Bexxar, a radioligand therapy using the radioisotope I-131+Tositumomab (a murine monoclonal antibody) and binding/targeting the ligand CD20 on human B-cells. CD20 is a membrane spanning protein found on B-cell lymphocytes that is a tumor marker as it is in higher concentration in cancer patients - specifically leukemias or lymphomas (like non-hodgkin's lymphoma).
I-131 is produced by nuclear fission or through neutron irradiation of Te-130 to convert it to Te-131 which decays to I-131 (produced in the University of Missouri Research Reactor). I-131 is stored in lead-shielding vials.
24 hours before and 14 days after administration, thyroid protective drugs and KI tablets are administered. I-131 and Tositumomab are administered separately over the course of 14 days intravenously by dosimetric and therapeutic doses. Side-effects include anemia, fever, rigors or chills, sweating, hypotension, dyspnea, bronchospasm, and nausea. There is a risk of radiation exposure to other individuals (women/children/fetus), anaphylaxis, neutropenia (low neutrophils), and thrombocytopenia (low platelet).
Zevalin, another radioligand therapy that targets non-Hodgkin lymphoma CD20 ligand but using Yttrium-90 as the radioisotope, was FDA approved in 2002.