We previously assessed the efficiency of intravenous injections of 125I-labeled mAbs for the treatment of small peritoneal carcinomatosis (Santoro et al, J. Nucl Med 2009). In the present study, athymic nude mice bearing intraperitoneal A-431 tumor cell xenografts expressing CEA receptors were intraperitoneally injected with 125I-35A7 mAb at days 4 following tumor cells xenograft. SPECT-CT imaging shows strong uptake of 125I-mAbs by tumors nodules, and demonstrates its usefulness for radioimmunotherapy of small solid tumors. Tracer details : The non-internalizing murine IgG1k 35A7 mAb, specific for the CEA Gold 2 epitope, was used to target CEA in transfected A-431 cells. Radiolabeling with iodine 125 was done according to the IODO-GEN method.
