Factors Associated With Early Motor Function Trajectories in DMD After Glucocorticoid Initiation: Post Hoc Analysis of the FOR-DMD Trial

BACKGROUND AND OBJECTIVES

Clinical trials in Duchenne muscular dystrophy (DMD) require 3-6 months of stable glucocorticoids, and the primary outcome is explored at 48-52 weeks. The factors that influence the clinical outcome assessment (COA) trajectories soon after glucocorticoid initiation are relevant for the design and analysis of clinical trials of novel drugs. We describe early COA trajectories, associated factors, and the time from glucocorticoid initiation to COA peak.

METHODS

This was a prospective 18-month analysis of the Finding the Optimum Corticosteroid Regimen for Duchenne Muscular Dystrophy study. Four COAs were investigated: rise from supine velocity (RFV), 10-meter walk/run velocity (10MWRV), North Star Ambulatory Assessment (NSAA) total score, and 6-minute walk test distance (6MWT). The relationships of baseline age (4-5 vs 6-7 years), COA baseline performance, genotype, and glucocorticoid regimen (daily vs intermittent) with the COA trajectories were evaluated using linear mixed-effects models.

RESULTS

One hundred ninety-six glucocorticoid-naïve boys with DMD aged 4-7 years were enrolled. The mean age at baseline was 5.9 ± 1.0 years, 66% (n = 130) were on daily regimens, 55% (n = 107) showed a 6MWT distance >330 metres; 41% (n = 78) showed RFV >0.2 rise/s; 76% (n = 149) showed 10MWRV >0.142 10m/s, and 41.0% (n = 79) showed NSAA total score >22 points. Mean COA trajectories differed by age at glucocorticoid initiation (p < 0.01 for RFV, 10MWRV, and NSAA; p < 0.05 for 6MWT) and regimen (p < 0.01 for RFV, 10MWRV, and NSAA). Boys younger than 6 years reached their peak performance 12-18 months after glucocorticoid initiation. Boys aged 6 years or older on a daily regimen peaked between months 9 and 12 and those on an intermittent regimen by 9 months. The baseline COA performance was associated with the NSAA (p < 0.01) and the 6MWT trajectory in boys younger than 6 years on a daily regimen (p < 0.01). Differences in the mean trajectories by genotype were not significant.

DISCUSSION

Glucocorticoid regimen, age, duration of glucocorticoid exposure, and baseline COA performance need to be considered in the design and analysis of clinical trials in young boys with DMD.

Safety and efficacy of givinostat in boys with Duchenne muscular dystrophy (EPIDYS): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Duchenne muscular dystrophy, the most common childhood muscular dystrophy, is caused by dystrophin deficiency. Preclinical and phase 2 study data have suggested that givinostat, a histone deacetylase inhibitor, might help to counteract the effects of this deficiency. We aimed to evaluate the safety and efficacy of givinostat in the treatment of Duchenne muscular dystrophy.

METHODS

This multicentre, randomised, double-blind, placebo-controlled, phase 3 trial was done at 41 tertiary care sites in 11 countries. Eligible participants were ambulant, male, and aged at least 6 years, had a genetically confirmed diagnosis of Duchenne muscular dystrophy, completed two four-stair climb assessments with a mean of 8 s or less (≤1 s variance), had a time-to-rise of at least 3 s but less than 10 s, and had received systemic corticosteroids for at least 6 months. Participating boys were randomly assigned (2:1, allocated according to a list generated by the interactive response technology provider) to receive either oral givinostat or matching placebo twice a day for 72 weeks, stratified by concomitant steroid use. Boys, investigators, and site and sponsor staff were masked to treatment assignment. The dose was flexible, based on weight, and was reduced if not tolerated. Boys were divided into two groups on the basis of their baseline vastus lateralis fat fraction (VLFF; measured by magnetic resonance spectroscopy): group A comprised boys with a VLFF of more than 5% but no more than 30%, whereas group B comprised boys with a VLFF of 5% or less, or more than 30%. The primary endpoint compared the effects of givinostat and placebo on the change in results of the four-stair climb assessment between baseline and 72 weeks, in the intention-to-treat, group A population. Safety was assessed in all randomly assigned boys who received at least one dose of study drug. When the first 50 boys in group A completed 12 months of treatment, an interim futility assessment was conducted, after which the sample size was adapted using masked data from the four-stair climb assessments. Furthermore, the starting dose of givinostat was reduced following a protocol amendment. This trial is registered with ClinicalTrials.gov, NCT02851797, and is complete.

FINDINGS

Between June 6, 2017, and Feb 22, 2022, 359 boys were assessed for eligibility. Of these, 179 were enrolled into the study (median age 9·8 years [IQR 8·1-11·0]), all of whom were randomly assigned (118 to receive givinostat and 61 to receive placebo); 170 (95%) boys completed the study. Of the 179 boys enrolled, 120 (67%) were in group A (81 givinostat and 39 placebo); of these, 114 (95%) completed the study. For participants in group A, comparing the results of the four-stair climb assessment at 72 weeks and baseline, the geometric least squares mean ratio was 1·27 (95% CI 1·17-1·37) for boys receiving givinostat and 1·48 (1·32-1·66) for those receiving placebo (ratio 0·86, 95% CI 0·745-0·989; p=0·035). The most common adverse events in the givinostat group were diarrhoea (43 [36%] of 118 boys vs 11 [18%] of 61 receiving placebo) and vomiting (34 [29%] vs 8 [13%]); no treatment-related deaths occurred.

INTERPRETATION

Among ambulant boys with Duchenne muscular dystrophy, results of the four-stair climb assessment worsened in both groups over the study period; however, the decline was significantly smaller with givinostat than with placebo. The dose of givinostat was reduced after an interim safety analysis, but no new safety signals were reported. An ongoing extension study is evaluating the long-term safety and efficacy of givinostat in patients with Duchenne muscular dystrophy.

FUNDING

Italfarmaco.

Practical Considerations for Delandistrogene Moxeparvovec Gene Therapy in Patients With Duchenne Muscular Dystrophy

BACKGROUND

Delandistrogene moxeparvovec is a gene transfer therapy approved in the United States, United Arab Emirates, and Qatar for the treatment of ambulatory patients aged four through five years with a confirmed Duchenne muscular dystrophy (DMD)-causing mutation in the DMD gene. This therapy was developed to address the underlying cause of DMD through targeted skeletal, respiratory, and cardiac muscle expression of delandistrogene moxeparvovec micro-dystrophin, an engineered, functional dystrophin protein.

METHODS

Drawing on clinical trial experience from Study 101 (NCT03375164), Study 102 (NCT03769116), and ENDEAVOR (Study 103; NCT04626674), we outline practical considerations for delandistrogene moxeparvovec treatment.

RESULTS

Before infusion, the following are recommended: (1) screen for anti-adeno-associated virus rhesus isolate serotype 74 total binding antibody titers <1:400; (2) assess liver function, platelet count, and troponin-I; (3) ensure patients are up to date with vaccinations and avoid vaccine coadministration with infusion; (4) administer additional corticosteroids starting one day preinfusion (for patients already on corticosteroids); and (5) postpone dosing patients with any infection or acute liver disease until event resolution. Postinfusion, the following are recommended: (1) monitor liver function weekly (three months postinfusion) and, if indicated, continue until results are unremarkable; (2) monitor troponin-I levels weekly (first month postinfusion, continuing if indicated); (3) obtain platelet counts weekly (two weeks postinfusion), continuing if indicated; and (4) maintain the corticosteroid regimen for at least 60 days postinfusion, unless earlier tapering is indicated.

CONCLUSIONS

Although the clinical safety profile of delandistrogene moxeparvovec has been consistent, monitorable, and manageable, these practical considerations may mitigate potential risks in a real-world clinical practice setting.

Efficacy and Safety of Vamorolone Over 48 Weeks in Boys With Duchenne Muscular Dystrophy: A Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

Vamorolone is a dissociative agonist of the glucocorticoid receptor that has shown similar efficacy and reduced safety concerns in comparison with prednisone in Duchenne muscular dystrophy (DMD). This study was conducted to determine the efficacy and safety of vamorolone over 48 weeks and to study crossover participants (prednisone to vamorolone; placebo to vamorolone).

METHODS

A randomized, double-blind, placebo-controlled and prednisone-controlled clinical trial of 2 doses of vamorolone was conducted in participants with DMD, in the ages from 4 years to younger than 7 years at baseline. The interventions were 2 mg/kg/d of vamorolone and 6 mg/kg/d of vamorolone for 48 weeks (period 1: 24 weeks + period 2: 24 weeks) and 0.75 mg/kg/d of prednisone and placebo for the first 24 weeks (before crossover). Efficacy was evaluated through gross motor outcomes and safety through adverse events, growth velocity, body mass index (BMI), and bone turnover biomarkers. This analysis focused on period 2.

RESULTS

A total of 121 participants with DMD were randomized. Vamorolone at a dose of 6 mg/kg/d showed maintenance of improvement for all motor outcomes to week 48 (e.g., for primary outcome, time to stand from supine [TTSTAND] velocity, week 24 least squares mean [LSM] [SE] 0.052 [0.0130] rises/s vs week 48 LSM [SE] 0.0446 [0.0138]). After 48 weeks, vamorolone at a dose of 2 mg/kg/d showed similar improvements as 6 mg/kg/d for North Star Ambulatory Assessment (NSAA) (vamorolone 6 mg/kg/d-vamorolone 2 mg/kg/d LSM [SE] 0.49 [1.14]; 95% CI -1.80 to 2.78, p = 0.67), but less improvement for other motor outcomes. The placebo to vamorolone 6 mg/kg/d group showed rapid improvements after 20 weeks of treatment approaching benefit seen with 48-week 6 mg/kg/d of vamorolone treatment for TTSTAND, time to run/walk 10 m, and NSAA. There was significant improvement in linear growth after crossover in the prednisone to vamorolone 6 mg/kg/d group, and rapid reversal of prednisone-induced decline in bone turnover biomarkers in both crossover groups. There was an increase in BMI after 24 weeks of treatment that then stabilized for both vamorolone groups.

DISCUSSION

Improvements of motor outcomes seen with 6 mg/kg/d of vamorolone at 24 weeks of treatment were maintained to 48 weeks of treatment. Vamorolone at a dose of 6 mg/kg/d showed better maintenance of effect compared with vamorolone at a dose of 2 mg/kg/d for most (3/5) motor outcomes. Bone morbidities of prednisone (stunting of growth and declines in serum bone biomarkers) were reversed when treatment transitioned to vamorolone.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifier: NCT03439670.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that for boys with DMD, the efficacy of vamorolone at a dose of 6 mg/kg/d was maintained over 48 weeks.

