Long-term natural history in type II and III spinal muscular atrophy: a 4-year international study on the Hammersmith Functional Motor Scale Expanded.

BACKGROUND AND PURPOSE: Spinal muscular atrophy (SMA) is a genetic disorder caused by SMN1 gene mutations. Although studies on available disease-modifying treatments have reported their efficacy and safety, long-term natural history data are lacking for comparison. The aim of this prospective study was to report 4-year changes on the Hammersmith Functional Motor Scale Expanded (HFMSE) in type II and III SMA in relation to several variables such as age, functional status and SMN2 copy number. METHODS: The study involves retrospective analysis of prospectively collected data from international datasets (Belgium, Italy, Spain, USA, UK). HFMSE longitudinal changes were analyzed using linear mixed effect models, examining annualized HFMSE change and its association with variables such as age at baseline, sex, motor function, SMN2 copy number. RESULTS: In SMA type II (n = 226), the 4-year mean change was -2.20 points. The largest mean changes were observed in sitters aged 5-14 years and the lowest in those who lost the ability to sit unsupported. In SMA type III (n = 162), the 4-year mean change was -2.75 points. The largest mean changes were in those aged 7-15 years, whilst the lowest were in those below 7 and in the SMA type IIIa subgroup over 15. Age and score at baseline were predictive of 4-year changes. CONCLUSIONS: Our findings provide natural history reference data for comparison with long-term follow-up of clinical trials or real-world data, highlighting the need to define patterns of changes in smaller SMA subgroups instead of reporting mean changes across an entire SMA cohort.

Profiling neuroinflammatory markers and response to nusinersen in paediatric spinal muscular atrophy.

Neuroinflammation is an emerging clinical feature in spinal muscular atrophy (SMA). Characterizing neuroinflammatory cytokines in cerebrospinal fluid (CSF) in SMA and their response to nusinersen is important for identifying new biomarkers and understanding the pathophysiology of SMA. We measured twenty-seven neuroinflammatory markers in CSF from twenty SMA children at different time points, and correlated the findings with motor function improvement. At baseline, MCP-1, IL-7 and IL-8 were significantly increased in SMA1 patients compared to SMA2, and were significantly correlated with disease severity. After six months of nusinersen treatment, CSF levels of eotaxin and MIP-1ß were markedly reduced, while IL-2, IL-4 and VEGF-A were increased. The decreases in eotaxin and MIP-1ß were associated with changes in motor scores in SMA1. We also detected a transient increase in MCP-1, MDC, MIP-1α, IL-12/IL-23p40 and IL-8 after the first or second injection of nusinersen, followed by a steady return to baseline levels within six months. Our study provides a detailed profile of neuroinflammatory markers in SMA CSF. Our data confirms the potential of MCP-1, eotaxin and MIP-1ß as new neuroinflammatory biomarkers in SMA1 and indicates the presence of a subtle inflammatory response to nusinersen during the early phase of treatment.

Secondary outcomes of scoliosis surgery in disease-modifying treatment-naïve patients with spinal muscular atrophy type 2 and nonambulant type 3.

INTRODUCTION/AIMS: Available studies on scoliosis surgery in spinal muscular atrophy (SMA) have focused on the primary outcome of the procedure-the correction of the curve-whereas research focusing on secondary outcomes is scarce. We aimed to investigate postsurgical changes in respiratory function, motor function, weight, pain, and satisfaction. METHODS: We retrospectively reviewed the clinical notes of 32 disease-modifying treatment-naïve patients (26 SMA2, 6 nonambulant SMA3). We also performed investigator-developed phone interviews and conducted a focus group with families on postsurgical satisfaction. RESULTS: Mean annual rate of forced vital capacity percent decline improved in SMA2: -3.2% postsurgery versus -6.9% presurgery (p < .001), with similar trajectories in SMA3. Gross motor functional scores (Hammersmith Functional Motor Scale) available in 12/32 dropped immediately after surgery: median loss of 6.5 points, with relatively spared upper limb function. Weight z-scores postsurgery dropped in 16/32, requiring food supplements (5/16); one/16 lost >5% of total weight requiring gastrostomy. Postsurgical pain was frequently reported, especially hip pain (13/32). Overall, 10/10 patients/parents participating in the phone interview rated the procedure as very successful for posture and physical appearance. Nonetheless, 7/10 reported postsurgical pain, reduced mobility, and unmet care needs. The seven patients/parents attending the focus group highlighted lack of intensive physiotherapy programs, occupational therapy assistance, and psychological support as postsurgical unmet care needs. DISCUSSION: This study reports a positive impact of scoliosis surgery on respiratory function and overall satisfaction with posture and physical appearance. The observed negative impact on the other outcomes highlights the importance of multidisciplinary approaches to improve postoperative management.

