Preparation of ²¹²Pb-labeled monoclonal antibody using a novel ²²⁴Ra-based generator solution

Alpha-emitting radionuclides have gained considerable attention as payloads for cancer targeting molecules due to their high cytotoxicity. One attractive radionuclide for this purpose is ²¹²Pb, which by itself is a β-emitter, but acts as an in vivo generator for its short-lived α-emitting daughters. The standard method of preparing ²¹²Pb-labeled antibodies requires handling and evaporation of strong acids containing high radioactivity levels by the end user. An operationally easier and more rapid process could be useful since the 10.6 h half-life of ²¹²Pb puts time constraints on the preparation protocol. In this study, an in situ procedure for antibody labeling with ²¹²Pb, using a solution of the generator nuclide ²²⁴Ra, is proposed as an alternative protocol for preparing ²¹²Pb-radioimmunoconjugates.