Parkinson's - cautious optimism
Diabetes drug clears new hurdle
“Parkies”, as we people with the world’s fastest growing neurologocal disease sometimes call ourselves, have learned to be cautious about the hunt for a cure. The wonder drug that can slow, stop or even reverse the progress of Parkinson’s seems to be forever five years away and promising early trials always seem to be followed by disappointment at the final stage.
Perhaps the charity Cure Parkinson’s has itself learned to be cautious because this week it seemed eager not to get too excited when it reported news from a medical conference in Copenhagen. At the International Parkinson and Movement Disorder Society researchers unveiled the results of a phase 2 clinical trial of a diabetes drug called lixisenatide. They showed that the progression of Parkinson’s movement symptoms was slowed in those taking the drug as compared with those given a placebo.
Lixisenatide is among a type of diabetes drugs called GLP-1 agonists which are amongst the most hopeful candidates in the long quest for something which halts the progression of Parkinson’s rather than merely masking the symptoms. Another such drug, exenatide, is now having a phase 3 trial, having shown promising results in a phase 2 study.
The Lixisenatide researchers unveiled their results not with some grand press conference but a simple poster at the movement disorder congress, and even then there was apparently a far bigger crowd for an adjacent poster about cell replacement therapy.
So what should we think about this news? Should we be excited or cautious, especially as it is a little behind exenatide in the clinical trial process? I consulted Simon Stott, the very measured Head of Research at Cure Parkinson’s. He says the reason to get excited about lixisenatide is that its phase 2 trial was much bigger than that for exenatide.
“It involves 21 sites across France and 156 people, so a very large study, and there's not simply one investigator involved. There’s lots of investigators involved, and they see something interesting in the results.”
The reasons to be cautious are that we don’t have the full results of this trial yet - they will come early next year - and two other trials of GLP-1 agonists, one by an American drug company, another by a Koreean business, did not produce positive results.
Still, both lixisenatide and exenatide are known to be safe drugs readily available for treatment of diabetes, so it is not unreasonable to think that people with Parkinson’s who are not diabetic might try to get hold of them. After all, even if the phase 3 exenatide trial is successful it is unlikely to be available to prescribe before 2025.
But here is another reason for Simon Stott to be cautious. The best known and most easily available GLP-1 agonists are weight loss drugs such as liraglutide . The concern is that people who rush to buy them in the hope they will halt their Parkinson’s could end up doing themselves harm:
“We're worried about what's called the Kardashian effect, where you have a lot of Hollywood celebrities going around telling everyone how wonderful a drug is and how much weight they're losing ... And people with Parkinson's can't really afford to have that weight loss.”
There is one more twist to this tale. Both Astra Zeneca, which markets exenatide, and France’s Sanofi, which sells lixisenatide, are thought to be unconvinced that they want to stay in the diabetes market. Just as they show promise as a potential breakthrough for Parkinson’s treatment, could the production lines for these drugs stop running?