Inclusion Criteria:  Male or female, aged ≥ 18 years old Body weight ≥ 40 kg Documented diagnosis of PNH No complement inhibitor therapy for ≥ 12 months prior to screening Documentation of current vaccinations against Neisseria meningitidis and Streptococcus pneumoniae or willingness to start vaccination series At screening: PNH clone of ≥ 10%, hemoglobin ≤ 10.5 g/dL and lactate dehydrogenase ≥ 2 × upper limit of normal  Exclusion Criteria:  Known history of or existing diagnosis of hereditary complement deficiency History of hematopoietic cell transplant or solid organ transplant or anticipated candidate for transplantation Myocardial infarction or cerebrovascular accident within 30 days prior to screening, or current and uncontrolled clinically significant cardiovascular or cerebrovascular condition History of malignancy within 5 years prior to the screening visit Active bacterial, viral, or fungal infection or any other serious infection within 14 days prior to screening Treatment with anti-thymocyte globulin within 180 days prior to screening Initiation of treatment with an erythrocyte or platelet growth factor, or danazol within 28 days prior to screening Receiving iron supplementation with an unstable dose in the 28 days prior to screening