Localization of biotinylated monoclonal antibodies (B72.3 and F023C5) in patients with colorectal cancer.

: The recognition and treatment of neoplastic lesions in early phases are among the most important aims of research using monoclonal antibodies (MoAb). Recent studies have demonstrated that the use of radiolabelled MoAb directed against tumor associated antigens and hand-held gamma detecting probe (GDP) could help in the recognition of primary tumors and metastases. The goal of this study was to investigate the in vivo antibody reaction as shown by histologic preparations after injection of 125I biotinylated MoAb (B72.3 or F023C5) before surgery and to compare the immunohistochemical results with those obtained with GDP in colorectal cancer. We studied 15 cases of patients with primary or recurrent colorectal cancer. The biotinylated, radiolabelled antibody administered in vivo could be seen in frozen sections with streptoavidin peroxidase complex. In 14 cases there was agreement between GDP observations and detection of the in vivo injected biotinylated MoAb with direct staining using streptoavidin peroxidase conjugate. The use of MoAbs thus provides a means of correlating the intraoperative signal with the presence of the injected antibodies on the tumor.