Natural history of Type 2 and 3 spinal muscular atrophy: 2-year NatHis-SMA study

Newborn Screening for SMA – Can a Wait-and-See Strategy be Responsibly Justified in Patients With Four SMN2 Copies?

Background: Early treatment after genetic newborn screening for SMA significantly improves outcomes in infantile SMA. However, there is no consensus in the SMA treatment community about early treatment initiation in patients with four copies of SMN2. Objective: Approach to a responsible treatment strategy for SMA patients with four SMN2 copies detected in newborn screening. Methods: Inclusion criteria were a history of SMA diagnosed by NBS, age >  12 months at last examination, and diagnosis of four SMN2 copies at confirmatory diagnosis. Results: 21 patients with SMA and four SMN2 copies were identified in German screening projects over a three-year period. In three of them, the SMN2 copy number had to be corrected later, and three patients were lost to follow-up. Eight of the fifteen patients who were subject to long-term follow-up underwent presymptomatic therapy between 3 and 36 months of age and had no definite disease symptoms to date. Five of the other seven patients who underwent a strict follow-up strategy, showed clinical or electrophysiological disease onset between 1.5 and 4 years of age. In two of them, complete recovery was not achieved despite immediate initiation of treatment after the onset of the first symptoms. Conclusion: A remarkable proportion of patients with four copies of SMN2 develop irreversible symptoms within the first four years of life, if a wait-and-see strategy is followed. These data argue for a proactive approach, i.e., early initiation of treatment in this subgroup of SMA patients.

Safety, tolerability, and efficacy of a widely available nusinersen program for Polish children with Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder with limited treatment options. Nusinersen is the first disease-modifying therapy to treat children and adults with SMA. This study aimed to review the safety, tolerability, and efficacy data of a nusinersen treatment program in Polish children. A total of 298 patients aged from 0 to 18 years were included in the nusinersen treatment program in Poland between March 1 and September 20, 2019. All patients were prospectively followed for at least one year. The mean age at treatment onset was 6.9 years. SMA type 1 symptoms were reported in 127 patients (43.5%), SMA type 2 symptoms in 68 cases (23.3%), and SMA type 3 in 93 patients (31.8%). No patient met the inefficiency criteria defined in the program. One year after treatment initiation, all patients assessed by the CHOP-INTEND scale had improved or remained stable. The mean change in CHOP-INTEND score was an increase of 8.9 points between baseline and after one-year treatment (p < 0.001). Except for 2 fatal cases, not related to the treatment, no serious adverse events were reported. The results of our study indicate that treatment with nusinersen is beneficial for children with SMA regardless of their age, baseline functional status, or the number of SMN2 gene copies. Therapy with nusinersen was effective and well tolerated by patients.

Onasemnogene abeparvovec for presymptomatic infants with three copies of SMN2 at risk for spinal muscular atrophy: the Phase III SPR1NT trial

Most children with biallelic SMN1 deletions and three SMN2 copies develop spinal muscular atrophy (SMA) type 2. SPR1NT ( NCT03505099 ), a Phase III, multicenter, single-arm trial, investigated the efficacy and safety of onasemnogene abeparvovec for presymptomatic children with biallelic SMN1 mutations treated within six postnatal weeks. Of 15 children with three SMN2 copies treated before symptom onset, all stood independently before 24 months (P < 0.0001; 14 within normal developmental window), and 14 walked independently (P < 0.0001; 11 within normal developmental window). All survived without permanent ventilation at 14 months; ten (67%) maintained body weight (≥3rd WHO percentile) without feeding support through 24 months; and none required nutritional or respiratory support. No serious adverse events were considered treatment-related by the investigator. Onasemnogene abeparvovec was effective and well-tolerated for presymptomatic infants at risk of SMA type 2, underscoring the urgency of early identification and intervention.

Genetically modified animal models of hereditary diseases for testing of gene-directed therapy

Disease-causing genes have been identified for many severe muscular and neurological genetic disorders. Advances in the gene therapy field offer promising solutions for drug development to treat these life-threatening conditions. Depending on how the mutation affects the function of the gene product, different gene therapy approaches may be beneficial. Gene replacement therapy is appropriate for diseases caused by mutations that result in the deficiency of the functional protein. Gene suppression strategy is suggested for disorders caused by the toxic product of the mutant gene. Splicing modulators, genome editing, and base editing techniques can be applied to disorders with different types of underlying mutations. Testing potential drugs in animal models of human diseases is an indispensable step of development. Given the specific gene therapy approach, appropriate animal models can be generated using a variety of technologies ranging from transgenesis to precise genome editing. In this review, we discuss technologies used to generate small and large animal models of the most common muscular and neurological genetic disorders. We specifically focus on animal models that were used to test gene therapies based on adeno-associated vectors and antisense nucleotides.

