Long-term follow-up of patients with neuromyelitis optica after repeated therapy with rituximab

Background: Neuromyelitis optica (NMO) is a severe autoimmune disease targeting optic nerves and spinal cord. The monoclonal anti-CD20 B-cell antibody rituximab is an emerging therapeutic option in NMO. However, neither long-term efficacy or safety of rituximab, nor the correlation between B-cell counts, B-cell fostering cytokines, aquaporin-4 antibodies (AQP4-ab), and disease activity in NMO, have been investigated prospectively.

Methods: We performed a prospective long-term cohort study of 10 patients with NMO who were treated up to 5 times with rituximab as a second-line therapy. Clinical examinations, B-cell counts, and serum concentrations of BAFF (B-cell activating factor of the TNF family; also called TNFSF13b), APRIL (a proliferation-inducing ligand; also called TNFSF13), AQP4-ab, and immunoglobulin levels were measured every 3 months.

Results: Repeated treatment with rituximab led to sustained clinical stabilization in most patients with NMO. Disease activity correlated with B-cell depletion, but not clearly with AQP4-ab or levels of APRIL. BAFF levels increased after application of rituximab and indicated persisting efficacy of the drug but did not correlate with disease activity. Overall, rituximab was well-tolerated even after up to 5 consecutive treatment courses; however, we observed several severe adverse reactions.

Conclusion: Our data indicate that long-term therapy with rituximab is effective in NMO as a second-line therapy and has an acceptable safety profile. Retreatment with rituximab should be applied before reappearance of circulating B cells.

Classification of evidence: This study provides Class IV evidence that repeated doses of rituximab result in stabilization in most patients.