Biogen withdraws 2005 financial forecast

Biogen has withdrawn its 2005 earnings forecast as it can no longer count on revenue from its suspended multiple sclerosis drug Tysabri.

Biogen shares have fallen nearly 50 per cent since Biogen and Tysabri partner Elan suspended sales of the new drug after a patient developed a rare but potentially fatal nervous system disorder.

Tysabri, approved in the United States last November, was widely expected to become the world's leading treatment for multiple sclerosis and an important driver of growth for both Biogen Idec and Elan.

But a second patient was later also diagnosed with the disease, progressive multifocal leukoencephalophathy (PML), and the companies said a third patient had been diagnosed with the condition. Many are now skeptical Tysabri will ever return to the market.

Bill Rastetter, Biogen's executive chairman, told investors at a Lehman Brothers conference that the company will continue to manufacture the drug, albeit a reduced rate, while it completes its examination into why patients developed PML while taking Tysabri.

"We hope to report on the results of this evaluation in the second half of the year," he said.