Patients with a rare blood disorder called PNH experienced a 92 per cent reduction in the incidence of life-threatening blood clots (thromboses) following treatment with Soliris (eculizumab), according to an analysis of clinical studies recently published online in Blood, the journal of the American Society of Haematology.

Soliris, developed by Alexion Pharmaceuticals, Inc., is the first therapy approved for paroxysmal nocturnal haemoglobinuria (PNH), a rare, debilitating and life-threatening blood disorder defined by the destruction of red blood cells, or haemolysis. In patients with PNH, haemolysis can cause severe anaemia, disabling fatigue, recurrent pain, shortness of breath, pulmonary hypertension, intermittent episodes of dark coloured urine (haemoglobinuria), kidney disease, impaired quality of life and thromboses.

"Thrombosis is the leading cause of premature death in PNH patients and the most feared complication of PNH," said Dr. Peter Hillmen, senior author of the paper and Consultant Haematologist of the General Infirmary at Leeds, Leeds, UK. "In several clinical trials, Soliris reduced haemolysis in all PNH patients and significantly improved anaemia, fatigue and quality of life. The comprehensive analyses demonstrate that Soliris substantially reduced the risk of thrombosis in a diverse population of PNH patients, including those who might be expected to have less severe disease."

Approximately 40 percent of patients with PNH experience thrombosis during the course of the disease.3,4,5,6 An initial thrombosis increases the relative risk of death by five- to ten-fold for PNH patients.3,7 Thrombosis is related to haemolysis in patients with PNH, and patients with both smaller and larger PNH clones are reported to experience this complication. Research involving a small group of PNH patients, including those without a history of blood transfusion, found that 60 percent had sub-clinical thrombosis, which could later develop into blood clots.

"For decades, people with PNH have lived with debilitating symptoms, including the threat of blood clots and their complications," said Leonard Bell, MD, Chief Executive Officer of Alexion. "This publication reinforces the importance of our goal to ensure that every PNH patient who can benefit from Soliris will have access to it."

"Many PNH patients face not only devastating symptoms, but a sharply increased risk for developing life-threatening blood clots as a result of their disease," said John Huber, Executive Director of the Aplastic Anaemia & MDS International Foundation. "This news provides additional hope for patients struggling with PNH and the danger of PNH-related blood clots. We look forward to seeing the impact this new analysis has on treatment of patients with PNH."

The publication, titled "Effect of the complement inhibitor eculizumab on thromboembolism in patients with paroxysmal nocturnal hemoglobinuria," analyzed data from 195 patients studied in the Soliris Phase II and Phase III trials, including the Triumph and Shepherd studies. Patients were enrolled in the United States, Europe, Australia and Canada and treated with Soliris for up to 54 months. Soliris reduced haemolysis in all treated patients and reduced thrombosis by 92 per cent, with three events during Soliris treatment compared to 39 events during the same period of time prior to treatment (P<0.0001). The collection of thrombotic events was defined prospectively by clinical trial protocols. The article is available online at http://bloodjournal.hematologylibrary.org/cgi/content/abstract/blood-2007-06-095646v1. The analysis will also be published in a future print edition of Blood.

PNH is an acquired genetic blood disorder defined by haemolysis, in which patients' red blood cells are destroyed by complement, a component of the body's immune system. PNH is a rare disease that affects an estimated 8,000 to 10,000 people in North America and Europe. PNH often strikes people in the prime of their lives, with an average age of onset in the early 30's. Approximately ten percent of all patients first develop symptoms at 21 years of age or younger. PNH develops without warning and can occur in men and women of all races, backgrounds and ages. PNH often goes unrecognized, with delays in diagnosis often ranging from one to more than 10 years. The estimated median survival for PNH patients is between 10 and 15 years from the time of diagnosis.

PNH has been identified more commonly among patients with disorders of the bone marrow, including aplastic anemia (AA) and myelodysplastic syndrome (MDS). In patients with thrombosis of unknown origin, PNH may be an underlying cause.

Soliris was approved in March 2007 by the US Food and Drug Administration (FDA) as the first treatment for PNH, a rare, debilitating and life-threatening blood disorder defined by haemolysis, or the destruction of red blood cells. In June 2007, the European Commission (EC) also approved the use of Soliris (eculizumab) for the treatment of patients with PNH. Soliris is the first therapy approved in Europe for the treatment of PNH and was the first medicinal product to receive EU approval under the EMEA Accelerated Assessment Procedure.