Another monoclonal antibody has been added to the list of targeted anticancer agents available in the U.S. with the approval of Bexxar (tositumomab and I131-tositumomab) for treatment of non-Hodgkin’s lymphoma.

The mouse antibody, which has radioactive iodine attached to it, is specific for the B-lymphocyte surface receptor CD20. In early work at the University of Michigan Comprehensive Cancer Center, the antibody delivered radiation to malignant B-cells while sparing healthy B-cells.

In clinical trials, the antibody treatment produced very promising results among patients with non-Hodgkin’s lymphoma, including patients whose disease had not responded to chemotherapy. The treatment works through a combination of immune system activity mediated by the monoclonal antibody and effects from the radiation released by the iodine 131.

Non-Hodgkin's lymphoma is the sixth leading cause of cancer deaths in the U.S., and it also has the second fastest-growing incidence rate of all cancers. According to the National Cancer Institute, nearly 300,000 Americans have the lymphoma, including roughly 140,000 people with low-grade or transformed low-grade disease.

In more than 30 years, survival rates for people with low-grade non-Hodgkin’s lymphoma have not changed. The additional option of treatment with tositumomab and I131-tositumomab may improve future survival statistics.