indication

For treatment of non-Hodgkin's lymphoma (CD20 positive, follicular)

pharmacology

Tositumomab binds to the CD20 antigen, which is predominantly expressed on mature B cells and on >90% of B-cell non-Hodgkin's lympohomas. The antibody leads to selective killing of B-cells.

mechanism of action

Binds to the CD20 antigen which is found on mature B lymphocytes. The antibody binding appears to induce apoptosis, complement-dependent cytotoxicity and cell death through ionizing radiation.

biotransformation

Most likely removed by opsonization via the reticuloendothelial system when bound to B lymphocytes, or by human antimurine antibody production

half life

0.8 hours (mammalian reticulocytes, in vitro)

route of elimination

Elimination of Iodine-131 occurs by decay and excretion in the urine.

drug interactions

Natalizumab: The immunosuppressant, Tositumomab, may increase the adverse effects of Natalizumab. Increased risk of Progressive Multifocal Leukoencephalopathy (PML) and other infections. Concurrent therapy should be avoided.

Trastuzumab: Trastuzumab may increase the risk of neutropenia and anemia. Monitor closely for signs and symptoms of adverse events.