September 18, 2013 — At least six Tysabri lawsuits have been filed in Massachusetts and there other states, according to the Boston Globe. Plaintiffs allege that drug-makers failed to warn that the longer a patient takes Tysabri, the greater the risk of a severe, life-threatening brain infection called progressive multifocal leukoencephalopathy (PML).
One lawsuit was filed by Kimberly A. Yout, a woman who was diagnosed with PML after taking Tysabri to treat Multiple Sclerosis (MS). She now suffers from trouble walking, slurred speech, blindness in one eye, and cognitive impairment that makes normal activities and independent living impossible.
Tysabri has been prescribed to at least 118,000 people, of whom 395 have developed PML and 92 have died. The FDA and drug-makers maintain that the benefits of Tysabri outweigh the risk of PML. In August, the FDA warned that another MS drug, Gilenya, was linked to one case of PML.
Biogen Idec and Elan, the pharmaceutical companies behind Tysabri, pulled the drug off the market in 2005 after two fatal cases of PML were reported. Tysabri returned to the market in 2006 with stronger warnings.
Tysabri and PML (Brain Infection)
PML is a rare infection of the white matter. The disease targets cells that make myelin, which is the insulating layer around neurons. People with PML can suffer permanent nerve damage and death. It is caused by the JC virus, which is normally harmless. The JC virus can cause PML in people on Tysabri and other immunosuppressant drugs.
Risk-factors for PML on Tysabri include:
- People who have taken immunosuppressant drugs before
- People who have used Tysabri for at least two years.
- People who are infected with the JC virus