Radioimmunodetection of prostatic cancer with 125I-labelled antibody against prostatic specific antigen

A murine monoclonal antibody directed against human prostatic specific antigen was labelled with 125I and used in immunoscintigraphy studies of nude mice bearing xenografts of a human prostatic carcinoma cell line (DU-145). The antibody was injected intraperitoneally and the distribution was followed daily with the use of a gamma scintillation camera. Specific uptake was seen in the tumor, with optimal imaging 7-9 days after the injection of the radio-labelled antibody. Fab fragments of the radio labelled antibody were also investigated. These exhibited a strikingly shorter bio-distribution time, with optimal visualization of the tumor after 14-28 hours. Normal murine IgG and Fab fragments used in control experiments exhibited radioactivity that was comparable to that of normal tissue.