Ireland’s Elan Corporation and Biogen Idec were boosted this morning after reporting positive results from a late-stage clinical trial of their withdrawn Tysabri (natalizumab) drug in the treatment of Crohn’s disease.

The companies say that the trial, dubbed Encore, which included 510 people with moderately to severely active Crohn’s disease, met its primary endpoint of a decrease in the Crohn’s disease activity index score and also met all of its secondary endpoints, including clinical remission at both weeks 8 and 12. Furthermore, the firms note that there were no notable differences in the overall rates of side effects or serious side effects between the Tysabri and placebo treatment groups.

“The results of the Encore study are encouraging because patients treated with Tysabri achieved a significant improvement in symptoms of this devastating, chronic immune disease,” said Lars Ekman, executive vice president and president of research and development at Elan. He added that the companies plan to share these data, together with the results of other Phase III studies of Tysabri in Crohn’s disease [[19/05/04d]], with various regulatory agencies “to determine the appropriate path forward.”

In February, the two companies halted sales of Tysabri - formerly known as Antegren - after one patient died from a rare but potentially fatal central nervous system infection and a second was believed to be infected [[01/03/05a]]. Three more suspected cases have since been identified [[04/03/05a]], [[03/06/05a]], [[14/06/05c]]. The firms are reviewing all patient records for Tysabri and expect to present their findings to the US Food and Drug Administration by the end of the summer.

Approximately one million people worldwide have Crohn’s disease, a chronic and progressive inflammatory disease of the gastrointestinal tract. Complications associated with the disease include narrowing of the intestine, obstruction, abscesses, and fistulas (abnormal channels connecting the intestine and other organs, including the skin), malnutrition and decreased growth rate in children.