2-18F-Fluoropropionic acid as a PET imaging agent for prostate cancer

There is a high interest in developing an (18)F-labeled PET tracer that can aid in diagnosis and therapy monitoring of prostate cancer. In the current study, we have evaluated the potential of 2-(18)F-fluoropropionic acid ((18)F-FPA) as a PET tracer for imaging prostate cancer.

(18)F-FPA was synthesized starting from methyl-2-bromopropionate. Small-animal PET studies were performed on mice with CWR22rv1, PC-3, DU-145, and LNCaP prostate xenografts, and comparison of imaging characteristics of (18)F-FPA with (18)F-FDG uptake is reported. Biodistribution studies with (18)F-FPA were performed on mice with CWR22rv1 xenografts and compared with (14)C-acetate.

(18)F-FPA was synthesized in 44% overall radiochemical yield (decay-corrected). Small-animal PET studies revealed that (18)F-FPA can delineate both androgen-dependent and androgen-independent prostate xenografts with high tumor-to-background ratios. Comparative imaging studies demonstrate the superior performance of (18)F-FPA over (18)F-FDG for imaging prostate cancer, with excellent tumor-to-background contrast. Biodistribution studies show that tumor uptake of the tracer was 5.52 +/- 0.35, 5.53 +/- 0.42, 5.74 +/- 0.54, and 5.34 +/- 0.19 percentage injected dose (%ID) per gram at 1, 2, 3, and 4 h, respectively, after injection. The %ID/g values for (18)F-FPA and (14)C-acetate 1 h after tail vein injection were 7.08 +/- 0.80 and 0.36 +/- 0.08 in tumor, and the corresponding tumor-to-muscle ratios were 1.94 and 2.06, respectively.

The data presented here indicate that (18)F-FPA accumulates in prostate cancers with high tumor-to-background ratios. (18)F-FPA has potential for use in the clinical diagnosis of prostate cancer in humans.