Gene replacement therapy with onasemnogene abeparvovec in children with spinal muscular atrophy aged 24 months or younger and bodyweight up to 15 kg: an observational cohort study

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.

A systematic review of immunosuppressive protocols used in AAV gene therapy for monogenic disorders

The emergence of adeno-associated virus (AAV)-based gene therapy has brought hope to patients with severe monogenic disorders. However, immune responses to AAV vectors and transgene products present challenges that require effective immunosuppressive strategies. This systematic review focuses on the immunosuppressive protocols used in 38 clinical trials and 35 real-world studies, considering a range of monogenic diseases, AAV serotypes, and administration routes. The review underscores the need for a deeper understanding of immunosuppressive regimens to enhance the safety and effectiveness of AAV-based gene therapy. Characterizing the immunological responses associated with various gene therapy treatments is crucial for optimizing treatment protocols and ensuring the safety and efficacy of forthcoming gene therapy interventions. Further research and understanding of the impact of immunosuppression on disease, therapy, and route of administration will contribute to the development of more effective and safer gene therapy approaches in the future.

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.

Real-world multidisciplinary outcomes of onasemnogene abeparvovec monotherapy in patients with spinal muscular atrophy type 1: experience of the French cohort in the first three years of treatment

BACKGROUND

Spinal muscular atrophy type 1 (SMA1) is the most severe and early form of SMA, a genetic disease with motor neuron degeneration. Onasemnogene abeparvovec gene transfer therapy (GT) has changed the natural history of SMA1, but real-world data are scarce.

METHODS

A French national expert committee identified 95 newly diagnosed treatment-naive SMA1 patients between June 2019 and June 2022. We prospectively report on children treated with GT as the first and only therapy who had more than one-year of follow-up.

RESULTS

Forty-six SMA1 patients received GT. Twelve patients received other treatments. Patients with respiratory insufficiency were oriented toward palliative care after discussion with families. Twenty-nine of the treated patients with more than 12 months of follow-up were included in the follow-up analysis. Among them, 17 had 24 months of follow-up. The mean age at treatment was 7.5 (2.1-12.5) months. Twenty-two patients had two SMN2 copies, and seven had three copies. One infant died in the month following GT due to severe thrombotic microangiopathy, and another died due to respiratory distress. Among the 17 patients with 24 months of follow-up, 90% required spinal bracing (15/17), three patients required nocturnal noninvasive ventilation, and two needed gastrostomy. Concerning motor milestones at the 24-month follow-up, all patients held their head, 15/17 sat for 30 s unassisted, and 12/17 stood with aid. Motor scores (CHOPINTEND and HINE-2) and thoracic circumference significantly improved in all patients.

CONCLUSIONS

Our study shows favorable motor outcomes and preserved respiratory and feeding functions in treatment-naive SMA1 infants treated by GT as the first and only therapy before respiratory and bulbar dysfunctions occurred. Nevertheless, almost all patients developed spinal deformities.

Risk-benefit profile of onasemnogene abeparvovec in older and heavier children with spinal muscular atrophy type 1

Spinal muscular atrophy (SMA) is an autosomal recessive disorder with progressive muscle atrophy and weakness, caused by biallelic mutations in the survival motor neuron 1 (SNM1) gene. Onasemnogene abeparvovec (OA) is an approved gene replacement therapy for patients with SMA. We report on two patients with SMA type 1, weighing 20 kg, previously treated with Nusinersen, who received OA infusion at 7 years of age. To our knowledge, these two patients are the heaviest treated in the real-world and we describe their different courses after gene therapy, including liver impairment requiring long-term steroid treatment and additional immunosuppression, with only transitory improvement in functional outcomes. Our cases illustrate how careful risk-benefit consideration is required in treating older and heavier SMA patients with OA, especially in view of the multiple treatment choices available for older patients with SMA.

Systematic Review of Presymptomatic Treatment for Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) causes the degeneration of motor neurons in the spinal cord. Treatments including nusinersen, risdiplam, and onasemnogene abeparvovec have been shown to be effective in reducing symptoms, with recent studies suggesting greater effectiveness when treatment is initiated in the presymptomatic stage. This systematic review synthesises findings from prospective studies of presymptomatic treatment for 5q SMA published up to December 2023. The review identified three single-arm interventional studies of presymptomatic treatment (NURTURE, RAINBOWFISH, and SPR1NT), six observational studies comparing presymptomatic or screened cohorts versus symptomatic cohorts, and twelve follow-up studies of screened cohorts only (i.e., babies identified via newborn screening for SMA). Babies with three SMN2 copies met most motor milestones in the NURTURE study of nusinersen and in the SPR1NT study of onasemnogene abeparvovec. Babies with two SMN2 copies in these two studies met most motor milestones but with some delays, and some required ventilatory or feeding support. The RAINBOWFISH study of risdiplam is ongoing. Naïve comparisons of presymptomatic treatment in SPR1NT, versus untreated or symptomatic treatment cohorts, suggested improved outcomes in patients treated presymptomatically. Comparative observational studies supported the finding that presymptomatic treatment, and early treatment following screening, may improve outcomes compared with treatment at the symptomatic stage. Further research should assess the long-term clinical outcomes and cost-effectiveness of presymptomatic treatment for SMA.

Clinical perspectives: Treating spinal muscular atrophy

Spinal muscular atrophy is a rare and progressive neuromuscular disease that, without treatment, leads to progressive weakness and often death. A plethora of studies have led to the approval of three high-cost and effective treatments since 2016. These treatments, nusinersen, onasemnogene abeparvovec, and risdiplam, have not been directly compared and have varying challenges in administration. In this review, we discuss the evidence supporting the use of these medications, the process of treatment selection, monitoring after treatment, the limited data comparing treatments, as well as future directions for investigation and therapy.

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

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

Polysomnography findings and respiratory muscle function in infants with early onset spinal muscular atrophy after gene replacement as monotherapy: A prospective study

BACKGROUND

Gene replacement therapy (onasemnogene abeparvovec) is associated with an improvement of the prognosis of children with spinal muscular atrophy, but information on long-term respiratory outcome is scarce. The aim of this study was to report the polysomnography findings and respiratory muscle function of infants with treatment-naive spinal muscular atrophy type 1 and 2 up to 24 months after onasemnogene abeparvovec monotherapy.

METHODS

A clinical and motor evaluation, respiratory muscle function testing, and polysomnography were performed repeatedly.

RESULTS

Fifteen spinal muscular atrophy patients (1 presymptomatic, 7 type 1b, 6 type 1c, and 1 type 2) were included at a median age of 8.6 months (range 3.8-12.6) and followed for 24 months. The thoracic over head circumference ratio was close to normal at baseline (median 1.00 (range 0.90-1.05)) and increased significantly over time. All polysomnography and nocturnal gas exchange parameters were within normal ranges at baseline (median apnea-hypopnea index 2.5 events/hour (range 0.4-5.3)) and follow-up. The inspiratory muscle strength was normal at baseline but tended to slightly decrease over time and the expiratory muscle strength was low at any time especially for patients with recurrent respiratory infections (median (range) at baseline in cmH2O: crying esophageal pressure 54 (30-110), crying transdiaphragmatic pressure 65 (35-107), gastric pressure during maximal cough 26 (10-130), esophageal pressure during maximal cough 61 (38-150)). Only 3 patients required noninvasive ventilation.

CONCLUSION

A continuous respiratory monitoring of spinal muscular atrophy patients during the first years of life following onasemnogene abeparvovec monotherapy seems recommended despite the normality of polysomnography parameters.

