Spinal presentations in children with spinal muscular atrophy type 1 following gene therapy treatment with onasemnogene abeparvovec - The SMA REACH UK network experience.

Spinal muscular atrophy (SMA) is a neuromuscular disorder of mainly early onset and variable severity. Prior to the introduction of disease modifying therapies (DMTs), children with SMA type 1 typically died before 2 years of age and management was primarily palliative. Onasemnogene abeparvovec (OA), nusinersen, and risdiplam are novel DMTs which ameliorate the effects of the underlying genetic defect at least partially making SMA a treatable condition. Survival and achievement of previously unmet developmental milestones result in treated SMA type 1 children spending more time upright than expected based on the natural history of the treatment-naïve condition. Consequently, spinal asymmetry and kyphosis, features not typically seen in untreated SMA type 1 children due to early mortality, are increasingly common complications. Precise data regarding their prevalence, severity, and management are currently limited. This study describes the spinal features and management in 75 children with SMA type 1 who received OA between March 2021 and December 2022. Retrospective analysis from SMA REACH UK data showed that 44/75 (59 %) clinically had spinal asymmetry and 37 (49 %) had kyphosis. This study aims to raise awareness of this important feature as part of the changed natural history of SMA type 1 post OA treatment.

Efficacy and safety of onasemnogene abeparvovec in children with spinal muscular atrophy type 1: real-world evidence from 6 infusion centres in the United Kingdom.

Background: Real-world data on the efficacy and safety of onasemnogene abeparvovec (OA) in spinal muscular atrophy (SMA) are needed, especially to overcome uncertainties around its use in older and heavier children. This study evaluated the efficacy and safety of OA in patients with SMA type 1 in the UK, including patients ≥2 years old and weighing ≥13.5 kg. Methods: This observational cohort study used data from patients with genetically confirmed SMA type 1 treated with OA between May 2021 and January 2023, at 6 infusion centres in the United Kingdom. Functional outcomes were assessed using age-appropriate functional scales. Safety analyses included review of liver function, platelet count, cardiac assessments, and steroid requirements. Findings: Ninety-nine patients (45 SMA therapy-naïve) were treated with OA (median age at infusion: 10 [range, 0.6-89] months; median weight: 7.86 [range, 3.2-20.2] kg; duration of follow-up: 3-22 months). After OA infusion, mean ± SD change in CHOP-INTEND score was 11.0 ± 10.3 with increased score in 66/78 patients (84.6%); patients aged <6 months had a 13.9 points higher gain in CHOP-INTEND score than patients ≥2 years (95% CI, 6.8-21.0; P < 0.001). Asymptomatic thrombocytopenia (71/99 patients; 71.7%), asymptomatic troponin-I elevation (30/89 patients; 33.7%) and transaminitis (87/99 patients; 87.9%) were reported. No thrombotic microangiopathy was observed. Median steroid treatment duration was 97 (range, 28-548) days with dose doubled in 35/99 patients (35.4%). There were 22.5-fold increased odds of having a transaminase peak >100 U/L (95% CI, 2.3-223.7; P = 0.008) and 21.2-fold increased odds of steroid doubling, as per treatment protocol (95% CI, 2.2-209.2; P = 0.009) in patients weighing ≥13.5 kg versus <8.5 kg. Weight at infusion was positively correlated with steroid treatment duration (r = 0.43; P < 0.001). Worsening transaminitis, despite doubling of oral prednisolone, led to treatment with intravenous methylprednisolone in 5 children. Steroid-sparing immunosuppressants were used in 5 children to enable steroid weaning. Two deaths apparently unrelated to OA were reported. Interpretation: OA led to functional improvements and was well tolerated with no persistent clinical complications, including in older and heavier patients. Funding: Novartis Innovative Therapies AG provided a grant for independent medical writing services.

Long-term Natural History of Pediatric Dominant and Recessive RYR1-Related Myopathy.

