Breakthrough to Bedside: Bringing Gene Therapy to Neuromuscular Diseases.

In this article, the authors discuss how they utilized the genetic mutation data in Sri Lankan Duchenne muscular dystrophy (DMD), Spinal muscular atrophy (SMA), Spinocerebellar ataxia (SCA) and Huntington's disease (HD) patients and compare the available literature from South Asian countries to identifying potential candidates for available gene therapy for DMD, SMA, SCA and HD patients. Rare disease patients (n=623) with the characteristic clinical findings suspected of HD, SCA, SMA and Muscular Dystrophy were genetically confirmed using Multiplex Ligation Dependent Probe Amplification (MLPA), and single plex PCR. A survey was conducted in the "Wiley database on Gene Therapy Trials Worldwide" to identify DMD, SMA, SCA, and HD gene therapy clinical trials performed worldwide up to April 2021. In order to identify candidates for gene therapy in other neighboring countries we compared our findings with available literature from India and Pakistan which has utilized the same molecular diagnostic protocol to our study. From the overall cohort of 623 rare disease patients with the characteristic clinical findings suspected of HD, SCA, SMA and Muscular Dystrophy, n=343 (55%) [Muscular Dystrophy- 65%; (DMD-139, Becker Muscular Dystrophy -BMD-11), SCA type 1-3-53% (SCA1-61,SCA2- 23, SCA3- 39), HD- 52% (45) and SMA- 34% (22)] patients were positive for molecular diagnostics by MLPA and single plex PCR. A total of 147 patients in Sri Lanka amenable to available gene therapy; [DMD-83, SMA-15 and HD-49] were identified. A comparison of Sri Lankan finding with available literature from India and Pakistan identified a total of 1257 patients [DMD-1076, SMA- 57, and HD-124] from these three South Asian Countries as amenable for existing gene therapy trials. DMD, SMA, and HD gene therapy clinical trials (113 studies) performed worldwide up to April 2021 were concentrated mostly (99%) in High Income Countries (HIC) and Upper Middle-Income Countries (UMIC). However, studies on the potential use of anti-sense oligonucleotides (ASO) for treatment of SCAs have yet to reach clinical trials. Most genetic therapies for neurodegenerative and neuromuscular disorders have been evaluated for efficacy primarily in Western populations. No multicenter gene therapy clinical trial sites for DMD, SMA and HD in the South Asian region, leading to lack of knowledge on the safety and efficacy of such personalized therapies in other populations, including South Asians. By fostering collaboration between researchers, clinicians, patient advocacy groups, government and industry in gene therapy initiatives for the inherited-diseases community in the developing world would link the Global North and Global South and breathe life into the motto "Together we can make a difference".

AimsBackgroundInfants with Spinal muscular atrophy type 1 (SMA-1) may have reduced cough mechanism, impaired airway clearance and consequent risk of severe respiratory illness. Major advances in the last decade include...

Cooperation is key, say neuromuscular-disease researchers

Neurodegenerative disorders (NDDs), such as Alzheimer's disease (AD) and Parkinson's Disease (PD), are a group of heterogeneous diseases that mainly affect central nervous system (CNS) functions. A subset of NDDs exhibit CNS dysfunction and muscle degeneration, as observed in Gangliosidosis 1 (GM1) and late stages of PD. Neuromuscular disorders (NMDs) are a group of diseases in which patients show primary progressive muscle weaknesses, including Duchenne Muscular Dystrophy (DMD), Pompe disease, and Spinal Muscular Atrophy (SMA). NDDs and NMDs typically have a genetic component, which affects the physiological functioning of critical cellular processes, leading to pathogenesis. Currently, there is no cure or efficient treatment for most of these diseases. More than 200 clinical trials have been completed or are currently underway in order to establish safety, tolerability, and efficacy of promising gene therapy approaches. Thus, gene therapy-based therapeutics, including viral or non-viral delivery, are very appealing for the treatment of NDDs and NMDs. In particular, adeno-associated viral vectors (AAV) are an attractive option for gene therapy for NDDs and NMDs. However, limitations have been identified after systemic delivery, including the suboptimal capacity of these therapies to traverse the blood-brain barrier (BBB), degradation of the particles during the delivery, high reactivity of the patient's immune system during the treatment, and the potential need for redosing. To circumvent these limitations, several preclinical and clinical studies have suggested intrathecal (IT) delivery to target the CNS and peripheral organs via cerebrospinal fluid (CSF). CSF administration can vastly improve the delivery of small molecules and drugs to the brain and spinal cord as compared to systemic delivery. Here, we review AAV biology and vector design elements, different therapeutic routes of administration, and highlight CSF delivery as an attractive route of administration. We discuss the different aspects of neuromuscular and neurodegenerative diseases, such as pathogenesis, the landscape of mutations, and the biological processes associated with the disease. We also describe the hallmarks of NDDs and NMDs as well as discuss current therapeutic approaches and clinical progress in viral and non-viral gene therapy and enzyme replacement strategies for those diseases.