Gait Event Detection and Travel Distance Using Waist-Worn Accelerometers across a Range of Speeds: Automated Approach

Estimation of temporospatial clinical features of gait (CFs), such as step count and length, step duration, step frequency, gait speed, and distance traveled, is an important component of community-based mobility evaluation using wearable accelerometers. However, accurate unsupervised computerized measurement of CFs of individuals with Duchenne muscular dystrophy (DMD) who have progressive loss of ambulatory mobility is difficult due to differences in patterns and magnitudes of acceleration across their range of attainable gait velocities. This paper proposes a novel calibration method. It aims to detect steps, estimate stride lengths, and determine travel distance. The approach involves a combination of clinical observation, machine-learning-based step detection, and regression-based stride length prediction. The method demonstrates high accuracy in children with DMD and typically developing controls (TDs) regardless of the participant's level of ability. Fifteen children with DMD and fifteen TDs underwent supervised clinical testing across a range of gait speeds using 10 m or 25 m run/walk (10 MRW, 25 MRW), 100 m run/walk (100 MRW), 6-min walk (6 MWT), and free-walk (FW) evaluations while wearing a mobile-phone-based accelerometer at the waist near the body's center of mass. Following calibration by a trained clinical evaluator, CFs were extracted from the accelerometer data using a multi-step machine-learning-based process and the results were compared to ground-truth observation data. Model predictions vs. observed values for step counts, distance traveled, and step length showed a strong correlation (Pearson's r = -0.9929 to 0.9986, p < 0.0001). The estimates demonstrated a mean (SD) percentage error of 1.49% (7.04%) for step counts, 1.18% (9.91%) for distance traveled, and 0.37% (7.52%) for step length compared to ground-truth observations for the combined 6 MWT, 100 MRW, and FW tasks. Our study findings indicate that a single waist-worn accelerometer calibrated to an individual's stride characteristics using our methods accurately measures CFs and estimates travel distances across a common range of gait speeds in both DMD and TD peers.

Gait Characterization in Duchenne Muscular Dystrophy (DMD) Using a Single-Sensor Accelerometer: Classical Machine Learning and Deep Learning Approaches

Differences in gait patterns of children with Duchenne muscular dystrophy (DMD) and typically developing (TD) peers are visible to the eye, but quantifications of those differences outside of the gait laboratory have been elusive. In this work, we measured vertical, mediolateral, and anteroposterior acceleration using a waist-worn iPhone accelerometer during ambulation across a typical range of velocities. Fifteen TD and fifteen DMD children from 3 to 16 years of age underwent eight walking/running activities, including five 25 m walk/run speed-calibration tests at a slow walk to running speeds (SC-L1 to SC-L5), a 6-min walk test (6MWT), a 100 m fast walk/jog/run (100MRW), and a free walk (FW). For clinical anchoring purposes, participants completed a Northstar Ambulatory Assessment (NSAA). We extracted temporospatial gait clinical features (CFs) and applied multiple machine learning (ML) approaches to differentiate between DMD and TD children using extracted temporospatial gait CFs and raw data. Extracted temporospatial gait CFs showed reduced step length and a greater mediolateral component of total power (TP) consistent with shorter strides and Trendelenberg-like gait commonly observed in DMD. ML approaches using temporospatial gait CFs and raw data varied in effectiveness at differentiating between DMD and TD controls at different speeds, with an accuracy of up to 100%. We demonstrate that by using ML with accelerometer data from a consumer-grade smartphone, we can capture DMD-associated gait characteristics in toddlers to teens.

Findings from the Longitudinal CINRG Becker Natural History Study

BACKGROUND

Becker muscular dystrophy is an X-linked, genetic disorder causing progressive degeneration of skeletal and cardiac muscle, with a widely variable phenotype.

OBJECTIVE

A 3-year, longitudinal, prospective dataset contributed by patients with confirmed Becker muscular dystrophy was analyzed to characterize the natural history of this disorder. A better understanding of the natural history is crucial to rigorous therapeutic trials.

METHODS

A cohort of 83 patients with Becker muscular dystrophy (5-75 years at baseline) were followed for up to 3 years with annual assessments. Muscle and pulmonary function outcomes were analyzed herein. Age-stratified statistical analysis and modeling were conducted to analyze cross-sectional data, time-to-event data, and longitudinal data to characterize these clinical outcomes.

RESULTS

Deletion mutations of dystrophin exons 45-47 or 45-48 were most common. Subgroup analysis showed greater pairwise association between motor outcomes at baseline than association between these outcomes and age. Stronger correlations between outcomes for adults than for those under 18 years were also observed. Using cross-sectional binning analysis, a ceiling effect was seen for North Star Ambulatory Assessment but not for other functional outcomes. Longitudinal analysis showed a decline in percentage predicted forced vital capacity over the life span. There was relative stability or improved median function for motor functional outcomes through childhood and adolescence and decreasing function with age thereafter.

CONCLUSIONS

There is variable progression of outcomes resulting in significant heterogeneity of the clinical phenotype of Becker muscular dystrophy. Disease progression is largely manifest in adulthood. There are implications for clinical trial design revealed by this longitudinal analysis of a Becker natural history dataset.

The IAAM LTBP4 Haplotype is Protective Against Dystrophin-Deficient Cardiomyopathy

Background

Dilated cardiomyopathy (DCM) is a major complication of, and leading cause of mortality in Duchenne muscular dystrophy (DMD). Its severity, age at onset, and rate of progression display wide variability, whose molecular bases have been scarcely elucidated. Potential DCM-modifying factors include glucocorticoid (GC) and cardiological treatments, DMD mutation type and location, and variants in other genes.

Methods and Results

We retrospectively collected 3138 echocardiographic measurements of left ventricular ejection fraction (EF), shortening fraction (SF), and end-diastolic volume (EDV) from 819 DMD participants, 541 from an Italian multicentric cohort and 278 from the Cooperative International Neuromuscular Group Duchenne Natural History Study (CINRG-DNHS). Using generalized estimating equation (GEE) models, we estimated the yearly rate of decrease of EF (-0.80%) and SF (-0.41%), while EDV increase was not significantly associated with age. Utilizing a multivariate generalized estimating equation (GEE) model we observed that mutations preserving the expression of the C-terminal Dp71 isoform of dystrophin were correlated with decreased EDV (-11.01 mL/m2, p = 0.03) while for dp116 were correlated with decreased EF (-4.14%, p = <0.001). The rs10880 genotype in the LTBP4 gene, previously shown to prolong ambulation, was also associated with increased EF and decreased EDV (+3.29%, p = 0.002, and -10.62 mL/m2, p = 0.008) with a recessive model.

Conclusions

We quantitatively describe the progression of systolic dysfunction progression in DMD, confirm the effect of distal dystrophin isoform expression on the dystrophin-deficient heart, and identify a strong effect of LTBP4 genotype of DCM in DMD.

Delandistrogene Moxeparvovec Gene Therapy in Ambulatory Patients (Aged ≥4 to <8 Years) with Duchenne Muscular Dystrophy: 1-Year Interim Results from Study SRP-9001-103 (ENDEAVOR)

OBJECTIVE

Delandistrogene moxeparvovec is approved in the USA for the treatment of ambulatory patients (4-5 years) with Duchenne muscular dystrophy. ENDEAVOR (SRP-9001-103; NCT04626674) is a single-arm, open-label study to evaluate delandistrogene moxeparvovec micro-dystrophin expression, safety, and functional outcomes following administration of commercial process delandistrogene moxeparvovec.

METHODS

In cohort 1 of ENDEAVOR (N = 20), eligible ambulatory males, aged ≥4 to <8 years, received a single intravenous infusion of delandistrogene moxeparvovec (1.33 × 1014  vg/kg). The primary endpoint was change from baseline (CFBL) to week 12 in delandistrogene moxeparvovec micro-dystrophin by western blot. Additional endpoints evaluated included: safety; vector genome copies; CFBL to week 12 in muscle fiber-localized micro-dystrophin by immunofluorescence; and functional assessments, including North Star Ambulatory Assessment, with comparison with a propensity score-weighted external natural history control.

RESULTS

The 1-year safety profile of commercial process delandistrogene moxeparvovec in ENDEAVOR was consistent with safety data reported in other delandistrogene moxeparvovec trials (NCT03375164 and NCT03769116). Delandistrogene moxeparvovec micro-dystrophin expression was robust, with sarcolemmal localization at week 12; mean (SD) CFBL in western blot, 54.2% (42.6); p < 0.0001. At 1 year, patients demonstrated stabilized or improved North Star Ambulatory Assessment total scores; mean (SD) CFBL, +4.0 (3.5). Treatment versus a propensity score-weighted external natural history control demonstrated a statistically significant difference in least squares mean (standard error) CFBL in North Star Ambulatory Assessment, +3.2 (0.6) points; p < 0.0001.

INTERPRETATION

Results confirm efficient transduction of muscle by delandistrogene moxeparvovec. One-year post-treatment, delandistrogene moxeparvovec was well tolerated, and demonstrated stabilized or improved motor function, suggesting a clinical benefit for patients with Duchenne muscular dystrophy. ANN NEUROL 2023;94:955-968.

Sleep Disordered Breathing in Children with Neuromuscular Disease

Sleep disordered breathing (SDB) in children with neuromuscular disease (NMD) is more prevalent compared to the general population, and often manifests as sleep-related hypoventilation, sleep-related hypoxemia, obstructive sleep apnea, central sleep apnea, and/or disordered control of breathing. Other sleep problems include, sleep fragmentation, abnormal sleep architecture, and nocturnal seizures in certain neuromuscular diseases. The manifestation of sleep disordered breathing in children depends on the extent, type, and progression of neuromuscular weakness, and in some instances, may be the first sign of a neuromuscular weakness leading to diagnosis of an NMD. In-lab diagnostic polysomnography (PSG) remains the gold standard for the diagnosis of sleep disordered breathing in children, but poses several challenges, including access to many children with neuromuscular disease who are non-ambulatory. If SDB is untreated, it can result in significant morbidity and mortality. Hence, we aimed to perform a comprehensive review of the literature of SDB in children with NMD. This review includes pathophysiological changes during sleep, clinical evaluation, diagnosis, challenges in interpreting PSG data using American Academy of Sleep (AASM) diagnostic criteria, management of SDB, and suggests areas for future research.

Expression of SRP-9001 dystrophin and stabilization of motor function up to 2 years post-treatment with delandistrogene moxeparvovec gene therapy in individuals with Duchenne muscular dystrophy

Introduction: Delandistrogene moxeparvovec (SRP-9001) is an investigational gene transfer therapy designed for targeted expression of SRP-9001 dystrophin protein, a shortened dystrophin retaining key functional domains of the wild-type protein. Methods: This Phase 2, double-blind, two-part (48 weeks per part) crossover study (SRP-9001-102 [Study 102]; NCT03769116) evaluated delandistrogene moxeparvovec in patients, aged ≥4 to <8 years with Duchenne muscular dystrophy. Primary endpoints (Part 1) were change from baseline (CFBL) in SRP-9001 dystrophin expression (Week 12), by Western blot, and in North Star Ambulatory Assessment (NSAA) score (Week 48). Safety assessments included treatment-related adverse events (TRAEs). Patients were randomized and stratified by age to placebo (n = 21) or delandistrogene moxeparvovec (n = 20) and crossed over for Part 2. Results: SRP-9001 dystrophin expression was achieved in all patients: mean CFBL to Week 12 was 23.82% and 39.64% normal in Parts 1 and 2, respectively. In Part 1, CFBL to Week 48 in NSAA score (least-squares mean, LSM [standard error]) was +1.7 (0.6) with treatment versus +0.9 (0.6) for placebo; p = 0.37. Disparity in baseline motor function between groups likely confounded these results. In 4- to 5-year-olds with matched baseline motor function, CFBL to Week 48 in NSAA scores was significantly different (+2.5 points; p = 0.0172), but not significantly different in 6-to-7-year-olds with imbalanced baseline motor function (-0.7 points; p = 0.5384). For patients treated with delandistrogene moxeparvovec in Part 2, CFBL to Week 48 in NSAA score was +1.3 (2.7), whereas for those treated in Part 1, NSAA scores were maintained. As all patients in Part 2 were exposed to treatment, results were compared with a propensity-score-weighted external control (EC) cohort. The LSM difference in NSAA score between the Part 2 treated group and EC cohort was statistically significant (+2.0 points; p = 0.0009). The most common TRAEs were vomiting, decreased appetite, and nausea. Most occurred within the first 90 days and all resolved. Discussion: Results indicate robust expression of SRP-9001 dystrophin and overall stabilization in NSAA up to 2 years post-treatment. Differences in NSAA between groups in Part 1 were not significant for the overall population, likely because cohorts were stratified only by age, and other critical prognostic factors were not well matched at baseline.

