Ethical Perspectives on Treatment Options with Spinal Muscular Atrophy Patients

Patients' Perceptions of Nusinersen Effects According to Their Responder Status

Background and Objective: Patients with spinal muscular atrophy (SMA) treated with a disease-modifying therapy (DMT) are often classified as responders or non-responders based on the attainment of a specific improvement threshold on validated functional scales. This categorization may significantly impact treatment reimbursement in some countries. The aim of this research is to evaluate the perception of treatments and their benefit by patients considered as responders or non-responders. Methods: In this non-commercial multicenter study, 99 post-symptomatically treated SMA type I-III patients with a median age of 11.2 (0.39-57.4) years at treatment initiation were stratified into three groups based on their treatment outcomes, i.e., those exhibiting clinically significant improvement (N = 41), those with non-clinically significant improvement (N = 18), or those showing no improvement (N = 40). Fifteen months after treatment, the initiation patients or patients' caregivers were assessed using a patient-rated scoring system based on the Patient Global Impression of Change (PGIC) scale, comprising 22 questions targeting important aspects and tasks in the daily life of patients with SMA. Results: We found no statistical difference in the patient perception of treatment benefits in 17 out of 22 domains across patient groups. Conclusions: Our results suggest that functional motor scales do not recapitulate patients' and patients' caregivers' experience of the effect of nusinersen treatment in SMA.

A consensus survey of neurologists and clinical geneticists on spinal muscular atrophy treatment in Singapore

Just a decade ago, spinal muscular atrophy (SMA) was considered a debilitating, progressive neuromuscular disease that inevitably led to chronic disability and a shortened lifespan. Now, it is treatable with nusinersen, onasemnogene abeparvovec (OAV) and risdiplam—the 3 disease-modifying drugs approved by the US Food and Drug Administration, the European Medicines Agency and most recently, the Health Science Authority in Singapore.1 Clinical trials and real-world data have consistently shown improvement in motor milestones for all 3 drugs, especially if introduced early in the disease course.2-4 More significantly, presymptomatic treatment has enabled age-appropriate development of motor milestones, leading to improved respiratory, orthopaedic and nutritional outcomes.

Hepatocyte-intrinsic SMN deficiency drives metabolic dysfunction and liver steatosis in spinal muscular atrophy

Spinal Muscular Atrophy (SMA) is typically characterized as a motor neuron disease, but extra-neuronal phenotypes are present in almost every organ in severely affected patients and animal models. Extra-neuronal phenotypes were previously underappreciated as patients with severe SMA phenotypes usually died in infancy; however, with current treatments for motor neurons increasing patient lifespan, impaired function of peripheral organs may develop into significant future comorbidities and lead to new treatment-modified phenotypes. Fatty liver is seen in SMA animal models , but generalizability to patients and whether this is due to hepatocyte-intrinsic Survival Motor Neuron (SMN) protein deficiency and/or subsequent to skeletal muscle denervation is unknown. If liver pathology in SMA is SMN-dependent and hepatocyte-intrinsic, this suggests SMN repleting therapies must target extra-neuronal tissues and motor neurons for optimal patient outcome. Here we showed that fatty liver is present in SMA and that SMA patient-specific iHeps were susceptible to steatosis. Using proteomics, functional studies and CRISPR/Cas9 gene editing, we confirmed that fatty liver in SMA is a primary SMN-dependent hepatocyte-intrinsic liver defect associated with mitochondrial and other hepatic metabolism implications. These pathologies require monitoring and indicate need for systematic clinical surveillance and additional and/or combinatorial therapies to ensure continued SMA patient health.

Life-Saving Treatments for Spinal Muscular Atrophy: Global Access and Availability

Background and Objectives

Spinal muscular atrophy (SMA) is a neurodegenerative disorder manifesting with progressive muscle weakness and atrophy. SMA type 1 used to be fatal within the first 2 years of life, but is now treatable with therapies targeting splicing modification and gene replacement. Nusinersen, risdiplam, and onasemnogene abeparvovec-xioi improve survival, motor strength, endurance, and ability to thrive, allowing many patients to potentially attain a normal life; all have been recently approved by major regulatory agencies. Although these therapies have revolutionized the world of SMA, they are associated with a high economic burden, and access to these therapies is limited in some countries. The primary objective of this study was to compare the availability and implementation of treatment of SMA from different regions of the world.

Methods

In this qualitative study, we surveyed health care providers from 21 countries regarding their experiences caring for patients with SMA. The main outcome measures were provider survey responses on newborn screening, drug availability/access, barriers to treatment, and related questions.

Results

Twenty-four providers from 21 countries with decades of experience (mean 26 years) in treating patients with SMA responded to the survey. Nusinersen was the most available therapy for SMA. Our survey showed that while genetic testing is usually available, newborn screening is still unavailable in many countries. The provider-reported treatment cost also varied between countries, and economic burden was a major barrier in treating patients with SMA.

