As expected, Biogen Idec and Elan have amended the label of their multiple sclerosis med Tysabri. Some 23 cases of the scary brain infection progressive multifocal leukoencephalopathy have emerged since 2006--more than are strictly accounted for in the label's current risk assessment. The companies have been working with FDA on a new label and are dealing with European regulators on a safety review as well.
U.S. risk information will be updated to warn that the risk of PML increases as the duration of treatment increases. From 24 to 36 months, the risk is about the same as the rate now on the label, or 1-in-1,000. After that, presumably, the risk would increase, but as the new label notes, "[t]here is limited experience beyond three years of treatment."
An analyst at Ireland's Goodbody told PharmaTimes that the label change was "fairly benign," adding that it doesn't require or even suggest that patients go on a so-called "drug holiday" after a certain length of treatment. That's good news for the companies, which depend heavily on Tysabri for growth. Now we'll have to see what the Europeans decide.