A monoclonal antibody that is being studied in the treatment of refractory B-cell non-Hodgkin lymphoma. Monoclonal antibodies are made in the laboratory and can locate and bind to substances in the body, including cancer cells. hA20 binds to the protein CD20, which is found on B cells (a type of immune system cell), and some types of lymphoma cells. Also called HCD20 and IMMU-106.