Processing of antibody-radioisotope conjugates after binding to the surface of tumor cells

Abstract

Different radiolabels are processed by tumor cells differently, after catabolism of the antibody to which they originally were conjugated. The data suggest that the prolonged retention of 111In, relative to that of 125I, is due not to deiodination of iodine conjugates, but rather to intracellular retention of catabolic products containing 111In, perhaps within lysosomes. The use of radioisotopes that are retained within cells after antibody internalization and degradation may improve both radioimmunodetection and radioimmunotherapy of cancer.