Respiratory Needs in Patients with Type 1 Spinal Muscular Atrophy Treated with Nusinersen

Evaluation of inpatient and emergency department healthcare resource utilization and costs pre- and post-nusinersen for the treatment of spinal muscular atrophy using United States claims

Aim: Nusinersen, administered by intrathecal injection at a dose of 12 mg, is indicated across all ages for the treatment of spinal muscular atrophy (SMA). Evidence on real-world healthcare resource use (HRU) and costs among patients taking nusinersen remains limited. This study aimed to evaluate real-world HRU and costs associated with nusinersen use through US claims databases. Patients & methods: Using the Merative™ MarketScan® Research Databases, patients with SMA receiving nusinersen were identified from commercial (January 2017 to June 2020) and Medicaid claims (January 2017 to December 2019). Those likely to have complete information on the date of nusinersen initiation and continuous enrollment 12 months pre- and post-index (first record of nusinersen treatment) were retained. Number and costs (US$ 2020) of inpatient admissions and emergency department (ED) visits, unrelated to nusinersen administration, were evaluated for 12 months pre- and post-nusinersen initiation and stratified by age: pediatric (<18 years) and adult (≥18 years). Results: Overall, 103 individuals treated with nusinersen were retained: 59 were pediatric (mean age [range]: 9 [1-17] years), and 44 were adults (30 [18-63] years). Inpatient admissions decreased by 41% for pediatrics and 67% for adults in the 12 months post-treatment versus the 12 months pre-treatment. Average inpatient admission costs per patient for the pediatric cohort decreased by 63% ($22,903 vs $8466) and by 79% ($13,997 vs $2899) for the adult cohort when comparing the 12 months pre-index with the 12 months post-index period. Total ED visits and ED visit costs decreased by 8% and 35%, respectively, for the overall cohort over the 12-month period pre- and post-index. Conclusion: Using US claims databases, nusinersen treatment in pediatric and adult patients was associated with reductions in HRU and costs over a 12-month period post-treatment initiation relative to the pre-treatment period.

Treatment Options in Spinal Muscular Atrophy: A Pragmatic Approach for Clinicians

Spinal muscular atrophy (SMA) is a rare neurodegenerative neuromuscular disorder with a wide phenotypic spectrum of severity. SMA was previously life limiting for patients with the most severe phenotype and resulted in progressive disability for those with less severe phenotypes. This has changed dramatically in the past few years with the approvals of three disease-modifying treatments. We review the evidence supporting the use of currently approved SMA treatments (nusinersen, onasemnogene abeparvovec, and risdiplam), focusing on mechanisms of action, side effect profiles, published clinical trial data, health economics, and pending questions. Whilst there is robust data from clinical trials of efficacy and side effect profile for individual drugs in select SMA populations, there are no comparative head-to-head clinical trials. This presents a challenge for clinicians who need to make recommendations on the best treatment option for an individual patient and we hope to provide a pragmatic approach for clinicians across each SMA profile based on current evidence.

Integrated Approaches and Practical Recommendations in Patient Care Identified with 5q Spinal Muscular Atrophy through Newborn Screening

In recent years, significant progress has been made in 5q Spinal Muscular Atrophy therapeutics, emphasizing the importance of early diagnosis and intervention for better clinical outcomes. Characterized by spinal cord motor neuron degeneration, 5q-SMA leads to muscle weakness, swallowing difficulties, respiratory insufficiency, and skeletal deformities. Recognizing the pre-symptomatic phases supported by screening and confirmatory genetic tests is crucial for early diagnosis. This work addresses key considerations in implementing 5q-SMA screening within the Brazilian National Newborn Screening Program and explores Brazil's unique challenges and opportunities, including genetic tests, time-to-patient referral to specialized centers, program follow-up, and treatment algorithms. We aim to guide healthcare professionals and policymakers, facilitating global discussions, including Latin American countries, and knowledge-sharing on this critical subject to improve the care for newborns identified with 5q SMA.

Sleep and sleep-related breathing disorders in patients with spinal muscular atrophy: a changing perspective from novel treatments?

Spinal Muscular Atrophy (SMA) is an inherited neuromuscular disorder characterized by progressive muscle weakness and atrophy, resulting from the degeneration of motor neurons in the spinal cord. A critical aspect of SMA is its impact on respiratory function. As the disease progresses, respiratory muscles, in particular intercostal muscles, become increasingly affected, leading to breathing difficulties and respiratory failure. Without intervention, many children with SMA type 1 die from respiratory failure before their second year of life. While assisted ventilation has improved survival, it often results in ventilator dependence. The development of new SMN-augmenting therapies has renewed optimism, but their long-term impact on respiratory function is uncertain, and non-invasive respiratory support remains an important part of SMA management. Despite the importance of respiratory support in SMA, knowledge regarding sleep disorders in this population is limited. This review aims to synthesize existing literature on sleep and sleep-related breathing disorders in patients with SMA, with a focus on SMA type 1. We summarize evidence of sleep-disordered breathing and respiratory failure in SMA, as well as outcomes and survival benefits associated with non-invasive or invasive ventilation with or without pharmacological therapies. We also discuss current knowledge regarding the effects of novel disease-modifying therapies for SMA on respiratory function and sleep. In conclusion, optimal care for children with SMA requires a multidisciplinary approach that includes neurology and respiratory specialists. This review highlights the importance of monitoring sleep and respiratory function in SMA, as well as the potential benefits and challenges associated with assisted ventilation combined with new therapies.

Gene therapy: principles, challenges and use in clinical practice

INTRODUCTION

Gene therapy is an emerging topic in medicine. The first products have already been licensed in the European Union for the treatment of immune deficiency, spinal muscular atrophy, hemophilia, retinal dystrophy, a rare neurotransmitter disorder and some hematological cancers, while many more are being assessed in preclinical and clinical trials.

OBJECTIVE

The purpose of this review is to provide an overview of the core principles of gene therapy along with information on challenges and risks. Benefits, adverse effects and potential risks are illustrated based on the examples of hemophilia and spinal muscular atrophy.

RESULTS

At present, in-vitro and in-vivo gene addition or gene augmentation is the most commonly established type of gene therapy. More recently, more sophisticated and precise approaches such as in situ gene editing have moved into focus. However, all types of gene therapy require long-term observation of treated patients to ensure safety, efficacy, predictability and durability. Important safety concerns include immune reactions to the vector, the foreign DNA or the new protein resulting from gene therapy, and a remaining low cancer risk based on insertional mutagenesis. Ethical and regulatory issues need to be addressed, and new reimbursement models are called for to ease the financial burden that this new treatment poses for the health care system.

CONCLUSION

Gene therapy holds great promise for considerable improvement or even cure of genetic diseases with serious clinical consequences. However, a number of questions and issues need to be clarified to ensure broad accessibility of safe and efficacious products.

Early treatment of type II SMA slows rate of progression of scoliosis

BACKGROUND

Type II spinal muscular atrophy (SMA) often leads to scoliosis in up to 90% of cases. While pharmacological treatments have shown improvements in motor function, their impact on scoliosis progression remains unclear. This study aims to evaluate potential differences in scoliosis progression between treated and untreated SMA II patients.

METHODS

Treatment effect on Cobb's angle annual changes and on reaching a 50° Cobb angle was analysed in treated and untreated type II SMA patients with a minimum 1.5-year follow-up. A sliding cut-off approach identified the optimal treatment subpopulation based on age, Cobb angle and Hammersmith Functional Motor Scale Expanded at the initial visit. Mann-Whitney U-test assessed statistical significance.

