Experimental study of 99Tcm-tri-peptide as a novel tumor imaging agent

Objective: To evaluate 99Tcm-Arg-Glu-Ser (99Tcm-RES) as a potential tumor imaging agent. Methods: RES was synthesized using solid phase peptide synthesis. The optimal labeling conditions of RES were determined under different reagents and reacting temperatures using SnC12 as reducing agent.The biodistribution of 99Tcm-RES was studied in nude mice bearing human lung cancer A549. Results: The radiochemical purity of 99Tcm-RES was up to 85% and the radiochemical purity was 75% ever after 6 h at room temperature. The tumor uptake of 99Tcm-RES was obvious and the radioactivity ratios of tumor/blood, tumor/heart, tumor/liver, tumor/lung, tumor/spleen and tumor/muscle were 5.31, 1.88, 1.57, 3.58, 4.16 and 5.92, respectively at 6 h after 99Tcm-RES injection. Gamma camera imaging showed that tumor uptake of 99Tcm-RES was negative in rabbits with inflammatory mass but positive in those bearing tumor. The radioactivity ratio of tumor/inflammation was 3.12 at 6 h after injection. Conclusion: 99Tcm-RES might possibly become a potential tumor imaging agent. (authors)