Predictive models in SMA II natural history trajectories using machine learning: A proof of concept study

It is known from previous literature that type II Spinal Muscular Atrophy (SMA) patients generally, after the age of 5 years, presents a steep deterioration until puberty followed by a relative stability, as most abilities have been lost. Although it is possible to identify points of slope indicating early improvement, steep decline and relative stabilizations, there is still a lot of variability within each age group and it's not always possible to predict individual trajectories of progression from age only. The aim of the study was to develop a predictive model based on machine learning using an XGBoost algorithm for regression and report, explore and quantify, in a single centre longitudinal natural history study, the influence of clinical variables on the 6/12-months Hammersmith Motor Functional Scale Expanded score prediction (HFMSE). This study represents the first approach to artificial intelligence and trained models for the prediction of individualized trajectories of HFMSE disease progression using individual characteristics of the patient. The application of this method to larger cohorts may allow to identify different classes of progression, a crucial information at the time of the new commercially available therapies.

Patient and Caregiver Treatment Preferences in Type 2 and Non-ambulatory Type 3 Spinal Muscular Atrophy: A Discrete Choice Experiment Survey in Five European Countries

BACKGROUND

Spinal muscular atrophy (SMA) is a rare neuromuscular disease that affects motor neurons, resulting in progressive skeletal muscle weakness and atrophy.

OBJECTIVE

The aim of this study was to examine treatment preferences of patients and caregivers of patients with Type 2 and non-ambulatory Type 3 SMA in the Netherlands, Belgium, Finland, Ireland and Portugal.

METHODS

A discrete choice experiment (DCE) survey was developed to elicit the preferences of adult patients and caregivers regarding different treatment aspects of SMA. This survey built on the design of a similar study undertaken in the UK. The DCE described choice questions in terms of attributes and levels combined using a D-efficient design. The attributes described improvements or worsening in motor and breathing function. The mode of treatment administration (intrathecal injection, single intravenous infusion or regular oral therapy) was described. Treatment risks and side effects related to currently available treatments including risk of liver injury, fatigue, headache, nausea, diarrhoea and rash were described. Lastly, an attribute described whether a treatment had evidence of treatment effectiveness in different SMA types. Participants were recruited via patient advocacy associations to complete an online survey. A clustered conditional logit model was used to estimate treatment preferences.

RESULTS

Participants (n = 65) were 4.8 times and 8.1 times more likely to choose a treatment with stable or improved (vs worse) motor function, respectively. Similarly, participants were 4.3 times and 5.8 times more likely to choose stable or improved (vs worse) breathing function, respectively. Treatments with a risk of liver injury, fatigue, headache and nausea were 1.6 times less likely to be chosen than treatments with a risk of diarrhoea and rash. Treatments with demonstrated effectiveness in Type 1 SMA only were 2.3 times less likely to be chosen than those with demonstrated effectiveness in Types 1-3 SMA. Treatments administered via intrathecal injections were also 1.8 times less likely to be chosen than daily oral treatments.

DISCUSSION

Study results show the importance of improvement as well as stabilisation of motor and breathing function to patients and caregivers, and a preference for oral treatments, treatments with demonstrated effectiveness in Types 2-3 SMA, and avoidance of liver injury risk.

Risdiplam: an investigational motor neuron-2 (SMN-2) splicing modifier for spinal muscular atrophy (SMA)

INTRODUCTION

Spinal muscular atrophy (SMA) is a rare autosomal recessive neuromuscular disease which is characterized by muscle atrophy and early death in most patients. Risdiplam is the third overall and first oral drug approved for SMA with disease-modifying potential. Risdiplam acts as a survival motor neuron 2 (SMN2) pre-mRNA splicing modifier with satisfactory safety and efficacy profile. This review aims to critically appraise the place of risdiplam in the map of SMA therapeutics.

AREAS COVERED

This review gives an overview of the current market for SMA and presents the mechanism of action and the pharmacological properties of risdiplam. It also outlines the development of risdiplam from early preclinical stages through to the most recently published results from phase 2/3 clinical trials. Risdiplam has proved its efficacy in pivotal trials for SMA Types 1, 2, and 3 with a satisfactory safety profile.

