Onasemnogene abeparvovec for presymptomatic infants with two copies of SMN2 at risk for spinal muscular atrophy type 1: the Phase III SPR1NT trial

Cost-utility analysis of newborn screening for spinal muscular atrophy in Japan

AIMS

Spinal muscular atrophy (SMA) is a rare genetic disorder characterized by progressive muscle weakness, atrophy, respiratory failure, and in severe cases, infantile death. Early detection and treatment before symptom onset may substantially improve outcomes, allowing patients to achieve age-appropriate motor milestones and longer survival. We assessed the cost-utility of newborn screening (NBS) for SMA in Japan.

MATERIALS AND METHODS

A cost-utility model (decision tree and Markov model) compared lifetime health effects and costs between "NBS" for SMA (presymptomatic treatment) or "no NBS" (treatment initiated at symptom onset). Model inputs were sourced from literature, local data, and expert opinion. Sensitivity and scenario analyses were conducted to assess model robustness and data validity.

RESULTS

Based on the 1:10,000 SMA incidence, it was estimated that 43 newborns/year would have SMA, and a total of 39 patients with SMA would initiate presymptomatic treatment after NBS. An estimated 736 quality-adjusted life-years were gained per annual birth cohort with NBS. NBS for SMA was dominant compared with no NBS (i.e. less costly and more effective), with ¥8,856,960,096 reduced total costs with NBS versus no NBS (base-case). Sensitivity and scenario analyses supported cost effectiveness of NBS for SMA versus no NBS. A greater percentage of patients was estimated to enjoy longer survival and be without permanent assisted ventilation with NBS versus no NBS.

LIMITATIONS

Real-world observations may differ from single-arm clinical trial outcomes. It was assumed that patients with SMA identified via NBS were asymptomatic and would receive treatment prior to symptoms. Best supportive care was not considered, and Japan-specific variations in gene replacement therapy protocol were not fully reflected.

CONCLUSION

NBS for SMA allows for early identification of patients with SMA and treatment initiation before symptom onset, improving health outcomes and reducing total costs than without NBS.

Mechanisms of functional improvement behind nusinersen treatment in adult spinal muscular atrophy

Nusinersen treatment not only prevents neurological deterioration in presymptomatic or early symptomatic children with spinal muscular atrophy (SMA) but promotes functional improvement in the later plateau phase in adults with SMA, though the mechanisms for such functional improvement are not fully understood. We evaluated the motor behaviors and electrophysiological performance of 10 consecutive adult patients with SMA before and 2, 6, 10 months after nusinersen treatment. Adult SMA mice (Smn-/-SMN2+/+) were treated with nusinersen intracerebroventricularly for 2 months with analysis of the SMN transcripts and proteins expression, motor function, electrophysiology, and pathology of spinal cord and muscles. SMA patients showed motor function improvement in 10 months after nusinersen treatment with an increase in compound muscle action potential (CMAP) amplitude and motor unit number estimation (MUNE). Nusinersen augmented the expression of full-length SMN transcripts and proteins in SMA mice. SMA mice receiving nusinersen treatment showed a motor behavioral improvement with an increase in MUNE. Although nusinersen treatment partially prevented spinal motor neuron death, there was no obvious elevation in motor neuron density despite an increase in MUNE, indicating the reactivation of quiescent motor neurons. Nusinersen treatment not only eliminated progressive denervation at the neuromuscular junction (NMJ), but also promoted NMJ innervation, implying the existence of reinnervation. The functional improvements observed with nusinersen treatment in adults with SMA during the later plateau phase primarily result from two mechanisms: the revival of live but functionless motor neurons and the reinnervation of NMJs through axonal sprouting and the formation of new motor units.

Cost-Effectiveness of Newborn Screening for Spinal Muscular Atrophy in Australian Hospitals

INTRODUCTION

This analysis evaluated the cost-effectiveness of newborn screening (NBS) for spinal muscular atrophy (SMA) from the perspective of Australian state hospital payers.

METHODS

A cost-utility analysis consisting of a decision tree and Markov cohort designed to calculate the difference in costs and health outcomes between two scenarios: (1) disease-modifying treatment (DMT) for SMA after diagnosis through NBS, and (2) DMT for SMA after diagnosis as symptoms appear. A population of 295,906 newborns was modeled, based on the total number of live births in Australia in 2023. Inputs included screening parameters, epidemiology inputs, SMA natural history data and DMT parameters (nusinersen and onasemnogene abeparvovec), costs, and health-related quality of life parameters. Assumed participation in NBS was 100%. A one-way sensitivity analysis and probabilistic sensitivity analysis were conducted to examine the impact of parameter uncertainty.

RESULTS

There were 30 patients identified with SMA, of whom 25 patients would be eligible for presymptomatic treatment. NBS for SMA was dominant compared with no NBS for SMA. On a population level, NBS demonstrated a lifetime gain of 267 quality-adjusted life years (QALY) and incremental costs of -AUD$3,983,263 (i.e., cost savings). Every dollar invested in NBS would save hospitals $3.69. Deterministic and probabilistic sensitivity analyses demonstrated the robustness of the base-case results.

CONCLUSION

NBS for SMA was dominant compared with no NBS for SMA in Australia from a state and territory payer perspective. Universal implementation of NBS for SMA would support access equity, as well as early diagnosis and treatment in infants with SMA, potentially leading to improved outcomes.

Systematic review for economic evaluations on newborn screening for spinal muscular atrophy

ObjectiveEvaluate the quality and cost-effectiveness of economic evaluations of newborn screening (NBS) for Spinal Muscular Atrophy (SMA).MethodsA systematic review was conducted following Cochrane Handbook guidelines and PRISMA-S checklist. From 146 identified papers, 22 were screened for full-text, and 5 were included. Studies were evaluated for quality of reporting and transparency using the CHEERs and QHES checklists. Data was extracted to inform the review.ResultsFour economic evaluations on NBS for SMA with high reporting quality were identified. Each study employed a cost-utility analysis with similar model structures, using a decision tree for screening and a Markov model for treatment outcomes. They each compared NBS with treatment vs clinical diagnosis (no screening) with treatment. Although treatment protocols of each study varied due to differences in the strategies considered and availability of treatment. All studies included a societal perspective in their analysis and considered a lifetime horizon ranging from 30 months to 100 years. Early NBS with treatment was found to be more cost-effective than late treatment in all studies with ICER values ranging from £-117,541 to $714,000 per QALY. The wide range of ICER values are due to assumptions of long-term outcomes which are still largely unknown.ConclusionNBS with treatment was found to be cost-effective by all studies when compared to no NBS and late treatment. Although there is uncertainty around long term outcomes. Future research should focus on collecting long-term efficacy and safety data and evaluating the cost-effectiveness of pre-symptomatic treatment.

Intra-amniotic antisense oligonucleotide treatment improves phenotypes in preclinical models of spinal muscular atrophy

Neurological disorders with onset before or at birth are a leading cause of morbidity and mortality in infants and children. Prenatal treatment has the potential to reduce or prevent irreversible neuronal loss and facilitate normal neurodevelopment. We hypothesized that antisense oligonucleotides (ASOs) delivered to the amniotic fluid by intra-amniotic (IA) injection could safely distribute to the fetal central nervous system (CNS) and provide therapeutic benefit in the motor neuron disease spinal muscular atrophy (SMA), caused by mutations of the survival of motor neuron 1 gene (SMN1), leading to deficiency of SMN protein. Although the splice-switching ASO nusinersen ameliorates SMA when delivered postnatally, substantial deficits can remain in severely affected infants. Here, IA injection of ASOs into two mouse models of severe SMA increased SMN expression in the CNS. In SMAΔ7 mice, which manifest pathology in utero, prenatal treatment improved motor neuron numbers, motor axon development, motor behavioral tests, and survival when compared with those in mice treated postnatally (between P1 and P3). To assess the feasibility of prenatal treatment in a large-animal model, ASOs were delivered midgestation to fetal sheep by IA or intracranial injection. ASOs delivered by IA injection distributed to the spinal cord at therapeutic concentrations and to multiple peripheral tissues without evidence of substantial toxicity to the fetus or mother. These data demonstrated that IA delivery of ASOs holds potential as a minimally invasive approach for prenatal treatment of SMA and possibly other severe, early-onset neurological disorders.

Differential respiratory function response in paediatric spinal muscular atrophy types 2 and 3 treated with nusinersen over 3 years

AIM

To establish whether the initial positive effect of nusinersen (NUS) on respiratory outcomes in the first year of treatment was maintained in children with Spinal Muscular Atrophy (SMA) type 2 and to further define the effect on children with type 3 treated over 3 years.

