Neuromyelitis optica (NMO) is a central nervous system disorder that affects the eye nerves and spinal cord. Azathioprine is the recommended first-line treatment for NMO, and tocilizumab has been reported to reduce the NMO disease activity. This study aims to compare the efficiency and safety of azathioprine and tocilizumab in patients with highly relapsing NMO.

This is an open-label, multi-center, randomized, phase-2 trial conducted at six hospitals in China. The study included 118 patients aged 18 years or more, diagnosed with highly relapsing NMO disease and with a history of at least to clinical relapses in 12 months. The patients were divided into two equal groups and were randomly assigned oral azathioprine (2–3 mg/kg per day) or intravenous tocilizumab (8 mg/kg every four weeks). The minimum-planned treatment was 60 weeks, and the main outcome was the time to first relapse. 

The researchers discovered that the median time to the first relapse was longer in the tocilizumab group than in the azathioprine group. 89% of patients in the tocilizumab group were relapse-free compared to 56% of patients in the azathioprine group.

The research concluded that tocilizumab was more effective in reducing the incidence of NMO disease relapse when compared with azathioprine.