Development of an acyclic bifunctional chelator for imaging and therapy of prostate cancer using copper-64 Veronika Rosecker, Ivan Hawala, Tom Price, Maria Rosaria Ruggiero,Graeme Stasiuk King’s College, London UK Copper‑64 (64Cu) is a radioisotope of high interest in nuclear medicine due to its unique decay characteristics and long half-life of 12.7h. This makes it is suitable for shipping over longer distances and for imaging over longer time spans. Furthermore, 64Cu decays either via beta plus or electron capture (61%) or via beta minus decay (39%) making it suitable for imaging via SPECT or PET and even an isotope of therapeutic interest as electron capture leads to the release of Auger electrons.[1] Additionally, copper‑67 (t1/2=61.9h) is an radioisotope of therapeutic interest and thus makes the pair 64Cu /67Cu a theranostic pair of high interest. DOTA and other macrocyclic ligands are known to label copper very well, but are also known for their slow reaction kinetics. Therefore, the interest in acyclic ligands with more favourable reaction kinetics increased in recent years. In our group we developed an acyclic bifunctional hexadentate ligand H3Bn2DT3A.gly which is quantitatively radiolabelled with 64Cu at a broad pH range within minutes at room temperature and ligand concentrations as low as 20µM. Furthermore, the radiolabelled complex showed excellent serum stability with >80% of the complex still intact after 24h. Bioconjugation to a PSMA targeting motif gave the ligand DT3A.PSMA which shows similar excellent radiolabelling behaviour and 90% of the complex still intact after 12h incubation in serum at 37°C. Herein we present the synthesis and the first results of copper-64 radiolabelling of H3Bn2DT3A.gly, its bioconjugated derivative PSMA.DT3A and their biological evaluation.
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