METHODS

A prospective observational study of children with type 2 and 3 beginning NUS in Queensland, Australia between June 2018-December 2020 was undertaken. Investigations conducted included age-appropriate lung function and polysomnography. Lung function data for two-years preceding NUS initiation was retrospectively collected. Change in lung function/polysomnography was assessed using mixed effects linear regression.

RESULTS

24 of 30 children with type 2 and 3 SMA (14 males; 2.6-15.8) were included (type 2 n = 12; type 3 n = 12). No child had respiratory-related admissions during the period of study. For type 2, annual decline in FVC z-score pre-treatment was -0.75 (95 % CI: 1.14, -0.39, p < 0.001), and for the first 3 years on NUS was -0.20 ([95 % CI: 0.33, -0.06, p = 0.01] difference p = 0.008). For type 3 minimal change was seen: pre-NUS and post FVC z-scores -0.20 (95 % CI: 1.00, 0.61 p = 0.05) and -0.46 (95 % CI: 0.88, -0.04 p = 0.40) respectively (difference p = 0.46). Mean change in total apnoea-hypopnoea indices (total AHI) in type 2 tended to reduce -1.75 (95 % CI: 4.95-0.9, p = 0.24); type 3 appeared to remain stable (-0.39 [95 % CI: 1.1-0.33, p = 0.28). One child with type 2 ceased NIV due to normalisation of total AHI and gas exchange.

CONCLUSION

Nusinersen lung function (FVC-z-scores) stability seen in the first year was maintained over 3 years and the total AHI tended to improve in type 2, but the long-term effects in type 3 are less clear.

Newborn screening facilitates early theranostics and improved spinal muscular atrophy outcome: five-year real-world evidence from Taiwan

BACKGROUND

Recent findings indicate that infants with spinal muscular atrophy (SMA) treated early through newborn screening (NBS) have better outcomes. This study aimed to investigate the long-term outcomes of a 5-year SMA NBS program in Taiwan.

RESULTS

From September 2017 to August 2022, two NBS centers screened patients for SMN1 homozygous deletion using quantitative real-time polymerase chain reaction (RT-PCR) or the Sequenom MassARRAY platform and subsequently confirmed the findings using multiplex ligation-dependent probe amplification (MLPA). Implementation of SMA NBS using RT-PCR or MassARRAY platform efficiently led to the detection of neonates with homozygous survival motor neuron 1 (SMN1) deletions at a median age of 9 (range 4-14) days. Among the 446,966 newborns screened, 22 were detected to have a homozygous deletion of SMN1, followed by MLPA confirmation. One patient initially showed negative screening results but was later confirmed to have a compound heterozygous mutation. Among the 23 confirmed cases, 8 patients had two SMN2 copies (all classified as SMA type 1), 11 patients had three SMN2 copies (including 4 with SMA type 1, 2 with SMA type 2, 3 with SMA type 3, and 2 asymptomatic cases), and 4 patients had four SMN2 copies (all asymptomatic). The mean (median) follow-up duration for 19 survivors was 4.2 (5.0) years. All patients with two SMN2 copies developed symptoms within 62 days; those with three SMN2 copies experienced disease onset within 1 year. After diagnosis, most patients were on a watch and wait to receive disease-modifying therapy (DMT) due to initial lack of insurance coverage and limitations on indications after coverage was granted. Of the 19 children who received DMT, the outcomes included 12 walkers, 1 walker requiring support, 3 sitters, 1 non-sitter, and 2 patients with SMA type 1b with two SMN2 copies who succumbed to acute respiratory failure.

CONCLUSIONS

This 5-year SMA NBS study using RT-PCR or the MassARRAY platform, along with an extended follow-up, demonstrates that early diagnosis and prompt treatment can enhance SMA clinical outcomes and change its natural progression in the therapeutic era. Infants with NBS who received presymptomatic DMT had better clinical outcomes than those who received symptomatic DMT.

Pushing the boundaries: future directions in the management of spinal muscular atrophy

Spinal muscular atrophy (SMA) is a devastating, degenerative, paediatric neuromuscular disease which until recently was untreatable. Discovery of the responsible gene 30 years ago heralded a new age of pioneering therapeutic developments. Three disease-modifying therapies (DMTs) have received regulatory approval and have transformed the disease, reducing disability and prolonging patient survival. These therapies - with distinct mechanisms, routes of administration, dosing schedules, side effect profiles, and financial costs - have dramatically altered the clinical phenotypes of this condition and have presented fresh challenges for patient care. In this review article we discuss potential strategies to maximise clinical outcomes through early diagnosis and treatment, optimised dosing, use of therapeutic combinations and state-of-the-art physiotherapy techniques, and the development of innovative therapies targeting alternative mechanisms.

Early life safety profiling of gene therapy for spinal muscular atrophy

The present study examines the safety profile of intravenous onasemnogene abeparvovec gene therapy in a real-world setting, both alone or in combination with intrathecal antisense oligonucleotide nusinersen therapy in two cohorts of patients with spinal muscular atrophy (SMA). The first cohort included eight presymptomatic infants treated solely with onasemnogene abeparvovec, while the second cohort comprised six symptomatic infants receiving onasemnogene abeparvovec and nusinersen co-therapy. All patients received the corticosteroid prednisolone coincident with gene therapy. Circulating alanine aminotransferase (ALT) and aspartate transaminase (AST) levels were measured to determine potential hepatoxicity, the primary focus of this study. Elevated ALT and AST levels were observed in one pre-symptomatic and three symptomatic patients post-treatment. However, all values returned to normal levels within 3 months of onasemnogene abeparvovec injection. Nusinersen treatment received previously or coincident with gene therapy did not impact the transient elevation of liver transaminases. This study highlights the importance of early intervention with molecular treatments for SMA and indicates that prior or coincident treatment with nusinersen is unlikely to impact safety of onasemnogene apoparvovec and could theoretically improve clinical outcomes in symptomatic infants or in those with gene therapy delayed beyond the immediate neonatal period.

Mortality of symptomatic children with spinal muscular atrophy in the era of disease-modifying therapies

With the availability of novel disease-modifying therapies (DMT), survival in spinal muscular atrophy (SMA) has significantly increased, but mortality is not rare in severely affected cases. To improve care further, we aimed to characterise causes of mortality in children with SMA over the last five years since the introduction of DMT. This was a retrospective review of all patients with SMA registered on SMA REACH UK database, who died between 2019 and 2023. In the last 5 years, 533 patients were registered with SMA REACH (6 pre-symptomatic; 1-SMA0; 247-SMA1; 188-SMA2; 91-SMA3). Twenty-five paediatric patients with SMA died in this period: 1 SMA0(4 %;1 copy-SMN2), 20 SMA1(80%;17 patients-2 copies of SMN2 and 1 with 3 copies of SMN2) and 4 SMA2(16%). In SMA 1 cohort, 7/20(35%) patients were treatment naïve (5 ineligible; 1 died prior to commencement; 1 declined). Twelve patients received nusinersen; median age at treatment initiation of 6 months (range:1 month-12.3 years old) and median treatment duration of 6 months (range:1 month-6.5 years). One patient switched from nusinersen to risdiplam at age 4 years (died 19 months later) and 1 received onasemnogene abeparvovec at 2 years old (died 10 months later). The median age of death was 10.5 months(range:8 weeks-13 years), and 80%(16/20) died from respiratory-related causes. In SMA 2 cohort, 2/4 patients were not eligible for DMT and one received risdiplam at age 13 years for duration of 2.7 years and died as result of traumatic brain injury. The median age of death was 18 years 4 months (range:16-21 years). Two deaths were respiratory-related and one of sudden cardiac arrest. In conclusion, over the last 5 years, 5% of SMA patients registered with SMA REACH died. The majority had symptomatic SMA1 with 2 SMN2 copies at the severe end of the spectrum and were either treatment naïve or had initiation of DMT after significant disease progression. Respiratory-related deaths occurred in 72% of known causes of death. Standard of care for respiratory management and ceiling of care discussions should continue to be a key part of the overall management particularly in those with severe disease at onset. These outcomes will be considerably improved once newborn screening will be available also in the UK.

Epidemiology of spinal muscular atrophy in Aotearoa-New Zealand

BACKGROUND

The advent of three effective disease modifying therapies for SMA has highlighted the need to understand the epidemiology of spinal muscular atrophy (SMA) and its disability impact.

OBJECTIVE

We aimed to establish the nationwide incidence and prevalence of SMA in Aotearoa-New Zealand, and to estimate the patients' disability and the impact of this on health resource utilisation.

METHODS

We used multiple sources to identify patients with SMA and verified the diagnosis, disabilities and resources utilisation by review of the individual patient notes and genetic results. The four year incidence period was from 1st July 2015 to 30th June 2019. Prevalence date was 1st March 2019. Of note, this time period pre-dated access to disease modifying therapy in New Zealand. Census data for 2018 was used for denominators. Descriptive statistics and capture-recapture were used to analyse the data. For context, we reviewed international SMA epidemiology.

