Preparation of TH 227 -Labeled Radioimmunoconjugates,Assessment of Serum Stability and Antigen Binding Ability

In this study, the feasibility of constructing radioimmunoconjugates by using the novel therapeutic candidate alpha-emitter, ²²⁷Th, was evaluated. By use of the bifunctional chelator, p-SCN-benzyl-DOTA, ²²⁷Th was conjugated to the two monoclonal antibodies, rituximab and trastuzumab. Their stability in 80% fetal bovine serum at 37°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 radioimmunoconjugates demonstrated a relevant stability in serum and showed appropriate antigen-binding abilities.