Alexion Pharmaceuticals, Inc. (Nasdaq: ALXN) today announced that Soliris ® (eculizumab), the company’s first-in-class terminal complement inhibitor, has been granted an orphan drug designation by the U.S. Food and Drug Administration (FDA) for the treatment of neuromyelitis optica (NMO), a life-threatening, ultra-rare neurological disorder. In a Phase 2 study presented at the 2012 annual meeting of the American Neurological Association (ANA), Soliris treatment was associated with a significant reduction in the frequency of relapses (recurring attacks) in patients with severe, relapsing NMO. 1 Soliris is not approved for the treatment of patients with NMO. The FDA, through its Office of Orphan Products Development (OOPD), grants orphan status to drugs and biologic products that are intended for the safe and effective treatment, diagnosis, or prevention of rare diseases or disorders that affect fewer than 200,000 people in the U.S. Orphan drug designation provides a drug developer with certain benefits and incentives, including a period of marketing exclusivity if regulatory approval is ultimately received for the designated indication. “There are no approved therapies for patients with NMO, an extremely rare and debilitating disease that can lead to paralysis, blindness and death,” said Martin Mackay, Ph.D., executive vice president and global head of R&D at Alexion. “This orphan drug designation is a positive step toward understanding and meeting the needs of this underserved patient population. In clinical trials to date, terminal complement inhibition with Soliris appeared to significantly reduce the attack rate in patients with severe, refractory relapsing NMO.” 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. 2-4 The disease leads to severe weakness, paralysis, respiratory failure, loss of bowel and bladder function, blindness and premature death. 5-7 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. 6,8,9 Fifty percent of relapsing NMO patients have been reported to sustain permanent severe disability, including paralysis and blindness, within five years of disease onset. 10 Most NMO-related deaths result from respiratory complications from NMO attacks. 10,11 The disease primarily affects women, with a female to male ratio as high as a 9:1. 12 Phase 2 Data in Patients with NMO The Phase 2 study reported at the ANA 2012 annual meeting and subsequently published in The Lancet Neurology 13 was a single-arm, open-label, investigator-initiated trial in 14 women with severe, relapsing NMO who were treated for one year. The study met its primary efficacy endpoint, reduction in annualized relapse rate, with high degrees of clinical and statistical significance: a decline in the median annualized attack rate from 3.0 attacks per year pre-Soliris treatment to 0 attacks per year during 12 months of chronic Soliris treatment (p<0.0001). After 12 months of treatment, 86% (12 of 14) of these severely affected patients were completely attack-free. 1 Additionally, Soliris was associated with significant improvements in key secondary endpoints. The median expanded disability status scale (EDSS) score improved from 4.3 pre-treatment to 3.5 after 12 months of treatment with Soliris (p<0.01). Importantly, all patients experienced either improvement or stability in all key outcome measures, including EDSS, ambulatory function as measured by the Hauser Ambulation Index, and visual function as measured by visual acuity. Soliris was generally well-tolerated, with the three most common adverse events being headache, nausea, and dizziness. One case of meningococcal sepsis occurred. The patient made an uneventful recovery and restarted treatment with eculizumab to complete the study. 1 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 U.S., E.U., 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 also approved in the U.S., E.U., and other countries as the first and only treatment for patients with atypical hemolytic uremic syndrome (aHUS), a genetic, life-threatening, ultra-rare disease characterized by complement-mediated thrombotic microangiopathy (TMA, the formation of blood clots in small vessels).