Quoted from http://www.baltimoresun.com/health/sns-rt-us-fda-warning-novartis-20130829,0,7614928.story
US FDA probes brain infection in patient on Novartis's MS drug
11:40 a.m. EDT, August 29, 2013
(Reuters) - The U.S. Food and Drug Administration said it was investigating a case of a rare and serious brain infection that developed in a patient in Europe, who was being treated with Novartis's multiple sclerosis drug, Gilenya.
The FDA said this was the first instance of the infection, called progressive multifocal leukoencephalopathy (PML), being reported in a Gilenya patient, who had not previously received Biogen Idec's Tysabri. (http://r.reuters.com/xuc72v)
Tysabri is another multiple sclerosis (MS) drug associated with a high risk of PML. Demand for the drug has slowed due to concerns over the potentially fatal infection.
Novartis considered the infection unlikely to be attributable to Gilenya and had informed the FDA of the infection in July, the company said in an email to Reuters.
Novartis said the infection was unlikely to be related to Gilenya given the patient's relatively short 7-month exposure to the drug, atypical MRI lesions present before being treated with the drug and repeated exposure to corticosteoroids.