Parkinson’s patients who injected themselves with the diabetes therapy Byetta (exenatide) every week for a year were able to move better, according to a Phase 2 clinical trial.
Their improvement contrasted with the continued decline in the movement of the study’s control group, who received a placebo.
While the Phase 2 EXENATIDE-PD trial (NCT01971242) suggested that Byetta stopped the progression of Parkinson’s, researchers urged caution because the long-term benefits of the drug have yet to be determined.
The Michael J. Fox Foundation for Parkinson’s Research funded the study, which was published in The Lancet. The title was “Exenatide once weekly versus placebo in Parkinson’s disease: a randomised, double-blind, placebo-controlled trial,”
“This is a very promising finding, as the drug holds potential to affect the course of the disease itself, and not merely the symptoms,” Tom Foltynie, a professor at University College London’s Institute of Neurology, said in a press release. “With existing treatments, we can relieve most of the symptoms for some years, but the disease continues to worsen,” said Foltynie, the study’s lead author.
Byetta is the first glucagon-like peptide-1 receptor agonist to win U.S. Food and Drug Administration approval. It helps diabetics lower their blood sugar levels by bolstering their bodies’ ability to produce insulin.
Regulators agreed to a trial of Byetta as a Parkinson’s therapy after preclinical-trial studies showed it improved patients’ movement.
The trial at the National Hospital for Neurology and Neurosurgery in London covered 60 people with moderate cases of Parkinson’s disease. Patients were randomly assigned to receive injections of Byetta or a placebo once a week for 48 weeks. The patients on Byetta continued to take their Parkinson’s medicines during the trial.
Researchers examined patients at 48 and 60 weeks. Those who took Byetta moved better at 48 weeks, and the improvement persisted when the 12-week follow-up examinations were made.
In contrast, the placebo group’s movement declined throughout the trial. On a 132-point scale of measures such as tremors, agility, and speech, Byetta-treated patients outscored placebo patients by four points.
The study did not shed light on why Byetta benefits Parkinson’s patients, researchers said. “Whether exenatide affects the underlying disease pathophysiology or simply induces long-lasting symptomatic effects is uncertain,” they wrote.
The results spotlighted Byetta’s potential as a Parkinson’s therapy, however. That potential needs to be investigated in longer-term trials, the team said.
“This is the strongest evidence we have so far that a drug could do more than provide symptom relief for Parkinson’s disease,” Foltynie said.
“Using approved therapies for one condition to treat another, or drug repurposing, offers new avenues to speed Parkinson’s therapeutic development,” said Dr. Brian Fiske, the Fox foundation’s senior vice president of research programs. “The results from the exenatide studies justify continued testing, but clinicians and patients are urged not to add exenatide to their regimens until more is known about their safety and impact on Parkinson’s,” he added.
“While we are optimistic about the results of our trial, there is more investigation to be done, and it will be a number of years before a new treatment could be approved and ready for use,” said Dr. Dilan Athauda of University College London’s Institute of Neurology. “We also hope to learn why exenatide appears to work better for some patients than for others,” added Athauda, the study’s senior author.
Researchers’ next step will be investigating how Byetta affects other parameters of Parkinson’s. This will require longer-term studies with more participants, they said.