CHESHIRE, Conn.--(BUSINESS WIRE)--Paroxysmal nocturnal hemoglobinuria (PNH) cells are present in the majority of patients with myelodysplastic syndromes (MDS), aplastic anemia (AA), and other bone marrow failure syndromes (BMF), according to interim results from 5,285 patients enrolled in the EXPLORE trial. EXPLORE (EXamination of PNH, by Level Of CD59 on REd and white blood cells) is the first large multicenter study to determine the frequency of PNH cells in these patient populations using a central laboratory conducting a high sensitivity test for PNH cells. The findings from EXPLORE will be presented tomorrow at the 45th Annual Meeting of the American Society of Clinical Oncology (ASCO). The EXPLORE trial was sponsored by Alexion Pharmaceuticals, Inc. (Nasdaq:ALXN).