2024 update: European consensus statement on gene therapy for spinal muscular atrophy

Spinal muscular atrophy (SMA) is one of the most common genetic diseases and was, until recently, a leading genetic cause of infant mortality. Three disease-modifying treatments have dramatically changed the disease trajectories and outcome for severely affected infants (SMA type 1), especially when initiated in the presymptomatic phase. One of these treatments is the adeno-associated viral vector 9 (AAV9) based gene therapy onasemnogene abeparvovec (Zolgensma®), which is delivered systemically and has been approved by the European Medicine Agency for SMA patients with up to three copies of the SMN2 gene or with the clinical presentation of SMA type 1. While this broad indication provides flexibility in patient selection, it also raises concerns about the risk-benefit ratio for patients with limited or no evidence supporting treatment. In 2020, we convened a European neuromuscular expert working group to support the rational use of onasemnogene abeparvovec, employing a modified Delphi methodology. After three years, we have assembled a similar yet larger group of European experts who assessed the emerging evidence of onasemnogene abeparvovec's role in treating older and heavier SMA patients, integrating insights from recent clinical trials and real-world evidence. This effort resulted in 12 consensus statements, with strong consensus achieved on 9 and consensus on the remaining 3, reflecting the evolving role of onasemnogene abeparvovec in treating SMA.

Gene replacement therapy for spinal muscular atrophy: safety and preliminary efficacy in a Brazilian cohort

Spinal muscular atrophy (SMA) is a motor neuron disease associated with progressive muscle weakness, ventilatory failure, and reduced survival. Onasemnogene abeparvovec is the first gene replacement therapy (GT) approved to treat this condition. An observational retrospective study was conducted to assess adverse events and efficacy of GT in SMA patients. Forty-one patients with SMA (58.5% females and 80.1% SMA type 1) were included. The mean age at GT dosing was 18 (±6.4) months. Thirty-six patients (87.8%) were under previous treatment with nusinersen, and 10 (24.4%) continued nusinersen after GT. Mean CHOP-INTEND increased 13 points after 6 months and this finding did not differ between groups according to nusinersen maintenance after GT (p = 0.949). Among SMA type 1 patients, 14 (46.6%) reached the ability to sit alone. Liver transaminases elevation at least two times higher than the upper limit of normal value occurred in 29 (70.7%) patients. Thrombocytopenia occurred in 13 (31.7%) patients, and one presented thrombotic microangiopathy. Older age (>2 years) was associated with more prolonged use of corticosteroids (p = 0.021). GT is effective in SMA patients, combined nusinersen after GT did not appear to add gain in motor function and older age is associated with prolonged corticosteroid use.

Cognitive function in SMA patients with 2 or 3 SMN2 copies treated with SMN-modifying or gene addition therapy during the first year of life

BACKGROUND

Spinal muscular atrophy (SMA) is a neuromuscular disease, causing progressive muscle weakness due to loss of lower motoneurons. Since 2017, three therapies, two modifying gene transcription and one adding the defective gene, have been approved with comparable efficacy on motor outcome. Data on cognitive outcomes of treated SMA type 1 patients is limited. The aim of this study was to evaluate cognitive function in symptomatic and presymptomatic SMA type 1 patients with two or three SMN2 copies who received SMN-modifying or gene-addition therapy in the first year of life.

METHODS

Cognitive testing was performed in 20 patients, including 19 symptomatic SMA type 1 patients with up to three SMN2 copies and 1 pre-symptomatically treated patient. Children were tested using Bayley Scales of Infant Development (BSID-III) at the age of 2 or 3 years or the Wechsler Preschool and Primary Scale of Intelligence (WPSII-IV) at the of age of 5 years.

RESULTS

11/20 patients showed subnormal cognitive development. Boys had significantly lower cognitive scores. Patients requiring assisted ventilation or feeding support were more likely to have cognitive deficits. Achieving more motor milestones was associated with a better cognitive outcome.

CONCLUSION

Treated patients with SMA type 1 have heterogeneous cognitive function with 55 % of patients showing deficits. Risk factors for cognitive impairment in our cohort were male gender and need for assisted ventilation or feeding support. Therefore, cognitive assessment should be included in the standard of care to allow early identification of deficits and potential therapeutic interventions.

Gene-based therapies for neuromuscular disorders

Neuromuscular diseases (NMD) include a broad group of medical conditions with both acquired and genetic causes. In recent years, important advances have been made in the treatment of genetically caused NMD, and most of these advances are due to the implementation of therapies aimed at gene regulation. Among these therapies, gene replacement, small interfering RNA (siRNA), and antisense antinucleotides are the most promising approaches. More importantly, some of these therapies have already gained regulatory approval or are in the final stages of approval. The review focuses on motor neuron diseases, neuropathies, and Duchenne muscular dystrophy, summarizing the most recent developments in gene-based therapies for these conditions.

An interpretable data-driven prediction model to anticipate scoliosis in spinal muscular atrophy in the era of (gene-) therapies

5q-spinal muscular atrophy (SMA) is a neuromuscular disorder (NMD) that has become one of the first 5% treatable rare diseases. The efficacy of new SMA therapies is creating a dynamic SMA patient landscape, where disease progression and scoliosis development play a central role, however, remain difficult to anticipate. New approaches to anticipate disease progression and associated sequelae will be needed to continuously provide these patients the best standard of care. Here we developed an interpretable machine learning (ML) model that can function as an assistive tool in the anticipation of SMA-associated scoliosis based on disease progression markers. We collected longitudinal data from 86 genetically confirmed SMA patients. We selected six features routinely assessed over time to train a random forest classifier. The model achieved a mean accuracy of 0.77 (SD 0.2) and an average ROC AUC of 0.85 (SD 0.17). For class 1 'scoliosis' the average precision was 0.84 (SD 0.11), recall 0.89 (SD 0.22), F1-score of 0.85 (SD 0.17), respectively. Our trained model could predict scoliosis using selected disease progression markers and was consistent with the radiological measurements. During post validation, the model could predict scoliosis in patients who were unseen during training. We also demonstrate that rare disease data sets can be wrangled to build predictive ML models. Interpretable ML models can function as assistive tools in a changing disease landscape and have the potential to democratize expertise that is otherwise clustered at specialized centers.

Gene therapy corrects the neurological deficits of mice with sialidosis

Patients with sialidosis (mucolipidosis type I) type I typically present with myoclonus, seizures, ataxia, cherry-red spots, and blindness because of mutations in the neuraminidase 1 (NEU1) gene. Currently, there is no treatment for sialidosis. In this study, we developed an adeno-associated virus (AAV)-mediated gene therapy for a Neu1 knockout (Neu1-/-) mouse model of sialidosis. The vector, AAV9-P3-NP, included the human NEU1 promoter, NEU1 cDNA, IRES, and CTSA cDNA. Untreated Neu1-/- mice showed astrogliosis and microglial LAMP1 accumulation in the nervous system, including brain, spinal cord, and dorsal root ganglion, together with impaired motor function. Coexpression of NEU1 and protective protein/cathepsin A (PPCA) in neonatal Neu1-/- mice by intracerebroventricular injection, and less effective by facial vein injection, decreased astrogliosis and LAMP1 accumulation in the nervous system and improved rotarod performance of the treated mice. Facial vein injection also improved the grip strength and survival of Neu1-/- mice. Therefore, cerebrospinal fluid delivery of AAV9-P3-NP, which corrects the neurological deficits of mice with sialidosis, could be a suitable treatment for patients with sialidosis type I. After intracerebroventricular or facial vein injection of AAV vectors, NEU1 and PPCA are expressed together. PPCA-protected NEU1 is then sent to lysosomes, where β-Gal binds to this complex to form a multienzyme complex in order to execute its function.

