N-(n-Benzylpiperidin-4-yl)-2-[18F]fluorobenzamide: a Potential Ligand for PET Imaging of Breast Cancer

N-(N-Benzylpiperidin-4-yl)-2-[(18)F]fluorobenzamide (2), a potential ligand for PET imaging of sigma receptor, has been found to be a potential agent for detection of breast cancer. In vivo studies in severe combined immunodeficient (SCID) mice bearing MDA-MB231 tumors showed that the uptake of compound 2 in these tumors was high (3.8%/g); the ratios of tumor/muscle and tumor/blood were 6.2 and 7.0, respectively, at 1 h postinjection. Pretreatment of SCID mice with haldol increased the uptake of compound 2 in blood, muscle, and other well-perfused organs while decreasing its uptake in tumors. The ratios of tumor/muscle and tumor/blood decreased from 6.2 and 7.0 to 1.3 and 1.1, respectively, at 1 h postinjection. At 2 h postinjection, the ratios of tumor/muscle and tumor/blood decreased from 4.9 and 7.8 to 1.4 and 1.4, respectively. The tumor uptake of compound 2 in SCID mice bearing primary tumor explants from a human breast cancer patient was lower than that in MDA-MB231 tumors (1.66%/g versus 3.78%/g), and the ratios of tumor/muscle and tumor/blood were 3.5 and 3.7, respectively, at 1 h postinjection. These results suggest that compound 2 may be a potential ligand for PET imaging of breast cancer.