EXPERT OPINION

In the absence of comparative data with the other two approved drugs, the role of risdiplam in the treatment algorithm of affected individuals is examined in three different patient populations based on the age and diagnosis method (newborn screening or clinical, symptom-driven diagnosis). Long-term data and real-world data will play a fundamental role in its future.

Bildgebung der Muskulatur bei Neuromuskulären Erkrankungen – von der Initialdiagnostik bis zur Verlaufsbeurteilung

Die bildgebende Diagnostik hat sich zu einem integralen Element der Betreuung von PatientInnen mit neuromuskulären Erkrankungen entwickelt. Als wesentliches Diagnostikum ist hierbei die Magnetresonanztomografie als breit verfügbares und vergleichsweise standardisiertes Untersuchungsverfahren etabliert, wobei die Sonografie der Muskulatur bei hinreichend erfahrenem Untersucher ebenfalls geeignet ist, wertvolle diagnostische Informationen zu liefern. Das CT hingegen spielt eine untergeordnete Rolle und sollte nur bei Kontraindikationen für eine MRT in Erwägung gezogen werden. Zunächst wurde die Bildgebung bei Muskelerkrankungen primär in der Initialdiagnostik unter vielfältigen Fragestellungen eingesetzt. Das Aufkommen innovativer Therapiekonzepte bei verschiedenen neuromuskulären Erkrankungen machen neben einer möglichst frühzeitigen Diagnosestellung insbesondere auch eine multimodale Verlaufsbeurteilung zur Evaluation des Therapieansprechens notwendig. Auch hier wird die Bildgebung der Muskulatur als objektiver Parameter des Therapieerfolges intensiv diskutiert und in Forschung wie Praxis zunehmend verwendet.

How does risdiplam compare with other treatments for Types 1-3 spinal muscular atrophy: a systematic literature review and indirect treatment comparison

Aim: To conduct indirect treatment comparisons between risdiplam and other approved treatments for spinal muscular atrophy (SMA). Patients & methods: Individual patient data from risdiplam trials were compared with aggregated data from published studies of nusinersen and onasemnogene abeparvovec, accounting for heterogeneity across studies. Results: In Type 1 SMA, studies of risdiplam and nusinersen included similar populations. Indirect comparison results found improved survival and motor function with risdiplam versus nusinersen. Comparison with onasemnogene abeparvovec in Type 1 SMA and with nusinersen in Types 2/3 SMA was challenging due to substantial differences in study populations; no concrete conclusions could be drawn from the indirect comparison analyses. Conclusion: Indirect comparisons support risdiplam as a superior alternative to nusinersen in Type 1 SMA.

Stride Velocity 95th Centile: Insights into Gaining Regulatory Qualification of the First Wearable-Derived Digital Endpoint for use in Duchenne Muscular Dystrophy Trials

In 2019, stride velocity 95th centile (SV95C) became the first wearable-derived digital clinical outcome assessment (COA) qualified by the European Medicines Agency (EMA) for use as a secondary endpoint in trials for Duchenne muscular dystrophy. SV95C was approved via the EMA's qualification pathway for novel methodologies for medicine development, which is a voluntary procedure for assessing the regulatory acceptability of innovative methods used in pharmaceutical research and development. SV95C is an objective, real-world digital ambulation measure of peak performance, representing the speed of the fastest strides taken by the wearer over a recording period of 180 hours. SV95C is correlated with traditional clinic-based assessments of motor function and has greater sensitivity to clinical change over 6 months than other wearable-derived stride variables, for example, median stride length or velocity. SV95C overcomes many limitations of episodic, clinic-based motor function testing, allowing the assessment of ambulation ability between clinic visits and under free-living conditions. Here we highlight considerations and challenges in developing SV95C using evidence generated by a high-performance wearable sensor. We also provide a commentary of the device's technical capabilities, which were a determining factor in the regulatory approval of SV95C. This article aims to provide insights into the methods employed, and the challenges faced, during the regulatory approval process for researchers developing new digital tools for patients with diseases that affect motor function.

