Radioimmunodetection of solid tumors. Future horizons and applications for radioimmunotherapy

Seventeen years after the development of hybridoma technology, the clinical utility of radioimmunodetection of solid tumors using monoclonal antibody-based imaging agents has been definitively established. As expected, these first immunoscintigraphy agents demonstrate certain limitations (most notably, suboptimal tumor-to-background radiolocalization ratios and immunogenicity), suggesting that the full potential of this technology has not been realized. This article reviews research strategies for optimizing the imaging performance of radiolabeled monoclonal antibodies. Promising approaches include the development of humanized tumor-targeting vehicles, improved chelator technology to link the antibody and the radioisotope, the use of smaller immunoreactive targeting agents, modifications of the tumor or host determinants of antibody biodistribution, regional delivery of immunoscintigraphic agents, use of antibody "cocktails," and advances in image acquisition technology. The successful application of these strategies should lead to improved agents for tumor radioimmunodetection. The results of these research efforts should be useful in developing radiolabeled monoclonal antibody-based agents for solid tumor therapy.