Relationship between growth and ambulation loss in Duchenne muscular dystrophy boys on steroids.

BACKGROUND AND PURPOSE: Treatment with glucocorticoids (GCs) is part of the standard of care in Duchenne muscular dystrophy, but excess weight gain and height stunting are common side-effects. It is still unclear how these growth-related side-effects affect motor function. METHODS: This retrospective cohort study utilized 2228 observations from 648 participants in the UK NorthStar database who had growth and ambulation data recorded between 2006 and 2020. Joint modelling was used to analyse the effect of longitudinal growth centiles on loss of ambulation with respect to GC type and regimen. RESULTS: Loss of ambulation was observed in 113 patients. National estimates of loss of ambulation age were updated by GC group and showed no significant association between loss of ambulation risk and absolute growth centile. However, yearly drift in weight and/or height centile had an associated risk effect on loss of ambulation. Over a 2-year period, a yearly drift in weight from the 50th to the 75th, 75th to the 90th and 90th to the 95th centile was associated with 138%, 118% and 64% increased risk of loss of ambulation, respectively. Conversely, a 2-year drift in height from the 50th to the 25th, 25th to the 10th and 10th to the 5th centile was associated with 53%, 49% and 35% decreased risk of loss of ambulation, respectively. CONCLUSIONS: Our results suggest a complex relationship between growth and loss of ambulation in Duchenne muscular dystrophy boys on chronic GCs, the first step in understanding the effects of drugs which also affect growth patterns.

Upper limb function changes over 12 months in untreated SMA II and III individuals: an item-level analysis using the Revised Upper Limb Module.

The Revised upper limb module (RULM) has been increasingly used in clinical trials and in clinical settings. The aim of this study was to use the 'shift analysis' to assess the patterns of lost or gained abilities for each item on the RULM in an untreated cohort, stratified by SMA type, age, SMN2 copy number, and motor functional status. The analysis was performed on 222 12-month paired assessments from 129 individuals (115 assessment from type II and 107 from type III) who had at least two assessments at yearly intervals. There was a loss of one or more activities in 54% in type II and in 29% type III. A gain of one or more activities was found in 42% type II and in 22% type III. There were concomitant gains and losses in 27% in SMA II and in 9% in SMA III. Our results, measuring the number of abilities that are lost or gained, provide an additional method of detecting changes that can be used for the interpretation of the longitudinal data collected in treated SMA individuals.

Risk-benefit profile of onasemnogene abeparvovec in older and heavier children with spinal muscular atrophy type 1.

Spinal muscular atrophy (SMA) is an autosomal recessive disorder with progressive muscle atrophy and weakness, caused by biallelic mutations in the survival motor neuron 1 (SNM1) gene. Onasemnogene abeparvovec (OA) is an approved gene replacement therapy for patients with SMA. We report on two patients with SMA type 1, weighing 20 kg, previously treated with Nusinersen, who received OA infusion at 7 years of age. To our knowledge, these two patients are the heaviest treated in the real-world and we describe their different courses after gene therapy, including liver impairment requiring long-term steroid treatment and additional immunosuppression, with only transitory improvement in functional outcomes. Our cases illustrate how careful risk-benefit consideration is required in treating older and heavier SMA patients with OA, especially in view of the multiple treatment choices available for older patients with SMA.

Changes in abilities over the initial 12 months of nusinersen treatment for type II SMA.

