The greatest unmet need of people with Parkinson’s disease is a therapy to slow or stop progression. A treatment to reverse the symptoms would be the Holy Grail. So when researchers from Georgetown University announced findings in that direction at the Society for Neuroscience meeting over the weekend, people with Parkinson’s were understandably enthusiastic.
The scientists reported that their small trial (12 patients) of a cancer drug showed substantial improvement of symptoms and evidence of impact on the disease biology.
We asked MJFF Scientific Advisory Board member David Weiner, MD, what the findings mean for Parkinson’s patients and research. His take: interesting with good scientific rationale but with study design limitations and no data out yet to analyze.
The drug, nilotinib, works to stimulate the cellular clearance system or “garbage disposal.” In leukemia, it helps clear out cancer cells. In Parkinson’s nilotinib may help dispose of the toxic protein clumps that lead to dopamine cell death.
“The drug was never made to get into the brain; this was made for a peripheral cancer,” said Dr. Weiner. “The question is if you could safely give enough of this drug to get into the brain to be efficacious.”
The Georgetown researchers presented that they saw a significant reduction in protein levels, including alpha-synuclein, in spinal fluid (a proxy measure for impact in the brain), but detailed data has not been released. That information will tell more about the drug’s potential impact on the Parkinson’s process.
Researchers also reported a significant impact on motor symptoms and cognition. However, everyone in the study knew they were getting the drug (open label). The gold standard for drug efficacy trials is double-blind where neither the participant nor the investigator knows who is receiving the drug and who is getting a placebo. That design aims to prevent bias.
“We know historically that there’s a huge placebo effect with Parkinson’s open label trials,” says Dr. Weiner. “You have to be extremely cautious with interpretation of open label trial data in Parkinson’s.”
Finally, participants in the trial took the drug for six months but, if it came to market, people with Parkinson’s would have to take it for the rest of their lives.
“The results so far suggest that the drug is promising, yet one of the biggest outstanding issues is if chronic treatment with a drug like this is safe in a Parkinson’s population, and this study wasn’t designed to answer that question. The study does suggest that it may be worthwhile to design and conduct future studies to answer that question,” said Dr. Weiner.