RESULTS

There were no significant differences in baseline characteristics between the untreated (n=46) and treated (n=39) populations. The mean Cobb angle variation did not significantly differ between the two groups (p=0.4). Optimal cut-off values for a better outcome were found to be having a Cobb angle <26° or an age <4.5 years. When using optimal cut-off, the treated group showed a lower mean Cobb variation compared with the untreated group (5.61 (SD 4.72) degrees/year vs 10.05 (SD 6.38) degrees/year; p=0.01). Cox-regression analysis indicated a protective treatment effect in reaching a 50° Cobb angle, significant in patients <4.5 years old (p=0.016).

CONCLUSION

This study highlights that pharmacological treatment, if initiated early, may slow down the progression of scoliosis in type II SMA patients. Larger studies are warranted to further investigate the effectiveness of individual pharmacological treatment on scoliosis progression in this patient population.

Evaluation of the therapeutic efficacy and tolerability of current drug treatments on the clinical outcomes of paediatric spinal muscular atrophy type 1: A systematic review

Spinal muscular atrophy (SMA) is a severe hereditary lower motor neuron disorder characterised by degeneration of alpha motor neurons in the spinal cord, resulting in progressive weakness and paralysis of proximal muscles. A systematic literature search was carried out by using PRISMA guidelines and searching through different databases that could provide findings of evidence on the health outcomes of the approved therapies for the management of paediatric SMA type 1 regarding efficacy with follow-up in terms of motor and respiratory functions and the tolerability and incidence of adverse drug reactions (ADRs) post-treatment from real-world publications. Half of the publications (50%) had a prospective observational design. Eight studies (66.7%) assessed nusinersen, and three studies (25%) assessed onasemnogene abeparvovec with a duration of follow-up ranging from 6 months to 3 years to evaluate the motor and respiratory functions using different assessment tools, hospitalisation rates, and the tolerability and incidence of ADRs post-treatment. The three currently approved treatments for SMA type 1 provided good support and health outcomes in terms of motor function, respiratory outcomes, reduction of hospitalisations, and improvement of survival. Nevertheless, uncertainties regarding continued improvement after long-term illness and the generalizability of results are still unknown.

Sleep architecture and Nusinersen therapy in children with Spinal Muscular Atrophy type 1

BACKGROUND

Spinal muscular atrophy (SMA) is a severe neuromuscular disorder, the phenotype of the disease is caused by the mutation of the SMN1 (survival motor neuron 1) gene which encodes for the SMN protein. Innovative treatments for SMA have become available and the first molecule approved is Nusinersen, an antisense oligonucleotide that increases the production of SMN protein. Nusinersen has been shown to be associated with a significant motor improvement and an increase of the event-free survival. For these reasons the aim of the present study is to assess if Nusinersen is able modify sleep architecture and microstructure and to improve sleep structure in these patients.

METHODS

Sixteen patients affected by SMA1 were enrolled in the study (4 boys, 12 girls; median age 72.5 months, intelligence quotient range 24-84). All patients underwent complete nocturnal PSG before the start of the treatment trough intrathecal injections with Nusinersen (T0) and after the fifth infusion (day 180, T180). PSG recordings were visually scored and interpreted according to the indications of the American Academy of Sleep Medicine (AASM) and and microstructure by means of the Cyclic Alternating Pattern (CAP).

RESULTS

After 6 months therapy we found a significantly reduced sleep latency and a significantly increased sleep efficiency. Regarding sleep microstructure parameters (CAP), we did not find any significant change after therapy however, it is worth mentioning that a moderate effect size was observed for the increase in CAP A3 index.

CONCLUSIONS

We observed short-term effects of Nusinersen on sleep with an improvement in sleep efficiency and reduction in sleep onset latency; regarding sleep microstructure, a moderate effect size was found for the number of CAP A3 subtypes that slightly increased, possibly indicating a slightly higher arousability. This finding points at a probably overall better sleep pattern organization associated with the treatment, but they need to be confirmed by larger studies with patients treated earlier in life and for a longer period.

Safety and effectiveness of nusinersen, a treatment for spinal muscular atrophy, in 524 patients: results from an interim analysis of post-marketing surveillance in Japan

PURPOSE

Nusinersen is an antisense oligonucleotide approved for the treatment of spinal muscular atrophy (SMA). A post-marketing surveillance (PMS) has been ongoing (August 2017-August 2025) in all patients in Japan who were administered nusinersen intrathecally in real-world clinical settings. We report the interim analysis results for safety and effectiveness.

METHODS

This interim analysis was conducted using data collected from 524 patients whose case report forms were obtained at least once by May 30, 2022. Collected data included patient demographics and adverse events (AEs) for safety, and motor function assessments and Clinical Global Impressions of Improvement (CGI-I) for effectiveness.

RESULTS

Of the 524 patients in the safety analysis set, 522 patients who were diagnosed with SMA were included in the effectiveness analysis (infantile-onset SMA [n = 153, 29.3%], later-onset SMA [n = 369, 70.7%]). The median duration of treatment was 785.0 (range 1-1549) days. AEs occurred in 35.9% of patients (49.0% in infantile-onset SMA and 30.6% in later-onset SMA). Nusinersen treatment significantly improved Hammersmith Infant Neurological Examination scores in patients with infantile-onset SMA and Hammersmith Functional Motor Scale-Expanded scores in patients with later-onset SMA for up to nearly 3 years. Based on CGI-I assessments, 98.5-100% of patients receiving nusinersen 'improved' or remain 'unchanged'.

CONCLUSIONS

This interim analysis of the large-scale, all-case PMS in patients who were administered nusinersen in Japan supports the safety and effectiveness of nusinersen. The benefit-risk balance of nusinersen treatment remains favorable.

Respiratory and sleep outcomes in children with SMA treated with nusinersen - real world experience

It is unclear how improvements in peripheral motor function in children with spinal muscular atrophy (SMA), treated with nusinersen, translate into clinically significant respiratory/sleep outcomes. A retrospective chart review of SMA children at the Sydney Children's Hospital Network was undertaken looking at 2 years before and after receiving their first dose of nusinersen. Polysomnography (PSG), spirometry and clinical data were collected and analysed using paired and unpaired t-tests for PSG parameters and generalised estimating equations for longitudinal lung function data. Forty-eight children (10 Type 1, 23 Type 2, 15 Type 3) at mean age 6.98 yrs (SD 5.25) for nusinersen initiation were included. There was a statistically significant improvement in oxygen nadir during sleep in individuals post nusinersen (mean of 87.9% to 92.3% (95%CI 1.24 - 7.63, p = 0.01)). Based on clinical and PSG findings, 6/21 patients (5 Type 2, 1 Type 3) ceased nocturnal NIV post nusinersen. Non-significant improvements were demonstrated in mean slope for FVC% predicted, FVC Z-score and mean FVC% predicted. Within 2 years of commencing nusinersen, stabilisation of respiratory outcomes occurred. Whilst some of the SMA type 2/3 cohort ceased NIV, there were no statistically significant improvements lung function and most PSG parameters.

New therapies for spinal muscular atrophy: where we stand and what is next

The natural history of spinal muscular atrophy has been radically changed by the advent of improved standards of care and the availability of disease-modifying therapies. The aim of this paper is to provide the current therapeutic scenario including new perspectives and to report the challenges related to new phenotypes a few years after the therapies have become available. The paper also includes a review of real-world data that provides information on safety and efficacy in individuals that were not included in clinical trials. Special attention is paid to future perspectives both in terms of new drugs that are currently investigated in clinical trials or providing details on current developments in the use of the available drugs, including combination therapies or new modalities of dose or administration.  Conclusion: Clinical trials and real world data support the efficacy and safety profiles of the available drugs. At the moment there is not enough published evidence about the superiority of one product compared to the others. What is Known: • Safety and efficacy results of clinical trials have led in the last 6 years to the marketing of three drugs for spinal muscular atrophy, with different mechanisms of action. What is New: • Since the drug's approval, real-world data allow us to have data on bigger and heterogeneous groups of patients in contrast with those included in clinical trials. • In addition to the new molecules, combinations of therapies are currently being evaluated.