RESULTS

The incidence per 100,000 live births was 8.0 (95% confidence interval (CI): 4.8-12.5). The standardised prevalence rate of SMA on 1st March 2019 was 1.78 per 100,000 (95% CI: 1.24, 2.33). Prevalence was significantly lower amongst Māori at 0.34 (95% CI: 0.08, 1.13; p = 0.006). Substantial decline from best motor milestone performance was seen; seven patients with SMA1 died without access to disease modifying therapy. 74% of the total cohort used wheelchairs. 23% required respiratory support. 62% had scoliosis, of whom 61% had had surgery. Surviving SMA1 patients had very high health service utilisation.

CONCLUSIONS

Incidence and prevalence figures match closely with international studies. This is the first record of low SMA rates in Māori. While the largest burden of disease falls on patients with SMA1 and 2 there is still substantial use of health resources among SMA3 and SMA4 patients.

Newborn screening and rapid genomic diagnosis of neuromuscular diseases

BackgroundIn recent years, treatments have been approved for certain neuromuscular diseases. In some cases, early pre-symptomatic treatment is necessary for optimal response, and thus newborn screening is critical.ObjectiveTo review the current status of newborn screening programs for neuromuscular diseases and early diagnosis through genetic testing.MethodsFollowing the PRISMA guidelines, a literature search was performed on PubMed for screening of neuromuscular diseases; the search was conducted on literature available as of 1 May 2024.ResultsIncluded were 77 articles on newborn screening for seven diseases: spinal muscular atrophy (19 studies), Duchenne muscular dystrophy (15), Pompe disease (20), X-linked adrenoleukodystrophy (14), Krabbe disease (6), metachromatic leukodystrophy (2), and myotonic dystrophy 1 (1). Ten articles on rapid genomic diagnosis were identified.ConclusionSince 2021, newborn screening programs for neuromuscular diseases have been established, notably in X-linked adrenoleukodystrophy, spinal muscular atrophy, Pompe disease, and Duchenne Muscular Dystrophy. Even in diseases where treatment is currently not life-changing, such as Krabbe disease, new newborn screening programs continue to be implemented, especially in the USA. The use of genetic diagnostic tests does not yet appear to be widespread or at least not widely reported. As new treatments become available, genomic newborn screening programs will need to be rapidly and broadly implemented.

Systematic literature review of the impact of spinal muscular atrophy therapies on bulbar function

BACKGROUND

Improvement and maintenance of bulbar function are important goals of disease-modifying treatments (DMTs) for spinal muscular atrophy (SMA), but standardized and validated measures for assessing bulbar function do not exist, nor does a widely accepted definition of bulbar function in SMA. As such, the impact of DMTs on bulbar function has not yet been comprehensively evaluated.

OBJECTIVE

We conducted a systematic literature review (SLR) to identify evidence about the impact of DMTs for SMA on bulbar function.

METHODS

We used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines to conduct this review. Embase® and MEDLINE® databases were searched through August 10, 2023. Eligible studies included patients with SMA who were treated with any DMT and reported bulbar function outcomes. Non-English studies were excluded.

RESULTS

We identified 51 studies (across 83 publications) that evaluated SMA DMTs and bulbar function for more than 1600 patients. The ability to feed orally, the ability to tolerate liquids, and the need for nutrition support were commonly reported. Most infants treated with any DMT before SMA symptom onset preserved bulbar function. Infants, children, and adults treated after SMA symptom onset experienced variable results in terms of bulbar function outcomes.

CONCLUSIONS

The definition and assessment of bulbar function are not standardized. Therefore, the tools, scales, methods, and timing used for bulbar function assessments varied among studies. Larger prospective studies using standardized and age-based assessments with longer follow-up periods are needed to assess the clinical stability of bulbar function for patients with SMA who receive DMTs.

What did we learn from new treatments in SMA? A narrative review

Spinal Muscular Atrophy (SMA) is a progressive neuromuscular disorder caused by SMN1 gene mutations, leading to inevitable motoneuronal degeneration. The introduction of disease modifying therapies has dramatically altered its natural history, shifting management from palliative to proactive approach. The new phenotypes and differences in treatment response and efficacy, are all contributing to reshape our understanding of the disease itself. This paper aims to analyze the lessons derived from the recent therapeutic advances, focusing on key aspects such as therapeutic windows, impact of early treatment and both disease progression and treatment efficacy modifiers. Ultimately, we also aim to give insights on new models of data analysis being explored to optimize patient trajectories and individualize treatment strategies.

Our experience and the overall review of clinical trials and real-world data confirm that early treatment maximizes motor outcomes, especially when started in the pre-clinical phase of the disease. The significant clinical improvements in symptomatic type I infants treated at different ages has provided evidence of an expanded 'therapeutic window', previously reported as limited to the first few months after birth on the basis of neurophysiological findings. The available data also provide evidence that function at baseline, SMN2 copy number, and age at treatment all appear to represent critical determinants of response. The availability of long-term data is increasingly used to pilot new predictive models to support clinical decision-making and to adapt therapeutic goals based on patient-specific variables.

Progress in AAV-Mediated In Vivo Gene Therapy and Its Applications in Central Nervous System Diseases

As the blood-brain barrier (BBB) prevents molecules from accessing the central nervous system (CNS), the traditional systemic delivery of chemical drugs limits the development of neurological drugs. However, in recent years, innovative therapeutic strategies have tried to bypass the restriction of traditional drug delivery methods. In vivo gene therapy refers to emerging biopharma vectors that carry the specific genes and target and infect specific tissues; these infected cells and tissues then undergo fundamental changes at the genetic level and produce therapeutic proteins or substances, thus providing therapeutic benefits. Clinical and preclinical trials mainly utilize adeno-associated viruses (AAVs), lentiviruses (LVs), and other viruses as gene vectors for disease investigation. Although LVs have a higher gene-carrying capacity, the vector of choice for many neurological diseases is the AAV vector due to its safety and long-term transgene expression in neurons. Here, we review the basic biology of AAVs and summarize some key issues in recombinant AAV (rAAV) engineering in gene therapy research; then, we summarize recent clinical trials using rAAV treatment for neurological diseases and provide translational perspectives and future challenges on target selection.

BCKDHA-BCKDHB digenic gene therapy restores metabolic homeostasis in two mouse models and a calf with classic maple syrup urine disease

Classic maple syrup urine disease (MSUD) results from biallelic mutations in genes that encode the branched-chain α-ketoacid dehydrogenase E1α (BCKDHA), E1β (BCKDHB), or dihydrolipoamide branched-chain transacylase (DBT) subunits, which interact to form the mitochondrial BCKDH complex that decarboxylates ketoacid derivatives of leucine, isoleucine, and valine. MSUD is an inborn error of metabolism characterized by recurrent life-threatening neurologic crises and progressive brain injury that can only be managed with an exacting prescription diet or allogeneic liver transplant. To develop a gene replacement therapy for MSUD, we designed a dual-function recombinant adeno-associated virus serotype 9 (rAAV9) vector to deliver codon-optimized BCKDHA and BCKDHB (rAAV9.hA-BiP-hB) to the liver, muscle, heart, and brain. rAAV9.hA-BiP-hB restored coexpression of BCKDHA and BCKDHB as well as BCKDH holoenzyme activity in BCKDHA-/- HEK293T cells and did not perturb physiologic branched-chain amino acid homeostasis in wild-type mice at a systemic dose of 2.7 × 1014 vector genomes per kilogram. In two models of severe MSUD (Bckdha-/- and Bckdhb-/- mice) and a newborn calf homozygous for BCKDHA c.248C>T, one postnatal injection prevented perinatal death, normalized growth, restored coordinated expression of BCKDHA and BCKDHB in the skeletal muscle, liver, heart, and brain, and stabilized MSUD biomarkers in the face of high protein ingestion. In summary, we developed a one-time BCKDHA-BCKDHB systemic dual-gene replacement strategy that holds promise as a therapeutic alternative to prescription diet and liver transplant for treatment of MSUD types 1A and 1B, the two most common forms of MSUD in humans.

