Spinal muscular atrophies

Effects of nusinersen on motor function in children with spinal muscular atrophy: a retrospective study

Background

Spinal muscular atrophy (SMA) is a genetic progressive neuromuscular disease. Nusinersen is the first disease modifying drug approved to treat patients with SMA. Our study aimed to evaluate the efficacy of nusinersen treatment on motor function in children with SMA.

Methods

A retrospective analysis was conducted on the data of 52 genetically confirmed SMA patients from November 2020 to September 2023. Motor function was assessed based on standardized scales from baseline to 14 months of follow-up.

Results

Of patients in this study, the majority had SMA type 2 (40/52, 76.9%), 5 (9.6%) and 7 (13.5%) patients had SMA types 1 and 3, respectively. The median disease duration was 11 months (range 0-52), and the median age at initiation of treatment was 44.5 months (range 5-192). Motor function of all the patients with SMA improved from baseline to 14 months of follow-up. Mean increases of 4.6-point (p = 0.173), 4.7-point (p = 0.021) and 2.7-point (p = 0.013) were observed from baseline to 14 months of follow-up for the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scores, the Hammersmith Functional Motor Scale Expanded (HFMSE) and the Revised Upper Limb Module (RULM), respectively. Increased disease duration and age of treatment initiation were negatively correlated with the changes in HFMSE scores (r = -0.567, p = 0.043; r = -0.771 and p = 0.002, respectively). Similar results were observed for the RULM scores (r = -0.714, p = 0.014; r = -0.638 and p = 0.035, respectively).

Conclusion

Our study suggested that 14 months of treatment with nusinersen was effective and improved the motor function of children with SMA types 1, 2, or 3. In addition, disease duration and age at treatment initiation were negatively correlated with treatment outcome in the patients.

Potential of Cell-Penetrating Peptide-Conjugated Antisense Oligonucleotides for the Treatment of SMA

Spinal muscular atrophy (SMA) is a severe neuromuscular disorder that is caused by mutations in the survival motor neuron 1 (SMN1) gene, hindering the production of functional survival motor neuron (SMN) proteins. Antisense oligonucleotides (ASOs), a versatile DNA-like drug, are adept at binding to target RNA to prevent translation or promote alternative splicing. Nusinersen is an FDA-approved ASO for the treatment of SMA. It effectively promotes alternative splicing in pre-mRNA transcribed from the SMN2 gene, an analog of the SMN1 gene, to produce a greater amount of full-length SMN protein, to compensate for the loss of functional protein translated from SMN1. Despite its efficacy in ameliorating SMA symptoms, the cellular uptake of these ASOs is suboptimal, and their inability to penetrate the CNS necessitates invasive lumbar punctures. Cell-penetrating peptides (CPPs), which can be conjugated to ASOs, represent a promising approach to improve the efficiency of these treatments for SMA and have the potential to transverse the blood-brain barrier to circumvent the need for intrusive intrathecal injections and their associated adverse effects. This review provides a comprehensive analysis of ASO therapies, their application for the treatment of SMA, and the encouraging potential of CPPs as delivery systems to improve ASO uptake and overall efficiency.

Nusinersen therapy changed the natural course of spinal muscular atrophy type 1: What about spine and hip?

Purpose

Spinal muscular atrophy type 1 has a devastating natural course and presents a severe course marked by scoliosis and hip subluxation in nonambulatory patients. Nusinersen, Food and Drug Administration-approved spinal muscular atrophy therapy, extends survival and enhances motor function. However, its influence on spinal and hip deformities remains unclear.

Methods

In a retrospective study, 29 spinal muscular atrophy type 1 patients born between 2017 and 2021, confirmed by genetic testing, treated with intrathecal nusinersen, and had registered to the national electronic health database were included. Demographics, age at the first nusinersen dose, total administrations, and Children's of Philadelphia Infant Test of Neuromuscular Disorders scores were collected. Radiological assessments included parasol rib deformity, scoliosis, pelvic obliquity, and hip subluxation.

Results

Mean age was 3.7 ± 1.1 (range, 2-6), and average number of intrathecal nusinersen administration was 8.9 ± 2.9 (range, 4-19). There was a significant correlation between Children's of Philadelphia Infant Test of Neuromuscular Disorders score and the number of nusinersen administration (r = 0.539, p = 0.05). The correlation between Children's of Philadelphia Infant Test of Neuromuscular Disorders score and patient age (r = 0.361) or the time of first nusinersen dose (r = 0.39) was not significant (p = 0.076 and p = 0.054, respectively). While 93.1% had scoliosis, 69% had pelvic obliquity, and 60.7% had hip subluxation, these conditions showed no significant association with patient age, total nusinersen administrations, age at the first dose, or Children's of Philadelphia Infant Test of Neuromuscular Disorders scores.

Conclusion

Disease-modifying therapy provides significant improvements in overall survival and motor function in spinal muscular atrophy type 1. However, progressive spine deformity and hip subluxation still remain significant problems in the majority of cases which would potentially need to be addressed.

Adherence and Persistence Among Risdiplam-Treated Individuals with Spinal Muscular Atrophy: A Retrospective Claims Analysis

INTRODUCTION

Spinal muscular atrophy (SMA) is a neuromuscular disease caused by deletions and/or mutations in the survival of motor neuron 1 (SMN1) gene. Risdiplam, the first and only oral SMN2 pre-mRNA splicing modifier, is US Food and Drug Administration-approved for the treatment of pediatric and adult patients with SMA. For patients with SMA, long-term adherence to and persistence with an SMA treatment may be important for achieving maximum clinical benefits. However, real-world evidence on patient adherence to and persistence with risdiplam is limited.

METHODS

This retrospective study examined real-world adherence and persistence with risdiplam from a specialty pharmacy in patients with SMA over a 12-month period. Adherence was estimated by using proportion of days covered (PDC) and was calculated over variable (time between first and last fill) and fixed (time from first fill to study period end) intervals. Persistence was defined as no gap in supply ≥ 90 days. Patients were included if the time between the index date and study observation period was ≥ 12 months, if they initiated risdiplam between August 2020 and September 2022, received ≥ 2 risdiplam fills, and had an SMA diagnosis associated with a risdiplam fill. Subgroup analyses of risdiplam adherence and persistence were performed by age and primary payer type.

RESULTS

The proportion of patients (N = 1636) adherent at 12 months based on variable and fixed interval PDC was 93% and 79%, respectively. Adherence was high among patients on commercial insurance, Medicaid, or Medicare (range 86-96%). Mean persistence was 330.4 days. The highest proportion of patients who were persistent were on Medicaid (81%).

CONCLUSION

These findings demonstrate that patient adherence to and persistence with risdiplam treatment were high, including across all subgroups tested.

Healthcare resource utilisation and direct medical cost for individuals with 5q spinal muscular atrophy in Sweden

BACKGROUND

Spinal muscular atrophy (SMA) is a rare, progressive, neuromuscular disorder. Recent advances in treatment require an updated assessment of burden to inform reimbursement decisions.

OBJECTIVES

To quantify healthcare resource utilisation (HCRU) and cost of care for patients with SMA.

METHODS

Cohort study of patients with SMA identified in the Swedish National Patient Registry (2007-2018), matched to a reference cohort grouped into four SMA types (1, 2, 3, unspecified adult onset [UAO]). HCRU included inpatient admissions, outpatient visits, procedures, and dispensed medications. Direct medical costs were estimated by multiplying HCRU by respective unit costs. Average annual HCRU and medical costs were modelled for SMA versus reference cohorts to estimate differences attributable to the disease (i.e., average treatment effect estimand). The trajectory of direct costs over time were assessed using synthetic cohorts.

RESULTS

We identified 290 SMA patients. Annualised HCRU was higher in SMA patients compared with reference cohorts. Highest risk ratios were observed for inpatient overnight stays for type 1 (risk ratio [RR]: 29.2; 95% confidence interval [CI]: 16.0, 53.5) and type 2 (RR: 23.3; 95% CI: 16.4,33.1). Mean annual direct medical costs per patient for each year since first diagnosis were greatest for type 1 (€114,185 and SMA-attributable: €113,380), type 2 (€61,876 and SMA-attributable: €61,237), type 3 (€45,518 and SMA-attributable: €44,556), and UAO (€4046 and SMA-attributable: €2098). Costs were greatest in the 2-3 years after the first diagnosis for all types.

