Yale, Brigham and Women’s Hospital, And Alexion Report Potential New Treatment For Asthma

CHESHIRE, Conn., May 12 /PRNewswire-FirstCall/ -- Researchers may have found a new way to fight asthma.

The results of a new study show that treatment with an anti-C5 complement blocking antibody significantly reduced the bronchial inflammation and airway constriction that prompts asthma’s hallmark symptoms -- shortness of breath, chest tightness and wheezing. The study, conducted in animal models by researchers at Alexion Pharmaceuticals, Inc. , the Yale University School of Medicine and the Brigham and Women’s Hospital, will be published in the June 2005 issue of the Journal of Clinical Investigation. It was made available online today.

Alexion believes that these results may help position eculizumab, its lead chronic anti-C5 complement blocking antibody drug currently in late stage clinical trials, as a clinical candidate for treatment in severe asthma.

“As we aim to complete clinical development of eculizumab in the orphan blood disorder PNH, and we further assess additional potential indications for eculizumab therapy, this collaborative effort is very supportive of the potential role for eculizumab therapy in the treatment of severe, treatment- resistant asthma,” said Leonard Bell, M.D., Chief Executive Officer of Alexion.

Eculizumab, one of a new class of drugs called complement inhibitors, works by blocking activity of the C5 protein of the complement cascade. Complement is a complex series of blood proteins that work in concert with antibodies; the complement cascade refers to the precise series of events which activate each component of the complement system. As an anti-C5 complement antibody, eculizumab blocks C5 breakdown into its inflammatory components, C5a and C5b-9.

The study demonstrated that both C5a and C5b-9 contribute to the initiation of airway inflammation and in immediate and sustained airway hyperreactivity. Importantly, the researchers found that animals given an anti-C5 blocking antibody -- either systemically or when inhaled through a nebulizer (a common asthma inhalation device) -- showed substantial reductions in airway reactivity even in the face of ‘airway challenges’ with methacholine, a drug administered to confirm an asthma diagnosis.

The study, “Role of C5 in the Development of Airway Inflammation, Airway Hyperresponsiveness and Ongoing Airway Response,” resulted from collaborative research conducted in the laboratories of Jack Elias, M.D., Department of Internal Medicine, Yale University School of Medicine; Gregory Stahl, M.D., Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital; and Yi Wang, M.D., Senior Director of Preclinical Sciences at Alexion Pharmaceuticals, Inc.

“From my experience, I believe that these researchers have identified an extremely exciting and highly relevant new target for the treatment of asthma,” stated Dr. Stephen T. Holgate, Professor, Respiratory, Cell and Molecular Biology, University of Southampton School of Medicine, United Kingdom. “Importantly, this comprehensive body of research further demonstrated the potential utility of a nebulized form of the anti-C5 mAb for the treatment of the more chronic, indolent forms of asthma where edema and the ongoing release of inflammatory mediators from neutrophils and eosinophils are occurring. This form of asthma has historically been highly resistant to effective treatment with currently available therapies.”

The findings also demonstrate that C5 blockade provides more comprehensive and significant reductions in both airway hyperreactivity and pulmonary inflammation than does blockade of a related target, C5a alone. The anti-C5 blocking antibody, unlike other existing asthma therapies -- high-dose inhaled and oral corticosteroids -- blocked a wide range of inflammatory mediators known to contribute to the severity and persistence of asthma, including white blood cells and inflammatory mediators from eosinophils and neutrophils. This data suggests a direct role for complement-mediated inflammation in the pathogenesis of severe asthma.

“These findings, together with human clinical data showing complement activation in asthmatic patients, strongly suggest that complement activation is likely to be very important in the development of inflammation in allergic asthma. Since this is a new area of exploration in asthma, anti-C5 therapy may have the advantage of providing a novel class of therapeutics for the treatment of this severe disease,” said William W. Busse, M.D., the Charles E. Reed Professor of Medicine and the Head of Allergy and Clinical Immunology at the University of Wisconsin-Madison Medical School.

Alexion is engaged in the discovery and development of therapeutic products aimed at treating patients with a wide array of severe disease states, including hematologic and cardiovascular disorders, autoimmune diseases and cancer. Alexion’s two lead product candidates, pexelizumab and eculizumab, are currently undergoing evaluation in several clinical development programs, including two Phase III trials of eculizumab for the treatment of paroxysmal nocturnal hemoglobinuria (PNH), a Phase III trial of pexelizumab in coronary artery bypass graft (CABG) surgery patients undergoing cardiopulmonary bypass (CPB), and a Phase III trial of pexelizumab in acute myocardial infarction (AMI) patients. The pexelizumab trials are conducted in collaboration with Procter and Gamble Pharmaceuticals. Under the Special Protocol Assessment process, the FDA has agreed to the design of protocols for the Phase III pexelizumab trials that could, if successful, serve as the primary basis of review for approval of licensing applications for the two indications. Also under the Special Protocol Assessment process, the FDA has agreed to the design of protocols for the two trials of eculizumab in PNH patients that could, if successful, serve as the primary basis of review for approval of a licensing application for eculizumab in the PNH indication. Eculizumab is also being studied in rheumatoid arthritis and membranous nephritis. Alexion is engaged in discovering and developing a pipeline of additional antibody therapeutics targeting severe unmet medical needs, through its wholly owned subsidiary, Alexion Antibody Technologies, Inc. This press release and further information about Alexion Pharmaceuticals, Inc. can be found on the World Wide Web at: http://www.alexionpharm.com/.

This news release contains forward-looking statements. Such statements are subject to factors that may cause Alexion’s results and plans to differ from those expected, including the results of pre-clinical or clinical studies (including termination or delay in clinical programs), the need for additional research and testing, delays in arranging satisfactory manufacturing capability, inability to acquire funding on timely and satisfactory terms, delays in developing or adverse changes in commercial relationships, the possibility that results of earlier clinical trials are not predictive of safety and efficacy results in later clinical trials, dependence on Procter & Gamble Pharmaceuticals for development and commercialization of pexelizumab, the risk that third parties won’t agree to license any necessary intellectual property to us on reasonable terms, and a variety of other 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 for the year ended July 31, 2004 and in our other filings with the Securities and Exchange Commission. P&GP retains the development rights and the termination rights discussed in Alexion’s Form 10-K referred to above. Alexion does not intend to update any of these forward- looking statements to reflect events or circumstances after the date hereof, except when a duty arises under law.

Contacts: Alexion Pharmaceuticals, Inc. Leonard Bell, M.D. Chief Executive Officer (203) 272-2596 Rx Communications Patricia Garrison (Scientific Media) (917) 322-2567 Rhonda Chiger (Investors) (917) 322-2569 Noonan/Russo Emily Poe (Business and Financial Media) (212) 845-4266

Alexion Pharmaceuticals, Inc.

CONTACT: Leonard Bell, M.D., Chief Executive Officer of AlexionPharmaceuticals, Inc., +1-203-272-2596; or Patricia Garrison, ScientificMedia, +1-917-322-2567, or Rhonda Chiger, Investors, +1-917-322-2569, both ofRx Communications; or Emily Poe, Business and Financial Media of Noonan Russo,+1-212-845-4266, all for Alexion Pharmaceuticals, Inc.

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