Clinical Study to Evaluate the Effects of the Complement C5 Inhibitor Ravulizumab on Serum Neurofilament Light Chain (sNfL) and Glial Fibrillary Acidic Protein (sGFAP) Levels in Patients With Aquaporin-4-Positive (AQP4-Ab+) Neuromyelitis Optica Spectrum Disorder (NMOSD)

Inclusion criteria

• . Patient must be 18 years of age or older, at the time of signing the informed consent.
• . Anti-AQP4 Ab-positive at screening and a diagnosis of NMOSD as defined by the 2015 international consensus diagnostic criteria (Wingerchuk, 2015). A historically positive anti-AQP4 Ab test may be acceptable if the test was performed using an acceptable, validated cell-based assay from an accredited laboratory.
• . At least 1 clinical attack prior to the Prescreening/Screening Periods.
• . Treatment-naïve patients or patients under specific off-label treatments (rituximab, corticosteroids, azathioprine, mycophenolate mofetil) or the complement C5 inhibitor ravulizumab. Naïve patients who initiate ravulizumab at enrolment, should have been prescribed ravulizumab, but not yet initiated treatment, according to the label and local market reimbursement criteria.
• . Vaccinated against N. meningitidis (for serogroups A, C, W, Y and B) a) within 3 years and at least 2 weeks prior to the first dose of ravulizumab, or b) at the time of the first dose of ravulizumab provided that antibacterial drug prophylaxis is administered as per National Vaccination Guidelines and Summary of Product Characteristics of ravulizumab.