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

Indium-111 as the chloride and chelated to bleomycin has been reported useful as a tumor-scanning agent. This is a 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 percent 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 percent 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-chloride. Both 111In as chloride or that labeled to bleomycin would appear to have significant potential as agents for imaging tumors. (U.S.)