Purpose. This study was to develop an efficient synthesis of99mTc-O-[3-(1,4,8,11-tetraazabicyclohexadecane)-propyl]-α-methyl tyrosine (99mTc-N4-AMT) and evaluate its potential in cancer imaging.Methods. N4-AMT was synthesized by reacting N4-oxalate and 3-bromopropyl AMT (N-BOC, ethyl ester).In vitrocellular uptake kinetics of99mTc-N4-AMT was assessed in rat mammary tumor cells. Tissue distribution of the radiotracer was determined in normal rats at 0.5–4 h, while planar imaging was performed in mammary tumor-bearing rats at 30–120 min.Results. The total synthesis yield of N4-AMT was 14%. Cellular uptake of99mTc-N4-AMT was significantly higher than that of99mTc-N4. Planar imaging revealed that99mTc-N4-AMT rendered greater tumor/muscle ratios than99mTc-N4.Conclusions. N4-AMT could be synthesized with a considerably high yield. Ourin vitroandin vivodata suggest that99mTc-N4-AMT, a novel amino acid-based radiotracer, efficiently enters breast cancer cells, effectively distinguishes mammary tumors from normal tissues, and thus holds the promise for breast cancer imaging.
Design, Synthesis, In Vitro, and Initial In Vivo Evaluation of Heterobivalent Peptidic Ligands Targeting Both NPY(Y1)- and GRP-Receptors—An Improvement for Breast Cancer Imaging?
