EVALUATION OF TC-99M-LABELED N2S4 COUPLED B72.3 AND LYM-1 ANTIBODIES AS TUMOR-IMAGING AGENTS IN TUMOR-BEARING NUDE-MICE

A new method, using N2S4, for labeling monoclonal antibodies with Tc-99m was developed. To evaluate the utility of this method, two monoclonal antibodies Lym-1, and B72.3 have been studied in tumor bearing nude mice. Biodistribution studies of these mice demonstrated significant tumor localization within 24 hrs post-administration of the Tc-99m labeled antibodies. Tumor uptake of Tc-99m labeled N2S4 coupled Lym-1 was compared to I-131 labeled Lym-1 (labeled by the use of chloramine-T) and was found to give identical tumor to blood ratios. In addition, when Tc-99m labeled Lym-1 was compared with Tc-99m labeled B72.3 tumor uptake was considerably higher in case of Tc-99m labeled B72.3, together with faster clearance from the blood which resulted in a tumor/blood ratio of more than 4.