Preparation of ⁹⁹Tc^m(CO)₃-BPHRGD and Its Biodistribution in Nude Mice Bearing M21 Human Melanoma Tumor

The ⁹⁹Tc^m(CO)₃-BPHRGD was prepared, and in-vivo biological evaluations in nude mice bearing M21 human melanoma tumor were completed. The labeling yield of ⁹⁹Tc^m(CO)₃-BPHRGD is more than 80% under optimal conditions (pH=7, reacting at 75 ℃ for 30 min), and the radiochemical purity is more than 98% after purification. The in-vitro stability experiments show that the radiolabeled compound has good stability in normal saline and human serum under 37 ℃. The biodistribution of ⁹⁹Tc^m(CO)₃-BPHRGD in nude mice bearing M21 human melanoma tumor shows that the ratio of tumor/blood is 0.70±0.45, 0.87±0.05, 1.10±0.19 and 1.68±0.04 at 0.5, 1, 2 and 4 h respectively. The ratio of T/NT increases with time. This indicates that the clearance rate of this radiolebeled compound in tumor is slower than in other tissues. Through the further structural modification to change metabolic pathways and pharmacokinetic properties, it is very promising as a new tumor imaging agent.