Spinal muscular atrophy

Healthcare Utilization, Costs of Care, and Mortality Among Psatients With Spinal Muscular Atrophy

OBJECTIVES

To understand treatment patterns, healthcare resource utilization, and costs of care among patients with spinal muscular atrophy (SMA). Methods: SMA patients were identified from a large managed care population using administrative claims data from January 2006 to March 2016. Patients were classified into infantile, childhood-onset, and late-onset groups based on age of first SMA diagnosis. They were matched 1:1 to non-SMA patients based on age, gender, geography, and health plan type.

RESULTS

In the infantile group, 17.4% and 26.1% were treated with invasive and non-invasive ventilation, respectively. Uses of orthotics/orthoses and orthopedic surgery were frequent: 54.5% and 22.7% childhood group; 27.0% and 38.5% late-onset group. Mean per member per month costs in SMA vs. matched non-SMA patients was $25,517 vs. $406 (infantile); $6,357 vs. $188 (childhood-onset); $2,499 vs. $742 (late-onset).

CONCLUSIONS

SMA patients, particularly with infantile onset, incurred significantly higher healthcare utilization and costs than the general population.

Identification of Novel Microsatellite Markers Flanking the SMN1 and SMN2 Duplicated Region and Inclusion Into a Single-Tube Tridecaplex Panel for Haplotype-Based Preimplantation Genetic Testing of Spinal Muscular Atrophy

Preimplantation genetic testing for the monogenic disorder (PGT-M) spinal muscular atrophy (SMA) is significantly improved by supplementation of SMN1 deletion detection with marker-based linkage analysis. To expand the availability of informative markers for PGT-M of SMA, we identified novel non-duplicated and highly polymorphic microsatellite markers closely flanking the SMN1 and SMN2 duplicated region. Six of the novel markers within 0.5 Mb of the 1.7 Mb duplicated region containing SMN1 and SMN2 (SMA6863, SMA6873, SMA6877, SMA7093, SMA7115, and SMA7120) and seven established markers (D5S1417, D5S1413, D5S1370, D5S1408, D5S610, D5S1999, and D5S637), all with predicted high heterozygosity values, were selected and optimized in a tridecaplex PCR panel, and their polymorphism indices were determined in two populations. Observed marker heterozygosities in the Chinese and Caucasian populations ranged from 0.54 to 0.86, and 98.4% of genotyped individuals (185 of 188) were heterozygous for ≥2 markers on either side of SMN1. The marker panel was evaluated for disease haplotype phasing using single cells from two parent–child trios after whole-genome amplification, and applied to a clinical IVF (in vitro fertilization) PGT-M cycle in an at-risk couple, in parallel with SMN1 deletion detection. Both direct and indirect test methods determined that none of five tested embryos were at risk for SMA, with haplotype analysis further identifying one embryo as unaffected and four as carriers. Fresh transfer of the unaffected embryo did not lead to implantation, but subsequent frozen-thaw transfer of a carrier embryo produced a pregnancy, with fetal genotype confirmed by amniocentesis, and a live birth at term.

Estimation Of The Quality Of Life Benefits Associated With Treatment For Spinal Muscular Atrophy

Background

Spinal muscular atrophy (SMA) is a rare, genetic, progressive neuromuscular disorder characterized by severe muscle atrophy and weakness and is a leading genetic cause of death in infants and children. Nusinersen was the first treatment targeting the underlying cause of disease approved by the FDA, EMA and other countries for patients with SMA. There are currently very limited data available on the health-related quality of life (HRQoL) burden of SMA suitable for use in a cost-effectiveness analysis.

Objective

This study was designed to estimate quality of life weights or utilities for different SMA states.

Methods

SMA case studies were developed describing Type I (infantile onset) and Type II (later-onset) patients and different outcomes from treatment. These were developed so that quality of life weights or utilities (where the value of health ranges from 1 – full health to 0 – dead) could be estimated for cost-effectiveness analysis. Clinical experts (n=5) rated each of the case studies using standardized HRQoL instruments – the EQ-5D-Y and PedsQL-NMM (baseline states only).

Results

The SMA Type I utilities ranged from −0.33 (requires ventilation) to 0.71 (Type I patient reclassified as Type III following treatment), with quite substantial differences between some states. Most Type I states had a utility score below zero indicating the severity of the states. The SMA Type II utilities ranged from −0.13 (worsened) to 0.72 (stands/walks unaided). In general, the results showed HRQoL improved in line with better health states.

Conclusion

The utility scores obtained in this study highlight the very substantial burden experienced by SMA patients. Despite the limitations in the methods used, this study produced data with face validity and is a useful starting point for understanding the burden of SMA Types I and II in cost-effectiveness analysis.

[Treatment evaluation in patients with 5q-associated spinal muscular atrophy : Real-world experience]

Spinal muscular atrophy (SMA) is a progressive autosomal recessive neurodegenerative disease with an incidence of 1:10,000 live births. With a deeper understanding of the molecular basis of SMA in the past two decades, a major focus of therapeutic development has been on increasing the proportion of functionally capable SMN protein by increasing the inclusion of exon 7 in SMN2 transcripts, enhancing SMN2 gene expression, stabilizing the SMN protein or replacing the SMN1 gene. Since June 2017, the antisense oligonucleotide nusinersen/Spinraza® (Biogen GmbH, Ismaning, Germany) has been approved for 5qSMA treatment. Nusinersen modifies premessenger RNA splicing of exon 7, leading to stable SMN protein expression and for the first time an effective disease-modifying treatment is available. In several controlled trials nusinersen showed a favorable benefit-risk profile along with clinically relevant improvements in motor function. The efficacy was most pronounced in presymptomatic patients, which underlines the necessity for a newborn screening program and is the key to start efficient treatment prior to motor neuron death. The repeated intrathecal administration of nusinersen is associated with practical challenges, in particular for patients with severe scoliosis or after spinal straightening surgery. As the vast majority of SMA patients were outside previous study populations regarding age and disease duration, experts complained about a lack of data on efficacy and safety beyond childhood. To fill these gaps a systematic data collection has been initiated by the SMArtCARE initiative, aiming at collecting comprehensive data in the clinical routine, regardless of the patients' individual treatment regimen.