Assessing the value of delandistrogene moxeparvovec (SRP-9001) gene therapy in patients with Duchenne muscular dystrophy in the United States

Background: Delandistrogene moxeparvovec (SRP-9001) is an investigational gene therapy that may delay progression of Duchenne muscular dystrophy (DMD), a severe, rare neuromuscular disease caused by DMD gene mutations. Early cost-effectiveness analyses are important to help contextualize the value of gene therapies for reimbursement decision making. Objective: To determine the potential value of delandistrogene moxeparvovec using a cost-effectiveness analysis. Study design: A simulation calculated lifetime costs and equal value of life years gained (evLYG). Inputs included extrapolated clinical trial results and published utilities/costs. As a market price for delandistrogene moxeparvovec has not been established, threshold analyses established maximum treatment costs as they align with value, including varying willingness-to-pay up to $500,000, accounting for severity/rarity. Setting: USA, healthcare system perspective Patients: Boys with DMD Intervention: Delandistrogene moxeparvovec plus standard of care (SoC; corticosteroids) versus SoC alone Main outcome measure: Maximum treatment costs at a given willingness-to-pay threshold Results: Delandistrogene moxeparvovec added 10.30 discounted (26.40 undiscounted) evLYs. The maximum treatment cost was approximately $5 M, assuming $500,000/evLYG. Varying the benefit discount rate to account for the single administration increased the estimated value to #$5M, assuming $500,000/evLYG. Conclusion: In this early economic model, delandistrogene moxeparvovec increases evLYs versus SoC and begins to inform its potential value from a healthcare perspective.

Safety and effectiveness of ataluren in patients with nonsense mutation DMD in the STRIDE Registry compared with the CINRG Duchenne Natural History Study (2015-2022): 2022 interim analysis

OBJECTIVE

Strategic Targeting of Registries and International Database of Excellence (STRIDE) is an ongoing, international, multicenter registry of real-world ataluren use in individuals with nonsense mutation Duchenne muscular dystrophy (nmDMD) in clinical practice. This updated interim report (data cut-off: January 31, 2022), describes STRIDE patient characteristics and ataluren safety data, as well as the effectiveness of ataluren plus standard of care (SoC) in STRIDE versus SoC alone in the Cooperative International Neuromuscular Research Group (CINRG) Duchenne Natural History Study (DNHS).

METHODS

Patients are followed up from enrollment for at least 5 years or until study withdrawal. Propensity score matching was performed to identify STRIDE and CINRG DNHS patients who were comparable in established predictors of disease progression.

RESULTS

As of January 31, 2022, 307 patients were enrolled from 14 countries. Mean (standard deviation [SD]) ages at first symptoms and at genetic diagnosis were 2.9 (1.7) years and 4.5 (3.7) years, respectively. Mean (SD) duration of ataluren exposure was 1671 (56.8) days. Ataluren had a favorable safety profile; most treatment-emergent adverse events were mild or moderate and unrelated to ataluren. Kaplan-Meier analyses demonstrated that ataluren plus SoC significantly delayed age at loss of ambulation by 4 years (p < 0.0001) and age at decline to %-predicted forced vital capacity of < 60% and < 50% by 1.8 years (p = 0.0021) and 2.3 years (p = 0.0207), respectively, compared with SoC alone.

CONCLUSION

Long-term, real-world treatment with ataluren plus SoC delays several disease progression milestones in individuals with nmDMD. NCT02369731; registration date: February 24, 2015.

Disease progression rates in ambulatory Duchenne muscular dystrophy by steroid type, patient age and functional status

Aim: To examine benefits of corticosteroids for Duchenne muscular dystrophy (DMD) by age and disease progression. Methods: Data from daily steroid users (placebo-treated) were pooled from four phase 2b/3 trials in DMD. Outcomes assessed overall and among subgroups included changes from baseline to 48 weeks in six-minute walk distance (6MWD), timed function tests and North Star Ambulatory Assessment total score. Results: Among 231 patients receiving deflazacort (n = 127) or prednisone (n = 104), observed differences in 6MWD favoring deflazacort over prednisone were significant for patients with relatively older age (≥8-years-old), greater disease progression (baseline timed stand from supine ≥5 s), or longer corticosteroid use (>3 years). Conclusion: Daily deflazacort had greater benefits than daily prednisone particularly among older/more progressed patients.

Efficacy and Safety of Viltolarsen in Boys With Duchenne Muscular Dystrophy: Results From the Phase 2, Open-Label, 4-Year Extension Study

Background: Duchenne muscular dystrophy (DMD) is caused by DMD gene mutations, resulting in absence of functional dystrophin protein. Viltolarsen, an exon 53 skipping therapy, significantly increased dystrophin levels in patients with DMD. Presented here are completed study results of >4 years of functional outcomes in viltolarsen-treated patients compared to a historical control group (Cooperative International Neuromuscular Research Group Duchenne Natural History Study [CINRG DNHS]). Objective: To evaluate the efficacy and safety of viltolarsen for an additional 192 weeks in boys with DMD. Methods: This phase 2, open-label, 192-week long-term extension (LTE) study (NCT03167255) evaluated the efficacy and safety of viltolarsen in participants aged 4 to <10 years at baseline with DMD amenable to exon 53 skipping. All 16 participants from the initial 24-week study enrolled into this LTE. Timed function tests were compared to the CINRG DNHS group. All participants received glucocorticoid treatment. The primary efficacy outcome was time to stand from supine (TTSTAND). Secondary efficacy outcomes included additional timed function tests. Safety was continuously assessed. Results: For the primary efficacy outcome (TTSTAND), viltolarsen-treated patients showed stabilization of motor function over the first two years and significant slowing of disease progression over the following two years compared with the CINRG DNHS control group which declined. Viltolarsen was well tolerated, with most reported treatment-emergent adverse events being mild or moderate. No participants discontinued drug during the study. Conclusions: Based on the results of this 4-year LTE, viltolarsen can be an important treatment strategy for DMD patients amenable to exon 53 skipping.

Modeling Early Heterogeneous Rates of Progression in Boys with Duchenne Muscular Dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) exhibits substantial variability in rates of disease progression and response to treatment. This has hindered treatment development and complicated interpretation of drug effects in clinical trials.

OBJECTIVE

We hypothesized that a multivariate combination of early-age clinical outcome measurements can explain differential disease progression.

METHODS

Data on boys with DMD (ages 4-<10 years), both treated with steroidal anti-inflammatories and untreated, were obtained from CINRG Duchenne Natural History Study (n = 209) and vamorolone VBP15-002/003/LTE (n = 46) studies. Velocities from three timed function tests (TFTs; stand from supine, run/walk 10 meters, and climb 4 stairs) were simultaneously modeled in a longitudinal latent class analysis.

RESULTS

Three classes of differentially progressing early age DMD motor trajectories were identified. Quicker decline/progression was associated with lower baseline TFT velocities, earlier loss of ability to finish a TFT, and lower predicted velocities. Earlier substantial steroid exposure was associated with greater TFT velocities while the moderate progression class was observed to have the largest difference in performance between boys treated early with steroids vs. not. Sample size calculations with the class showing the largest treatment response showed a large reduction in required sample size as compared to using summaries from all participants. Gene mutations were also investigated in post-hoc analyses, with mutations near the beginning of the DMD gene (Dp427 absent and Dp140/Dp71 present) found to be enriched in the slowest progressing class.

CONCLUSIONS

This study provides insight into the variation in DMD progression through a latent class analysis. Our findings show class-related trajectories of motor outcomes and pharmacological response to corticosteroids, and suggest that enrichment strategies and/or subgroup analyses could be considered further in design of therapeutic interventions in DMD.

Functional and Clinical Outcomes Associated with Steroid Treatment among Non-ambulatory Patients with Duchenne Muscular Dystrophy1

BACKGROUND

Evidence on the long-term efficacy of steroids in Duchenne muscular dystrophy (DMD) after loss of ambulation is limited.

OBJECTIVE

Characterize and compare disease progression by steroid treatment (prednisone, deflazacort, or no steroids) among non-ambulatory boys with DMD.

METHODS

Disease progression was measured by functional status (Performance of Upper Limb Module for DMD 1.2 [PUL] and Egen Klassifikation Scale Version 2 [EK] scale) and by cardiac and pulmonary function (left ventricular ejection fraction [LVEF], forced vital capacity [FVC] % -predicted, cough peak flow [CPF]). Longitudinal changes in outcomes, progression to key disease milestones, and dosing and body composition metrics were analyzed descriptively and in multivariate models.

RESULTS

This longitudinal cohort study included 86 non-ambulatory patients with DMD (mean age 13.4 years; n = 40 [deflazacort], n = 29 [prednisone], n = 17 [no steroids]). Deflazacort use resulted in slower average declines in FVC % -predicted vs. no steroids (+3.73 percentage points/year, p < 0.05). Both steroids were associated with significantly slower average declines in LVEF, improvement in CPF, and slower declines in total PUL score and EK total score vs. no steroids; deflazacort was associated with slower declines in total PUL score vs. prednisone (all p < 0.05). Both steroids also preserved functional abilities considered especially important to quality of life, including the abilities to perform hand-to-mouth function and to turn in bed at night unaided (all p < 0.05 vs. no steroids).

CONCLUSIONS

Steroid use after loss of ambulation in DMD was associated with delayed progression of important pulmonary, cardiac, and upper extremity functional deficits, suggesting some benefits of deflazacort over prednisone.

Influence of β1 Adrenergic Receptor Genotype on Longitudinal Measures of Left Ventricular Ejection Fraction and Responsiveness to ß-Blocker Therapy in Patients With Duchenne Muscular Dystrophy

The purpose of this study was to determine whether the longitudinal progression of decline in left ventricular ejection fraction (LVEF) in Duchenne muscular dystrophy (DMD) patients is moderated by ADRB1 genotype and whether the efficacy of ß-blocker therapy is influenced by genotype status. About 147 DMD patients (6-34 years.) were analyzed with a focus on β₁ adrenergic receptor (ADRB1) genotype variants. Patients were grouped by ADRB1 genotype resulting in Gly389 patients and Arg389 patients. A generalized additive mixed effects model was used to examine differences in the nonlinear trend of LVEF across patient ages between genotype groups and for ß-blocker use. Both genotype groups displayed a progressive decline in LVEF starting around the mean age of ambulation loss (~12 years). However, there was no difference between genotype groups in the progression of decline in LVEF. There was a significant effect of ß-blocker use on longitudinal LVEF, wherein patients on ß-blockers had systematically lower LVEF when compared to patients not on ß-blockers. However, the effect of ß-blocker therapy on LVEF was not affected by ADRB1 genotype. The current study did not demonstrate an influence of patient ADRB1 genotype on longitudinal LVEF in our cohort. Despite previous literature suggesting a positive influence of ß-blocker use on cardiac function in DMD patients and of an ADRB1 genotypic difference in responsiveness to ß-blocker use, we did not observe this in our cohort. Interestingly, our cohort did not demonstrate a positive influence of ß-blocker use on LVEF measures.

