Radioimmunoimaging of Local Recurrence of Rectal Cancer by Radiolabeled Mouse Monoclonal Antibody A7

Though the definite diagnosis of local recurrence of rectal carcinoma is still difficult, recent rapid development of new diagnostic tools such as ultrasonography, X-ray CT and MRI brought us many information of mass lesion in the body. One of the most promising approaches to clarify the nature of mass lesion is radioimmunoimaging by radiolabeled tumor specific monoclonal antibody. We had developed mouse monoclonal antibody A7 that is reacted with human adenocarcinoma including colorectal cancer. A7 reacted with glycoprotein that is expressed on the cell surface of cancer. The molecular weight of glycoprotein is 42kD and is proved to be different from CEA and CA19–9. Selective accumulation of 1311-labeled A7 to human cancer tissue was observed in nude mouse model. And 1311-labeled A7 is applied for patients who had mass lesion which suspected to be local recurrence of colorectal carcinoma. Five Mci of radiolabeled A7 diluted in saline was administered intravenously for five patients. One, 2, 3 and 7 days after injection the planner or/and SPECT images of the lesion were obtained by digital gamma camera.