Long-term progression in type II spinal muscular atrophy: A retrospective observational study

OBJECTIVE

To report the long-term progression in a cohort of patients with type II spinal muscular atrophy (SMA) assessed with the Hammersmith Functional Motor Scale-Expanded.

METHODS

Seventy-three patients (age 2.6-25 years) were included in the study. Twenty-eight of the 73 were first assessed before the age of 5 years and had been followed up for ≈5 years or longer. We observed an overall progression that was not linear. A piecewise regression analysis showed an improvement of scores in the younger patients with a point of slope change at ≈5 years of age, a decline between 5 and 13 years of age, and stability/slower decline after that.

RESULTS

Patients with the lowest scores at baseline had the earliest onset of scoliosis and a higher need for noninvasive ventilation compared to those with higher scores. Our results confirm that on the long-term follow-up all patients with type II SMA show a clear and progressive decline.

CONCLUSION

The severity of functional impairment at baseline can help to predict the magnitude of changes over time and the overall progression, including onset of scoliosis and need for noninvasive ventilation.

Intrathecal administration of nusinersen in adult and adolescent patients with spinal muscular atrophy and scoliosis: Transforaminal versus conventional approach

Spinal deformities and surgical correction of scoliosis can make intrathecal delivery of nusinersen very challenging. We aim to evaluate the feasibility and safety of intrathecal administration of nusinersen either via interlaminar or transforaminal approach in a cohort of adult and adolescent patients with spinal muscular atrophy (SMA). Twelve patients were treated with nusinersen in our center under CT-guidance; after a CT scan of the lumbar column, we identified a safe virtual trajectory for the needle and defined patients to address to the transforaminal approach (seven patients) or the interlaminar approach (five patients). Out of 47 procedures, all injections but one were successful. There was one adverse event (post-lumbar puncture syndrome) in the interlaminar approach group (out of 20 procedures) and four adverse events in TFA group (out of 27 procedures) including one serious adverse event, a subarachnoid hemorrhage that required hospitalization. Transforaminal approach can be considered an effective option for nusinersen administration but potentially associated with serious complications, therefore it should be recommended in very selected patients.

Neurotheranostics as personalized medicines

The discipline of neurotheranostics was forged to improve diagnostic and therapeutic clinical outcomes for neurological disorders. Research was facilitated, in largest measure, by the creation of pharmacologically effective multimodal pharmaceutical formulations. Deployment of neurotheranostic agents could revolutionize staging and improve nervous system disease therapeutic outcomes. However, obstacles in formulation design, drug loading and payload delivery still remain. These will certainly be aided by multidisciplinary basic research and clinical teams with pharmacology, nanotechnology, neuroscience and pharmaceutic expertise. When successful the end results will provide "optimal" therapeutic delivery platforms. The current report reviews an extensive body of knowledge of the natural history, epidemiology, pathogenesis and therapeutics of neurologic disease with an eye on how, when and under what circumstances neurotheranostics will soon be used as personalized medicines for a broad range of neurodegenerative, neuroinflammatory and neuroinfectious diseases.

Observations from a nationwide vigilance program in medical care for spinal muscular atrophy patients in Chile

METHODS

Spinal muscular atrophy (SMA) has gained much attention in the last few years because of the approval of the first intrathecal treatment for this neurodegenerative disease. Latin America needs to develop the demographics of SMA, timely access to diagnosis, and appropriate following of the standards of care recommendations for patients. These are essential steps to guide health policies. This was a descriptive study of a cohort of SMA patients from all over Chile. We analyzed the clinical, motor functional, and social data, as well as the care status of nutritional, respiratory and skeletal conditions. We also measured the SMN2 copy number in this population.

RESULTS

We recruited 92 patients: 50 male; 23 SMA type-1, 36 SMA type-2 and 33 SMA type-3. The median age at genetic diagnosis was 5, 24 and 132 months. We evaluated the SMN2 copy number in 57 patients. The SMA type-1 patients were tracheostomized and fed by gastrostomy in a 69.6 % of cases, 65% of SMA type-2 patients received nocturnal noninvasive ventilation, and 37% of the whole cohort underwent scoliosis surgery.

CONCLUSION

Ventilatory care for SMA type-1 is still based mainly on tracheostomy. This Chilean cohort of SMA patients had timely access to genetic diagnosis, ventilatory assistance, nutritional support, and scoliosis surgery. In this series, SMA type-1 is underrepresented, probably due to restrictions in access to early diagnosis and the high and early mortality rate.

Nusinersen improves walking distance and reduces fatigue in later-onset spinal muscular atrophy

Introduction

Ambulatory individuals with spinal muscular atrophy (SMA) experience muscle weakness, gait impairments, and fatigue that affect their walking ability. Improvements have been observed in motor function in children treated with nusinersen, but its impact on fatigue has not been studied.

Methods

Post hoc analyses were used to examine changes in 6‐minute walk test (6MWT) distance and fatigue in children and adolescents with SMA type II and III who received their first dose of nusinersen in the phase Ib/IIa, open‐label CS2 study and were ambulatory during CS2 or the extension study, CS12.

Results

Fourteen children performed the 6MWT. Median (25th, 75th percentile) distance walked increased over time by 98.0 (62.0, 135.0) meters at day 1050, whereas median fatigue changed by −3.8% (−19.7%, 1.4%).

Discussion

These results support previous studies demonstrating clinically meaningful effects of nusinersen on motor function in children and adolescents with later‐onset SMA.

