Rituximab, sold under the brand name Rituxan among others, is a monoclonal antibody medication used to treat certain autoimmune diseases and types of cancer, as well as for prevention and/or treatment of antibody-mediated rejection of organ transplants. It is used for non-Hodgkin lymphoma, chronic lymphocytic leukemia, rheumatoid arthritis, granulomatosis with polyangiitis, idiopathic thrombocytopenic purpura, pemphigus vulgaris, myasthenia gravis and Epstein–Barr virus-positive mucocutaneous ulcers. It is given by slow intravenous infusion. The most common side effects with intravenous infusions are reactions related to the infusion (such as fever, chills and shivering) while most common serious side effects are infusion reactions, infections and heart-related problems. Similar side effects are seen when it is injected under the skin, with the exception of reactions around the injections site (pain, swelling and rash), which occur more frequently with the skin injections. Severe side effects include reactivation of hepatitis B in those previously infected, progressive multifocal leukoencephalopathy, toxic epidermal necrolysis, and death. It is unclear if use during pregnancy is safe for the developing fetus or newborn baby. Rituximab is a chimeric monoclonal antibody against the protein CD20, which is primarily found on the surface of immune system B cells. When it binds to this protein it triggers cell death. Rituximab was approved for medical use in 1997. It is on the World Health Organization's List of Essential Medicines. Rituxan is co-marketed by Biogen and Genentech in the US, by Roche elsewhere except Japan, and co-marketed by Chugai Pharmaceuticals and Zenyaku Kogyo in Japan.
Medical uses Rituximab is a chimeric monoclonal antibody targeted against CD20, a surface antigen present on B cells. It acts by depleting normal as well as pathogenic B cells while sparing plasma cells and hematopoietic stem cells, which do not express the CD20 surface antigen. In the United States, rituximab is indicated to treat:
non-Hodgkin lymphoma chronic lymphocytic leukemia rheumatoid arthritis having inadequate response to one or more TNF inhibitors vasculitides such as granulomatosis with polyangiitis and microscopic polyangiitis moderate to severe pemphigus vulgaris in combination with chemotherapy for children (≥ 6 months to < 18 years) with previously untreated, advanced stage, CD20-positive diffuse large B-cell lymphoma (DLBCL), Burkitt lymphoma (BL), Burkitt-like lymphoma (BLL), or mature acute B-cell leukemia (B-AL) antibody-mediated rejection of transplanted organs. In the European Union, rituximab is indicated for the treatment of follicular lymphoma and diffuse large B cell non-Hodgkin's lymphoma (two types of non-Hodgkin's lymphoma, a blood cancer); chronic lymphocytic leukemia (CLL, another blood cancer affecting white blood cells); severe rheumatoid arthritis (an inflammatory condition of the joints); two inflammatory conditions of blood vessels known as granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA); moderate to severe pemphigus vulgaris, an autoimmune disease characterised by widespread blistering and erosion of the skin and mucous membranes (the linings of internal organs). 'Autoimmune' means that the disease is caused by the immune system (the body's natural defences) attacking the body's own cells.
Blood cancers Rituximab is used to treat cancers of the white blood system such as leukemias and lymphomas, including non-Hodgkin's lymphoma, chronic lymphocytic leukemia, and nodular lymphocyte predominant Hodgkin's lymphoma. This also includes Waldenström's macroglobulinemia, a type of non-Hodgkin lymphoma. Rituximab in combination with hyaluronidase human, sold under the brand names MabThera SC and Rituxan Hycela, is used to treat follicular lymphoma, diffuse large B-cell lymphoma, and chronic lymphocytic leukemia. It is used in combination with fludarabine and cyclophosphamide to treat previously untreated and previously treated CD20-positive chronic lymphocytic leukemia.
Autoimmune diseases Rituximab has been shown to be an effective rheumatoid arthritis treatment in three randomised controlled trials and is now licensed for use in refractory rheumatoid disease. In the United States, it has been FDA approved for use in combination with methotrexate for reducing signs and symptoms in adult patients with moderately to severely active rheumatoid arthritis (RA) who have had an inadequate response to one or more anti-TNF-alpha therapy. In the European Union, the license is slightly more restrictive: it is licensed for use in combination with methotrexate in patients with severe active RA who have had an inadequate response to one or more anti-TNF therapy. There is some evidence for efficacy, but not necessarily safety, in a range of other autoimmune diseases, and rituximab is widely used off-label to treat difficult cases of multiple sclerosis, systemic lupus erythematosus, chronic inflammatory demyelinating polyneuropathy and autoimmune anemias. The most dangerous, although among the most rare, side effect is progressive multifocal leukoencephalopathy infection, which is usually fatal; however, only a very small number of cases have been recorded occurring in autoimmune diseases. Other autoimmune diseases that have been treated with rituximab include autoimmune hemolytic anemia, pure red cell aplasia, thrombotic thrombocytopenic purpura (TTP), idiopathic thrombocytopenic purpura (ITP), Evans syndrome, vasculitis (e.g., granulomatosis with polyangiitis), bullous skin disorders (for example, pemphigus, pemphigoid—with very encouraging results of approximately 85% rapid recovery in pemphigus, according to a 2006 study), type 1 diabetes mellitus, Sjögren's disease, anti-NMDA receptor encephalitis and Devic's disease(Anti-AQP4 disease, MOG antibody disease), Graves' ophthalmopathy, autoimmune pancreatitis, Opsoclonus myoclonus syndrome (OMS), and IgG4-related disease. There is some evidence that it is ineffective in treating IgA-mediated autoimmune diseases.
Organ rejection Rituximab is used off-label for treating antibody mediated rejection (AMR) in transplant patients.
Adverse events Serious adverse events, which can cause death and disability, include:
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![Rituximab: Rituximab mechanisms of action; the three major independent mechanisms are (1) antibody dependent cellular cytotoxicity (ADCC), (2) complement mediated cytotoxicity (CMC), and (3) apoptosis; subset panel illustrates a schematic view of CD20 structure and rituximab.[61]](https://upload.wikimedia.org/wikipedia/commons/thumb/7/79/Rituximab_mechanisms_of_action.jpg/500px-Rituximab_mechanisms_of_action.jpg?utm_source=en.wikipedia.org&utm_campaign=parser&utm_content=thumbnail)

