In a significant setback for Parkinson's disease research, a major clinical trial has found that exenatide, a drug in the same GLP-1 class as Wegovy and Ozempic, failed to demonstrate any benefit in treating or slowing the progression of Parkinson's disease.
The comprehensive Phase 3 trial, conducted across six research hospitals in the United Kingdom, involved 194 participants with Parkinson's disease who received either weekly exenatide injections or a visually identical placebo over 96 weeks. The study, published in The Lancet, employed a rigorous double-blind methodology, with neither researchers nor participants aware of their treatment assignment.
Trial Design and Results
The research team, led by Professor Thomas Foltynie of UCL Queen Square Institute of Neurology, found no advantages in the exenatide group throughout the entire study period. "It's hugely disappointing," said Dr. Foltynie. "We were expecting we would come through and we would get a positive result."
The study evaluated multiple outcomes, including:
- Objective examination of patient movements
- Patient-reported symptom severity
- Brain imaging findings
None of these measures showed any improvement or disease-slowing effects in the treatment group compared to placebo.
Clinical Impact and Current Treatment Landscape
The results are particularly disappointing given the current treatment limitations for Parkinson's disease, which affects approximately half a million Americans. While existing treatments, including medications and deep brain stimulation, can help manage symptoms such as tremors, stiffness, and balance difficulties, no available therapy has demonstrated the ability to slow disease progression.
"This is a sobering moment," commented Dr. Michael S. Okun, Parkinson's disease expert at the University of Florida and national medical adviser for the Parkinson's Foundation. "This is a really well done study and it came up empty-handed."
Scientific Context and Future Directions
The trial's negative outcome is particularly notable given the recent success of GLP-1 drugs in treating conditions like Type 2 diabetes and obesity. Earlier small-scale studies had suggested potential benefits of exenatide for Parkinson's patients, leading to optimism in the research community.
Professor Foltynie noted that further analysis of the data might reveal whether specific subgroups of patients, such as those with pre-diabetes, might respond differently to the treatment. The study's high participant retention rate and confirmed medication compliance through blood testing lend additional credibility to these findings.
The research was supported by several prestigious institutions, including the National Institute for Health & Care Research (NIHR), Cure Parkinson's, Van Andel Institute, and the UCL Comprehensive Clinical Trials Unit.
