Abstract
This trial was an initial assessment of the feasibility, in vivo targeting, and biokinetics of 16β-18F-fluoro-5α-dihydrotestosterone (18F-FDHT) PET in patients with metastatic prostate cancer to assess androgen receptor expression. Methods: Seven patients with progressive clinically metastatic prostate cancer underwent 18F-FDG and 18F-FDHT PET scans in addition to conventional imaging methods. Three patients had their studies repeated 1 mo later, 2 while on testosterone therapy, and the third after treatment with 17-allylamino-17-demethoxygeldanamycin (17-AAG). High-pressure liquid radiochromatography was used to separate 18F-FDHT from radiolabeled metabolites. Lesion-by-lesion comparisons between the 18F-FDHT, 18F-FDG, and conventional imaging methods were performed. Results: Metabolism of 18F-FDHT was rapid, with 80% conversion within 10 min to radiolabeled metabolites that circulated bound to plasma proteins. Tumor uptake was rapid and tumor retention was prolonged. Fifty-nine lesions were identified by conventional imaging methods. 18F-FDG PET was positive in 57 of 59 lesions (97%), with an average lesion maximum standardized uptake value (SUVmax) = 5.22. 18F-FDHT PET was positive in 46 of 59 lesions (78%), with the average positive lesion SUVmax = 5.28. Treatment with testosterone resulted in diminished 18F-FDHT uptake at the tumor site. Conclusion: 18F-FDHT localizes to tumor sites in patients with progressive clinically metastatic prostate cancer and may be a promising agent to analyze antigen receptors and their impact on the clinical management of prostate cancer.
Footnotes
Received June 20, 2003; revision accepted Oct. 29, 2003.
For correspondence or reprints contact: Steven M. Larson, MD, Department of Nuclear Medicine (SC212), Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY 10021.
E-mail: larsons{at}mskcc.org