Adeno-associated virus as a delivery vector for gene therapy of human diseases

Adeno-associated virus (AAV) has emerged as a pivotal delivery tool in clinical gene therapy owing to its minimal pathogenicity and ability to establish long-term gene expression in different tissues. Recombinant AAV (rAAV) has been engineered for enhanced specificity and developed as a tool for treating various diseases. However, as rAAV is being more widely used as a therapy, the increased demand has created challenges for the existing manufacturing methods. Seven rAAV-based gene therapy products have received regulatory approval, but there continue to be concerns about safely using high-dose viral therapies in humans, including immune responses and adverse effects such as genotoxicity, hepatotoxicity, thrombotic microangiopathy, and neurotoxicity. In this review, we explore AAV biology with an emphasis on current vector engineering strategies and manufacturing technologies. We discuss how rAAVs are being employed in ongoing clinical trials for ocular, neurological, metabolic, hematological, neuromuscular, and cardiovascular diseases as well as cancers. We outline immune responses triggered by rAAV, address associated side effects, and discuss strategies to mitigate these reactions. We hope that discussing recent advancements and current challenges in the field will be a helpful guide for researchers and clinicians navigating the ever-evolving landscape of rAAV-based gene therapy.

Vaccination proposal for patients on onasemnogene abeparvovec therapy

The approval of disease-modifying treatment in spinal muscular atrophy made the condition less severe. The course of the disease changed, but some new concerns occurred with the different new therapies. The side effects of onasemnogene aboparvovec therapy can raise differential diagnostic challenges and necessitate immune therapy, leading to immunosuppression affecting response to vaccines. We provide a pretherapy screening proposal from an infectological point of view separately for newborns treated presymptomatically and children diagnosed with symptoms at any age. Furthermore, we summarise the guidelines on the vaccination before, during, and after immune therapy (steroids) in onasemnogene aboparvovec-treated patients.

Motor and neurocognitive profiles of children with symptomatic spinal muscular atrophy type 1 with two copies of SMN2 before and after treatment: a longitudinal observational study

Introduction

Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by mutations in the survival motor neuron 1 (SMN1) gene. In clinical studies, gene replacement therapy with onasemnogene abeparvovec (formerly AVXS-101, Zolgensma®, Novartis) was efficacious in improving motor functioning in children with SMA. However, its effects on cognitive and language skills are largely unknown.

Methods

This longitudinal observational study evaluated changes in motor and neurocognitive functioning over a 1-year period after administration of onasemnogene abeparvovec in 12 symptomatic SMA type 1 patients with two copies of SMN2 aged 1.7-52.6 months at administration. Motor functioning was measured using the Children's Hospital of Philadelphia Infant Test for Neuromuscular Disorders (CHOP-INTEND) while neurocognitive assessment was measured using Griffiths III. Motor milestones and language ability were also assessed at each timepoint.

Results and discussion

Statistically significant increases in median CHOP-INTEND scores from baseline were observed at 1, 3, 6, and 12 months after onasemnogene abeparvovec administration (all p ≤ 0.005). Most (91.7%) patients were able to roll over or sit independently for >1 min at 12 months. Significant increases in the Griffiths III Foundations of Learning, Language and Communication, Eye and Hand Coordination, and Personal-Social-Emotional subscale scores were observed at 12-months, but not in the Gross Motor subscale. Speech and language abilities progressed in most patients. Overall, most patients showed some improvement in cognitive and communication performance after treatment with onasemnogene abeparvovec in addition to significant improvement in motor functioning and motor milestones. Evaluation of neurocognitive function should be considered when assessing the global functioning of patients with SMA.

Efficacy and safety of onasemnogene abeparvovec in children with spinal muscular atrophy type 1: real-world evidence from 6 infusion centres in the United Kingdom

Background

Real-world data on the efficacy and safety of onasemnogene abeparvovec (OA) in spinal muscular atrophy (SMA) are needed, especially to overcome uncertainties around its use in older and heavier children. This study evaluated the efficacy and safety of OA in patients with SMA type 1 in the UK, including patients ≥2 years old and weighing ≥13.5 kg.

Methods

This observational cohort study used data from patients with genetically confirmed SMA type 1 treated with OA between May 2021 and January 2023, at 6 infusion centres in the United Kingdom. Functional outcomes were assessed using age-appropriate functional scales. Safety analyses included review of liver function, platelet count, cardiac assessments, and steroid requirements.

Findings

Ninety-nine patients (45 SMA therapy-naïve) were treated with OA (median age at infusion: 10 [range, 0.6-89] months; median weight: 7.86 [range, 3.2-20.2] kg; duration of follow-up: 3-22 months). After OA infusion, mean ± SD change in CHOP-INTEND score was 11.0 ± 10.3 with increased score in 66/78 patients (84.6%); patients aged <6 months had a 13.9 points higher gain in CHOP-INTEND score than patients ≥2 years (95% CI, 6.8-21.0; P < 0.001). Asymptomatic thrombocytopenia (71/99 patients; 71.7%), asymptomatic troponin-I elevation (30/89 patients; 33.7%) and transaminitis (87/99 patients; 87.9%) were reported. No thrombotic microangiopathy was observed. Median steroid treatment duration was 97 (range, 28-548) days with dose doubled in 35/99 patients (35.4%). There were 22.5-fold increased odds of having a transaminase peak >100 U/L (95% CI, 2.3-223.7; P = 0.008) and 21.2-fold increased odds of steroid doubling, as per treatment protocol (95% CI, 2.2-209.2; P = 0.009) in patients weighing ≥13.5 kg versus <8.5 kg. Weight at infusion was positively correlated with steroid treatment duration (r = 0.43; P < 0.001). Worsening transaminitis, despite doubling of oral prednisolone, led to treatment with intravenous methylprednisolone in 5 children. Steroid-sparing immunosuppressants were used in 5 children to enable steroid weaning. Two deaths apparently unrelated to OA were reported.

Interpretation

OA led to functional improvements and was well tolerated with no persistent clinical complications, including in older and heavier patients.

Funding

Novartis Innovative Therapies AG provided a grant for independent medical writing services.

Challenges and opportunities in spinal muscular atrophy therapeutics

Spinal muscular atrophy was the most common inherited cause of infant death until 2016, when three therapies became available: the antisense oligonucleotide nusinersen, gene replacement therapy with onasemnogene abeparvovec, and the small-molecule splicing modifier risdiplam. These drugs compensate for deficient survival motor neuron protein and have improved lifespan and quality of life in infants and children with spinal muscular atrophy. Given the lifelong implications of these innovative therapies, ways to detect and manage treatment-modified disease characteristics are needed. All three drugs are more effective when given before development of symptoms, or as early as possible in individuals who have already developed symptoms. Early subtle symptoms might be missed, and disease onset might occur in utero in severe spinal muscular atrophy subtypes; in some countries, newborn screening is allowing diagnosis soon after birth and early treatment. Adults with spinal muscular atrophy report stabilisation of disease and less fatigue with treatment. These subjective benefits need to be weighed against the high costs of the drugs to patients and health-care systems. Clinical consensus is required on therapeutic windows and on outcome measures and biomarkers that can be used to monitor drug benefit, toxicity, and treatment-modified disease characteristics.

Real-World Outcomes in Patients with Spinal Muscular Atrophy Treated with Onasemnogene Abeparvovec Monotherapy: Findings from the RESTORE Registry

Background

Long-term, real-world effectiveness and safety data of disease-modifying treatments for spinal muscular atrophy (SMA) are important for assessing outcomes and providing information for a larger number and broader range of SMA patients than included in clinical trials.

Objective

We sought to describe patients with SMA treated with onasemnogene abeparvovec monotherapy in the real-world setting.

Methods

RESTORE is a prospective, multicenter, multinational, observational registry that captures data from a variety of sources.

