MabThera, also known by its generic name rituximab, is a monoclonal antibody used in the treatment of various types of cancer, including non-Hodgkin's lymphoma and chronic lymphocytic leukemia, as well as certain autoimmune diseases, such as rheumatoid arthritis. It works by targeting and destroying B cells, a type of white blood cell that plays a role in both the immune response and the development of many cancers and autoimmune disorders. MabThera operates by binding to the CD20 protein found on the surface of B cells, leading to their destruction. This medication is typically administered through intravenous infusion and is often used in combination with other chemotherapy drugs or treatments to enhance its effectiveness. Its use has significantly improved outcomes for patients with these conditions, making it a vital component of modern therapeutic regimens.