A new study has found that a drug used to treat Parkinson's disease is able to safely slow the progression of an incurable form of motor neurone disease for over six months.
Clinical trials showed that ropinirole delays the symptoms of Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease. It claimed the life of cosmologist Stephen Hawking.
ALS, which does not have a cure, causes people to gradually lose control of their muscles. At the moment, treatments focus on reducing the symptoms and providing supportive care.
But now Japanese scientists have shown that ropinirole, used to treat the symptoms of Parkinson's disease and restless legs syndrome, is safe to use in ALS patients and delayed disease progression by an average of 27.9 weeks.
Some patients were more responsive to ropinirole treatment than others, according to the findings published in the journal Cell Stem Cell.
Senior author Professor Hideyuki Okano, of the Keio University School of Medicine in Tokyo, said: "ALS is totally incurable, and it's a very difficult disease to treat.
"We previously identified ropinirole as a potential anti-ALS drug in vitro, and with this trial, we have shown that it is safe to use in ALS patients and that it potentially has some therapeutic effect.
"But to confirm its effectiveness we need more studies, and we are now planning a phase three trial for the near future."
To test ropinirole's safety and effectiveness in patients with sporadic ALS, the team recruited 20 patients receiving care at Keio University Hospital.
None of the patients carried genes predisposing to the disease, and, on average, they had been living with ALS for 20 months.
The patients and doctors did not know which patients were receiving ropinirole and which were receiving a placebo for the first 24 weeks.
Then, for the following 24 weeks, all patients who wished to continue were knowingly administered ropinirole.
To determine whether the drug was effective at slowing the progression of ALS, the researchers monitored several different measures throughout the trial and for four weeks after treatment concluded.
These included changes in the patients' self-reported physical activity and ability to eat and drink independently and activity data from wearable devices.
Study first author Dr Satoru Morimoto, a neurologist at the Keio University School of Medicine, said: "We found that ropinirole is safe and tolerable for ALS patients and shows therapeutic promise at helping them sustain daily activity and muscle strength,"
He said patients who received ropinirole during both phases of the trial were more physically active than patients in the placebo group.
They also showed slower rates of decline in mobility, muscle strength, and lung function, and they were more likely to survive.
The researchers said that the benefits of ropinirole relative to the placebo became "increasingly pronounced" as the trial progressed.
However, the placebo group patients who began taking ropinirole halfway through the trial did not experience those improvements, suggesting that ropinirole treatment may only be useful if treatment is started earlier and administered over a longer duration.
The researchers also found that, compared to healthy motor neurons, motor neurons from ALS patients showed distinct differences in structure, gene expression, and metabolite concentrations, but ropinirole treatment reduced these differences.
Dr Morimoto added: "We found a very striking correlation between a patient's clinical response and the response of their motor neurons in vitro.
"Patients whose motor neurons responded robustly to ropinirole in vitro had a much slower clinical disease progression with ropinirole treatment, while suboptimal responders showed much more rapid disease progression despite taking ropinirole."
The researchers say it's unclear why some patients are more responsive to ropinirole than others, but they believe that it's probably due to genetic differences that they hope to pinpoint in future studies.
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