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Farrar MA, Calotes-Castillo L, De Silva R, Barclay P, Attwood L, Cini J, Ferrie M, Kariyawasam DS. Gene therapy-based strategies for spinal muscular atrophy-an Asia-Pacific perspective. Mol Cell Pediatr 2023; 10:17. [PMID: 37964159 PMCID: PMC10645685 DOI: 10.1186/s40348-023-00171-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 11/07/2023] [Indexed: 11/16/2023] Open
Abstract
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.
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Affiliation(s)
- Michelle A Farrar
- Department of Neurology, Sydney Children's Hospital Network, Sydney, New South Wales, Australia.
- Discipline of Paediatrics and Child Health, UNSW Medicine and Health, School of Clinical Medicine, UNSW Sydney, Sydney, New South Wales, Australia.
| | - Loudella Calotes-Castillo
- Division of Paediatric Neurology, Department of Paediatrics and Neurosciences, University of the Philippines - Philippine General Hospital, Manila, Philippines
| | - Ranil De Silva
- Faculty of Medical Sciences, Interdisciplinary Centre for Innovation in Biotechnology and Neuroscience (ICIBN), University of Sri Jayewardenepura, Nugegoda, Sri Lanka
- Institute for Combinatorial Advanced Research and Education, General Sir John Kotelawala Defence University, Ratmalana, Sri Lanka
| | - Peter Barclay
- Pharmacy Department, Sydney Children's Hospitals Network, Sydney, New South Wales, Australia
| | - Lani Attwood
- Kids Advanced Therapeutics Programme, Sydney Children's Hospitals Network, Kids Research, Sydney, New South Wales, Australia
| | - Julie Cini
- Advocacy Beyond Borders, Melbourne, Australia
| | | | - Didu S Kariyawasam
- Department of Neurology, Sydney Children's Hospital Network, Sydney, New South Wales, Australia
- Discipline of Paediatrics and Child Health, UNSW Medicine and Health, School of Clinical Medicine, UNSW Sydney, Sydney, New South Wales, Australia
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Davidson JE, Russell JS, Martinez NN, Mowat DR, Jones KJ, Kirk EP, Kariyawasam D, Farrar M, D’Silva A. The Carrier Frequency of Two SMN1 Genes in Parents of Symptomatic Children with SMA and the Significance of SMN1 Exon 8 in Carriers. Genes (Basel) 2023; 14:1403. [PMID: 37510307 PMCID: PMC10379112 DOI: 10.3390/genes14071403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/03/2023] [Accepted: 07/03/2023] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND Current carrier screening methods do not identify a proportion of carriers that may have children affected by spinal muscular atrophy (SMA). Additional genetic data is essential to inform accurate risk assessment and genetic counselling of SMA carriers. This study aims to quantify the various genotypes among parents of children with SMA. METHOD A retrospective cohort study was undertaken at Sydney Children's Hospital Network, the major SMA referral centre for New South Wales, Australia. Participants included children with genetically confirmed SMA born between 2005 and 2021. Data was collected on parent genotype inclusive of copy number of SMN1 exons 7 and 8. The number of SMN2 exon 7 copies were recorded for the affected children. Descriptive statistics were used to determine the proportion of carriers of 2+0 genotype classified as silent carriers. Chi-square test was used to correlate the association between parents with a heterozygous SMN1 exon 7 deletion and two copies of exon 8 and ≥3 SMN2 copy number in the proband. RESULTS SMA carrier testing was performed in 118/154 (76.6%) parents, incorporating 59 probands with homozygous SMN1 deletions and one proband with compound heterozygote pathogenic variants. Among parents with a child with SMA, 7.6% had two copies of SMN1 exon 7. When only probands with a homozygous SMN1 exon 7 deletion were included, 6.9% of parents had two copies of SMN1 exon 7. An association was observed between heterozygous deletion of SMN1 exon 7 with two copies of exon 8 in a parent and ≥3 SMN2 copy number in the affected proband (p = 0.07). CONCLUSIONS This study confirmed a small but substantial proportion of silent carriers not identified by conventional screening within an Australian context. Accordingly, the effectiveness of carrier screening for SMA is linked with genetic counselling to enable health literacy regarding high and low risk results and is complemented by new-born screening and maintaining clinical awareness for SMA. Gene conversion events may underpin the associations between parent carrier status and proband SMN2 copy number.
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Affiliation(s)
- Joanne E Davidson
- Department of Neurology, Sydney Children’s Hospitals Network, Sydney, NSW 2031, Australia; (J.E.D.)
| | - Jacqueline S Russell
- Centre for Clinical Genetics, Sydney Children’s Hospital, Randwick, Sydney, NSW 2031, Australia; (J.S.R.)
| | - Noelia Nunez Martinez
- Centre for Clinical Genetics, Sydney Children’s Hospital, Randwick, Sydney, NSW 2031, Australia; (J.S.R.)
| | - David R Mowat
- Centre for Clinical Genetics, Sydney Children’s Hospital, Randwick, Sydney, NSW 2031, Australia; (J.S.R.)
| | - Kristi J Jones
- Department of Clinical Genetics, The Children’s Hospital at Westmead, and Discipline of Paediatrics and Child Health, University of Sydney, Sydney, NSW 2006, Australia
| | - Edwin P Kirk
- Centre for Clinical Genetics, Sydney Children’s Hospital, Randwick, Sydney, NSW 2031, Australia; (J.S.R.)
- Discipline of Paediatrics and Child Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, NSW 2052, Australia
| | - Didu Kariyawasam
- Department of Neurology, Sydney Children’s Hospitals Network, Sydney, NSW 2031, Australia; (J.E.D.)
