Current and emerging biologics for the treatment of neuromyelitis optica spectrum disorders.

INTRODUCTION: Treatment options for patients suffering from neuromyelitis optica spectrum disorders (NMOSD) so far have relied on off-label and empiric drugs. The first drug for the therapy of anti-aquaporin-4 (AQP4) antibody-seropositive NMOSD patients has been approved in 2019: the C5 complement inhibitor eculizumab. The interleukin-6 receptor inhibitor satralizumab and anti-CD19 antibody inebilizumab have published positive phase III trial results and await approval in the near future. AREAS COVERED: We sum up current treatment options and portray in detail the new developments in NMOSD drugs focusing on phase III clinical trials, followed by an overview of emerging drugs in less advanced clinical trial stages. EXPERT OPINION: Eculizumab's approval by the competent authorities marks a milestone in NMOSD treatment. Satralizumab and inebilizumab will most likely follow in approval given their presented results in efficacy and safety. All three drugs have shown efficacy in reducing relapse rates in NMOSD patients with anti-AQP4 antibodies. Although we will have even more evidence-based therapy options in the future, empirically used medications will keep their importance for now. The potential effect of new medications in AQP4 antibody-seronegative NMOSD and patients with an NMOSD phenotype and antibodies to myelin oligodendrocyte glycoprotein remains to be determined.