Tositumomab

Pharmacogenomic Information in the Context of the FDA-Approved Drug Label*

Tositumomab is an anti-neoplastic monoclonal antibody-based regimen targeted against the CD20 antigen, coded for by MS4A2, and found on the surface of normal and malignant B lymphocytes.

The FDA recommends, but does not require, genetic testing prior to initiating or reinitiating treatment with Tositumomab.

Excerpt from the Tositumomab (Bexxar) drug label:
"Tositumomab binds specifically to the CD20 (human B-lymphocyte-restricted differentiation antigen, Bp 35 or B1) antigen. This antigen is a transmembrane phosphoprotein expressed on pre-B lymphocytes and at higher density on mature B lymphocytes. The antigen is also expressed on >90% of B-cell non-Hodgkin¿s lymphomas (NHL). The recognition epitope for Tositumomab is found within the extracellular domain of the CD20 antigen. CD20 does not shed from the cell surface and does not internalize following antibody binding."

For the complete drug label text with sections containing pharmacogenetic information highlighted, see the Tositumomab (Bexxar) drug label PDF.