VPAC1-targeted PET/CT scan: improved molecular imaging for the diagnosis of prostate cancer using a novel cell surface antigen

Hong Truong, Leonard G. Gomella, Mathew L. Thakur, Edouard J. Trabulsi

Current approaches to prostate cancer screening and diagnosis are plagued with limitations in diagnostic accuracy. There is a compelling need for biomolecular imaging that will not only detect prostate cancer early but also distinguish prostate cancer from benign lesions accurately. In this topic paper, we review evidence that supports further investigation of VPAC1-targeted PET/CT imaging in the primary diagnosis of prostate cancer. A non-systematic review of Medline/PubMed was performed. English language guidelines on prostate cancer diagnosis and management, original articles, and review articles were selected based on their clinical relevance. VPAC1 receptors were overexpressed 1000 times more in prostate cancer than benign prostatic stromal tissue. In vitro and in vivo studies showed that Copper-64 labeled analogs of VPAC1 ligands can be synthesized with high radiochemical efficiency and purity. The radioactive probes had excellent VPAC1 receptor binding specificity and affinity. They had good biochemical stability in vitro and in mouse and human serum. They had minimal urinary excretion, which made them favorable for prostate cancer imaging. Initial feasibility study in men with prostate cancer showed that the probes were safe with no reported adverse reaction.64Cu-TP3805 PET/CT detected 98% of prostate cancer lesions and nodal metastasis as confirmed with whole mount histopathological evaluation. VPAC1 receptors are promising targets for biomolecular imaging of primary prostate cancer that can distinguish malignant from benign lesions non-invasively. Further investigations are warranted to validate initial findings and define the clinical utilities of VPAC1-targeted PET imaging for prostate cancer diagnosis and management.