Preliminary analysis of mortality associated with rituximab use in autoimmune diseases

Normal antibodies and pathogenic autoantibodies are produced by B-cells and plasma cells. Rituximab is a chimeric monoclonal antibody that targets the CD20 molecule on cells that express them on their surface and kills them. Rituximab has been increasingly used to treat several autoimmune diseases. Studies on fatal outcomes associated with rituximab therapy are lacking. A comprehensive and detailed analysis in which the multiple factors that could contribute to a fatal outcome in all the autoimmune diseases in which rituximab has been used would be cumbersome, lack uniformity and would prove difficult in making certain definitive conclusions and comparisons, but more importantly it would not allow to provide specific precautions and recommendations to prevent mortality. Hence, autoimmune mucocutaneous blistering diseases (AMBD) were used as model to study fatal outcomes in patients treated with rituximab between 2000 and 2013, using uniform 13 criteria. Fatal outcomes were found in 14 patients with autoimmune blistering diseases out of 134 patients (10.4%). Patients died due to infections (75%), gastrointestinal (17%) and cardiac events (8%). Causes of death were reported in 101 patients with other autoimmune diseases out of 4320 with a mortality rate of 2.4%. Among them, 44 patients (43.6%) died from infections. A statistical analysis of the data demonstrated that a statistically significant higher mortality rate was observed in patients with AMBD compared to patients with other autoimmune diseases. Similarly, a statistically significant higher rate of death due to infections was reported in patients with AMBD compared to patients with other autoimmune diseases. Use of systemic corticosteroids and immunosuppressive agents as concomitant therapy with rituximab enhanced immunosuppression. In many patients, B-cells were depleted for prolonged periods, even after clinical recovery was observed. Although its main action is depletion of B-cells, rituximab has a significant impact on the immune and inflammatory systems, directly and indirectly and thus enhances susceptibility to infection. These preliminary data suggests that physicians using rituximab to treat autoimmune diseases should monitor their patients closely, especially their B-cell levels until they return to normal, be vigilant for possible sources of infection, and be aware of potential fatal outcomes.