Rituximab also induces a release of some chronic lymphocytic leukemia cells from immune niches, which might make them more sensitive to chemotherapy used in combination with an anti-CD20 antibody.The combined effect results in the elimination of B cells (including the cancerous ones) from the body, allowing a new population of healthy B cells to develop from lymphoid stem cells. Standard treatment protocols of the lead compound rituximab result in rapid (within 3-7 days) and profound (≥90%) depletion of pre-B and mature B cells with full recovery taking as long as 12 months; serum immunoglobulin concentrations may be depleted for 5 to 12 months and may require substitution. Rituximab also leads to a reduced function of B cells as antigen presenting cells and, by increasing immature and transitional B cells, to a dysfunction of CD4+ T cells and abnormal cytotoxic T-cell-specific responses.Rituximab binds to amino acids 170–173 and 182–185 on CD20, which are physically close to each other as a result of a disulfide bond between amino acids 167 and 183.Rituximab is co-marketed by Biogen and Genentech in the U.S., by Hoffmann-La Roche in Canada and the European Union, Chugai Pharmaceuticals, Zenyaku Kogyo in Japan and AryoGen in Iran. History
Rituximab was developed by IDEC Pharmaceuticals under the name IDEC-C2B8. The U.S. patent for the drug was issued in 1998 and expired in 2015.Based on its safety and effectiveness in clinical trials, rituximab was approved by the U.S. Food and Drug Administration in 1997 to treat B-cell non-Hodgkin lymphomas resistant to other chemotherapy regimens.
Therefore, it acts by depleting normal as well as pathogenic B cells while sparing plasma cells and hematopoietic stem cells as they do not express the CD20 surface antigen.In the United States, rituximab is indicated to treat:

non-Hodgkin lymphoma (NHL)
chronic lymphocytic leukemia (CLL)
rheumatoid arthritis having inadequate response to one or more TNF inhibitors
vasculitis 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 B-cell acute leukemia (B-AL). Blood cancers
Rituximab is used to treat cancers of the white blood system such as leukemias and lymphomas, including non-Hodgkins lymphoma, chronic lymphocytic leukemia, and nodular lymphocyte predominant Hodgkins lymphoma. This also includes Waldenströms macroglobulinemia, a type of NHL. 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 (MTX) 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.