It is unclear whether Elan and Biogen Idec's multiple sclerosis drug Tysabri may raise the risk of a rare, life-threatening brain infection when used alone, US Food and Drug Administration staff said today.
It is unclear for which patients the risk-benefit profile would be acceptable,' the FDA staff said in a report released ahead of an advisory panel review of the drug that starts tomorrow.
The companies should implement a mandatory programme to monitor risks should the drug be allowed to return to the market, the FDA recommended.
Elan is to suspend trading in its shares during the two-day US FDA review of Tysabri. The company's shares trade on the Dublin Stock Exchange, the New York Stork Exchange and in London.
Tysabri sales were suspended in February 2005 after three patients developed a rare brain and spinal-cord infection known as progressive multifocal leukoencephalopathy, or PML. Two of them died. In two of the cases, patients were also taking another Biogen drug, Avonex, at the same time, which led to theories that use of Tysabri alone might be less risky.
Biogen, in a statement, said Tysabri was highly effective and MS patients should be able to decide for themselves whether the drug's risks are acceptable.
Elan shares closed 39 cent higher at €10.60 in Dublin this evening - a gain of almost 4%.
