Hematological Malignancies

131 I Tositumomab (Anti-B1): Mechanism Of Action

• Tositumomab

– Murine IgG2a anti-CD20 mAb – Triggers apoptosis, via unique epitope

• Iodine-131 radioisotope – Beta emission

• Short pathlength “crossfire” effect (~1 mm)

– Gamma emission

• Allows individual dosimetry • Essential component of treatment