Evaluation of sputum cultures in children with spinal Muscular atrophy

BACKGROUND

Spinal Muscular Atrophy (SMA) is a severe neuromuscular disorder. Despite increased survival due to novel therapies, morbidity from respiratory complications still persists. We aim to describe these patients' sputum cultures as an expression of chronic infectious airway disease.

METHODS

Retrospective review of medical records of all children with SMA followed at the multidisciplinary respiratory neuromuscular clinic at Schneider Childrens' Medical Center of Israel over a 16-year period. Sputum cultures were obtained during routine visits or pulmonary exacerbations.

RESULTS

Sixty-one SMA patients, aged 1 month to 21 years, were included in this cohort. Of these, sputum cultures were collected from 41 patients. Overall, 288 sputum cultures were obtained, and 98 (34%) were negative for bacterial growth. For the first culture taken from each patient, 12 out of 41 (29%) were sterile. The most common bacteria were pseudomonas aeruginosa (PSA) (38%) and staphylococcus aureus (19.6%). PSA was found in SMA type I patients more frequently than in type II patients (15/26 = 58% vs 4/13 = 31%, p < 0.001). PSA infection was positively associated with noninvasive ventilation, recurrent atelectasis, recurrent pneumonias, swallowing difficulties, but no significant association was found with cough assist machine usage. The incidence of positive cultures did not differ between those treated with Onasemnogene abeparvovec or Nusinersen compared to those without treatment, but the age of first PSA isolation was slightly older with Nusinersen treatment (p = 0.01).

CONCLUSIONS

Airway bacterial colonization is common in SMA type I patients and is not decreased by Onasemnogene abeparvovec or Nusinersen treatment.

Effect of nusinersen on motor, respiratory and bulbar function in early-onset spinal muscular atrophy

5q-associated spinal muscular atrophy is a rare neuromuscular disorder with the leading symptom of a proximal muscle weakness. Three different drugs have been approved by the European Medicines Agency and Food and Drug Administration for the treatment of spinal muscular atrophy patients, however, long-term experience is still scarce. In contrast to clinical trial data with restricted patient populations and short observation periods, we report here real-world evidence on a broad spectrum of patients with early-onset spinal muscular atrophy treated with nusinersen focusing on effects regarding motor milestones, and respiratory and bulbar insufficiency during the first years of treatment. Within the SMArtCARE registry, all patients under treatment with nusinersen who never had the ability to sit independently before the start of treatment were identified for data analysis. The primary outcome of this analysis was the change in motor function evaluated with the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders and motor milestones considering World Health Organization criteria. Further, we evaluated data on the need for ventilator support and tube feeding, and mortality. In total, 143 patients with early-onset spinal muscular atrophy were included in the data analysis with a follow-up period of up to 38 months. We observed major improvements in motor function evaluated with the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders. Improvements were greater in children >2 years of age at start of treatment than in older children. 24.5% of children gained the ability to sit independently. Major improvements were observed during the first 14 months of treatment. The need for intermittent ventilator support and tube feeding increased despite treatment with nusinersen. Our findings confirm the increasing real-world evidence that treatment with nusinersen has a dramatic influence on disease progression and survival in patients with early-onset spinal muscular atrophy. Major improvements in motor function are seen in children younger than 2 years at the start of treatment. Bulbar and respiratory function needs to be closely monitored, as these functions do not improve equivalent to motor function.

Respiratory characteristics in children with spinal muscular atrophy type 1 receiving nusinersen

BACKGROUND

Spinal muscular atrophy type 1 (SMA1) is a neuromuscular disorder with a natural history of chronic respiratory failure and death during infancy without ventilation. Recently, disease-modifying therapies such as nusinersen have improved disease trajectory. However, objective data on the trajectory of polysomnography outcomes, the relationship between motor scores and respiratory parameters, respiratory technology dependence and healthcare utilization in children with SMA1 remain to be elucidated.

METHODS

This was a retrospective observational study of children with SMA1 receiving nusinersen between October 2016 and February 2021 at two tertiary care hospitals in Canada. Baseline polysomnography data, motor scores, respiratory technology, and unanticipated healthcare utilization were examined.

RESULTS

Eleven children (five females, two SMN2 copies each) were included. Median (interquartile range [IQR]) age at diagnosis was 3.6 (2.8-5.0) months and age at diagnostic polysomnogram following nusinersen initiation was 9.4 (5.3-14.0) months. Nusinersen was initiated at a median (IQR) age of 5.4 (3.4-7.6) months and 8/11 children had respiratory symptoms at that time. Diagnostic polysomnography data showed a median (IQR) central apnea-hypopnea index (AHI) of 4.1 (1.8-10.0) and obstructive AHI of 2.2 (0-8.0) events/h. We observed an inverse relationship between motor scores and central apnea-hypopnea indices. All children required ventilatory support at the end of the study period.

CONCLUSION

This study showed abnormal polysomnography parameters and need for ventilation despite nusinersen suggesting ongoing need for regular monitoring with polysomnography. Understanding the respiratory disease trajectory of children undergoing treatment with nusinersen will inform decision-making regarding optimal timing of ventilatory support initiation.

Successful weaning from the invasive respiratory support after nusinersen treatment in a child with SMA type 1: A case report

BACKGROUND

Spinal muscular atrophy (SMA) is an autosomal recessive disease, which can be classified into 4 types according to the symptom onset age and the highest physical developmental milestone. Among them, type 1 SMA is the most severe form that affects infants younger than 6 months. Permanent assisted ventilation is usually needed for infants with type 1 SMA before the age of 2 years due to the rapid progression of disease. Nusinersen can improve the motor function of SMA patients, but its effect on respiratory function varies. In the present study, we reported a case of child with type 1 SMA who was successfully weaned from the invasive respiratory support after nusinersen treatment.

CASE PRESENTATION

A girl aged 6 years and 5 months was admitted for SMA in the Children's Hospital of Nanjing Medical University for 18 times. She received the first administration of nusinersen in November 2020 at the age of 5 years and 1 month. At the age of 6 years and 1 month following 6 loading doses, we tried to wean the child from the invasive ventilation for non-invasive respiratory support using a nasal mask. At present, the patient shows oxygen saturation (SpO₂) above 95% without ventilator support during the daytime, and no signs of dyspnea. A non-invasive home ventilator was used at nighttime for the sake of safety. The CHOP INTEND score increased by 11 points from the first loading dose to the sixth. She can now move her limbs against gravity, take in food orally and perform partial vocal function.

CONCLUSIONS

We reported a child with type 1 SMA who was successfully weaned from the 2-years invasive ventilation after 6 loading doses, and now only need non-invasive ventilation 12 h per day. It is suggested that even a late nusinersen treatment can improve respiratory and motor function in SMA patients, and wean them from mechanical ventilation, thus improve the quality of life and reduce the medical cost.

Open-labelled study to monitor the effect of an amino acid formula on symptom management in children with spinal muscular atrophy type I: The SMAAF pilot study

BACKGROUND

An increasing number of families with children who have spinal muscular atrophy (SMA) are incorporating a special amino acid diet into their child's feeding regimens. Characteristics of the diet include high-carbohydrate and low-fat content with added probiotics. However, because of insufficient evidenced-based research, clinicians are unable to prescribe or endorse this diet. Our aim was to assess the tolerability of an adapted version of the traditional amino acid diet in children with SMA type I.

METHODS

Children with SMA type I were recruited if they were enterally fed and experienced at least one gastrointestinal symptom (reflux, vomiting, constipation, and/or diarrhea). Children were transitioned to an amino acid formula (Neocate Syneo-Nutricia) for 8 weeks. Feeding tolerance was measured weekly by telephone consultation to monitor reflux, vomiting, stool consistency, and frequency.

