Radioimmunolocalization of Neuroblastoma Xenografts with Chimeric Antibody chCE7

This study was performed to evaluate the tumor targeting ability of chCE7 with a view to clinical applications in neuro blastoma imaging and therapy. A chimeric (mouse/human) monoclonal antibody (chCE7) of gamma 1/kappa isotype directed against a neuroblastoma-associated cell-surface gly-coprotein is described. In vitro chCE7 binds with high affinity(KD ~ 1 x 10~10M) to SKN-AS human neuroblastoma cells. Binding studies with 125l-labeled chCE7 show temperature-dependent modulation of antigen binding and indicate that a proportion of the bound antibody is internalized due to rapid antigen turnover. In vivo biodistribution of radioiodinated chCE7 in nude mice bearing SKN-AS tumors shows optimal tumor uptake after 24 hr with about 30 % of the injected dose per g. Optimal tumor/blood ratios (3.4:1) are reached after 4-5 days. Uptake in other organs including the reticuloendothe-lial system is low with tumor/organ ratios of 10 and more