Efficacy and Safety Study of Ravulizumab IV in Pediatric Participants With NMOSD

Inclusion Criteria:

• Participants must be anti-AQP4 Ab-positive and have a diagnosis of NMOSD as definedby the 2015 international consensus diagnostic criteria.

• Complement inhibitor treatment-naïve participants must have had at least 1 attack orrelapse in the last 12 months prior to the Screening Period.

• Expanded Disability Status Scale (EDSS) score ≤ 7.

• Eculizumab-experienced participants must be clinically stable per Investigator for 30 days and have been treated with eculizumab in Study ECU-NMO-303 for at least 90days prior to screening with no missed doses within 2 months prior to Day 1.

• Participants who enter the study receiving supportive IST(s) (eg, corticosteroid,azathioprine [AZA], mycophenolate mofetil [MMF], methotrexate [MTX], tacrolimus [TAC], cyclosporin [CsA], or cyclophosphamide [CYC]) for the prevention of relapse,either in combination or monotherapy, must be on a stable dosing regimen of adequateduration prior to Screening and remain on a stable dosing regimen during theScreening Period.

• To reduce the risk of meningococcal infection (Neisseria meningitidis), allparticipants must be vaccinated against meningococcal infection.

• Documented vaccination for Hib and S pneumoniae at least 14 days prior to Day 1according to national/local guidelines for the applicable age group.

Exclusion Criteria:

• Use of rituximab within 3 months prior to screening.

• Currently treated with a biologic medications (other than eculizumab) that mayaffect immune system functioning, or has stopped treatment with a biologicmedication that may affect immune system functioning, and 5 half lives of themedication have not elapsed by the time of the Screening Visit.

• Use of intravenous immunoglobulin (IVIg) or plasma exchange (PE) within 3 weeksprior to Screening.

• Participation in another investigational drug or investigational device study (otherthan Study ECU-NMO-303) within 5 half lives of that investigational product (ifknown) or 30 days before initiation of the first dose of study drug, whichever islonger.

• Use of immunomodulatory therapies for multiple sclerosis within 3 months prior toScreening.