Results

Recruitment started in September 2018. As of May 23, 2022, data were available for 168 patients treated with onasemnogene abeparvovec monotherapy. Median (IQR) age at initial SMA diagnosis was 1 (0-6) month and at onasemnogene abeparvovec infusion was 3 (1-10) months. Eighty patients (47.6%) had two and 70 (41.7%) had three copies of SMN2, and 98 (58.3%) were identified by newborn screening. Infants identified by newborn screening had a lower age at final assessment (mean age 11.5 months) and greater mean final (SD) CHOP INTEND score (57.0 [10.0] points) compared with clinically diagnosed patients (23.1 months; 52.1 [8.0] points). All patients maintained/achieved motor milestones. 48.5% (n = 81/167) experienced at least one treatment-emergent adverse event (AE), and 31/167 patients (18.6%) experienced at least one serious AE, of which 8/31 were considered treatment-related.

Conclusion

These real-world outcomes support findings from the interventional trial program and demonstrate effectiveness of onasemnogene abeparvovec over a large patient population, which was consistent with initial clinical data and published 5-year follow-up data. Observed AEs were consistent with the established safety profile of onasemnogene abeparvovec.

Continued safety and long-term effectiveness of onasemnogene abeparvovec in Ohio

5q spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disease caused by absence of the SMN1 gene with three FDA approved genetic therapies which significantly improve outcomes. The AAV9 mediated gene replacement therapy, onasemnogene abeparvovec, has the greatest potential for side effects. Here we report the safety and outcomes from 46 children treated with onasemnogene abeparvovec in the state of Ohio between December 2018 and January 2023. In our cohort, onasemnogene abeparvovec treatment remained safe and no child experienced any significant adverse events, including thrombotic microangiopathy, liver failure or death. All children experienced benefit, although the benefit in those with 2 copies of SMN2 was variable. 79 % of the children treated when symptomatic had a SMN2 modifying therapy added on. With careful screening and post treatment monitoring, onasemnogene abeparvovec is safe and effective for children with SMA in the state of Ohio, but more work needs to be done to ensure optimal outcomes for all children with 2 copies of SMN2.

Fetal gene therapy

Fetal gene therapy was first proposed toward the end of the 1990s when the field of gene therapy was, to quote the Gartner hype cycle, at its "peak of inflated expectations." Gene therapy was still an immature field but over the ensuing decade, it matured and is now a clinical and market reality. The trajectory of treatment for several genetic diseases is toward earlier intervention. The ability, capacity, and the will to diagnose genetic disease early-in utero-improves day by day. A confluence of clinical trials now signposts a trajectory toward fetal gene therapy. In this review, we recount the history of fetal gene therapy in the context of the broader field, discuss advances in fetal surgery and diagnosis, and explore the full ambit of preclinical gene therapy for inherited metabolic disease.

Paradoxical increase of neurofilaments in SMA patients treated with onasemnogene abeparvovec-xioi

Background/Objective

Neurofilament light chain (NfL) has been proposed as a biomarker reflecting disease severity and therapy response in children with spinal muscular atrophy type 1 and 2 (SMA1 and 2). The objective of this study was to examine how serum NfL changes after gene replacement therapy (GRT) with onasemnogene abeparvovec-xioi.

Methods

We measured NfL in serum probes from 19 patients (10 SMA 1 and 6 SMA 2; 15 previously treated with nusinersen or risdiplam; 12 male) before and at variable time points after GRT. These values were related to motor scores (CHOP-Intend, HFMSE and RULM).

Results

Median age at GRT was 19 months (range 2-46 months). Median NfL of all patients before GRT was 39 pg/ml (range 0-663 pg/ml; normal values <25 pg/ml), increased significantly to 297 pg/ml (range 61-1,696 pg/ml; p<0,002) 1 month after GRT, and decreased to 49 pg/ml (range 24-151 pg/ml) after 6 months. Subjects pre-treated with nusinersen or risdiplam had lower baseline NfL levels than naïve patients (p<0,005), but absolute increases of NfL were similar in both groups. While motor scores were improved in 14 out of 18 SMA patients (78%) 6 months after GRT NfL values differed not significantly from those measured at baseline (p = 0,959).

Conclusion

Serum NfL showed a paradoxical transient increase after GRT in both, pre-treated and naïve patients, which may reflect an immunological reaction in the CNS related to transfection of neuronal cells by AAV9. The clinical meaning of this increase should be assessed in future studies. Our findings encourage regular monitoring of NfL in OA treated patients.

Patient and Caregiver Outcomes After Onasemnogene Abeparvovec Treatment: Findings from the Cure SMA 2021 Membership Survey

INTRODUCTION

Onasemnogene abeparvovec (OA) is the only gene replacement therapy currently approved for spinal muscular atrophy (SMA) treatment. We sought to assess real-world patient and caregiver outcomes after OA treatment for SMA.

METHODS

Patients who received OA were identified from the 2021 Cure SMA Membership Survey. Those treated at 6-23 months of age were matched to non-patients treated with OA on the basis of age at the time of survey and survival motor neuron 2 gene copy number. Patient characteristics, motor milestones, and resource and supportive care use, as well as caregiver proxy-reported health-related quality of life (HRQOL), were described. Caregiver unmet needs and HRQOL were also assessed.

RESULTS

Of the 614 patients in the survey, 64 received OA, and 17 were matched with 28 non-OA-treated patients. In general, a greater percentage of OA-treated patients achieved various motor milestones, including 100% sitting without support and 58.8% walking with assistance. OA-treated patients also had numerically lower rates of hospitalization and surgery. None required tracheostomy with a ventilator. The rate of using oxygen or a breathing machine for more than 16 h was also lower for OA-treated patients. OA-treated patients had less frequent trouble swallowing. HRQOL was reported to be similar to non-OA-treated patients. Caregivers of OA-treated patients reported better patient mobility scores and less work impairment.

CONCLUSIONS

The study suggests that treatment with OA is associated with greater rates of motor milestone achievements and less resource and supportive care use for patients with SMA treated at 6-23 months of age in the real world. For caregivers, it may also potentially reduce unmet needs, improve HRQOL, and reduce work impairment.

Safety Concerns with Nusinersen, Risdiplam, and Onasemnogene Abeparvovec in Spinal Muscular Atrophy: A Real-World Pharmacovigilance Study

BACKGROUND AND OBJECTIVE

Spinal muscular atrophy (SMA) is a genetic disorder with limited treatment options. It is crucial to have a comprehensive understanding of drug safety in order to make informed clinical drug selections for patients with SMA. Assessing the safety profiles of therapeutic drugs for SMA has been challenging due to the limited number of patients included in clinical trials. This study aims to investigate and compare the potential safety concerns associated with three leading SMA therapeutic drugs: nusinersen, risdiplam, and onasemnogene abeparvovec.

METHODS

The FDA Adverse Event Reporting System database was used to analyze drug safety, and a case (SMA drug)/noncase (all other drugs in the database) approach was employed to estimate safety signals through disproportionality analysis and reporting odds ratio (ROR). Veen analysis was conducted to compare and select the idiosyncratic adverse events (AEs) associated with each drug.