Challenges of gene delivery to the central nervous system and the growing use of biomaterial vectors

Gene therapy is a promising form of treatment for those suffering from neurological disorders or central nervous system (CNS) injury, however, obstacles remain that limit its translational potential. The CNS is protected by the blood brain barrier, and this barrier blocks genes from traversing into the CNS if administered outside of the CNS. Viral and non-viral gene delivery vehicles, commonly referred to as vectors, are modified to enhance delivery efficiency to target locations in the CNS. Still, there are few gene therapy approaches approved by the FDA for CNS disease or injury treatment. The lack of viable clinical approaches is due, in part, to the unpredictable nature of many vector systems. In particular, safety concerns exist with the use of viral vectors for CNS gene delivery. To seek some alternatives to viral vectors, development of new non-viral, biomaterial vectors is occurring at a rapid rate. This review discusses the challenges of delivering various forms of genetic material to the CNS, the use and limitations of current viral vector delivery systems, and the use of non-viral, biomaterial vectors for CNS applications.

Spinal Muscular Atrophy and Common Therapeutic Advances

BACKGROUND

Spinal muscular atrophy (SMA) is an autosomal recessive destructive motor neuron disease which is characterized primarily by the degeneration of α-motor neurons in the ventral gray horn of the spinal cord. It mainly affects children and represents the most common reason of inherited infant mortality.

MATERIAL AND METHODS

We provide an overview of the recent therapeutic strategies for the treatment of SMA together with available and developing therapeutic strategies. For this purpose, Google Scholar and PubMed databases were searched for literature on SMA, therapy and treatment. Titles were reviewed and 96 were selected and assessed in this paper.

RESULT

Over the last two decades, different therapeutic strategies have been proposed for SMA. Some methods are in the pre-clinical, others the clinical phase.

CONCLUSION

By emergence of the new approaches, especially in gene therapy, effective treatment in the close future is probable.

The effect of two different aerobic training modalities in a child with spinal muscular atrophy type II: a case report

This study examined the effect of two different aerobic training modalities in a boy with spinal muscular atrophy type II. Motor functions were measured with Hammersmith Functional Motor Scale (HFMS) and Gross Motor Function Measure (GMFM). Spirometry was utilized for assessing pulmonary functions and PedsQL 3.0 Neuromuscular module was utilized for quality of life of child. Ergometer training was applied 3 times per week for the duration of 12 weeks. After 6 weeks of wash-out period, aquatherapy was applied for twice a week for the duration of 12 weeks. HFMS and GMFM scores, and pulmonary functions of the child and quality of life scores of his parents were improved during both modalities. These improvements were largely maintained during 1-year follow-up. This study showed that both modalities had similar effects on our case’s pulmonary, motor functions and quality life of himself and parents. It will be a guide for researchers working in the area of children with neuromuscular disorders regarding plan and diversification of therapy program.

Isoform-selective as opposed to complete depletion of fibroblast growth factor 2 (FGF-2) has no major impact on survival and gene expression in SOD1G93A amyotrophic lateral sclerosis mice

We have previously shown that total knockout of fibroblast growth factor-2 (FGF-2) results in prolonged survival and improved motor performance in superoxide dismutase 1 (SOD1^G93A ) mutant mice, the most widely used animal model of the fatal adult onset motor neuron disease amyotrophic lateral sclerosis (ALS). Moreover, we found differential expression of growth factors in SOD1^G93A mice, with distinct regulation patterns of FGF-2 in spinal cord and muscle tissue. Within the present study we aimed to characterize FGF-2-isoform specific effects on survival, motor performance as well as gene expression patterns predominantly in muscle tissue by generating double mutant SOD1^G93A FGF-2 high molecular weight- and SOD1^G93A FGF-2 low molecular weight-knockout mice. While isoform specific depletion was not beneficial regarding survival or motor performance of double mutant mice, we found isoform-dependent differential gene expression of epidermal growth factor (EGF) in the muscle of SOD1^G93A FGF-2 low molecular weight knockout mice compared to single mutant SOD1^G93A mice. This significant downregulation of EGF in the muscle tissue of double mutant SOD1^G93A FGF-2 low molecular weight knockout mice implies that FGF-2 low molecular weight knockout (or the presence of the FGF-2 high molecular weight isoform) selectively impacts EGF gene expression in ALS muscle tissue.

Survival, Motor Function, and Motor Milestones: Comparison of AVXS-101 Relative to Nusinersen for the Treatment of Infants with Spinal Muscular Atrophy Type 1

Introduction

Infants with spinal muscular atrophy (SMA) type 1 typically face a decline in motor function and a severely shortened life expectancy. Clinical trials for SMA type 1 therapies, onasemnogene abeparvovec (AVXS-101) and nusinersen, demonstrated meaningful improvements in efficacy (e.g., overall survival) but there were no head-to-head clinical trials assessing comparative efficacy. This study estimated the treatment effects of AVXS-101 relative to nusinersen for the treatment of SMA type 1.

Methods

Overall survival, event-free survival (no death or need to use permanent assisted ventilation), improvement in motor function [increase of ≥ 4 points in Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) score from baseline], and motor milestone achievements (head control, rolling over, and sitting unassisted) reported in the onasemnogene abeparvovec (AVXS-101-CL-101; NCT02122952) and nusinersen (ENDEAR; NCT02193074) clinical trials were indirectly compared using frequentist and Bayesian approaches.

Results

Among symptomatic infants with SMA type 1, the number needed to treat (NNT) to prevent one more death with AVXS-101 instead of nusinersen was 6.2 [95% confidence intervals (CI) = 4.1–12.2], and the probability of preventing death was 20% higher for patients treated with AVXS-101 than nusinersen [risk ratio (RR) = 1.2, 95% CI 1.1–1.3]. For event-free survival, the NNT to prevent one more event was 2.6 (95% CI 2.0–3.6) and RR was 1.6 (95% CI 1.4–1.9). For improvement in motor function, NNT was 3.5 (95% CI 2.6–5.3) and RR was 1.4 (95% CI 1.2–1.6). For milestone achievements, the NNTs were 1.4 (95% CI 1.1–1.9), 1.5 (95% CI 1.1–2.5), and 1.2 (95% CI 1.0–1.5); RRs 4.2 (95% CI 2.6–6.7), 7.8 (95% CI 3.6–17.0), and 11.2 (95% CI 5.1–24.5) for head control, rolling over, and sitting unassisted, respectively. Results were similar using the Bayesian approach.