Several studies have shown the efficacy of new disease-modifying therapies in slowing down type II SMA progression using the Hammersmith Functional Motor Scale Expanded (HFMSE). This research aims to enhance understanding of activity changes across age groups post-nusinersen treatment using shift analysis, compared with untreated individuals. Retrospective data from the, international SMA consortium (iSMAc) dataset were analyzed, assessing individual item changes over 12 months. Shift analysis was used to determine the gain or loss of abilities, defining "gain" as a positive change between scores from 0 to either 1 or 2 and "loss" as a negative change from either 2 or 1 to 0. The cohort included 130 SMA II patients who underwent 12-month assessments from their first nusinersen dose, with age range between 0.6 and 49.6 years. One-third of the entire cohort experienced at least a loss in one activity, while 60% experienced a gain, particularly notable in children aged 2.5 to 5 years and 5 to 13 years. Overall, the study demonstrates a positive impact of nusinersen treatment on SMA II patients, showing a trend of increased activity gains and decreased probability of ability loss across different age groups.

Therapeutic Role of Nusinersen on Respiratory Progression in Pediatric Patients With Spinal Muscular Atrophy Type 2 and Nonambulant Type 3.

Background and Objectives: Nusinersen has shown significant functional motor benefit in the milder types of spinal muscular atrophy (SMA). Less is known on the respiratory outcomes in patients with nusinersen-treated SMA. The aim of this study was to describe changes in respiratory function in pediatric patients with SMA type 2 and 3 on regular treatment with nusinersen within the iSMAc international cohort and to compare their trajectory with the natural history (NH) data published by the consortium in 2020. Methods: This is a 5-year retrospective observational study of pediatric SMA type 2 and nonambulant type 3 (age ≤18 years) treated with nusinersen. The primary objective was to compare the slopes of decline in forced vital capacity % predicted (FVC% pred.), FVC, and age when FVC dropped below 60% between the treated patients and a control group from the natural history cohort. Data on peak cough flow and the use of noninvasive ventilation (NIV) and cough assist were collected. Results: Data were available for 69 treated patients, 53 were SMA type 2 and 16 type 3. The mean (SD) age at first injection was 8.5 (3.2) and 9.7 (3.7) years, respectively. The median (interquartile range) treatment duration was 1 (0.7; 1.9) and 1.2 (0.9; 1.9) years, respectively. At the time of the first nusinersen injection, 24 of 52 (46%) patients with SMA type 2 and 2 of 16 (13%) patients with SMA type 3 were on NIV. Forty-three of 53 (81%) and 4 of 16 (25%) patients used cough device. FVC% pred. in treated patients with SMA type 2 declined annually by 2.3% vs 3.9% in NH (p = 0.08) and in treated patients with type 3 by 2.6% vs 3.4% NH (p = 0.59). Patients treated reached FVC <60% later than untreated (12.1 vs 10 years, p = 0.05). A higher percentage of treated vs untreated patients maintained FVC% pred. equal/above their baseline after 12 (65% vs 36%) and 24 (50% vs 24%) months, respectively. NIV use among treated did not significantly change throughout 1-year follow-up. Discussion: This study included the largest real-world cohort of pediatric patients with milder SMA types. The results suggest a positive role of nusinersen in delaying the respiratory decline in patients treated longer than 1 year when compared with natural history. Larger cohorts and longer observation are planned. Classification of Evidence: This study provided Class III evidence that nusinersen slows progression for patients with SMA types 2 and 3 compared with a natural history cohort.

Determining minimal clinically important differences in the Hammersmith Functional Motor Scale Expanded for untreated spinal muscular atrophy patients: An international study.

BACKGROUND AND PURPOSE: Spinal muscular atrophy (SMA) is a rare and progressive neuromuscular disorder with varying severity levels. The aim of the study was to calculate minimal clinically important difference (MCID), minimal detectable change (MDC), and values for the Hammersmith Functional Motor Scale Expanded (HFMSE) in an untreated international SMA cohort. METHODS: The study employed two distinct methods. MDC was calculated using distribution-based approaches to consider standard error of measurement and effect size change in a population of 321 patients (176 SMA II and 145 SMA III), allowing for stratification based on age and function. MCID was assessed using anchor-based methods (receiver operating characteristic [ROC] curve analysis and standard error) on 76 patients (52 SMA II and 24 SMA III) for whom the 12-month HFMSE could be anchored to a caregiver-reported clinical perception questionnaire. RESULTS: With both approaches, SMA type II and type III patients had different profiles. The MCID, using ROC analysis, identified optimal cutoff points of -2 for type II and -4 for type III patients, whereas using the standard error we found the optimal cutoff points to be 1.5 for improvement and -3.2 for deterioration. Furthermore, distribution-based methods uncovered varying values across age and functional status subgroups within each SMA type. CONCLUSIONS: These results emphasize that the interpretation of a single MCID or MDC value obtained in large cohorts with different functional status needs to be made with caution, especially when these may be used to assess possible responses to new therapies.

