Improved clearance of radiolabeled biotinylated monoclonal antibody following the infusion of avidin as a {open_quotes}chase{close_quotes} without decreased accumulation in the target tumor
- Kyoto Univ., Maebashi (Japan); and others
The techniques of radioimmunoimaging and radioimmunotherapy suffer from prolonged high background radioactivity because intravenously injected antibodies remain in the circulation and in the organs far longer than necessary for effective binding to the target. To decrease background and increase radionuclide excretion without decreasing the dose of radioactivity delivered to the target tumor, we used radiolabeled biotinylated antibodies followed by a {open_quotes}chase{close_quotes} avidin injection. A mouse monoclonal antibody, OST7 (lgG1), which reacts with human osteosarcoma, was biotinylated and labeled with {sup 125}I, {sup 131}I or {sup 22m}Tc. Radiolabeled biotinylated OST7 (10 {mu}g) was administered intravenously into nude mice bearing human osteosarcomas and 30 {mu}g of avidin was injected intravenously 6 or 24 hr later. Following avidin injection in mice pretreated with radiolabeled biotinylated antibodies, radioactivity was promptly cleared from the blood and deposited in the liver and spleen, after which radioiodine was rapidly detached from the antibody and excreted in the urine. The tumor-to-blood ratios at 6 and 24 hr after the injection of {sup 125}I-labeled biotinylated OST7 increased compared with the values before the avidin chase without any loss of tumor radioactivity. Furthermore, the tumor -to-background radioactivity ratio was improved and better images were obtained more rapidly after the injection of radiolabeled biotiny-lated antibodies than with conventional immunoscintigraphy. This method may find application in clinical radio-immunoimaging, especially using short half-life radionuclides such as {sup 39m}Tc and {sup 123}I. 24 refs., 8 figs., 3 tabs.
- OSTI ID:
- 458863
- Journal Information:
- Journal of Nuclear Medicine, Vol. 35, Issue 10; Other Information: PBD: Oct 1994
- Country of Publication:
- United States
- Language:
- English
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