Preparation And Evaluation Of ⁹⁹Tc^m (HYNIC-(Lys³ )-Bombesin)(tricine)(TPPTS)for Imaging The Balb/C Nude Mice Bearing Human Pancreatic Cancer

Objective: To synthesize [⁹⁹Tc^m(-HYNIC-[Lys³]-Bombesin)(tricine)(TPPTS)] and evaluate its biodistribution and binding capability with tumor tissue in Balb/c nude mice bearing human pancreatic cancer xenografts.Methods: HYNIC was conjugated to the [Lys³]-Bombesin at PH=9.0 and SnCl2 as reducing agent,tricine and TPPTS(Tris(3-sulfonatophenyl)phosphine,sodium salt) as coligands were also utilized for ⁹⁹Tc^m-labeling, [⁹⁹Tc^m-HYNIC-[Lys³]-Bombesin)(tricine)(TPPTS)] was purified by Sep-Pak C-18 cartridge and was analysed by HPLC. The radiochemical purity ,the radiolabeling yield were analysized. The stability of [⁹⁹Tc^m-(HYNIC-[Lys³]-Bombesin)(tricine)(TPPTS)] in serum, biodistribution in the normal mice and imaging the Balb/c nude mice bearing human pancreatic cancer xenografts in vivo were studied.Results: The radiolabeling yield reached 90±2% and the radiochemical purity is over 95%. The radiochemical purity after 4 h in serum is still over 85%. The distribution in normal mice showed it rapid clear from blood(the uptake is 0.07±0.01%ID/g at 2 h postinjection ). [⁹⁹Tc^m-(HYNIC-[Lys³]-Bombesin)(tricine)(TPPTS)] is excreted mainly via the renal route with little radioactivity accumulation in the liver and gastrointestinal tract(the uptake of liver, stomach, intestine is 0.27±0.03%ID/g,0.06±0.03%ID/g, 0.04±0.00%ID/g at 2 h postinjection). Abnormal and marked uptake of radioactivity was found in tumor tissue of the Balb/c nude mice bearing human pancreatic cancer. It had the best T/NT ratio (3.71±0.57) at 2 h postinjection. Conclusion: [⁹⁹Tc^m-(HYNIC-[Lys³]-Bombesin)(tricine)(TPPTS)] can be easily prepared and had high radiolabeling yield and high radiochemical purity. Due to its high stability in serum and favorable biodistribution, As a radiotracer, it might be used for the diagnosis of human pancreatic cancer that over-express the GRP(gastric-releasing peptide) receptor.