Conclusion

This indirect comparison (AVXS-101-CL-101 vs. ENDEAR) among symptomatic SMA type 1 infants suggests that AVXS-101 may have an efficacy advantage relative to nusinersen for overall survival, independence from permanent assisted ventilation, motor function, and motor milestones.

Funding

AveXis.

Reliability of four tests to assess body posture and the range of selected movements in individuals with spinal muscular atrophy

Background

The majority of individuals with spinal muscular atrophy (SMA) experience progressive skeletal deformities which may affect the quality of life and mobility. To date, no studies have evaluated the reliability of tests assessing body posture and joint mobility in SMA patients. The purpose of this study was to assess the reliability of Cervical Rotation test (CR), Supine Angle of Trunk Rotation test (SATR), Hip Extension test (HE) and Pelvic Obliquity test (PO) developed to evaluate the musculoskeletal system in SMA individuals.

Methods

Thirty individuals (12 girls and 18 boys) aged 4–15 with SMA type II (n = 24) and III (n = 6) confirmed by genetic examinations were qualified for the study. The participants were examined twice by three physiotherapists on the same day. The examination included four tests, i.e. CR, SATR, HE and PO tests aimed at assessing ranges of rotation in the cervical spine, chest deformities, ranges of hip extension and pelvis position while sitting. Statistical calculations were made with the use of statistical software IBM SPSS Statistics version 20. Reliability was assessed using the Intraclass Correlation Coefficient (ICC).

Results

Intraobserver reliability was excellent for CR (ICC range 0.839–0.911), SATR (ICC range 0.918–0.939 - the upper part of the sternum; ICC range 0.951–0.975 - the lower part of the sternum), HE (ICC range 0.988–0,991) and PO (ICC range 0.896–0.935) tests.

The interobserver ICC reached the excellent values in CR (ICC range 0.912–0.920), SATR (ICC = 0.888 - the upper part of the sternum, ICC = 0.951 - the lower part of the sternum), HE (ICC range 0.922–0.923) and PO (ICC = 0.928) tests.

Conclusions

CR, SATR, HE and PO tests are reliable and may be used for examining individuals with SMA. The application of these tests provides a possibility to detect early changes in the musculoskeletal system in children and adolescents and to assess the effectiveness of the implemented pharmacotherapy and rehabilitation.

Incidence of infantile spinal muscular atrophy on Shikoku Island of Japan

BACKGROUND

Spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by homozygous mutations in the SMN1 gene. SMA has long been known to be the most common genetic cause of infant mortality. However, there have been no reports on the epidemiology of infantile SMA (types 1 and 2) based on genetic testing in Japan. In this study, we estimated the incidence of infantile SMA on Shikoku Island, which is a main island of Japan and consists of four prefectures: Ehime, Kagawa, Tokushima and Kochi.

METHODS

A questionnaire was sent to 91 hospitals on Shikoku Island to investigate the number of SMA infants born from 2011 to 2015. A second questionnaire was then sent to confirm the diagnoses of SMA based on clinical and genetic features.

RESULTS

Responses were received from all of the hospitals, and four patients were diagnosed with infantile SMA among 147,950 live births. We estimated the incidence of infantile SMA patients as 2.7 per 100,000 live births (95% confidence interval, 0.1-5.4). A comparison of the four prefectures indicated that the incidence of infantile SMA was significantly higher in Ehime Prefecture than in the other three prefectures; 5.6 per 100,000 live births (95% confidence interval, -0.7 to 11.9) in Ehime Prefecture and 1.1 per 100,000 live births (95% confidence interval, -1.0 to 3.1) in the other prefectures.

CONCLUSION

We estimated the incidence of infantile SMA in an isolated area of Japan. For more precise determination of the incidence of infantile SMA, further studies that include neonatal screening will be needed.

A retrospective cohort study of children with spinal muscular atrophy type 2 receiving anesthesia for intrathecal administration of nusinersen

INTRODUCTION

Spinal muscular atrophy is characterized by loss of motor neurons in the anterior horn of the spinal cord with resultant proximal muscle weakness. Intrathecal nusinersen has revolutionized the treatment of spinal muscular atrophy. We reviewed the perioperative care of 61 anesthetics performed on eight patients with spinal muscular atrophy type 2 who received nusinersen over 30 months in conjunction with nusinersen's phase 3 clinical trials.

METHODS

Anesthesia was induced in all patients with sevoflurane, nitrous oxide, and oxygen (30%) via facemask. A peripheral intravenous line was placed after the loss of consciousness in all but three procedures. General anesthesia was maintained in 58 anesthetics with a propofol infusion at 250-300 μg/kg/min, while the remainder was maintained with inhalational anesthetics. The airway was managed via facemask or nasal cannula in all but two procedures, in whom a laryngeal mask airway was placed. We analyzed patient demographics, duration of anesthesia and of postanesthesia care unit stay, discharge destination, preprocedure oxygen saturation (SaO₂ ), postanesthesia care unit discharge oxygen saturation, and occurrence of unanticipated admission or postdischarge hospitalization.

RESULTS

Eight American Society of Anesthesiologists physical status three patients (3 male: 5 female) with a median age of 4.1 (2.1-7.8) years and median weight of 13.2 (10-24.7) kg, underwent 61 anesthetics for nusinersen administration or sham procedure. There were no intraoperative anesthetic complications of unanticipated cardiovascular instability, major neurologic events, respiratory failure, or death. Anesthesiologists performed 83% of the procedures.

