4-fluorotamoxifen and 3-fluoroalanine

To develop ligands for imaging breast tumors, [18F]fluoro analogue of tamoxifen and [18F]fluoroalanine were radiosynthesized. In vivo biodistribution studies were performed in mammary tumor-bearing rats. In studies on the biodistribution of an [18F]fluoro analogue of tamoxifen, tumor uptake decreased when rats were pretreated with diethylstilbestrol (DES), suggesting that tracer uptake in tumors was receptor-mediated. An estrogen receptor assay indicated that tumors have a receptor density of 7.5 fmol/mg protein. Studies of the distribution of [18F]fluoroalanine in tissue showed that the tumor-to-tissue ratio increases as a function of time. Positron emission tomography (PET) images of tumor-bearing rats demonstrated that tumors can be visualized 1 h after rats are injected with an [18F]fluoro analogue of tamoxifen. PET imaging of pigs after injection of 10 mCi of [18F]fluoro analogue of tamoxifen showed uterine uptake that could be blocked by DES (50 mg). The findings suggest that both radiotracers are useful for imaging breast tumors.

Topics: Alanine; Animals; Cell Transplantation; Diethylstilbestrol; Female; Fluorine Radioisotopes; Magnetic Resonance Spectroscopy; Mammary Neoplasms, Experimental; Ovary; Rats; Rats, Inbred F344; Receptors, Estrogen; Swine; Tamoxifen; Tissue Distribution; Tomography, Emission-Computed; Tumor Cells, Cultured; Uterus