Extracellular vesicles efficiently deliver survival motor neuron protein to cells in culture

Spinal Muscular Atrophy (SMA) is a genetic neuromuscular disorder caused by homozygous mutation or deletion of the survival motor neuron 1 (SMN1) gene, leading to a low quantity of SMN protein in cells. This depletion of SMN protein preferentially leads to death of motor neurons and, consequently, muscle atrophy, in addition to defects in many other peripheral tissues. SMN protein is naturally loaded into extracellular vesicles (EVs), which are sub-micron-sized, membrane-bound particles released from all cell types. The innate ability of EVs to deliver cargo to recipient cells has caused these vesicles to gain interest as therapeutic delivery vehicles. In this study, we show that adenovirus-mediated overexpression of SMN protein in HepG2 cells leads to the release of EVs loaded with high levels of SMN protein into conditioned medium. Application of this medium to recipient cells in tissue culture led to uptake of the SMN protein, which subsequently transited to the nucleus and co-localized with Gemin2 protein, forming nuclear gem-like structures similar to the native SMN protein. Overall, this work demonstrates that SMN protein can be delivered to cells through EVs, which holds promise as a potential therapy for patients with SMA.

Motor pool selectivity of neuromuscular degeneration in type I spinal muscular atrophy is conserved between human and mouse

Spinal muscular atrophy (SMA) is caused by low levels of the survival motor neuron (SMN) protein. Even though SMN is ubiquitously expressed, the disease selectively affects motor neurons, leading to progressive muscle weakness. Even among motor neurons, certain motor units appear more clinically resistant to SMA. To quantitatively survey selective resistance, we studied extensive neuromuscular autopsies of Type I SMA patients and age-matched controls. We found highly divergent degrees of degeneration of neighboring motor units, even within individual cranial nerves or a single anatomical area such as the neck. Examination of a Type I SMA patient maintained on life support for 17 years found that most muscles were atrophied, but the diaphragm was strikingly preserved. Nevertheless, some resistant human muscles with preserved morphology displayed nearly complete conversion to slow Type I myofibers. Remarkably, a similar pattern of selective resistance was observed in the SMNΔ7 mouse model. Overall, differential motor unit vulnerability in human Type I SMA suggests the existence of potent, motor unit-specific disease modifiers. Mechanisms that confer selective resistance to SMA may represent therapeutic targets independent of the SMN protein, particularly in patients with neuromuscular weakness refractory to current treatments.

Spinal Muscular Atrophy Update in Best Practices: Recommendations for Treatment Considerations

Background and Objectives

Spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by biallelic variants of the Survival Motor Neuron 1 gene (SMN1) that affects approximately 1 in 15,000 live births. Availability of 3 SMN-enhancing treatments for SMA has led to urgency to review how clinicians and patients use these treatments for SMA, while additional research and real-world data and experience are being collected. This work describes important factors to assist with decision-making for SMN-enhancing treatments.

Methods

A systematic literature review was conducted on SMN-enhancing treatments for SMA and related studies. A working group of American and European health care providers with expertise in SMA care identified barriers and developed recommendations through a modified Delphi technique with serial surveys and feedback through virtual meetings to fill gaps for information where evidence is limited. A community working group of an individual living with SMA and caregivers provided insight and perspective on SMA treatments and support through a virtual meeting to guide recommendations.

Results

The health care provider working group and the community working group agreed that when determining whether to start, change, add, or discontinue a treatment, essential considerations include patient and family/caregiver perspective, and treatment safety and side effects. When initiating treatment for patients newly diagnosed with SMA, important patient characteristics are age and Survival Motor Neuron 2 gene (SMN2) copy number. Furthermore, when initiating, changing, or adding treatment, current clinical status and comorbidities drive decision-making. When considering a medication or treatment plan change, unless there is an urgent indication, a treatment and associated patient outcomes should be monitored for a minimum of 6-12 months. When determining a treatment plan with an adolescent or adult with SMA, consider factors such as quality of life, burden vs benefit of treatment, and reproductive issues. Access to care coordination and interdisciplinary/multidisciplinary care are essential to treatment success.

Discussion

Sharing information about current knowledge of treatments and shared decision-making between health care providers and patients living with SMA and caregivers are essential to overcoming barriers to providing SMN-enhancing treatments.

Gene therapy for genetic diseases: challenges and future directions

Genetic diseases constitute the majority of rare human diseases, resulting from abnormalities in an individual's genetic composition. Traditional treatments offer limited relief for these challenging conditions. In contrast, the rapid advancement of gene therapy presents significant advantages by directly addressing the underlying causes of genetic diseases, thereby providing the potential for precision treatment and the possibility of curing these disorders. This review aims to delineate the mechanisms and outcomes of current gene therapy approaches in clinical applications across various genetic diseases affecting different body systems. Additionally, genetic muscular disorders will be examined as a case study to investigate innovative strategies of novel therapeutic approaches, including gene replacement, gene suppression, gene supplementation, and gene editing, along with their associated advantages and limitations at both clinical and preclinical levels. Finally, this review emphasizes the existing challenges of gene therapy, such as vector packaging limitations, immunotoxicity, therapy specificity, and the subcellular localization and immunogenicity of therapeutic cargos, while discussing potential optimization directions for future research. Achieving delivery specificity, as well as long-term effectiveness and safety, will be crucial for the future development of gene therapies targeting genetic diseases.

Safety and Efficacy of IV Onasemnogene Abeparvovec for Pediatric Patients With Spinal Muscular Atrophy: The Phase 3b SMART Study

BACKGROUND AND OBJECTIVES

Safety and efficacy of IV onasemnogene abeparvovec has been demonstrated for patients with spinal muscular atrophy (SMA) weighing <8.5 kg. SMART was the first clinical trial to evaluate onasemnogene abeparvovec for participants weighing 8.5-21 kg.

METHODS

SMART was an open-label, multicenter, phase 3b study conducted across 13 sites in 9 countries (NCT04851873). Symptomatic pediatric participants with SMA (any type; treatment-naïve or had discontinued prior treatment) were stratified into 3 weight cohorts (≥8.5-13, >13-17, and >17-21 kg), administered onasemnogene abeparvovec, and followed for 52 weeks. Corticosteroids were initiated 24 hours before infusion with dose increases in response to adverse events (AEs) and subsequent tapering at investigator discretion. The primary objective was safety. Secondary objective was efficacy (motor function/motor milestones).

RESULTS

Twenty-four participants were enrolled; the majority had SMA type 2 (n = 11), 3 SMN2 copies (n = 18), and prior treatment (n = 21). All participants completed the study; no deaths occurred. All participants had ≥1 treatment-related AE(s), 7 of 24 (29%) had serious treatment-related AEs, and 23 of 24 (96%) had ≥1 AE of special interest. Twenty of 24 participants (83%) had asymptomatic hepatotoxicity events, which were primarily transaminase elevations. No participant had bilirubin elevations >2× upper limit of normal, developed symptomatic hepatotoxicity, or met Hy law criteria. Transient asymptomatic thrombocytopenia events were reported in 17 of 24 participants (71%); all resolved spontaneously with no related bleeding events reported. Three of 24 participants (13%) had cardiac AEs (all unrelated to treatment). No thrombotic microangiopathy or dorsal root ganglionopathy-related AEs were reported. AE frequency and severity were similar across weight groups, although corticosteroid exposure was greater for the 2 heavier cohorts (median 135.0, 201.0, and 194.0 days, respectively) with 37% and 33% still on corticosteroids at the study end. By week 52, most participants maintained or improved motor function (Hammersmith Functional Motor Scale-Expanded 16/18; Revised Upper Limb Module 15/17); 4 participants (all 3 SMN2 copies) achieved new motor milestones.

DISCUSSION

Onasemnogene abeparvovec safety profile was similar across weight groups in this heterogenous participant population. Frequency and duration of asymptomatic aminotransferase elevations and thrombocytopenia are notable findings. Most participants demonstrated maintenance or improvement of motor function, suggesting clinical benefit for patients with SMA weighing up to 21 kg.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov identifier (NCT04851873, clinicaltrials.gov/study/NCT04851873) submitted April 19, 2021. First participant enrolled on September 8, 2021.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that intravenous onasemnogene abeparvovec is safe in pediatric patients with SMA who weigh 8.5-21 kg.

Catecholaminergic dysfunction drives postural and locomotor deficits in a mouse model of spinal muscular atrophy

Development and maintenance of posture is essential behavior for overground mammalian locomotion. Dopamine and noradrenaline strongly influence locomotion, and their dysregulation initiates the development of motor impairments linked to neurodegenerative disease. However, the precise cellular and circuit mechanisms are not well defined. Here, we investigated the role of catecholaminergic neuromodulation in a mouse model of spinal muscular atrophy (SMA). SMA is characterized by severe motor dysfunction and postural deficits. We identify progressive loss of catecholaminergic synapses from spinal neurons that occur via non-cell autonomous mechanisms. Importantly, the selective restoration of survival motor neuron (SMN) in either catecholaminergic or serotonergic neurons is sufficient to correct impairments in locomotion. However, only combined SMN restoration in both catecholaminergic and serotonergic neurons or pharmacological treatment with l-dopa improve the severe postural deficits. These findings uncover the synaptic and cellular mechanisms responsible for the postural and motor symptoms in SMA and identify catecholaminergic neuromodulation as a potential therapeutic target.

