Long-Term Efficacy and Safety of Low-Dose Rituximab in Patients with Refractory Myasthenia Gravis.

Introduction: Rituximab is a monoclonal chimeric antibody against CD20+ B cells. We aimed to assess the long-term efficacy and safety of CD20+ B cell-guided treatment with low-dose rituximab in refractory myasthenia gravis patients.

Methods: Patients with refractory myasthenia gravis treated with rituximab for more than 2 years were included. Rituximab was administered when CD20+ B cells were greater than 1%. We analysed the efficacy of rituximab, treatment interval, side effects, prognosis, and treatment course.

Results: A total of 22 patients were included. All patients received 2-12 doses of rituximab, and the median follow-up time was 48.5 months. The scores of the Myasthenia Gravis Activities of Daily Living and Myasthenia Gravis Composite were significantly lower than those at baseline (p < 0.05). MGFA-PIS was significantly improved in 21 (95.45%) patients and 14 (63.64%) patients have reached MGFA-PIS minimal manifestations. The average daily dose of prednisone and pyridostigmine bromide and the proportion of immunosuppressants were significantly lower (p < 0.05). Seven patients suffered from 14 worsenings. Eight patients terminated rituximab due to good efficacy. Most patients tolerated rituximab well, although 1 patient had opportunistic infection and hypogammaglobulinemia, 1 patient had an intracranial mass.

Conclusion: Long-term CD20+ B-cell-guided low-dose rituximab showed good efficacy and tolerance in patients with refractory myasthenia gravis.