A drug commonly used to treat diabetes could help people living with Parkinson’s disease, say researchers.
In a clinical trial of 62 patients with the disease, a glucagon-like peptide-1 (GLP-1) receptor agonist modestly improved motor symptoms, an effect that continued once patients were no longer exposed to the drug.
In Parkinson’s disease, dopamine-producing cells in the brain are killed off, leading to progressive brain damage. Currently, drugs are available that increase dopamine levels and help patients to manage their symptoms, but they do not stop brain cells from dying and the disease continues to progress. Sufferers develop tremors, movement difficulties and eventually problems with memory.
"There's absolutely no doubt the most important unmet need in Parkinson's is a drug to slow down disease progression, it's unarguable," says one of the authors, Tom Foltynie (University College London).
Foltynie and colleagues think the current study is exciting, but they warn that the drug requires more testing before they can be certain of any long-term benefit.
For the trial, patients (aged 25 to 75 years) with idiopathic Parkinson’s disease were divided into two groups. Half were administered the GLP-1 receptor and half a placebo, once a week for 48 weeks. This was followed by a 12-week washout period.
At 48 weeks, those on placebo had declined, whereas those in the treatment group were stable. At 60 weeks, after treatment had been stopped for three months, those who had been taking the drug still had better scores on a subscale of the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) than the placebo group. In the treatment group, scores improved by an average of 1.0 point, whereas they worsened by 2.1 points in the placebo group.
Foltynie says this is the first time a clinical trial looking at Parkinson’s in actual patients has shown anything like this size of effect. The drug is not just masking symptoms, but is doing something to the underlying disease, he explains:
We have to be excited and encouraged, but also cautious as we need to replicate these findings."
Writing in The Lancet, the authors refer to the drug as representing a “major new avenue for investigation in Parkinson's disease” and call for the effects on everyday symptoms to be examined in longer-term trials.