To evaluate long-term outcomes of inebilizumab treatment in AQP4⁺ NMOSD participants from the N-MOmentum trial with a history of immunosuppressant therapy as compared to those without.

N-Momentum (NCT02200770) was a 28-week-randomized-phase-2/3 trial of inebilizumab vs placebo, with an optional Open-Label-Extension (OLE) (>2 years).  Immunosuppressant medication for the prevention or treatment of NMOSD relapses was allowed prior to dosing on Day 1. In this analysis, AQP4⁺ participants who received inebilizumab (through OLE) were grouped by no history of immunosuppression therapy beyond treatment of acute NMOSD attacks (naïve), or prior azathioprine (AZA) and/or mycophenolate mofetil (MMF) therapy. Outcomes included annualized relapse and hospitalization rates, as well as safety assessments.

Among inebilizumab participants, 94 received prior-AZA/MMF and 103 were immunosuppressant-naïve. The total patient-years of inebilizumab treatment in the prior-AZA/MMF group was 300.35 and for immunosuppressant-naïve participants, 335.7. The annualized relapse rate (95% confidence interval [CI]) for participants with prior-AZA/MMF was 0.11 (0.07, 0.17), compared to 0.08 (0.05, 0.14) for naïve. The annualized NMOSD-related inpatient hospitalization rate (annualized rate [95% CI]) for prior-AZA/MMF was 0.15 (0.08, 0.27), and 0.12 (0.06, 0.22) for naïve. The percentage of participants with ≥1 study drug-related-treatment-emergent-adverse-event (TEAE) was 30.9% (29/94) in prior-AZA/MMF and 46.6% (49/103) of naïve; 4.3% (4) of prior-AZA/MMF and 5.8% (6) of immunosuppressant-naïve reported ≥1 study drug-related-serious-adverse-event. Most adverse events were infection-related for both groups; (72.3% (68/94) for prior-AZA/MMF and 76.7% (79/94) for naïve).