Fingolimod, a multiple sclerosis (MS) drug marketed as Gilenya, has been linked with progressive multifocal leukoencephalopathy (PML) in 2 patients, the FDA has warned (http://1.usa.gov/1Phtd18). The agency noted that information about the cases, provided by Gilenya’s manufacturer, Novartis, is being added to the drug label.
Progressive multifocal leukoencephalopathy is a rare, serious brain infection caused by the John Cunningham (JC) virus. Symptoms of PML include new or worsening weakness; clumsiness; and changes in thinking, eyesight, strength, or balance. Infection with the JC virus is harmless in most people but can cause PML in those with a weakened immune system, including patients who take immunosuppressant drugs. Magnetic resonance imaging may detect brain lesions before symptoms develop. Within the first few months after diagnosis, however, PML has a mortality rate ranging from 30% to 50% (http://1.usa.gov/1hAb584).
Voelker R. Brain Disease Linked With MS Drug. JAMA. 2015;314(11):1108. doi:10.1001/jama.2015.11140