PREVENT

Treatment tested

• Eculizumab

  Complement C5 inhibitor

Placebo or sham

• Placebo

Other measures (6)

Key Inclusion Criteria: 1. Male or female participants ≥ 18 years old. 2. Diagnosis of NMO or NMOSD. 3. AQP4 antibody seropositive. 4. Historical relapse of at least 2 relapses in the last 12 months or 3 relapses in the last 24 months with at least 1 relapse in the 12 months prior to the screening. 5. Expanded Disability Status Scale score ≤ 7. 6. If a participant entered the study receiving immunosuppressive therapy (IST) for relapse prevention, the participant must have been on a stable maintenance dose of IST(s), as defined by the treating physician, prior to Screening and must have remained on that dose for the duration of the study, unless the participant experienced a relapse. 7. Female participants of childbearing potential were to have a negative pregnancy test (serum human chorionic gonadotropin). Participants were required to practice an effective, reliable, and medically approved contraceptive regimen during the study and for up to 5 months following discontinuation of treatment. Key Exclusion Criteria: 1. Use of rituximab within 3 months prior to Screening. 2. Use of mitoxantrone within 3 months prior to Screening. 3. Use of intravenous immunoglobulin within 3 weeks prior to Screening.

The objectives of this time-to-event study were to assess the efficacy and safety of eculizumab as compared with placebo in participants with neuromyelitis optica spectrum disorder (NMOSD) who were anti-aquaporin-4 (AQP4) antibody-positive.