Alexion?s Soliris® (eculizumab) Receives Positive Opinion from the Committee for Orphan Medicinal Products forTreatment of Neuromyelitis Optica (NMO)

Alexion Pharmaceuticals, Inc. (Nasdaq: ALXN) today announced that Soliris® (eculizumab), the company’s first-in-class terminal complement inhibitor, has received a positive opinion for orphan medicinal product designation from the Committee for Orphan Medicinal Products (COMP) of the European Medicines Agency (EMA) for the treatment of neuromyelitis optica (NMO), a life-threatening, ultra-rare neurological disorder. The positive opinion of the COMP has now been forwarded to the European Commission for final approval and publication in the community register. Soliris is not approved in any country for the treatment of patients with NMO.

“We are pleased that the COMP has provided a positive opinion regarding orphan medicinal product status for Soliris for the treatment of patients with NMO, particularly after having been recently granted orphan-drug designation by the FDA,” said Martin Mackay, Ph.D., Executive Vice President and Global Head of R&D at Alexion. “NMO is an extremely rare, chronic and debilitating disease that can lead to paralysis, blindness and death, and there are no approved therapies for it. Therefore, this news represents another positive step toward meeting the needs of this underserved patient population in the EU.”

The European Commission grants orphan medicinal product status to provide incentives to develop medicinal products to treat, prevent or diagnose diseases or conditions that affect no more than five in 10,000 persons in the EU. The orphan medicinal product status designation would provide Alexion with certain benefits and incentives, including a period of marketing exclusivity.

About NMO

In patients with NMO, uncontrolled complement activation causes destruction of myelin-producing cells, leading to severe damage to the central nervous system (CNS), including the spinal cord and optic nerve.1-3 The disease leads to severe weakness, paralysis, respiratory failure, loss of bowel and bladder function, blindness and premature death.4-6 Patients with NMO have a life-long exposure to the uncontrolled complement activation due to chronic autoimmune attack, and most patients experience an unpredictable, relapsing course of disease with cumulative disability, as each attack adds to the neurologic disability.5,7,8 Fifty percent of relapsing NMO patients have been reported to sustain permanent severe disability, including paralysis and blindness, within five years of disease onset.9 Most NMO-related deaths result from respiratory complications from NMO attacks.9,10 The disease primarily affects women, with a female to male ratio as high as a 9:1.11

About Soliris

Soliris is a first-in-class terminal complement inhibitor developed from the laboratory through regulatory approval and commercialization by Alexion. Soliris is approved in the United States, European Union (EU) and other countries as the first and only treatment for aHUS patients. Soliris is indicated to inhibit complement-mediated TMA. Soliris is not indicated for the treatment of patients with Shiga toxin E. coli-related hemolytic uremic syndrome (STEC-HUS). Alexion is evaluating the safety and efficacy of Soliris for the treatment of patients with STEC-HUS.

Soliris also is approved in the US, EU, Japan and other countries as the first and only treatment for patients with paroxysmal nocturnal hemoglobinuria (PNH), a debilitating, ultra-rare and life-threatening blood disorder characterized by complement-mediated hemolysis (destruction of red blood cells). Soliris is indicated to reduce hemolysis.

Alexion´s breakthrough approach in terminal complement inhibition has received the pharmaceutical industry´s highest honors: the 2008 Prix Galien USA Award for Best Biotechnology Product with broad implications for future biomedical research, and the 2009 Prix Galien France Award in the category of Drugs for Rare Diseases.

More information, including the full prescribing information on Soliris, is available at www.soliris.net.

Important Safety Information

The Summary of Product Characteristics (SmPC) for Soliris includes a special warning and precaution for use: Due to its mechanism of action, the use of Soliris increases the patient’s susceptibility to meningococcal infection (Neisseria meningitidis). These patients might be at risk of disease by uncommon serogroups (particularly Y, W135 and X), although meningococcal disease due to any serogroup may occur. To reduce the risk of infection, all patients must be vaccinated at least 2 weeks prior to receiving Soliris. PNH patients must be vaccinated 2 weeks prior to Soliris initiation. aHUS patients who are treated with Soliris less than 2 weeks after receiving a meningococcal vaccine must receive treatment with appropriate prophylactic antibiotics until 2 weeks after vaccination. Patients must be re-vaccinated according to current medical guidelines for vaccination use. Tetravalent vaccines against serotypes A, C, Y and W135 are strongly recommended, preferably conjugated ones.

Vaccination may not be sufficient to prevent meningococcal infection. Consideration should be given to official guidance on the appropriate use of antibacterial agents. Cases of serious or fatal meningococcal infections have been reported in Soliris-treated patients. All patients should be monitored for early signs of meningococcal infection, evaluated immediately if infection is suspected, and treated with appropriate antibiotics if necessary. Patients should be informed of these signs and symptoms and steps taken to seek medical care immediately. Physicians must discuss the benefits and risks of Soliris therapy with patients and provide them with a patient information brochure and a patient safety card. The most common or serious adverse reactions were headache (occurred mostly in the initial phase), leukopenia and meningococcal infection. Soliris is not expected to affect the aplastic component of anaemia in patients with PNH.

Please see Summary of Product Characteristics for full prescribing information for Soliris, including all special warnings and precautions.

About Alexion

Alexion Pharmaceuticals, Inc. is a biopharmaceutical company focused on serving patients with severe and ultra-rare disorders through the innovation, development and commercialization of life-transforming therapeutic products. Alexion is the global leader in complement inhibition and has developed and markets a treatment for patients with PNH and aHUS, two debilitating, ultra-rare and life-threatening disorders caused by chronic uncontrolled complement activation. The treatment is currently approved in more than 40 countries for the treatment of PNH, and in the United States and the European Union for the treatment of aHUS. Alexion is evaluating other potential indications for its marketed drug and is developing four other highly innovative biotechnology product candidates, which are being investigated across nine severe and ultra-rare disorders beyond PNH and aHUS.

Safe Harbor Statement

This news release contains forward-looking statements, including statements related to anticipated clinical development, regulatory and commercial milestones and potential health and medical benefits of Soliris® (eculizumab) for the potential treatment of patients with PNH and aHUS. Forward-looking statements are subject to factors that may cause Alexion´s results and plans to differ from those expected, including for example, decisions of regulatory authorities regarding marketing approval or material limitations on the marketing of Soliris for its current or potential new indications, 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, 2013. 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

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8 Kuroda H, Fujihara K, Takano R, et al. Increase of complement fragment C5a in cerebrospinal fluid during exacerbation of neuromyelitis optica. J Neuroimmunol 2013;254(1-2):178-82.

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10 Kitley J, Leite MI, Nakashima I, et al. Prognostic factors and disease course in aquaporin-4 antibody-positive patients with neuromyelitis optica spectrum disorder from the United Kingdom and Japan. Brain 2012;135(Pt 6):1834-49.

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