RESULTS

Fourteen children were recruited, the mean age was 4.1 years (±1.2 SD), and 64% of participants were female. The mean resting energy expenditure determined by indirect calorimetry was 51.5 kcal/kg (±7 SD). The most common gastrointestinal complaint before switching to the amino acid formula was constipation, which was reported in 12 of 14 (85%) patients, of which 10 of the 12 (83%) children required daily stool softeners/laxatives to help regulate bowel function. After 8 weeks on the amino acid formula, 10 out of 12 (83%) children stopped or reduced constipation medication.

CONCLUSION

Children with SMA type I who display gastrointestinal symptoms such as constipation and reflux may benefit from an amino acid formula that is fortified with probiotics.

Population-based assessment of nusinersen efficacy in children with spinal muscular atrophy: a 3-year follow-up study

Nusinersen (Spinraza®) improves survival of infants with hereditary proximal spinal muscular atrophy and motor function in children up to 12 years. Population-based assessments of treatment efficacy are limited and confined to select cohorts of patients. We performed a nationwide, population-based, single-centre cohort study in children with spinal muscular atrophy younger than 9.5 years at start of treatment in line with reimbursement criteria in the Netherlands. We assessed age-relevant motor function scores, the need for tube feeding, hours of ventilatory support and documented adverse events. We used linear mixed modelling to assess treatment effects. We compared motor function during treatment with natural history data and to individual trajectories of muscle strength and motor function before the start of treatment. We included 71 out of 72 Dutch children who were treated (median age 54 months; range 0–117) and followed them for a median of 38 months (range 5–52). We observed improvement of motor function in 72% and stabilization in another 18% of the symptomatic children, which differed from the natural disease course in a matched cohort of which we had previously collected natural history data. Longitudinal analysis showed that motor function improved up to a median of 24 months (range 12–30) of treatment after which it stabilized. Shorter disease duration at start of treatment resulted in better treatment efficacy (P < 0.01). Sixteen children (23%) achieved new motor milestones. Bulbar and respiratory function did not improve significantly during treatment. In 15 patients from whom treatment-naïve data were available, the pre-treatment trajectory of motor function decline changed to stabilization or improvement after the start of treatment. We documented 82 adverse events after 934 injections (9%) in 45 patients. None of the adverse events led to treatment discontinuation. Intrathecal nusinersen treatment is safe and improves or stabilizes motor function in 90% of young children with spinal muscular atrophy types 1c–3a. We did not observe improvement of respiratory and bulbar functions.

Exploratory evaluation of an eye-tracking system in patients with advanced spinal muscular atrophy type I receiving nusinersen

Objective

This study evaluated the feasibility of a matching-pair test using eye-tracking technology to assess nusinersen effectiveness in patients with advanced spinal muscular atrophy (SMA) type I.

Methods

This prospective, observational study enrolled patients with 5q-SMA type I who had lost gross motor function. Three different levels of matching-pair tests were conducted using the eye-gaze system (My Tobii; TobiiDynavox Inc.) at baseline, and after 9 and 24 weeks of nusinersen treatment. The primary endpoint was the change from baseline in matching-pair test scores and response times (i.e., the time to answer matching-pair test) at 24 weeks from baseline. Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND), Pediatric Quality of Life inventory for patients with Neuromuscular Disease (PedsQL-NM) and Numerical Rating Scale (NRS) scores were also assessed as secondary endpoints. Analysis of ocular fixation was performed as an additional analysis. This study was registered at https://www.umin.ac.jp/ctr/ (UMIN000033935).

Results

Seven patients (one male, six female) aged 5–21 years (median 11 years) were enrolled; all patients were bedridden and six patients were ventilated. All seven patients were able to conduct level 1 matching-pair tests at each assessment; five patients were also able to conduct levels 2 and 3. Two patients (those with the highest CHOP-INTEND scores) were able to complete all tests correctly within 60 s. There was a non-significant trend toward improvement in CHOP-INTEND, PedsQL-NM, and NRS scores over the 6-month period. There were no significant differences in the number of actions, errors, correct answers, or response times between baseline and Week 9 or 24 at any level. However, the result of an additional analysis suggests that detection of eye movement would be useful to evaluate for advanced SMA.

Conclusions

Eye-tracking systems are possibly feasible for the assessment of treatment efficacy in patients with advanced SMA type I.

Oral and Swallowing Abilities Tool (OrSAT) in nusinersen treated patients

INTRODUCTION

The aim of the study was to longitudinally assess swallowing abilities in nusinersen-treated patients with type 1 spinal muscular atrophy.

METHODS

Twenty infants with type 1 SMA (11 female and 9 male) treated with nusinersen between 3 weeks and 15 months of age, were assessed using the Oral and Swallowing Abilities Tool (OrSAT). The duration of the follow-up after treatment ranged between 12 months and 62 months.

RESULTS

Twelve of the 20 infants had normal swallowing and there was no need for tube feeding at the time treatment started. Ten of the 12 had consistently normal swallowing with no need for tube feeding on follow-up. The other two required tube feeding but they regained the ability to eat some food by mouth.The remaining 8 infants already had tube feeding inserted at the time treatment started: 4 of them also had tracheostomy and they showed no changes on the OrSAT Scale. The other 4 who had tube feeding but no tracheostomy had partial functional improvement.

CONCLUSION

Our results suggest that the degree of functional impairment at the time treatment is started can help to predict the progression of swallowing abilities. The use of a structured assessment also helped to detect partial improvements.

Changes in Ventilatory Support Requirements of Spinal Muscular Atrophy (SMA) Patients Post Gene-Based Therapies

Spinal muscular atrophy (SMA) is a genetic neuromuscular disease resulting in global muscular weakness and, frequently, in respiratory failure and premature death. Gene-based therapies like Nusinersen are now available for patients with SMA. The aim of this review was to assess in "real world" studies, whether novel treatments would have a positive impact on the mechanical ventilatory support requirements of SMA patients, already initiated on ventilatory support prior to treatment administration. A literature search was performed in Pubmed using multiple combinations of MESH terms and the snowball procedure. A total of 14 publications were discussed in this review. Considering all patients included in the published studies who were on ventilatory support and were treated with Nusinersen, 13/172 (7.5%) had reduced needs for ventilatory support, 1/172 (0.6%) did not need ventilation post-treatment, and 122/172 (70.9%) were maintained on the same ventilator settings. Moreover, 2/41 (4.9%) children who were offered gene therapy had no need for further ventilatory support and 12/41 (29.2%) had reduced requirements. In conclusion, available evidence suggests that among children with SMA, who are on mechanical respiratory support either noninvasively or via tracheostomy at the time of gene-based treatment, only a few will be weaned off the ventilator or have reduced ventilator needs per 24 h. Children will usually require the same level of support as before treatment.

Evolution of bulbar function in spinal muscular atrophy type 1 treated with nusinersen

AIM

To assess the evolution of bulbar function in nusinersen-treated spinal muscular atrophy type 1 (SMA1).

METHOD

This single-centre retrospective study identified 24 patients (14 females and 10 males) with SMA1, treated with nusinersen between 2017 and 2020. We adapted and validated the Paediatric Functional Oral Intake Scale (p-FOIS), which is an outcome measure to assess bulbar function. Analysis considered SMA1 subtype, nutritional support, and Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) and p-FOIS scores at initiation of nusinersen treatment (baseline) and at 6, 12, and 24 months after initiation.