Spinal muscular atrophy type 1 in the Caribbean: the first case report from the Dominican Republic

Spinal muscular atrophy (SMA) is a progressive genetic neuromuscular condition affecting spinal motor neurons. The underlying cause of SMA is deletions or mutations in the SMN gene. It is classified into five variants based on age and clinical manifestations of the patient. In this report, we present the case discovery of a four-month-old male patient with SMA type 1, presenting with generalized hypotonia and regression of acquired neurodevelopmental milestones. Our study aims to illustrate, through a case report, the clinical analysis, therapeutic interventions, and progression until the patient's demise. This aims to share the challenges in managing such patients and the strategies employed in their care plan. By documenting this case, our goal is to contribute to the understanding of SMA type 1 and emphasize the ongoing need for learning effective care strategies.

Comprehensive analysis of adverse events associated with onasemnogene abeparvovec (Zolgensma) in spinal muscular atrophy patients: insights from FAERS database

Onasemnogene Abeparvovec (Zolgensma) is a gene therapy for the treatment of Spinal Muscular Atrophy (SMA) with improved motor neuron function and the potential for a singular treatment. Information on its adverse drug reactions is mainly from clinical trials and real-world studies with extensive sample sizes are lacking. In this study, we analyzed the U.S. Food and Drug Administration's Adverse Event Reporting System (FAERS) database to assess the drug safety profile of Zolgensma. A total of 1951 adverse event reports associated with onasemnogene abeparvovec (Zolgensma), containing 778 import important medical event (IME) signals, were identified from the FAERS database, and multiple disproportionate analysis algorithms were used to determine the significance of these adverse events. This study identified 281 onasemnogene abeparvovec-related adverse events (AEs), including some significant adverse events not mentioned in the product labelling. Elevated liver enzymes, fever, vomiting, and thrombocytopenia were the most common adverse reactions. Most adverse events manifested within the initial month of onasemnogene abeparvovec use, especially the first 8 days, but some may still occur after 1 year of treatment. Sex-specific scrutiny revealed differing risk levels for adverse events among women and men. Thrombocytopenia and thrombotic microangiopathy are more common in patients weighing ≥8.5 kg, and changes in renal function need to be closely monitored if thrombotic microangiopathy occurs. The above findings provide valuable insights into optimizing the utilization of onasemnogene abeparvovec, improving its effectiveness, and minimizing potential side effects, thereby greatly facilitating its practical application in clinical settings.

Challenges in Cardiomyopathy Gene Therapy Clinical Trial Design

Gene therapy has emerged as a possible treatment for progressive, debilitating Mendelian cardiomyopathies with limited therapeutic options. This paper arises from discussions at the 2023 Cardiovascular Clinical Trialists Forum and highlights several challenges relevant to gene therapy clinical trials, including low prevalence and high phenotypic heterogeneity of Mendelian cardiomyopathies, outcome selection complexities and resulting regulatory uncertainty, and immune responses to the adeno-associated viral vectors that are being used in ongoing studies. Avenues to address these challenges such as natural history studies, external controls, novel regulatory pathways, and immunosuppression are discussed. Relevant cases of recent therapy approvals are highlighted. Ultimately, this work aims to broadly frame discussions on and provide potential future avenues for clinical trial design for rare cardiomyopathy gene therapies.

Advances in Disease-Modifying Therapeutics for Chronic Neuromuscular Disorders

Neuromuscular disorders can cause respiratory impairment by affecting the muscle fibers, neuromuscular junction, or innervation of respiratory muscles, leading to significant morbidity and mortality. Over the past few years, new disease-modifying therapies have been developed and made available for treating different neuromuscular disorders. Some of these therapies have remarkable effectiveness, resulting in the prevention and reduction of respiratory complications. For myasthenia gravis (MG), efgartigimod, ravulizumab, rozanolixizumab, and zilucoplan have been Food and Drug Administration (FDA)-approved for the treatment of acetylcholine receptor (AChR) antibody-positive generalized MG in the past 2 years. Rozanolixiumab is also approved for treating MG caused by muscle-specific tyrosine kinase (MuSK) antibodies. The new MG therapeutics target the complement system or block the neonatal fragment crystallizable (Fc) receptors (FcRn), leading to significant clinical improvement. For spinal muscular atrophy (SMA), nusinersen (intrathecal route) and risdiplam (oral route) modify the splicing of the SMN2 gene, increasing the production of normal survival motor neuron (SMN) protein. Onasemnogene abeparvovec is a gene replacement therapy that encodes a functional SMN protein. All SMA medications, particularly onasemnogene abeparvovec, have led to clinically meaningful improvement. For late-onset Pompe disease (LOPD), avalglucosidase alfa has shown a greater improvement in respiratory function, ambulation, and functional outcomes in comparison to alglucosidase alfa, and cipaglucosidase alfa combined with miglustat has shown improvement in respiratory and motor function in a cohort of enzyme replacement therapy-experienced LOPD patients. Amyotrophic lateral sclerosis (ALS) remains a challenge. The two most recent FDA-approved medications, namely sodium phenylbutyrate and tofersen, may slow down the disease by a few months in a selected population but do not stop the progression of the disease.

Adeno-associated virus serotype 9 antibodies in neonates and young children: Seroprevalence and kinetics

Gene therapies such as onasemnogene abeparvovec for spinal muscular atrophy (SMA) utilize adeno-associated virus 9 (AAV9) for targeted gene delivery, which requires an AAV9 antibody (AAV9-Ab) immunoglobulin G (IgG) ≤1:50 titer threshold. This retrospective cohort study evaluated age-related AAV9-Ab IgG seroprevalence for patients with SMA (part 1) and AAV9-Ab IgG kinetics and time to 1:50 titer threshold in newborns with elevated AAV9-Ab IgG titers (≥1:100) (part 2). A semi-quantitative ELISA assay was used in part 1 (N = 1,323 patients). For patients aged <12 months, 3.9% (n/N = 31/795) had elevated AAV9-Ab IgG titers (≥1:100); prevalence declined with age. In part 2, a new quantitative ELISA (linear mixed effects model) described continuous AAV9-Ab IgG concentrations for patients with initial titers ≥1:100. AAV9-Ab IgG concentrations waned according to first-order kinetics (58 samples; N = 18 patients). The model-based estimation of the AAV9-Ab IgG average half-life was 41 (95% CI, 38-44) days. Based on visualization, 200 ELISA units/mL was a reasonable approximate for the 1:50 titer threshold. In conclusion, initially elevated titers ≥1:100 in newborn patients declined with age. The new quantitative ELISA may allow for quantification of time to threshold for AAV9-Ab IgG retesting for onasemnogene abeparvovec treatment, leading to treatment as early as possible for patients with SMA.

Patient-specific responses to SMN2 splice-modifying treatments in spinal muscular atrophy fibroblasts

The availability of three therapies for the neuromuscular disease spinal muscular atrophy (SMA) highlights the need to match patients to the optimal treatment. Two of these treatments (nusinersen and risdiplam) target splicing of SMN2, but treatment outcomes vary from patient to patient. An incomplete understanding of the complex interactions among SMA genetics, SMN protein and mRNA levels, and gene-targeting treatments, limits our ability to explain this variability and identify optimal treatment strategies for individual patients. To address this, we analyzed responses to nusinersen and risdiplam in 45 primary fibroblast cell lines. Pre-treatment SMN2-FL, SMN2Δ7 mRNA, and SMN protein levels were influenced by SMN2 copy number, age, and sex. After treatment, SMN and mRNA levels were more heterogeneous. In 43% of patients, response to both therapies was similar, but in 57% one treatment led to a significantly higher SMN increase than the other treatment. Younger age, higher SMN2 copy number, and higher SMN levels before treatment predicted better in vitro efficacy. These findings showcase patient-derived fibroblasts as a tool for identifying molecular predictors for personalized treatment.

Rare disease genomics and precision medicine

Rare diseases, though individually uncommon, collectively affect millions worldwide. Genomic technologies and big data analytics have revolutionized diagnosing and understanding these conditions. This review explores the role of genomics in rare disease research, the impact of large consortium initiatives, advancements in extensive data analysis, the integration of artificial intelligence (AI) and machine learning (ML), and the therapeutic implications in precision medicine. We also discuss the challenges of data sharing and privacy concerns, emphasizing the need for collaborative efforts and secure data practices to advance rare disease research.

Type I spinal muscular atrophy and disease modifying treatments: a nationwide study in children born since 2016

Background

The advent of disease-modifying treatments (DMT) has changed natural history in 5q Spinal muscular atrophy (SMA). The aim of this study was to report survival and functional aspects in all the Italian type I children born since 2016.

