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Muscular Dystrophy Association Announces Nearly $400K in Research Grants to Address Challenges in Duchenne Muscular Dystrophy Gene Therapy

New York, NY – March 13, 2023, Today, Muscular Dystrophy Association (MDA) announced two research grants designed to address potential transgene-triggered safety concerns in Duchenne muscular dystrophy (DMD) gene therapies. Jeffrey Chamberlain, Ph.D., Neurology, Biochemistry, Medicine/Medical Genetics, McCaw Chair in Muscular Dystrophy and Professor at the Institute for Stem Cell & Regenerative Medicine at the University of Washington, receives a $200,000 grant for a two-year study on expression of enhanced dystrophins via Adeno-associated viruses (AAV) to circumvent immune responses linked to a subpopulation of DMD patients. Carrie Miceli, Ph.D., Professor of Microbiology, Immunology and Molecular Genetics, Co-Director, Center for Duchenne Muscular Dystrophy, UCLA School of Medicine, receives $199,962 for a two-year study of single cell transcriptomics to assess transgene related molecular responses in DMD. These awards arise as a result of the MDA Gene Therapy Summit in 2022 in which global leaders from the field of gene therapy convened to discuss safety issues and challenges in the clinical translation of AAV-based gene therapies. A meeting report summarizing the presentations is available pre-press in the Journal of Neuromuscular Diseases here.

DMD is an X-linked disorder caused by mutations in the dystrophin gene that results in muscle wasting and weakness. Gene replacement strategies using AAV technology have proven to be a very promising approach for restoring dystrophin protein function and are currently being pursued by several companies. However, recent collaborative efforts between DMD gene therapy trial sponsors revealed a class of safety issues arising from AAV microdystrophin gene therapy.

"With these grants, we continue our longstanding collaboration with industry and academic partners to identify bottlenecks and ways to safely translate gene therapies for neuromuscular disorders. Since our inception, Muscular Dystrophy Association has invested almost $227 million in Duchenne muscular dystrophy and Becker muscular dystrophy research, and over $125 million in the development of gene therapies for neuromuscular disorders. These studies by Dr. Chamberlain and Dr. Miceli help to enhance understanding and mitigate immune response safety issues associated with DMD gene therapies. These studies may provide important lessons that will translate across gene therapies for other neuromuscular disorders," said Sharon Hesterlee, Ph.D., Chief Research Officer, MDA.

“We are deeply appreciative of the ongoing support the Muscular Dystrophy Association has provided our lab over the years. Grants from MDA have helped us to understand the function of dystrophin, followed by the design of dystrophin gene replacement therapies, and their testing in animal models. This most recent funding will help us design the next generation of dystrophin gene replacement therapies that avoid transgene-triggered immune responses, allowing more Duchenne muscular dystrophy patients to be candidates for treatment," said Dr. Chamberlain.

"We are grateful to the Muscular Dystrophy Association for this funding, which lets us track the effects of micro-dystrophin gene therapy at single cell resolution by sequencing individual nuclei isolated from post-treatment muscle biopsies. Our studies promise to teach us about immune response to gene therapy, durability of micro-dystrophin expression and identify druggable pathways for improving safety and efficacy of gene therapies," said Dr. Miceli.

MDA's history and future with Duchenne muscular dystrophy:

• Muscular Dystrophy Association has been at the forefront of advancements in Duchenne muscular dystrophy since the inception of the organization 73 years ago.
• Together with families across the country, the organization's innovative philanthropy fueled the entire creation of the field of neuromuscular disease research, care and treatments, resources, and advocacy.
• In the 1980s MDA's Genetic Task Force led the way to the discovery of the gene that causes DMD, paving the way for the breakthroughs we see today in genetic medicine.
• MDA's Care Center Network of multidisciplinary medical teams in over 150 of the nation's top medial institutions continues to lead the way in accelerating research and advancing care and delivering on the hope for families that is the bedrock of the mission. This is the first ever network with the infrastructure to educate medical professionals and specialists to deliver gene therapy to patients based on models from MDA supported breakthroughs in spinal muscular atrophy with treatments such as Spinraza and Zolgensma. Innovations continue in the MDA Care Center Network to deliver the next breakthrough treatments in gene therapy to patients with DMD.
• MDA's advocacy program supports policies that advance biomedical research, ensure that safe and effective treatments are developed and delivered as quickly as possible, improve access to care and services, and maximize opportunities for independence. In June 2022, MDA co-sponsored the nomination of DMD for the Recommended Uniform Screening Panel (RUSP). Recently, the Secretary's Advisory Committee on Heritable Disorders in Newborns and Children (ACHNDC or “the Committee") voted against moving the nomination of DMD forward. Consequently, additional supporting evidence must be submitted to the Committee prior to the nomination advancing further. MDA urged the Committee to move the nomination to the next stage and the organization is undeterred in efforts to add Duchenne to the RUSP. Read this statement on MDA’s continued work.