- Discipline of Paediatrics and Child Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, NSW 2052, Australia
| | - Michelle Farrar
- Department of Neurology, Sydney Children’s Hospitals Network, Sydney, NSW 2031, Australia; (J.E.D.)
- Discipline of Paediatrics and Child Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, NSW 2052, Australia
| | - Arlene D’Silva
- Department of Neurology, Sydney Children’s Hospitals Network, Sydney, NSW 2031, Australia; (J.E.D.)
- Discipline of Paediatrics and Child Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, NSW 2052, Australia
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Balaji L, Farrar MA, D'Silva AM, Kariyawasam DS. Decision-making and challenges within the evolving treatment algorithm in spinal muscular atrophy: a clinical perspective. Expert Rev Neurother 2023; 23:571-586. [PMID: 37227306 DOI: 10.1080/14737175.2023.2218549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 05/23/2023] [Indexed: 05/26/2023]
Abstract
INTRODUCTION The clinical application of disease modifying therapies has dramatically changed the paradigm of the management of people with spinal muscular atrophy (SMA), from sole reliance on symptomatic care directed toward the downstream consequences of muscle weakness, to proactive intervention and even preventative care. AREAS COVERED In this perspective, the authors evaluate the contemporary therapeutic landscape of SMA and discuss the evolution of novel phenotypes and the treatment algorithm, including the key factors that define individual treatment choice and treatment response. The benefits achieved by early diagnosis and treatment through newborn screening are highlighted, alongside an appraisal of emerging prognostic methods and classification frameworks to inform clinicians, patients, and families about disease course, manage expectations, and improve care planning. A future perspective of unmet needs and challenges is provided, emphasizing the key role of research. EXPERT OPINION SMN-augmenting therapies have improved health outcomes for people with SMA and powered the practice of personalized medicine. Within this new proactive diagnostic and treatment paradigm, new phenotypes and different disease trajectories are emerging. Ongoing collaborative research efforts to understand the biology of SMA and define optimal response are critical to refining future approaches.
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Affiliation(s)
- Lakshmi Balaji
- Department of Neurology, Sydney Children's Hospital Network, Sydney, New South Wales, Australia
- Discipline of Paediatrics and Child Health, School of Clinical Medicine, UNSW Medicine and Health UNSW, Sydney, Australia
| | - Michelle A Farrar
- Department of Neurology, Sydney Children's Hospital Network, Sydney, New South Wales, Australia
- Discipline of Paediatrics and Child Health, School of Clinical Medicine, UNSW Medicine and Health UNSW, Sydney, Australia
- UNSW Kensington Campus, Sydney, Australia
| | - Arlene M D'Silva
- Department of Neurology, Sydney Children's Hospital Network, Sydney, New South Wales, Australia
- Discipline of Paediatrics and Child Health, School of Clinical Medicine, UNSW Medicine and Health UNSW, Sydney, Australia
- UNSW Kensington Campus, Sydney, Australia
| | - Didu S Kariyawasam
- Department of Neurology, Sydney Children's Hospital Network, Sydney, New South Wales, Australia
- Discipline of Paediatrics and Child Health, School of Clinical Medicine, UNSW Medicine and Health UNSW, Sydney, Australia
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Green AG. Spinal muscular atrophy and the world's most expensive medicines: The price of life. Dev Med Child Neurol 2022; 64:676-677. [PMID: 35304751 DOI: 10.1111/dmcn.15204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 11/30/2022]
Affiliation(s)
- Arthur G Green
- Department of Geography, Earth, and Environmental Sciences, Okanagan College, Kelowna, British Columbia, Canada
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Markati T, Fisher G, Ramdas S, Servais L. Risdiplam: an investigational motor neuron-2 (SMN-2) splicing modifier for spinal muscular atrophy (SMA). Expert Opin Investig Drugs 2022; 31:451-461. [PMID: 35316106 DOI: 10.1080/13543784.2022.2056836] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Spinal muscular atrophy (SMA) is a rare autosomal recessive neuromuscular disease which is characterized by muscle atrophy and early death in most patients. Risdiplam is the third overall and first oral drug approved for SMA with disease-modifying potential. Risdiplam acts as a survival motor neuron 2 (SMN2) pre-mRNA splicing modifier with satisfactory safety and efficacy profile. This review aims to critically appraise the place of risdiplam in the map of SMA therapeutics. AREAS COVERED This review gives an overview of the current market for SMA and presents the mechanism of action and the pharmacological properties of risdiplam. It also outlines the development of risdiplam from early preclinical stages through to the most recently published results from phase 2/3 clinical trials. Risdiplam has proved its efficacy in pivotal trials for SMA Types 1, 2, and 3 with a satisfactory safety profile. EXPERT OPINION In the absence of comparative data with the other two approved drugs, the role of risdiplam in the treatment algorithm of affected individuals is examined in three different patient populations based on the age and diagnosis method (newborn screening or clinical, symptom-driven diagnosis). Long-term data and real-world data will play a fundamental role in its future.
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Affiliation(s)
- Theodora Markati
- MDUK Oxford Neuromuscular Center, Department of Paediatrics, University of Oxford, Oxford, UK.,Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Gemma Fisher
- MDUK Oxford Neuromuscular Center, Department of Paediatrics, University of Oxford, Oxford, UK.,Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Sithara Ramdas
- MDUK Oxford Neuromuscular Center, Department of Paediatrics, University of Oxford, Oxford, UK.,Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Laurent Servais
- MDUK Oxford Neuromuscular Center, Department of Paediatrics, University of Oxford, Oxford, UK.,Oxford University Hospitals NHS Foundation Trust, Oxford, UK.,Division of Child Neurology, Centre de Références des Maladies Neuromusculaires, Department of Pediatrics, University Hospital Liège & University of Liège, Belgium
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