Three New Cases of Brain Inflammation Linked to Tysabri, Confirms FDA

Three new cases of a rare brain inflammation have been linked to Tysabri, a prescription medication used to treat multiple sclerosis, confirmed the Food and Drug Administration (FDA).

The new cases of progressive multifocal leukoencephalopathy (PML), a rare viral disease characterized by damage to the myelin that covers and protects nerves in the white matter of the brain, are the first confirmed cases of the condition since June 2009.

Following the previous approval of the medication in November 2004, Tysabri was removed from the market the following year after reports of patients developing PML surfaced.

The drug was released for use again in July 2006 and, according to Biogen Idec Inc., marker of the drug, the medication is used by 43,000 patients. Since then, the FDA notes that 13 cases of PML related to Tysabri have been reported and confirms the link between development of PML and the use of Tysabri.

According to the FDA, the risk of developing PML seems to increase as the number of infusions of Tysabri increase. The rate of patients who have developed PML after receiving upwards of 24 infusions range from .4 to 1.3 patients per 1,000.

Multiple sclerosis, the condition treated by Tysabri, is an autoimmune disease that affects the communication between the nerve cells in the brain and those in the spinal cord, resulting in a myriad of symptoms ranging from involuntary eye movement to muscle spasms and difficulty speaking.