Rituximab has been used in the in the treatment of severe lupus for many years. It works by depleting the antibody producing B cells in lupus patients.
However, two large studies failed to show that it was better than a placebo drug in patients with severe lupus. It is unlikely ever to get a license for use in lupus but it remains widely used by many lupus clinics around the world.
Reference
Díaz-Lagares C, Croca S, Sangle S, Vital EM, Catapano F, Martínez-Berriotxoa A, García-Hernández F, Callejas-Rubio JL, Rascón J, D'Cruz D, Jayne D, Ruiz-Irastorza G, Emery P, Isenberg D, Ramos-Casals M, Khamashta MA; UK-BIOGEAS Registry. Efficacy of rituximab in 164 patients with biopsy-proven lupus nephritis: pooled data from European cohorts. Autoimmun Rev. 2012;11:357-64.