BACKGROUND AND OBJECTIVES: RYR1-related myopathies are the most common congenital myopathies, but long-term natural history data are still scarce. We aim to describe the natural history of dominant and recessive RYR1-related myopathies. METHODS: A cross-sectional and longitudinal retrospective data analysis of pediatric cases with RYR1-related myopathies seen between 1992-2019 in 2 large UK centers. Patients were identified, and data were collected from individual medical records. RESULTS: Sixty-nine patients were included in the study, 63 in both cross-sectional and longitudinal studies and 6 in the cross-sectional analysis only. Onset ranged from birth to 7 years. Twenty-nine patients had an autosomal dominant RYR1-related myopathy, 31 recessive, 6 de novo dominant, and 3 uncertain inheritance. Median age at the first and last appointment was 4.0 and 10.8 years, respectively. Fifteen% of patients older than 2 years never walked (5 recessive, 4 de novo dominant, and 1 dominant patient) and 7% lost ambulation during follow-up. Scoliosis and spinal rigidity were present in 30% and 17% of patients, respectively. Respiratory involvement was observed in 22% of patients, and 12% needed ventilatory support from a median age of 7 years. Feeding difficulties were present in 30% of patients, and 57% of those needed gastrostomy or tube feeding. There were no anesthetic-induced malignant hyperthermia episodes reported in this cohort. We observed a higher prevalence of prenatal/neonatal features in recessive patients, in particular hypotonia and respiratory difficulties. Clinical presentation, respiratory outcomes, and feeding outcomes were consistently more severe at presentation and in the recessive group. Conversely, longitudinal analysis suggested a less progressive course for motor and respiratory function in recessive patients. Annual change in forced vital capacity was -0.2%/year in recessive vs -1.4%/year in dominant patients. DISCUSSION: This clinical study provides long-term data on disease progression in RYR1-related myopathies that may inform management and provide essential milestones for future therapeutic interventions.

Aquatic therapy for boys with Duchenne muscular dystrophy (DMD): an external pilot randomised controlled trial.

BACKGROUND: Standard treatment of Duchenne muscular dystrophy (DMD) includes regular physiotherapy. There are no data to show whether adding aquatic therapy (AT) to land-based exercises helps maintain motor function. We assessed the feasibility of recruiting and collecting data from boys with DMD in a parallel-group pilot randomised trial (primary objective), also assessing how intervention and trial procedures work. METHODS: Ambulant boys with DMD aged 7-16 years established on steroids, with North Star Ambulatory Assessment (NSAA) score ≥8, who were able to complete a 10-m walk test without aids or assistance, were randomly allocated (1:1) to 6 months of either optimised land-based exercises 4 to 6 days/week, defined by local community physiotherapists, or the same 4 days/week plus AT 2 days/week. Those unable to commit to a programme, with >20% variation between NSAA scores 4 weeks apart, or contraindications to AT were excluded. The main outcome measures included feasibility of recruiting 40 participants in 6 months from six UK centres, clinical outcomes including NSAA, independent assessment of treatment optimisation, participant/therapist views on acceptability of intervention and research protocols, value of information (VoI) analysis and cost-impact analysis. RESULTS: Over 6 months, 348 boys were screened: most lived too far from centres or were enrolled in other trials; 12 (30% of the targets) were randomised to AT (n = 8) or control (n = 4). The mean change in NSAA at 6 months was -5.5 (SD 7.8) in the control arm and -2.8 (SD 4.1) in the AT arm. Harms included fatigue in two boys, pain in one. Physiotherapists and parents valued AT but believed it should be delivered in community settings. Randomisation was unattractive to families, who had already decided that AT was useful and who often preferred to enrol in drug studies. The AT prescription was considered to be optimised for three boys, with other boys given programmes that were too extensive and insufficiently focused. Recruitment was insufficient for VoI analysis. CONCLUSIONS: Neither a UK-based RCT of AT nor a twice weekly AT therapy delivered at tertiary centres is feasible. Our study will help in the optimisation of AT service provision and the design of future research. TRIAL REGISTRATION: ISRCTN41002956.

Aquatic therapy for children with Duchenne muscular dystrophy: a pilot feasibility randomised controlled trial and mixed-methods process evaluation.

