Abstract: 6-[18F]Fluoro-2-alkoxynicotinoyl substituted Lys-C(O)-Glu derivatives were identified as efficient imaging probes for PSMA expressing tissues in comparison to other known PSMA specific ligands like [18F]DCFPyL, [68Ga]HBED-CC-PSMA, [18F]PSMA-1007 and [Al18F]HBED-CC-PSMA. Unexpectedly, the 6-[18F]fluoro-2-alkoxy and 6-[18F]fluoro-4-alkoxy substituted analogs showed significant differences in accumulation in PSMA expressing prostate tumor cells. Whereas the 2-alkoxy derivative showed cellular uptake values higher than [18F]DCFPyL, the cellular uptake of the corresponding 4-alkoxy substituted derivative was significantly lower. Furthermore, in vivo PET studies with 2-alkoxy-substituted probes demonstrated excellent visualization of PSMA positive ganglia with extremely high target to background ratio. In contrast, the 4-alkoxy substituted derivatives showed less favorable biodistribution with significantly lower uptake in PSMA positive tissues.

Abstract: 6-[18F]Fluoro-2-alkoxynicotinoyl substituted Lys-C(O)-Glu derivatives were identified as efficient imaging probes for PSMA expressing tissues in comparison to other known PSMA specific ligands like [18F]DCFPyL, [68Ga]HBED-CC-PSMA, [18F]PSMA-1007 and [Al18F]HBED-CC-PSMA. Unexpectedly, the 6-[18F]fluoro-2-alkoxy and 6-[18F]fluoro-4-alkoxy substituted analogs showed significant differences in accumulation in PSMA expressing prostate tumor cells. Whereas the 2-alkoxy derivative showed cellular uptake values higher than [18F]DCFPyL, the cellular uptake of the corresponding 4-alkoxy substituted derivative was significantly lower. Furthermore, in vivo PET studies with 2-alkoxy-substituted probes demonstrated excellent visualization of PSMA positive ganglia with extremely high target to background ratio. In contrast, the 4-alkoxy substituted derivatives showed less favorable biodistribution with significantly lower uptake in PSMA positive tissues.

Abstract: Novel efficient, time-saving and reliable radiofluorination procedures for the production of 18F-labelled active esters via nucleophilic substitution of the corresponding onium precursors with 18F? are described. The active ester including [18F]F-Py-TFP and [18F]TFB produced by one of these methods was used to prepare PSMA-specific PET tracers such as [18F]DCFPyL. The key advantages of these inventive methods are efficiency, short time of preparation and excellent amenability to automation. A pharmaceutical composition containing at least one PSMA-specific PET tracers prepared by the inventive method is useful for positron emission tomography (PET) imaging, especially imaging prostate tumor.

Abstract: Novel efficient, time-saving and reliable radiofluorination procedures for the production of 18F-labelled active esters via nucleophilic substitution of the corresponding onium precursors with 18F? are described. The active ester including [18F]F-Py-TFP and [18F]TFB produced by one of these methods was used to prepare PSMA-specific PET tracers such as [18F]DCFPyL. The key advantages of these inventive methods are efficiency, short time of preparation and excellent amenability to automation. A pharmaceutical composition containing at least one PSMA-specific PET tracers prepared by the inventive method is useful for positron emission tomography (PET) imaging, especially imaging prostate tumor.