RESULTS

The median age at baseline was 11 months (range 1 month-7 years 6 months). Median age at initiation of tube feeding was 8 months (range 0-2 years 2 months). Fourteen patients were tube fed at baseline. The median p-FOIS score was 3 at baseline and 2 at 12 and 24 months. Four patients, all with type 1c SMA, remained orally fed at 24 months. Median CHOP INTEND scores increased from 32 at baseline to 42 at 12 and 24 months.

INTERPRETATION

Impaired bulbar function persisted as a significant complication in most nusinersen-treated patients with SMA1, in contrast to the improvement in motor abilities demonstrated in the majority. p-FOIS allows for tracking of bulbar function progression and treatment response. Larger, prospective studies investigating the longer-term impacts of nusinersen on bulbar function are warranted.

Scoliosis in Spinal Muscular Atrophy Type 1 in the Nusinersen Era

Background and Objectives

The introduction of spinal muscular dystrophy (SMA)-modifying therapies, such as antisense oligonucleotide therapy, has changed the natural history of SMA. Most reports on treatment outcomes have focused on motor scores and respiratory function. The objective of this study is to document the development and progression of scoliosis in patients with SMA1 treated with nusinersen.

Methods

A descriptive single-center study was conducted in patients with SMA1 who were treated with nusinersen before 6 months of age. Data were collected on patients who met criteria, including age at the first nusinersen dose, number of nusinersen doses, degree of scoliosis, respiratory parameters, feeding route, and motor scores at baseline and follow-up. The Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) was subanalyzed using axial (AxS) and appendicular motor (ApS) scores to evaluate a possible correlation between scoliosis and axial muscle strength.

Results

From our cohort, 31 percent (11/35) of patients had a diagnosis of SMA1. Sixty-three percent (7/11) met the inclusion criteria. All patients (7/7) showed initial improvement in their CHOP-INTEND scores in correlation with improvement on the ApS. Despite this, most patients did not show improvement in the AxS. Subsequently, all patients developed scoliosis in the first year of life with Cobb angles that ranged between 18° and 60°. Furthermore, total CHOP-INTEND scores had dropped in 2 patients alongside the development of a Cobb angle of >40°.

Discussion

Despite the significant improvement in functional motor assessment in patients with SMA1, there is a progression of significant scoliosis despite treatment. Subsequently, lack or minimal improvement on the axial CHOP-INTEND scores may predict worsening on the total motor scores.

Parents' Perspectives on Diagnosis and Decision-Making regarding Ventilator Support in Children with SMA Type 1

Spinal muscular atrophy (SMA) is a rare neuromuscular disorder with a broad clinical spectrum. The most severe phenotype-SMA type 1-is characterized by marked muscle weakness also affecting bulbar and respiratory function. Life expectancy of children with SMA type 1 is expected to be less than 2 years without ventilator support or disease-specific drug treatment. The aim of this study was to evaluate parents' perspectives on the process of decision-making regarding ventilator support in children with SMA type 1. Fourteen semi-structured interviews were performed with parents of children with SMA type 1 that decided either for or against ventilator support for their child. All children were diagnosed prior to the approval of SMA-specific drug treatment. Interviews were recorded and transcribed verbatim. Data analysis was performed using a qualitative content analysis approach according to Mayring. Parents experienced that they were not adequately informed about the disease and treatment options in first informed consent discussions. Especially regarding ventilator support, parents perceived that they were not offered ventilator support as an actual option for treatment. Regarding the decision of whether or not to offer ventilator support, parents reported that their attitude toward ventilator support and contact with other affected families or patient advocacy groups were more likely to influence the decision than the content of informed consent discussions with physicians. Our results underline the importance of an interdisciplinary team not only to provide parents with relevant information but also to consider the criteria of a patient-centered medicine.

Restoring SMN Expression: An Overview of the Therapeutic Developments for the Treatment of Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disorder and one of the most common genetic causes of infant death. It is characterized by progressive weakness of the muscles, loss of ambulation, and death from respiratory complications. SMA is caused by the homozygous deletion or mutations in the survival of the motor neuron 1 (SMN1) gene. Humans, however, have a nearly identical copy of SMN1 known as the SMN2 gene. The severity of the disease correlates inversely with the number of SMN2 copies present. SMN2 cannot completely compensate for the loss of SMN1 in SMA patients because it can produce only a fraction of functional SMN protein. SMN protein is ubiquitously expressed in the body and has a variety of roles ranging from assembling the spliceosomal machinery, autophagy, RNA metabolism, signal transduction, cellular homeostasis, DNA repair, and recombination. Motor neurons in the anterior horn of the spinal cord are extremely susceptible to the loss of SMN protein, with the reason still being unclear. Due to the ability of the SMN2 gene to produce small amounts of functional SMN, two FDA-approved treatment strategies, including an antisense oligonucleotide (AON) nusinersen and small-molecule risdiplam, target SMN2 to produce more functional SMN. On the other hand, Onasemnogene abeparvovec (brand name Zolgensma) is an FDA-approved adeno-associated vector 9-mediated gene replacement therapy that can deliver a copy of the human SMN1. In this review, we summarize the SMA etiology, the role of SMN, and discuss the challenges of the therapies that are approved for SMA treatment.

Spinal muscular atrophy: Where are we now? Current challenges and high hopes

Spinal muscular atrophy (SMA) is a neuromuscular disorder characterized by muscle weakness. It causes movement issues and severe physical disability. SMA is classified into four types based on the level of function achieved, age of onset, and maximum function achieved. The deletion or point mutation in the Survival of Motor Neuron 1 (SMN1) gene causes SMA. As a result, no full-length protein is produced. A nearly identical paralog, SMN2, provides enough stable protein to prevent death but not enough to compensate for SMN1's loss. The difference between SMN1 and SMN2 is due to different exon 7 alternative splicing patterns. SMA molecular therapies currently focus on restoring functional SMN protein by splicing modification of SMN2 exon 7 or elevated SMN protein levels. Nusinersen, an antisense oligonucleotide targeting the ISS-N1 sequence in SMN2 intron 7, was the first drug approved by the Food and Drug Administration. Risdiplam, a novel therapeutic that acts as an SMN2 exon 7 splicing modifier, was recently approved. All of these drugs result in the inclusion of SMN2 exon 7, and thus the production of functional SMN protein. Onasemnogene abeparvovec is a gene therapy that uses a recombinant adeno-associated virus that encodes the SMN protein. There are also experimental therapies available, such as reldesemtiv and apitegromab (SRK-015), which focus on improving muscle function or increasing muscle tissue growth, respectively. Although approved therapies have been shown to be effective, not all SMA patients can benefit from them due to age or weight, but primarily due to their high cost. This demonstrates the significance of continuous treatment improvement in today's medical challenges.

Respiratory outcome of spinal muscular atrophy type 1 patients treated with nusinersen

BACKGROUND

Respiratory failure is the leading cause of mortality in spinal muscular atrophy type 1 (SMA1) children. The current study aims to evaluate the effect of nusinersen treatment on respiratory outcome of the patients with SMA1.

METHODS

In this retrospective, single-center study, 52 SMA1 patients treated with nusinersen were included in the analysis. Patients were divided into two groups based on their age at the time of their first nusinersen treatment (Group 1: ≤6 months, Group 2: >6 months). Respiratory outcome on the 180th day of treatment is defined as the type of ventilation support (spontaneous breathing, noninvasive ventilation (NIV), and tracheostomized or intubated on invasive mechanical ventilation). Demographic data, respiratory outcome, and Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scores were obtained from medical records.

RESULTS

On the 180th day of treatment, 46 of the 52 (88.4%) children were alive. Prevalence of the mortality was similar in both groups (P = 0.65). The comparison of respiratory outcome in patients between group 1 and group 2 was as follows: spontaneous breathing, 7 (43.7%) versus 4 (13.3%) (P = 0.03); NIV <16 h/day, 3 (18.7%) versus 4 (13.3%) (P = 0.68); invasive mechanical ventilation, 6 (37.5%) versus 22 (73.3%) (P = 0.01). There were no patients using NIV ≥16 h/day. There were significant improvements in Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scores of the patients at day 180 in comparison with the baseline (P < 0.001).

