Tysabri is dangerous drug

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Drug for MS reactivates virus causing deadly brain disease

Natalizumab treatment double-edged sword for MS patients, study finds

September 10, 2009

Bonnie Prescott

Beth Israel-Deaconess Medical Center

The virus responsible for progressive multifocal leukoencephalopathy (PML), a

rare brain disease that typically affects AIDS patients and other individuals

with compromised immune systems, has been found to be reactivated in multiple

sclerosis patients being treated with natalizumab (Tysabri). The findings by

Harvard researchers at Beth Israel Deaconess Medical Center (BIDMC) and

collaborators at s Hopkins University, are published in today's edition of

The New England Journal of Medicine (NEJM).

“This virus – the JC virus, named for the initials of a patient – is found

in about 90 percent of the population,†explains Igor Koralnik , the study’s

senior author and associate professor of medicine at Harvard Medical School and

director of the Human Immunodeficiency Virus/Neurology Center at BIDMC. “But

in healthy individuals the virus lies dormant in the kidneys and causes no

problems.†Urine samples of healthy individuals may, therefore, show evidence

of the benign virus.

But, according to Koralnik, a world leader in the study of PML, among AIDS

patients and those with compromised immune systems , the JC virus can reactivate

and travel to the brain, leading to the development of PML, a destructive brain

disorder that may cause numerous neurological symptoms, including dementia ,

blindness, paralysis, and seizures. There is no cure for PML and more than half

of all PML patients die within a year of diagnosis.

Four years ago, PML was diagnosed in two patients who were participating in a

clinical trial testing natalizumab, a new drug for the treatment of multiple

sclerosis (MS). An autoimmune disease caused by the migration of the immune

system’s T lymphocytes to the brain , MS results in relapsing and remitting

neurologic dysfunction when the T lymphocytes attack the myelin , the insulating

sheath that covers the nerves.

http://harvardscience.harvard.edu/medicine-health/articles/drug-ms-reactivates-v\

irus-causing-deadly-brain-disease