Optimizing the Radioiodination Conditions of 131I-Rituximab by Chloramine-T

Full text: Rituximab is a monoclonal antibody that has a binding affinity to CD20 antigen. The main function of this antibody is to control initiation and multiplication of cells. CD20 antigen was found in more than 90 percent of Non-Hodgkin's Lymphoma patients. Rituximab has been used as chemotherapeutic agent for Non-Hodgkin's Lymphoma. However in the case of chemotherapeutic non-response patients, a radio immunotherapeutic agent is required. In Thailand, iodine-131 is a suitable radionuclide for this purpose. The objective of this study is focused on optimize the labeling conditions for radioiodination of the antibody by chloramine-T for preparation of I131 Rituximab. It was found that, within 3 minutes of iodination by chlora tine-T, more than 95% of I131 Rituximab was obtained when 7.5 milligram of the antibody was labeled with 75 millicurie of I131 NaI in 0.25 molar of phosphate buffer saline (PBS). The labeled antibody was stable for more than 4 hours