CONCLUSIONS

Early initiation of nusinersen treatment in SMA1 patients may alter the disease's natural course.

The effects of nusinersen treatment on respiratory status of children with spinal muscular atrophy

BACKGROUND

Respiratory involvement is the main factor predicting the prognosis of spinal muscular atrophy (SMA). Significant responses in motor functions have been demonstrated with nusinersen, but pulmonary outcomes are still varied. We aimed to explore the effects of nusinersen on the respiratory functions of patients with SMA.

METHODS

Patients with SMA who were receiving regular nusinersen treatment in our tertiary care hospital were enrolled in this study. We evaluated the patients in terms of the necessity to ventilatory or nutritional support, presence of motor involvement and other comorbidities related with prognosis at three consecutive assessments.

RESULTS

The study group consisted of 43 patients (18 type 1, 12 type 2, and 13 type 3) with SMA with a mean age of 27.8 months at diagnosis and 60.8 months at the beginning of nusinersen treatment. The respiratory function improvements were noted in six patients at third assessment. Early initiation of nusinersen was significantly correlated with reduced hospital admissions (P = 0.026). Nutritional support and weight gain were remarkable in the ventilatory-supported group. Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scores were significantly higher in the non-tracheostomized group in patients with SMA type 1 (P < 0.005).

CONCLUSIONS

We posit that nusinersen may change the natural prognosis of SMA and improve care of children with SMA. Following up children with SMA for longer periods under nusinersen may be beneficial for understanding the effects of treatment. Results of our study need to be supported by future long-term studies to reach a consensus on nusinersen, considering the overall genetic and environmental status as well as the cost-effectiveness of the treatment.

Spinal muscular atrophy: from rags to riches

The aim of this paper is to provide a short history of spinal muscular atrophy, from the first descriptions of the disease to the impact of the most recent therapeutical advances on the disease course. The paper provides an overview of how the field has progressed over the years after the availability of care recommendations and, more recently of the new therapies. The paper also highlights the new challenges related to the interpretation of the efficacy of the new therapies and how these are likely to affect several aspects such as the classification of spinal muscular atrophy. We will also discuss the need for further work to better define possible new phenotypes and new methods of assessments and how these should be reflected in the care recommendations. The results in presymptomatic patients will finally highlight the need for neonatal screening.

Oral and Swallowing Abilities Tool (OrSAT) for Type 1 SMA Patients: Development of a New Module

We describe the development of a new tool specifically designed to record oral abilities, swallowing and, more generally, feeding in young type 1 SMA patients, to be used during the first 24 months of life.The tool is composed by a checklist and a separate section summarizing the functional abilities into levels of feeding/swallowing impairment. The checklist includes 12 questions assessing aspects thought to be clinically meaningful for a type 1 SMA population and developmentally appropriate for infants during the first months of life. Each item is graded with a score of 0 or 1, depending on the child's ability to perform the activity. As some items are age-dependent, the number of items to be used, and therefore the maximum score, changes with increasing age. The levels of feeding/swallowing impairment include four levels that can be identified using easily identifiable clinical criteria.In an attempt to validate the tool in an untreated population we applied it to 24 type 1 SMA patients (age range: 2.3-24.1 months, mean: 10.8) in whom the same information collected by the new tool had been previously recorded using a less-structured format.When patients were classified in three groups according to the Dubowitz decimal classification, there was a significant difference both at baseline and at follow-up (p < 0.001). The items assessing fatigue during the nursing sessions were the most frequently impaired even in infants who did not have any other obvious clinical sign of swallowing difficulties.

Estimation of the Quality-of-Life Impact of X-Linked Myotubular Myopathy

X-linked myotubular myopathy (XLMTM) is a rare, severe, neuromuscular disorder for which novel treatments are under investigation. This study estimated quality-of-life weights (or utilities) for children with XLMTM. The state that was rated the worst described a child unable to sit and requiring invasive ventilation for≥16 hours a day (utility = –0.07 or –0.27 depending on method used). The state describing a child who can stand and walk and does not require invasive ventilation was the most highly rated state and had a utility of 0.91 or 0.77 (depending on method used).

Nine health state vignettes were developed for XLMTM defined in terms of respiratory and motor function based on clinical trial data from parents completing the Assessment of Caregiver Experience with Neuromuscular Disease (ACEND) Domain 1 scale assessing mobility, transfers, sitting, playing, eating, grooming and dressing. These data were supplemented with qualitative data from parent interviews on the daily impact of XLMTM, especially in terms of psychological wellbeing, pain and discomfort, and communication. Seven clinical experts reviewed the draft vignettes for accuracy. Vignettes were rated by members of the UK general public using a time trade-off (TTO) interview and an EQ-5D-5L assessment. This study demonstrated a substantial impact of XLMTM on utility weights.

Outcomes of Long-term Non-invasive Ventilation Use in Children with Neuromuscular Disease: Systematic Review and Meta-analysis

OBJECTIVE

To determine whether children with neuromuscular disorders using long-term non-invasive ventilation, continuous or bilevel positive airway pressure, have improved health outcomes compared to alternative treatment strategies.

DATA SOURCES

This systematic review is an extension of a scoping review. The search strategy used Medical Subject Headings (MeSH) and free-text terms for "child" and "non-invasive ventilation." Studies of humans from 1990 onward were searched in MEDLINE (Ovid), Embase (Ovid), CINAHL (Ebsco), Cochrane Library (Wiley), and PubMed. The results were reviewed for articles reporting on neuromuscular disorders and health outcomes including mortality, hospitalization, quality of life, lung function, sleep study parameters, and healthcare costs.

DATA EXTRACTION

Extracted data included study design, study duration, sample size, age, type of non-invasive ventilation, follow-up period, primary disease, and primary and secondary outcome measures. Studies were grouped by primary disease into 3 groups: spinal muscular atrophy, Duchenne muscular dystrophy, and other/multiple neuromuscular diseases.

DATA SYNTHESIS

A total of 50 articles including 1412 children across 36 different neuromuscular disorders are included in the review. Mortality is lower for children using long-term non-invasive ventilation compared to supportive care across all neuromuscular disease types. Overall, mortality does not differ when comparing the use of non-invasive ventilation to invasive mechanical ventilation though heterogeneity suggests that mortality with non-invasive ventilation is higher for spinal muscular atropy type-1 and lower for other/multiple neuromuscular diseases. The impact of long-term non-invasive ventilation on hospitalization rate differed by neuromuscular disease type with lower rates compared to invasive mechanical ventilation but higher rates compared to invasive mechanical ventilation use for spinal muscular atrophy type 1, and lower rates compared to before NIV for other/multiple neuromuscular diseases. Overall, lung function was unaltered and sleep study parameters were improved from baseline by long-term non-invasive ventilation use. There are few data to assess the impact of long-term non-invasive ventilation use on quality of life and healthcare costs.

CONCLUSION

Long-term non-invasive ventilation for children provides benefit for mortality, hospitalizations, and sleep study parameters for some sub-groups of children with neuromuscular disorders. High risk of bias and low study quality preclude strong conclusions.

