RADIOIMMUNOIMAGING OF COLON-CANCER XENOGRAFTS WITH ANTI-TN MONOCLONAL-ANTIBODY

Tn antigen is a glycosylated tumor associated antigen and a murine mon oclonal antibody, MLS128, has been identified to react with it. The po tential of MLS128 for the radioimmunoimaging of colorectal cancer was studied. MLS128 was labeled with radioiodine by the chloramine-T metho d or indium-lll (In-111) by using isothiocyanatobenzyl EDTA, and was i njected into nude mice bearing human colon cancer xenografts. Radiolab eled MLS128 showed a high and specific localization in xenografted tum or. At 48 h after injection, the %ID/g of I-125-labeled MLS128 in the tumor was 34.69, whereas that of isotype matched control antibody, FLO PC21, was 5.58 and the tumor-to-nontumor radioactivity ratios of I-125 -labeled MLS128 reached to 4.56, 17.84 and 23.62 for the blood, liver and bone, respectively. In-111-labeled MLS128 showed similar results. High accumulation of MLS128 in xenografted tumors suggested that the m onoclonal antibody MLS128 is promising for radioimmunoimaging of color ectal cancer.