News Release

Alexion and Yale discover harmful complement activation in patients with acute coronary syndrome

Peer-Reviewed Publication

Noonan/Russo Communications

NEW HAVEN, CONN, March 13, 2000 -- Scientists from Alexion Pharmaceuticals Inc. (Nasdaq: ALXN) and Yale University School of Medicine, both of New Haven, CT, today reported they have discovered that patients with acute coronary syndrome (ACS) have severe inflammation including significant production of injurious complement components in their coronary arteries. The report was made at the Scientific Sessions of the American College of Cardiology. Alexion's two C5 Complement Inhibitors, the humanized monoclonal antibody fragment 5G1.1-SC and the humanized monoclonal antibody 5G1.1, specifically block the production of harmful complement components and may be useful for treatment in this patient population.

"The current study demonstrates that harmful complement activation occurs specifically in the coronary arteries of patients with acute coronary syndrome," stated Michael W. Cleman, M.D., Professor of Medicine and Director of the Interventional Cardiology Service at Yale, and co-author of the study. "While current therapies for ACS patients are directed at attempting to improve coronary blood flow with anti-platelet and anti-clotting agents, an increasingly prominent literature demonstrates that ACS patients may also suffer from severe inflammation. The current findings add significantly to these previous observations by demonstrating that severe and injurious complement activation occurs specifically in the coronary circulation and in the culprit coronary artery in patients with ACS."

In the findings presented by Dr. Cleman and his colleagues at Yale and Alexion, blood samples from 11 patients with acute coronary syndrome and four patients with stable angina were obtained in order to measure production of activated complement directly in the heart. In patients with ACS, the level of activated complement increased by approximately 70% (P=.06) in the heart. In the patients with stable angina, the level of activated complement increased by approximately 16% in the heart. Further, samples of the blockages in the affected heart blood vessels were obtained with atherectomy catheters. In all eight examined ACS patients who underwent atherectomy, severe complement activation was directly observed in the blockage from the culprit coronary artery. Similar to the blood measurement findings, substantially less complement activation was observed in the blockages removed from patients with stable angina.

"This collaborative discovery by Alexion and Yale scientists significantly extends our clinical research in patients with both acute and chronic cardiac diseases," said Leonard Bell, M.D., President and Chief Executive Officer of Alexion. "These observations also further support the strong rationale for our three ongoing 1,000 patient clinical efficacy trials in cardiopulmonary bypass and myocardial infarction indications with our humanized antibody fragment 5G1.1-SC."

According to the European Society of Cardiology, there are approximately one million annual hospital admissions in the United States and Western Europe for patients with acute coronary syndrome.

Alexion's C5 complement inhibitors are designed to selectively block the production of inflammation-causing proteins in a process of the human immune system known as the complement cascade. Selective suppression of this immune response may provide a significant therapeutic advantage relative to existing therapies. Because of the generally beneficial effects of the components of the complement cascade prior to the fifth component (C5) and the greater inflammatory disease-promoting effects of the cleavage products of C5, the Company has identified C5 as a potentially effective anti-inflammatory drug target.

###

Alexion is engaged in the discovery and development of products for the treatment of cardiovascular, autoimmune and neurologic diseases caused by undesired effects of the human immune system. Alexion's two lead product candidates are currently in seven clinical development programs. 5G1.1-SC, in collaboration with Procter & Gamble, is in a Phase IIb cardiopulmonary bypass efficacy trial and in two Phase II myocardial infarction efficacy trials. 5G1.1 is in a Phase II efficacy trial for the chronic treatment of rheumatoid arthritis, a Phase II efficacy trial for the treatment of membranous nephritis and it is commencing a Phase Ib pilot study for treatment of psoriasis and a Phase Ib pilot study for treatment of dermatomyositis. This press release and further information about Alexion Pharmaceuticals, Inc. can be found on the World Wide Web at: www.AlexionPharm.com .

This news release contains forward-looking statements. Such statements are subject to certain factors which may cause Alexion's plans to differ or results to vary from those expected including unexpected pre-clinical or clinical results, the need for additional research and testing, delays in manufacturing, access to capital and funding, delays and adverse changes in development of commercial relationships and a variety of risks set forth from time to time in Alexion's filings with the Securities and Exchange Commission, including but not limited to the risks discussed in Alexion's Annual Report on Form 10-K/A for the year ended July 31, 1999. Alexion undertakes no obligation to publicly release results of any of these forward-looking statements which may be made to reflect events or circumstances after the date hereof or to reflect the occurrence of unanticipated events.


Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.