Binding of radiolabeled MAb B72.3 administered intravenously and intraperitoneally in colorectal cancer patients. An overview.

Monoclonal antibody (MAb) B72.3 coupled to 131I is currently being used in clinical trials for the diagnostic imaging of gastrointestinal, ovarian, and breast carcinomas. The MAb has also been used extensively in immunohistochemical studies and in the development of radioimmunoassays to define antigen levels in tissues and sera of cancer patients. When administered intravenously, the radionuclide-conjugated MAb has localized tumor in over 70 percent of patients. When intraperitoneal administration was studied, the MAb-radionuclide conjugate successfully imaged peritoneal lesions; moreover, in 3 of 10 patients, B72.3 detected lesions not found by conventional methods. Concomitant administration of 131I labeled B72.3 intraperitoneally and 125I labeled B72.3 intravenously showed that the intraperitoneal route localized peritoneal implants at least two times better than the intravenously administered MAb. Conversely, hematogenously borne or non-implant lesions were better localized with intravenously administered B72.3.