The goal of this clinical trial is to study the efficacy and safety of BCD-132 (divozilimab) in subjects with neuromyelitis optica spectrum disorders (NMOSD).

BCD-132-6/AQUARELLE is an open-label phase 3 clinical study in subjects with NMOSD. Approximately 105 subjects will be enrolled.

The study consists of a screening period, a treatment period and a follow-up period. During treatment period, the subjects will receive the investigational product divozilimab.

The duration of participation for each subject will be approximately 104 weeks.

Inclusion Criteria:

• NMOSD diagnosed based on the 2015 NMOSD International Consensus Diagnostic Criteria
• Documented evidence of at least 1 relapse within 12 months before signing the informed consent form, or 2 relapses within 24 months before signing the informed consent form
• A total EDSS score of ≤ 7
• Presence of IgG antibodies to the Varicella Zoster virus at screening
• A CD19+ cell proportion of ≥ 1 % of the total lymphocyte count in patients exposed to other anti-B-cell therapies more than 6 months before signing the informed consent form

Exclusion Criteria:

• A relapse occurring less than 30 days before signing the informed consent form or at screening (patients may be re-screened)
• Intrathecal oligoclonal or monoclonal IgG production (in patients who are anti-AQP4 seronegative)
• Other nervous system disorders (including multiple sclerosis) that can mask or affect the assessment of NMOSD symptoms
• History of other autoimmune diseases requiring immunosuppressive therapy
• Prior exposure to: alemtuzumab, total lymphatic irradiation, bone marrow transplantation; anti-B-cell therapy drugs, abatacept, satralizumab within 6 months prior to signing the informed consent form; mitoxantrone, cyclophosphamide, methotrexate, cyclosporine A, tacrolimus, eculizumab, tocilizumab, natalizumab, interferon beta, glatiramer acetate, fingolimod, teriflunomide, dimethyl fumarate within 3 months before signing the informed consent form; immunoglobulin products within 30 days before signing the informed consent form; transfusion of blood or blood components within 30 days before signing the informed consent form; systemic corticosteroids at the time of signing the informed consent form