Body mass index in type 2 spinal muscular atrophy: a longitudinal study

The aim of this retrospective study was to review body mass index (BMI) in a large cohort of Italian pediatric type 2 spinal muscular atrophy (SMA) patients, aged between 0 and 20 years and to establish possible differences in relation to a number of variables such as ventilation, motor function, and survival motor neuron 2 gene copies. Cross-sectional data were collected from 102 patients for a total of 344 visits. Standard growth charts for height and weight were used as reference, with age adjusted BMI calculated using the Center for Disease and Prevention Children's BMI Tool. In the 344 visits, weight ranged between 3.90 and 83 kg, and the BMI between 8.4 and 31.6 with a BMI/age z-scores <  - 2SD present in 28% and BMI/age z-scores >  + 2SD in 9% of the measurements. The BMI/age z-scores were relatively stable < 5 years of age with an increasing number of patients <  - 2SD after the age of 5, and a wider range of BMI/age z-scores after the age of 13. A difference on the BMI/age z-scores was found among the different age subgroups (< 5, 5-12, ≥ 13 years). A multivariate analysis in 58 patients with longitudinal assessments showed that baseline BMI/age z-scores and gender were significantly contributing to the changes while other variables were not.

CONCLUSION

Our results confirm that careful surveillance of weight and BMI/age z-scores is needed in type 2 SMA. Further studies, including assessments of chewing and swallowing and of lean/fat body mass, will help to better understand the possible mechanisms underlying weight issues.

WHAT IS KNOWN

• Feeding difficulties have been reported in a few studies and were invariably found in patients with type 1 SMA. • Type 2 SMA patients often have low BMI with a relevant number of patients requiring tube feeding.

WHAT IS NEW

• Reduction in BMI/age z-score overtime appeared to depend on baseline BMI/age z-score and gender. • Patients with a low BMI/age z-score were at higher risk of developing further reduction.

Technology-outcome measures in neuromuscular disorders: a systematic review

BACKGROUND

Portable and wearable devices can monitor a number of physical performances and have been lately applied to patients with neuromuscular disorders (NMD).

METHODS

We performed a systematic search of literature databases following PRISMA principles, including all studies reporting the use of technological devices for motor function assessment in NMDs from 2000 to 2021. We also summarized the evidence on measurement properties (validity, reliability, responsiveness) of the analyzed technological outcome measures.

RESULTS

One-hundred studies fulfilled the selection criteria, most of them published in the last ten years. We defined four categories that gathered similar technologies: gait analysis tools, for clinical assessment of pace and posture; continuous monitoring of physical activity with inertial sensors, that allow "unsupervised" activity assessment; upper limb evaluation tools, including Kinect-based outcome measures to assess the reachable workspace; and new muscle strength assessment tools, such as Myotools. Inertial sensors have the evident advantage of being applied in the "in-home" setting, which has become especially appealing with the Covid-19 pandemic, although poor evidence from psychometric property assessment and results of the analyzed studies may limit their research application. Both Kinect-based outcome measures and Myotools have been already validated in multicenter studies and different NMDs, showing excellent characteristics for application in clinical trials.

CONCLUSION

This overview is intended to raise awareness on the potential of the different TOMs in the neuromuscular field and be an informative source for the design of future clinical trials, particularly in the era of telemedicine.

Safety and efficacy of once-daily risdiplam in type 2 and non-ambulant type 3 spinal muscular atrophy (SUNFISH part 2): a phase 3, double-blind, randomised, placebo-controlled trial

BACKGROUND

Risdiplam is an oral small molecule approved for the treatment of patients with spinal muscular atrophy, with approval for use in patients with type 2 and type 3 spinal muscular atrophy granted on the basis of unpublished data. The drug modifies pre-mRNA splicing of the SMN2 gene to increase production of functional SMN. We aimed to investigate the safety and efficacy of risdiplam in patients with type 2 or non-ambulant type 3 spinal muscular atrophy.

METHODS

In this phase 3, randomised, double-blind, placebo-controlled study, patients aged 2-25 years with confirmed 5q autosomal recessive type 2 or type 3 spinal muscular atrophy were recruited from 42 hospitals in 14 countries across Europe, North America, South America, and Asia. Participants were eligible if they were non-ambulant, could sit independently, and had a score of at least 2 in entry item A of the Revised Upper Limb Module. Patients were stratified by age and randomly assigned (2:1) to receive either daily oral risdiplam, at a dose of 5·00 mg (for individuals weighing ≥20 kg) or 0·25 mg/kg (for individuals weighing <20 kg), or daily oral placebo (matched to risdiplam in colour and taste). Randomisation was conducted by permutated block randomisation with a computerised system run by an external party. Patients, investigators, and all individuals in direct contact with patients were masked to treatment assignment. The primary endpoint was the change from baseline in the 32-item Motor Function Measure total score at month 12. All individuals who were randomly assigned to risdiplam or placebo, and who did not meet the prespecified missing item criteria for exclusion, were included in the primary efficacy analysis. Individuals who received at least one dose of risdiplam or placebo were included in the safety analysis. SUNFISH is registered with ClinicalTrials.gov, NCT02908685. Recruitment is closed; the study is ongoing.

