Eculizumab in Treating Patients With Paroxysmal Nocturnal Hemoglobinuria

DISEASE CHARACTERISTICS: Diagnosis of paroxysmal nocturnal hemoglobinuria Must have required ≥ 4 episodes of transfusions for anemia or anemia-related symptoms within the past year Mean pre-transfusion hemoglobin ≤ 10. 5 g/dL over the past year Glycosylphosphatidylinositol (GPI)-deficient red blood cell clone (type III cells) of ≥ 10% by flow cytometry Must have received 1 packed red blood cell transfusion during the study observation period (within 48 hours of the hemoglobin level that precipitated the transfusion) and within 1.5 g/dL of the mean pre-transfusion hemoglobin level over the past year Pre-transfusion hemoglobin ≤ 9 g/dL with symptoms Pre-transfusion hemoglobin ≤ 7 g/dL without symptoms Received Neisseria meningitidis vaccination at least 2 weeks before initiation of study therapy PATIENT CHARACTERISTICS: Age 18 and over Performance status Not specified Life expectancy Not specified Hematopoietic See Disease Characteristics Absolute neutrophil count > 500/mm^3 Platelet count ≥ 100,000/mm^3 Hepatic Lactate dehydrogenase ≥ 1.5 times upper limit of normal Renal Not specified Immunologic No known or suspected active bacterial infection No recurrent bacterial infections No history of meningococcal disease Other No known or suspected hereditary complement deficiency No other condition that would increase the patient's risk or confound the outcome of the study Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy See Disease Characteristics No prior bone marrow transplantation Concurrent epoetin alfa allowed* Chemotherapy Not specified Endocrine therapy Concurrent corticosteroids allowed** Radiotherapy Not specified Surgery Not specified Other More than 30 days since prior participation in another investigational drug trial More than 30 days since prior investigational agents, devices, or procedures Concurrent immunosuppressants allowed* Concurrent warfarin allowed provided INR level is stable for the past 4 weeks and expected to remain stable during observation and study treatment Concurrent iron supplements or folic acid allowed** Concurrent low-molecular weight heparin allowed** NOTE: *Provided dose is stable for the past 26 weeks and during study observation and treatment NOTE: **Provided dose is stable for the past 4 weeks and expected to remain stable (or decrease for corticosteroids) during study observation and treatment