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

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

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

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.

Getting Wheels: development and evaluation of a psychoeducational resource for parents of children with a neuromuscular condition following recommendation of wheelchair equipment

PURPOSE

Access to credible information can facilitate parental engagement in wheelchair prescription for their child with a neuromuscular condition (NMC). In this study, we developed and evaluated acceptability, perceived usefulness and emotional responses to a psychoeducational booklet for parents of children with a NMC.

METHODS

Australian parents of children who had been recommended a wheelchair and clinicians caring for children with NMCs were invited to evaluate the booklet, Getting Wheels. The booklet included 11 chapters, each covering distinct aspects of wheelchair prescription and supportive care. Participants completed one online survey including validated and study-specific measures.

RESULTS

Twenty-seven parents (71% response rate, 78% mothers) and nine clinicians (90% response rate, 89% women) participated. All parents endorsed the booklet as addressing their information and support needs, and 93% agreed it would help parents engage in the wheelchair prescription process. All clinicians endorsed the booklet as addressing parents' information and support needs and agreed they could use the booklet in clinical practice.

CONCLUSIONS

Parents and clinicians rate Getting Wheels as acceptable for use in the context of wheelchair recommendation for children with a neuromuscular condition. Next steps include prospective examination of booklet use in clinical practice and adaptation to culturally and linguistically diverse populations.Implications for rehabilitationThe co-designed "Getting Wheels" booklet provides tailored information for use in the context of wheelchair recommendation for children with a neuromuscular condition.The emotions elicited throughout wheelchair prescription endorse the need for integrated psychosocial multidisciplinary care to improve access and support the ongoing emotional needs of this population.Parents of children who receive wheelchair recommendation between zero and two years require greater support from clinicians regarding their thoughts and feelings about wheelchair prescription.Parents of children with a neuromuscular condition and treating clinicians support provision of a tailored psychoeducational resource when a child is recommended a wheelchair.

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.

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.