Biogen, FDA work to amend Multiple Sclerosis drug Tysabri's label 26 August 2008
A warning on Biogen Idec and Elan Corp's drug, Tysabri, has been revised following two recent reports of a potentially fatal brain infection, Biogen said.
The company plans to provide an update on the two patients on today at a medical conference in Madrid, Biogen spokeswoman Shannon Altimari also said.
Still, both companies were down sharply since they disclosed on July 31 that two more patients had developed progressive multifocal leukoencephalopathy, a brain disorder known as PML that is usually fatal.
The FDA, in an alert to doctors posted on Monday on its website, said the agency had been told of the two newest PML cases and was "working with the manufacturer to amend the product labeling."
Biogen's Altimari said prescribing instructions were changed last week to note that PML had been reported in patients using Tysabri as their sole treatment for multiple sclerosis.
The two recent cases involved patients in Europe who were using Tysabri as "monotherapy," or stand-alone treatment, for more than a year.
"While the two patients who developed PML were on monotherapy, the FDA still believes that Tysabri monotherapy may confer a lower risk of PML than when Tysabri is used together with other immunomodulatory medications," the FDA said. Previously, PML had been seen in patients using Tysabri with other medicines to control MS. Tysabri was withdrawn in 2005 amid three cases of PML, but returned to the market in 2006 with warnings and tougher prescription guidelines.
New language on Tysabri's label notes that PML incidence "appears to be lower" with monotherapy, but adds "the number of cases is too few and the number of patients treated too small to reliably conclude that the true risk of PML is lower in patients treated with Tysabri alone."
The changes "were made with the FDA's concurrence," agency spokeswoman Sandy Walsh said late on Monday.
About 39,000 patients have been treated with Tysabri worldwide, with about 12,000 patients using the drug for at least a year, the FDA said.
Tysabri, known generically as natalizumab, is approved for treating multiple sclerosis and the bowel disorder Crohn's disease. It is given by injection.
Biogen plans to provide an update on the condition of the two patients with PML at the European Federation of Neurological Societies in Madrid on Tuesday, Altimari said.
Source: guardian.co.uk © Guardian News and Media Limited 2008