Rituximab has been successfully used “off label” to treat diseases driven by B-cell dysregulation, but concerns remain about the safety of using rituximab or similar agents for long periods.
B cells play a key role in many autoimmune diseases, including the immune-mediated neurological disorders neuromyelitis optica (NMO), multiple sclerosis (MS), and myasthenia gravis (MG). Rituximab, which causes short-term depletion of circulating naïve and memory B cells through antibody-dependent cell-mediated cytotoxicity, complement mediated cytotoxicity, and induction of apoptosis, has been successfully used “off label” to treat diseases driven by B-cell dysregulation. The promising results of some studies on the use of rituximab in these disorders has generated interest in further developing B-cell depleting or anti-proliferative agents for use in these indications, but concerns remain about the safety of using rituximab or similar agents for long periods.
A study newly published in PLOS One sought to investigate the long-term safety, incidence of infections, and malignancies in patients receiving continuous therapy with rituximab over periods of 36 months to 7 years. The retrospective study was conducted at 2 tertiary centers in Detroit, Michigan, and Chicago, Illinois, and involved 29 patients with diagnoses of MS (n = 5), NMO (n = 21), or MG (n = 3) who received rituximab at doses of 1000 mg via intravenous administration every 6 to 9 months after an initial course of the drug. The mean duration of treatment was 51.3 months (±12.2 months), and the mean number of rituximab treatment cycles was 8.83 (±2.85).
During the observation period:
The study’s authors concluded that rituximab was well tolerated over time in patients with NMO, MS, and MG; that AEs and SAEs remained low throughout the observation period; and that patients remained clinically stable while receiving continuous rituximab infusions. Though the study was small, it makes an important contribution, say the authors, to documenting the long-term tolerability and efficacy of rituximab as a viable option for the treatment of immune-mediated neurological diseases. Further studies will be needed to corroborate these results.