The field of gene therapy is growing at a rapid pace. The discovery and modification of adeno-associated viruses (AAV) as gene therapy vectors has allowed for the development of novel treatments for neurological and neuromuscular disorders. AAV based gene therapy techniques can be utilized to add, replace, or modify genes and their expression in patients, thus providing a potential beneficial therapeutic effect. In many cases, gene therapy has the promising power to change the natural course of debilitating and fatal diseases and give patients a new outcome on life. This mini review will give a brief overview of the AAV gene therapy field, highlighting FDA approved gene therapies and selected current in-clinic AAV-mediated therapeutics for neurological and neuromuscular diseases for which interim data are available. These therapies and the ongoing clinical trials are currently laying the groundwork for future gene therapy strategies and clinical trial design. Ultimately, they will inform the field on promises and limitations that still need to be overcome.

Gene therapy in the treatment of disease

Pompe disease is a neuromuscular disorder caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA), hydrolyzing glycogen to glucose. Pathological glycogen storage, the hallmark of the disease, disrupts the metabolism and function of various cell types, especially muscle cells, leading to cardiac, motor, and respiratory dysfunctions. The spectrum of Pompe disease manifestations spans two main forms: classical infantile-onset (IOPD) and late-onset (LOPD). IOPD, caused by almost complete GAA deficiency, presents at birth and leads to premature death by the age of 2 years without treatment. LOPD, less severe due to partial GAA activity, appears in childhood, adolescence, or adulthood with muscle weakness and respiratory problems. Since 2006, enzyme replacement therapy (ERT) has been approved for Pompe disease, offering clinical benefits but not a cure. However, advances in early diagnosis through newborn screening, recognizing disease manifestations, and developing improved treatments are set to enhance Pompe disease care. This article reviews recent progress in ERT and ongoing translational research, including the approval of second-generation ERTs, a clinical trial of in utero ERT, and preclinical development of gene and substrate reduction therapies. Notably, gene therapy using intravenous delivery of adeno-associated virus (AAV) vectors is in phase I/II clinical trials for both LOPD and IOPD. Promising data from LOPD trials indicate that most participants met the criteria to discontinue ERT several months after gene therapy. The advantages and challenges of this approach are discussed. Overall, significant progress is being made towards curative therapies for Pompe disease. While several challenges remain, emerging data are promising and suggest the potential for a once-in-a-lifetime treatment.

Neuromuscular diseases (NMDs) are a group of rare disorders characterized by significant genetic and clinical complexity. Advances in genomics have revolutionized both the diagnosis and treatment of NMDs. While fewer than 30 NMDs had known genetic causes before the 1990s, more than 600 have now been identified, largely due to the adoption of next-generation sequencing (NGS) technologies such as whole-exome sequencing (WES) and whole-genome sequencing (WGS). These technologies have enabled more precise and earlier diagnoses, although the genetic complexity of many NMDs continues to pose challenges. Gene therapy has been a transformative breakthrough in the treatment of NMDs. In spinal muscular atrophy (SMA), therapies like nusinersen, onasemnogene abeparvovec, and risdiplam have dramatically improved patient outcomes. Similarly, Duchenne muscular dystrophy (DMD) has seen significant progress, most notably with the FDA approval of delandistrogene moxeparvovec, the first micro-dystrophin gene therapy. Despite these advancements, challenges remain, including the rarity of many NMDs, genetic heterogeneity, and the high costs associated with genomic technologies and therapies. Continued progress in gene therapy, RNA-based therapeutics, and personalized medicine holds promise for further breakthroughs in the management of these debilitating diseases.

