Efficacy and safety of tocilizumab treatment in refractory MOG-IgG related optic neuritis

Myelin oligodendrocyte glycoprotein (MOG) IgG related optic neuritis (ON) which manifests as recurrent episodes and severe visual impairment remains a challenging issue in relapse prevention. Tocilizumab (TCZ), a human monoclonal antibody against IL-6R, may be an alternative treatment for the prevention of relapse in refractory MOG-ON patients.

To investigate the efficacy and safety of Tocilizumab (TCZ) in patients with recurrent myelin oligodendrocyte glycoprotein IgG related optic neuritis (MOG-ON).

We conducted an open-label, single-arm, nonrandomized, uncontrolled clinical trial at a tertiary neuro-ophthalmology center between April 1, 2021, and April 1, 2022.

Participants with relapsed MOG-ON, whose disease had been resistant to previous immunotherapies, received tocilizumab as monotherapy or as an add-on therapy and were followed up for at least 12 months. Annual recurrence rate (ARR), best corrected visual acuity (BCVA), and adverse events were recorded for analyses.

Ten patients (7 females and 3 males) with relapsed MOG-ON were included with a mean (SD) ages of 28.6 (20.5) years old at disease onset and 30.9 (19.7) years at first TCZ administration, with a mean disease duration of 26.6 (11.3) months. Seven (70%) patients remained relapse-free, and the median (range) ARR dropped significantly from 1.9 (0.4-3.5) to 0.0 (0-4.0) during TCZ treatment (p = 0.006). Three patients experienced a relapse of ON at 2, 3, and 7 months after TCZ therapy. The median BCVA improved from 2.7 (2.0-3.0) logMAR at the nadir to 0.2 (0-2.0) logMAR at the last follow-up. Adverse effects included transient diarrhea (n = 1) and upper respiratory infection (n = 1).

This study supports that Tocilizumab therapy, with or without concomitant immunosuppression, is safe and effective in reducing relapses in MOG-ON patients who have failed immunosuppressive therapy or targeted B-cell therapy.

This trial is registered with the Chinese Clinical Trial Registry, number ChiCTR2100045273. (URL: https://www.chictr.org.cn/showproj.html?proj=124810).