Efficacy and Safety of Vamorolone vs Placebo and Prednisone Among Boys With Duchenne Muscular Dystrophy: A Randomized Clinical Trial

Question

For steroidal anti-inflammatory drugs, can efficacy be retained while safety concerns are reduced among boys with Duchenne muscular dystrophy (DMD) with the novel partial receptor agonist vamorolone?

Findings

A randomized, double-blind, placebo- and prednisone-controlled trial of vamorolone (2 dose groups) was carried out in 121 patients with DMD. The trial met the primary (time to stand velocity after 24 weeks for vamorolone, 6 mg/kg per day vs placebo) and first 4 sequential secondary motor function end points; vamorolone showed loss of bone morbidities compared with prednisone, with no stunting of growth and no deleterious changes in bone biomarkers.

Meaning

This study found that vamorolone, a dissociative steroidal anti-inflammatory, was able to reduce bone morbidities while retaining efficacy.

Importance

Corticosteroidal anti-inflammatory drugs are widely prescribed but long-term use shows adverse effects that detract from patient quality of life.

Objective

To determine if vamorolone, a structurally unique dissociative steroidal anti-inflammatory drug, is able to retain efficacy while reducing safety concerns with use in Duchenne muscular dystrophy (DMD).

Design, Setting, and Participants

Randomized, double-blind, placebo- and prednisone-controlled 24-week clinical trial, conducted from June 29, 2018, to February 24, 2021, with 24 weeks of follow-up. This was a multicenter study (33 referral centers in 11 countries) and included boys 4 to younger than 7 years of age with genetically confirmed DMD not previously treated with corticosteroids.

Interventions

The study included 4 groups: placebo; prednisone, 0.75 mg/kg per day; vamorolone, 2 mg/kg per day; and vamorolone, 6 mg/kg per day.

Main Outcomes and Measures

Study outcomes monitored (1) efficacy, which included motor outcomes (primary: time to stand from supine velocity in the vamorolone, 6 mg/kg per day, group vs placebo; secondary: time to stand from supine velocity [vamorolone, 2 mg/kg per day], 6-minute walk distance, time to run/walk 10 m [vamorolone, 2 and 6 mg/kg per day]; exploratory: NorthStar Ambulatory Assessment, time to climb 4 stairs) and (2) safety, which included growth, bone biomarkers, and a corticotropin (ACTH)–challenge test.

Results

Among the 133 boys with DMD enrolled in the study (mean [SD] age, 5.4 [0.9] years), 121 were randomly assigned to treatment groups, and 114 completed the 24-week treatment period. The trial met the primary end point for change from baseline to week 24 time to stand velocity for vamorolone, 6 mg/kg per day (least-squares mean [SE] velocity, 0.05 [0.01] m/s vs placebo −0.01 [0.01] m/s; 95% CI, 0.02-0.10; P = .002) and the first 4 sequential secondary end points: time to stand velocity, vamorolone, 2 mg/kg per day, vs placebo; 6-minute walk test, vamorolone, 6 mg/kg per day, vs placebo; 6-minute walk test, vamorolone, 2 mg/kg per day, vs placebo; and time to run/walk 10 m velocity, vamorolone, 6 mg/kg per day, vs placebo. Height percentile declined in prednisone-treated (not vamorolone-treated) participants (change from baseline [SD]: prednisone, −1.88 [8.81] percentile vs vamorolone, 6 mg/kg per day, +3.86 [6.16] percentile; P = .02). Bone turnover markers declined with prednisone but not with vamorolone. Boys with DMD at baseline showed low ACTH-stimulated cortisol and high incidence of adrenal insufficiency. All 3 treatment groups led to increased adrenal insufficiency.

Conclusions and Relevance

In this pivotal randomized clinical trial, vamorolone was shown to be effective and safe in the treatment of boys with DMD over a 24-week treatment period. Vamorolone may be a safer alternative than prednisone in this disease, in which long-term corticosteroid use is the standard of care.

Trial Registration

ClinicalTrials.gov Identifier: NCT03439670

Novel approaches to analysis of the North Star Ambulatory Assessment (NSAA) in Duchenne muscular dystrophy (DMD): Observations from a phase 2 trial

Introduction

The North Star Ambulatory Assessment (NSAA) tool is a key instrument for measuring clinical outcomes in patients with Duchenne muscular dystrophy (DMD). To gain a better understanding of the longitudinal utility of the NSAA, we evaluated NSAA data from a phase II trial of 120 patients with DMD treated with domagrozumab or placebo.

Methods

The NSAA exploratory analyses included assessment of individual skills gained/lost, total skills gained/lost, cumulative loss of function, and the impact of transient loss of function due to a temporary disability on NSAA total score (temporary zero score).

Results

There was no significant difference in the total number of NSAA skills gained (mean 1.41 and 1.04, respectively; p = 0.3314) or lost (3.90 vs. 5.0; p = 0.0998) between domagrozumab- vs. placebo-treated patients at week 49. However, domagrozumab-treated patients were less likely to lose the ability to perform a NSAA item (hazard ratio 0.80, 95% confidence interval [CI]: 0.65–0.98, p = 0.029) over 48-weeks vs. placebo-treated patients. When temporary zero scores were changed to “not obtainable” (8 values from 7 patients), domagrozumab-treated patients scored higher on the NSAA total score versus placebo-treated patients (difference at week 49: 2.0, 95% CI: 0.1–3.9, p = 0.0359).

Conclusions

These exploratory analyses reveal additional approaches to interpreting the NSAA data beyond just change in NSAA total score. These observations also highlight the importance of reporting items as “not obtainable” for a patient with a temporary/transient physical disability that impacts their ability to perform the NSAA test.

ClinicalTrials.gov identifier

NCT02310763.

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

Duchenne muscular dystrophy (DMD) is a progressive, neuromuscular disorder caused by mutations in the DMD gene that results in a lack of functional dystrophin protein. Herein, we report the use of quantitative magnetic resonance imaging (MRI) measures as biomarkers in the context of a multicenter phase 2, randomized, placebo-controlled clinical trial evaluating the myostatin inhibitor domagrozumab in ambulatory boys with DMD (n = 120 aged 6 to < 16 years). MRI scans of the thigh to measure muscle volume, muscle volume index (MVI), fat fraction, and T2 relaxation time were obtained at baseline and at weeks 17, 33, 49, and 97 as per protocol. These quantitative MRI measurements appeared to be sensitive and objective biomarkers for evaluating disease progression, with significant changes observed in muscle volume, MVI, and T2 mapping measures over time. To further explore the utility of quantitative MRI measures as biomarkers to inform longer term functional changes in this cohort, a regression analysis was performed and demonstrated that muscle volume, MVI, T2 mapping measures, and fat fraction assessment were significantly correlated with longer term changes in four-stair climb times and North Star Ambulatory Assessment functional scores. Finally, less favorable baseline measures of MVI, fat fraction of the muscle bundle, and fat fraction of lean muscle were significant risk factors for loss of ambulation over a 2-year monitoring period. These analyses suggest that MRI can be a valuable tool for use in clinical trials and may help inform future functional changes in DMD.Trial registration: ClinicalTrials.gov identifier, NCT02310763; registered December 2014.

Delays in pulmonary decline in eteplirsen-treated patients with Duchenne muscular dystrophy

INTRODUCTION/AIMS

Pulmonary decline is an important issue in patients with Duchenne muscular dystrophy (DMD). Eteplirsen is a US-approved treatment for patients with DMD and exon 51 skip-amenable mutations. Previous analyses have shown that eteplirsen is associated with statistically significant attenuation of pulmonary decline. This study evaluates the effect of eteplirsen treatment from newly available data sources on pulmonary function over time in patients with DMD.

METHODS

This study uses a post hoc pooled analysis to compare the percentage of predicted forced vital capacity (FVC%p) and projected time to pulmonary function milestones in patients with DMD and exon 51 skip-amenable mutations receiving eteplirsen (Studies 204 and 301) or standard of care (SoC; Cooperative International Neuromuscular Research Group Duchenne Natural History Study). A mixed model for repeated measures framework was applied to evaluate the impact of eteplirsen.

RESULTS

An average annual rate of FVC%p decline for eteplirsen-treated patients was estimated to be 3.47%, which was a statistically significant attenuation from the 5.95% rate of decline estimated in SoC patients (P = 0.0001). Using linear extrapolations of the model-estimated decline in FVC%p, the attenuation in FVC%p decline for eteplirsen-treated patients corresponded to a delay of 5.72 years in time to needing continuous ventilation, 3.31 years in time to needing nighttime ventilation, and 2.11 years in time to needing a cough assist device compared with SoC patients.

DISCUSSION

The attenuation of FVC%p decline suggests that eteplirsen-treated patients experienced statistically significant and clinically meaningful attenuations in pulmonary decline compared with SoC patients. This article is protected by copyright. All rights reserved.

Comparing Deflazacort and Prednisone in Duchenne Muscular Dystrophy

Deflazacort and prednisone/prednisolone are the current standard of care for patients with Duchenne muscular dystrophy (DMD) based on evidence that they improve muscle strength, improve timed motor function, delay loss of ambulation, improve pulmonary function, reduce the need for scoliosis surgery, delay onset of cardiomyopathy, and increase survival. Both have been used off-label for many years (choice dependent on patient preference, cost, and geographic location) before FDA approval of deflazacort for DMD in 2017. In this review, we compare deflazacort and prednisone/prednisolone in terms of their key pharmacological features, relative efficacy, and safety profiles in patients with DMD. Differentiating features include lipid solubility, pharmacokinetics, changes in gene expression profiles, affinity for the mineralocorticoid receptor, and impact on glucose metabolism. Evidence from randomized clinical trials, prospective studies, meta-analyses, and post-hoc analyses suggests that patients receiving deflazacort experience similar or slower rates of functional decline compared with those receiving prednisone/prednisolone. Regarding side effects, weight gain and behavior side effects appear to be greater with prednisone/prednisolone than with deflazacort, whereas bone health, growth parameters, and cataracts appear worse with deflazacort.

Longitudinal changes in cardiac function in Duchenne muscular dystrophy population as measured by magnetic resonance imaging

BACKGROUND

The lack of dystrophin in cardiomyocytes in Duchenne muscular dystrophy (DMD) is associated with progressive decline in cardiac function eventually leading to death by 20-40 years of age. The aim of this prospective study was to determine rate of progressive decline in left ventricular (LV) function in Duchenne muscular dystrophy (DMD) over 5 years.

METHODS

Short axis cine and grid tagged images of the LV were acquired in individuals with DMD (n = 59; age = 5.3-18.0 years) yearly, and healthy controls at baseline (n = 16, age = 6.0-18.3 years) on a 3 T MRI scanner. Grid-tagged images were analyzed for composite circumferential strain (ℇcc%) and ℇcc% in six mid LV segments. Cine images were analyzed for left ventricular ejection fraction (LVEF), LV mass (LVM), end-diastolic volume (EDV), end-systolic volume (ESV), LV atrioventricular plane displacement (LVAPD), and circumferential uniformity ratio estimate (CURE). LVM, EDV, and ESV were normalized to body surface area for a normalized index of LVM (LVMI), EDV (EDVI) and ESV (ESVI).