Restoring Protein Expression in Neuromuscular Conditions: A Review Assessing the Current State of Exon Skipping/Inclusion and Gene Therapies for Duchenne Muscular Dystrophy and Spinal Muscular Atrophy

The debilitating neuromuscular disorders Duchenne muscular dystrophy (DMD) and spinal muscular atrophy (SMA), which harm 1 in 5000 newborn males and 1 in 11,000 newborns, respectively, are marked by progressive muscle wasting among other complications. While DMD causes generalized muscle weakness due to the absence of the dystrophin protein, SMA patients generally face motor neuron degeneration because of the lack of the survival motor neuron (SMN) protein. Many of the most promising therapies for both conditions restore the absent proteins dystrophin and SMN. Antisense oligonucleotide-mediated exon skipping and inclusion therapies are advancing clinically with the approved DMD therapies casimersen, eteplirsen, golodirsen, and viltolarsen, and the SMA therapy nusinersen. Existing antisense therapies focus on skeletal muscle for DMD and motor neurons for SMA, respectively. Through innovative techniques, such as peptide conjugation and multi-exon skipping, these therapies could be optimized for efficacy and applicability. By contrast, gene replacement therapy is administered only once to patients during treatment. Currently, only onasemnogene abeparvovec for SMA has been approved. Safety shortcomings remain a major challenge for gene therapy. Nevertheless, gene therapy for DMD has strong potential to restore dystrophin expression in patients. In light of promising functional improvements, antisense and gene therapies stand poised to elevate the lives of patients with DMD and SMA.

Effect of nusinersen on respiratory function in paediatric spinal muscular atrophy types 1-3

INTRODUCTION

Nusinersen is used in spinal muscular atrophy (SMA) to improve peripheral muscle function; however, respiratory effects are largely unknown.

AIM

To assess the effects of nusinersen on respiratory function in paediatric SMA during first year of treatment.

METHODS

A prospective observational study in paediatric patients with SMA who began receiving nusinersen in Queensland, Australia, from June 2018 to December 2019. Outcomes assessed were the age-appropriate respiratory investigations: spirometry, oscillometry, sniff nasal inspiratory pressure, mean inspiratory pressure, mean expiratory pressure, lung clearance index, as well as polysomnography (PSG) and muscle function testing. Lung function was collected retrospectively for up to 2 years prior to nusinersen initiation. Change in lung function was assessed using mixed effects linear regression models, while PSG and muscle function were compared using the Wilcoxon signed-rank test.

RESULTS

Twenty-eight patients (15 male, aged 0.08-18.58 years) were enrolled: type 1 (n=7); type 2 (n=12); type 3 (n=9). The annual rate of decline in FVC z-score prior to nusinersen initiation was -0.58 (95% CI -0.75 to -0.41), and post initiation was -0.25 (95% CI -0.46 to -0.03), with a significant difference in rate of decline (0.33 (95% CI 0.02 to 0.66) (p=0.04)). Most lung function measures were largely unchanged in the year post nusinersen initiation. The total Apnoea-Hypopnoea Index (AHI) was reduced from a median of 5.5 events/hour (IQR 2.1-10.1) at initiation to 2.7 events/hour (IQR 0.7-5.3) after 1 year (p=0.02). All SMA type 1% and 75% of SMA types 2 and 3 had pre-defined peripheral muscle response to nusinersen.

CONCLUSION

The first year of nusinersen treatment saw reduced lung function decline (especially in type 2) and improvement in AHI.

Revisiting the role of mitochondria in spinal muscular atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disease of variable clinical severity that is caused by mutations in the survival motor neuron 1 (SMN1) gene. Despite its name, SMN is a ubiquitous protein that functions within and outside the nervous system and has multiple cellular roles in transcription, translation, and proteostatic mechanisms. Encouragingly, several SMN-directed therapies have recently reached the clinic, albeit this has highlighted the increasing need to develop combinatorial therapies for SMA to achieve full clinical efficacy. As a subcellular site of dysfunction in SMA, mitochondria represents a relevant target for a combinatorial therapy. Accordingly, we will discuss our current understanding of mitochondrial dysfunction in SMA, highlighting mitochondrial-based pathways that offer further mechanistic insights into the involvement of mitochondria in SMA. This may ultimately facilitate translational development of targeted mitochondrial therapies for SMA. Due to clinical and mechanistic overlaps, such strategies may also benefit other motor neuron diseases and related neurodegenerative disorders.

Sleep disordered breathing: Assessment and therapy in the age of emerging neuromuscular therapies

The term neuromuscular disease (NMD) encompasses a large variety of disorders that result in abnormal muscle function. Although it may be conventional to relate the use of this term to the most common muscular diseases (Duchenne muscular dystrophy [DMD], spinal muscular atrophy [SMA], and amyotrophic lateral sclerosis, etc), it is important to extend the term to pathologies manifested by severe neurologic (brain and spinal cord) malformations and injuries. In many of these scenarios, there are common mechanisms that contribute to sleep disordered breathing (SDB) and respiratory insufficiency although comorbidities may be somewhat different. Advances in the understanding of these diseases and their natural history, and increasing availability of mechanical ventilation to these patients have improved survival. The development of novel genetic and molecular therapies (as in the cases of DMD, SMA, and X-linked myotubular myopathy) provides an opportunity to use SDB as a reasonable outcome measure while also allowing the use of polysomnography as a validation tool in the assessments of effectiveness of therapies. We seek to provide an understanding of SDB in NMDs, and in the same light, would like to begin the conversation of thinking about weaning respiratory support when possible.

A new respiratory scoring system for evaluation of respiratory outcomes in children with spinal muscular atrophy type1 (SMA1) on SMN enhancing drugs

Nusinersen (NUS), the first treatment approved for Spinal Muscular Atrophy type 1 (SMA1), was made available in the UK for SMA1 through the Expanded Access Program (EAP) in 2017. The Great Ormond Street Respiratory (GSR) score was developed as an objective respiratory assessment for children with SMA1 during their treatment. Aims: Track respiratory status of SMA1 children over the course of Nusinersen treatment and compare GSR scores amongst SMA1 sub-types. Single centre study on SMA1 patients using the GSR score at set time points: prior to first NUS dose; 2 weeks post end of loading doses; 2 weeks post-subsequent doses. GSR score ranges 1-28, being 1-9 = Stable minimal support, thorough to 23-28 = Poor reserve with maximum support. 20 SMA1 children underwent NUS treatment between January 2017 - November 2018. Median age of diagnosis was 5.0 months. NUS started at median of 9.57 months. From 5th dose onwards, GSR scores were significantly lower for Type 1C patients compared to Type 1B By month 18, irrespective of subtypes, the whole cohort appears to stabilise GSR Scores. As treatment duration increases, an overall stabilisation of respiratory status across the cohort was observed. Further longitudinal studies are needed to validate the GSR.

Clinical Experience of Nusinersen in a Broad Spectrum of Spinal Muscular Atrophy: A Retrospective Study

Background:

Nusinersen has recently been approved and more widely used as first-line treatment of spinal muscular atrophy (SMA). This study aimed to evaluate the real-world experience of nusinersen use for patients with a broad spectrum of SMA.

Methods:

We reviewed consecutive patients with SMA treated with nusinersen from April 2018 to April 2020. Data collected included clinical and diagnostic characteristics, molecular genetics, functional motor outcomes, and adverse events.

Results:

Seven patients including four with SMA type 1 and three with SMA type 2 were treated with nusinersen. The median disease duration at the time of the first dose and the median follow-up duration were 37 months (range: 0.5–254 months) and 6.1 months (range: 2.1–22.1 months), respectively. Of the 41 lumbar punctures (LPs), seven fluoroscopy-guided LPs were successfully performed for two patients without sedation. All patients showed improvement in motor function even though the current tools for motor assessment seemed unable to detect subtle subjective improvement. All patients maintained a stable respiratory status. No patient has experienced a severe adverse event or discontinued treatment so far.

Conclusion:

Although the number of patients in this study was small, our results suggest that nusinersen is effective even in patients with a later stage of the disease. Additional long-term prospective studies with more number of patients having a broad spectrum of diseases are needed to identify meaningful improvement in the motor function and quality of life after nusinersen treatment.

