Investor Update

Basel, 31 August 2005

Biogen Idec and Genentech submit a supplemental Biologics License Application for FDA review of Rituxan for the treatment of rheumatoid arthritis

Dear Investor,

Please see the news release of Biogen Idec and Genentech announcing the submission of a supplemental Biologics License Application with the FDA for a new indication for Rituxan.

Please do not hesitate to contact us if you have any further questions.