Direct labeling of monoclonal antibodies and antibody fragments with 188Re using a weak competing ligand

Different kit formulations for the direct labeling of MoAb-IOR CEA1 and its F(ab')2 fragments with Rhenium-188, using EHDP as a weak competing ligand, were developed. The influence of reaction conditions such as pH, temperature, weak ligand concentration and stannous chloride concentration during the preparation of 188Re-MoAb radioimmunoconjugates, were investigated in detail in order to obtain high radiochemical yields. Results showed that under different reaction conditions, radio-chemical purities over 95% were obtained in 1 to 2 h periods after addition of perrhenate solution eluted from the 188W/188Re generator to a kit formulation. The procedure reported herein demonstrated the overall usefulness for the preparation of pure 188Re-antibody fragments. (orig.)