Experts Assess Promise of Vamorolone to Treat Duchenne Muscular Dystrophy
Commentary in the Journal of Neuromuscular Diseases provides an independent, unbiased assessment of the body of research on vamorolone
Authors Miranda D. Grounds, PhD, and Erin M. Lloyd, PhD, both of the Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, conclude that vamorolone (also known as VBP15) is a promising steroid treatment for DMD, with similar efficacy and evidence for some reduced adverse side effects compared with traditional glucocorticoid steroid treatments, such as prednisone. However, certain issues require clarification and further investigation.
Drawing on more than 40 years of research in skeletal muscle cell biology with a view towards clinical translation to treat neuromuscular disorders including DMD, Professor Grounds explains, "An independent assessment of the research around vamorolone for DMD treatment is of importance for the wide DMD community, which includes young patients with DMD and their families, associated clinicians, scientists, researchers, and other experts around the world. There is an urgent need for therapies and superior drugs to treat this lethal childhood disease. Vamorolone is also of potential interest for other muscular dystrophies."
DMD is an inherited X chromosome-linked muscle disorder, manifesting in young children and predominantly affecting males, resulting in rapid loss of muscle mass and of function of most skeletal muscles. Symptoms are evident around 2–3 years of age, and many boys become wheelchair dependent around 10–12 years old. Further complications include progressive degeneration of muscles, scoliosis, contractures, and increasing respiratory and cardiac complications with age. However, with modern interventions and care, the lifespan of patients with DMD can be extended to about 20–40 years. In addition, new gene therapies are in development.
Glucocorticoids such as prednisone and deflazacort, that have broad targets, including the inflammatory system, are considered the standard of care for DMD because they slow down disease progression, but long-term use can result in severe adverse side effects. Vamorolone was designed as a unique dissociative steroidal anti-inflammatory drug to retain efficacy and minimize these adverse effects.
The analysis for this Commentary entailed a thorough evaluation of documented results from clinical and pre-clinical studies of vamorolone, as well as an in-depth assessment of completed and ongoing clinical trials. The authors found that vamorolone has similar efficacy to prednisone in terms of improved muscle function and reduced inflammation, with some reduced adverse side effects related to growth and bone quality (compared to those from prednisone and deflazacort), but adverse effects such as adrenal suppression were still evident and influenced by dose.
"In the clinical trial results, we noted that there have been surprisingly few direct comparisons of vamorolone treatment with prednisone and deflazacort, since many of the early clinical trials mainly compared the effects of vamorolone with data for age-matched untreated (or placebo) DMD boys,” says Dr. Lloyd. “Only one completed trial compared a relatively short-term (6-month) vamorolone treatment with prednisone treatment. To date, vamorolone has not been directly compared with deflazacort."
Based on their in-depth analysis of pre-clinical trial results, the authors identified issues that would benefit from further clarification:
- Does vamorolone protect (or reduce) dystrophic muscles from necrosis? Muscle necrosis is the central problem in the breakdown of skeletal muscles in DMD, and vamorolone’s direct impact on necrosis is not clearly demonstrated in the current body of research.
- The observation that vamorolone improves membrane repair following experimental injury piques interest. However, it is hard to extrapolate these observations to the realistic in vivo situation of intrinsic muscle damage in DMD (and other muscular dystrophies such as dysferlinopathy). Further studies to interrogate the precise in vivo mechanisms behind these observations are welcomed for DMD and other muscular dystrophies.
The authors note that most of the clinical and pre-clinical studies have been conducted by large international networks of collaborators, and advise that "For future pre-clinical studies, it is desirable for some independent researchers to conduct investigations to validate the main findings of the existing body of work and provide further insights into the mechanisms of action of vamorolone."
Professor Grounds and Dr. Lloyd add, "An important consideration is the likely cost of vamorolone for clinical use, compared with existing drugs. While it is recognized that drug development is a very expensive process, extraordinarily high prices for consumers present difficulties for patient access to treatments and for global health systems. This issue and others require balanced critical discussion by the wider community."
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NOTES FOR EDITORS
“Considering the Promise of Vamorolone for Treating Duchenne Muscular Dystrophy,” by Miranda D. Grounds, PhD, and Erin M. Lloyd, PhD (https://doi.org/10.3233/JND-230161), Journal of Neuromuscular Diseases, Volume 10, issue 6. The article is openly available at https://content.iospress.com/articles/journal-of-neuromuscular-diseases…;
Full text of this paper is also available to credentialed journalists upon request. Please contact Diana Murray, IOS Press, at +1 718-640-5678 or email@example.com for the full text of the article or additional information. Journalists who wish to interview the authors should contact Simone Hewett, UWA Media & PR Manager at +61 8 6488 3229 / +61 432 637 716 or firstname.lastname@example.org.
The authors have no conflicts of interest to report.
ABOUT THE JOURNAL OF NEUROMUSCULAR DISEASES (JND)
The Journal of Neuromuscular Diseases facilitates progress in understanding the molecular genetics/correlates, pathogenesis, pharmacology, diagnosis, and treatment of acquired and genetic neuromuscular diseases (including muscular dystrophy, myasthenia gravis, spinal muscular atrophy, neuropathies, myopathies, myotonias, and myositis). The journal publishes research reports, reviews, and short communications. Guided by Editors-in-Chief Carsten G. Bönnemann (National Institute of Neurological Disorders and Stroke, NIH) and Hanns Lochmüller (Children’s Hospital of Eastern Ontario Research Institute), the journal is dedicated to providing an open forum for original research in basic science, translational, and clinical research that will improve our fundamental understanding and lead to effective treatments of neuromuscular diseases. www.iospress.com/journal-of-neuromuscular-diseases
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