Neuromuscular diseases are multifactorial pathologies characterized by extensive muscle fiber damage that leads to the activation of satellite cells and to the exhaustion of their pool, with consequent impairment of neurobiological aspects, such as cognition and motor control. To review the knowledge and obtain a broad view of the cognitive impairment on Neuromuscular Diseases. Cognitive impairment in neuromuscular disease was explored; a literature search up to October 2017 was conducted, including experimental studies, case reports and reviews written in English. Keywords included Cognitive Impairment, Neuromuscular Diseases, Motor Neuron Diseases, Dystrophinopathies and Mitochondrial Disorders. Several cognitive evaluation scales, neuroimaging scans, genetic analysis and laboratory applications in neuromuscular diseases, especially when it comes to the Motor Neuron Diseases, Dystrophinopathies and Mitochondrial Disorders. In addition, organisms model using rats in the genetic analysis and laboratory applications to verify the cognitive and neuromuscular impacts. Several studies indicate that congenital molecular alterations in neuromuscular diseases promote cognitive dysfunctions. Understanding these mechanisms may in the future guide the proper management of the patient, evaluation, establishment of prognosis, choice of treatment and development of innovative interventions such as gene therapy.

British Society for Gene and Cell Therapy Annual Conference Glasgow9–11th June 2015Conference Abstracts

Rapid progress in genetic research and the subsequent emergence of diverse gene therapy for hereditary neuromuscular diseases lead to the need to create specialized clinics or beds in neurological hospitals. The physicians in this area of medical practice are required to have deep knowledge of this extremely extensive group of diseases (more than 1,100 diseases) and, accordingly, a narrow specialization in the field of myology. An additional problem is the polysystemic nature of the neuromuscular diseases and the need for diagnostics and management by a team of different specialists (neurologists, geneticists, cardiologists, orthopedists, palliative medicine specialists, etc.), which is only possible in a multidisciplinary clinic. An outstanding achievement is the provision of gene therapy to all children with spinal muscular atrophy and a significant portion of patients with Duchenne muscular dystrophy in the Russian Federation, thanks to the “Circle of Goodness” charity foundation and the introduction of neonatal screening for spinal muscular atrophy. At the same time, this poses new challenges for doctors that need to be addressed. The article describes the problems of choosing drugs for gene therapy, assessing their effectiveness, the high expectations among parents of symptomatic patients with neuromuscular diseases receiving gene therapy, the need to create national registries that include an assessment of the effectiveness of therapy. A separate scientific problem is the change in the phenotype of spinal muscular atrophy and Duchenne muscular dystrophy on gene therapy, which requires long-term study and may lead to a change in the standards of patient management.

Duchenne muscular dystrophy (DMD) is a progressive, life-limiting, neuromuscular disorder. Clinicians play an important role in informing families about therapy options, including approved gene therapies and clinical trials of unapproved therapies. This study aimed to understand the perspectives of clinicians about gene therapy for DMD, which has not previously been studied. We conducted interviews with specialist clinicians treating patients with DMD in the United States (n = 8) and United Kingdom (n = 8). Interviews were completed in 2022, before any approved gene therapies, to gain insight into barriers and facilitators to implementing gene therapy and educational needs of clinicians. Most respondents expressed cautious optimism about gene therapy. Responses varied regarding potential benefits with most expecting delayed progression and duration of benefit (1 year to lifelong). Concern about anticipated risks also varied; types of anticipated risks included immunological reactions, liver toxicity, and cardiac or renal dysfunction. Clinicians generally, but not uniformly, understood that gene therapy for DMD would not be curative. Most reported needing demonstrable clinical benefit to justify treatment-related risks. Our data demonstrate variability in knowledge and attitudes about gene therapy among clinicians who follow patients with DMD. As our knowledge base about DMD gene therapy grows, clinician education is vital to ensuring that accurate information is communicated to patients and families.

