Rituximab in the treatment of dermatomyositis and other inflammatory myopathies. A report of 4 cases and review of the literature

Objective. Rituximab is an anti-CD20 monoclonal antibody targeting B cells, which has been used with success in a wide variety of autoimmune diseases. The experience with this drug in patients with inflammatory myopathies (IM), nonetheless, is still limited. We review the literature and highlight several aspects in relation to therapy with rituximab in IM. Methods. We performed a research in the MEDLINE DATABASE. All cases identified front the literature research and cases diagnosed in our Unit were included in the analysis. Results. We identified 49 patients with IM treated with rituximab in the review of the literature carried out (31 female; 18 male), including our patients. Dermatomyositis (DM) was the most common disorder for which rituximab treatment was administered (69.4%). The other diseases treated included polymyositis (PM) 16.3%, antisynthetase syndrome (AS) 8.2%, one case with anti-SRP-syndrome and other with juvenile dermatomyositis. The median time to diagnosis was 48 (0.75-480) months. Sixty-five per cent (65.3%) of patients presented with skin manifestations, 89.8% with muscle weakness, 7.3% with arthritis, 16.3% with interstitial lung disease, and 7.3% with cardiomyopathy. Seventy-one (71.4%) of the patients received only one course of rituximab, 18.4% two courses, 4.1% three, 2% four and only 4.1% five. We have observed both among our patients and those reported in the literature a high rate of response to rituximab, 75% of our patients and 72.5% of those described in the literature showed a good response. The median time free of symptoms between two courses was 12 (6-19) months. Rituximab was generally well tolerated by all patients, with no serious adverse events. Most of the adverse events reported were mainly infections, particularly respiratory tract infections. Conclusions. It is our belief that rituximab may be an optimal therapeutic choice for inflammatory myopathies. Nevertheless, there is a need for additional studies in order to assess the optimal regimen of treatment in the different subsets, as well as the initial dose, combination of treatments and re-treatment schedule.