DUBLIN, Ireland - Elan Corp. plc halted development of its humanized monoclonal antibody, Antegren, for application in an acute multiple sclerosis (MS) setting, following the release of preliminary Phase II data.

However, Elan, of Dublin, will continue development of the drug for chronic treatment of MS and for treatment of Crohn's disease.

"In acute, it was difficult for all sorts of reasons to see what we needed to see," said Thomas Lynch, Elan's chief financial officer. It took three to four weeks to detect a therapeutic effect in humans, whereas animal models had previously indicated activity within one week.

Antegren binds a white blood cell-associated integrin molecule that promotes cell trafficking across endothelial barriers. Patients in the study received a single dose of the drug within 96 hours of the onset of an MS flare. The effect of the drug was assessed using the Kurtzke Expanded Disability Status Scale (EDSS) at baseline, 72 hours, and at weeks one through four, six eight and 14. Analysis of the data from the first four weeks indicated no statistically significant change in EDSS from baseline to week one, which was defined as the primary endpoint.

However, the clinical data were consistent with an earlier study. Both suggested "Antegren may have a beneficial effect in suppressing new lesion formation if administered chronically," according to Elan. Lynch said Phase II/III trials will commence in the fall, and a full Phase III investigation probably will go ahead next year. Elan recently reported second quarter net income of US$80.1 million, or US$0.29 per share, on revenues of US$234.4 million.