DISCUSSION AND CONCLUSION

The economic burden attributable to SMA is significant. Further research is needed to understand the burden in other European countries and the impact of new treatments.

Safety and efficacy of growth-friendly instrumentation for early-onset scoliosis in patients with spinal muscular atrophy type 1 in the disease-modifying treatment era

Purpose

To evaluate the safety of growth-friendly instrumentation for early-onset scoliosis (EOS) in patients with spinal muscular atrophy (SMA) type 1 who received disease-modifying treatment (DMT) and analyze short-term efficacy.

Methods

Retrospective search was conducted between 2017 and 2023. Patients with genetically confirmed SMA type 1 who were surgically treated for spinal deformity and receiving DMTs (nusinersen, risdiplam, or onasemnogene abeparvovec) were included. SMA types 2 and 3 and patients who do not receive DMTs were excluded. Clinical and radiographic data were collected at preoperative, postoperative, and latest follow-up visits.

Results

Twenty-eight patients (mean follow-up: 16 months (range 2-41)) were included. The mean age at surgery was 60 months (range 29-96). Fifteen were treated with dual magnetically controlled growing rods (MCGR), four with unilateral MCGR and a contralateral guided growth system, three with Vertical Expandable Prosthetic Titanium Rib (VEPTR®) implants, five with self-distracting systems, and one with traditional dual growing rods. The mean amount of correction was 57% (44°± 17) for scoliosis and 83% (13°± 11) for pelvic obliquity. The mean T1-12 height gain during surgery was 31 mm (±16 mm), while the mean T1 S1 height gain was 51 mm (±24 mm), and instrumented growth was observed during follow-up. Five patients (18%) developed six serious adverse events: three surgical site infections, two anchor failures, and one rod fracture, and all required unplanned reoperations. No neurologic complication, difficulty during nusinersen injections, or respiratory decline was recorded.

Conclusion

We report that spinal deformity in this population can be safely treated with growth-friendly instrumentation, with similar complication rates when compared with SMA type 2.

Estimating mortality in rare diseases using a population-based registry, 2002 through 2019

BACKGROUND

Rare diseases (RD) are a heterogeneous group of diseases, sharing aspects of complexity. Prognosis is variable, even in individuals with the same disease. Real-world data on RD as a whole are scarce. The aim of this study is to provide data on mortality and survival for a substantial group of RD deriving from a population-based registry, which covers the Veneto region in Italy (4.9 million inhabitants).

RESULTS

During the study period, 3367 deaths occurred, mainly in males (53.9%), elderly patients (63.5%) and patients with diseases having a reported prevalence of 1-9/100000 (65.6%). When standardizing by age, the mortality ratio was higher in RD patients than in the general population, SMR = 1.93 (95% CI 1.84-2.11), with an observed gender difference, 2.01 (95% CI 1.88-2.29) in females and 1.86 (95% CI 1.73-2.10) in males. The lowest survival rates are experienced by patients with rare neurologic diseases, rare skin diseases and rare systemic or rheumatologic diseases, 58%, 68% and 81%, respectively, after a 15-year observation period. It should be noted that only 18% of patients diagnosed with motor neuron diseases were alive after 15 years from diagnosis.

CONCLUSIONS

Despite progress in diagnosis, treatment and care in recent years, RD patients globally have higher mortality rates and reduced survival compared to the general population, with specific variations according to gender, age and disease group.

Health Care Resource Utilization and Costs for Patients with Spinal Muscular Atrophy: Findings from a Retrospective US Claims Database Analysis

INTRODUCTION

Spinal muscular atrophy (SMA) is a neurogenic disorder associated with progressive loss of muscle function, respiratory failure, and premature mortality. This study aimed to describe and compare real-world health care resource utilization (HCRU) and costs for US patients with SMA treated with disease-modifying treatments, including onasemnogene abeparvovec, nusinersen, and/or risdiplam.

METHODS

This study used claims and structured electronic medical record data from the HealthVerity claims database (January 1, 2017-March 31, 2021). Eligible patients were aged ≤ 2 years at index (treatment initiation or switch), diagnosed with SMA, had ≥ 1 pharmacy/medical claim for onasemnogene abeparvovec, nusinersen, and/or risdiplam, and continuous enrollment ≥ 1 month pre- and ≥ 2 months post-index. SMA-related HCRU and costs during the study period (> 12 months post-index) were compared between treatment groups before and after propensity score weighting. Costs were adjusted to 2021 USD.

RESULTS

Of 74 included patients, 62 (83.8%) received nusinersen and 12 (16.2%) received onasemnogene abeparvovec (monotherapy, n = 9; onasemnogene abeparvovec after nusinersen [switching], n = 3). After weighting, nusinersen-treated patients had greater annual numbers of inpatient (mean 5.3 nusinersen vs. 1.8 onasemnogene abeparvovec) and emergency department (mean 3.0 nusinersen vs. 1.5 onasemnogene abeparvovec; p < 0.05) visits, and greater annual SMA-related medical costs (mean $78,446 nusinersen vs. $29,438 onasemnogene abeparvovec; mean difference $49,007, p < 0.05) than onasemnogene abeparvovec-treated patients. Onasemnogene abeparvovec-treated patients incurred greater SMA-treatment pharmacy costs than nusinersen-treated patients (mean $2,241,875 onasemnogene abeparvovec vs. $693,191 nusinersen; mean difference $1,548,684, p < 0.05).

CONCLUSIONS

SMA is associated with substantial economic burden. Patients treated with onasemnogene abeparvovec had greater SMA treatment-related pharmacy costs but lower SMA-related HCRU and medical costs compared with patients receiving nusinersen monotherapy.

Spinal Muscular Atrophy: The Past, Present, and Future of Diagnosis and Treatment

Spinal muscular atrophy (SMA) is a lower motor neuron disease with autosomal recessive inheritance. The first cases of SMA were reported by Werdnig in 1891. Although the phenotypic variation of SMA led to controversy regarding the clinical entity of the disease, the genetic homogeneity of SMA was proved in 1990. Five years later, in 1995, the gene responsible for SMA, SMN1, was identified. Genetic testing of SMN1 has enabled precise epidemiological studies, revealing that SMA occurs in 1 of 10,000 to 20,000 live births and that more than 95% of affected patients are homozygous for SMN1 deletion. In 2016, nusinersen was the first drug approved for treatment of SMA in the United States. Two other drugs were subsequently approved: onasemnogene abeparvovec and risdiplam. Clinical trials with these drugs targeting patients with pre-symptomatic SMA (those who were diagnosed by genetic testing but showed no symptoms) revealed that such patients could achieve the milestones of independent sitting and/or walking. Following the great success of these trials, population-based newborn screening programs for SMA (more precisely, SMN1-deleted SMA) have been increasingly implemented worldwide. Early detection by newborn screening and early treatment with new drugs are expected to soon become the standards in the field of SMA.

Clinical and Functional Characteristics of a New Phenotype of SMA Type I among a National Sample of Spanish Children: A Cross-Sectional Study

Spinal Muscular Atrophy (SMA) type I has classically presented extremely severe clinical features. New pharmacological treatments have led to a new phenotype of SMA. The aim of this study was to describe the current health and functional status of children with SMA. A cross-sectional study was conducted based on the STROBE guidelines. Patient questionnaires and standardized tools were used. A descriptive analysis was conducted establishing the proportions of subjects for each of the characteristics of interest. In total, 51 genetically confirmed SMA type I subjects were included. Fifty-seven percent received oral feeding, 33% received tube feeding and 10% combined both. Moreover, 21.6% had tracheostomies, and 9.8% needed more than 16 h/d ventilatory support. Regarding orthopedic status, 66.7% had scoliosis, and 68.6% had hip subluxation or dislocation. Up to 67% were able to sit independently, 23.5% walked with support and one child walked independently. Current SMA type I is a different entity from the classic phenotype but also from types II and III. In addition, no differences were found between SMA type I subgroups. These findings may enable the professionals involved in the care of these patients to improve their interventions in terms of prevention and rehabilitation measures for these children.