RESULTS

At baseline, LV ℇcc% was significantly worse in DMD compared to controls and five of the six mid LV segments demonstrated abnormal strain in DMD. Longitudinal measurements revealed that ℇcc% consistently declined in individuals with DMD with the inferior segments being more affected. LVEF progressively declined between 3 to 5 years post baseline visit. In a multivariate analysis, the use of cardioprotective drugs trended towards positively impacting cardiac measures while loss of ambulation and baseline age were associated with negative impact. Eight out of 17 cardiac parameters reached a minimal clinically important difference with a threshold of 1/3 standard deviation.

CONCLUSION

The study shows a worsening of circumferential strain in dystrophic myocardium. The findings emphasize the significance of early and longitudinal assessment of cardiac function in DMD and identify early biomarkers of cardiac dysfunction to help design clinical trials to mitigate cardiac pathology. This study provides valuable non-invasive and non-contrast based natural history data of cardiac changes which can be used to design clinical trials or interpret the results of current trials aimed at mitigating the effects of decreased cardiac function in DMD.

074 Long-term effect of idebenone in reducing respiratory function decline in patients with Duchenne muscular dystrophy

Two placebo-controlled trials of 52-week duration showed that idebenone consistently reduced respira- tory function decline rate in patients with DMD. Long-term data from the DELPHI-Extension (DELPHI-E) study and SYROS (DELOS patients who transitioned to idebenone under an Expanded Access Program) are now presented. The aim was to assess the consistency of the long-term effect of idebenone.

11 DELPHI-E and 18 SYROS patients with abnormal (<80%) forced vital capacity (as percent predicted, FVC%p) were treated with idebenone for an average of 2.0 and 4.2 years respectively. Annualized FVC%p decline rates were compared to untreated patients from SYROS or matched external controls.

Mean (SD) baseline age was 13.6 (2.3) and 13.3 (2.7) years in DELPHI (N=11) and DELOS (N=18), respec- tively, and FVC%p was 47.2% (19.7%) and 58.7% (17.6%). For the first 2-year period, the average annual decline rate was comparable in treated patients (4.5% and 5.4% in DELPHI-E and SYROS) and lower than in untreated SYROS patients and external controls (7.9% untreated and 8.1% in CINRG-DNHS). During years 3–6, the annual decline rate was consistently lower than for matched controls.

Treatment with idebenone resulted in a sustained reduction in the rate of decline in respiratory function. laurent.servais@paediatrics.ox.ac.uk

Long-Term Functional Efficacy and Safety of Viltolarsen in Patients with Duchenne Muscular Dystrophy

Background: Duchenne muscular dystrophy (DMD) is a rare, genetic disease caused by mutations in the DMD gene resulting in an absence of functional dystrophin protein. Viltolarsen, an exon 53 skipping therapy, has been shown to increase endogenous dystrophin levels. Herein, long-term (>2 years) functional outcomes in viltolarsen treated patients were compared to a matched historical control group. Objective: To evaluate long-term efficacy and safety of the anti-sense oligonucleotide viltolarsen in the treatment of patients with DMD amenable to exon 53 skipping therapy. Methods: This trial (NCT03167255) is the extension of a previously published 24-week trial in North America (NCT02740972) that examined dystrophin levels, timed function tests compared to a matched historical control group (Cooperative International Neuromuscular Research Group Duchenne Natural History Study, CINRG DNHS), and safety in boys 4 to <  10 years (N = 16) with DMD amenable to exon 53 skipping who were treated with viltolarsen. Both groups were treated with glucocorticoids. All 16 participants elected to enroll in this long-term trial (up to 192 weeks) to continue evaluation of motor function and safety. Results: Time to stand from supine and time to run/walk 10 meters showed stabilization from baseline through week 109 for viltolarsen-treated participants whereas the historical control group showed decline (statistically significant differences for multiple timepoints). Safety was similar to that observed in the previous 24-week trial, which was predominantly mild. There have been no treatment-related serious adverse events and no discontinuations. Conclusions: Based on these results at over 2 years, viltolarsen can be a new treatment option for patients with DMD amenable to exon 53 skipping.

Repeated intravenous cardiosphere-derived cell therapy in late-stage Duchenne muscular dystrophy (HOPE-2): a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

Cardiosphere-derived cells (CDCs) ameliorate skeletal and cardiac muscle deterioration in experimental models of Duchenne muscular dystrophy. The HOPE-2 trial examined the safety and efficacy of sequential intravenous infusions of human allogeneic CDCs in late-stage Duchenne muscular dystrophy.

METHODS

In this multicentre, randomised, double-blind, placebo-controlled, phase 2 trial, patients with Duchenne muscular dystrophy, aged 10 years or older with moderate upper limb impairment, were enrolled at seven centres in the USA. Patients were randomly assigned (1:1) using stratified permuted blocks to receive CAP-1002 (1·5 × 10⁸ CDCs) or placebo intravenously every 3 months for a total of four infusions. Clinicians, caregivers, patients, and clinical operations personnel were fully masked to treatment groups. The primary outcome was the change in mid-level elbow Performance of Upper Limb version 1.2 (PUL 1.2) score at 12 months, assessed in the intention-to-treat population. Safety was assessed in all individuals who received an investigational product. This trial is registered with ClinicalTrials.gov, NCT03406780.

FINDINGS

Between March 1, 2018, and March 31, 2020, 26 male patients with Duchenne muscular dystrophy were enrolled, of whom eight were randomly assigned to the CAP-1002 group and 12 to the placebo group (six were not randomised due to screening failure). In patients who had a post-treatment PUL 1.2 assessment (eight in the CAP-1002 group and 11 in the placebo group), the mean 12-month change from baseline in mid-level elbow PUL1.2 favoured CAP-1002 over placebo (percentile difference 36·2, 95% CI 12·7-59·7; difference of 2·6 points; p=0·014). Infusion-related hypersensitivity reactions without long-term sequelae were observed in three patients, with one patient discontinuing therapy due to a severe allergic reaction. No other major adverse reactions were noted, and no deaths occurred.

INTERPRETATION

CAP-1002 cell therapy appears to be safe and effective in reducing deterioration of upper limb function in patients with late-stage Duchenne muscular dystrophy. Various measures of cardiac function and structure were also improved in the CAP-1002 group compared with the placebo group. Longer-term extension studies are needed to confirm the therapeutic durability and safety of CAP-1002 beyond 12 months for the treatment of skeletal myopathy and cardiomyopathy in Duchenne muscular dystrophy.

FUNDING

Capricor Therapeutics.

Efficacy and Safety of Vamorolone in Duchenne Muscular Dystrophy: A 30-Month Nonrandomized Controlled Open-Label Extension Trial

IMPORTANCE

Vamorolone is a synthetic steroidal drug with potent anti-inflammatory properties. Initial open-label, multiple ascending dose-finding studies of vamorolone among boys with Duchenne muscular dystrophy (DMD) found significant motor function improvement after 6 months treatment in higher-dose (ie, ≥2.0 mg/kg/d) groups.

OBJECTIVE

To investigate outcomes after 30 months of open-label vamorolone treatment.

DESIGN, SETTING, AND PARTICIPANTS

This nonrandomized controlled trial was conducted by the Cooperative International Neuromuscular Research Group at 11 US and non-US study sites. Participants were 46 boys ages 4.5 to 7.5 years with DMD who completed the 6-month dose-finding study. Data were analyzed from July 2020 through November 2021.

INTERVENTIONS

Participants were enrolled in a 24-month, long-term extension (LTE) study with vamorolone dose escalated to 2.0 or 6.0 mg/kg/d.

MAIN OUTCOMES AND MEASURES

Change in time-to-stand (TTSTAND) velocity from dose-finding baseline to end of LTE study was the primary outcome. Efficacy assessments included timed function tests, 6-minute walk test, and NorthStar Ambulatory Assessment (NSAA). Participants with DMD treated with glucocorticoids from the Duchenne Natural History Study (DNHS) and NorthStar United Kingdom (NSUK) Network were matched and compared with participants in the LTE study receiving higher doses of vamorolone.

RESULTS

Among 46 boys with DMD who completed the dose-finding study, 41 boys (mean [SD] age, 5.33 [0.96] years) completed the LTE study. Among 21 participants treated with higher-dose (ie, ≥2.0 mg/kg/d) vamorolone consistently throughout the 6-month dose-finding and 24-month LTE studies with data available at 30 months, there was a decrease in mean (SD) TTSTAND velocity from baseline to 30 months (0.206 [0.070] rises/s vs 0.189 (0.124) rises/s), which was not a statistically significant change (-0.011 rises/s; CI, -0.068 to 0.046 rises/s). There were no statistically significant differences between participants receiving higher-dose vamorolone and matched participants in the historical control groups receiving glucocorticoid treatment (75 patients in DNHS and 110 patients in NSUK) over a 2-year period in NSAA total score change (0.22 units vs NSUK; 95% CI, -4.48 to 4.04]; P = .92), body mass index z score change (0.002 vs DNHS SD/mo; 95% CI, -0.006 to 0.010; P = .58), or timed function test change. Vamorolone at doses up to 6.0 mg/kg/d was well tolerated, with 5 of 46 participants discontinuing prematurely and for reasons not associated with study drug. Participants in the DNHS treated with glucocorticoids had significant growth delay in comparison with participants treated with vamorolone who had stable height percentiles (0.37 percentile/mo; 95% CI, 0.23 to 0.52 percentile/mo) over time.

CONCLUSIONS AND RELEVANCE

This study found that vamorolone treatment was not associated with a change in TTSTAND velocity from baseline to 30 months among boys with DMD aged 4 to 7 years at enrollment. Vamorolone was associated with maintenance of muscle strength and function up to 30 months, similar to standard of care glucocorticoid therapy, and improved height velocity compared with growth deceleration associated with glucocorticoid treatment, suggesting that vamorolone may be an attractive candidate for treatment of DMD.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03038399.

A Longitudinal Study of Quantitative Muscle Strength and Functional Motor Ability in Ambulatory Boys with Duchenne Muscular Dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disorder, that is characterized by progressive muscle degeneration and loss of ambulation between 7-13 years of age. Novel pharmacological agents targeting the genetic defects and disease mechanisms are becoming available; however, corticosteroid (CS) therapy remains the standard of care.

OBJECTIVE

The purpose of this longitudinal study was to elucidate the effect of CS therapy on the rate of muscle strength and gross motor skill decline in boys with DMD and assess the sensitivity of selected outcome measures.

METHODS

Eighty-four ambulatory boys with DMD (49-180 months), 70 on CS, 14 corticosteroid naïve (NCS), participated in this 8-year multi-site study. Outcomes included; isokinetic dynamometry, the Standing (STD) and Walking/Running/jumping (WRJ) dimensions of the Gross Motor Function Measure (GMFM), and Timed Function Tests (TFTs). Nonlinear mixed modeling procedures determined the rate of change with age and the influence of steroids.

RESULTS

Despite CS therapy the rate of decline in strength with age was significant in all muscle groups assessed. CS therapy significantly slowed decline in knee extensor strength, as the NCS group declined at 3x the rate of the CS group. Concurrently, WRJ skills declined in the NCS group at twice the rate of the CS group. 4-stair climb and 10 meter walk/run performance was superior in the boys on CS therapy.

