Kinetics of 111In-bleomycin and 111 In-chlorides in mice

Indium-111 as the chloride and chelated to bleomycin has been reported useful as a tumor-scanning agent. This report of the kinetics of these compounds compared in Yale-Swiss mice bearing a transplantable, in situ brain sarcoma. Indium-111-chloride, pH 1.5, gave a maximum tumor uptake of 18.5% dose per gram tumor, a maximum tumor-to-brain ratio of 17.0, and a maximum tumor-to-blood ratio of 4.4. Its renal blood clearance was a slow 0.0022 ml/min. Indium-111-bleomycin showed a maximum tumor uptake of 3.0% dose per gram tumor, a maximum tumor-to-brain ratio of 13.5, a maximum tumor-to-blood ratio of 6.8, and renal blood clearance of 0.254 ml/min. The labeling of bleomycin with 111In results in a tracer with localizing properties in this tumor model which are quite different from those obtained with 111In as chloride or that labeled to bleomycin would appear to have significant potential as agents for imaging tumors.