TECHNETIUM LABELING OF MONOCLONAL-ANTIBODIES WITH FUNCTIONALIZED BATOS .1. TCCL(DMG)3PITC

BATO (boronic acid adduct of technetium dioximes) complexes, TcCl(dioxime)3BR, were prepared in which the boron substituent (R) was the protein-reactive m-phenyl isothiocyanate (PITC). The (TcCl)-Tc-99(dioxime)3PITC complexes [dioxime = dimethylglyoxime (DMG) or cyclohexanedione dioxime (CDO)] were prepared from Tc-99(dioxime)3(mu-OH)SnCl3 and characterized. The X-ray crystal structure of (TcCl)-Tc-99(DMG)3PITC was determined. The Tc-99m complexes were prepared from (TcO4-)-Tc-99m in a process using a freeze-dried kit, either in a one-step procedure or via (TcCl)-Tc-99m(dioxime)3. Initial labeling studies with (TcCl)-Tc-99m(dioxime)3PITC were performed on glycine and polylysine and, subsequently, on mouse IgG and the B72.3 monoclonal antibody. Covalent attachment of (TcCl)-Tc-99m(DMG)3PITC to B72.3 was demonstrated by SDS-PAGE electrophoresis. B72.3 labeled with (TcCl)-Tc-99m(DMG)3PITC displayed high binding to a TAG 72 affinity column and had a distribution in normal mice similar to that reported for iodine-labeled B72.3.