Persistent Pseudomonas aeruginosa infection associated with non-invasive ventilation in a child with spinal muscular atrophy type 1

NONE

Current standards of care suggest the use of non-invasive positive pressure ventilation (NIV) in children with spinal muscular atrophy and symptomatic respiratory failure. Theoretical concerns exist regarding NIV equipment as a source of infection in restrictive lung disease due to the possibility of prolonged NIV device use, greater risk in acquiring infections, and difficulties in managing and clearing infections. NIV devices may draw pathogens through the air inlet port that may contaminate the internal surfaces. These pathogens may then infect children with spinal muscular atrophy. We present a case of 2 genetically identical Pseudomonas aeruginosa cultures from both the patient's NIV device and from nasopharyngeal samples. This infection persisted both in nasopharyngeal aspirate cultures and from NIV equipment cultures despite the use of an eradication program involving both the child and the NIV device.

Successful weaning from mechanical ventilation in a patient with SMA type 1 treated with nusinersen

SMA type 1 is the most severe type, characterized by early onset at <6 months of age, and rapid progression resulting in permanent assisted ventilation before 2 years of life. Supportive care was the only treatment until the approval of nusinersen, an antisense oligonucleotide drug that increases functional SMN protein levels. We present a case of successful weaning from permanent ventilation via tracheostomy with nusinersen in an infant who had been diagnosed with SMA type 1 at the age of one month and had become ventilator‐dependent from the age of 3 months.

Clinical Outcomes in Patients with Spinal Muscular Atrophy Type 1 Treated with Nusinersen

BackgroundSpinal muscular atrophy type 1 (SMA1) is a motor neuron disease associated with progressive muscle weakness, ventilatory failure, and reduced survival.Objective:To report the evaluation of the nusinersen, an antisense oligonucleotide, on the motor function of SMA1.MethodsThis was a longitudinal and observational study to assess the outcomes of nusinersen therapy in SMA1 patients using the HINE-2 and CHOP-INTEND scales.ResultsTwenty-one SMA1 patients (52.4% males) were included; the mean age at first symptoms was 2.7 months (SD =±1.5), and the mean disease duration at first dose was 34.1 (SD =±36.0) months. During posttreatment, the mean gain on the CHOP-INTEND was 4.9, 5.9, 6.6, and 14 points after 6, 12, 18, and 24 months, respectively. Starting medication with a disease duration of less than 12 months and/or without invasive ventilation were predictors of response on CHOP-INTEND. Of the patients, 28.6% acquired a motor milestone or gained at least three points on the HINE-2. The daily time for ventilatory support was reduced after treatment in most of the patients with noninvasive ventilation at baseline. No change in the daytime use of ventilation was observed in most of the patients using invasive ventilation at baseline.ConclusionsNusinersen produces improvements in motor and respiratory functions, even in long-term SMA1 patients. However, patients under invasive ventilation at the beginning of the treatment experience little benefit.

Nusinersen: A Review in 5q Spinal Muscular Atrophy

Survival motor neuron 1 (SMN1), located on chromosome 5q, encodes the survival motor neuron (SMN) protein. A deletion or mutation in SMN1 results in a rare neuromuscular disorder: 5q spinal muscular atrophy (SMA). In such patients, SMN protein production relies solely on SMN2. Nusinersen (Spinraza^®) is a modified antisense oligonucleotide approved for the treatment of 5q SMA. Administered intrathecally, it modifies SMN2 pre-messenger RNA splicing, thereby increasing full-length SMN protein levels. Interim analyses from an ongoing phase II study suggest substantial clinical benefits with nusinersen initiation in presymptomatic patients. In phase III studies, nusinersen achieved significant and/or clinically relevant improvements in motor function in symptomatic patients with infantile- and later-onset 5q SMA, and significantly improved event-free survival and overall survival in patients with infantile-onset 5q SMA. Longer term (up to a median of ≈ 6 years of available data), motor function was maintained or improved in symptomatic patients. Nusinersen had a favourable safety profile in clinical studies in presymptomatic and symptomatic patients. Real-world experience supports the effectiveness, safety and tolerability of nusinersen in symptomatic patients of all ages. Thus, nusinersen remains an important treatment option among a broad range of 5q SMA patients.

All You Need Is Evidence: What We Know About Pneumonia in Children With Neuromuscular Diseases

Neuromuscular diseases may involve all major respiratory muscles groups including inspiratory, expiratory, and bulbar muscles. Respiratory complications are the major cause of morbidity and mortality. Pneumonia represents a frequent cause of morbidity in children with neuromuscular disease. The aim of this review is to collect knowledge about pneumonia in children with neuromuscular diseases. Pneumonia usually follows viral respiratory infections of the upper respiratory tract, due to the combination of an increased amount of nasal and oral secretions and an impairment of the cough efficiency and of the clearance of secretions due to the muscle weakness, further compromised by the infection itself. The accumulation of bronchial secretions leads to atelectasis and promote bacterial infection. Moreover, dysfunction of swallowing mechanism exposes these children to the risk of developing aspiration pneumonia. However, etiology of viral and bacterial respiratory infection in these patients is still poorly studied.

Spinal muscular atrophy - insights and challenges in the treatment era

Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disease caused by deletion or mutation of SMN1. Four subtypes exist, characterized by different clinical severities. New therapeutic approaches have become available in the past few years, dramatically changing the natural history of all SMA subtypes, including substantial clinical improvement with the severe and advanced SMA type 1 variant. Trials have now demonstrated that phenotypic rescue is even more dramatic when pre-symptomatic patients are treated, and emerging real-world data are demonstrating the benefits of intervention even in the chronic phase of the condition. Here, we critically review how the field is rapidly evolving in response to the new therapies and questions that the new treatments have posed, including the effects of treatment at different ages and stages of disease, new phenotypes and long-term outcomes in patients who would not have survived without treatment, and decisions of who to treat and when. We also discuss how the outcomes associated with different timing of therapeutic intervention are contributing to our understanding of the biology and pathogenesis of SMA.

New and Developing Therapies in Spinal Muscular Atrophy: From Genotype to Phenotype to Treatment and Where Do We Stand?

Spinal muscular atrophy (SMA) is a congenital neuromuscular disorder characterized by motor neuron loss, resulting in progressive weakness. SMA is notable in the health care community because it accounts for the most common cause of infant death resulting from a genetic defect. SMA is caused by low levels of the survival motor neuron protein (SMN) resulting from SMN1 gene mutations or deletions. However, patients always harbor various copies of SMN2, an almost identical but functionally deficient copy of the gene. A genotype–phenotype correlation suggests that SMN2 is a potent disease modifier for SMA, which also represents the primary target for potential therapies. Increasing comprehension of SMA pathophysiology, including the characterization of SMN1 and SMN2 genes and SMN protein functions, has led to the development of multiple therapeutic approaches. Until the end of 2016, no cure was available for SMA, and management consisted of supportive measures. Two breakthrough SMN-targeted treatments, either using antisense oligonucleotides (ASOs) or virus-mediated gene therapy, have recently been approved. These two novel therapeutics have a common objective: to increase the production of SMN protein in MNs and thereby improve motor function and survival. However, neither therapy currently provides a complete cure. Treating patients with SMA brings new responsibilities and unique dilemmas. As SMA is such a devastating disease, it is reasonable to assume that a unique therapeutic solution may not be sufficient. Current approaches under clinical investigation differ in administration routes, frequency of dosing, intrathecal versus systemic delivery, and mechanisms of action. Besides, emerging clinical trials evaluating the efficacy of either SMN-dependent or SMN-independent approaches are ongoing. This review aims to address the different knowledge gaps between genotype, phenotypes, and potential therapeutics.