Effectiveness of Nusinersen in Type 1, 2 and 3 Spinal Muscular Atrophy: Croatian Real-World Data

(1) Background: To investigate the real-world effectiveness and safety profile of nusinersen in Croatian paediatric and adult spinal muscular atrophy (SMA) patients. (2) Methods: A retrospective and anonymous collection of relevant demographic and clinical data for all Croatian SMA patients treated with nusinersen and reimbursed by the Croatian Health Insurance Fund (CHIF) between April 2018 and February 2022 was performed through searching the CHIF database and studying the associated reimbursement documentation. All patients who received at least one dose of nusinersen were included in the baseline clinical-demographic overview and safety analysis, whereas only subjects who had completed six doses were included in the effectiveness analysis. (3) Results: Fifty-two patients [61.5% male; median age 13.4 (0.1-51.1) yr.] received nusinersen treatment. In SMA type 1 and type 3 paediatric patients, statistically significant motor function improvement (CHOP INTEND 10.8 ± 10.3 vs. 20.0 ± 15.8, p = 0.003; HFMSE 49.6 ± 7.9 vs. 53.1 ± 7.7, p = 0.008; respectively) was achieved immediately after 4 loading doses of nusinersen and remained statistically significant onwards. Average improvements in HFMSE motor performance in SMA type 2 patients after four, five, and six doses of nusinersen were +6.0, +10.5, and +11.0 points, respectively. In SMA type 3 adult patients, no significant improvement in RHS motor performance or the 6-Minute Walk Test (MWT) was demonstrated. During the study period, 437 doses were administered without any new safety concerns appearing. (4) Conclusions: Our RWD findings indicate that nusinersen is an effective and safe treatment in a heterogeneous group of paediatric patients with all types of SMA; however, no significant benefit (but only RHS and 6MWT maintenance) was demonstrated in SMA type 3 patients who started nusinersen after >18 years of age.

How is Physical Activity Measured in Spinal Muscular Atrophy and Duchenne Muscular Dystrophy?

BACKGROUND

Physical activity (PA) provides many substantial benefits to help reduce risk for cardiometabolic disease, improve cognitive function, and improve quality of life. Individuals with neuromuscular disorders (NMDs), such as spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD) are characterized by muscular weakness and fatigue, which limits the capacity to reach the recommended guidelines of PA. Measuring PA in these populations can provide insight to participation in daily activities, track disease progression, and monitor efficacy of drug treatments.

OBJECTIVE

The objective of this study was to identify how PA is measured in SMA and DMD using instrumented and self-report methods, and how these methods are employed in ambulatory and non-ambulatory groups.

METHODS

A scoping review was performed to identify studies that reported PA in these neuromuscular disorders. Inclusion was determined after a multi-stage review process by several reviewers, followed by an in-depth analysis of metrics reported by each tool that was used.

RESULTS

A total of nineteen studies were identified and included in this review. Sixteen studies included instrumented measures and four studies utilized self-reported measures, with eleven studies also reporting PA information from a non-ambulatory group. A variety of metrics have been reported using both classes of measurement tools.

CONCLUSION

Although a wide variety of research exists that details both instrumented and self-reported measurement tools, feasibility, cost, and study aims are important factors to consider in addition to testing methodology when selecting which type of tool to use. We recommend using a combination of instrumented and self-report measures to provide context to the PA measured in these populations. Improvements in both instrumented and self-report methodologies will add valuable knowledge about the disease burden and efficacy of treatment and disease management methods in SMA and DMD.

A Mixed-method Approach to Develop an Ambulatory Module of the SMA Independence Scale

BACKGROUND

Limited qualitative data exist on the symptoms and impacts of spinal muscular atrophy (SMA) experienced by ambulant individuals. An ambulant module of the SMA Independence Scale (SMAIS) was developed to quantify the assistance required to perform everyday mobility-related activities.

OBJECTIVE

The objective of this study was to develop a patient-centered module that provides key insights into what constitutes independence for ambulant and near-ambulant individuals with SMA.

METHODS

A stepwise, mixed-method approach was used. Semi-structured interviews were conducted in three waves with individuals with SMA and caregivers of children with SMA who were ambulant or near-ambulant (can walk ≥5 steps with support). Wave 1 interviews (n = 20) focused on concept elicitation. Wave 2 and 3 interviews (n = 15, both) involved completion and cognitive debriefing of items generated based on Wave 1 interviews. Therapeutic area experts were consulted throughout all key steps of the study. In particular, feedback was provided for item refinement and response option decisions. A macro-level preliminary, exploratory analysis, using Rasch Measurement Theory (RMT), provided insight on measurement properties.

RESULTS

Wave 1 resulted in 42 mobility and 11 instrumental activity of daily living (iADL) items. During Wave 2, participants defined independence as completing a task with supportive aids but without help from another person, leading to item refinement and modifications to the response scale. Lack of conceptual relevance and ceiling effects led to the removal of all iADL items after Wave 2, and 41 mobility items were tested in Wave 3. Final exploratory RMT and item refinement to reduce overlap led to a 27-item set related to mobility tasks.

CONCLUSIONS

Our study provides preliminary support for using the 27-item SMAIS-Ambulatory Module for ambulant or near-ambulant individuals with SMA. Larger-scale analyses to further assess the psychometric properties of the scale are warranted.

Disease Modifying Therapies for the Management of Children with Spinal Muscular Atrophy (5q SMA): An Update on the Emerging Evidence

SMA (5q SMA) is an autosomal recessive neuromuscular disease with an estimated incidence of approximately 1 in 11,000 live births, characterized by progressive degeneration and loss of α-motor neurons in the spinal cord and brain stem, resulting in progressive muscle weakness. The disease spectrum is wide, from a serious congenital to a mild adult-onset disease. SMA is caused by biallelic mutations in the SMN1 gene and disease severity is modified primarily by SMN2 copy number. Before the advent of specific disease altering treatments, SMA was the second most common fatal autosomal recessive disorder after cystic fibrosis and the most common genetic cause of infant mortality. Nusinersen, risdiplam, and onasemnogene abeparvovec are presently the only approved disease modifying therapies for SMA, and the aim of this review is to discuss their mode of action, effects, safety concerns, and results from real-world experience. All exert their action by increasing the level of SMN protein in lower motor neuron. Nusinersen and risdiplam by modifying the SMN2 gene product, and onasemnogene abeparvovec by delivering SMN1 gene copies into cells. All have an established clinical efficacy. An important feature shared by all three is that early intervention is associated with a better treatment outcome, such that in cases where treatment is initiated in an early pre-symptomatic period, it may result in normal – or almost normal – motor development. Thus, early diagnosis followed by swift initiation of treatment is fundamental for the treatment response and consequently long-term prognosis in SMA type 1, and probably SMA type 2. The same principle similarly applies to the milder phenotypes. All three therapies are relatively novel, with risdiplam being the latest addition. Except for nusinersen, real-world data are still scarce, and long-term data are quite naturally lacking.

DNA Double-Strand Breaks as Pathogenic Lesions in Neurological Disorders

The damage and repair of DNA is a continuous process required to maintain genomic integrity. DNA double-strand breaks (DSBs) are the most lethal type of DNA damage and require timely repair by dedicated machinery. DSB repair is uniquely important to nondividing, post-mitotic cells of the central nervous system (CNS). These long-lived cells must rely on the intact genome for a lifetime while maintaining high metabolic activity. When these mechanisms fail, the loss of certain neuronal populations upset delicate neural networks required for higher cognition and disrupt vital motor functions. Mammalian cells engage with several different strategies to recognize and repair chromosomal DSBs based on the cellular context and cell cycle phase, including homologous recombination (HR)/homology-directed repair (HDR), microhomology-mediated end-joining (MMEJ), and the classic non-homologous end-joining (NHEJ). In addition to these repair pathways, a growing body of evidence has emphasized the importance of DNA damage response (DDR) signaling, and the involvement of heterogeneous nuclear ribonucleoprotein (hnRNP) family proteins in the repair of neuronal DSBs, many of which are linked to age-associated neurological disorders. In this review, we describe contemporary research characterizing the mechanistic roles of these non-canonical proteins in neuronal DSB repair, as well as their contributions to the etiopathogenesis of selected common neurological diseases.