RESULTS

The study included 5324 cases of nusinersen, 1184 cases of risdiplam, and 1277 cases of onasemnogene abeparvovec. Venn analysis revealed 27 common AEs among the three drugs, including cardiac, gastrointestinal, metabolism, musculoskeletal, renal, respiratory disorders, and infections. Additionally, 196 AEs exclusively found in nusinersen included post lumbar puncture syndrome [ROR (95% CI) = 6120.91 (5057.01-7408.64), n = 372], procedural pain [ROR (95% CI) = 54.86 (48.13-62.54), n = 234], idiopathic intracranial hypertension [ROR (95% CI) = 6.12 (2.29-16.33), n = 4], and hypokalemia [ROR (95% CI) = 2.02 (1.24-3.31), n = 16]. Additionally, transient deafness was identified as an unexpected and rare, yet severe, AE for nusinersen [ROR (95% CI) = 23.32 (8.71-62.44), n = 4]. Risdiplam exhibited 50 AEs exclusively, with notable idiosyncratic AEs including diarrhea [ROR (95% CI) = 4.55 (3.79-5.46), n = 121], fatigue [ROR (95% CI) = 2.03 (1.6-2.57), n = 70], photosensitivity reaction [ROR (95% CI) = 9.50 (4.25-21.13), n = 6], rash [ROR (95% CI) = 1.90 (1.36-2.67), n = 34], and [ROR (95% CI) = 4.3 (1.93-9.58), n = 6] in comparison with the other two drugs. Moreover, ileus [ROR (95% CI) = 11.11 (4.14-29.51), n = 4], gastrointestinal hemorrhage [ROR (95% CI) = 2.55 (1.15-5.69), n = 6], and hypoglycemic unconsciousness [ROR (95% CI) = 153.58 (62.98-374.54), n = 5] were rare but severe AEs associated with risdiplam. Onasemnogene abeparvovec had 143 exclusively identified AEs, with significant high signals for troponin I increase [ROR (95% CI) = 627.1 (492.2-798.99), n = 78], troponin T increase [ROR (95% CI) = 233.98 (153.29-357.15), n = 23], blood lactate dehydrogenase increase [ROR (95% CI) = 39.81 (28.88-54.87), n = 38], and transaminases increase [ROR (95% CI) = 36.88 (29.24-46.52), n = 73].

CONCLUSIONS

This study highlights the importance of monitoring injection-related injuries and transient deafness events in patients treated with nusinersen. For onasemnogene abeparvovec, careful monitoring for renal impairment, liver injury, and myocardial damage is necessary. Risdiplam requires attention to the potential risk of rare but severe gastrointestinal damage events and hypoglycemia. Importantly, risdiplam exhibited lower liver and renal toxicity, making it a potential consideration for patients with liver or renal insufficiency or for combined use with other drugs that possess high liver or renal toxicity. These findings can be a reference for drug selection and further prospective studies.

Clinical Phenotype of Pediatric and Adult Patients With Spinal Muscular Atrophy With Four SMN2 Copies: Are They Really All Stable?

OBJECTIVE

The aim of this study was to provide an overview of the clinical phenotypes associated with 4 SMN2 copies.

METHODS

Clinical phenotypes were analyzed in all the patients with 4 SMN2 copies as part of a nationwide effort including all the Italian pediatric and adult reference centers for spinal muscular atrophy (SMA).

RESULTS

The cohort includes 169 patients (102 men and 67 women) with confirmed 4 SMN2 copies (mean age at last follow-up = 36.9 ± 19 years). Six of the 169 patients were presymptomatic, 8 were classified as type II, 145 as type III (38 type IIIA and 107 type IIIB), and 8 as type IV. The remaining 2 patients were asymptomatic adults identified because of a familial case. The cross-sectional functional data showed a reduction of scores with increasing age. Over 35% of the type III and 25% of the type IV lost ambulation (mean age = 26.8 years ± 16.3 SD). The risk of loss of ambulation was significantly associated with SMA type (p < 0.0001), with patients with IIIB and IV less likely to lose ambulation compared to type IIIA. There was an overall gender effect with a smaller number of women and a lower risk for women to lose ambulation. This was significant in the adult (p = 0.009) but not in the pediatric cohort (p = 0.43).

INTERPRETATION

Our results expand the existing literature on natural history of 4 SMN2 copies confirming the variability of phenotypes in untreated patients, ranging from type II to type IV and an overall reduction of functional scores with increasing age. ANN NEUROL 2023;94:1126-1135.

Infusion reactions to adeno-associated virus (AAV)-based gene therapy: Mechanisms, diagnostics, treatment and review of the literature

The use of adeno-associated virus (AAV) vectors in gene therapy has demonstrated great potential in treating genetic disorders. However, infusion-associated reactions (IARs) pose a significant challenge to the safety and efficacy of AAV-based gene therapy. This review provides a comprehensive summary of the current understanding of IARs to AAV therapy, including their underlying mechanisms, clinical presentation, and treatment options. Toll-like receptor activation and subsequent production of pro-inflammatory cytokines are associated with IARs, stimulating neutralizing antibodies (Nabs) and T-cell responses that interfere with gene therapy. Risk factors for IARs include high titers of pre-existing Nabs, previous exposure to AAV, and specific comorbidities. Clinical presentation ranges from mild flu-like symptoms to severe anaphylaxis and can occur during or after AAV administration. There are no established guidelines for pre- and postadministration tests for AAV therapies, and routine laboratory requests are not standardized. Treatment options include corticosteroids, plasmapheresis, and supportive medications such as antihistamines and acetaminophen, but there is no consensus on the route of administration, dosage, and duration. This review highlights the inadequacy of current treatment regimens for IARs and the need for further research to improve the safety and efficacy of AAV-based gene therapy.

Gene therapy in spinal muscular atrophy

Infantile SMA is a neuromuscular disease caused by the motor neuron degeneration, depending on the age of appearance of clinical signs and the evolution of the disease, three types of decreasing severity have been defined. SMA is caused by mutations or deletions of the SMN1 gene and disease. Various therapies aimed at increasing SMN protein levels have been developed. Gene therapy is part of the therapeutic arsenal now available for the treatment of SMA under certain conditions. It uses the scAAV9 vector carrying a functional copy of SMN1 to restore SMN protein expression at the cellular level. Because the adeno-associated virus genome is maintained as it is an episome, a single intravenous administration is sufficient to producing a long-lasting therapeutic effect. The effectiveness of gene replacement therapy in patients with SMA has been demonstrated in various studies. It is now clear that treatment as early as possible provides better clinical results. However, this treatment must be carried out in a suitable medical environment, with close monitoring initially due to potentially serious side effects. In France, this treatment has been available since 2019. A national committee of experts involved in the treatment of pediatric SMA patients has established that pediatric patients with SMA decide on the indications for disease-modifying therapies (DMT) in children. The French Spinal Muscular Atrophy Registry (SMA France Registry) was established in January 2020. The registry includes all patients with genetically confirmed SMN1-related SMA. All patients treated with GT are systematically included in the registry. As of July 21, 2023: 72 patients with SMA have been treated with GT in France since June 2019. The arrival of new treatments reveals new clinical phenotypes of SMA which constitute a new management challenge. Treatment as early as possible is also a very important factor for a favorable outcome and calls for presymptomatic screening. However, the arrival of these new treatments, extremely expensive raises other socio-economic questions. © 2023 Published by Elsevier Masson SAS on behalf of French Society of Pediatrics.

RNA-Based Therapeutic Technology

RNA-based therapy has been an expanding area of clinical research since the COVID-19 outbreak. Often, its comparison has been made to DNA-based gene therapy, such as adeno-associated virus- and lentivirus-mediated therapy. These DNA-based therapies show persistent expression, with maximized therapeutic efficacy. However, accumulating data indicate that proper control of gene expression is occasionally required. For example, in cancer immunotherapy, cytokine response syndrome is detrimental for host animals, while excess activation of the immune system induces supraphysiological cytokines. RNA-based therapy seems to be a rather mild therapy, and it has room to fit unmet medical needs, whereas current DNA-based therapy has unclear issues. This review focused on RNA-based therapy for cancer immunotherapy, hematopoietic disorders, and inherited disorders, which have received attention for possible clinical applications.

Spinal Muscular Atrophy

OBJECTIVE

This article provides a comprehensive overview of the diagnostic assessment and treatment of individuals with spinal muscular atrophy (SMA) due to homozygous deletions of SMN1 .

