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Introduction/Aims: Eteplirsen, approved in the US for patients with Duchenne muscular dystrophy (DMD) with exon 51 skip‐amenable variants, is associated with attenuated ambulatory/pulmonary decline versus DMD natural history (NH). We report overall survival in a US cohort receiving eteplirsen and contextualize these outcomes versus DMD NH. Methods: US patients with DMD receiving eteplirsen were followed through a patient support program, with data collected on ages at eteplirsen initiation and death/end of follow‐up. Individual DMD NH data were extracted by digitizing Kaplan–Meier (KM) curves from published systematic and targeted literature reviews. Overall survival age was analyzed using KM curves and contextualized with DMD NH survival curves; subanalyses considered age groups and duration of eteplirsen exposure. Overall survival time from treatment initiation was also evaluated. Results: A total of 579 eteplirsen‐treated patients were included. During a total follow‐up of 2119 person‐years, median survival age was 32.8 years. DMD NH survival curves extracted from four publications (follow‐up for 1224 DMD NH controls) showed overall pooled median survival age of 27.4 years. Eteplirsen‐treated patients had significantly longer survival from treatment initiation versus age‐matched controls (age‐adjusted hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.44–0.98; p <.05). Longer treatment exposure was associated with improved survival (HR, 0.15; 95% CI, 0.05–0.41; p <.001). Comparisons using different DMD NH cohorts to address common risks of bias yielded consistent findings. Discussion: Data suggest eteplirsen may prolong survival in patients with DMD across a wide age range. As more data become available, the impact of eteplirsen on survival will be further elucidated. [ABSTRACT FROM AUTHOR]

This study examined functional trajectories of subjects during the transition phase between ambulatory and non-ambulatory Duchenne muscular dystrophy (DMD) to inform clinical trial designs for new therapeutics. Ambulatory, pulmonary, and upper limb function leading up to loss of ambulation (LoA) and non-ambulatory measures following LoA were quantified; time ordering of pulmonary and upper limb milestones relative to LoA were determined; and the 10-second time threshold for 10-meter walk/run (10MWR) as a marker of approaching LOA was explored. Included in this analysis were 51 subjects aged between 7 and 18 years who experienced LoA during follow-up in the PRO-DMD-01 natural history study. Mean age at LoA was 12.7 (7.1–18.6) years. Mean annual rates of decline in forced vital capacity (FVC) <80%-predicted and performance of upper limb (PUL) 1.2 total score were smaller before than after LoA, but not significantly (FVC %-predicted: 5.6% vs. 10.1%, p = 0.21; PUL 1.2 total score: 2.3 vs. 3.8 units, p = 0.20). More than half of patients experienced clinically significant deficits in FVC %-predicted and PUL 1.2 before experiencing LoA. Among subjects with baseline 10MWR >10 s, those with <1 year to LoA had similar mean ages but significantly worse mean ambulatory function at baseline compared to those with ≥1 year to LoA. Enriching DMD clinical trials for patients with declining pulmonary or upper limb function is achievable without restricting enrollment to non-ambulatory patients. The sequencing of LoA and initial deficits in pulmonary and upper limb function varied across patients and highlights the potential for composite outcomes or multi-outcome trial designs to assess disease-modifying therapies more comprehensively. [ABSTRACT FROM AUTHOR]

IntroductionAn international clinical trial enrolled 174 ambulatory males ≥5 years old with nonsense mutation Duchenne muscular dystrophy (nmDMD). Pretreatment data provide insight into reliability, concurrent validity, and minimal clinically important differences (MCIDs) of the 6-minute walk test (6MWT) and other endpoints.MethodsScreening and baseline evaluations included the 6-minute walk distance (6MWD), timed function tests (TFTs), quantitative strength by myometry, the PedsQL, heart rate-determined energy expenditure index, and other exploratory endpoints.ResultsThe 6MWT proved feasible and reliable in a multicenter context. Concurrent validity with other endpoints was excellent. The MCID for 6MWD was 28.5 and 31.7 meters based on 2 statistical distribution methods.ConclusionsThe ratio of MCID to baseline mean is lower for 6MWD than for other endpoints. The 6MWD is an optimal primary endpoint for Duchenne muscular dystrophy (DMD) clinical trials that are focused therapeutically on preservation of ambulation and slowing of disease progression.

IntroductionDuchenne muscular dystrophy (DMD) subjects ≥5 years with nonsense mutations were followed for 48 weeks in a multicenter, randomized, double-blind, placebo-controlled trial of ataluren. Placebo arm data (N = 57) provided insight into the natural history of the 6-minute walk test (6MWT) and other endpoints.MethodsEvaluations performed every 6 weeks included the 6-minute walk distance (6MWD), timed function tests (TFTs), and quantitative strength using hand-held myometry.ResultsBaseline age (≥7 years), 6MWD, and selected TFT performance are strong predictors of decline in ambulation (Δ6MWD) and time to 10% worsening in 6MWD. A baseline 6MWD of

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 [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction: Natural history studies for Duchenne muscular dystrophy (DMD) have not included measures of community ambulation.Methods: Step activity (SA) monitors quantified community ambulation in 42 boys (ages 4-16 years) with DMD with serial enrollment up to 5 years by using a repeated-measures mixed model. Additionally, data were compared with 10-meter walk/run (10mWR) speed to determine validity and sensitivity.Results: There were significant declines in average strides/day and percent strides at moderate, high and pediatric high rates as a function of age (P < 0.05). Significant correlations for 10mWR versus high and low stride rates were found at baseline (P < 0.05). SA outcomes were sensitive to change over 1 year, but the direction and parameter differed by age group (younger vs. older). Changes in strides/day and percentages of high frequency and low frequency strides correlated significantly with changes in 10mWR speed (P < 0.05).Discussion: Community ambulation data provide valid and sensitive real-world measures that may inform clinical trials. Muscle Nerve 57: 401-406, 2018. [ABSTRACT FROM AUTHOR]

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease resulting in severe respiratory derangements. As such, DMD patients are at a high risk of nocturnal hypoventilation, thereby requiring nocturnal ventilation (NV). To this end, NV is an important clinical milestone in the management of DMD. Emerging evidence suggests that ß2 adrenergic receptors (ADRB2) may play a role in determining respiratory function, whereby more functional ADRB2 genotype variants (e.g., Gly16) are associated with improved pulmonary function and respiratory muscle strength. These findings suggest that the more functional ADRB2 genotype may help to preserve respiratory function in patients with DMD. The purpose of this study was to identify the influence of ADRB2 genotype on the risk of NV use in DMD. Data from the CINRG Duchenne Natural History Study including 175 DMD patients (3-25 yrs) were analyzed focusing on ADRB2 genotype variants. Time-to-event analyses were used to examine differences in the age at prescription of full-time NV use between genotypes. There were no differences between genotype groups in age, height, weight, corticosteroid use, proportion of ambulatory patients, or age at loss of ambulation. DMD patients expressing the Gly16 polymorphism had a significantly (P < 0.05) lower mean age at NV prescription compared with those patients expressing the Arg16 polymorphism (21.80 ± 0.59 yrs. vs 25.91 ± 1.31 yrs., respectively). In addition, a covariate-adjusted Cox model revealed that the Gly16 variant group possessed a 6.52-fold higher risk of full-time NV use at any given age compared with the Arg16 polymorphism group. These data suggest that genetic variations in the ADRB2 gene may influence the age at which DMD patients are first prescribed NV, whereby patients with the Gly16 polymorphism are more likely to require NV assistance at an earlier age than their Arg16 counterparts. [ABSTRACT FROM AUTHOR]