Treatments
During the RCP, patients were randomized 1:1 to intravenous ravulizumab or matching placebo. Ravulizumab dosing during the study was based on patients’ body weight. In the RCP, patients received an initial loading dose of 2400, 2700, or 3000 mg on Day 1, followed by a maintenance dose of 3000, 3300, or 3600 mg starting on Day 15 and every 8 weeks thereafter. On completing the RCP, patients were invited to enter the OLE, which started for each patient when he or she received a dose of ravulizumab at Week 26 of the study. The doses and dosing schedule at the start of the OLE were designed to ensure that patients and study personnel remained blinded to the treatment assignment in the RCP. Therefore, at Week 26, patients who had received ravulizumab during the RCP (ravulizumab–ravulizumab group) received ravulizumab 900 mg, and patients who had received placebo (placebo–ravulizumab group) received a body-weight-based loading dose of 2400, 2700, or 3000 mg. For the next scheduled maintenance dose at Week 28 and every 8 weeks thereafter for up to 4 years, all patients received body-weight-based doses of 3000, 3300, or 3600 mg.Patients receiving stable therapy with cholinesterase inhibitors and immunosuppressants at the start of the study could continue them. Dose changes were not permitted during the RCP, but were allowed during the OLE at the investigator’s discretion. Rescue therapy, including high-dose corticosteroids, plasma exchange, or intravenous immunoglobulin, was permitted throughout the study for patients experiencing clinical deterioration.