LATEST DEVELOPMENTS

In recent years, most states have incorporated SMA in their newborn screening panel. To provide the earliest diagnosis possible after symptom onset, vigilance is needed for births in states without newborn screening for SMA and when compound heterozygotes are missed by newborn screening programs. Supportive care for respiratory, nutritional, and orthopedic health impacts outcomes and is the cornerstone of care. Adaptive equipment, including assistive home technology, enables affected individuals to gain autonomy in their daily activities. Pharmacologic treatments approved by the US Food and Drug Administration (FDA) include three drugs that increase deficient survival motor neuron protein levels through SMN1 - or SMN2 - directed pathways: nusinersen, onasemnogene abeparvovec, and risdiplam. Efficacy for these trials was measured in event-free survival (survival without the need for permanent ventilation) and gains in functional motor outcomes. Earlier treatment is most effective across all treatments.

ESSENTIAL POINTS

The diagnostic and therapeutic landscapes for SMA have seen dramatic advancements in recent years, improving prognosis. Optimized supportive care remains essential, and vigilance is needed to define the new natural history of this disease.

Onasemnogene abeparvovec gene replacement therapy for the treatment of spinal muscular atrophy: a real-world observational study

Spinal muscular atrophy (SMA) is a genetically inherited recessive neuromuscular disease that causes muscular atrophy and weakness. Onasemnogene abeparvovec (formerly AVXS-101, Zolgensma®, Novartis) is a targeted therapy approved to treat patients with SMA in >40 countries worldwide. This study describes the clinical efficacy and tolerability of gene replacement therapy with onasemnogene abeparvovec over a 3-month period in 9 SMA type 1 patients aged 1.7-48 months, with 7 patients on stable nusinersen (i.e., had received all four nusinersen loading doses before inclusion in this study). Liver function (alanine aminotransferase, aspartate aminotransferase, total bilirubin), troponin I, platelet counts, creatinine levels, and motor function (CHOP-INTEND) were monitored. For the seven patients on stable nusinersen, the median baseline CHOP-INTEND score increased significantly during nusinersen treatment (Wilcoxon signed-rank test p = 0.018) and at 3 months after switching to onasemnogene abeparvovec (Wilcoxon signed-rank test p = 0.0467). We also identified two patients who responded poorly to nusinersen but showed the largest increase in baseline CHOP-INTEND scores at 1 and 3 months after switching, which could suggest that poor responders to nusinersen may respond favorably to onasemnogene abeparvovec. No unknown adverse events occurred. One patient developed moderate/severe thrombocytopenia 1 week after onasemnogene abeparvovec administration that resolved after treatment. Our study suggests the possibility of a change in the dynamic of CHOP-INTEND for patients who respond poorly to nusinersen after switching therapy to onasemnogene abeparvovec. Alternatively, patient age at treatment initiation may impact the response to onasemnogene abeparvovec. Testing in larger patient populations must be undertaken to assess the plausibility of these hypotheses.

Expanding the Availability of Onasemnogene Abeparvovec to Older Patients: The Evolving Treatment Landscape for Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by mutations in the survival of motor neuron 1 (SMN1) gene, which leads to a reduced level in the SMN protein within cells. Patients with SMA suffer from a loss of alpha motor neurons in the spinal cord leading to skeletal muscle atrophy in addition to deficits in other tissues and organs. Patients with severe forms of the disease require ventilator assistance and typically succumb to the disease due to respiratory failure. Onasemnogene abeparvovec is an adeno-associated virus (AAV)-based gene therapeutic that has been approved for infants and young children with SMA, and it is delivered through intravenous administration using a dose based on the weight of the patient. While excellent outcomes have been observed in treated patients, the greater viral dose necessary to treat older children and adults raises legitimate safety concerns. Recently, onasemnogene abeparvovec use was investigated in older children through a fixed dose and intrathecal administration, a route that provides a more direct delivery to affected cells in the spinal cord and central nervous system. The promising results observed in the STRONG trial may support approval of onasemnogene abeparvovec for a greater proportion of patients with SMA.

Early Development of Spinal Deformities in Children Severely Affected with Spinal Muscular Atrophy after Gene Therapy with Onasemnogene Abeparvovec-Preliminary Results

Spinal muscular atrophy (SMA) is a rare genetic disorder, with the most common form being 5q SMA. Survival of children with severe SMA is poor, yet major advances have been made in recent years in pharmaceutical treatment, such as gene-therapy, which has improved patient survival. Therefore, clinical problems, such as the development of spinal deformities in these genetically treated SMA children represent an unknown challenge in clinical work. In a retrospective case series, the development of spinal deformities was analyzed in 16 SMA children (9 male, 7 female) treated with onasemnogene abeparvovec in two institutions during the years 2020 to 2022. Ten out of sixteen patients had a significant kyphosis, and nine out of sixteen patients had significant scoliosis, with the mean curvature angles of 24 ± 27° for scoliosis, and 69 ± 15° for kyphosis. Based on these preliminary data, it can be assumed that early-onset kyphosis presents a clinical challenge in gene-therapy-treated SMA children. Larger datasets with longer follow-up times need to be collected in order to verify these preliminary observations.

Parkinson's disease therapy: what lies ahead?

The worldwide prevalence of Parkinson's disease (PD) has been constantly increasing in the last decades. With rising life expectancy, a longer disease duration in PD patients is observed, further increasing the need and socioeconomic importance of adequate PD treatment. Today, PD is exclusively treated symptomatically, mainly by dopaminergic stimulation, while efforts to modify disease progression could not yet be translated to the clinics. New formulations of approved drugs and treatment options of motor fluctuations in advanced stages accompanied by telehealth monitoring have improved PD patients care. In addition, continuous improvement in the understanding of PD disease mechanisms resulted in the identification of new pharmacological targets. Applying novel trial designs, targeting of pre-symptomatic disease stages, and the acknowledgment of PD heterogeneity raise hopes to overcome past failures in the development of drugs for disease modification. In this review, we address these recent developments and venture a glimpse into the future of PD therapy in the years to come.

Onasemnogene abeparvovec in spinal muscular atrophy: predictors of efficacy and safety in naïve patients with spinal muscular atrophy and following switch from other therapies

Background

Efficacy and safety of onasemnogene abeparvovec (OA) for Spinal Muscular Atrophy infants under 7 months and <8.5 kg has been reported in clinical trials. This study examines efficacy and safety predictors in a wide age (22 days-72 months) and weight (3.2-17 kg) range, also including patients previously treated with other drugs.

Methods

46 patients were treated for 12 months between January 2020 and March 2022. Safety profile was also available for another 21 patients with at least 6 month follow-up after OA infusion. 19/67 were treatment naïve when treated with OA. Motor function was measured with the CHOP-INTEND.

Findings

CHOP-INTEND changes varied among age groups. Baseline score and age at OA treatment best predicted changes. A mixed model post-hoc analysis showed that in patients treated before the age of 24 months the CHOP-INTEND changes were already significant 3 months after OA while in those treated after the age of 24 months the difference was only significant 12 months after OA. Adverse events occurred in 51/67. The risk for elevated transaminases serum levels was higher in older patients. This was also true for weight and for pre-treatment with nusinersen when analysed individually. A binomial negative regression analysis showed that only age at OA treatment had a significant effect on the risk of elevated transaminases.

Interpretation

Our paper describes OA 12-month follow-up showing efficacy across various age and weight groups not targeted by clinical trials. The study identifies prognostic factors for safety and efficacy in treatment selection.

Funding

None.

