(Generic name Rituximab, British name MabThera): the new monoclonal antibody drug that has received US FDA approval for low grade Non-Hodgkin's lymphoma. More on the Rituxan page. econdary Malignancy: cancer that develops after treatment for a first cancer but is not related to the first cancer. Some lymphoma treatments have been linked to a small likelihood of secondary malignancies including solid tumors and leukemia.