Novel 99m Tc-Labeled Mannose Derivative as a Highly Promising Single Photon Emission Computed Tomography Probe for Tumor Imaging.

18 F-2-fluoro-2-deoxy-d-glucose ([ 18 F]FDG) has been the most used positron emission tomography imaging agent for clinical applications. Single photon emission computed tomography (SPECT) imaging is cheaper and used more widely for diagnostic use, but there is no SPECT tumor imaging agent for clinical applications comparable to [ 18 F]FDG. Mannose is a C2 epimer of glucose and can also be transported into tumor cells via glucose transporters (GLUTs). To develop a novel SPECT tumor imaging agent with satisfactory tumor uptake and tumor/nontarget ratios, here a mannose derivative (CN7DM) was synthesized and radiolabeled with technetium-99m to prepare [ 99m Tc]Tc-CN7DM. The six-coordinated structure of [ 99m Tc]Tc-CN7DM was confirmed by the corresponding rhenium compound (Re-CN7DM). [ 99m Tc]Tc-CN7DM was transported into cancer cells via GLUTs and may be trapped in the cancer cells by electrostatic attraction. The probe exhibited high uptake in tumors and low uptake in nontarget tissues in mice bearing different tumors, indicating that [ 99m Tc]Tc-CN7DM exhibited promising potential for SPECT tumor imaging and warranted further clinical investigation.