FINDINGS

Between Oct 9, 2017, and Sept 4, 2018, 180 patients were randomly assigned to receive risdiplam (n=120) or placebo (n=60). For analysis of the primary endpoint, 115 patients from the risdiplam group and 59 patients from the placebo group were included. At month 12, the least squares mean change from baseline in 32-item Motor Function Measure was 1·36 (95% CI 0·61 to 2·11) in the risdiplam group and -0·19 (-1·22 to 0·84) in the placebo group, with a treatment difference of 1·55 (0·30 to 2·81, p=0·016) in favour of risdiplam. 120 patients who received risdiplam and 60 who received placebo were included in safety analyses. Adverse events that were reported in at least 5% more patients who received risdiplam than those who received placebo were pyrexia (25 [21%] of 120 patients who received risdiplam vs ten [17%] of 60 patients who received placebo), diarrhoea (20 [17%] vs five [8%]), rash (20 [17%] vs one [2%]), mouth and aphthous ulcers (eight [7%] vs 0), urinary tract infection (eight [7%] vs 0), and arthralgias (six [5%] vs 0). The incidence of serious adverse events was similar between treatment groups (24 [20%] of 120 patients in the risdiplam group; 11 [18%] of 60 patients in the placebo group), with the exception of pneumonia (nine [8%] in the risdiplam group; one [2%] in the placebo group).

INTERPRETATION

Risdiplam resulted in a significant improvement in motor function compared with placebo in patients aged 2-25 years with type 2 or non-ambulant type 3 spinal muscular atrophy. Our exploratory subgroup analyses showed that motor function was generally improved in younger individuals and stabilised in older individuals, which requires confirmation in further studies. SUNFISH part 2 is ongoing and will provide additional evidence regarding the long-term safety and efficacy of risdiplam.

FUNDING

F Hoffmann-La Roche.

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.

Recombinant Adeno-Associated Virus Serotype 9 Gene Therapy in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease caused by deletion or mutation of the SMN1 gene. It is characterized by a progressive loss of motor neurons resulting in muscle weakness. The disease affects 1 in 11,000 live births and before the era of treatment SMA was a leading genetic cause of mortality in infants. Recently, disease modifying therapies have been introduced in clinical practice. They include intrathecal and oral antisense oligonucleotides binding to pre-mRNA of SMN2 gene and increasing the translation of fully functional SMN protein as well as SMN1 gene replacement therapy. Onasemnogene abeparvovec uses the adeno-associated virus 9 (AAV9) vector to deliver the SMN1 gene. Phase 1 and phase 3 clinical trials showed that a single administration of onasemnogene abeparvovec resulted in improvement of motor functions in the majority of infants with SMA. Currently, phase 3 trials in SMA1 and SMA2 patients, as well as presymptomatic infants diagnosed with SMA, are ongoing. The drug was approved for medical use in the US in 2019, and in Japan and the European Union in 2020. Thus, first real-world data on efficacy and safety of onasemnogene abeparvovec in SMA patients are available.

Home-based gait analysis as an exploratory endpoint during a multicenter phase 1 trial in limb girdle muscular dystrophy type R2 and facioscapulohumeral muscular dystrophy

INTRODUCTION/AIMS

Limb girdle muscular dystrophy type 2B (LGMDR2) and facioscapulohumeral muscular dystrophy (FSHD) are genetic muscular dystrophies with an increasing number of potential therapeutic approaches. The aim of this study is to report the data of exploratory digital outcomes extracted from wearable magneto-inertial sensors used in a non-controlled environment for ambulant patients with FSHD and LGMDR2 in a short-term, multicenter clinical study.

METHODS

Digital outcomes (stride length, stride speed, and walk parameters in a non-controlled environment) were used as exploratory outcomes in the open-label study ATYR1940-C-004 in ambulant patients during the 3 mo of ATYR1940 treatment and 1 mo of follow-up. Activity and gait variables were calculated from the data recorded in 30-day sub-periods using the sensors. For each sub-period, activity and gait parameters were compared between FSHD and LGMDR2 patients. Change from baseline over the 4-mo study period was assessed.

