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[摘要]：Peptide targeted Cu-64-labelled diagnostic agents for positron emission tomography are viable candidates for molecular imaging of cancer. In a clinical setting, optimal image quality relies on selective tumor uptake of the Cu-64-labelled radiotracer. The three components of the radiotracer construct - the chelate group, linker and targeting peptide - all influence the biodistribution of the Cu-64-labelled radiotracer in vivo. Low or moderate Cu complex stability in vivo results in transmetallation of Cu-64 to endogenous proteins, giving rise to high background activity. The length and the nature of the linker group affect the affinity of the Cu-64-labelled radiotracer for the target receptor. Variations in the peptide sequence can impact on the metabolic stability and therefore the bioavailability and tumor retention of the Cu-64-labelled radiotracer in vivo. Lastly, the hydrophilicity of the construct can influence radiotracer metabolism and clearance pathways. Recent advances in the field of peptide targeted Cu-64-labelled radiopharmaceuticals involve GRPR-targeted and alpha v beta 3 integrin receptor-targeted constructs. These constructs are based on the bombesin peptide sequence and the RGD recognition motif respectively. These examples are reviewed as case studies in the optimisation of Cu-64 radiotracer design. |
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