Risdiplam: A Review in Spinal Muscular Atrophy

Risdiplam (Evrysdi^®) is the first oral drug developed to treat spinal muscular atrophy (SMA) and is approved in multiple countries worldwide. It is approved for the treatment of SMA in patients aged ≥ 2 months in the USA and the EU, with this approval further specified in the EU for the treatment of 5q-autosomal recessive SMA with a clinical diagnosis of SMA types 1, 2, or 3 or with one to four survival motor neuron 2 (SMN2) copies. As an SMN2 pre-mRNA splicing modifier, risdiplam increases the production of full-length SMN protein, the lack of which drives the pathophysiology of SMA. In phase 2/3 clinical trials, risdiplam significantly improved motor function in infants with SMA type 1 and in patients aged 2-25 years with SMA types 2 or 3. These motor improvements were maintained with up to 2 years of treatment with risdiplam. Risdiplam was generally well tolerated, with a favourable benefit to risk balance. As an oral drug, risdiplam provides a convenient and useful treatment option across a broad range of patient ages and subtypes of SMA.

Restoration of Nusinersen Levels Following Treatment Interruption in People With Spinal Muscular Atrophy: Simulations Based on a Population Pharmacokinetic Model

BACKGROUND

Nusinersen is approved for the treatment of spinal muscular atrophy. The most common approved dosing regimen is four intrathecal loading doses of nusinersen 12 mg; the first three are administered at 14-day intervals followed by a fourth dose 30 days later, and then 12-mg maintenance doses are administered every 4 months thereafter. Interruption of nusinersen treatment in the maintenance dosing phase might occur for a number of clinical reasons.

OBJECTIVE

The objective of this report is to describe dosing regimens that allow for the most rapid restoration of steady-state concentrations of nusinersen in the cerebrospinal fluid (CSF) following a treatment interruption during maintenance dosing.

METHODS

Population pharmacokinetic models using integrated pharmacokinetic data from ten nusinersen clinical trials that included a broad range of participants with spinal muscular atrophy treated with intrathecal nusinersen were used to investigate different durations of treatment interruptions during maintenance treatment. Potential dosing regimens for re-initiation of nusinersen were evaluated, with the goal of achieving the quickest restoration of steady-state nusinersen CSF concentrations without exceeding maximal CSF exposures observed during the initial loading period.

RESULTS

Our pharmacokinetic modeling indicates the following regimen will lead to optimal restoration of nusinersen CSF levels after treatment interruption: two doses of nusinersen should be administered at 14-day intervals following treatment interruptions of ≥ 8 to < 16 months since the last dose, and three doses of nusinersen at 14-day intervals for treatment interruptions of ≥ 16 to < 40 months since the last maintenance dose, with subsequent maintenance dosing every 4 months in both instances. After treatment interruptions of ≥ 40 months, the full loading regimen will rapidly restore nusinersen CSF levels.

CONCLUSIONS

Prolonged treatment interruptions lead to suboptimal CSF levels of nusinersen. The optimal regimen to restore nusinersen CSF levels depends on the interval since the last maintenance dose was administered.

Current and Future Prospects for Gene Therapy for Rare Genetic Diseases Affecting the Brain and Spinal Cord

In recent years, gene therapy has been raising hopes toward viable treatment strategies for rare genetic diseases for which there has been almost exclusively supportive treatment. We here review this progress at the pre-clinical and clinical trial levels as well as market approvals within diseases that specifically affect the brain and spinal cord, including degenerative, developmental, lysosomal storage, and metabolic disorders. The field reached an unprecedented milestone when Zolgensma® (onasemnogene abeparvovec) was approved by the FDA and EMA for in vivo adeno-associated virus-mediated gene replacement therapy for spinal muscular atrophy. Shortly after EMA approved Libmeldy®, an ex vivo gene therapy with lentivirus vector-transduced autologous CD34-positive stem cells, for treatment of metachromatic leukodystrophy. These successes could be the first of many more new gene therapies in development that mostly target loss-of-function mutation diseases with gene replacement (e.g., Batten disease, mucopolysaccharidoses, gangliosidoses) or, less frequently, gain-of-toxic-function mutation diseases by gene therapeutic silencing of pathologic genes (e.g., amyotrophic lateral sclerosis, Huntington's disease). In addition, the use of genome editing as a gene therapy is being explored for some diseases, but this has so far only reached clinical testing in the treatment of mucopolysaccharidoses. Based on the large number of planned, ongoing, and completed clinical trials for rare genetic central nervous system diseases, it can be expected that several novel gene therapies will be approved and become available within the near future. Essential for this to happen is the in depth characterization of short- and long-term effects, safety aspects, and pharmacodynamics of the applied gene therapy platforms.

Cerebrospinal Fluid and Clinical Profiles in Adult Type 2-3 Spinal Muscular Atrophy Patients Treated with Nusinersen: An 18-Month Single-Centre Experience

BACKGROUND AND OBJECTIVES

Nusinersen was approved as the first disease-modifying therapy in spinal muscular atrophy (SMA). Our aim was to analyse therapy-related changes in cerebrospinal fluid (CSF) and serum parameters of adult type 2-3 SMA and to correlate biochemical data with motor functional status.

METHODS

Nine adult SMA type 2-3 patients and ten control subjects without neurodegenerative diseases were included in our single-centre study. Cross-sectional analysis of CSF routine parameters, CSF neurofilament light chain, CSF Tau, CSF phospho-Tau and serum creatinine was performed between SMA patients at baseline (T0) and control subjects. The above-mentioned fluid parameters were longitudinally analysed in the SMA cohort after loading dose (T1) and after four maintenance doses (T2, T3, T4, T5). Hammersmith Functional Motor Scale Expanded (HFMSE), Revised Upper Limb Module (RULM) and the 6-minute walking test (6MWT) were used to evaluate motor outcomes.

RESULTS

Improvements in HFMSE, RULM and 6MWT were observed only after the loading dose of nusinersen. No significant differences in routine CSF parameters and CSF markers of neurodegeneration were found between SMA patients and control subjects. Serum creatinine levels were significantly lower in SMA patients than in control subjects. CSF/serum albumin ratio (Qalb) significantly increased from T0 to each time point, without any further increase after the maintenance doses. Persistent systemic oligoclonal bands (OCBs) were found in five patients from baseline. Three more patients developed persistent systemic OCBs from T1; one patient showed intrathecal OCBSs from baseline to T5. Markers of neurodegeneration did not change during the follow-up and did not correlate with motor scores at baseline and at each timepoint. Serum creatinine levels significantly correlated with HFMSE and RULM at each time point.

CONCLUSIONS

The increase of the Qalb values and the development of systemic OCBs in some SMA patients could be due to repeated lumbar puncture and to the immunogenic effect of nusinersen. On the other hand, the presence of OCBs in serum and/or CSF at baseline should be further investigated. Furthermore, biomarkers of neurodegeneration did not play a prognostic role in our cohort of adult SMA patients.

Nusinersen, an exon 7 inclusion drug for spinal muscular atrophy: A minireview

Spinal muscular atrophy is an autosomal recessive neuromuscular disease with incidence of 1 in 5000 to 10000 live births and is produced by homozygous deletion of exons 7 and 8 in the SMN1 gene. The SMN1 and SMN2 genes encode the survival motor neuron protein, a crucial protein for the preservation of motor neurons. Use of the newer drug, Nusinersen, from early infancy has shown improvement in clinical outcomes of spinal muscular atrophy patients.