RESULTS

Ten patients (5 FSHD, 5 LGMDR2) were ambulant and compliant for analysis. Gait parameters, but not activity variables, were significantly lower in LGMDR2 compared to FSHD patients at baseline. Longitudinal analyses showed a slight but significant decrease in stride speed at month 4 for all subjects. Activity variables such as total number of strides per day were highly variable from month to month in individual patients, and no visit effects were found for this variable.

DISCUSSION

The present study suggests that home-recorded stride speed constitutes a precise and sensitive outcome in ambulant patients with FSHD and LGMDR2.

Motor function in type 2 and 3 SMA patients treated with Nusinersen: a critical review and meta-analysis

Background

There is an increasing number of papers reporting the real world use of Nusinersen in different cohorts of SMA patients.

Main body

The aim of this paper was to critically review the literature reporting real world data on motor function in type 2 and 3 patients treated with Nusinersen, subdividing the results according to SMA type, age and type of assessment and performing a meta-analysis of the available results. We also report the available data collected in untreated patients using the same measures. Of the 400 papers identified searching for Nusinersen and spinal muscular atrophy, 19 reported motor function in types 2 and 3: 13 in adults, 4 in children and 2 included both. Twelve papers reported untreated patients’ data. All studies reported positive changes on at least one of the functional measures and at every time point while all-untreated cohorts showed negative changes.

Conclusion

Our review suggests that Nusinersen provides a favorable benefit in motor function across a wide range of SMA type 2 and 3 patients over a 10–14 month observation period. Although a direct comparison with studies reporting data from untreated patients cannot be made, the longitudinal changes in the treated cohorts (consistently positive) are divergent from those observed in the untreated cohorts (consistently negative). The difference could be observed both in the global cohorts and in smaller groups subdivided according to age, type or functional status.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-02065-z.

Nusinersen by subcutaneous intrathecal catheter for symptomatic spinal muscular atrophy patients with complex spine anatomy

INTRODUCTION/AIMS

Intrathecal administration of nusinersen is challenging in patients with spinal muscular atrophy (SMA) who have spine deformities or fusions. We prospectively studied the safety and efficacy of nusinersen administration via an indwelling subcutaneous intrathecal catheter (SIC) for SMA patients with advanced disease.

METHODS

Seventeen participants commenced nusinersen therapy between 2.7 and 31.5 years of age and received 9 to 12 doses via SIC. Safety was assessed in all participants. A separate efficacy analysis comprised 11 nonambulatory, treatment-naive SMA patients (18.1 ± 6.8 years) with three SMN2 copies and complex spine anatomy.

RESULTS

In the safety analysis, 14 treatment-related adverse events (AEs) occurred among 12 (71%) participants; all were related to the SIC and not nusinersen. Device-related AEs interfered with 2.5% of nusinersen doses. Four SICs (24%) required surgical revision due to mechanical malfunction with or without cerebrospinal fluid leak (n = 2), and one (6%) was removed due to Staphylococcus epidermidis meningitis. In the efficacy analysis, mean performance on the nine-hole peg test improved in dominant (15.9%, P = 0.012) and nondominant (19.0%, P = 0.008) hands and grip strength increased by 44.9% (P = 0.031). We observed no significant changes in motor scales, muscle force, pulmonary function, or SMA biomarkers. All participants in the efficacy cohort reported one or more subjective improvement(s) in endurance, purposeful hand use, arm strength, head control, and/or speech.

DISCUSSION

For SMA patients with complex spine anatomy, the SIC allows for reliable outpatient administration of nusinersen that results in meaningful improvements in upper limb function, but introduces risks of technical malfunction and iatrogenic infection.

Upper limb disease evolution in exon 53 skipping eligible patients with Duchenne muscular dystrophy

OBJECTIVE

To understand the natural disease upper limb progression over 3 years of ambulatory and non-ambulatory patients with Duchenne muscular dystrophy (DMD) using functional assessments and quantitative magnetic resonance imaging (MRI) and to exploratively identify prognostic factors.

METHODS

Forty boys with DMD (22 non-ambulatory and 18 ambulatory) with deletions in dystrophin that make them eligible for exon 53-skipping therapy were included. Clinical assessments, including Brooke score, motor function measure (MFM), hand grip and key pinch strength, and upper limb distal coordination and endurance (MoviPlate), were performed every 6 months and quantitative MRI of fat fraction (FF) and lean muscle cross sectional area (flexor and extensor muscles) were performed yearly.