CONCLUSION

Nusinersen has revolutionized the care of patients with spinal muscular atrophy type 2 and anesthesiologists will be involved in its administration. We found that routine anesthetic care was safe and effective.

Spinal muscular atrophy 5Q - Treatment with nusinersen

The Guidelines Project, an initiative of the Brazilian Medical Association, aims to combine information from the medical field in order to standardize producers to assist the reasoning and decision-making of doctors. The information provided through this project must be assessed and criticized by the physician responsible for the conduct that will be adopted, depending on the conditions and the clinical status of each patient.

Evidence in focus: Nusinersen use in spinal muscular atrophy: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology

OBJECTIVE

To identify the level of evidence for use of nusinersen to treat spinal muscular atrophy (SMA) and review clinical considerations regarding use.

METHODS

The author panel systematically reviewed nusinersen clinical trials for patients with SMA and assigned level of evidence statements based on the American Academy of Neurology's 2017 therapeutic classification of evidence scheme. Safety information, regulatory decisions, and clinical context were also reviewed.

RESULTS

Four published clinical trials were identified, 3 of which were rated above Class IV. There is Class III evidence that in infants with homozygous deletions or mutations of SMN1, nusinersen improves the probability of permanent ventilation-free survival at 24 months vs a well-defined historical cohort. There is Class I evidence that in term infants with SMA and 2 copies of SMN2, treatment with nusinersen started in individuals younger than 7 months results in a better motor milestone response and higher rates of event-free survival than sham control. There is Class I evidence that in children aged 2-12 years with SMA symptom onset after 6 months of age, nusinersen results in greater improvement in motor function at 15 months than sham control. Nusinersen was safe and well-tolerated.

CLINICAL CONTEXT

Evidence of efficacy is currently highest for treatment of infantile- and childhood-onset SMA in the early and middle symptomatic phases. While approved indications for nusinersen use in North America and Europe are broad, payer coverage for populations outside those in clinical trials remain variable. Evidence, availability, cost, and patient preferences all influence decision-making regarding nusinersen use.

Respiratory health service utilization of children with neuromuscular disease

OBJECTIVES

To quantify health service utilization including assessment, monitoring, and treatment of respiratory complications of children with neuromuscular disease (NMD), identifying practice variation and adherence to guideline recommendations at a population level.

METHODS

North American population-based cohort study (2003-2015) of children with NMD using hospital diagnostic and physician billing codes within health administrative databases.

RESULTS

We identified 18 163 children with NMD. Mean (SD) age was 7.8 (5.6) years with 40% ≤5; 45% were female. Most common diagnoses were cerebral palsy (50%) and spina bifida (16%); 8% had muscular dystrophy. From fiscal years 2003-2014, 15 600 (86%) children went to an emergency department on average 3.5 times every 3 years; 6575 (36%) for respiratory reasons. 8788 (48%) were admitted to hospital with 2190 (12%) for respiratory reasons and 2451 (13%) required intensive care. Respiratory specialist outpatient visits occurred for 2226 (12%) children on average 6.5 visits every 3 years; 723 (4%) had in-hospital respiratory specialist consultation. Pulmonary function testing was conducted in 3194 (18%) children on average 2.4 times every 3 years; sleep studies in 1389 (8%).

CONCLUSION

In this population-based study of children with NMD, healthcare utilization for respiratory complications was considerable. Frequency of respiratory specialist consultation, monitoring of respiratory function and sleep disordered breathing was variable but on average reflected professional society recommendations. Children with NMD are frequent ED users suggesting a need to improve community and social supports. We did not detect reduced access to respiratory monitoring or specialist consultation in adolescents transitioning to adult services.

Pharmacological c-Jun NH2-Terminal Kinase (JNK) Pathway Inhibition Reduces Severity of Spinal Muscular Atrophy Disease in Mice

Spinal muscular atrophy (SMA) is a severe neurodegenerative disorder that occurs in early childhood. The disease is caused by the deletion/mutation of the survival motor neuron 1 (SMN1) gene resulting in progressive skeletal muscle atrophy and paralysis, due to the degeneration of spinal motor neurons (MNs). Currently, the cellular and molecular mechanisms underlying MN death are only partly known, although recently it has been shown that the c-Jun NH₂-terminal kinase (JNK)-signaling pathway might be involved in the SMA pathogenesis. After confirming the activation of JNK in our SMA mouse model (SMN2+/+; SMNΔ7+/+; Smn−/−), we tested a specific JNK-inhibitor peptide (D-JNKI1) on these mice, by chronic administration from postnatal day 1 to 10, and histologically analyzed the spinal cord and quadriceps muscle at age P12. We observed that D-JNKI1 administration delayed MN death and decreased inflammation in spinal cord. Moreover, the inhibition of JNK pathway improved the trophism of SMA muscular fibers and the size of the neuromuscular junctions (NMJs), leading to an ameliorated innervation of the muscles that resulted in improved motor performances and hind-limb muscular tone. Finally, D-JNKI1 treatment slightly, but significantly increased lifespan in SMA mice. Thus, our results identify JNK as a promising target to reduce MN cell death and progressive skeletal muscle atrophy, providing insight into the role of JNK-pathway for developing alternative pharmacological strategies for the treatment of SMA.

A Semi-Mechanistic Population Pharmacokinetic Model of Nusinersen: An Antisense Oligonucleotide for the Treatment of Spinal Muscular Atrophy

A pharmacokinetic (PK) model was developed for nusinersen, an antisense oligonucleotide (ASO) that is the first approved treatment for spinal muscular atrophy (SMA). The model was built with data from 92 nonhuman primates (NHPs) following intrathecal doses (0.3–7 mg) and characterized the PK in cerebrospinal fluid (CSF), plasma, total spinal cord, brain, and pons. The estimated volumes were 13.6, 937, 4.5, 53.8, and 2.11 mL, respectively. Global sensitivity analysis demonstrated that the CSF‐to‐plasma drug distribution rate (0.09 hour⁻¹) is a major determinant of the maximum nusinersen concentration in central nervous system (CNS) tissues. Physiological age‐based and body weight‐based allometric scaling was implemented with exponent values of −0.08 and 1 for the rate constants and the volume of distribution, respectively. Simulations of the scaled model were in agreement with clinical observations from 52 pediatric phase I PK profiles. The developed model can be used to guide the design of clinical trials with ASOs.