Disease Trajectories in the Revised Hammersmith Scale in a Cohort of Untreated Patients with Spinal Muscular Atrophy types 2 and 3.

Background: Spinal muscular atrophy (SMA) is a neuromuscular disorder characterised by progressive motor function decline. Motor function is assessed using several functional outcome measures including the Revised Hammersmith Scale (RHS). Objective: In this study, we present longitudinal trajectories for the RHS in an international cohort of 149 untreated paediatric SMA 2 and 3 patients (across 531 assessments collected between March 2015 and July 2019). Methods: We contextualise these trajectories using both the Hammersmith Functional Motor Scale Expanded (HFMSE) and Revised Upper Limb Module (RULM). At baseline, this cohort included 50% females and 15% of patients had undergone spinal fusion surgery. Patient trajectories were modelled using a natural cubic spline with age, sex, and random effects for each patient. Results: RHS and HFMSE scores show similar trends over time in this cohort not receiving disease modifying therapies. The results confirm the strong correlation between the RHS and RULM previously observed in SMA types 2 and 3a. Scoliosis surgery is associated with a reduction of 3 points in the RHS, 4.5 points in the HFMSE for the SMA 2 population, and a reduction of 11.8 points in the RHS, and 13.4 points in the HFMSE for the SMA 3a populations. When comparing the RHS and RULM, there is a lower correlation in the type 3a's than the type 2 patients. In the SMA 2 population, there is no significant difference between the sexes in either the RHS or HFMSE trajectories. There is no significant difference in the RULM trajectory in the SMA 2 or 3a participants by sex. Conclusions: This study demonstrates that the RHS could be used in conjunction with other functional measures such as the RULM to holistically detect SMA disease progression. This will assist with fully understanding changes that occur with treatments, further defining trajectories and therapy outcomes.

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.

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.

270th ENMC International Workshop: Consensus for SMN2 genetic analysis in SMA patients 10-12 March, 2023, Hoofddorp, the Netherlands.

The 270th ENMC workshop aimed to develop a common procedure to optimize the reliability of SMN2 gene copy number determination and to reinforce collaborative networks between molecular scientists and clinicians. The workshop involved neuromuscular and clinical experts and representatives of patient advocacy groups and industry. SMN2 copy number is currently one of the main determinants for therapeutic decision in SMA patients: participants discussed the issues that laboratories may encounter in this molecular test and the cruciality of the accurate determination, due the implications as prognostic factor in symptomatic patients and in individuals identified through newborn screening programmes. At the end of the workshop, the attendees defined a set of recommendations divided into four topics: SMA molecular prognosis assessment, newborn screening for SMA, SMN2 copies and treatments, and modifiers and biomarkers. Moreover, the group draw up a series of recommendations for the companies manufacturing laboratory kits, that will help to minimize the risk of errors, regardless of the laboratories' expertise.

Assessment of the upper limb function, strength, and mobility in treatment-naive children with spinal muscular atrophy Types 2 and 3.

INTRODUCTION/AIMS: Current upper limb assessments in pediatric spinal muscular atrophy (SMA) may not adequately capture change with disease progression. Our aim was to examine the relationship between motor function, strength, and hand/finger mobility of the upper limb in treatment-naïve children with SMA Types 2 and 3 to assess new methods to supplement current outcomes. METHODS: The Revised Upper Limb Module (RULM), grip and pinch strength, and hand/finger mobility data were collected from 19 children with SMA Types 2 and 3 aged 5.2-16.9 years over a year. RESULTS: A median loss between 0.5 and 2.5 points in the RULM was seen across all SMA subgroups with the biggest median loss recorded between 10 and 14 years of age. The grip strength loss was -0.06 kg (-4.69 to 3.49; IQR, 1.21); pinch improvement of 0.05 (-0.65 to 1.27; IQR, 0.48); hand/finger mobility test improvement of 4 points (-24 to 14; IQR, 6.75) for the whole cohort. Significant correlations were found between the RULM and grip strength (p < .001), RULM and pinch strength (p < .001), RULM and revised Brooke (p < .001), grip strength and pinch strength (p < .001). DISCUSSION: The combined use of the RULM, dynamometry, and hand mobility provide insight about correlations between function and strength in children with SMA. The RULM and grip strength assessments captured a significant decline in upper limb function, whereas the pinch and finger/hand mobility showed an improvement over the course of 1 year and these results should be considered for future studies.

