Synthesis, Biodistribution, and Estrogen Receptor Scintigraphy of Indium-111—Diethylenetriaminepentaacetic Acid–Tamoxifen Analogue

Abstract

This study was aimed at developing a hydrophilic diethyl-enetriaminepentaacetic acid–tamoxifen (DTPA–Tam) analogue for use in imaging estrogen receptor positive (ER+) lesions. In rat uterine cytosol, the IC50 of DTPA-Tam conjugate was 1 µM and of tamoxifen, 2 µM. Biodistribution, autoradiography, and radionuclide imaging of 111In–DTPA–Tam in breast-tumor-bearing rats showed that tumor-to-tissue ratios increased steadily between 30min and 48h. The in vivo response of MCF-7 breast cancer xenografts to tamoxifen and DTPA–Tam in nude mice demonstrated that DTPA–Tam could reduce tumor growth rate. These results indicate that DTPA–Tam, a new hydrophilic ER+ ligand, might be useful in diagnosing ER+ lesions.