Clinical relevance of terminal Schwann cells: An overlooked component of the neuromuscular junction

The terminal Schwann cell (tSC), a type of nonmyelinating Schwann cell, is a significant yet relatively understudied component of the neuromuscular junction. In addition to reviewing the role tSCs play on formation, maintenance, and remodeling of the synapse, we review studies that implicate tSCs in neuromuscular diseases including spinal muscular atrophy, Miller-Fisher syndrome, and amyotrophic lateral sclerosis, among others. We also discuss the importance of these cells on degeneration and regeneration after nerve injury. Knowledge of tSC biology may improve our understanding of disease pathogenesis and help us identify new and innovative therapeutic strategies for the many patients who suffer from neuromuscular disorders and nerve injuries.

Driven to decay: Excitability and synaptic abnormalities in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron (MN) disease and is clinically characterised by the death of corticospinal motor neurons (CSMNs), spinal and brainstem MNs and the degeneration of the corticospinal tract. Degeneration of CSMNs and MNs leads inexorably to muscle wastage and weakness, progressing to eventual death within 3-5 years of diagnosis. The CSMNs, located within layer V of the primary motor cortex, project axons constituting the corticospinal tract, forming synaptic connections with brainstem and spinal cord interneurons and MNs. Clinical ALS may be divided into familial (∼10% of cases) or sporadic (∼90% of cases), based on apparent random incidence. The emergence of transgenic murine models, expressing different ALS-associated mutations has accelerated our understanding of ALS pathogenesis, although precise mechanisms remain elusive. Multiple avenues of investigation suggest that cortical electrical abnormalities have pre-eminence in the pathophysiology of ALS. In addition, glutamate-mediated functional and structural alterations in both CSMNs and MNs are present in both sporadic and familial forms of ALS. This review aims to promulgate debate in the field with regard to the common aetiology of sporadic and familial ALS. A specific focus on a nexus point in ALS pathogenesis, namely, the synaptic and intrinsic hyperexcitability of CSMNs and MNs and alterations to their structure are comprehensively detailed. The association of extramotor dysfunction with neuronal structural/functional alterations will be discussed. Finally, the implications of the latest research on the dying-forward and dying-back controversy are considered.

Mechanistic studies of a small-molecule modulator of SMN2 splicing

RG-7916 is a first-in-class drug candidate for the treatment of spinal muscular atrophy (SMA) that functions by modulating pre-mRNA splicing of the SMN2 gene, resulting in a 2.5-fold increase in survival of motor neuron (SMN) protein level, a key protein lacking in SMA patients. RG-7916 is currently in three interventional phase 2 clinical trials for various types of SMA. In this report, we show that SMN-C2 and -C3, close analogs of RG-7916, act as selective RNA-binding ligands that modulate pre-mRNA splicing. Chemical proteomic and genomic techniques reveal that SMN-C2 directly binds to the AGGAAG motif on exon 7 of the SMN2 pre-mRNA, and promotes a conformational change in two to three unpaired nucleotides at the junction of intron 6 and exon 7 in both in vitro and in-cell models. This change creates a new functional binding surface that increases binding of the splicing modulators, far upstream element binding protein 1 (FUBP1) and its homolog, KH-type splicing regulatory protein (KHSRP), to the SMN-C2/C3-SMN2 pre-mRNA complex and enhances SMN2 splicing. These findings underscore the potential of small-molecule drugs to selectively bind RNA and modulate pre-mRNA splicing as an approach to the treatment of human disease.

Interventions Targeting Glucocorticoid-Krüppel-like Factor 15-Branched-Chain Amino Acid Signaling Improve Disease Phenotypes in Spinal Muscular Atrophy Mice

The circadian glucocorticoid-Krüppel-like factor 15-branched-chain amino acid (GC-KLF15-BCAA) signaling pathway is a key regulatory axis in muscle, whose imbalance has wide-reaching effects on metabolic homeostasis. Spinal muscular atrophy (SMA) is a neuromuscular disorder also characterized by intrinsic muscle pathologies, metabolic abnormalities and disrupted sleep patterns, which can influence or be influenced by circadian regulatory networks that control behavioral and metabolic rhythms. We therefore set out to investigate the contribution of the GC-KLF15-BCAA pathway in SMA pathophysiology of Taiwanese Smn^−/−;SMN2 and Smn^2B/− mouse models. We thus uncover substantial dysregulation of GC-KLF15-BCAA diurnal rhythmicity in serum, skeletal muscle and metabolic tissues of SMA mice. Importantly, modulating the components of the GC-KLF15-BCAA pathway via pharmacological (prednisolone), genetic (muscle-specific Klf15 overexpression) and dietary (BCAA supplementation) interventions significantly improves disease phenotypes in SMA mice. Our study highlights the GC-KLF15-BCAA pathway as a contributor to SMA pathogenesis and provides several treatment avenues to alleviate peripheral manifestations of the disease. The therapeutic potential of targeting metabolic perturbations by diet and commercially available drugs could have a broader implementation across other neuromuscular and metabolic disorders characterized by altered GC-KLF15-BCAA signaling.

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SMA is a neuromuscular disease characterized by motoneuron loss, muscle abnormalities and metabolic perturbations.

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The regulatory GC-KLF15-BCAA pathway is dysregulated in serum and skeletal muscle of SMA mice during disease progression.

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Modulating GC-KLF15-BCAA signaling by pharmacological, dietary and genetic interventions improves phenotype of SMA mice.