CONCLUSION

CS therapy slowed the rate of muscle strength decline and afforded longer retention of select gross motor skills in boys on CS compared to boys who were NCS. Isokinetic dynamometry, Walk/Run/Jump skills, and select TFTs may prove informative in assessing the efficacy of new therapeutics in ambulatory boys with DMD.

Ataluren delays loss of ambulation and respiratory decline in nonsense mutation Duchenne muscular dystrophy patients

Aim: We investigated the effect of ataluren plus standard of care (SoC) on age at loss of ambulation (LoA) and respiratory decline in patients with nonsense mutation Duchenne muscular dystrophy (nmDMD) versus patients with DMD on SoC alone. Patients & methods: Study 019 was a long-term Phase III study of ataluren safety in nmDMD patients with a history of ataluren exposure. Propensity score matching identified Study 019 and CINRG DNHS patients similar in disease progression predictors. Results & conclusion: Ataluren plus SoC was associated with a 2.2-year delay in age at LoA (p = 0.0006), and a 3.0-year delay in decline of predicted forced vital capacity to <60% in nonambulatory patients (p = 0.0004), versus SoC. Ataluren plus SoC delays disease progression and benefits ambulatory and nonambulatory patients with nmDMD. ClinicalTrials.gov: NCT01557400.

First Regulatory Qualification of a Novel Digital Endpoint in Duchenne Muscular Dystrophy: A Multi-Stakeholder Perspective on the Impact for Patients and for Drug Development in Neuromuscular Diseases

Background

Functional outcome measures used to assess efficacy in clinical trials of investigational treatments for rare neuromuscular diseases like Duchenne muscular dystrophy (DMD) are performance-based tasks completed by the patient during hospital visits. These are prone to bias and may not reflect motor abilities in real-world settings. Digital tools, such as wearable devices and other remote sensors, provide the opportunity for continuous, objective, and sensitive measurements of functional ability during daily life. Maintaining ambulation is of key importance to individuals with DMD. Stride velocity 95th centile (SV95C) is the first wearable acquired digital endpoint to receive qualification from the European Medicines Agency (EMA) to quantify the ambulation ability of ambulant DMD patients aged ≥5 years in drug therapeutic studies; it is also currently under review for the US Food and Drug Administration (FDA) qualification.

Summary

Focusing on SV95C as a key example, we describe perspectives of multiple stakeholders on the promise of novel digital endpoints in neuromuscular disease drug development.

Meta-analyses of deflazacort versus prednisone/prednisolone in patients with nonsense mutation Duchenne muscular dystrophy

Aim: Compare efficacies of deflazacort and prednisone/prednisolone in providing clinically meaningful delays in loss of physical milestones in patients with nonsense mutation Duchenne muscular dystrophy. Materials & methods: Placebo data from Phase IIb (ClinicalTrials.gov Identifier: NCT00592553) and ACT DMD (ClinicalTrials.gov Identifier: NCT01826487) ataluren nonsense mutation Duchenne muscular dystrophy clinical trials were retrospectively combined in meta-analyses (intent-to-treat population; for change from baseline to week 48 in 6-min walk distance [6MWD] and timed function tests). Results: Significant improvements in change in 6-min walk distance with deflazacort versus prednisone/prednisolone (least-squares mean difference 39.54 m [95% CI: 13.799, 65.286; p = 0.0026]). Significant and clinically meaningful improvements in 4-stair climb and 4-stair descend for deflazacort versus prednisone/prednisolone. Conclusion: Deflazacort provides clinically meaningful delays in loss of physical milestones over 48 weeks compared with prednisone/prednisolone for patients with nonsense mutation Duchenne muscular dystrophy.

A Combined Prospective and Retrospective Comparison of Long-Term Functional Outcomes Suggests Delayed Loss of Ambulation and Pulmonary Decline with Long-Term Eteplirsen Treatment

Background:

Studies 4658-201/202 (201/202) evaluated treatment effects of eteplirsen over 4 years in patients with Duchenne muscular dystrophy and confirmed exon-51 amenable genetic mutations. Chart review Study 4658-405 (405) further followed these patients while receiving eteplirsen during usual clinical care.

Objective:

To compare long-term clinical outcomes of eteplirsen-treated patients from Studies 201/202/405 with those of external controls.

Methods:

Median total follow-up time was approximately 6 years of eteplirsen treatment. Outcomes included loss of ambulation (LOA) and percent-predicted forced vital capacity (FVC%p). Time to LOA was compared between eteplirsen-treated patients and standard of care (SOC) external controls and was measured from eteplirsen initiation in 201/202 or, in the SOC group, from the first study visit. Comparisons were conducted using univariate Kaplan-Meier analyses and log-rank tests, and multivariate Cox proportional hazards models with regression adjustment for baseline characteristics. Annual change in FVC%p was compared between eteplirsen-treated patients and natural history study patients using linear mixed models with repeated measures.

Results:

Data were included from all 12 patients in Studies 201/202 and the 10 patients with available data from 405. Median age at LOA was 15.16 years. Eteplirsen-treated patients experienced a statistically significant longer median time to LOA by 2.09 years (5.09 vs. 3.00 years, p < 0.01) and significantly attenuated rates of pulmonary decline vs. natural history patients (FVC%p change: –3.3 vs. –6.0 percentage points annually, p < 0.0001).

Conclusions:

Study 405 highlights the functional benefits of eteplirsen on ambulatory and pulmonary function outcomes up to 7 years of follow-up in comparison to external controls.

Evaluating longitudinal therapy effects via the North Star Ambulatory Assessment

INTRODUCTION/AIMS

In comparative studies, treatment effects are typically evaluated at a specific time point. When data are collected periodically, an alternative, clinically meaningful approach could be used to assess the totality of treatment effects. We applied a well-developed analytical procedure for evaluating longitudinal treatment effects using North Star Ambulatory Assessment (NSAA) data for illustration.

METHODS

The NSAA comprises 17 scorable items/outcomes that measure changes in motor function. Using NSAA data from the published ataluren phase 3, randomized, placebo-controlled trial (NCT01826487), cumulative counts of failures to perform each item (transition from 2/1 [able/impaired] to 0 [unable]) were collected at specified time points for each patient over 48 wk. Treatment group-wise mean cumulative item failure count curves were constructed, comparing ataluren versus placebo and deflazacort versus prednisone/prednisolone among placebo-treated patients. The steeper the curve, the worse the outcome. A clinically meaningful summary of the between-group difference was provided for each comparison.

RESULTS

The curve was uniformly steeper for placebo than ataluren after 16 wk and for prednisone/prednisolone than deflazacort after 8 wk. The two curves in each comparison continued to diverge thereafter, indicating sustained treatment benefits over time. Using a unique analytical approach, cumulative failure rates were reduced, on average, by 27% for ataluren versus placebo (rate ratio, 0.73; 95% confidence interval [CI], 0.55-0.97; p = .027) and 28% for deflazacort versus prednisone/prednisolone (rate ratio, 0.72; 95% CI, 0.53-0.96; p = .028).

DISCUSSION

Unlike fixed-time analyses, this analytical approach enabled demonstration of cumulative, longitudinal treatment effects over time using repeatedly measured NSAA observations.

Comparison of Long-term Ambulatory Function in Patients with Duchenne Muscular Dystrophy Treated with Eteplirsen and Matched Natural History Controls

Background:

Duchenne muscular dystrophy (DMD) is a rare, X-linked, fatal, degenerative neuromuscular disease caused by DMD gene mutations. A relationship between exon skipping and dystrophin production in exon 51-amenable patients treated with eteplirsen (EXONDYS 51^®) is established. Once-weekly eteplirsen significantly increased dystrophin, with slower decline in ambulatory function compared to baseline. Long-term treatment with eteplirsen leads to accumulation of dystrophin over time and observed functional benefits in patients with DMD.

Objective:

Compare long-term ambulatory function in eteplirsen-treated patients versus controls.

Methods:

Study 201/202 included 12 eteplirsen-treated patients assessed twice/year for ambulatory function over 4 years. Ambulatory evaluations (6-minute walk test [6MWT], loss of ambulation, and North Star Ambulatory Assessment [NSAA]) were compared with matched controls from Italian Telethon and Leuven registries.

Results:

At Years 3 and 4, eteplirsen-treated patients demonstrated markedly greater mean 6MWT than controls (difference in change from baseline of 132 m [95%CI (29, 235), p = 0.015] at Year 3 and 159 m [95%CI (66, 253), p = 0.002] at Year 4). At Year 4, a significantly greater proportion of eteplirsen-treated patients were still ambulant versus controls (10/12 vs 3/11; p = 0.020). At Year 3, eteplirsen-treated patients demonstrated milder NSAA decline versus controls (difference in change from baseline of 2.6, 95%CI [-6, 11]), however, the difference was not statistically significant; Year 4 control NSAA data were not available.

Conclusion:

In this retrospective matched control study, eteplirsen treatment resulted in attenuation of ambulatory decline over a 4-year observation period, supporting long-term benefit in patients with DMD.

A Randomized, Double-Blind, Placebo-Controlled, Global Phase 3 Study of Edasalonexent in Pediatric Patients with Duchenne Muscular Dystrophy: Results of the PolarisDMD Trial

Background:

Edasalonexent (CAT-1004) is an orally-administered novel small molecule drug designed to inhibit NF-κB and potentially reduce inflammation and fibrosis to improve muscle function and thereby slow disease progression and muscle decline in Duchenne muscular dystrophy (DMD).

Objective:

This international, randomized 2 : 1, placebo-controlled, phase 3 study in patients ≥4 – < 8 years old with DMD due to any dystrophin mutation examined the effect of edasalonexent (100 mg/kg/day) compared to placebo over 52 weeks.

Methods:

Endpoints were changes in the North Star Ambulatory Assessment (NSAA; primary) and timed function tests (TFTs; secondary). Assessment of health-related function used the Pediatric Outcomes Data Collection tool (PODCI).

Results:

One hundred thirty one patients received edasalonexent (n = 88) and placebo (n = 43). At week 52, differences between edasalonexent and placebo for NSAA total score and TFTs were not statistically significant, although there were consistently less functional declines in the edasalonexent group. A pre-specified analysis by age demonstrated that younger patients (≤6.0 years) showed more robust and statistically significant differences between edasalonexent and placebo for some assessments. Treatment was well-tolerated and the majority of adverse events were mild, and most commonly involved the gastrointestinal system (primarily diarrhea).

Conclusions:

Edasalonexent was generally well-tolerated with a manageable safety profile at the dose of 100 mg/kg/day. Although edasalonexent did not achieve statistical significance for improvement in primary and secondary functional endpoints for assessment of DMD, subgroup analysis suggested that edasalonexent may slow disease progression if initiated before 6 years of age. (NCT03703882)

Open-Label Evaluation of Eteplirsen in Patients with Duchenne Muscular Dystrophy Amenable to Exon 51 Skipping: PROMOVI Trial

Background

Eteplirsen received accelerated FDA approval for treatment of Duchenne muscular dystrophy (DMD) with mutations amenable to exon 51 skipping, based on demonstrated dystrophin production.

Objective

To report results from PROMOVI, a phase 3, multicenter, open-label study evaluating efficacy and safety of eteplirsen in a larger cohort.

Methods

Ambulatory patients aged 7–16 years, with confirmed mutations amenable to exon 51 skipping, received eteplirsen 30 mg/kg/week intravenously for 96 weeks. An untreated cohort with DMD not amenable to exon 51 skipping was also enrolled.

