Use of MS drug predicted to slow because of deadly side effect

From The Boston Globe:

Financial analysts are predicting the number of patients using Tysabri will fall far below Biogen Idec Inc.'s forecast, following the Cambridge biotech company's disclosure last week that two more patients using the multiple sclerosis drug contracted a potentially fatal brain disease.

In an investor note today, Deutsche Bank analyst Mark Schoenebaum said that even under his best scenario, Tysabri will only have about 75,000 patients by 2013, far short of the company's goal of 100,000 by 2010. In a more conservative scenario, Schoenebaum predicts just 56,000 patients will use the drug by 2013. And in the worst case, he said, the drug could get pulled from the market if more safety problems emerge.

Close to 32,000 patients are currently using the treatment, which has been approved by the Food and Drug Administration to treat both multiple sclerosis and severe forms of Crohn's disease.

Still, JP Morgan analyst Geoffrey Meacham wrote in a note last week that even before the news of two new cases of the brain disease, called PML, Wall Street's forecasts for the numbers of Tysabri patients by 2010 had been half of Biogen Idec's predictions. Based on that, Meacham wrote, analysts' estimates will probably not fall dramatically further.

Biogen Idec shares rights to Tysabri its Irish partner, Elan Corp. Both companies stocks were pounded last week after the disclosure of the new PML cases, even though Biogen Idec and has long warned that PML is a possible side effect of Tysabri use.