A new hope for Parkinson’s disease? A French scientific research team has announced promising results in its work to fight the condition using a medication that is already used for Type II diabetes.
The world-first study was published in the medical journal the New England Journal of Medicine.
“These results are very positive, because for decades we have been looking for medicines that could have this type of neuroprotective effect," said Professor Olivier Rascol, neuropharmacologist at the Toulouse University Hospital, and Prof Wassilios Meissner, neurologist at Bordeaux University Hospital, who co-led the study.
Parkinson’s disease is linked to the loss of neurons that produce the chemical dopamine, which is essential for voluntary movement regulation in the body. As the disease progresses, these neurons disappear, leading to a dopamine deficit, and the appearance of symptoms.
Symptoms include tremor (shaking), often in the hand or arm; slow movements; muscle stiffness and cramps. These can make it difficult to walk, talk, or do normal activities unaided.
Treating the cause not just the symptoms
Currently, patients are usually treated with dopamine substitutes.
“These drugs only treat the consequences of dopamine deficiency, not the causes of the disease. They have no long-term neuroprotective effect," said Prof Rascol.
However, this new research has focused on lixisenatide, a chemical belonging to the same family as semaglutide (an anti-diabetic drug that is beginning to be used successfully against obesity, for example under the brands Ozempic and Wegovy).
In this study, lixisenatide showed promising abilities to address the root cause of the dopamine deficiency, and slow the onset of Parkinson’s, researchers said.
“This is the first study in 30 years to show unequivocally that we can have an impact on the progression of the disease," said Prof Meissner.
Research project
The study included 156 patient volunteers, all of whom had been diagnosed within the last three years, and aged between 40 and 76. All work took place at the 21 centres belonging to NS-Park, the French clinical research network for Parkinson's disease.
Half of the participants received lixisenatide, while the other half received a placebo. All took a dopamine substitute. The drug was provided for the trial by French lab Sanofi.
After one year, the results showed that the patients taking the placebo had worsened symptoms, including more difficulty walking and moving, greater intensity of tremors and stiffness.
In contrast, the patients treated with lixisenatide did not see any worsening of symptoms. This effect remained even two months after they stopped taking the medicine.
“We think that the drug slows down the loss of dopaminergic neurons,” said Prof. Rascol. “If this hypothesis proves to be true, this anti-diabetic drug could play a crucial role.
“We know that patients suffering from diabetes have an increased risk of developing Parkinson's disease,” he added. “But we found that the risk was lower in those treated with a drug such as lixisenatide.”
The researchers have suggested that this could be because Parkinson’s is partly a result of the accumulation of a protein, alpha-nuclein, which induces the death of neurons, as well as inflammation, which worsens the loss.
"We think that one of the effects of lixisenatide is to reduce the harmful consequences of inflammation on the functioning of neurons,” said Prof. Meissner.
‘Too early to change practices’
However, the researchers said that it was still too early to “change practices” and put “all patients on lixisenatide”.
More studies are still needed “to confirm these data by testing other doses of the drug, over longer periods and with more patients”, said Prof. Rascol.
It is also unclear whether the drug would have an effect on people who were diagnosed with the condition more than three years ago.
Similarly, lixisenatide can also cause side effects, including nausea, and - in rare cases - pancreatitis.
“This happened to one of our participants,” said Prof. Rascol. “As we knew it could happen, we monitored the risk closely and were able to stop the treatment in time. There were no consequences this time, but the risk should not be ignored.”
Currently, lixisenatide is not available on the wider market in its simple form, the professors added. It is only sold in a form combined with insulin, which would not be suitable for Parkinson’s patients who do not also have diabetes.
The professors are aiming to resolve these issues as soon as possible, so that phase three of the study can begin. Anyone who may be interested in taking part in the trial can keep an eye on the professors’ work by contacting the NS-Park network, said Prof. Rascol.
