Preparation of TH227-labeled radioimmunoconjugates, assessment of serum stability and antigen binding ability

In this study, the feasibility, of constructing radioimmumoconjugates by using the novel therapeutic candidate alpha-emitter, Th-227, was evaluated. By use of the bifunctional chelator, p-SCN-benzyl-DOT, 227 was conjugated to the two monoclonal antibodies, rituximab and trastuzumab. Their stability in 80% fetal bovine serum at 37 degrees C was measured. The immunoreactive fractions were determined by using CD20-and HER/2-positive cells, respectively. The overall labeling yield spanned from 6% to 17%. The radiomimmununoconjugates demonstrated a relevant stability in serum and showed appropriate antigen-binding abilities.