The respiratory impact of novel therapies for spinal muscular atrophy

The phenotype of spinal muscular atrophy (SMA) has been changing with the recent availability of three FDA-approved treatments: intrathecal nusinersen, intravenous onasemnogene abeparvovec-xioi, and enteral risdiplam. The degree of improvement in muscle strength and respiratory health varies with SMA genotype, severity of baseline neuromuscular and pulmonary impairment, medication used, and timing of the first dose. A spectrum of pulmonary outcomes has been reported with these novel medications when used early and in conjunction with proactive multidisciplinary management of comorbidities. In this review, we summarize the reported impact of these novel therapies on pulmonary well-being and the improving trajectory of pulmonary morbidity, compared to the natural history of SMA. The importance of ongoing clinical monitoring albeit the improved phenotype is reiterated. We also discuss the limitations of the current SMA-therapy trials and offer suggestions for future clinical-outcome studies and long-term monitoring.

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.

Is cerebrospinal fluid amyloid-β42 a promising biomarker of response to nusinersen in adult spinal muscular atrophy patients?

Introduction

Nusinersen was approved as the first treatment for all types of spinal muscular atrophy (SMA), including adults with SMA types 2 and 3. Robust biomarkers of treatment response in SMA adults are lacking. Our aim was to examine cerebrospinal fluid (CSF) amyloid‐β40 (Aβ40) and amyloid‐β42 (Aβ42) peptides as biomarkers of treatment response.

Methods

Eight patients with SMA types 2 and 3 were recruited consecutively in a single‐center study. CSF was sampled at baseline, after a loading dose, and after three maintenance doses. Levels of Aβ42 and Aβ40 were evaluated for each CSF sampling. Wilcoxon matched‐pairs signed‐rank test was used to detect longitudinal changes.

Results

CSF levels of Aβ42 increased from baseline to day 420 (95% confidence interval, P = .018), with a significant increase at days 180 and 420 compared with days 0 and 300, respectively (95% confidence interval, P = .012 and P = .018).

Discussion

The maintenance and promotion of wellness of residual motor neurons mediated by the restored level of SMN protein due to nusinersen could result in an increased level of amyloid peptides.

Nusinersen Wearing-Off in Adult 5q-Spinal Muscular Atrophy Patients

The antisense oligonucleotide nusinersen was the first drug treatment available for all types of 5q-spinal muscular atrophy (SMA). The dosing regime has been derived from pivotal clinical trials in infants and children. The efficacy of nusinersen in severely affected adult SMA patients is still questionable, as no placebo-controlled trials have been conducted. In the present study, we systematically examined wearing-off phenomena during nusinersen maintenance dosing using a patient-centered approach. We found that adult SMA patients perceived wearing-off after nearly half of 51 investigated nusinersen administrations, primarily within the last month prior to the next administration. Symptoms and functions affected were mainly general strength and arm and leg muscle function next to endurance and independence in daily routine. Lack of walking ability and higher body mass index were characteristic phenotypic features in patients with consistent wearing-off effects. We assume that specific SMA phenotypes might benefit from higher dosing, shorter treatment intervals, change of treatment administration or a combination of all. Efforts towards treatment optimization may result in higher efficacy in distinct phenotypes.

Treatment satisfaction in 5q-spinal muscular atrophy under nusinersen therapy

Background:

Nusinersen was the first approved disease-modifying therapy for all 5q-spinal muscular atrophy (SMA) patients regardless of age or disease severity. Its efficacy in adults has recently been demonstrated in a large cohort by motor outcome measures, which were only partially suitable to detect changes in very mildly or severely affected patients. Patient-reported outcome measures (PROs) have been suggested as a valuable addition. Here, we aimed to assess treatment satisfaction and investigate whether it may be a useful PRO to monitor SMA patients.

Methods:

We enrolled 91 mainly adult 5q-SMA patients treated with nusinersen in a national, multicenter, cross-sectional observational study. 21 patients underwent longitudinal follow up. Patients’ satisfaction with treatment in four dimensions (global, effectiveness, convenience, side effects) was assessed by the Treatment Satisfaction Questionnaire for Medication German version 1.4 (TSQM-1.4^©) and related to clinical parameters, motor scores, and treatment duration.

Results:

More than 90% of SMA patients were consistently satisfied over a median treatment duration of 10 months. Highest mean scores were observed in the dimensions ‘side effects,’ ‘global satisfaction,’ and ‘effectiveness’ (93.5 ± 14.8 versus 73.1 ± 21.0 and 64.8 ± 20.6, respectively). Patients’ satisfaction with the convenience of treatment was considerably lower (43.6 ± 20.2). Interestingly, satisfaction with the effectiveness was higher in ambulatory (p = 0.014) compared with non-ambulatory patients and directly correlated to motor outcome measures. Five non-ambulatory patients withdrew from therapy. All of them presented with a deterioration of motor outcome measures and reported dissatisfaction with treatment effectiveness and convenience.

Conclusion:

Most patients were satisfied with nusinersen treatment effectiveness. Less severely affected patients indicated higher satisfaction. The TSQM-1.4^© helped to identify therapy non-responders, who mainly addressed dissatisfaction with effectiveness and convenience. We suggest introducing the TSQM-1.4^© as an additional PRO in SMA into clinical practice.

Population pharmacokinetics-based recommendations for a single delayed or missed dose of nusinersen

Nusinersen is an antisense oligonucleotide approved for the treatment of spinal muscular atrophy. The drug is given intrathecally at 12 mg, beginning with 3 loading doses at 2-week intervals, a fourth loading dose 30 days thereafter, and maintenance doses at 4-month intervals. This population pharmacokinetic model was developed to clarify how to maintain targeted nusinersen exposure after an unforeseen one-time delay or missed dose. Simulations demonstrated that the impact of a one-time delay in dosing or a missed dose on median cerebrospinal fluid exposures depended on duration of interruption and the regimen phase in which it occurred. Delays in loading doses delayed reaching the peak trough concentration by approximately the duration of the interruption. Resumption of the regimen as soon as possible resulted in achieving steady state trough concentration upon completion of the loading phase. A short delay (30-90 days) during the maintenance phase led to prolonged lower median cerebrospinal fluid concentration if all subsequent doses were shifted by the same 4-month interval. However, administration of the delayed dose, followed by the subsequent dose as originally scheduled, rapidly restored trough concentration. If a dose must be delayed, patients should return to the original dosing schedule as soon as possible.

Filling the gaps in knowledge translation: Physical therapy recommendations for individuals with spinal muscular atrophy compared to standard of care guidelines

This study describes the current landscape of physical therapy practice recommendations in the United States for children with spinal muscular atrophy (SMA) and their relationship to current SMA standard of care (SMA-SOC) guidelines. Pediatric physical therapists were surveyed to determine their knowledge of SMA-SOC guidelines, and the type, duration and frequency of intervention they recommend for children with SMA, as well as perceived barriers and facilitators to progress in physical therapy. Physical therapists recommend five key intervention areas for individuals with SMA; however discrepancies exist between the SOC recommended intervention parameters and respondents' reported frequency and duration of recommendations. After individuals with SMA initiated disease modifying pharmacotherapies, a majority of physical therapist respondents recommended increases in both frequency and duration of interventions. Nearly all respondents reported that familiarity with SOC guidelines was beneficial to their practice. The primary facilitator to progress was parent/caregiver support, while the primary barrier was limited access to resources. Variation in practice exists regarding care for those with SMA, particularly in the areas of frequency and duration of specific interventions. These findings can guide educational initiatives, identify future research needs and further inform SMA-SOC and best-practice rehabilitation management.

In Search of a Cure: The Development of Therapeutics to Alter the Progression of Spinal Muscular Atrophy

Until the recent development of disease-modifying therapeutics, spinal muscular atrophy (SMA) was considered a devastating neuromuscular disease with a poor prognosis for most affected individuals. Symptoms generally present during early childhood and manifest as muscle weakness and progressive paralysis, severely compromising the affected individual’s quality of life, independence, and lifespan. SMA is most commonly caused by the inheritance of homozygously deleted SMN1 alleles with retention of one or more copies of a paralog gene, SMN2, which inversely correlates with disease severity. The recent advent and use of genetically targeted therapies have transformed SMA into a prototype for monogenic disease treatment in the era of genetic medicine. Many SMA-affected individuals receiving these therapies achieve traditionally unobtainable motor milestones and survival rates as medicines drastically alter the natural progression of this disease. This review discusses historical SMA progression and underlying disease mechanisms, highlights advances made in therapeutic research, clinical trials, and FDA-approved medicines, and discusses possible second-generation and complementary medicines as well as optimal temporal intervention windows in order to optimize motor function and improve quality of life for all SMA-affected individuals.