Real-Life Outcome After Gene Replacement Therapy for Spinal Muscular Atrophy: A Multicenter Experience

BACKGROUND

Onasemnogene abeparvovec-xioi (OA) has been available since 2019 as a gene replacement therapy for individuals with spinal muscular atrophy (SMA) under age two years. We aim to expand upon the sparse knowledge about its safety and clinical efficacy.

METHODS

The clinical outcome data of all the individuals with SMA who were treated with gene therapy in four tertiary hospitals in Israel were retrieved and analyzed.

RESULTS

The study participants included 25 individuals who received the gene therapy between age 11 days and 23 months and whose median follow-up duration was 18.0 (interquartile range [IQR], 12.4 to 18.3) months. Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scores increased by a median (IQR) of 13 (8 to 20) points at the last follow-up compared with baseline. None of the patients experienced regression in motor abilities after gene therapy, which was generally well tolerated. There was gradual improvement in motor function, especially among presymptomatic patients (P ≤ 0.001) whose disease duration was shorter (≤8 months) before receiving gene therapy (P ≤ 0.001) and who did not experience recurrent infections and illnesses in the months following treatment (P ≤ 0.001).

CONCLUSIONS

OA was well tolerated and led to favorable functional motor outcomes at six to 24 months after treatment initiation. Better progress in motor function was observed in individuals who received OA earlier and who were presymptomatic, irrespective of the SMN2 copy number or type. Our results further strengthen the clinical efficacy of OA and reinforce the importance of early recognition of SMA via newborn screening programs.

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

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

[Update on drug treatment of spinal muscular atrophy]

BACKGROUND

The 5q-associated spinal muscular atrophy (SMA) is a hereditary motor neuron disease leading to progressive tetraplegia, often involving the bulbopharyngeal and respiratory muscle groups. The disease usually manifests in early childhood and, if untreated, is progressive throughout life and associated with numerous complications depending on the severity. Since 2017, genetically based therapeutic mechanisms are now available that correct the causative deficiency of survival motor neuron (SMN) protein and lead to significant modifications in disease progression. As the number of treatment options increases, the question of which patient is suitable for which treatment also arises.

OBJECTIVE

This review article provides an update on the current treatment strategies for SMA in children and adults.

AAV vectors applied to the treatment of CNS disorders: Clinical status and challenges

In recent years, adeno-associated virus (AAV) has become the most important vector for central nervous system (CNS) gene therapy. AAV has already shown promising results in the clinic, for several CNS diseases that cannot be treated with drugs, including neurodegenerative diseases, neuromuscular diseases, and lysosomal storage disorders. Currently, three of the four commercially available AAV-based drugs focus on neurological disorders, including Upstaza for aromatic l-amino acid decarboxylase deficiency, Luxturna for hereditary retinal dystrophy, and Zolgensma for spinal muscular atrophy. All these studies have provided paradigms for AAV-based therapeutic intervention platforms. AAV gene therapy, with its dual promise of targeting disease etiology and enabling 'long-term correction' of disease processes, has the advantages of immune privilege, high delivery efficiency, tissue specificity, and cell tropism in the CNS. Although AAV-based gene therapy has been shown to be effective in most CNS clinical trials, limitations have been observed in its clinical applications, which are often associated with side effects. In this review, we summarized the therapeutic progress, challenges, limitations, and solutions for AAV-based gene therapy in 14 types of CNS diseases. We focused on viral vector technologies, delivery routes, immunosuppression, and other relevant clinical factors. We also attempted to integrate several hurdles faced in clinical and preclinical studies with their solutions, to seek the best path forward for the application of AAV-based gene therapy in the context of CNS diseases. We hope that these thoughtful recommendations will contribute to the efficient translation of preclinical studies and wide application of clinical trials.

Treatment of spinal muscular atrophy with Onasemnogene Abeparvovec in Switzerland: a prospective observational case series study

BACKGROUND

Spinal muscular atrophy (SMA) is a rare neuromuscular disorder leading to early death in the majority of affected individuals without treatment. Recently, targeted treatment approaches including Onasemnogene Abeparvovec (OA) were introduced. This study describes the first real-world experience with OA in Switzerland.

METHODS

Prospective observational case series study using data collected within the Swiss Registry for Neuromuscular Disorders from SMA patients treated with OA. Development of motor, bulbar and respiratory function, appearance of scoliosis, and safety data (platelet count, liver function, and cardiotoxicity) were analyzed.

RESULTS

Nine individuals were treated with OA and followed for 383 ± 126 days: six SMA type 1 (of which two with nusinersen pretreatment), one SMA type 2, and two pre-symptomatic individuals. In SMA type 1, CHOP Intend score increased by 28.1 from a mean score of 20.5 ± 7.6 at baseline. At end of follow-up, 50% of SMA type 1 patients required nutritional support and 17% night-time ventilation; 67% developed scoliosis. The SMA type 2 patient and two pre-symptomatically treated individuals reached maximum CHOP Intend scores. No patient required adaptation of the concomitant prednisolone treatment, although transient decrease of platelet count and increase of transaminases were observed in all patients. Troponin-T was elevated prior to OA treatment in 100% and showed fluctuations in 57% thereafter.

CONCLUSIONS

OA is a potent treatment for SMA leading to significant motor function improvements. However, the need for respiratory and especially nutritional support as well as the development of scoliosis must be thoroughly evaluated in SMA type 1 patients even in the short term after OA treatment.

[Introduction to Gene Therapy]

After many years of research and numerous setbacks, there are now undeniable success stories of gene therapies, namely the direct modification of genetic information on the DNA or RNA level. Both "ex vivo" strategies, i. e. the genetic manipulation of patient cells in a dish, as well as "in vivo" approaches are being used successfully. In addition to the supplementation of defective genes, the use of the CRISPR-Cas9 system to alter nuclear DNA sequences and the sequence-specific interference with the transcriptional process on the RNA level can be designated as gene therapies in a broad sense.

Safety and efficacy of gene therapy with onasemnogene abeparvovec in the treatment of spinal muscular atrophy: A systematic review and meta-analysis

Spinal muscular atrophy (SMA) is an autosomal recessive hereditary disease which leads to progressive muscle weakness and atrophy. Our systematic review and meta-analysis aims to explore the efficacy and safety of onasemnogene abeparvovec in SMA patients. We searched PubMed, EMBASE, Web of Science and Cochrane through April 2022. Ten reports enrolling 250 SMA patients were included. CHOP INTEND and motor-milestone significant improvements were detected at both short- and long-term follow-up. Common adverse events included pyrexia, vomiting, thrombocytopenia and elevated aminotransferases. Thrombocytopenia (79.3%, 95%CI: 65.8~90.5) and elevated aminotransferases (71.7%, 95%CI: 62.5~80.1) were more common in SMA patients aged older than 8 months. Despite the paucity of randomized control trial data and low quality of evidence to establish the safety and efficacy of onasemnogene abeparvovec in the treatment of SMA, the data suggest that it is a valuable option for patients with this condition.

Flexible endoscopic evaluation of swallowing in children with type 1 spinal muscular atrophy

PURPOSE

This study aimed to report on implementing flexible endoscopic evaluation of swallowing (FEES) in infants and toddlers with type 1 spinal muscular atrophy (SMA). In addition, a comparison of FEES results and clinical scores was carried out.

METHODS

A prospective pilot study was conducted including ten symptomatic children with SMA type 1 (two SMN2 copies). They started treatment with one of the three currently approved therapies for SMA at a median age of 3.8 months (range 0.7-8.9). FEES was performed according to a standard protocol using Penetration-Aspiration Scale (PAS) and Murray Secretion Scale as a primary outcome. The Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) for motor function, Neuromuscular Disease Swallowing Status Scale (NdSSS), Oral and Swallowing Abilities Tool (OrSAT), and single clinical swallowing-related parameters were also assessed.

