NEW ORLEANS, MAY 18, 2004 Elan Corporation, plc and Biogen Idec announced that in a Phase III maintenance study, ANTEGREN (natalizumab) maintained clinical response and remission rates throughout six months among patients with Crohn's disease (CD) who had previously achieved clinical response. Additionally, a majority of natalizumab-treated patients who were also on chronic corticosteroid therapy were able to withdraw from corticosteroids and maintain response in contrast to those patients on placebo. The findings of ENACT-2 (Evaluation of Natalizumab As Continuous Therapy) will be presented for the first time at the Digestive Disease Week (DDW) annual meeting in New Orleans.

Crohn's disease, a chronic, progressive immune-mediated disease of the gastrointestinal tract, can cause a range of debilitating symptoms such as severe diarrhea, cramping or abdominal pain and malnutrition. Current treatment options for the disease are limited.

"The results of ENACT-2 suggest the potential of natalizumab as a maintenance therapy for patients with Crohn's disease," said William J. Sandborn, MD, professor of medicine at the Mayo Medical School. "This study demonstrated sustained clinical response and remission rates throughout six months on natalizumab. It also showed that natalizumab may help patients eliminate or reduce concomitant use of corticosteroids from their chronic treatment regimen. These results and the other clinical data presented at DDW are very exciting, and support the continued development of natalizumab as both an induction and maintenance treatment."

ENACT-2 STUDY FINDINGS
ENACT-2 assessed 339 natalizumab-responders from the induction study ENACT-1 (a 3-month study in patients with active CD) for the effect of natalizumab as a maintenance therapy. In the international, multi-center, double-blind, placebo-controlled tria
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Contact: Amy Losak
amy.losak@ketchum.com
646-935-3917
Ketchum
18-May-2004