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News in Brief
Early Data from GDNF Trial Show No Clinical Improvement
The Amgen company announced on July 1 that its widely-watched clinical trial testing the efficacy of a neuronal growth factor in treating advanced Parkinson's has failed to demonstrate any clinical improvement after six months of use.
The finding has surprised many because it seems to be at odds with an earlier, smaller "open-label" study in the U.K. that had suggested strong therapeutic potential for the compound, a protein known as glial cell line-derived neurotrophic factor (GDNF).
In a response to the Amgen announcement, Dr. Stanley Fahn, PDF's Scientific Director, acknowledged that the news will be disappointing to the Parkinson's community and to scientists but noted that, "A negative trial result does not necessarily mean that the compound in question is of no therapeutic value - especially when that compound has demonstrated promise in animal studies and earlier, smaller, human trials."
Dr. Fahn added, "A variation in the study design (e.g., different duration, different dosage, different patient selection criteria, a change in method of drug delivery) may yield different results, and should be explored before any particular approach is abandoned." He also said that disappointments of this kind in clinical trials show how important it is to remain open to all promising approaches to therapy.
In a conversation with PDF staff, Amgen officials have said that specific data from the trial will be released once analysis is complete and that a full report will be submitted for presentation at the October 2004 meeting of the American Neurological Association. At a late-summer meeting in Chicago with representatives of the Parkinson's community (including Robin Elliott of PDF), Dr. Roger Perlmutter, Executive Vice President of Research and Development of Amgen, said that despite the disappointing results of this trial, the company remains committed to doing everything it can to understand the full potential of this molecule. "We will leave no stone unturned!" he told the group.
One possible immediate step, he said, might be to work out a mechanism - perhaps through the NIH or under the auspices of a private foundation - for identifying those scientists whose research interests and capacities might be most suitable for exploring GDNF.
Vaccine Approach Prevents Progression of PD in Early Studies
A research team from the University of Nebraska Medical Center (UNMC) in Omaha and Columbia University Medical Center in New York has discovered a new vaccine that protects brain cells in a mouse model of Parkinson's disease.
The findings were published in the June 22 Edition of Proceedings of the National Academy of Sciences. The study aimed to test whether a compound called Copaxone®, used by patients with multiple sclerosis, could be used to prevent or reduce cell death in Parkinson's disease. Though the strategy has yet to be tested in clinical trials in humans, scientists believe the discovery could lead to improved treatment for people with Parkinson's and other neurodegenerative diseases.
"The research is very exciting," said Serge Przedborski, M.D., Ph.D., Professor of Neurology and Pathology at Columbia University and a world-renowned expert in Parkinson's disease research. "Using this approach, the harmful aspects of inflammation associated with Parkinson's disease could be eliminated."
While inflammation itself does not cause PD, scientists believe that when dopamine cells begin to die, an inflammatory response is triggered that increases the burden on these sick neurons. The vaccine appears to "flip a switch," inducing an immune response that blocks inflammation and helps to eliminate some factors contributing to cell death. The result could help to slow disease progression and improve the quality of life for people living with Parkinson's.
The vaccine approach, if successful, may provide an alternative to more controversial approaches for brain repair, such as embryonic stem cells and fetal cells, because it relies on harnessing the body's own immune system. Furthermore, a vaccine approach has advantages over conventional anti-inflammatory drugs, including better tolerance and fewer gastric side-effects.
The study authors emphasized that although the vaccine protects mice against the type of cell death observed in Parkinson's disease, there is no guarantee it will act in the same way in humans. Clinical trials ultimately will determine if the observations seen in mice can be translated into humans. However, the study authors anticipate that clinical trials will move forward quickly, in part because the protein in the vaccine has already been widely used and is well-tolerated in patients with multiple sclerosis. Clinical trials in humans are being developed at Columbia University.
The study was funded, in part, by the Parkinson's Disease Foundation.
Surgical Treatments Tested for Early-Stage Parkinson's Disease
In June, the Movement Disorder Society (MDS) held its 8th International Congress of Parkinson's Disease and Movement Disorders meeting in Rome, Italy. An estimated 3,500 neurologists, basic scientists and other movement disorder specialists gathered from around the world to discuss research strategies and treatments for such diseases as PD.
One scientific poster examined the potential role of deep brain stimulation surgery for early-stage Parkinson's disease. (To date, neurosurgical treatments for Parkinson's disease have been used mainly for patients with advanced, disabling symptoms.) A team of researchers led by Dr. Yves Agid at the Salpetriere Hospital, Paris, France, studied 20 patients who had experienced symptoms for only about seven years. The average age of the patients was 48.5 years. The group of 20 patients was divided randomly into two treatment subgroups: 10 patients underwent subthalamic nucleus stimulation, and 10 patients were treated using standard medications.
After one year, patients in the surgical group reported a 39 percent improvement in their quality of life, according to a rating scale, while patients in the medical group reported a six percent deterioration. Using PD rating scales to assess stiffness and slowness of movement, researchers found a 65 percent improvement in the surgical group, while the scores in the medical group worsened by about 15 percent.
The authors concluded that earlier surgical intervention might help patients with PD.However, because surgery can have a powerful placebo effect, the study is limited by a lack of placebo group. Also, among the surgical group, researchers noted a higher incidence of depression.
Next year, MDS will hold its annual meeting from March 5 to 8 in New Orleans, LA. For more information on this conference, please visit www.movementdisorders.org.
Therapy for Early and Late-Stage Parkinson's Granted FDA Approvable Letter
In early July, Teva Pharmaceutical Industries Ltd. received an approvable letter from the U.S. Food and Drug Administration (FDA) for a new Parkinson's therapy, AGILECT® (rasagiline mesylate). The treatment is recommended for use as monotherapy in early Parkinson's disease and, in combination with levodopa, as an adjunct therapy treating moderate-to-advanced Parkinson's. The letter means that while the FDA considers AGILECT® to be both safe and effective, there are remaining questions to be resolved before final approval for marketing is granted.
The once-daily AGILECT® is a "MAO-B inhibitor," which means that it stops a specific brain enzyme from breaking down dopamine before it can be used. The therapy has demonstrated potential in clinical studies in slowing the rate of impairment due to Parkinson's disease for early-stage patients and in treating freezing of gait for patients in the late stages of PD. AGILECT® is similar to the well-known Eldepryl® (selegiline), but stronger. It has the added advantage that it does not metabolize into methamphetamine (which means it should not cause sleep problems).
Now that they have the approvable letter in hand, Teva will work with FDA guidelines to obtain final approval as soon as possible. The new treatment will be co-promoted in the U.S. with Eisai Inc. as part of a long-term strategic alliance between the two pharmaceutical companies.