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

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.

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

Purpose

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

Methods

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

Results

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

Conclusion

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

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.

Treatment of Symptomatic Spinal Muscular Atrophy with Nusinersen: A Prospective Longitudinal Study on Scoliosis Progression

Background

Nusinersen treatment has demonstrated efficacy in improving clinical outcomes for spinal muscular atrophy (SMA), yet its impact on scoliosis progression remains unclear.

Objective

This study aimed to assess the progression of scoliosis in pediatric patients with SMA undergoing nusinersen treatment.

Methods

In this prospective study, data were systematically collected from Hong Kong pediatric SMA patients receiving nusinersen between 2018 and 2023. All patients had longitudinal radiographic studies pre-nusinersen, and at half-yearly or yearly intervals during treatment based on the scoliosis severity. Motor function evaluations were conducted pre-nusinersen, and after starting treatment at 6- and 12-month intervals.

Results

Twenty-three patients ((SMA type 1 (SMA1) = 8, SMA type 2 (SMA2) = 7, SMA type 3 (SMA3) = 8)) with a median age of 5.8 years (range: 0.4-17.5 years) at nusinersen initiation, and median follow-up duration of 3.4 years (range: 1.1-5.2 years) were included. During the study period, motor scores remained stable or improved in 83% of patients. However, scoliosis progressed across all subtypes, with mean annual progression rates of 5.2, 11.9, and 3.6 degrees in SMA1, SMA2, and SMA3 respectively. Patients initiating nusinersen between ages 5 and 11 years exhibited the most rapid progression, with rates of 11.8, 16.5, and 7.3 degrees per year in SMA1, SMA2, and SMA3 respectively. Positive correlations were observed between the difference in CHOP-INTEND score post-nusinersen and scoliosis progression in SMA1 (rs = 0.741, p = 0.041). Conversely, negative correlations were found between the difference in HFMSE score post-nusinersen and scoliosis progression in SMA2 (rs =-0.890, p = 0.012) and SMA3 (rs =-0.777, p = 0.028).

Conclusions

This study reveals that nusinersen treatment in symptomatic pediatric SMA patients with motor improvement is linked to increased scoliosis progression in SMA1, whereas it is associated with decreased progression in SMA2 and SMA3. Age, baseline Cobb angle, and motor milestone improvement are influential factors in scoliosis progression.

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.

Consensus from the Brazilian Academy of Neurology for the diagnosis, genetic counseling, and use of disease-modifying therapies in 5q spinal muscular atrophy

Spinal muscular atrophy linked to chromosome 5 (SMA-5q) is an autosomal recessive genetic disease caused by mutations in the SMN1. SMA-5q is characterized by progressive degeneration of the spinal cord and bulbar motor neurons, causing severe motor and respiratory impairment with reduced survival, especially in its more severe clinical forms. In recent years, highly effective disease-modifying therapies have emerged, either acting by regulating the splicing of exon 7 of the SMN2 gene or adding a copy of the SMN1 gene through gene therapy, providing a drastic change in the natural history of the disease. In this way, developing therapeutic guides and expert consensus becomes essential to direct the use of these therapies in clinical practice. This consensus, prepared by Brazilian experts, aimed to review the main available disease-modifying therapies, critically analyze the results of clinical studies, and provide recommendations for their use in clinical practice for patients with SMA-5q. This consensus also addresses aspects related to diagnosis, genetic counseling, and follow-up of patients under drug treatment. Thus, this consensus provides valuable information regarding the current management of SMA-5q, helping therapeutic decisions in clinical practice and promoting additional gains in outcomes.

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.

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.