Results

78/79 eteplirsen-treated patients completed 96 weeks of treatment. 15/30 untreated patients completed the study; this cohort was considered an inappropriate control group because of genotype-driven differences in clinical trajectory. At Week 96, eteplirsen-treated patients showed increased exon skipping (18.7-fold) and dystrophin protein (7-fold) versus baseline. Post-hoc comparisons with patients from eteplirsen phase 2 studies (4658-201/202) and mutation-matched external natural history controls confirmed previous results, suggesting clinically notable attenuation of decline on the 6-minute walk test over 96 weeks (PROMOVI: –68.9 m; phase 2 studies: –67.3 m; external controls: –133.8 m) and significant attenuation of percent predicted forced vital capacity annual decline (PROMOVI: –3.3%, phase 2 studies: –2.2%, external controls: –6.0%; p < 0.001). Adverse events were generally mild to moderate and unrelated to eteplirsen. Most frequent treatment-related adverse events were headache and vomiting; none led to treatment discontinuation.

Conclusions

This large, multicenter study contributes to the growing body of evidence for eteplirsen, confirming a positive treatment effect, favorable safety profile, and slowing of disease progression versus natural history.

Safety, Tolerability, and Efficacy of Viltolarsen in Boys With Duchenne Muscular Dystrophy Amenable to Exon 53 Skipping: A Phase 2 Randomized Clinical Trial

Question

What are the safety, tolerability, and efficacy of viltolarsen in boys with Duchenne muscular dystrophy (DMD) amenable to exon 53 skipping?

Findings

Results of this 4-week randomized clinical trial for safety followed by a 20-week open-label treatment period in 16 patients with DMD indicated significant drug-induced dystrophin production in both viltolarsen groups (40 mg/kg per week and 80 mg/kg week) after 20 to 24 weeks of treatment. Timed function tests provided supportive evidence of treatment-related clinical improvement, and viltolarsen was well tolerated.

Meaning

Viltolarsen may provide a new therapeutic option for patients with DMD amenable to exon 53 skipping.

Importance

An unmet need remains for safe and efficacious treatments for Duchenne muscular dystrophy (DMD). To date, there are limited agents available that address the underlying cause of the disease.

Objective

To evaluate the safety, tolerability, and efficacy of viltolarsen, a novel antisense oligonucleotide, in participants with DMD amenable to exon 53 skipping.

Design, Setting, and Participants

This phase 2 study was a 4-week randomized clinical trial for safety followed by a 20-week open-label treatment period of patients aged 4 to 9 years with DMD amenable to exon 53 skipping. To enroll 16 participants, with 8 participants in each of the 2 dose cohorts, 17 participants were screened. Study enrollment occurred between December 16, 2016, and August 17, 2017, at sites in the US and Canada. Data were collected from December 2016 to February 2018, and data were analyzed from April 2018 to May 2019.

Interventions

Participants received 40 mg/kg (low dose) or 80 mg/kg (high dose) of viltolarsen administered by weekly intravenous infusion.

Main Outcomes and Measures

Primary outcomes of the trial included safety, tolerability, and de novo dystrophin protein production measured by Western blot in participants’ biceps muscles. Secondary outcomes included additional assessments of dystrophin mRNA and protein production as well as clinical muscle strength and function.

Results

Of the 16 included boys with DMD, 15 (94%) were white, and the mean (SD) age was 7.4 (1.8) years. After 20 to 24 weeks of treatment, significant drug-induced dystrophin production was seen in both viltolarsen dose cohorts (40 mg/kg per week: mean [range] 5.7% [3.2-10.3] of normal; 80 mg/kg per week: mean [range] 5.9% [1.1-14.4] of normal). Viltolarsen was well tolerated; no treatment-emergent adverse events required dose reduction, interruption, or discontinuation of the study drug. No serious adverse events or deaths occurred during the study. Compared with 65 age-matched and treatment-matched natural history controls, all 16 participants treated with viltolarsen showed significant improvements in timed function tests from baseline, including time to stand from supine (viltolarsen: −0.19 s; control: 0.66 s), time to run/walk 10 m (viltolarsen: 0.23 m/s; control: −0.04 m/s), and 6-minute walk test (viltolarsen: 28.9 m; control: −65.3 m) at the week 25 visit.

Conclusions and Relevance

Systemic treatment of participants with DMD with viltolarsen induced de novo dystrophin production, and clinical improvement of timed function tests was observed.

Trial Registration

ClinicalTrials.gov Identifier: NCT02740972

Seven-Year Experience From the National Institute of Neurological Disorders and Stroke-Supported Network for Excellence in Neuroscience Clinical Trials

Importance

One major advantage of developing large, federally funded networks for clinical research in neurology is the ability to have a trial-ready network that can efficiently conduct scientifically rigorous projects to improve the health of people with neurologic disorders.

Observations

National Institute of Neurological Disorders and Stroke Network for Excellence in Neuroscience Clinical Trials (NeuroNEXT) was established in 2011 and renewed in 2018 with the goal of being an efficient network to test between 5 and 7 promising new agents in phase II clinical trials. A clinical coordinating center, data coordinating center, and 25 sites were competitively chosen. Common infrastructure was developed to accelerate timelines for clinical trials, including central institutional review board (a first for the National Institute of Neurological Disorders and Stroke), master clinical trial agreements, the use of common data elements, and experienced research sites and coordination centers. During the first 7 years, the network exceeded the goal of conducting 5 to 7 studies, with 9 funded. High interest was evident by receipt of 148 initial applications for potential studies in various neurologic disorders. Across the first 8 studies (the ninth study was funded at end of initial funding period), the central institutional review board approved the initial protocol in a mean (SD) of 59 (21) days, and additional sites were added a mean (SD) of 22 (18) days after submission. The median time from central institutional review board approval to first site activation was 47.5 days (mean, 102.1; range, 1-282) and from first site activation to first participant consent was 27 days (mean, 37.5; range, 0-96). The median time for database readiness was 3.5 months (mean, 4.0; range, 0-8) from funding receipt. In the 4 completed studies, enrollment met or exceeded expectations with 96% overall data accuracy across all sites. Nine peer-reviewed manuscripts were published, and 22 oral presentations or posters and 9 invited presentations were given at regional, national, and international meetings.

Conclusions and Relevance

NeuroNEXT initiated 8 studies, successfully enrolled participants at or ahead of schedule, collected high-quality data, published primary results in high-impact journals, and provided mentorship, expert statistical, and trial management support to several new investigators. Partnerships were successfully created between government, academia, industry, foundations, and patient advocacy groups. Clinical trial consortia can efficiently and successfully address a range of important neurologic research and therapeutic questions.

The Minimal Clinical Important Difference (MCID) in Annual Rate of Change of Timed Function Tests in Boys with DMD

BACKGROUND

Duchenne muscular dystrophy (DMD) is a rare x-linked recessive genetic disorder affecting 1 in every 5000-10000 [1, 2]. This disease leads to a variable but progressive sequential pattern of muscle weakness that eventually causes loss of important functional milestones such as the ability to walk. With promising drugs in development to ameliorate the effects of muscle weakness, these treatments must be associated with a clinically meaningful functional change.

OBJECTIVE

The objective of this analysis is to determine both distribution, minimal detectable change (MDC), and anchor-based, minimal clinically important difference, (MCID) of 12 month change values in standardized time function tests (TFT) used to monitor disease progression in DMD.

METHOD

This is a retrospective analysis of prospectively collected data from a multi-center prospective natural history study with the Cooperative International Neuromuscular Research Group (CINRG). This study calculated MDC and MCID values for 3 commonly used timed function tests typically used to monitor disease progression; supine to stand (STS), 10 meter walk/run (10MWT), and 4 stair climb (4SC). MDC used standard error of measurement (SEM) while MCID measurements used the Vignos scale as an anchor to determine clinical change in functional status.

RESULTS

All 3 TFT were significantly important clinical endpoints to detect MDC and MCID changes. MDC and MCID 12 month changes were significant in 10MWT (-0.138, -0.212), Supine to Stand (-0.026, -0.023) and 4 stair climb (-0.034, -0.035) with an effect size greater or close to 0.2.

CONCLUSION

The 3 TFT are clinically meaningful endpoints used to establish change in DMD. MCID values were higher than MDC values indicating that an anchor-based approach using Vignos as a clinically meaningful loss of lower extremity abilities is appropriate to assess change in boys with DMD.

(-)-Epicatechin induces mitochondrial biogenesis and markers of muscle regeneration in adults with Becker muscular dystrophy

Introduction

We conducted an open‐label study to examine the effects of the flavonoid (−)‐epicatechin in seven ambulatory adult patients with Becker muscular dystrophy (BMD).

Methods

Seven participants received (−)‐epicatechin 50 mg twice per day for 8 weeks. Pre‐ and postprocedures included biceps brachii biopsy to assess muscle structure and growth‐relevant endpoints by western blotting, mitochondria volume measurement, and cristae abundance by electron microscopy, graded exercise testing, and muscle strength and function tests.

Results

Western blotting showed significantly increased levels of enzymes modulating cellular bioenergetics (liver kinase B1 and 5′‐adenosine monophosphate–activated protein kinase). Peroxisome proliferator‐activated receptor gamma coactivator‐1alpha, a transcriptional coactivator of genes involved in mitochondrial biogenesis and cristae‐associated mitofilin levels, increased as did cristae abundance. Muscle and plasma follistatin increased significantly while myostatin decreased. Markers of skeletal muscle regeneration myogenin, myogenic regulatory factor‐5, myoblast determination protein 1, myocyte enhancer factor‐2, and structure‐associated proteins, including dysferlin, utrophin, and intracellular creatine kinase, also increased. Exercise testing demonstrated decreased heart rate, maximal oxygen consumption per kilogram, and plasma lactate levels at defined workloads. Tissue saturation index improved in resting and postexercise states.

Discussion

(−)‐Epicatechin, an exercise mimetic, appears to have short‐term positive effects on tissue biomarkers indicative of mitochondrial biogenesis and muscle regeneration, and produced improvements in graded exercise testing parameters in patients with BMD.

Multi-Omics Identifies Circulating miRNA and Protein Biomarkers for Facioscapulohumeral Dystrophy

The development of therapeutics for muscle diseases such as facioscapulohumeral dystrophy (FSHD) is impeded by a lack of objective, minimally invasive biomarkers. Here we identify circulating miRNAs and proteins that are dysregulated in early-onset FSHD patients to develop blood-based molecular biomarkers. Plasma samples from clinically characterized individuals with early-onset FSHD provide a discovery group and are compared to healthy control volunteers. Low-density quantitative polymerase chain reaction (PCR)-based arrays identify 19 candidate miRNAs, while mass spectrometry proteomic analysis identifies 13 candidate proteins. Bioinformatic analysis of chromatin immunoprecipitation (ChIP)-seq data shows that the FSHD-dysregulated DUX4 transcription factor binds to regulatory regions of several candidate miRNAs. This panel of miRNAs also shows ChIP signatures consistent with regulation by additional transcription factors which are up-regulated in FSHD (FOS, EGR1, MYC, and YY1). Validation studies in a separate group of patients with FSHD show consistent up-regulation of miR-100, miR-103, miR-146b, miR-29b, miR-34a, miR-454, miR-505, and miR-576. An increase in the expression of S100A8 protein, an inflammatory regulatory factor and subunit of calprotectin, is validated by Enzyme-Linked Immunosorbent Assay (ELISA). Bioinformatic analyses of proteomics and miRNA data further support a model of calprotectin and toll-like receptor 4 (TLR4) pathway dysregulation in FSHD. Moving forward, this panel of miRNAs, along with S100A8 and calprotectin, merit further investigation as monitoring and pharmacodynamic biomarkers for FSHD.