A novel Xp11.22-22.33 deletion suggesting a possible mechanism of congenital cervical spinal muscular atrophy

BACKGROUND

Congenital cervical spinal muscular atrophy (CCSMA) is a rare, nonprogressive, neurogenic disorder characterized by symmetric arthrogryposis and motor deficits mainly confined to upper extremities. Since its first proposal by Darwish et al. 39 years ago, only few cases have ever been reported. Vascular insult to the anterior horn of cervical spinal cord during fetal development was speculated to be the cause, however, the exact pathogenesis is still not well understood.

METHODS

In this study, whole-exome sequencing (WES) and copy number variation (CNV) analysis were conducted on a definitive CCSMA patient, confirmed by the clinical manifestations and other supplementary examinations.

RESULTS

On physical examination, the patient was mainly characterized by symmetric, congenital, nonprogressive contractures, hypotonia, and muscle weakness mainly confined to the upper limbs, which were further supported by MRI and electromyography. Neuromuscular biopsy of the deltoid muscle demonstrated the type 1 myofiber predominance without any infiltration of inflammatory cells. The WES and CNV analysis unveiled a de novo Xp11.22-22.33 deletion. On further examination of the genes contained within this segment, we recognize UBA1 gene as the most likely pathogenic gene. Ubiquitin-like modifier activating enzyme 1 is encoded by UBA1 gene (MIM 314370) located in Xp11.3 and is a critical protein that plays a vital role in ubiquitin-proteasome system and autophagy. It is well documented that UBA1 gene mutation causes X-linked infantile spinal muscular atrophy (XL-SMA), which manifests phenotypes of arthrogryposis, hypotonia, and myopathic face. Type 2 XL-SMA, which follows a nonprogressive and nonlethal course is very similar to the presentations of CCSMA.

CONCLUSION

The phenotypic similarities between this CCSMA case and XL-SMA prompt us to hypothesize a possible connection between UBA1 gene deficit and the pathogenesis of CCSMA. Our study is the first to demonstrate that CCSMA might have a genetic etiology, thus, expanding our insights into the underlying cause of CCSMA.

Acute flaccid myelitis: cause, diagnosis, and management

Acute flaccid myelitis (AFM) is a disabling, polio-like illness mainly affecting children. Outbreaks of AFM have occurred across multiple global regions since 2012, and the disease appears to be caused by non-polio enterovirus infection, posing a major public health challenge. The clinical presentation of flaccid and often profound muscle weakness (which can invoke respiratory failure and other critical complications) can mimic several other acute neurological illnesses. There is no single sensitive and specific test for AFM, and the diagnosis relies on identification of several important clinical, neuroimaging, and cerebrospinal fluid characteristics. Following the acute phase of AFM, patients typically have substantial residual disability and unique long-term rehabilitation needs. In this Review we describe the epidemiology, clinical features, course, and outcomes of AFM to help to guide diagnosis, management, and rehabilitation. Future research directions include further studies evaluating host and pathogen factors, including investigations into genetic, viral, and immunological features of affected patients, host-virus interactions, and investigations of targeted therapeutic approaches to improve the long-term outcomes in this population.

2020 Update to Spinal Muscular Atrophy Management in Saudi Arabia

Novel therapeutic strategies have shown some promise in treating spinal muscular atrophy (SMA). However, the outcomes and acceptance of these new strategies are yet to be explored. We aimed to investigate physicians' opinions and perceptions toward management strategies of SMA across Saudi Arabia. This is a cross-sectional survey using a self-administered, structured questionnaire sent to physicians who care for SMA patients during the Saudi Pediatric Neurology Society annual conference. A total of 72 clinicians of different neurological subspecialties were included. 48.6% prescribed nusinersen to their patients, with 39% of them having patients started on nusinersen. Though, 8.3% prescribed onasemnogene abeparvovec for 1-3 patients, while none of their patients started on the treatment. 64.3% stated that the only treatment available for SMA in their settings is supportive care. Around 69.4% described having a moderate to high knowledge on SMA gene therapy, and 79.2% would recommend it. 48.6% confirmed they would prescribe gene therapy at the age of 6 months, and 78.3% would prescribe it for type-I SMA. Pediatric neurologists are receptive to novel and innovative therapies for SMA in Saudi Arabia. However, the high treatment acquisition cost, strict regulations, logistical issues, and budget constraints delay their adoption and implementation.

Circulating microRNAs as potential biomarkers and therapeutic targets in spinal muscular atrophy

Spinal muscular atrophy (SMA), a leading genetic cause of infant death, is a neurodegenerative disease characterized by the selective loss of particular groups of motor neurons (MNs) in the anterior horn of the spinal cord with progressive muscle wasting. SMA is caused by a deficiency of the survival motor neuron (SMN) protein due to a homozygous deletion or mutation of the SMN1 gene. However, the molecular mechanisms whereby the SMN complex regulates MN functions are not fully elucidated. Emerging studies on SMA pathogenesis have turned the attention of researchers to RNA metabolism, given that increasingly identified SMN-associated modifiers are involved in both coding and non-coding RNA (ncRNA) processing. Among various ncRNAs, microRNAs (miRNAs) are the most studied in terms of regulation of posttranscriptional gene expression. Recently, the discovery that miRNAs are critical to MN function and survival led to the study of dysregulated miRNAs in SMA pathogenesis. Circulating miRNAs have drawn attention as a readily available biomarker due to their property of being clinically detectable in numerous human biofluids through non-invasive approaches. As there are recent promising findings from novel miRNA-based medicines, this article presents an extensive review of the most up-to-date studies connecting specific miRNAs to SMA pathogenesis and the potential applications of miRNAs as biomarkers and therapeutic targets for SMA.

Cognitive Performance of Patients with Adult 5q-Spinal Muscular Atrophy and with Amyotrophic Lateral Sclerosis

Motor neuron diseases, such as spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS), share several clinical similarities while differing substantially in etiology, disease onset and progression. Cognitive dysfunction, a clinically relevant non-motor feature in a substantial proportion of ALS patients, has been less frequently investigated in SMA. In this prospective multicenter cross-sectional study, cognitive function was assessed by the Edinburgh Cognitive (and Behavioural) ALS Screen (ECAS) and a German vocabulary test (Wortschatztest, WST) in 34 adult patients with SMA types 2-4 and in 34 patients with ALS. Demographic and clinical parameters were assessed to identify factors that potentially influence cognitive function. While SMA and ALS patients were comparable in the vocabulary test, on average, SMA patients performed better than ALS patients in the cognitive domains of memory, language and executive function. Better cognitive abilities in SMA patients seemed to be related to the early onset, rather than the extent or the duration, of their physical handicap. Future studies should focus on disease-specific cognitive functions in SMA.

Metabolic and Nutritional Issues Associated with Spinal Muscular Atrophy

Spinal muscular atrophy (SMA), the main genetic cause of infant death, is a neurodegenerative disease characterized by the selective loss of motor neurons in the anterior horn of the spinal cord, accompanied by muscle wasting. Pathomechanically, SMA is caused by low levels of the survival motor neuron protein (SMN) resulting from the loss of the SMN1 gene. However, emerging research extends the pathogenic effect of SMN deficiency beyond motor neurons. A variety of metabolic abnormalities, especially altered fatty acid metabolism and impaired glucose tolerance, has been described in isolated cases of SMA; therefore, the impact of SMN deficiency in metabolic abnormalities has been speculated. Although the life expectancy of these patients has increased due to novel disease-modifying therapies and standardization of care, understanding of the involvement of metabolism and nutrition in SMA is still limited. Optimal nutrition support and metabolic monitoring are essential for patients with SMA, and a comprehensive nutritional assessment can guide personalized nutritional therapy for this vulnerable population. It has recently been suggested that metabolomics studies before and after the onset of SMA in patients can provide valuable information about the direct or indirect effects of SMN deficiency on metabolic abnormalities. Furthermore, identifying and quantifying the specific metabolites in SMA patients may serve as an authentic biomarker or therapeutic target for SMA. Here, we review the main epidemiological and mechanistic findings that link metabolic changes to SMA and further discuss the principles of metabolomics as a novel approach to seek biomarkers and therapeutic insights in SMA.

