Biogen Idec on Friday withdrew its 2005 financial forecast as a result of the withdrawal of its much-touted multiple sclerosis drug, Tysabri (natalizumab) [[01/03/05a]].

In a statement, the US firm said that investors should no longer rely on the financial guidance issued in February of earnings per share of between $1.60 to the low $1.70s, versus $1.44 in 2004 [[08/02/05b]]. The company's results had been expected to be buoyed by sales of Tysabri, which had been set to be a major contributor to both Biogen and partner Elan Corporation’s earnings, with sales ultimately forecast to break the $1 billion dollar barrier.

However, the companies suspended sales and clinical trials of the product in February after two cases of progressive multifocal leukoencephalopathy – a rare and potentially fatal immune system disease – were reported [[01/03/05a]]. One of the patients in question died from the condition.

Biogen Idec’s share price moved little on the latest news, but the firm’s shares have lost almost half of their value since the Tysabri suspension. The firm is currently languishing around the $34.74 mark, after hitting a new year-low last Thursday after the firm and Elan confirmed that a second patient had died from PML [[31/03/05a]].