VPAC1 Targeted (64)Cu-TP3805 Positron Emission Tomography Imaging of Prostate Cancer: Preliminary Evaluation in Man

To evaluate (64)Cu-TP3805 as a novel biomolecule, to positron emission tomography (PET) image prostate cancer (PC), at the onset of which VPAC1, the superfamily of G protein-coupled receptors, is expressed in high density on PC cells, but not on normal cells.

Twenty-five patients undergoing radical prostatectomy were PET/X-ray computerized tomography imaged preoperatively with (64)Cu-TP3805. Standardized maximum uptake (SUVmax) values were determined and malignant lesions (standardized uptake value > 1.0) counted, and compared with histologic findings. Whole-mount pathology slides from 6 VPAC1 PET imaged patients, 3 benign prostatic hyperplasia patients, 1 malignant and 1 benign lymph node underwent digital autoradiography (DAR) after (64)Cu-TP3805 incubation and were compared to hematoxylin- and eosin-stained slides.

In 25 patients who underwent PET imaging, 212 prostate gland lesions had SUVmax > 1.0 vs 127 lesions identified by histology of biopsy tissues. The status of the additional 85 PET identified prostate lesions remains to be determined. In 68 histologic slides from 6 PET imaged patients, DAR identified 105 of 107 PC foci, 19 of 19 high-grade prostatic intraepithelial neoplasias, and ejaculatory ducts and verumontanum involved with cancer. Additionally, DAR found 9 PC lesions not previously identified histologically. The positive and negative lymph nodes were correctly identified, and in 3 of 3 benign prostatic hyperplasia patients and 5 of 5 cysts, DAR was negative.

This feasibility study demonstrated that (64)Cu-TP3805 delineates PC in vivo and ex vivo, provided normal images for benign masses, and is worthy of further studies.