Cost-Effectiveness of Nusinersen and Universal Newborn Screening for Spinal Muscular Atrophy

OBJECTIVE

To evaluate the cost-effectiveness of nusinersen with and without universal newborn screening for infantile-onset spinal muscular atrophy (SMA).

STUDY DESIGN

A Markov model using data from clinical trials with US epidemiologic and cost data was developed. The primary interventions studied were nusinersen treatment in a screening setting, nusinersen treatment in a nonscreening setting, and standard care. Analysis was conducted from a societal perspective.

RESULTS

Compared with no screening and no treatment, the incremental cost-effectiveness ratio (ICER) for nusinersen with screening was $330 558 per event-free life year (LY) saved, whereas the ICER for nusinersen treatment without screening was $508 481 per event-free LY saved. For nusinersen with screening to be cost-effective at a willingness-to-pay (WTP) threshold of $50 000 per event-free LY saved, the price would need to be $23 361 per dose, less than one-fifth its current price of $125 000. Preliminary data from the NURTURE trial indicated an 85.7% improvement in expected LYs saved compared with our base results. In probabilistic sensitivity analysis, nusinersen and screening was a preferred strategy 93% of the time at a $500 000 WTP threshold.

CONCLUSION

Universal newborn screening for SMA provides improved economic value for payers and patients when nusinersen is available.

Generalized Hypotonia Revealing Spinal Muscular Atrophy Type 2: The First Case Reported From the Dominican Republic and a Review of the Literature

Spinal muscular atrophy (SMA) is a rare, inherited autosomal recessive disease. Histopathological shreds of evidence related to the condition have suggested degenerative changes at the level of the spinal cord and brain stem. Deletions or mutations in the survival motor neuron 1 (SMN1) gene are the underlying cause of this disease. It is characterized by hypotonia, muscular atrophy, areflexia, fasciculations, and flaccid paralysis. It is further classified into five variants, depending upon the patient's age and clinical features.

In this report, we present a rare case of SMA type 2 in a one-year-old female infant who presented with generalized hypotonia and axial body weakness. Besides clinical evaluation, her genetic analysis confirmed that she had a deletion of one of the SMN1 genes. Hence, the diagnosis of SMA type 2 was confirmed.

Our study aims to emphasize that clinicians must consider this rare entity whenever a patient presents with the signs and symptoms mentioned above. As the most common cause of death in this disease is respiratory depression, an early diagnosis would prevent complications and help in the parents' genetic counseling.

Current and emerging therapies for Duchenne muscular dystrophy and spinal muscular atrophy

Many neuromuscular diseases are genetically inherited or caused by mutations in motor function proteins. Two of the most prevalent neuromuscular diseases are Duchenne Muscular Dystrophy (DMD) and Spinal Muscular Atrophy (SMA), which are often diagnosed during the early years of life, contributing to life-long debilitation and shorter longevity. DMD is caused by mutations in the dystrophin gene resulting in critical muscle wasting, with cardiac or respiratory failure by age 30. Lack of dystrophin protein is the leading cause of degeneration of skeletal and cardiac muscle. Corticosteroids and artificial respirators remain as the gold-standard management of complications and have significantly extended the life span of these patients. Additionally, drug therapies including eteplirsen (EXONDYS 51®), golodirsen (VYONDYS 53™), and viltolarsen (VILTEPSO®) have been approved by the FDA to treat specific types of DMD. SMA is defined by the degeneration of the anterior horn cells in the spinal cord and destruction of motor neuron nuclei in the lower brain-stem caused by SMN1 gene deletion. Loss of SMN1 protein is partly compensated by SMN2 protein synthesis with disease severity being affected by the success of SMN2 gene synthesis. Evidence-based recommendations for SMA are directed towards supportive therapy and providing adequate nutrition and respiratory assistance as needed. Treatment and prevention of complications of muscle weakness are crucial for reducing the phenotype expression of SMA. Furthermore, drug therapies including injectables such as onasemnogene abeparvovec-xioi (ZOLGENSMA®), nusinersen (SPINRAZA®), and an oral-solution, risdiplam (EVRYSDI™), are medications that have been FDA-approved for the treatment of SMA. This review discusses the current and emerging therapeutic options for patients with DMD and SMA.

Respiratory Trajectories in Type 2 and 3 Spinal Muscular Atrophy in the iSMAC Cohort Study

Objective

To describe the respiratory trajectories and their correlation with motor function in an international pediatric cohort of patients with type 2 and nonambulant type 3 spinal muscular atrophy (SMA).

Methods

This was an 8-year retrospective observational study of patients in the International SMA Consortium (iSMAc) natural history study. We retrieved anthropometrics, forced vital capacity (FVC) absolute, FVC percent predicted (FVC%P), and noninvasive ventilation (NIV) requirement. Hammersmith Functional Motor Scale (HFMS) and revised Performance of Upper Limb (RULM) scores were correlated with respiratory function. We excluded patients in interventional clinical trials and on nusinersen commercial therapy.

Results

There were 437 patients with SMA: 348 with type 2 and 89 with nonambulant type 3. Mean age at first visit was 6.9 (±4.4) and 11.1 (±4) years. In SMA type 2, FVC%P declined by 4.2%/y from 5 to 13 years, followed by a slower decline (1.0%/y). In type 3, FVC%P declined by 6.3%/y between 8 and 13 years, followed by a slower decline (0.9%/y). Thirty-nine percent with SMA type 2% and 9% with type 3 required NIV at a median age 5.0 (1.8–16.6) and 15.1 (13.8–16.3) years. Eighty-four percent with SMA type 2% and 80% with type 3 had scoliosis; 54% and 46% required surgery, which did not significantly affect respiratory decline. FVC%P positively correlated with HFMS and RULM scores in both subtypes.

Conclusions

In SMA type 2 and nonambulant type 3, lung function declines differently, with a common leveling after age 13 years. Lung and motor function correlated in both subtypes. Our data further define the milder SMA phenotypes and provide information to benchmark the long-term efficacy of new treatments for SMA.

Spinal Muscular Atrophy (SMA) Subtype Concordance in Siblings: Findings From the Cure SMA Cohort

Background:

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by homozygous survival of motor neuron 1 (SMN1) gene disruption. Despite a genetic etiology, little is known about subtype concordance among siblings.

Objective:

To investigate subtype concordance among siblings with SMA.

Methods:

Cure SMA maintains a database of newly diagnosed patients with SMA, which was utilized for this research.

Results:

Among 303 sibships identified between 1996 and 2016, 84.8% were subtype concordant. Of concordant sibships, subtype distribution was as follows: Type I, 54.5%; Type II, 31.9%; Type III, 13.2%; Type IV, 0.4%. Subtype and concordance/discordance association was significant (Fisher’s exact test; p < 0.0001). Among discordant sibships (chi-square test, p < 0.0001), Types II/III (52.2%) and Types I/II (28.3%) were the most common pairs. No association was found between sibling sex and concordance. Our findings show that most siblings with SMA shared the same subtype concordance (most commonly Type I).

Conclusions:

These data are valuable for understanding familial occurrence of SMA subtypes, enabling better individual treatment and management planning in view of new treatment options and newborn screening initiatives.

Quantitative description of upper extremity function and activity of people with spinal muscular atrophy

BACKGROUND

Therapeutic management of the upper extremity (UE) function of people with spinal muscular atrophy (SMA) requires sensitive and objective assessment. Therefore, we aimed to measure physiologic UE function of SMA patients with different functional abilities and evaluate the relation between these physiologic measures and functional UE scales.