ABSTRACTIntroduction: The well-defined genetic causes and monogenetic nature of many neuromuscular disorders, including Duchenne muscular dystrophy (DMD) and spinal muscular atrophy (SMA), present gene therapy as a prominent therapeutic approach. The novel variants of adeno-associated virus (AAV) can achieve satisfactory transduction efficiency of exogenous genes through the central nervous system and body-wide in skeletal muscle.Areas covered: In this review, we summarize the strategies of AAV gene therapy that are currently under preclinical and clinical evaluation for the treatment of degenerative neuromuscular disorders, with a focus on diseases such as DMD and SMA. In addition to gene replacement strategy, we provide an overview of other approaches such as AAV-mediated RNA therapy and gene editing in the treatment of muscular dystrophies.Expert opinion: AAV gene therapy has achieved striking therapeutic efficacy in clinical trials in infants with SMA. Promising results have also come from the preclinical studies in small and large animal models of DMD and several clinical trials are now on the way. This strategy shows great potential as a therapy for various neuromuscular disorders. Further studies are still required to confirm its long-term safety and improve the efficacy.

For many neuromuscular disorders, including Duchenne muscular dystrophy, spinal muscular atrophy and myotonic dystrophy, the genetic causes are well known. Gene therapy holds promise for the treatment of these monogenic neuromuscular diseases, and many such therapies have made substantial strides toward clinical translation. Recently, genome engineering tools, including targeted gene editing and gene regulation, have become available to correct the underlying genetic mutations that cause these diseases. In particular, meganucleases, zinc finger nucleases, TALENs, and the CRISPR-Cas9 system have been harnessed to make targeted and specific modifications to the genome. However, for most gene therapy applications, including genome engineering, gene delivery remains the primary hurdle to clinical translation. In preclinical models, genome engineering tools have been delivered via gene-modified cells or by non-viral or viral vectors to correct a diverse array of genetic diseases. In light of the positive results of these studies, genome engineering therapies are being enthusiastically explored for several genetic neuromuscular disorders. This Review summarizes the genome engineering strategies that are currently under preclinical evaluation for the treatment of degenerative neuromuscular disorders, with a focus on the molecular tools that show the greatest potential for clinical translation of these therapies.

A growing number of gene therapies are getting FDA-approved for pediatric rare disorders to treat once incurable diseases. Opportunities for preventing lifetime illness and improving quality of life for these patients is now becoming a reality. Challenges exist in navigating the complexities of determining which patients will benefit from these new gene therapies and how to effectively deliver them as a standard of care. Gene therapies have been approved for pediatric hematological, neuromuscular, cancer, and other disorders that have improved the quality of life for rare disease patients. FDA approval of these drugs has been on a case-by-case basis leading towards gaps in drug approval, physician and patient knowledge of new gene therapies, and ultimate delivery of these drugs. Identifying patients that would benefit from these drugs and other coordination of care issues have arisen with each unique gene therapy product. These gene therapies have unique requirements and patient indications that require a knowledgeable group of physicians and hospital administrators to incorporate their use as a standard of care. With more gene therapies on the near horizon for FDA approval, multidisciplinary teams may improve patient access to these drugs by streamlining approaches towards adapting gene therapies into clinical use. The rapid increase in the number of FDA-approved gene therapies has not only created a number of challenges but also opportunities to improve the lives of pediatric patients with rare disorders. The adaptability of physicians, hospitals, and governmental regulatory boards is essential for delivering these new gene therapies safely and efficiently to these rare disease patients. Challenges still remain as to future requirements for additional gene therapy dosing and how to best manage financial burdens placed on the patient and providing institution.