[ 18F]N-4′-Fluorobenzyl-4-(3-bromophenyl) acetamide for imaging the sigma receptor status of tumors: comparison with [ 18F]FDG and [ 125I]IUDR

• Published in: Nuclear medicine and biology Vol. 28; no. 4; pp. 451 - 458
• Main Authors: Mach, R.H., Huang, Y., Buchheimer, N., Kuhner, R., Wu, L., Morton, T.E., Wang, L.-M., Ehrenkaufer, R.L., Wallen, C.A., Wheeler, K.T.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 2001; Elsevier
• Subjects: Biological and medical sciences; Breast tumors; Contrast media. Radiopharmaceuticals; Medical sciences; PET; Pharmacology. Drug treatments; Sigma receptors; Breast tumors; PET; Sigma receptors; Radionuclide study; Animal model; Radiolabelling; Fluorine; Rodentia; Sigma receptor; Acetamide; Malignant tumor; Experimental study; Mammary gland diseases; Vertebrata; Mammalia; Mouse; Animal; Female; Mammary gland; Pharmacokinetics; Radiopharmaceuticals; Comparative study
• ISSN: 0969-8051; 1872-9614
• DOI: 10.1016/S0969-8051(01)00201-3

A series of biodistribution studies were conducted with the radiotracer, [ 18F]N-(4′-fluorobenzyl)-4-(3-bromophenyl)acetamide, [ 18F] 1 in nude mice bearing tumor xenografts of the mouse mammary adenocarcinoma, line 66. This radiotracer has a high affinity for both σ 1 and σ 2 receptors. In vivo studies were also conducted in order to assess the effect of blocking σ 1 receptors on tumor uptake and the tumor:background ratio of this radiotracer. The results of these studies revealed that blocking the σ 1 receptor so that only the σ 2 receptors are labeled in vivo, results in a higher tumor:background ratio with only a small reduction in the tumor uptake of the radiotracer relative to the no-carrier-added (i.e., nonselective) conditions. Comparative in vivo studies were also conducted with the anatomic and metabolic imaging agent, [ 18F]FDG, and a radiolabeled DNA precursor, [ 125I]IUdR. Both of these radiolabeled compounds represent classes of agents that have been proposed for imaging the proliferative status of solid tumors. The results of these studies indicated that a σ 2-selective imaging agent may be, 1) a better anatomic imaging agent for breast cancer than [ 18F]FDG, and 2) a better functional imaging agent than the radiolabeled DNA precursors, [ 123/124I]IUdR and [ 11C]thymidine, for measuring the proliferative status of breast tumors with PET and SPECT. However, additional studies will be needed to compare σ 2-selective imaging agents with [ 18F]FLT in order to determine which is the more appropriate imaging agent for measuring the proliferative status of breast tumors with PET.