To evaluate effectiveness of subcutaneous (SC) tocilizumab for prevention of relapses in Neuromyelitis Optica Spectrum Disorders (NMOSD). 

Tocilizumab is a humanized monoclonal antibody against the IL-6 receptor approved for treatment of rheumatoid arthritis and temporal arteritis. Intravenous (IV) tocilizumab has been shown to prevent relapses in NMOSD in small case series. However, IV infusion protocols require frequent travel to infusion centers, which may limit patient adherence, especially in disabled patients, thereby reducing efficacy. A SC formulation of tocilizumab has been shown to be noninferior to the IV formulation for rheumatologic conditions. Efficacy of tocilizumab SC as a disease-modifying therapy for NMOSD is unknown. 

Retrospective review of effectiveness of weight-adjusted tocilizumab SC among NMOSD patients attending two tertiary referral centers. 

13 patients on tocilizumab SC were identified (11 females; mean age 46.5±13.9 years, mean disease duration of 6.7±4.4 years ). 8 patients tested positive for AQP4 antibodies, 2 for MOG-IgG Ab, and 3 were doubly seronegative. During tocilizumab SC treatment (mean duration 29.5±19.8 months), 9 patients (69%) were relapse-free, one patient (7.5%) experienced 1 relapse, two patients (15%) - 2 relapses, and one patient (7.5%) - 3 relapses. The number of relapses in the year prior to starting tocilizumab SC was 2.2 ± 2.0 and in the year after starting - 0.6 ± 1.0 (p=0.017). Overall annual relapse rate decreased from 2.9±2.0 before tocilizumab SC to 0.4±0.9 on tocilizumab SC (p=0.0003). 10 patients were on tocilizumab SC at the last follow-up(1 was enrolled in a clinical trial of another agent, 1 didn’t tolerate injections, 1 died after a severe relapse). 

Effectiveness of tocilizumab SC in NMOSD appears to be similar to that reported for the IV formulation and has an advantage of at-home delivery. Prospective study of tocilizumab SC for NMOSD is warranted.