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tositumomab and iodine I 131 tositumomab
Pronunciation
Definition 1
A combination of drugs used to treat certain types of B-cell non-Hodgkin lymphoma. It is also being studied in the treatment of other types of cancer. Tositumomab and iodine I 131 tositumomab is made up of a monoclonal antibody called tositumomab and a form of tositumomab that is linked to a radioactive substance called iodine I 131. It is a type of radioimmunoconjugate. Also called Bexxar and Bexxar regimen. (NCI Dictionary)
Definition 2
A murine IgG2a lambda monoclonal antibody, both unradiolabeled and radiolabeled with iodine I 131, directed against the human B cell-specific surface antigen CD20. Tositumomab binds to CD20, resulting in complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), and apoptosis in B cells expressing CD20; in addition to the antibody-mediated cytotoxicity, iodine I 131 tositumomab delivers cytotoxic ionizing radiation specifically to CD20-expressing B cells. In a two-step therapeutic regimen, a predose of unradiolabeled tositumomab is administered first followed by the administration of a dosimetric dose of iodine I 131 tositumomab; 7-14 days later, a therapeutic dose of iodine I 131 tositumomab is administered. The predose of unradiolabeled tositumomab binds to nontumor B cells, increasing the terminal half-life of radiolabeled antibody while protecting nontumor B cells from radiolabeled antibody-mediated radiocytotoxicity. (NCI Thesaurus)
Definition 3
A combination of monoclonal antibodies used to treat certain types of non-Hodgkin lymphoma. The monoclonal antibody tositumomab is given with iodine I 131 tositumomab (a form of tositumomab that has been chemically changed by adding radioactive iodine). Monoclonal antibodies are made in the laboratory and can locate and bind to substances in the body, including cancer cells. (NCI Dictionary)
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