Alexion Pharmaceuticals Inc. results from its Phase III PRIMO-CABG2 clinical trial with pexelizumab show that the drug reduced the primary endpoint, but did not meet the pre-specified threshold for statistical significance. The primary endpoint was the combined incidence of nonfatal myocardial infarction (heart attack) or death through 30 days following coronary artery bypass graft (CABG) surgery in moderate-to-high risk patients.

Pexelizumab, a terminal complement inhibitor, is a monoclonal antibody fragment that inhibits complement-mediated tissue damage. The Phase III trial titled Pexelizumab for Reduction of Infarction and Mortality in Coronary Artery Bypass Graft Surgery 2 (PRIMO-CABG2), included approximately 4,250 patients, and compared the safety and efficacy of pexelizumab against that of placebo in reducing heart attack and death following CABG surgery with or without concomitant valve surgery.

Alexion expects that the trial results will be presented at an upcoming scientific meeting. The trial was conducted at approximately 250 US and international study sites, and was sponsored jointly by Alexion and Procter and Gamble Pharmaceuticals, states a company release.

“We are clearly disappointed that pexelizumab did not meet its primary endpoint in PRIMO-CABG2,” said Leonard Bell, chief executive officer of Alexion. “We look forward to completing an analysis of the data and obtaining a more in-depth understanding of these results.”

Alexion is assessing the implications of the results of PRIMO-CABG2 on its second international pivotal phase III study of pexelizumab, the APEX-AMI trial, which is investigating the benefits of using pexelizumab in patients experiencing a heart attack who are treated with primary percutaneous coronary intervention (PCI), or angioplasty. The APEX-AMI trial has enrolled over 3,000 patients at more than 300 US and international study sites.

Alexion remains on track to complete treatment in the Triumph Phase III pivotal trial with its lead drug candidate eculizumab in the orphan blood disorder paroxysmal nocturnal haemoglobinuria (PNH). Alexion expects topline results from Triumph during the first quarter of 2006.

Alexion is engaged in the discovery and development of therapeutic products aimed at treating patients with a wide array of severe disease states, including haematologic and cardiovascular disorders, autoimmune diseases and cancer. Alexion's two lead product candidates, pexelizumab and eculizumab, are currently undergoing evaluation in several clinical development programmes, including two Phase III trials of eculizumab for the treatment of paroxysmal nocturnal haemoglobinuria (PNH), a Phase III trial of pexelizumab in coronary artery bypass graft (CABG) surgery patients undergoing cardiopulmonary bypass (trial completed), and a Phase III trial of pexelizumab in acute myocardial infarction (AMI) patients.