Evelyn Pringle June 2009
On June 12, 2009, Bloomberg News reported that Biogen "said a patient taking its multiple sclerosis drug Tysabri was diagnosed with a life-threatening brain illness, the eighth case reported in the last year."
The patient was confirmed to have progressive multifocal leukoencephalopathy (PML), on June 10, according to a report Biogen’s Web site.
"PML is a progressive disease of the brain and spinal cord that primarily affects people with weakened immune systems," according to a report by WebMD Medical News.
"The condition is caused by a virus that destroys the sheath that covers the nerves," it says. "Symptoms include mental deterioration, vision loss, speech disturbances, and movement abnormalities or paralysis."
About 400,000 Americans are believed to have MS. It is more common in women than men and usually strikes between the ages of 20 and 50, according to the National Multiple Sclerosis Society. The disease causes the body’s immune system to rebel by attacking, inflaming and damaging its own nerve tissue.
Tysabri is also "approved to induce and maintain clinical response and remission in adult patients with moderately to severely active Crohn's disease (CD) with evidence of inflammation who have had an inadequate response to, or are unable to tolerate, conventional CD therapies and inhibitors of TNF-alpha," according Biogen's Website
"Other drugs linked to PML include Roche’s Cellcept, used to prevent transplant rejections; Biogen and Roche’s cancer drug Rituxan; and Genzyme Corp.'s leukemia drug Campath," according Bloomberg.
Genentech announced the removal of the psoriasis drug Raptiva from the US market on April 9, 2009, because of a link to PML. Since October 2008, three patients were diagnosed with PML and two died, Bloomberg reports.