Shares in Ireland’s Elan Corp have leapt on the news that the firm, together with US partner Wyeth, is going to initiate a late-stage trial for their new Alzheimer's disease treatment way ahead of schedule.

The firms said they plan to start a Phase III clinical programme for AAB-001 (bapineuzumab) for the treatment of patients with mild to moderate Alzheimer's disease, based in part on interim data from an ongoing Phase II study. However, Elan and Wyeth quickly noted that "no conclusion about the Phase II study can be drawn until the study is completed and the final data are analysed and released in 2008” and warned that “it is important to remember that Alzheimer's disease is a complex and formidable challenge, and our immunotherapeutic programs still contain inherent risks”.

Despite ending on such a cautious note, the fact that the firms are prepared to start a Phase III trial before knowing the results of a Phase II study suggests a lot of confidence in bapineuzumab, a humanised monoclonal antibody that has received fast-track designation from the US Food and Drug Administration.

There are actually two ongoing Phase II studies with the compound. The first is a randomised, double-blind, placebo- controlled, multiple-ascending dose study of four cohorts of 240 patients with mild to moderate Alzheimer’s disease, looking primarily at the safety of bapineuzumab, while the second trial is an Alzheimer’s beta-amyloid imaging study in 30 patients and is being conducted in Europe. Bapineuzumab is only one compound being studied for Alzheimer’s through the Elan/Wyeth collaboration and current programmes include ACC-001 and AAB-002. The firms equally share all costs and will do the same with any potential revenues.

Elan’s shares rose almost 19% to close at 13.91 euros on the Irish Stock Exchange on the day of the announcement, while Wyeth increased 3.6% to $58.41. The rises come as little surprise because if all goes well, bapineuzumab could be filed for approval as early as the end of 2008 and take the lead in the potentially enormous Alzheimer’s market. Competition could come from Myriad Genetics’ Flurizan (MPC-7869; R-flurbiprofen), which is already in Phase III trials.