Comparative serum stability of radiochelates for antibody radiopharmaceuticals.
Serum incubation of monoclonal antibodies chelate labeled by DTPA, benzyl-EDTA and benzyl-TETA with 111In, 57Co, and 67Cu demonstrated marked differences in their stability. In serum, 111In-benzyl-EDTA-antibody was more stable than 111In-DTPA-antibody. Cobalt-57 or 67Cu chelated antibody were less stable than either 111In chelated antibody; 67Cu was only firmly attached to the antibody as 67Cu-benzyl-TETA-antibody. The relative stability of the radiometal chelated antibodies was paralleled by the relative stability in serum of the radiometal chelates themselves. These in vitro studies suggest that in vivo behavior of metal chelates exposed to a complex protein environment cannot be predicted by classical equilibrium constants.
D000911:Antibodies, Monoclonal; D002614:Chelating Agents; D002851:Chromatography, High Pressure Liquid; D003037:Cobalt Radioisotopes; D003300:Copper; D004588:Electrophoresis, Cellulose Acetate; D006801:Humans; D066298:In Vitro Techniques; D007202:Indicators and Reagents / Q000097:blood* / Q000138:chemical synthesis; D007204:Indium; D007553:Isotope Labeling; D011868:Radioisotopes; D011877:Radionuclide Imaging
D000911:Antibodies, Monoclonal; D002614:Chelating Agents; D003037:Cobalt Radioisotopes; D007202:Indicators and Reagents; D011868:Radioisotopes; D007204:Indium; D003300:Copper