Update on rituximab: an established treatment for all immune-mediated kidney diseases?

Rituximab, a monoclonal antibody directed against the CD20 antigen, found on certain B-cell subsets, results in significant B-cell depletion and has been increasingly used in immune-mediated renal disease and transplantation. Although originally applied to what were considered antibody-mediated diseases, it has become clear that auto- and alloreactive B cells contribute in many ways to immune dysfunction, and the benefit of B-cell depletion extends beyond reduction in auto- or alloantibody levels. Most positive data regarding the benefit of rituximab in immune-mediated kidney disease have come from uncontrolled cohort studies, with the only positive controlled clinical trials demonstrating efficacy for the treatment of systemic vasculitis. While negative trials may have potentially missed clinical effects due to trial design, there may be significant differences in responses in different diseases or lack of efficacy due to therapeutic overlap when used with certain drug combinations. Rituximab is a novel treatment that provides a clear alternative for patients in different clinical situations, and allows for customization of therapy. However, much remains to be understood as to how best to use it in a cost-effective manner, when not to use it, and what the long-term impact of therapy may be.