Medical management of muscle weakness in Duchenne muscular dystrophy

Introduction

Duchenne muscular dystrophy (DMD) is a childhood onset muscular dystrophy leading to shortened life expectancy. There are gaps in published DMD care guidelines regarding recently approved DMD medications and alternative steroid dosing regimens.

Methods

A list of statements about use of currently available therapies for DMD in the United States was developed based on a systematic literature review and expert panel feedback. Panelists’ responses were collected using a modified Delphi approach.

Results

Among corticosteroid regimens, either deflazacort or prednisone weekend dosing was preferred when payer requirements do not dictate choice. Most patients with exon 51 skip-amenable mutations should be offered eteplirsen, before or with a corticosteroid.

Discussion

The options available for medical management of the motor symptoms of DMD are expanding rapidly. The choice of medical therapies should balance expected benefit with side effects.

Meta-analyses of ataluren randomized controlled trials in nonsense mutation Duchenne muscular dystrophy

Aim: Assess the totality of efficacy evidence for ataluren in patients with nonsense mutation Duchenne muscular dystrophy (nmDMD). Materials & methods: Data from the two completed randomized controlled trials (ClinicalTrials.gov: NCT00592553; NCT01826487) of ataluren in nmDMD were combined to examine the intent-to-treat (ITT) populations and two patient subgroups (baseline 6-min walk distance [6MWD] ≥300–<400 or <400 m). Meta-analyses examined 6MWD change from baseline to week 48. Results: Statistically significant differences in 6MWD change with ataluren versus placebo were observed across all three meta-analyses. Least-squares mean difference (95% CI): ITT (n = 342), +17.2 (0.2–34.1) m, p = 0.0473; ≥300–<400 m (n = 143), +43.9 (18.2–69.6) m, p = 0.0008; <400 m (n = 216), +27.7 (6.4–49.0) m, p = 0.0109. Conclusion: These meta-analyses support previous evidence for ataluren in slowing disease progression versus placebo in patients with nmDMD over 48 weeks. Treatment benefit was most evident in patients with a baseline 6MWD ≥300–<400 m (the ambulatory transition phase), thereby informing future trial design.

Efficacy and safety of vamorolone in Duchenne muscular dystrophy: An 18-month interim analysis of a non-randomized open-label extension study

BACKGROUND

Treatment with corticosteroids is recommended for Duchenne muscular dystrophy (DMD) patients to slow the progression of weakness. However, chronic corticosteroid treatment causes significant morbidities. Vamorolone is a first-in-class anti-inflammatory investigational drug that has shown evidence of efficacy in DMD after 24 weeks of treatment at 2.0 or 6.0 mg/kg/day. Here, open-label efficacy and safety experience of vamorolone was evaluated over a period of 18 months in trial participants with DMD.

METHODS AND FINDINGS

A multicenter, open-label, 24-week trial (VBP15-003) with a 24-month long-term extension (VBP15-LTE) was conducted by the Cooperative International Neuromuscular Research Group (CINRG) and evaluated drug-related effects of vamorolone on motor outcomes and corticosteroid-associated safety concerns. The study was carried out in Canada, US, UK, Australia, Sweden, and Israel, from 2016 to 2019. This report covers the initial 24-week trial and the first 12 months of the VBP15-LTE trial (total treatment period 18 months). DMD trial participants (males, 4 to <7 years at entry) treated with 2.0 or 6.0 mg/kg/day vamorolone for the full 18-month period (n = 23) showed clinical improvement of all motor outcomes from baseline to month 18 (time to stand velocity, p = 0.012 [95% CI 0.010, 0.068 event/second]; run/walk 10 meters velocity, p < 0.001 [95% CI 0.220, 0.491 meters/second]; climb 4 stairs velocity, p = 0.001 [95% CI 0.034, 0.105 event/second]; 6-minute walk test, p = 0.001 [95% CI 31.14, 93.38 meters]; North Star Ambulatory Assessment, p < 0.001 [95% CI 2.702, 6.662 points]). Outcomes in vamorolone-treated DMD patients (n = 46) were compared to group-matched participants in the CINRG Duchenne Natural History Study (corticosteroid-naïve, n = 19; corticosteroid-treated, n = 68) over a similar 18-month period. Time to stand was not significantly different between vamorolone-treated and corticosteroid-naïve participants (p = 0.088; least squares [LS] mean 0.042 [95% CI -0.007, 0.091]), but vamorolone-treated participants showed significant improvement compared to group-matched corticosteroid-naïve participants for run/walk 10 meters velocity (p = 0.003; LS mean 0.286 [95% CI 0.104, 0.469]) and climb 4 stairs velocity (p = 0.027; LS mean 0.059 [95% CI 0.007, 0.111]). The vamorolone-related improvements were similar in magnitude to corticosteroid-related improvements. Corticosteroid-treated participants showed stunting of growth, whereas vamorolone-treated trial participants did not (p < 0.001; LS mean 15.86 [95% CI 8.51, 23.22]). Physician-reported incidences of adverse events (AEs) for Cushingoid appearance, hirsutism, weight gain, and behavior change were less for vamorolone than published incidences for prednisone and deflazacort. Key limitations to the study were the open-label design, and use of external comparators.

CONCLUSIONS

We observed that vamorolone treatment was associated with improvements in some motor outcomes as compared with corticosteroid-naïve individuals over an 18-month treatment period. We found that fewer physician-reported AEs occurred with vamorolone than have been reported for treatment with prednisone and deflazacort, and that vamorolone treatment did not cause the stunting of growth seen with these corticosteroids. This Phase IIa study provides Class III evidence to support benefit of motor function in young boys with DMD treated with vamorolone 2.0 to 6.0 mg/kg/day, with a favorable safety profile. A Phase III RCT is underway to further investigate safety and efficacy.

TRIAL REGISTRATION

Clinical trials were registered at www.clinicaltrials.gov, and the links to each trial are as follows (as provided in manuscript text): VBP15-002 [NCT02760264] VBP15-003 [NCT02760277] VBP15-LTE [NCT03038399].

The CINRG Becker Natural History Study: Baseline characteristics

We performed an observational, natural history study of males with in-frame dystrophin gene deletions causing Becker muscular dystrophy (BMD). A prospective natural history study collected longitudinal medical, strength, and timed function assessments. Eighty-three participants with genetically confirmed BMD were enrolled (age range 5.6-75.4 years). Lower extremity function and the percentage of participants who retained ambulation declined across the age span. The largest single group of participants had in-frame deletions that corresponded to an out-of-frame deletion treated with an exon 45 skip to restore the reading frame. This group of 54 participants showed similarities in baseline motor functional assessments when compared to the group of all others in the study. A prospective natural history cohort with in-frame dystrophin gene deletions offers the potential to contribute to clinical trial readiness for BMD and to analyze therapeutic benefit of exon skipping for Duchenne muscular dystrophy.

The care of patients with Duchenne, Becker, and other muscular dystrophies in the COVID-19 pandemic

The coronavirus disease 2019 (COVID-19) pandemic has resulted in the reorganization of health-care settings affecting clinical care delivery to patients with Duchenne and Becker muscular dystrophy (DBMD) as well as other inherited muscular dystrophies. The magnitude of the impact of this public health emergency on the care of patients with DBMD is unclear as they are suspected of having an increased risk for severe manifestations of COVID-19. In this article, the authors discuss their consensus recommendations pertaining to care of these patients during the pandemic. We address issues surrounding corticosteroid and exon-skipping treatments, cardiac medications, hydroxychloroquine use, emergency/respiratory care, rehabilitation management, and the conduct of clinical trials. We highlight the importance of collaborative treatment decisions between the patient, family, and health-care provider, considering any geographic or institution-specific policies and precautions for COVID-19. We advocate for continuing multidisciplinary care for these patients using telehealth.

Suitability of external controls for drug evaluation in Duchenne muscular dystrophy

Objective

To evaluate the suitability of real-world data (RWD) and natural history data (NHD) for use as external controls in drug evaluations for ambulatory Duchenne muscular dystrophy (DMD).

Methods

The consistency of changes in the 6-minute walk distance (Δ6MWD) was assessed across multiple clinical trial placebo arms and sources of NHD/RWD. Six placebo arms reporting 48-week Δ6MWD were identified via literature review and represented 4 sets of inclusion/exclusion criteria (n = 383 patients in total). Five sources of RWD/NHD were contributed by Universitaire Ziekenhuizen Leuven, DMD Italian Group, The Cooperative International Neuromuscular Research Group, ImagingDMD, and the PRO-DMD-01 study (n = 430 patients, in total). Mean Δ6MWD was compared between each placebo arm and RWD/NHD source after subjecting the latter to the inclusion/exclusion criteria of the trial for baseline age, ambulatory function, and steroid use. Baseline covariate adjustment was investigated in a subset of patients with available data.

Results

Analyses included ∼1,200 patient-years of follow-up. Differences in mean Δ6MWD between trial placebo arms and RWD/NHD cohorts ranged from −19.4 m (i.e., better outcomes in RWD/NHD) to 19.5 m (i.e., worse outcomes in RWD/NHD) and were not statistically significant before or after covariate adjustment.

Conclusions

We found that Δ6MWD was consistent between placebo arms and RWD/NHD subjected to equivalent inclusion/exclusion criteria. No evidence for systematic bias was detected. These findings are encouraging for the use of RWD/NHD to augment, or possibly replace, placebo controls in DMD trials. Multi-institution collaboration through the Collaborative Trajectory Analysis Project rendered this study feasible.

Genetic modifiers of respiratory function in Duchenne muscular dystrophy

Objective

Respiratory insufficiency is a major complication of Duchenne muscular dystrophy (DMD). Its progression shows considerable interindividual variability, which has been less thoroughly characterized and understood than in skeletal muscle. We collected pulmonary function testing (PFT) data from a large retrospective cohort followed at Centers collaborating in the Italian DMD Network. Furthermore, we analyzed PFT associations with different DMD mutation types, and with genetic variants in SPP1, LTBP4, CD40, and ACTN3, known to modify skeletal muscle weakness in DMD. Genetic association findings were independently validated in the Cooperative International Neuromuscular Research Group Duchenne Natural History Study (CINRG‐DNHS).

Methods and Results

Generalized estimating equation analysis of 1852 PFTs from 327 Italian DMD patients, over an average follow‐up time of 4.5 years, estimated that forced vital capacity (FVC) declined yearly by −4.2%, forced expiratory volume in 1 sec by −5.0%, and peak expiratory flow (PEF) by −2.9%. Glucocorticoid (GC) treatment was associated with higher values of all PFT measures (approximately + 15% across disease stages). Mutations situated 3’ of DMD intron 44, thus predicted to alter the expression of short dystrophin isoforms, were associated with lower (approximately −6%) PFT values, a finding independently validated in the CINRG‐DNHS. Deletions amenable to skipping of exon 51 and 53 were independently associated with worse PFT outcomes. A meta‐analysis of the two cohorts identified detrimental effects of SPP1 rs28357094 and CD40 rs1883832 minor alleles on both FVC and PEF.

Interpretation

These findings support GC efficacy in delaying respiratory insufficiency, and will be useful for the design and interpretation of clinical trials focused on respiratory endpoints in DMD.