RESULTS

In the whole population, there were strong nonlinear correlations between outcome measures. In non-ambulatory patients, annual changes over the course of 3 years were detected with high sensitivity standard response mean (|SRM| ≥0.8) for quantitative MRI-based FF, hand grip and key pinch, and MFM. Boys who presented with a FF<20% and a grip strength >27% were able to bring a glass to their mouth and retained this ability in the following 3 years. Ambulatory patients with grip strength >35% of predicted value and FF <10% retained ambulation 3 years later.

INTERPRETATION

We demonstrate that continuous decline in upper limb strength, function, and MRI measured muscle structure can be reliably measured in ambulatory and non-ambulatory boys with DMD with high SRM and strong correlations between outcomes. Our results suggest that a combination of grip strength and FF can be used to predict important motor milestones.

SMN protein is required throughout life to prevent spinal muscular atrophy disease progression

Spinal muscular atrophy (SMA) is caused by the loss of the survival motor neuron 1 (SMN1) gene function. The related SMN2 gene partially compensates but produces insufficient levels of SMN protein due to alternative splicing of exon 7. Evrysdi™ (risdiplam), recently approved for the treatment of SMA, and related compounds promote exon 7 inclusion to generate full-length SMN2 mRNA and increase SMN protein levels. SMNΔ7 type I SMA mice survive without treatment for ~ 17 days. SMN2 mRNA splicing modulators increase survival of SMN∆7 mice with treatment initiated at postnatal day 3 (PND3). To define SMN requirements for adult mice, SMNΔ7 mice were dosed with a SMN2 mRNA splicing modifier from PND3 to PND40, then dosing was stopped. Mice not treated after PND40 showed progressive weight loss, necrosis, and muscle atrophy after ~ 20 days. Male mice presented a more severe phenotype than female mice. Mice dosed continuously did not show disease symptoms. The estimated half-life of SMN protein is 2 days indicating that the SMA phenotype reappeared after SMN protein levels returned to baseline. Although SMN protein levels decreased with age in mice and SMN protein levels were higher in brain than in muscle, our studies suggest that SMN protein is required throughout the life of the mouse and is especially essential in adult peripheral tissues including muscle. These studies indicate that drugs such as risdiplam will be optimally therapeutic when given as early as possible after diagnosis and potentially will be required for the life of an SMA patient.

E-Health & Innovation to Overcome Barriers in Neuromuscular Diseases. Report from the 1st eNMD Congress: Nice, France, March 22-23, 2019

By definition, neuromuscular diseases are rare and fluctuating in terms of symptoms; patients are often lately diagnosed, do not have enough information to understand their condition and be proactive in their management. Usually, insufficient resources or services are available, leading to patients' social burden. From a medical perspective, the rarity of such diseases leads to the unfamiliarity of the medical staff and caregiver and an absence of consensus in disease assessment, treatment, and management. Innovations have to be developed in response to patients' and physicians' unmet needs.It is vital to improve several aspects of patients' quality of life with a better comprehension of their disease, simplify their management and follow-up, help their caregiver, and reduce the social and economic burden for living with a rare debilitating disease. Database construction regrouping patients' data and symptoms according to specific country registration on data privacy will be critical in establishing a clear consensus on neuromuscular disease treatment.Clinicians also need technological innovations to help them recognize neuromuscular diseases, find the best therapeutic approach based on medical consensus, and tools to follow patients' states regularly. Diagnosis also has to be improved by implementing automated systems to analyze a considerable amount of data, representing a significant step forward to accelerate the diagnosis and the patients' follow up. Further, the development of new tools able to precisely measure specific outcomes reliably is of the matter of importance in clinical trials to assess the efficacy of a newly developed compound.In this context, creation of an expert community is essential to communicate and share ideas. To this end, 97 clinicians, healthcare professionals, researchers, and representatives of private companies from 9 different countries met to discuss the new perspective and challenges to develop and implement innovative tools in the field of neuromuscular diseases.

Normative data on spontaneous stride velocity, stride length, and walking activity in a non-controlled environment

Background

Normative data are necessary for validation of new outcome measures. Recently, the 95th centile of stride speed was qualified by the European Medicines Agency as a valid secondary outcome for clinical trials in subjects with Duchenne muscular dystrophy. This study aims to obtain normative data on spontaneous stride velocity and length in a non-controlled environment and their evolution after 12 months.

