Scintigraphic detection of xenografted renal tumor by anti-renal cancer monoclonal antibody radiolabeled with technetium-99m.

Accumulation in the tumor of the RCS-1 monoclonal antibody, which recognizes the cell surface antigen of renal cancer cells was examined. The antibody purified by affinity chromatography (protein-A column) and gel fractionation was labeled with technetium-99m (99mTc) by a direct method. High labeling efficiency (> 98%) could be routinely obtained. However, the 99mTc labeling of the antibody did not reduce the reactivity of the RCS-1 antibody. The labeled antibody was injected into nude mice transplanted with human renal and gastric tumors, and the accumulation of the antibody in each tumor and various tissues was compared at 48 hours after injection. The highest accumulation of radiolabeled RCS-1 antibody was observed in the AM-RC-3 renal tumors; at 8.0% of the injected dose per gram and a tumor-to-blood ratio of 1.05, respectively. However, the radiolabeled RCS-1, did not show specific accumulation in the gastric tumor nor in any tissues tested. The xenografted tumor, AM-RC-3 was successfully visualized with the radiolabeled RCS-1 antibody by scintigraphy.