A Study of MIL62 in Patients With Neuromyelitis Optica Spectrum Disorder (NMOSD)

Inclusion Criteria:

1. Patients who meet the diagnostic criteria for NMOSD established by the InternationalPanel for NMO Diagnosis (IPND) in 2015 and are seropositive for AQP4-IgG.

2. Male or female patients aged 18 to 70 years, inclusive of the endpoints..

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

4. Phase Ib: At least 1 attack of NMOSD requiring rescue treatment within 2 years priorto screening. Phase III: At least 1 attack of NMOSD requiring rescue treatmentwithin 1 year prior to screening; or at least 2 attacks of NMOSD requiring rescuetreatment within 2 years prior to screening, including the first attack.

5. Glucocorticoid treatment prior to screening is allowed, and within 14 days beforethe first administration, the dose should be ≤20 mg/day of prednisone or itsequivalent dose of glucocorticoids.

6. Patients who had an attack of the disease before screening must have stable orimproved attack symptoms for at least 4 weeks prior to the first administration.

7. Voluntarily sign the informed consent form.

Exclusion Criteria:

1. Subjects who have received Rituximab, Inebilizumab, Ozanimod, Telitacicept, or anyB-cell depleting drugs within 6 months prior to the screening period are allowed toenroll if their CD19 or CD20 positive B-cell counts are above the lower limit ofnormal; or if their CD4 positive T-lymphocyte counts are < 200 cells/μL.

2. Having used Tocilizumab, Satralizumab, Eculizumab, Efgartigimod, or other non-B-celldepleting biological agents with therapeutic effects on NMOSD, or mitoxantrone, oralkylating agents such as cyclophosphamide within 3 months prior to the firstadministration.

3. Phase Ib: Subjects who have used immunosuppressants such as azathioprine,mycophenolate mofetil, tacrolimus, cyclosporine, methotrexate, and cyclophosphamidebefore the first administration are eligible for enrollment, provided that theinterval since discontinuing the drugs exceeds 5 times their half-life. Phase III:Subjects who have used immunosuppressants other than glucocorticoids within 1 monthprior to the first administration, including but not limited to azathioprine,mycophenolate mofetil, tacrolimus, cyclosporine, and methotrexate, are excluded (exclusion is not required if the continuous use duration is ≤7 days).

4. Within 28 days prior to the first administration, plasma exchange (PE), moderateblood transfusion, or immunomodulatory drugs such as interferon β, interferon γ, orintravenous immunoglobulin (IVIG) have been used.

5. Live vaccines or attenuated vaccines were administered within 28 days prior to thefirst dose.