Discussion

Overall, this survey highlights the global inequality in managing patients with SMA. The spread of newborn screening is essential in ensuring improved access to care for patients with SMA. With the advancement of neurotherapeutics, more genetic diseases will soon be treatable, and addressing the global inequality in clinical care will require novel approaches to mitigate such inequality in the future.

Spinal Muscular Atrophy Treatment: The MTOR Regulatory Intervention

Spinal muscular atrophy (SMA) is a hereditary disorder affecting neurons and muscles, resulting in muscle weakness and atrophy. Most SMA cases are diagnosed during infancy or early childhood, the most common inherited cause of infant mortality without treatment. Still, SMA might appear at older ages with milder symptoms. SMA patients demonstrate progressive muscle waste, movement problems, tremors, dysphagia, bone and joint deformations, and breathing difficulties. The mammalian target of rapamycin (mTOR), the mechanistic target of rapamycin, is a member of the phosphatidylinositol 3-kinase-related kinase family of protein kinases encoded by the mTOR gene in humans. The mTOR phosphorylation, deregulation, and autophagy have shown dissimilarity amongst SMA cell types. Therefore, exploring the underlying molecular process in SMA therapy could provide novel insights and pave the way for finding new treatment options. This paper provides new insight into the possible modulatory effect of mTOR/ autophagy in SMA management.

Gene therapy-based strategies for spinal muscular atrophy-an Asia-Pacific perspective

Onasemnogene abeparvovec has been life-changing for children with spinal muscular atrophy (SMA), signifying the potential and progress occurring in gene- and cell-based therapies for rare genetic diseases. Hence, it is important that clinicians gain knowledge and understanding in gene therapy-based treatment strategies for SMA. In this review, we describe the development and translation of onasemnogene abeparvovec from clinical trials to healthcare practice and share knowledge on the facilitators and barriers to implementation. Rapid and accurate SMA diagnosis, awareness, and education to safely deliver gene therapy to eligible patients and access to expertise in multidisciplinary management for neuromuscular disorders are crucial for health system readiness. Early engagement and intersectoral collaboration are required to surmount complex logistical processes and develop policy, governance, and accountability. The collection and utilisation of real-world evidence are also an important part of clinical stewardship, informing ongoing improvements to care delivery and access. Additionally, a research-enabled clinical ecosystem can expand scientific knowledge and discovery to optimise future therapies and magnify health impacts. Important ethical, equity, economic, and sustainability issues are evident, for which we must connect globally.

Identification of potential pathways and biomarkers linked to progression in ALS

OBJECTIVE

To identify potential diagnostic and prognostic biomarkers for clinical management and clinical trials in amyotrophic lateral sclerosis.

METHODS

We analysed proteomics data of ALS patient-induced pluripotent stem cell-derived motor neurons available through the AnswerALS consortium. After stratifying patients using clinical ALSFRS-R and ALS-CBS scales, we identified differentially expressed proteins indicative of ALS disease severity and progression rate as candidate ALS-related and prognostic biomarkers. Pathway analysis for identified proteins was performed using STITCH. Protein sets were correlated with the effects of drugs using the Connectivity Map tool to identify compounds likely to affect similar pathways. RNAi screening was performed in a Drosophila TDP-43 ALS model to validate pathological relevance. A statistical classification machine learning model was constructed using ridge regression that uses proteomics data to differentiate ALS patients from controls.

RESULTS

We identified 76, 21, 71 and 1 candidate ALS-related biomarkers and 22, 41, 27 and 64 candidate prognostic biomarkers from patients stratified by ALSFRS-R baseline, ALSFRS-R progression slope, ALS-CBS baseline and ALS-CBS progression slope, respectively. Nineteen proteins enhanced or suppressed pathogenic eye phenotypes in the ALS fly model. Nutraceuticals, dopamine pathway modulators, statins, anti-inflammatories and antimicrobials were predicted starting points for drug repurposing using the connectivity map tool. Ten diagnostic biomarker proteins were predicted by machine learning to identify ALS patients with high accuracy and sensitivity.

INTERPRETATION

This study showcases the powerful approach of iPSC-motor neuron proteomics combined with machine learning and biological confirmation in the prediction of novel mechanisms and diagnostic and predictive biomarkers in ALS.

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.

Spinal muscular atrophy

Spinal muscular atrophy (SMA) is a neurodegenerative disorder caused by mutations in SMN1 (encoding survival motor neuron protein (SMN)). Reduced expression of SMN leads to loss of α-motor neurons, severe muscle weakness and often early death. Standard-of-care recommendations for multidisciplinary supportive care of SMA were established in the past few decades. However, improved understanding of the pathogenetic mechanisms of SMA has led to the development of different therapeutic approaches. Three treatments that increase SMN expression by distinct molecular mechanisms, administration routes and tissue biodistributions have received regulatory approval with others in clinical development. The advent of the new therapies is redefining standards of care as in many countries most patients are treated with one of the new therapies, leading to the identification of emerging new phenotypes of SMA and a renewed characterization of demographics owing to improved patient survival.