RESULTS

Distinct swallowing disorders were already evident in eight children at inclusion. The most common findings from FEES were pharyngeal secretion pooling, penetration, and aspiration of saliva and food as well as delayed initiation of swallowing. Despite an average increase in motor function, no comparable improvement was found in swallowing function. None of the surveyed clinical scores showed a significant dependence on PAS in a mixed linear model.

CONCLUSIONS

Valuable information regarding the status of dysphagia can be gathered endoscopically, particularly concerning secretion management and when oral intake is limited. Currently available clinical tools for children with type 1 may represent a change in nutritional status but are not yet mature enough to conclude swallowing ability. Further development is still required.

A systematic review of adeno-associated virus gene therapies in neurology: the need for consistent safety monitoring of a promising treatment

Adeno-associated virus (AAV) gene therapies are generating much excitement in the rare disease field, particularly for previously untreatable neurological conditions. Efficacy has been claimed for several gene therapy products and the number of trials is rapidly increasing. However, reports of severe treatment-related adverse reactions are emerging, including death. There is still insufficient knowledge about their aetiology, prevention and treatment. We therefore undertook to systematically review publicly available data on AAV gene therapies in order to collate existing information on both safety and efficacy. Here, we review emerging efficacy reports of these novel therapies, many of which show promise. We also collate an increasing number of adverse reactions. Overwhelmingly, these results make a case for unified reporting of adverse events. This is likely to be critical for improving the safety of these promising treatments.

Real-world Associations of US Cystic Fibrosis Newborn Screening Programs With Nutritional and Pulmonary Outcomes

IMPORTANCE

Newborn screening (NBS) for cystic fibrosis (CF) has been universal in the US since 2010, but its association with clinical outcomes is unclear.

OBJECTIVE

To describe the real-world effectiveness of NBS programs for CF in the US on outcomes up to age 10 years.

DESIGN, SETTING, AND PARTICIPANTS

This was a retrospective cohort study using CF Foundation Patient Registry data from January 1, 2000, to December 31, 2018. The staggered implementation of NBS programs by state was used to compare longitudinal outcomes among children in the same birth cohort born before vs after the implementation of NBS for CF in their state of birth. Participants included children with an established diagnosis of CF born between January 1, 2000, to December 31, 2018, in any of the 44 states that implemented NBS for CF between 2003 and 2010. Data were analyzed from October 5, 2020, to April 22, 2022.

EXPOSURES

Birth before vs after the implementation of NBS for CF in the state of birth.

MAIN OUTCOMES AND MEASURES

Longitudinal trajectory of height and weight percentiles from diagnosis, lung function (forced expiratory volume in 1 second, [FEV1] percent predicted) from age 6 years, and age at initial and chronic infection with Pseudomonas aeruginosa using linear mixed-effects and time-to-event models adjusting for birth cohort and potential confounders.

RESULTS

A total of 9571 participants (4713 female participants [49.2%]) were eligible for inclusion, with 4510 (47.1%) in the pre-NBS cohort. NBS was associated with higher weight and height percentiles in the first year of life (weight, 6.0; 95% CI, 3.1-8.4; height, 6.6; 95% CI, 3.8-9.3), but these differences decreased with age. There was no association between NBS and FEV1 at age 6 years, but the percent-predicted FEV1 did increase more rapidly with age in the post-NBS cohort. NBS was associated with older age at chronic P aeruginosa infection (hazard ratio, 0.69; 95% CI, 0.54-0.89) but not initial P aeruginosa infection (hazard ratio, 0.88; 95% CI, 0.77-1.01).

CONCLUSIONS AND RELEVANCE

NBS for CF in the US was associated with improved nutritional status up to age 10 years, a more rapid increase in lung function, and delayed chronic P aeruginosa infection. In the future, as highly effective modulator therapies become available for infants with CF, NBS will allow for presymptomatic initiation of these disease-modifying therapies before irreversible organ damage.

What's new and what's next for gene therapy in Pompe disease?

INTRODUCTION

Pompe disease is an autosomal recessive disorder caused by a deficiency of acid-α-glucosidase (GAA), an enzyme responsible for hydrolyzing lysosomal glycogen. A lack of GAA leads to accumulation of glycogen in the lysosomes of cardiac, skeletal, and smooth muscle cells, as well as in the central and peripheral nervous system. Enzyme replacement therapy has been the standard of care for 15 years and slows disease progression, particularly in the heart, and improves survival. However, there are limitations of ERT success, which gene therapy can overcome.

AREAS COVERED

Gene therapy offers several advantages including prolonged and consistent GAA expression and correction of skeletal muscle as well as the critical CNS pathology. We provide a systematic review of the preclinical and clinical outcomes of adeno-associated viral mediated gene therapy and alternative gene therapy strategies, highlighting what has been successful.

EXPERT OPINION

Although the preclinical and clinical studies so far have been promising, barriers exist that need to be addressed in gene therapy for Pompe disease. New strategies including novel capsids for better targeting, optimized DNA vectors, and adjuctive therapies will allow for a lower dose, and ameliorate the immune response.

Onasemnogene Abeparvovec: A Review in Spinal Muscular Atrophy

Onasemnogene abeparvovec (Zolgensma®) is a gene therapy approved for the treatment of spinal muscular atrophy (SMA). Administered as a one-time intravenous infusion, onasemnogene abeparvovec uses the adeno-associated virus vector to deliver a functional copy of the human survival motor neuron (SMN) gene to motor neuron cells. SMN1 encodes survival motor neuron protein, which is responsible for the maintenance and function of motor neurons. In clinical trials, onasemnogene abeparvovec improved event-free survival, motor function and motor milestone outcomes in patients with SMA, with these improvements maintained over the longer term (up to a median of ≈ 5 years). Onasemnogene abeparvovec was also associated with rapid age-appropriate achievement of motor milestones and improvements in motor function in children with pre-symptomatic SMA, indicating the benefit of early treatment. Onasemnogene abeparvovec was generally well tolerated. Hepatotoxicity is a known risk that can generally be mitigated with prophylactic prednisolone. In conclusion, onasemnogene abeparvovec represents an important treatment option for patients with SMA, particularly when initiated early in the course of the disease.

Experience and Perspectives in the US on the Evolving Treatment Landscape in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a rare, progressive neuromuscular disorder that, until recently, was the most common inherited cause of infant mortality. Since 2016, three disease-modifying therapies have emerged, nusinersen, onasemnogene abeparvovec-xioi, and risdiplam, leading to a transformation in the SMA treatment landscape, changes in disease trajectories, and a profound impact on clinical care. This environment poses a challenge to making informed treatment decisions, including initial treatment choice, treatment changes, and potential use of combination therapies as new data emerge. To better understand factors that influence physician-patient decision-making, a roundtable discussion was convened by Biogen (sponsor) with a panel of four US SMA experts. This report shares the panel’s opinions and clinical experiences, with the goals of helping clinicians and people with SMA and their families to better understand the factors influencing real-world treatment decisions and stimulating a broader discussion in the SMA community. The panelists highlighted that patients are often heavily involved in treatment decisions, and physicians must be aware of current data to guide patients in making the best decisions. Thus, in the absence of data from head-to-head treatment comparisons, physicians’ roles include reviewing treatment options and describing what is known of the benefits, challenges, and potential side effects of each therapy with patients and families. For infants and young children, the panelists expressed a sense of urgency for early intervention to minimize motor function loss, whereas the goal for adults is long-term disease stabilization. In the panelists’ experience, factors that influence patients’ decisions to change to an alternative therapy include convenience, administration route, novelty of therapy, and hope for improved function, while reasons for returning to a previous therapy include a perception of decreased efficacy and side effects. Ongoing clinical trials and analyses of real-world experiences should further inform treatment decisions and optimize patient outcomes.