Risdiplam in Spinal Muscular Atrophy: Safety Profile and Use Through The Early Access to Medicine Scheme for the Paediatric Cohort in Great Britain.

Background: Spinal muscular atrophy (SMA) is a progressive neuromuscular disease caused by mutations in Survival motor neuron 1 (SMN1) gene, leading to reduction in survival motor neuron protein (SMN), key for motor neuron survival and function in the brainstem and spinal cord. Risdiplam is an orally administered SMN2-splicing modifier which increases production of functional SMN protein. Risdiplam was offered in the UK under early access to medicines scheme (EAMS) to SMA type 1 and 2 patients aged 2 months and older, not suitable for authorised treatments from September 2020 to December 2021. Objective: To describe the largest paediatric European real-world set of data on patients' characteristics and short-term safety for risdiplam in Great Britain through EAMS. Methods: We collated data from SMA REACH UK a national clinical and research network for all patients enrolled onto EAMS and assessed all submitted adverse events. Results: Of the 92 patients; 78% were Type 2 SMA, mean age 10.9 years, range 0-17 years. 56 were treatment naïve, 33 previously treated; of these 25 had received nusinersen, 3 previous treatment unknown. Sixty adverse events (AEs) were reported occurring in 34 patients. The commonest were respiratory tract infections and gastrointestinal disturbance. Four life-threatening events were reported with 2 deaths and permanent cessation of risdiplam in 3 patients.Overall, 38/60 AEs were considered unrelated to risdiplam, 10/60 related to risdiplam and for 12/60 causality not specified. Conclusions: This study found a safety profile similar to clinical trials with no new safety concerns identified. With the restricted eligibility of onasemnogene abeparvovec and complications of nusinersen administration, EAMS allowed access or continued treatment to naïve patients or patients no longer suitable for approved medications. Collection of longitudinal data for this complex population is needed, to provide greater insights into risdiplam's role in addressing patients' needs into the future.

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.

Quantifying Variability in Motor Function in Duchenne Muscular Dystrophy: UK Centiles for the NorthStar Ambulatory Assessment, 10 m Walk Run Velocity and Rise from Floor Velocity in GC Treated Boys.

Background Boys with Duchenne Muscular Dystrophy (DMD) display heterogeneous motor function trajectory in clinics, which represents a significant obstacle to monitoring. OBJECTIVE: In this paper, we present the UK centiles for the North Star Ambulatory Assessment (NSAA), the 10 m walk/run time (10MWR) and velocity (10MWRV), and the rise from floor time (RFF) and velocity (RFFV) created from a cohort of glucocorticoid treated DMD boys between the age of 5 and 16 years. METHODS: Participants were included from the UK NorthStar registry if they had initiated steroids (primarily deflazacorts/prednisolone, intermittent/daily) and were not enrolled in an interventional trial. Assessments were included if the participant had a complete NSAA, the timed tests had been completed or the corresponding items were 0, or the participant was recorded as non-ambulant, in which case the NSAA was assumed 0. RESULTS: We analysed 3987 assessments of the NSAA collected from 826 participants. Of these, 1080, 1849 and 1199 were imputed as 0 for the NSAA, RFFV and 10MWRV respectively. The 10th, 25th, 50th, 75th and 90th centiles were presented. The NSAA centiles showed a peak score of 14, 20, 26, 30 and 32 respectively, with loss of ambulation at 10.7, 12.2 and 14.3 years for the 25th, 50th and 75th centiles, respectively. The centiles showed loss of rise from floor at 8.6, 10.1 and 11.9 years and a loss of 10MWR of 0 at 8.9, 10.3 and 13.8 years for the 25th, 50th and 75th centiles, respectively. The centiles were pairwise less correlated than the raw scores, suggesting an increased ability to detect variability in the DMD cohort. CONCLUSIONS: The NSAA, 10MWR and RFF centiles may provide insights for clinical monitoring of DMD boys, particularly in late ambulatory participants who are uniformly declining. Future work will validate the centiles in national and international natural history cohorts.