antiCD20

AntiCD20 refers to monoclonal antibodies that target the CD20 antigen expressed on the surface of most mature B cells. By binding to CD20, these antibodies recruit immune effector mechanisms that lead to depletion of B cells. They are used in treating certain B-cell malignancies and various autoimmune diseases where B cells play a central role. The first and best known example is rituximab, a chimeric antibody approved in the late 1990s, with subsequent agents including ofatumumab, ocrelizumab, obinutuzumab, and ublituximab.

Mechanisms of action vary among agents but share common themes. Binding to CD20 activates immune-mediated pathways such as antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity, and can induce direct B-cell death. Not all mechanisms are identical across drugs, which influences their clinical activity, toxicity, and resistance patterns. Importantly, anti-CD20 antibodies do not target antibody-producing plasma cells, which can limit long-term antibody responses and contribute to relapse if B cells repopulate.

Clinical use spans oncology and autoimmunity. In oncology, anti-CD20 antibodies are used to treat non-Hodgkin lymphomas, chronic lymphocytic leukemia, and mantle cell lymphoma, often in combination regimens or as maintenance therapy. In autoimmune diseases, rituximab and newer agents are used for conditions such as rheumatoid arthritis, granulomatosis with polyangiitis, myasthenia gravis, and multiple sclerosis (notably ocrelizumab). Treatment considerations include infection risk, potential hepatitis B reactivation, infusion reactions, and rare progressive multifocal leukoencephalopathy. Resistance can arise from reduced CD20 expression, antigenic modulation, or changes in immune effector pathways.

Development of anti-CD20 therapies has evolved toward antibodies with improved potency and safety profiles, including humanized or fully human constructs and glycoengineered variants to enhance effector functions.