Methods

The study included all symptomatic children with type I SMA born since January 1st, 2016, when DMTs became available in Italy. All the Italian SMA referral centers provided data on survival and motor, respiratory, and nutritional status. To compare survival rate pre and post DMTs approval, we also included similar data from SMA I patients born between January 1st, 2010, and December 31st, 2015. A two-proportion z-test was conducted to compare the two cohorts. The significance level was set at p < .05.

Findings

241 infants (98%) had type I SMA. Mean follow-up was 3.48 years (SD 2.33). Among type I patients, 42/241 did not survive (25 untreated), while 199 were alive at last follow-up (all treated; mean treatment age 0.6 years), with 25 needing >16 h/day ventilation or tracheostomy with continuous invasive ventilation. 130 of the 199 survivors (65%) achieved independent sitting, and 175 (87.9%) did not require tube feeding.

Interpretation

Our study provides a picture of the 'new natural history' of type I SMA, confirming the impact of the new therapies on the progression of type I with longer survival r and has better motor, respiratory and nutritional.

Funding

This research was partially funded by grants from the Italian Ministry of Health.

Efficacy and safety of gene therapy with onasemnogene abeparvovec in children with spinal muscular atrophy in the D-A-CH-region: a population-based observational study

Background

Real-world data on gene addition therapy (GAT) with onasemnogene abeparvovec (OA), including all age groups and with or without symptoms of the disease before treatment are needed to provide families with evidence-based advice and realistic therapeutic goals. Aim of this study is therefore a population-based analysis of all patients with SMA treated with OA across Germany, Austria and Switzerland (D-A-CH).

Methods

This observational study included individuals with Spinal Muscular Atrophy (SMA) treated with OA in 29 specialized neuromuscular centers in the D-A-CH-region. A standardized data set including WHO gross motor milestones, SMA validated motor assessments, need for nutritional and respiratory support, and adverse events was collected using the SMArtCARE registry and the Swiss-Reg-NMD. Outcome data were analyzed using a prespecified statistical analysis plan including potential predictors such as age at GAT, SMN2 copy number, past treatment, and symptom status.

Findings

343 individuals with SMA (46% male, 54% female) with a mean age at OA of 14.0 months (range 0-90, IQR 20.0 months) were included in the analysis. 79 (23%) patients were clinically presymptomatic at the time of treatment. 172 (50%) patients received SMN2 splice-modifying drugs prior to GAT (risdiplam: n = 16, nusinersen: n = 154, both: n = 2). Functional motor improvement correlated with lower age at GAT, with the best motor outcome in those younger than 6 weeks, carrying 3 SMN2 copies, and being clinically presymptomatic at time of treatment. The likelihood of requiring ventilation or nutritional support showed a significantly increase with older age at the time of GAT and remained stable thereafter. Pre-treatment had no effect on disease trajectories. Liver-related adverse events occurred significantly less frequently up to 8 months of age. All other adverse events showed an even distribution across all age and weight groups.

Interpretation

Overall, motor, respiratory, and nutritional outcome were dependent on timing of GAT and initial symptom status. It was best in presymptomatic children treated within the first six weeks of life, but functional motor scores also increased significantly after treatment in all age groups up to 24 months. Additionally, OA was best tolerated when administered at a young age. Our study therefore highlights the need for SMA newborn screening and immediate treatment to achieve the best possible benefit-risk ratio.

Funding

The SMArtCARE and Swiss-Reg-NMD registries are funded by different sources (see acknowledgements).

Adeno-associated virus therapies: Pioneering solutions for human genetic diseases

Adeno-associated virus (AAV) has emerged as a fundamental component in the gene therapy landscape, widely acknowledged for its effectiveness in therapeutic gene delivery. The success of AAV-based therapies, such as Luxturna and Zolgensma, underscores their potential as a leading vector in gene therapy. This article provides an in-depth review of the development and mechanisms of AAV vector-based therapies, offering a comprehensive analysis of the latest clinical trial outcomes in central nervous system (CNS) diseases, ocular conditions, and hemophilia, where AAV therapies have shown promising results. Additionally, we discusse the selection of administration methods and serotypes tailored to specific diseases. Our objective is to showcase the innovative applications and future potential of AAV-based gene therapy, laying the groundwork for continued clinical advancements.

Gene-based therapy for the treatment of spinal muscular atrophy types 1 and 2 : a systematic review and meta-analysis

Despite numerous studies identifying the advantages of therapies for spinal muscular atrophy (SMA), healthcare professionals encounter obstacles in determining the most effective treatment. This study aimed to investigate the effects of gene-based therapy for SMA. A systematic search was conducted from inception to May 2024 across databases, and all studies assessing the effects of gene-based therapy on patients with SMA types 1 and 2 were included. The outcomes measured were survival, the need for ventilatory support, improvements in motor function, and the occurrence of adverse drug reactions. Meta-analyses were performed using a random-effects model. A total of 57 studies (n = 3418) were included, and the meta-analyses revealed that onasemnogene abeparvovec showed the highest survival rate (95% [95% CI: 88, 100]), followed by risdiplam (86% [95% CI: 76, 94]) and nusinersen (60% [95% CI: 50, 70]). The number of patients needing ventilatory support was reduced after treatment with onasemnogene abeparvovec (risk ratio = 0·10 [95% CI: 0·02, 0·53]). Onasemnogene abeparvovec and risdiplam had similar proportions of patients with improvements in the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders score of ≥4 points (92% [95% CI: 62, 100] vs 90% [95% CI: 77, 97]). In contrast, nusinersen had the smallest improvement (74% [95% CI: 66, 81]). The most frequently observed adverse drug reactions were headaches, vomiting, and gastrointestinal disorders. Gene-based therapy benefits patient survival and improves motor function. Onasemnogene abeparvovec and risdiplam appear highly effective, whereas nusinersen exhibits moderate effectiveness.

Advances and Challenges in Gene Therapy for Neurodegenerative Diseases: A Systematic Review

This review explores recent advancements in gene therapy as a potential treatment for neurodegenerative diseases, focusing on intervention mechanisms, administration routes, and associated limitations. Following the PRISMA procedure guidelines, we systematically analyzed studies published since 2020 using the PICO framework to derive reliable conclusions. The efficacy of various gene therapies was evaluated for Parkinson's disease (n = 12), spinal muscular atrophy (n = 8), Huntington's disease (n = 3), Alzheimer's disease (n = 3), and amyotrophic lateral sclerosis (n = 6). For each condition, we assessed the therapeutic approach, curative or disease-modifying potential, delivery methods, advantages, drawbacks, and side effects. Results indicate that gene therapies targeting specific genes are particularly effective in monogenic disorders, with promising clinical outcomes expected in the near future. In contrast, in polygenic diseases, therapies primarily aim to promote cell survival. A major challenge remains: the translation of animal model success to human clinical application. Additionally, while intracerebral delivery methods enhance therapeutic efficacy, they are highly invasive. Despite these hurdles, gene therapy represents a promising frontier in the treatment of neurodegenerative diseases, underscoring the need for continued research to refine and personalize treatments for each condition.

Nutrition outcomes of disease modifying therapies in spinal muscular atrophy: A systematic review

The nutritional implications of spinal muscular atrophy (SMA) are profound. Disease modifying therapies (DMT) have improved clinical outcomes. This review describes the impact of DMT on nutrition outcomes. A systematic search strategy was applied across seven databases until May 2023. Eligible studies measured nutrition outcomes in individuals with SMA on DMT (nusinersen, risdiplam or onasemnogene abeparvovec [OA]) compared to untreated comparators. Nutrition outcomes included anthropometry, feeding route, swallowing dysfunction, dietary intake, dietetic intervention, nutritional biochemistry, metabolism, gastrointestinal issues and energy expenditure. Articles retrieved were screened in duplicate, data were extracted and appraised systematically. Sixty three articles from 54 studies were included; 41% (n = 22) investigated nusinersen in pediatric participants with SMA type 1. Anthropometry (n = 18), feeding route (n = 39), and swallowing dysfunction (n = 18) were the most commonly reported outcomes. In combined pediatric and adult cohorts, BMI z-score remained stable post nusinersen therapy. The proportion of children with SMA requiring enteral nutrition was stable post nusinersen therapy. Ability to thrive at age 1.5 years was higher in children treated in early infancy with OA compared to historical controls. Significant heterogeneity existed across study population characteristics and outcome measures. Nusinersen may prevent deterioration in some nutrition outcomes; and OA in early infancy may be associated with improved nutrition outcomes. Timing of DMT initiation is an important consideration for future nutrition research. Studies investigating nutrition as a primary outcome of DMT, using consistent outcome measures are required for nutritional management strategies for this cohort to be appropriately tailored.

