Preparation and evaluation of [⁶¹Cu]-thiophene-2-aldehyde thiosemicarbazone for PET studies

BACKGROUND: [⁶¹Cu]Thiophene-2-aldehyde thiosemicarbazone ([ ⁶¹Cu]TATS) (4) was prepared according to an analogy of carrier copper compound with antitumor activity, for eventual use in PET. MATERIAL AND METHODS: [⁶¹Cu]TATS was prepared using copper-61 acetate and in-house made ligand (TATS) in one step. ⁶¹Cu was produced via the ^natZn(p,x)⁶¹Cu nuclear reaction (180 μA, 22 MeV, 3.2 h) followed by a two-step chromatography method (222 GBq of ⁶¹Cu ²⁺). [⁶¹Cu]TATS preparation was optimized for reaction conditions (buffer concentration and temperature). The tracer was finally administered to normal rats for biodistribution studies. RESULTS: Total radiolabelling of the tracer took 30 minutes with a radiochemical purity of more than 90% (using HPLC and RTLC) and specific activity of about 250-300 Ci/mmol. The complex was stable in the presence of human serum for an hour. The biodistribution of copper cation and the tracer was checked in wild-type rats for up to 2 hours with significant spleen and lung uptake of the tracer. CONCLUSIONS: The production of ⁶¹Cu via the ^natZn(p,x) ⁶¹Cu is an efficient and reproducible method with high specific activity leading to the production and preliminary evaluation of [ ⁶¹Cu]TATS, a potential PET tracer, was reported.