Spinal muscular atrophy (SMA) is a devastating and debilitating childhood genetic disease. Although nerve cells are mainly affected, muscle is also severely impacted. The normal communication between the glucocorticoid (GC) hormone, the protein KLF15 and the dietary branched-chain amino acids (BCAAs) maintains muscle and whole-body health. In this study, we identified an abnormal activity of GC-KLF15- BCAA in blood and muscle of SMA mice. Importantly, targeting GC-KLF15-BCAA activity with an existing drug or a specific diet improved disease progression in SMA mice. Our research uncovers GCs, KLF15 and BCAAs as therapeutic targets to ameliorate SMA muscle and whole-body health.

Painless motor radiculopathy of the cervical spine: clinical and radiological characteristics and long-term outcomes after operative decompression

OBJECTIVE Various neurological diseases are known to cause progressive painless paresis of the upper limbs. In this study the authors describe the previously unspecified syndrome of compression-induced painless cervical radiculopathy with predominant motor deficit and muscular atrophy, and highlight the clinical and radiological characteristics and outcomes after surgery for this rare syndrome, along with its neurological differential diagnoses. METHODS Medical records of 788 patients undergoing surgical decompression due to degenerative cervical spine diseases between 2005 and 2014 were assessed. Among those patients, 31 (3.9%, male to female ratio 4.8 to 1, mean age 60 years) presented with painless compressive cervical motor radiculopathy due to neuroforaminal stenosis without signs of myelopathy; long-term evaluation was available in 23 patients with 49 symptomatic foraminal stenoses. Clinical, imaging, and operative findings as well as the long-term course of paresis and quality of life were analyzed. RESULTS Presenting symptoms (mean duration 13.3 months) included a defining progressive flaccid radicular paresis (median grade 3/5) without any history of radiating pain (100%) and a concomitant muscular atrophy (78%); 83% of the patients were smokers and 17% patients had diabetes. Imaging revealed a predominantly anterior nerve root compression at the neuroforaminal entrance in 98% of stenoses. Thirty stenoses (11 patients) were initially decompressed via an anterior surgical approach and 19 stenoses (12 patients) via a posterior surgical approach. Overall reoperation rate due to new or recurrent stenoses was 22%, with time to reoperation shorter in smokers (p = 0.033). Independently of the surgical procedure chosen, long-term follow-up (mean 3.9 years) revealed a stable or improved paresis in 87% of the patients (median grade 4/5) and an excellent general performance and quality of life. CONCLUSIONS Painless cervical motor radiculopathy predominantly occurs due to focal compression of the anterior nerve root at the neuroforaminal entrance. Surgical decompression is effective in stabilizing or improving motor function with a resulting favorable long-term outcome.

Metalloprotease-mediated cleavage of PlexinD1 and its sequestration to actin rods in the motoneuron disease spinal muscular atrophy (SMA)

Cytoskeletal rearrangement during axon growth is mediated by guidance receptors and their ligands which act either as repellent, attractant or both. Regulation of the actin cytoskeleton is disturbed in Spinal Muscular Atrophy (SMA), a devastating neurodegenerative disease affecting mainly motoneurons, but receptor-ligand interactions leading to the dysregulation causing SMA are poorly understood. In this study, we analysed the role of the guidance receptor PlexinD1 in SMA pathogenesis. We showed that PlexinD1 is cleaved by metalloproteases in SMA and that this cleavage switches its function from an attractant to repellent. Moreover, we found that the PlexinD1 cleavage product binds to actin rods, pathological aggregate-like structures which had so far been described for age-related neurodegenerative diseases. Our data suggest a novel disease mechanism for SMA involving formation of actin rods as a molecular sink for a cleaved PlexinD1 fragment leading to dysregulation of receptor signaling.

Investigation of New Morpholino Oligomers to Increase Survival Motor Neuron Protein Levels in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal-recessive childhood motor neuron disease and the main genetic cause of infant mortality. SMA is caused by deletions or mutations in the survival motor neuron 1 (SMN1) gene, which results in SMN protein deficiency. Only one approved drug has recently become available and allows for the correction of aberrant splicing of the paralogous SMN2 gene by antisense oligonucleotides (ASOs), leading to production of full-length SMN protein. We have already demonstrated that a sequence of an ASO variant, Morpholino (MO), is particularly suitable because of its safety and efficacy profile and is both able to increase SMN levels and rescue the murine SMA phenotype. Here, we optimized this strategy by testing the efficacy of four new MO sequences targeting SMN2. Two out of the four new MO sequences showed better efficacy in terms of SMN protein production both in SMA induced pluripotent stem cells (iPSCs) and SMAΔ7 mice. Further, the effect was enhanced when different MO sequences were administered in combination. Our data provide an important insight for MO-based treatment for SMA. Optimization of the target sequence and validation of a treatment based on a combination of different MO sequences could support further pre-clinical studies and the progression toward future clinical trials.

Trends, goals and outcomes for children and families using early powered mobility in a charitable loan scheme

Purpose

The purpose of this paper is to explore a large data set compiled by a UK charity loan scheme to identify trends and paint a practice-based picture of how young children use early years powered mobility (EYPM).

Design/methodology/approach

Statistical analysis was used to investigate a database of 90 children, ranging in age from 15 to 72 months who completed use of an EYPM device (the Wizzybug, or WB) between April 2011 and December 2015. Goals were set and reviewed, and thematic analysis was used to understand families’ insights into their children’s use of EYPM, using a free-text review form.

Findings

Children’s mean age when joining this free loan scheme was 39.6 months. The later the child started using a Wizzybug, the less likely they were to achieve their goals. A theme of happiness and enjoyment emerged as important for both child and family. The child’s independence translated to independence for the whole family.

Research limitations/implications

The database was operational and incomplete. Lack of a standardised outcome measure was disadvantageous.

Practical implications

Challenges of translating research knowledge into practice are highlighted, supporting the need for more rigorous and standardised outcome measures. Earlier identification of children’s readiness for EYPM is required alongside research and recognition of the holistic benefits of EYPM for all the family.