Award to Jeffrey Chamberlain, Ph.D., University of Washington:

Gene therapy for DMD is aimed at treating the cause of the disorder: a lack of dystrophin. Currently, the only known method for dystrophin delivery to muscles bodywide is by infusion of adeno-associated viral (AAV) vectors carrying miniaturized dystrophin genes. These AAV-microdystrophin (µDys) vectors have shown dramatic effects in animal models and are being tested in clinical trials. However, the observation of serious adverse events (SAEs) in 5 patients who were missing (deleted for) a part of the gene that is carried by µDys vectors has shown that parts of dystrophin can lead to a serious immune response in some patients. The immediate consequence of this has been that such patients (10-15% of all DMD boys) are being excluded from gene therapy trials. Our group has been studying dystrophin immunity for many years due to concerns that such a situation might emerge, and we have developed a computational method to predict immunogenic regions of dystrophin and to redesign vectors to remove problematic parts of the protein. To date we have successfully redesigned several portions of micro/mini-dystrophin and shown that they can be functional, stable and non-immunogenic in animal models. Here we propose to extend these studies to the problematic region recently identified in the clinic. Our goal is to develop modified dystrophin clones that could be used in clinical trials and thus allow broad enrollment of patients regardless of their underlying genetic mutation.

Award to Carrie Miceli, Ph.D., University of California Los Angeles:

Duchenne muscular dystrophy is the most common and ultimately lethal genetic muscle disease of humans, without adequate therapeutic options. Recent advances in gene therapy using AAV vectors to transfer micro-dystrophin with durable expression are promising, but adverse events may limit safety and effectiveness because of immunologic barriers that are incompletely understood. New methods for identification of single cell and single nuclei gene expression reveal the complex tissue landscape in DMD and enable elucidation of changes in response to micro-dystrophin expression. Here we propose to apply this methodology to evaluate muscle biopsies from post gene therapy patients to assess durability of myofiber transgene expression alongside intra-muscular immune responses controlling micro-dystrophin immune tolerance and activation, and muscle health. Our finding may reveal how to reduce serious immediate and long-term adverse events, strategies for mitigation, and allow the broadening of eligibility of inclusion in clinical trials for micro-dystrophin gene therapy.

2023 MDA Clinical & Scientific Conference:

On March 19-22, 2023, the world's largest convening of neuromuscular disease professionals takes place in Dallas, Texas for the MDA Clinical and Scientific Conference with more breaking news in the field of DMD to be presented. The Conference will include over 1,600 attendees, 45 exhibitors, 14 patient advocacy organizations, over 250 abstracts. View the full agenda here.

MDA's Care Center Network is nationwide in over 150 locations, and specifically in Texas at: Baylor College of Medicine, Central Texas Neurology Consultants, Child Neurology Consultants of Austin, Children's Hospital of San Antonio, Children's Medical Center of Dallas, Cook Children's Medical Center, Dell Children's Medical Center, Driscoll Children's Hospital, Houston Methodist Neurological Institute, Methodist Neurology Associates, Texas Children's Hospital, Texas Neurology P.A., University of Texas Health Sciences Center, University of Texas Southwestern.

About Muscular Dystrophy Association

Muscular Dystrophy Association (MDA) is the #1 voluntary health organization in the United States for people living with muscular dystrophy, ALS, and related neuromuscular diseases. For over 70 years, MDA has led the way in accelerating research, advancing care, and advocating for the support of our families. MDA's mission is to empower the people we serve to live longer, more independent lives. To learn more visit mda.org and follow MDA on Instagram, Facebook, Twitter, TikTok, LinkedIn, and YouTube.