New Data Presented at ECTRIMS Congress Show TYSABRI(R) Has Sustained Effect on Relapse Rate in Multiple Sclerosis Patients Treated for up to Three Years

Source: Biogen Idec and Elan Corporation,

ZUG, Switzerland and DUBLIN, Ireland--(BUSINESS WIRE)--Biogen Idec (NASDAQ: BIIB - News) and Elan Corporation, plc (NYSE: ELN - News) announced today new data that show TYSABRI® (natalizumab) has a sustained effect on relapse rate in multiple sclerosis (MS) patients treated for up to three years. These data, presented at the 22nd Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) in Madrid, Spain, were part of long-term follow-up of TYSABRI clinical trial patients.

Patients who participated in the Phase III TYSABRI program were eligible to enroll in an open-label extension study that evaluated the therapy's long-term effects. Approximately 1,900 patients and over 200 sites worldwide participated in the extension study.

Approximately 250 of these patients remained on TYSABRI monotherapy for nearly three years. The annualized relapse rate for these patients over the three-year period was 0.23, translating into an average of one relapse every 4.3 years. This was consistent with the 0.23 annualized relapse rate seen in the two-year AFFIRM study, which represented a 68% relative reduction when compared to the two-year placebo annualized relapse rate of 0.73, as published in the New England Journal of Medicine.

"Data from this long-term follow-up study show that TYSABRI has a sustained and compelling effect on relapse rates beyond two years of treatment. The efficacy benefit of TYSABRI when considered with the management of its known risks, offers an important therapeutic option for many patients living with the debilitating effects of MS," said Paul O'Connor, MD, St. Michael's Hospital, Toronto, Ontario, Canada, lead investigator of the extension study.