Clinical Brief – August 22nd

The Brief

A drug approved to treat type 2 diabetes was shown to improve motor symptoms for Parkinson’s in a placebo-controlled trial.

What does the Fox say?

In a pilot trial funded by the Michael J Fox foundation, about 60 patients with moderate Parkinson’s currently on treatment with wearing-off effects received either a diabetes treatment, exenatide extended-release (Bydureon), or a placebo. They also stayed on whatever medication they took before joining the trial.

For a charity-funded trial, this was surprisingly well done: Randomized patients, double-blinded design with multiple processes in place to minimize the risk of unblinding, and a full 48 weeks of treatment. Patients were followed up again after treatments were stopped for 12 weeks.

The primary measure was an evaluation of motor signs of Parkinson’s using a scale which has been called the “objective assessments of parkinsonism”. Simply put, it’s a scale of 0 to 137 where 0 means no symptoms and 137 means severe symptoms on all assessments.

Patients on placebo saw their motor symptoms worsen from 27 before the trial, to 29 after 48 weeks of treatment. On the other hand, those taking exenatide saw their symptoms improve from 33 to 30, significantly outperforming placebo.

The same measurements were made again after all patients were taken off of their treatments for 12 weeks thereafter. Patients who took exenatide had symptoms scored at 32 – still better than the 33 they started with; vs 29 for placebo, which was worse than the 27 they started with.

The researchers also looked at the effect of treatment on cognition, twitching, mood, and quality of life. Here, they found no significant differences between patients who took exenatide or placebo on all these assessments.

Bottom line

This trial was very encouraging, particularly since the effects of exenatide can be seen even after the treatment stopped.

Does this mean exenatide is ready for clinical use? Probably not yet.

For one, 60 patients from a single hospital in London is too small a sample to claim that exenatide works for Parkinson’s.

“A long-term simple multi-site trial design will be necessary to establish the long-term effects of exenatide treatment on daytime function in Parkinson’s disease.”

– Athauda D, et al.

But a silver lining to this is that exenatide is the oldest diabetes drug in the so-called GLP-1 class. This means that lower-cost generics are on their way.

The formulation of exenatide used in this trial was a once-weekly dose, but an older twice-daily formulation is expected to go off patent in the US this October. Maybe this can help offset some of the costs of a larger trial?


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