Originality/value

This research profited from a large data set of young children with long-term access to powered mobility at home.

The Canadian Neuromuscular Disease Registry: Connecting patients to national and international research opportunities

Introduction

Patient registries serve an important role in rare disease research, particularly for the recruitment and planning of clinical trials. The Canadian Neuromuscular Disease Registry was established with the primary objective of improving the future for neuromuscular (NM) patients through the enablement and support of research into potential treatments.

Methods

In this report, we discuss design and utilization of the Canadian Neuromuscular Disease Registry with special reference to the paediatric cohort currently enrolled in the registry.

Results

As of July 25, 2017, there are 658 paediatric participants enrolled in the registry, 249 are dystrophinopathies (229 are Duchenne muscular dystrophy), 57 are myotonic dystrophy participants, 98 spinal muscular atrophy participants and 65 are limb girdle muscular dystrophy. A total of 175 patients have another NM diagnosis. The registry has facilitated 20 clinical trial inquiries, 5 mail-out survey studies and 5 other studies in the paediatric population.

Discussion

The strengths of the registry are discussed. The registry has proven to be an invaluable tool to NM disease research and has increased Canada's visibility as a competitive location for the conduct of clinical trials for NM therapies.

Segmental Spinal Muscular Atrophy Localised to the Lower Limbs: First case from Oman

Spinal muscular atrophy (SMA) is a genetic lower motor neuron disease. It usually involves all of the skeletal muscles innervated by the anterior horn cells of the spinal cord. In rare cases, there is also localised involvement of the spinal cord. We report a 10-year-old boy who presented to the Sultan Qaboos University Hospital, Muscat, Oman, in 2015 with muscle weakness restricted to the lower limbs. The presence of a homozygous deletion within the survival of motor neuron 1 gene confirmed the diagnosis of SMA. To the best of the authors' knowledge, this is the first report of an Omani patient with segmental SMA involving only the lower limbs. Treatment for this rare and relatively benign form of SMA is symptomatic and includes physiotherapy.

Free-Aspire: A new device for the management of airways clearance in patient with ineffective cough

A 3-year-old girl with Spinal Muscular Atrophy type I presented with a right pneumonia. On physical examination pulmonary auscultation revealed an asymmetry of breath sounds between the 2 hemithoraces, owing to decreased breath sounds in the right hemithorax. Blood tests were normal. The initial working diagnosis was a suspected area of mucus accumulation. A treatment with Free Aspire was started. Within a few days, the girl was discharged with a normal physical examination and X-ray study result. Spinal Muscular Atrophy is a rare neuromuscular disorder characterized by loss of motor neurons and progressive muscle wasting. Cough in these patients result ineffective. Free-Aspire is an electromedical machine for removing bronchoalveolar secretions. The case show that Free Aspire in patients with ineffective cough and impaired removal of secretions is a safe and effective device for the removal of bronchial secretions and could be an another help in the management of airway clearance.

Population Pharmacokinetics of Nusinersen in the Cerebral Spinal Fluid and Plasma of Pediatric Patients With Spinal Muscular Atrophy Following Intrathecal Administrations

Nusinersen is an antisense oligonucleotide intended for the treatment of spinal muscular atrophy. The pharmacokinetics of nusinersen, following intrathecal administrations, in the cerebrospinal fluid (CSF) and plasma of 72 pediatric patients (3 months to 17 years) with spinal muscular atrophy across 5 clinical trials was analyzed via population-based modeling. With sparse data in the CSF and profile data in the plasma, a linear 4-compartment model simultaneously described the time-concentration profiles in both matrices. The typical population parameters were: Q_p = 0.572 L/h, Q_CSF = 0.069 L/h, CL_p = 2.50 L/h, CL_CSF = 0.133 L/hr, V_CSF = 0.441 L, V_p = 32.0 L, V_{systemic_tissue} = 429 L, and V_{CNS_tissue} = 258 L. A full covariate modeling approach identified baseline body weight to be a statistically and clinically relevant covariate on V_CSF , V_p , and CL_p . The model predicted that the CSF volume of distribution increased steadily with age from 0 to 2 years but became relatively steady for children >2 years. Simulations from the final model showed that age-based dosing in children under 2 years ensured a more comparable exposure (peak concentration and area under the concentration-time curve) across subjects in the population relative to a fixed dosing scheme. However, because no dose-limiting toxicity has been reported in any of the trials, a fixed-dose scheme (12 mg across all age groups) was recommended. The median terminal half-life of nusinersen in the CSF was determined from the model to be 163 days, which supported infrequent dosing, once every 4 to 6 months in pediatric patients with spinal muscular atrophy.

Low bone mineral density and fractures are highly prevalent in pediatric patients with spinal muscular atrophy regardless of disease severity

Patients with Spinal Muscular Atrophy (SMA) are at risk for poor bone health. The prevalence of fractures, low areal bone mineral density (aBMD; Z-score ≤-2.0) of the lateral distal femur and of osteoporosis by SMA subtype is not known. We aimed to describe the natural history of bone health in patients with SMA prior to bisphosphonate treatment. We reviewed data from 85 eligible patients with SMA ages 12 months to 18 years, seen at a single institution between January 2005 and July 2016. Fracture history was reported at annual clinic visits. aBMD was obtained from dual energy x-ray absorptiometry scans of the lumbar spine, total body, and lateral distal femur. 85% of patients had aBMD Z-scores ≤-2.0 SD and were progressively lower with worsening SMA severity. Longitudinal aBMD Z-scores of the lateral distal femur decreased with age. Fractures occurred in 38% (32/85) of patients with the femur being the most common location (25 of 57 fractures). Thirteen percent of patients fulfilled criteria for osteoporosis. Low aBMD and femur fractures are highly prevalent in all SMA subtypes from a young age; however, few patients met the criteria for osteoporosis. Poor bone health may be an under-recognized comorbidity of SMA.