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News in Brief
NINDS Releases NET-PD Results at WPC
In the first public announcement from the largest study ever conducted of treatments that may slow the advance of Parkinson's, the National Institute of Neurological Disorders and Stroke (NINDS) has said that two candidate treatments - creatine and minocycline - may merit further testing to assess their potential to treat Parkinson's disease. The announcement was made on February 23 at the World Parkinson Congress by Karl Kieburtz, M.D., M.P.H., University of Rochester, the lead investigator of the project. Based on the results, investigators recommended that creatine, a substance produced in muscle, and minocycline, an antibiotic, be studied in a larger population to determine their efficacy in treating Parkinson's.
The project, Neuroprotection Exploratory Trials in Parkinson's Disease (NET-PD), is a nationwide, multi-center effort to study compounds that may slow the progression of Parkinson's disease. The study arms involving creatine and minocycline enrolled 200 people with Parkinson's who were in the early stages of the disease and not yet taking medication. Trial participants were divided into three groups. In one, participants received 200 mg of minocycline per day; in the second, 10 grams of creatine per day and the third, a placebo. For the next 12 months, researchers monitored the study participants to examine the safety and tolerability of the two treatments, as well as any impact they may have had on Parkinson's. Although investigators noticed a decline in clinical signs of Parkinson's in participants taking either of the study treatments, they stressed that this trial was not intended to assess the usefulness of these medications. Instead, it was designed to determine if creatine or minocycline should be further examined as possible treatments for Parkinson's. (This kind of study is known as a "futility" study - that is, it is designed solely to find out whether a particular intervention is "better than useless.")
The trial showed that both treatments had no major side-effects, but that minocycline was not tolerated as well as creatine. While NINDS says it is encouraged by the results, it emphasizes that neither compound has been tested thoroughly enough for it to be recommended for patients.
Results of this study were published in the March 14 issue of the journal Neurology. The next step will be to proceed with a Phase III trial of minocycline and creatine for treating Parkinson's disease. For more information on NET-PD, visit www.parkinsontrial.org.
FDA Accepts Tasmar® Labeling Changes
Valeant Pharmaceuticals announced on February 22 that the US Food and Drug Administration (FDA) approved less restrictive labeling for Tasmar® (tolcapone), a COMT inhibitor that is an adjunct therapy to levodopa. The label change calls for less frequent laboratory testing of liver function for people who are taking the drug and raises the threshold level of liver enzymes that is acceptable for a patient to remain on Tasmar®. The FDA made this decision based on data supplied by the manufacturer from clinical trials of 3,400 Tasmar®-treated patients.
Tasmar® is used to reduce "off" time for Parkinson's patients. The drug was widely used in the Parkinson's community until 1998, when reports of liver failure experienced by people who were on the drug resulted in the addition of a boxed warning to the label. The warning reported three fatal cases of liver failure and gave several restrictions for use. The new label change indicates that while monitoring of liver function is still important, the problems experienced by some people on the drug may not be as widespread as was previously believed. Specifically, the label states that liver enzyme levels should be determined at baseline, and thereafter at every two to four weeks for the first six months that a person uses the drug. After that, monitoring is recommended at intervals determined by the treating physician.
Parkinson's Gene Mutation Found in Ashkenazi Jewish Patients
For many years, Parkinson's experts have hypothesized that the disease is caused by some combination of genetic and environmental factors. Researchers at the Beth Israel Medical Center in New York recently contributed a clue to the genetic side of the equation when they discovered a mutation on the LRRK2 gene that causes Parkinson's in the Ashkenazi, or Eastern European, Jewish population.
The team, led by senior investigator Susan B. Bressman, M.D., collected DNA samples from 120 unrelated Ashkenazi Jews with Parkinson's disease who had been screened at Beth Israel. Among this population, more than 18 percent were found to have the gene mutation G2019S, the most common LRRK2 mutation. When the group was divided into a subset of patients who reported a family history of Parkinson's, almost 30 percent showed the mutation. Researchers compared the study group to a control group of 317 Ashkenazi Jews without Parkinson's, in which only about one percent had the gene mutation. The New England Journal of Medicine published a letter to the editor on these findings in its January 26 issue.
A group of North Africans of Arab descent with Parkinson's disease has also been identified by researchers as carrying the G2019S mutation.
The Beth Israel study is the latest demonstration of the potential role that genetics may play in determining whether a person develops Parkinson's disease. Although the results represent an important step in helping scientists learn more about what causes the disease, there are currently no preventive measures that can be taken if a person is discovered to carry this or any other gene mutation that is associated with Parkinson's disease. In addition, having the mutation does not necessarily mean that a person will develop Parkinson's disease. Therefore, widespread genetic testing is not recommended at this time.