WASHINGTON An experimental vaccine against multiple sclerosis appears to be safe and may produce beneficial changes in patients' brains and immune systems, Canadian researchers reported on Monday.
Some patients appeared to have fewer immune cells attacking their nerves, a hallmark of MS, the researchers report in the Archives of Neurology. They also appeared to have fewer lesions in their brains.
The study was designed only to show that the vaccine was safe, and it is safe enough to continue phase 2 trials, which begin to look at whether it works, the researchers said.
In multiple sclerosis, the immune system mistakenly attacks the fatty myelin sheaths that protect nerve cells in the brain and spinal cord.
There is no cure for the disease, which affects an estimated 400,000 people in the United States alone, according to the National Multiple Sclerosis Society. Symptoms include blurred vision, loss of balance, poor coordination, extreme fatigue, paralysis and blindness.
Dr. Amit Bar-Or of the Montreal Neurological Institute and colleagues tested the vaccine, called BHT-3009, in 30 patients.
The vaccine is made by Bayhill Therapeutics, a Palo Alto, California-based biotechnology company, which also paid for the study. A so-called therapeutic vaccine -- designed to treat a condition, not to prevent infection -- it targets the misguided immune system cells, called CD4 T-cells, that attack myelin.
The patients got regular magnetic resonance imaging scans up to nearly a year after the first injections.
"BHT-3009 was safe and well tolerated, provided favorable trends on brain MRI and produced beneficial antigen-specific immune changes," the researchers wrote. These changes included fewer immune cells programmed to target myelin, they said.
The company has already begun a phase 2b trial of the vaccine in 290 MS patients.
"If successful in MS, antigen-specific DNA vaccines can be developed for prevention or treatment of related diseases, such as type 1 diabetes mellitus, systemic lupus erythematosus, rheumatoid arthritis and myasthenia gravis," the researchers wrote.