METHODS

12 male and 5 female SMA patients (mean age 42 years; range 6-62 years) participated in this explorative study. Concerning the physiologic level, the maximal muscle torque, the maximal and normalized surface electromyography (sEMG) amplitudes, and the maximal passive and active joint angles were measured. Concerning the activity level, the Performance of the Upper Limb (PUL) scale was used, and hand function was examined using the Nine-Hole Peg Test and the Timed Test of In-Hand Manipulation (TIHM).

RESULTS

Outcome measures that significantly related to the functional ability were: the PUL score (all dimensions); the finger to palm task of the Timed TIHM; biceps, triceps, and forearm extensor strength; and the active range of motion of shoulder abduction, shoulder flexion, and wrist extension. In addition, the following physiologic variables were related to the activity level (PUL score): hand function (the Nine-Hole Peg Test; Rs = - 0.61), the Timed TIHM (Rs = - 0.53), the maximal muscle torque (Rs = 0.74), the maximal sEMG amplitude (Rs = 0.79), and the maximal active joint angle (Rs = 0.88).

CONCLUSIONS

Muscle functions in SMA patients are already affected before activity limitations are noticeable. Consequently, monitoring the maximal muscle strength and the normalized muscle activity during task performance could play a role in the early detection of UE limitations. The mechanism behind the loss of arm activities due to SMA is primarily caused by decreasing muscle capacity, which influences the ability to move an arm actively. In clinical practices, these dimensions should be considered separately when monitoring disease progression in order to better evaluate the need for interventions.

Spinal Muscular Atrophy in Blonde D'Aquitaine Calves Is Not Associated With FVT1 Gene Mutation

Spinal muscular atrophy (SMA) is a motor neuron disease (MND) in humans and diverse animal species: canid, felid, and bovid. To date, bovine SMA has been reported in Brown Swiss, Holstein, Friesian, and Red Danish breed; it has been associated with a genetic mutation of the FVT1 gene, also known as 3-ketodihydrosphingosine reductase (KDSR). The aim of the present case series was to describe clinical presentation, pathological findings, and genetic analysis of five Blond d'Aquitaine calves diagnosed with SMA and to determine whether the mutation was associated with the disease. Five Blonde d'Aquitaine calves (three females and two males) from the same cow-calf operation farm were presented between June 2018 and February 2019 because unable to stand or walk unassisted since birth. Neurological examination aroused suspicion of a diffuse lesion affecting the peripheral nervous system in all calves. Findings from electromyographic investigations and muscle and nerve biopsies were consistent with a non-regenerative, chronic, active axonal neuropathy and marked neurogenic muscular atrophy and assumed to be associated with a neurodegenerative process. Histopathological examination of tissue samples from two animals revealed neuronal loss and several degenerated, shrunken, and hypereosinophilic neurons at the level of the ventral horn of the cervico-thoracic and the lumbo-sacral intumescence, diffuse loss of myelinated axons at the level of the ventral funiculi of all segments of the spinal cord, and moderate diffuse astrocytic reaction. These findings confirmed the diagnosis of SMA. No mutation of the FVT1 gene was found on genetic analysis. Further study into the causative gene mutation of SMA in Blonde D'Aquitaine calves is under way. Identification of a novel genetic mutation could improve our understanding of the disease in human medicine.

Mutation analysis of 419 family and prenatal diagnosis of 339 cases of spinal muscular atrophy in China

Background

Spinal muscular atrophy (SMA) is a common and lethal autosomal recessive neurodegenerative disease caused by mutations in the survival motor neuron 1 (SMN1) gene. At present, gene therapy medicine for SMA, i.e., Spinraza (Nusinersen), has been approved by the FDA, bringing hope to SMA patients and families. Accurate diagnosis is essential for treatment. Our goal was to detect genetic mutations in SMA patients in China and to show the results of the prenatal diagnosis of SMA.

Methods

In this study, we examined 419 patients in our hospital from January 2010 to September 2019. Multiplex ligation-dependent probe amplification analysis was used to determine the copy numbers of SMN1 and SMN2. Long-range PCR combined with nested PCR was used to detect point mutations in SMN1. In addition to the above detection methods, we also used QF-PCR in prenatal diagnosis to reduce the impact of maternal contamination. We conducted a total of 339 prenatal diagnoses from January 2010 to September 2019.

Results

Homozygous deletion of SMN1 exon 7 was detected in 96.40% (404/419) of patients. Homozygous deletion of SMN1 exon 7 alone was detected in 15 patients (3.60%). In total, 10 point mutations were detected in the 15 pedigrees. Most patients with SMA Type I have 1 ~ 2 copies of the SMN2 gene. Patients with SMA Type II have 2 or 3 copies of the SMN2 gene. The results of prenatal diagnoses showed that 118 fetuses were normal, 149 fetuses were carriers of heterozygous variants, and the remaining 72 fetuses harbored compound heterozygous variants or homozygous variants.

Conclusions

Our study found that the most common mutation in SMA was homozygous deletion of SMN1 exon 7 in our study. We suggest that detecting only the deletion of exon 7 of SMN1 can meet most of the screening needs. We also believe that SMN2 copy numbers can help infer the disease classification and provide some reference for future treatment options.

Curcumin and neurological diseases

Objectives: The beneficial effects of many substances have been discovered because of regular dietary consumption. This is also the case with curcumin, whose effects have been known for more than 4,000 years in Eastern countries such as China and India. A curcumin-rich diet has been known to counteract many human diseases, including cancer and diabetes, and has been shown to reduce inflammation. The effect of a curcumin treatment for neurological diseases, such as spinal muscular atrophy; Alzheimer's disease; Parkinson's disease; amyotrophic lateral sclerosis; multiple sclerosis; and others, has only recently been brought to the attention of researchers and the wider population.Methods: In this paper, we summarise the studies on this natural product, from its isolation two centuries ago to its characterisation a century later.Results: We describe its role in the treatment of neurological diseases, including its cellular and common molecular mechanisms, and we report on the clinical trials of curcumin with healthy people and patients.Discussion: Commenting on the different approaches adopted by the efforts made to increase its bioavailability.

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.

The International Classification of Functioning, Disability and Health-Children and Youth as a framework for the management of spinal muscular atrophy in the era of gene therapy: a proof-of-concept study

BACKGROUND

Management of spinal muscular atrophy (SMA) has progressed enormously and reached unprecedented levels with nusinersen gene therapy. We are finally able to counter the progression of this devastating genetic disease, contributing to the definition of new trajectories in its natural history and the identification of new SMA phenotypes post-gene therapy. The aim of this paper was to use the The International Classification of Functioning, Disability and Health-Children and Youth as a framework for the management of spinal muscular atrophy in the era of gene therapy: a proof-of-concept study (ICF-CY) as a comprehensive documentation tool to better understand and improve care provided to a child with SMA and to illustrate its use in a multidisciplinary perspective with a proof-of-concept study.

CASE REPORT

An SMA child under gene therapy receiving a rehabilitation program. Clinical and functional outcome measures assessed at all levels of the ICF-CY, including impairment by Hammersmith Infant Neurological Examination, activity by Hammersmith Functional Motor Scale and Functional Independence Measure for Children, and participation by Pediatric Quality of Life Inventory™ - PedsQL™ and Neuromuscular Module™ as well as by parent report. Treatment outcomes were assessed at two main time points: at T0: prior to administration of nusinersen, and T1: immediately before the first administration of maintenance doses, 6 months after the first administration of nusinersen. A significant clinical improvement was seen on all domains between T0 and T1. The patient improved especially in motor skills and motor disability severity. The HRQOL showed a substantial improvement, too. ICF-CY codes were used to document change in body functions or structures, performance of activities or participation in social roles both in terms of gradient and hierarchy of change. This proof-of-concept study is the first attempt to explore SMA in a comprehensive manner from the perspective of the ICF-CY using a selected set of codes. These codes define essential child dimensions that can make up an ICF-CY core set, as identified by a trained multidisciplinary team, to guide assessment, treatment and rehabilitation.

CLINICAL REHABILITATION IMPACT

Although limited to a single patient, this study makes nonetheless a strong point: we suggest using the ICF-CY as an essential tool in SMA management at a time when gene therapy with nusinersen is changing the phenotypes of activity and functioning in these children.