical technology have not been adopted in clinical practice. The International Standard of Care Committee for Congenital Muscular Dystrophy was established to identify current care issues, review literature for evidence-based practice, and achieve consensus on care recommendations in 7 areas: diagnosis, neurology, pulmonology, orthopedics/rehabilitation, gastroenterology/ nutrition/speech/oral care, cardiology, and palliative care. To achieve consensus on the care recommendations, 2 separate online surveys were conducted to poll opinions from experts in the field and from congenital muscular dystrophy families. The final consensus was achieved in a 3-day workshop conducted in Brussels, Belgium, in November 2009. This consensus statement describes the care recommendations from this committee.

The gross motor function measure™ is a valid and sensitive outcome measure for spinal muscular atrophy

Spinal muscular atrophy is a genetic disease of the anterior horn cell with high morbidity rate in childhood. Certain drugs may be of benefit and are in or under consideration for Phase II trials. Outcome measures that are age appropriate and representative of disease activity remain under study. Several have not yet been validated for spinal muscular atrophy. The Gross Motor Function Measure is a measure of motor function. We showed previously that the Gross Motor Function Measure is a reliable outcome measure to assess motor function in children with spinal muscular atrophy. By collating our data from 40 spinal muscular atrophy patients, ages 5 through 17 years, we now show the validity of the Gross Motor Function Measure when compared to Quantitative Muscle Testing and ambulatory status in children with spinal muscular atrophy. The median for Gross Motor Function Measure total scores for walkers was 237 (range: 197-261) and for non-walkers, 64 (range: 4-177; P<0.0001) with no distributional overlap. We conclude that the Gross Motor Function Measure is valid and sensitive as an outcome measure for clinical trials in pediatric spinal muscular atrophy.

The Test of Infant Motor Performance: Reliability in Spinal Muscular Atrophy Type I

Purpose: The aim of this article was to determine reliability of the Test of Infant Motor Performance (TIMP) in infants with spinal muscular atrophy, type I (SMA-I). Methods: Interrater reliability training was undertaken by 17 physical therapist evaluators using 6 infants with hypotonia and weakness (5 videotaped, 1 live). Eight trained evaluators then conducted a test-retest reliability study at their own center, performing 2 tests approximately 1 month apart on each of 11 infants with genetically confirmed SMA-I (5 boys, 6 girls; age range 37–501 days; 3 on pulmonary support). Results: The interrater reliability training session had an overall weighted &Kgr; of 0.61 (95% confidence interval 0.59–0.63). For the test-retest reliability study, the intraclass correlation coefficient for the TIMP Total Score was 0.85 (95% confidence interval: 0.54–0.96). The test scores were not significantly different between the 2 sessions (Bradley-Blackwood test was nonsignificant). Conclusion: TIMP scores can be reliably obtained in infants with SMA-I.

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.

RASCH ANALYSIS OF CLINICAL OUTCOME MEASURES IN SPINAL MUSCULAR ATROPHY

Introduction: Trial design for SMA depends on meaningful rating scales to assess outcomes. In this study Rasch methodology was applied to 9 motor scales in spinal muscular atrophy (SMA). Methods: Data from all 3 SMA types were provided by research groups for 9 commonly used scales. Rasch methodology assessed the ordering of response option thresholds, tests of fit, spread of item locations, residual correlations, and person separation index. Results: Each scale had good reliability. However, several issues impacting scale validity were identified, including the extent that items defined clinically meaningful constructs and how well each scale measured performance across the SMA spectrum. Conclusions: The sensitivity and potential utility of each SMA scale as outcome measures for trials could be improved by establishing clear definitions of what is measured, reconsidering items that misfit and items whose response categories have reversed thresholds, and adding new items at the extremes of scale ranges. Muscle Nerve 49:422–430, 2014

Diagnosis and management of spinal muscular atrophy: Part 1: Recommendations for diagnosis, rehabilitation, orthopedic and nutritional care

Spinal muscular atrophy (SMA) is a severe neuromuscular disorder due to a defect in the survival motor neuron 1 (SMN1) gene. Its incidence is approximately 1 in 11,000 live births. In 2007, an International Conference on the Standard of Care for SMA published a consensus statement on SMA standard of care that has been widely used throughout the world. Here we report a two-part update of the topics covered in the previous recommendations. In part 1 we present the methods used to achieve these recommendations, and an update on diagnosis, rehabilitation, orthopedic and spinal management; and nutritional, swallowing and gastrointestinal management. Pulmonary management, acute care, other organ involvement, ethical issues, medications, and the impact of new treatments for SMA are discussed in part 2.

Electrical impedance myography in individuals with collagen 6 and laminin α-2 congenital muscular dystrophy: a cross-sectional and 2-year analysis: EIM in COL6 and LAMA2 CMD

Electrical impedance myography (EIM) is a noninvasive electrophysiological technique that characterizes muscle properties through bioimpedance. We compared EIM measurements to function, strength, and disease severity in a population with congenital muscular dystrophy (CMD).

Prediction of Clinical Outcomes of Spinal Muscular Atrophy Using Motion Tracking Data and Elastic Net Regression

Spinal muscular atrophy (SMA) is a common muscle disease that can lead to high rate of infant mortality. It is important to be able to quickly and accurately diagnose SMAs as well as track disease progression throughout the treatment process. This study introduced a framework for deriving movement features from motion tracking data, and applied a regularized regression method to predict the gold standard clinical measures for SMA, the CHOP INTEND Extremities Scores (CIES). Our results showed the CIES could be predicted with good accuracy using derived motion features and Elastic Net regression. An RMSE of 8.5 points on CIES was achieved in both cross-validation and prediction on the held-out set. A high ROC-AUC of 0.91 was achieved for discriminating SMA infants from Controls on both session and subject levels. It was concluded that motion tracking devices could potentially be used as a low-cost yet effective method to assess and monitor infants with SMA.

Spinal Muscular Atrophy Clinical Trials: Lessons Learned

Abstract There are few completed randomized clinical trials for spinal muscular atrophy (SMA). There is no known effective treatment and most trials have been open label. However, much has been learned from those negative trials that helped improve trial design so that future studies will be powered and valid. Lessons learned include the fact that easy fatigability influences a subjects performance on outcome measures and that this fatigue can be induced by prolonged travel to the study site and prolonged procedures during the study visit. There is new and concerning use of social media by subjects and their families that could affect enrollment and outcomes; this demands new guidelines for trial participants and for investigators. Finally, it is very clear that all study groups must have received standard of care at the time of enrollment and throughout the study in order to avoid confounders of outcome measures.