Press Releases
August 7, 2008

Alexion Secures U.S. Patent for ALXN6000, a First-In-Class Anti-CD200 Monoclonal Antibody

CHESHIRE, Conn., Aug 07, 2008 /PRNewswire-FirstCall via COMTEX News Network/ -- Alexion Pharmaceuticals, Inc. (Nasdaq: ALXN) today announced that the U.S. Patent and Trademark Office has issued Patent Number 7,408,041 titled, "Polypeptides and Antibodies Derived from Chronic Lymphocytic Leukemia Cells and Uses Thereof." The patent is assigned to Alexion and includes claims that encompass the composition-of-matter of Alexion's anti-CD200 humanized monoclonal antibody, which is known by its working name, ALXN6000.

"Alexion continues to be focused on developing first-in-class therapeutics for patients who have severe and life-threatening medical conditions, and few, if any, treatment options," said Leonard Bell, M.D., Chief Executive Officer of Alexion. "We are committed to fully investigate the therapeutic potential of ALXN6000 as a drug therapy for patients with B-cell chronic lymphocytic leukemia and other hematologic and solid-tumor cancers."

The U.S. Food and Drug Administration ("FDA") recently authorized Alexion's Investigational New Drug application ("IND") for a clinical trial of ALXN6000 as a treatment for patients with refractory or relapsing B-cell Chronic Lymphocytic Leukemia ("CLL"). As previously announced, dosing in an open-label Phase I/II trial has commenced. Recruitment and dosing of patients in the trial is expected to continue through 2009. More information is available at the www.clinicaltrials.gov website maintained by the U.S. National Institutes of Health.

About ALXN6000

The CD200 molecule is overexpressed in certain tumor cells and may inhibit the body's immune response to that tumor which could allow for the growth and survival of tumors involved in several types of cancers, including CLL, multiple myeloma, non-Hodgkins lymphoma, melanoma, ovarian cancer and neuroblastoma. Laboratory data have shown that ALXN6000 blocks binding of CD200 to the CD200 receptor, which has been shown to enhance the immune response to tumors and reduce tumor growth. The anti-tumor activity of ALXN6000 was reported in the January 2008 issue of the Journal of Immunology. (1)

About CLL

CLL is the second most common type of leukemia in adults. (2) The American Cancer Society estimates that, in 2008, there will be approximately 15,000 new cases of CLL in the United States. Approximately 4,000 people in this country are expected to die of CLL during 2008. (3) CLL, which involves production of abnormal lymphocytes (white blood cells) starts in the bone marrow and can spread through the blood to the lymph nodes, spleen, liver and other parts of the body. (3) B-cell CLL is characterized by clonal expansion of abnormal B lymphocytes. Patients with CLL also may develop enlargement of the spleen and lymph nodes, and pancytopenia (depletion of red and white blood cells and platelets), ultimately resulting in hemorrhage, infection and death. (4)

About Alexion

Alexion Pharmaceuticals, Inc. is a biopharmaceutical company working to develop and deliver life-changing drug therapies for patients with serious and life-threatening medical conditions. Alexion is engaged in the discovery, development and commercialization of therapeutic products aimed at treating patients with a wide array of severe disease states, including hematologic diseases, cancer, and autoimmune disorders. In March 2007, the FDA granted marketing approval for Alexion's first product, Soliris(R) (eculizumab), for all patients with paroxysmal nocturnal hemoglobinuria ("PNH"), a rare, debilitating and life-threatening blood disease. In June 2007, the European Commission granted marketing approval for Soliris in the European Union for all patients with PNH. Alexion is evaluating other potential indications for Soliris as well as other formulations of eculizumab for additional clinical indications, and is pursuing development of other antibody product candidates in early stages of development. This press release and further information about Alexion Pharmaceuticals, Inc. can be found at: www.alexionpharm.com.

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Safe Harbor Statement

This news release contains forward-looking statements, including statements related to the Company's study of its ALXN6000 antibody, potential health and medical benefits from ALXN6000 as a treatment for cancer, and the potential patient base for ALXN6000 as a treatment for CLL in the U.S. Forward-looking statements are subject to factors that may cause Alexion's results and plans to differ from those expected, including for example, the ultimate outcome of the current or subsequent clinical studies of ALXN6000, decisions of regulatory authorities regarding marketing approval or material limitations on the marketing of ALXN6000 as a treatment for CLL or any other condition, 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 Quarterly Report on Form 10-Q for the period ended March 31, 2007 and in our other filings with the Securities and Exchange Commission. 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.

References:

(1) Kretz-Rommel A, Qin F, Dakappagari N et al. J Immunol. 2008; 180 (2):699-705.

(2) National Cancer Institute. General Information About Chronic Lymphocytic Leukemia. http://www.cancer.gov/cancertopics/pdq/treatment/CLL/Patient/page1/print. Accessed on August 5, 2008.

(3) American Cancer Society. Overview: Leukemia - Chronic Lymphocytic (CLL). http://www.cancer.org/docroot/CRI/CRI_2_1x.asp?rnav=criov&dt=62. Accessed on August 4, 2008.

(4) Catovsky D. Definition and diagnosis of sporadic and familial chronic lymphocytic leukemia. Hematol Oncol Clin North Am. 2004; 18(4):783-94.

SOURCE Alexion Pharmaceuticals, Inc.

http://www.alexionpharm.com

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