Method

Ninety-one healthy volunteers (50 females, 41 males), with a mean age of 16 years and 2 months, were recruited and assessed at baseline and 12 months later. The 4-stair climb, 6-min walk test, 10-m walk test and rise from floor assessments were performed. Stride length, stride velocity, and the distance walked per hour were studied in an everyday setting for one month after each evaluation.

Results

Of the 91 subjects assessed, 82 provided more than 50 h of recordings at baseline; and 73 subjects provided the same at the end of the year. We observed significant positive correlations of the stride length with age and height of participants, and a significant increase of the median stride length in children after the period. In this group, the 95th centile stride velocity was not correlated with age and was stable after one year. All measures but the 10MWT were stable in adults after a one-year period.

Conclusion

This study provides with data on the influence of age, height, and gender on stride velocity and length as well as accounting for natural changes after one year in controls.

Therapies in preclinical and clinical development for Angelman syndrome

Introduction: Angelman syndrome is a rare genetic neurodevelopmental disorder, caused by deficiency or abnormal function of the maternal ubiquitin protein-ligase E3A, known as UBE3A, in the central nervous system. There is no disease-modifying treatment available, but the therapeutic pipeline of Angelman syndrome includes at least 15 different approaches at preclinical or clinical development. In the coming years, several clinical trials will be enrolling patients, which prompted this comprehensive review.Areas covered: We summarize and critically review the different therapeutic approaches. Some approaches attempt to restore the missing or nonfunctional UBE3A protein in the neurons via gene replacement or enzyme replacement therapies. Other therapies aim to induce expression of the normal paternal copy of the UBE3A gene by targeting a long non-coding RNA, the UBE3A-ATS, which interferes with its own expression. Another therapeutic category includes compounds that target molecular pathways and effector proteins known to be involved in Angelman syndrome pathophysiology.Expert opinion: We believe that by 2022-2023, more than five disease-modifying treatments will be simultaneously at clinical testing. However, the are several challenges with regards to safety and efficacy, which need to be addressed. Additionally, there is still a significant unmet need for clinical trial readiness.

Therapeutic interventions for spinal muscular atrophy: preclinical and early clinical development opportunities

INTRODUCTION

Spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative neuromuscular disease that presents primarily in children. Abnormalities in the SMN1 gene cause reduced levels of the survival motor neuron (SMN) protein, while a second gene, SMN2, produces low levels of functional SMN protein. Currently available drugs do not cure, so a significant unmet need remains for patients treated after symptom onset.

AREAS COVERED

Drugs available in the clinic, investigational agents and key questions for researchers are discussed. A pragmatic search of the literature was performed to identify therapies in late stages of preclinical, or in early stages of clinical development. This list was compared to the CureSMA pipeline for completeness. Drugs approved for indications that have potential for impact for SMA were included. These drugs target the primary deficiency in SMN protein or other pathways involved in SMA pathophysiology that are not SMN-protein dependent.

EXPERT OPINION

Children treated after the onset of symptoms continue to have significant disability. Given the heterogeneity of the population phenotype evidenced by variable response to initial therapy, age at treatment onset and the need to demonstrate added value beyond approved therapeutics, the clinical development of new drugs will be challenging.

Prognostic Factors and Treatment-Effect Modifiers in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a rare, progressive neuromuscular disease characterized by loss of motor neurons and muscle atrophy. Untreated infants with type 1 SMA do not achieve major motor milestones, and death from respiratory failure typically occurs before 2 years of age. Individuals with types 2 and 3 SMA exhibit milder phenotypes and have better functional and survival outcomes. Herein, a systematic literature review was conducted to identify factors that influence the prognosis of types 1, 2, and 3 SMA. In untreated infants with type 1 SMA, absence of symptoms at birth, a later symptom onset, and a higher survival of motor neuron 2 (SMN2) copy number are all associated with increased survival. Disease duration, age at treatment initiation, and, to a lesser extent, baseline function were identified as potential treatment‐modifying factors for survival, emphasizing that early treatment with disease‐modifying therapies (DMT) is essential in type 1 SMA. In patients with types 2 and 3 SMA, factors considered prognostic of changes in motor function were SMN2 copy number, age, and ambulatory status. Individuals aged 6–15 years were particularly vulnerable to developing complications (scoliosis and progressive joint contractures) which negatively influence functional outcomes and may also affect the therapeutic response in patients. Age at the time of treatment initiation emerged as a treatment‐effect modifier on the outcome of DMTs. Factors identified in this review should be considered prior to designing or analyzing studies in an SMA population, conducting population matching, or summarizing results from different studies on the treatments for SMA.