Prognostic factors for tube feeding in type I SMA patients treated with disease-modifying therapies: a cohort study

The aim of this study was to assess the need for tube feeding in a cohort of treated infants with type I SMA and to identify predictive factors. All patients were classified at baseline, when treatment started, and at follow-up according to their functional level and the need for tube feeding. Fisher's exact test was used to examine the associations between the outcome at the last follow-up and SMA type, SMN2 copy number, and baseline nutritional status. ANOVA was performed to compare CHOP INTEND scores and age at treatment initiation with outcomes. The cohort includes 75 type I SMA infants treated between 0.1 and 5 years of age. At the last follow-up, 34 had no need for tube feeding, 9 had tube feeding but were also able to be fed by mouth, and 32 had tube feeding and were unable to be fed by mouth. Thirty of the 41 infants with tube feeding at follow-up already had feeding difficulties when treatment was started. The need for tube feeding at follow-up was associated with the level of feeding involvement at baseline and with CHOP INTEND scores [p < 0.001] but not with SMN2 copy number, SMA type 1 subtypes or age at treatment. The results of this study suggest that the need for tube feeding is not frequent in treated infants with type I SMA and, when occurring, can be predicted by the level of feeding involvement and low CHOP INTEND scores at baseline. What is Known: • The advent of disease-modifying therapies is increasingly changing the approach to swallowing and nutritional management in type I SMA. • Clinical trials and real-world data using all three disease-modifying therapies report a rather wide variability of feeding outcome and need for tube feeding that is often related to different cohorts that makes comparison between studies very difficult. What is New: • The real-world findings of this study, including all the children treated since treatments became available, confirmed that the need for tube feeding is not an invariable finding. • The level of feeding involvement at baseline appears to be a reliable prognostic indicator of bulbar outcome. • The results highlight the need for interventional studies with structured Speech and Language Therapist protocols that will help to better understand the extent to which bulbar function can be maintained or regained even in children requiring tube feeding.

Onasemnogene-abeparvovec administration to premature infants with spinal muscular atrophy

Twin girls born at 30 weeks' gestation with spinal muscular atrophy (SMA) received onsasemnogene-abeparvovec (OA) at 3.5 weeks of life. They had no treatment-related adverse events, normal acquisition of motor milestones, and normal neurological examination at 19 months. Genotyping revealed 0 copies of SMN1 and a single, hybrid SMN2 gene containing the positive genetic modifier c.835-44A>G. This was associated with full-length SMN2 blood mRNA expression levels similar to a 2 copy SMA infant. The observed favorable outcomes are likely due to the genetic modifier combined with early drug administration enabled by prematurity.

Outcomes for patients in the RESTORE registry with spinal muscular atrophy and four or more SMN2 gene copies treated with onasemnogene abeparvovec

OBJECTIVE

We describe outcomes following onasemnogene abeparvovec monotherapy for patients with ≥four survival motor neuron 2 (SMN2) gene copies in RESTORE, a noninterventional spinal muscular atrophy patient registry.

METHODS

We evaluated baseline characteristics, motor milestone achievement, post-treatment motor function, use of ventilatory/nutritional support, and adverse events as of December 22, 2022.

RESULTS

At data cutoff, 19 patients in RESTORE had ≥four SMN2 copies and were treated with onasemnogene abeparvovec monotherapy (n=12 [63.2%] four copies; n=7 [36.8%] >four copies). All patients were identified by newborn screening and were reported as asymptomatic at diagnosis. Median age at onasemnogene abeparvovec administration was 3.0 months. Median time from treatment to last recorded visit was 15.4 months, with a range of post-treatment follow-up of 0.03-39.4 months. All 12 children who were assessed for motor development achieved new milestones, including standing alone (n=2) and walking alone (n=5). Five children reported one or more treatment-emergent adverse events (one Grade 3 or greater). No deaths or use of ventilatory/nutritional support were reported.

CONCLUSIONS

Real-world findings from the RESTORE registry indicate that patients with ≥four SMN2 gene copies treated with onasemnogene abeparvovec monotherapy demonstrated improvements in motor function. Adverse events experienced by these patients were consistent with previously reported findings.

Newborn screening programs for spinal muscular atrophy worldwide in 2023

BACKGROUND

Spinal muscular atrophy is a rare, genetic neuromuscular disorder. Disease-modifying therapies, when administered early, have shown improved outcomes, leading to the implementation of numerous newborn screening programs for spinal muscular atrophy.

OBJECTIVE

The aim of this study was to evaluate the progress in implementing newborn screening for spinal muscular atrophy and therapy accessibility worldwide, after the first paper published in 2021.

METHODS

We conducted a survey, contacted experts from 143 countries worldwide, gathered responses from 86 experts from 80 countries.

RESULTS

By 2023, 31 countries reported established programs, 33 in the beginning of the year 2024; identifying approximately 1176 cases of spinal muscular atrophy. Additionally, the availability of disease-modifying therapies has expanded. At least one therapy is now accessible in 62 countries. Challenges, such as lack of governmental support, resource constraints, and varying healthcare priorities continue to impede implementation in some countries.

CONCLUSIONS

The data shows a significant increase in the implementation of newborn screening programs since 2021. The experts are still expressing a strong need for equitable access to standard of care for all the patients globally. Despite all setbacks, collaborative efforts have played a crucial role in newborn screening for spinal muscular atrophy implementation and currently 7% of world newborns are being screened, projections indicate an estimated 18% screening rate by 2028.

The Relevance of Spinal Muscular Atrophy Biomarkers in the Treatment Era

Spinal muscular atrophy (SMA) is a severe neuromuscular disorder that currently has an approved treatment for all forms of the disease. Previously, biomarkers were primarily used for diagnostic purposes, such as detecting the presence of the disease or determining a specific clinical type of SMA. Currently, with the availability of therapy, biomarkers have become more valuable due to their potential for prognostic, predictive, and pharmacodynamic applications. This review describes the most promising physiological, functional, imaging and molecular biomarkers for SMA, derived from different patients' tissues. The review summarizes information about classical biomarkers that are already used in clinical practice as well as fresh findings on promising biomarkers that have been recently disclosed. It highlights the usefulness, limitations, and strengths of each potential biomarker, indicating the purposes for which each is best suited and when combining them may be most beneficial.

Why should a 5q spinal muscular atrophy neonatal screening program be started?

Spinal muscular atrophy (SMA) is a genetic neuromuscular progressive disorder that is currently treatable. The sooner the disease-modifying therapies are started, the better the prognosis. Newborn screening for SMA, which is already performed in many countries, has been scheduled to begin in the near future. The development of a well-organized program is paramount to achieve favorable outcomes for the child who is born with the disease and for the costs involved in health care. We herein present a review paper hoping to point out that SMA neonatal screening is urgent and will not increase the cost of its care.

Onasemnogene abeparvovec gene therapy for spinal muscular atrophy: A cohort study from the United Arab Emirates

INTRODUCTION/AIMS

Spinal muscular atrophy (SMA) manifests with progressive motor neuron degeneration, leading to muscle weakness. Onasemnogene abeparvovec is a US Food and Drug Administration-approved gene replacement therapy for SMA. This study aimed to present short-term data of children in the United Arab Emirates (UAE) treated with onasemnogene abeparvovec, particularly in the context of children requiring invasive ventilatory support via tracheostomy.

METHODS

A retrospective analysis was performed on 60 children who received onasemnogene abeparvovec. All these children received corticosteroids. They were followed up for up to 3 months. Motor function assessments were performed before and after the gene therapy. Comprehensive clinical evaluations, including pulmonary functions, were performed at baseline and the 3-month mark.

RESULTS

Forty-three percent were male, and the mean age at the time of infusion was 29.6 months (SD ± 17.2). The mean weight was 10.1 kg (SD 2.6). All children demonstrated marked improvements in motor function within 3 months of gene therapy administration. No adverse effects attributable to corticosteroid therapy were observed. Positive clinical outcomes, including increased ventilator-free intervals, reduced antibiotic dependency, and fewer hospital admissions, were reported among children with invasive ventilation via tracheostomy.

DISCUSSION

This study demonstrates the favorable tolerability and promising responses to onasemnogene abeparvovec in invasively ventilated pediatric patients. Early improvements in motor function, as observed within 3 months post-treatment, suggest its potential as a viable therapeutic option for this vulnerable patient population.

