Rituximab

Rituximab, sold under the trade names Rituxan® and MabThera®, is a monoclonal antibody used in the treatment of B cell non-Hodgkin's lymphoma, B cell leukaemia, and some autoimmune disorders.

History

Rituximab was developed by IDEC Pharmaceuticals and initially approved by the FDA in 1997 for lymphoma that was refractory to other chemotherapy regimens. The original approval followed the availability of the McLaughlin et al study data. It now is standard therapy in the initial treatment of aggressive lymphomas (eg. diffuse large B cell lymphoma) in combination with CHOP chemotherapy. It is currently co-marketed by Biogen Idec and Genentech in the US market and Roche in the EU.

Mechanism

The antibody binds to the cluster of differentiation 20 (CD20) found on the surface of B cells, flagging them for destruction by the body's own immune system. This eliminates B cells (including the cancerous ones) from the body, allowing a new population of healthy B cells to develop from lymphoid stem cells. The actual mechanisms for Rituximab to eliminate B cells includes the induction of ADCC, CDC, and apoptosis.

Binder et al further described the part of the CD20 molecule that rituximab binds to: it turned out to be amino acids 170-173 and 182-185, which are physically close to each other as a result of a disulfide bond between amino acids 167 and 183.

Non-cancer use

Rituximab has been found to be effective in the treatment of immune thrombocytopenic purpura (ITP) in various trials. It also seems to be effective in threatment of systemic lupus erythematosus and rheumatoid arthritis. In February 2006 the FDA approved Rituxan for Treatment of patients with anti-neutrophil cytoplasmic antibody-associated vasculitis including Wegener's granulomatosis, Microscopic polyangiitis, and Churg-strauss syndrome.

Rituximab has also been found to be effective in the treatment of Acquired pure red cell aplasia (PRCA).

Transplant use

Rituximab is now being used in the management of Renal Transplant recipients. This drug is especially useful in transplants involving incompatible blood groups. It is also used as induction therapy in highly sensitised patients going for renal translplantation.

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