A Longitudinal Study of ACTEMRA® (Tocilizumab) as Monotherapy in Highly Active NMOSD

Neuromyelitis Optica Spectrum Disorder (NMOSD) is a severe inflammatory disease of the central nervous system characterized by relapsing optic neuritis and longitudinal extensive transverse myelitis. The specific autoantibody against aquaporin 4 (AQP4-ab) has been suggested to contribute to the pathogenesis of the disease. Peripheral blood plasma cells are a major source of AQP4-ab. Previous studies have observed increased IL-6 levels in serum and cerebrospinal fluid of patients with NMOSD, particularly during relapses. Exogenous interleukin (IL)-6 promotes the survival of plasma cells and their production of AQP4-ab in vitro. And blockade of IL-6 receptor signaling by an anti-IL-6 receptor antibody reduces the survival of plasma cells in vitro. Tocilizumab (ACTEMRA®), a humanized monoclonal antibody against the IL-6 receptor, has shown beneficial clinical effects in some patients with NMOSD when concomitant immunosuppressive medications were administered. However, the long-lasting biological effects of preceding immunotherapies such as rituximab might overlap with the subsequent tocilizumab therapy. To reduce the side effects of concomitant treatments to large extent and verify the beneficial effects of tocilizumab, we evaluate the safety and efficacy of tocilizumab as monotherapy in patients with NMOSD.