Impact of respiratory tract infections on spinal muscular atrophy with focus on respiratory syncytial virus infections: a single-centre cohort study

AIMS OF THE STUDY

Spinal muscular atrophy (SMA) is a degenerative neuromuscular disorder leading to muscle hypotonia, weakness, and respiratory and bulbar impairment. Infants with SMA have an increased risk of respiratory tract infections (RTI) including severe respiratory syncytial virus (RSV) infections. Therefore, guidelines for the treatment of SMA recommend RSV prophylaxis with palivizumab for patients aged below two years who have compromised motor functions ("non-sitters"). Since palivizumab is not approved for RSV prophylaxis in SMA patients in Switzerland, payers usually do not grant cost approvals for this indication. Therefore, this study aimed to investigate the frequency of severe RTI among SMA patients focusing on RSV infections requiring hospital treatment and to determine the long-term impact of RSV infections on the natural history of SMA.

METHODS

A single-centre cohort study at the tertiary paediatric Neuromuscular Centre Zurich, Switzerland, including data of SMA patients with a genetic-based therapy initiated below two years of age between May 2019 and December 2022. All hospitalisations were analysed with a focus on severe RTI and especially RSV infections, and their impact on nutritional and respiratory function. The costs of inpatient treatment of RSV infections were determined and compared with estimated expenses for RSV prophylaxis with palivizumab.

RESULTS

12 SMA patients (median age at treatment initiation: 3.5 months, range: 0-17 months) were followed for a cumulative period of 25.75 years (7 SMA type 1; 5 SMA type 2 including one presymptomatic individual). With an incidence rate of 2.34 per patient-year, the risk of severe RTI was especially high in SMA type 1 (versus 0.1 in SMA type 2, p = 0.044). A total of 37 hospitalisations (279 hospital days) was necessary for the treatment of RTI in general; 9 of them were attributed to RSV infections (in 5 SMA type 1 patients; 84 hospital days). Only 3/12 SMA patients had received seasonal RSV prophylaxis with palivizumab. No RSV infections requiring hospital treatment occurred in patients while receiving seasonal RSV prophylaxis. During RTI, nutritional support had to be commonly initiated and continued after discharge. In 3/7 SMA type 1 patients, non-invasive ventilation was started during acute treatment for RTI and continued to the end of follow-up.

CONCLUSION

We observed a high risk of RTI, especially RSV infections, among young SMA patients. Failure to adhere to established care protocols, for example by omitting RSV prophylaxis, may be linked to a heightened risk of morbidity in these children.

Clinical and Genetic Profiles of 5q- and Non-5q-Spinal Muscular Atrophy Diseases in Pediatric Patients

BACKGROUND

Spinal muscular atrophy (SMA) is a genetic disease characterized by loss of motor neurons in the spinal cord and lower brainstem. The term "SMA" usually refers to the most common form, 5q-SMA, which is caused by biallelic mutations in SMN1 (located on chromosome 5q13). However, long before the discovery of SMN1, it was known that other forms of SMA existed. Therefore, SMA is currently divided into two groups: 5q-SMA and non-5q-SMA. This is a simple and practical classification, and therapeutic drugs have only been developed for 5q-SMA (nusinersen, onasemnogene abeparvovec, risdiplam) and not for non-5q-SMA disease.

METHODS

We conducted a non-systematic critical review to identify the characteristics of each SMA disease.

RESULTS

Many of the non-5q-SMA diseases have similar symptoms, making DNA analysis of patients essential for accurate diagnosis. Currently, genetic analysis technology using next-generation sequencers is rapidly advancing, opening up the possibility of elucidating the pathology and treating non-5q-SMA.

CONCLUSION

Based on accurate diagnosis and a deeper understanding of the pathology of each disease, treatments for non-5q-SMA diseases may be developed in the near future.

Postnatal management of preterm infants with spinal muscular atrophy: experience from German newborn screening

BACKGROUND

The introduction of newborn screening (NBS) for spinal muscular atrophy (SMA) has increased the early diagnosis of 5q-associated SMA in presymptomatic and symptomatic preterm infants. National and international recommendations for treating preterms and newborns < 38 weeks of gestational age are unavailable. Our retrospective multicentre study aimed to evaluate the postnatal clinical course of preterm infants with 5q-associated SMA diagnosed since the implementation of NBS in Germany in 2021 and to summarize the German experience regarding the decision-making process for available treatment regimens for preterm infants with ≤ 3 survival of motor neuron 2 (SMN2) copies.

RESULTS

Twelve preterm infants with 5q-associated SMA and a mean gestational age of 34.0 weeks (range: 26.1-36.8) and birth weight of 2022 g (range: 645-3370) were reported from 8/20 German SMA NBS follow-up centers using a pseudonymized questionnaire. Confirmatory diagnosis, including SMN2 copy number, was completed on average on postnatal day 13. All patients had a biallelic deletion of exon 7 or exons 7 and 8 of the survival of motor neuron 1 (SMN1) gene, with SMN2 copy numbers of two in 10 patients and three in two patients. The neonatal course was complicated by respiratory distress due to prematurity (n = 2), sepsis (n = 2), and jaundice (n = 2). At birth, 11 preterm infants (91.6%) were presymptomatic. However, the neurological status of one patient deteriorated at five weeks of age (postconceptional age of 41.8 weeks) prior to the start of treatment. Disease-modifying treatments were initiated in all patients at a mean postconceptional age of 38.8 weeks, with the majority receiving onasemnogene abeparvovec (83.3%, including 2 patients with prior risdiplam bridge therapy). Notably, consensus among participating experts from German neuromuscular centers resulted in 83.3% of patients receiving disease-modifying treatment at term.

CONCLUSIONS

Premature infants with SMA require interdisciplinary care in close collaboration with the neuromuscular center. SMA NBS facilitates early initiation of disease-modifying therapy, ideally during the presymptomatic phase, which significantly influences the prognosis of the newborn.

A Study on the Incidence and Prevalence of 5q Spinal Muscular Atrophy in Canada Using Multiple Data Sources

OBJECTIVES

Spinal muscular atrophy (SMA) is a leading genetic cause of infant death and represents a significant burden of care. An improved understanding of the epidemiology of SMA in Canada may help inform strategies to improve the standard of care for individuals living with SMA.

METHODS

We employed a multisource approach to estimate the minimal incidence and prevalence of 5q SMA and to gain greater insight into recent clinical practices and treatment trends for the Canadian SMA population. Data sources included the Canadian Paediatric Surveillance Program (CPSP), Canadian Neuromuscular Disease Registry (CNDR), and molecular genetics laboratories in Canada.

RESULTS

The estimated annual minimum incidence of 5q SMA was 4.38, 3.44, and 7.99 cases per 100,000 live births in 2020 and 2021, based on CPSP, CNDR, and molecular genetics laboratories data, respectively, representing approximately 1 in 21,472 births (range 12,516-29,070) in Canada. SMA prevalence was estimated to be 0.85 per 100,000 persons aged 0-79 years. Delay in diagnosis exists across all SMA subtypes. Most common presenting symptoms were delayed milestones, hypotonia, and muscle weakness. Nusinersen was the most common disease-modifying treatment received. Most patients utilized multidisciplinary clinics for management of SMA.

CONCLUSION

This study provides data on the annual minimum incidence of pediatric 5q SMA in Canada. Recent therapeutic advances and newborn screening have the potential to drastically alter the natural history of SMA. Findings underline the importance of ongoing surveillance of the epidemiology and long-term health outcomes of SMA in the Canadian population.

Impact of Disease-modifying Therapies on Respiratory Function in People with Neuromuscular Disorders

Spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD) are neuromuscular disorders that affect muscular function. The most common causes of morbidity and mortality are respiratory complications, including restrictive lung disease, ineffective cough, and sleep-disordered breathing. The paradigm of care is changing as new disease-modifying therapies are altering disease trajectory, outcomes, expectations, as well as patient and caregiver experiences. This article provides an overview on therapeutic advances for SMA and DMD in the last 10 years, with a focus on the effects of disease-modifying therapies on respiratory function.

Gene and cell therapy of human genetic diseases: Recent advances and future directions

Disruptions in normal development and the emergence of health conditions often result from the malfunction of vital genes in the human body. Decades of scientific research have focused on techniques to modify or substitute defective genes with healthy alternatives, marking a new era in disease treatment, prevention and cure. Recent strides in science and technology have reshaped our understanding of disorders, medication development and treatment recommendations, with human gene and cell therapy at the forefront of this transformative shift. Its primary objective is the modification of genes or adjustment of cell behaviour for therapeutic purposes. In this review, we focus on the latest advances in gene and cell therapy for treating human genetic diseases, with a particular emphasis on FDA and EMA-approved therapies and the evolving landscape of genome editing. We examine the current state of innovative gene editing technologies, particularly the CRISPR-Cas systems. As we explore the progress, ethical considerations and prospects of these innovations, we gain insight into their potential to revolutionize the treatment of genetic diseases, along with a discussion of the challenges associated with their regulatory pathways. This review traces the origins and evolution of these therapies, from conceptual ideas to practical clinical applications, marking a significant milestone in the field of medical science.