Experimental MS Vaccine Proves Safe in Early Test
Monday, August 13, 2007; 12:00 AM
MONDAY, Aug. 13 (HealthDay News) -- An experimental DNA vaccine to fight multiple sclerosis is safe and may also be effective, results of a small Canadian trial suggest.
The vaccine, called BHT-3009, works by preventing the immune system from attacking the myelin sheaths that protect nerve cells in the brain and spinal cord. The destruction of myelin eventually destroys a nerve cell's axon, which prevents cells from transmitting messages and is one of the hallmarks of MS.
"This was an early trial of a new class of drugs for autoimmune disease in general and for MS in particular," said lead researcher Dr. Amit Bar-Or, of McGill University's Montreal Neurological Institute.
The idea of the vaccine is to change the immune cells that target the nervous system, Bar-Or said. "What we want to do is focus on just those cells that are involved in the disease process," he said. "So antigen-specific therapies are designed to try to modify or eliminate only those bad-guy cells that are involved in the disease process."
The vaccine makes use of a backbone of DNA onto which is attached myelin basic protein, which is a component of myelin. When you inject it, the vaccine reduces the body's ability to attack myelin, Bar-Or explained.
The findings were published online Monday inArchives of Neurologyand were expected to be published in the October print issue of the journal.
According to the National Multiple Sclerosis Society, the disease's symptoms are unpredictable and vary from person to person, and even from time to time in the same person. One person may experience abnormal fatigue, while another might have severe vision problems. A person with MS could have loss of balance and muscle coordination, making walking difficult. Another person could have slurred speech, tremors, stiffness and bladder problems.
In the new study, Bar-Or and his colleagues gave the vaccine to 30 patients with relapsing-remitting MS, which is characterized by alternating periods of symptoms and then relief from those symptoms. At one, three, five and nine weeks, the study participants received injections of BHT-3009 or a placebo. After 13 weeks, those who had been given a placebo were given four injections of BHT-3009.
The researchers evaluated the patients using MRI scanning. They found that the vaccine was well tolerated and also appeared to produce antigen-specific immune changes that stopped the destruction of myelin. These changes were seen in the reduction in the number of CD4+ T-cells -- white blood cells that target myelin.
Bar-Or cautions that much more work remains to be done to see if the vaccine is effective. Whether it represents a possible cure is unknown; all that is known right now is that it's safe. "The trial did provide a biological proof of concept, he said. "In addition, there are other targets in the brain that are involved in MS.
"Now that this biological principle appears to be sound, one could develop DNA vaccines to different targets," he said. "Ideally one could develop a cocktail that deals specifically with an individual's MS."
Based on theses findings, the Montreal researchers have started a phase 2 trial testing BHT-3009 on 290 patients with MS.