A surprising discovery offers a potential new avenue of hope for children and young adults battling Leigh syndrome, a devastating and currently untreatable metabolic disorder. Researchers have found that sildenafil – the active ingredient in Viagra – demonstrated positive effects in a small pilot study, improving muscle strength and reducing the frequency of debilitating metabolic crises. The findings, published in the journal Cell, represent a significant step forward in the search for therapies for this rare condition.
Leigh syndrome, affecting approximately one in 36,000 children, disrupts energy metabolism, leading to progressive neurological and muscular deterioration. Symptoms typically emerge in infancy or early childhood and include seizures, muscle weakness, and developmental delays. Currently, Notice no approved drug therapies to leisurely or halt the progression of this life-limiting illness, making this research particularly noteworthy.
The study, conducted by researchers at Charité – Universitätsmedizin Berlin, in collaboration with teams from Heinrich Heine University Düsseldorf (HHU), University Hospital Düsseldorf (UKD), and the Fraunhofer Institute for Translational Medicine and Pharmacology ITMP in Hamburg, involved six patients aged between 9 months and 38 years. Participants received continuous sildenafil treatment, and within months, researchers observed improvements in muscular strength and, in some cases, a reduction in neurological symptoms. Notably, the frequency of metabolic crises – sudden and dangerous overloads of the energy metabolism – also decreased.
“For example, in the case of a child undergoing sildenafil treatment, the walking distance increased tenfold, from 500 to 5,000 meters,” explained Professor Markus Schuelke, a physician and scientist at Charité’s Department of Pediatric Neurology and one of the lead authors of the study. “In another child, the therapy completely suppressed metabolic crises that occurred almost monthly, while another patient no longer suffered from epileptic seizures.”
Identifying a Potential Treatment Through Innovative Research
The path to this discovery wasn’t straightforward. Researchers employed a novel approach, utilizing induced pluripotent stem cells – cells capable of developing into various cell types – derived from the patients’ skin cells. These stem cells were then used to culture nerve cells exhibiting the same metabolic defects as those found in individuals with Leigh syndrome. The team then screened over 5,500 existing drugs for their potential to improve the function of these defective nerve cells. This screening process identified sildenafil as a promising candidate.
“What we have is the largest drug screening for the treatment of Leigh syndrome to date,” stated Dr. Ole Pless, lead author of the study from ITMP. “It showed that sildenafil, among other drugs, improved the electrical functionality of the nerve cells.” Further laboratory tests, including studies using three-dimensional brain organoids, confirmed these initial findings, demonstrating that sildenafil enhanced nerve cell growth and improved energy metabolism in animal models.
Safety and Orphan Drug Designation
Given the promising preclinical results and the existing safety data for sildenafil – already approved for treating pulmonary hypertension in infants and erectile dysfunction in adults – the research team initiated an individual therapeutic trial in the six patients. All patients tolerated the drug well, according to the study. The European Medicines Agency (EMA) has since granted sildenafil orphan drug status, a designation for medications treating rare diseases, which can expedite the approval process.
The researchers are now planning a larger, Europe-wide, placebo-controlled clinical trial as part of the SIMPATHIC EU project to validate these initial findings and pave the way for potential approval of sildenafil as a treatment for Leigh syndrome. This trial will be crucial in determining the drug’s long-term efficacy and safety.
While the findings are encouraging, Professor Schuelke emphasized the need for further research. “Such effects significantly improve the quality of life of Leigh syndrome patients. While we will have to confirm these initial observations in a more comprehensive study, we are very pleased to have found a promising drug candidate for the treatment of this serious hereditary disease.”
Disclaimer: This article provides information for general knowledge and informational purposes only, and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
The potential repurposing of sildenafil for Leigh syndrome highlights the importance of continued research into rare diseases and the innovative approaches needed to develop effective treatments. The upcoming clinical trial will be a critical step in determining whether this unexpected finding can translate into a life-changing therapy for those affected by this devastating condition.
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