BACKGROUND: Duchenne muscular dystrophy (DMD) is a rare disease that causes the progressive loss of motor abilities such as walking. Standard treatment includes physiotherapy. No trial has evaluated whether or not adding aquatic therapy (AT) to land-based therapy (LBT) exercises helps to keep muscles strong and children independent. OBJECTIVES: To assess the feasibility of recruiting boys with DMD to a randomised trial evaluating AT (primary objective) and to collect data from them; to assess how, and how well, the intervention and trial procedures work. DESIGN: Parallel-group, single-blind, randomised pilot trial with nested qualitative research. SETTING: Six paediatric neuromuscular units. PARTICIPANTS: Children with DMD aged 7-16 years, established on corticosteroids, with a North Star Ambulatory Assessment (NSAA) score of 8-34 and able to complete a 10-m walk without aids/assistance. Exclusions: > 20% variation between baseline screens 4 weeks apart and contraindications. INTERVENTIONS: Participants were allocated on a 1 : 1 ratio to (1) optimised, manualised LBT (prescribed by specialist neuromuscular physiotherapists) or (2) the same plus manualised AT (30 minutes, twice weekly for 6 months: active assisted and/or passive stretching regime; simulated or real functional activities; submaximal exercise). Semistructured interviews with participants, parents (n = 8) and professionals (n = 8) were analysed using Framework analysis. An independent rater reviewed patient records to determine the extent to which treatment was optimised. A cost-impact analysis was performed. Quantitative and qualitative data were mixed using a triangulation exercise. MAIN OUTCOME MEASURES: Feasibility of recruiting 40 participants in 6 months, participant and therapist views on the acceptability of the intervention and research protocols, clinical outcomes including NSAA, independent assessment of treatment optimisation and intervention costs. RESULTS: Over 6 months, 348 children were screened - most lived too far from centres or were enrolled in other trials. Twelve (30% of target) were randomised to AT (n = 8) or control (n = 4). People in the AT (n = 8) and control (n = 2: attrition because of parental report) arms contributed outcome data. The mean change in NSAA score at 6 months was -5.5 [standard deviation (SD) 7.8] for LBT and -2.8 (SD 4.1) in the AT arm. One boy suffered pain and fatigue after AT, which resolved the same day. Physiotherapists and parents valued AT and believed that it should be delivered in community settings. The independent rater considered AT optimised for three out of eight children, with other children given programmes that were too extensive and insufficiently focused. The estimated NHS costs of 6-month service were between £1970 and £2734 per patient. LIMITATIONS: The focus on delivery in hospitals limits generalisability. CONCLUSIONS: Neither a full-scale frequentist randomised controlled trial (RCT) recruiting in the UK alone nor a twice-weekly open-ended AT course delivered at tertiary centres is feasible. Further intervention development research is needed to identify how community-based pools can be accessed, and how families can link with each other and community physiotherapists to access tailored AT programmes guided by highly specialised physiotherapists. Bayesian RCTs may be feasible; otherwise, time series designs are recommended. TRIAL REGISTRATION: Current Controlled Trials ISRCTN41002956. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 27. See the NIHR Journals Library website for further project information.

Development of a functional assessment scale for ambulatory boys with Duchenne muscular dystrophy.

BACKGROUND AND PURPOSE: The aims of this study were to develop a clinical assessment scale to measure functional ability in ambulant boys with Duchenne muscular dystrophy and to determine the reliability of the scale in multiple centres in the UK. METHODS: Focus groups and workshops were held with experienced paediatric neuromuscular physiotherapists to determine scale content. A manual was prepared with accompanying videos, and training sessions were conducted. A total of 17 physiotherapists from participating centres used the videos to determine inter-rater reliability. Five determined the intra-rater reliability. RESULTS: Strength of agreement for these groups based on total subject scores was very good (0.95 and ≥ 0.93 for consistency and absolute agreement, respectively). Test-retest ability was high, with perfect agreement between occasions for all but two items of the scale. CONCLUSIONS: Our study indicates that the North Star Ambulatory Assessment is practical and reliable. It takes only 10 minutes to perform and incorporates both universally used timed tests as well as levels of activities, which allow assessment of high-functioning boys with Duchenne muscular dystrophy.