Efficacy, Safety, PK, PD, and ADA of Eculizumab in Chinese Adults With NMOSD

Inclusion Criteria:

• Participants with diagnosis of NMOSD as defined by the 2015 international consensusdiagnostic criteria

• Anti-AQP4 antibody positive

• At least 1 attack or relapse in the last 12 months prior to the Screening Period

• EDSS score ≤ 7

• If a participant enters the study receiving IST(s) for relapse prevention, theparticipant must be on a stable maintenance dose of IST(s) as follows, prior toscreening and must remain on that dose for the duration of the study, unless theparticipant experiences a relapse

• Female participants of childbearing potential must have a negative pregnancy test (serum HCG at screening

• Male participants are eligible to participate if they agree to the following duringthe study intervention Treatment Period and for at least 5 months after the lastdose of study intervention:

• Refrain from donating fresh unwashed semen. PLUS, either,

• Be abstinent from heterosexual intercourse as their preferred and usuallifestyle (abstinent on a long term and persistent basis) and agree to remainabstinent. OR

• Must agree to use barrier as detailed below:

• Agree to use a male condom when having sexual intercourse with a WOCBP whois not currently pregnant.

Exclusion Criteria:

• Pregnant, breastfeeding, or intending to conceive during the course of the study

• Prior history of N meningitidis infection or unresolved meningococcal disease

• Any systemic bacterial or other infection which is clinically significant in theopinion of the Investigator and has not been treated with appropriate antibiotics

• Presence of fever ≥ 38 C within 7 days prior to study intervention administration onDay 1

• Hypersensitivity to murine proteins or to one of the excipients of studyintervention

• Use of rituximab, inebilizumab, or other B cell-depleting therapy within 6 monthsprior to Day 1 and during the study

• Use of mitoxantrone or satralizumab within 3 months prior to screening and duringthe study

• Use of IVIg within 3 weeks prior to screening

• If a participant enters the study receiving oral corticosteroid(s) with or withoutother ISTs, the daily corticosteroid dose must be no more than prednisone 20 mg/day (or equivalent) prior to screening and the participant must remain on that dose forthe duration of the study or until the participant experiences a relapse (specificmedications listed in Section 6.9.1 may be allowed)

• Has previously received treatment with C5 inhibitors

• Participation in any other investigational drug study or exposure to aninvestigational drug or device within 5 half-lives of treatment (if known) or 30days, which is longer, before the first dose administration