Rituximab (trade names "MabThera" by Roche, "Rituxan" by Genetech) is a chimeric monoclonal antibody against the protein CD20 approved in 1997 to treat tumor. It is very effective and shows good tolerance in the treatment of Bcell lymphoma. As people understand more about Bcell and its action mechanism, it is acknowledged that besides Bcell malignancies rituximab can also treat autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus and idiopathic thrombocytopenic purpura. Global sales revenue of rituximab is USD 5,034 million, USD 6,140 million and USD 7,143 million from 2010 to 2012 respectively.