New Targets for PET Molecular Imaging of Prostate Cancer

Abstract

Prostate cancer (PCa) is the most common cancer in men worldwide, but it exhibits a highly variable biological behavior ranging from indolent to highly aggressive disease. The standard conventional imaging for staging PCa consists of CT, MRI, and bone scans, but this imaging has suboptimal accuracy for extraprostatic tumor detection, particularly in the scenario of early biochemical relapse when the prostate-specific antigen levels are still low indicating a low volume of recurrent disease. This gap between known disease (as indicated by a rising prostate-specific antigen) and the failure to detect it on conventional imaging, has led to the development of novel imaging probes most of which have positron emitting radioactive tags. In the last decade, multiple PET probes have demonstrated promising performance in detecting sites of recurrence and extent of disease in patients with PCa. The landscape of available PET radiotracers is changing rapidly and includes radiolabeled choline, anti1-amino-3-¹⁸F-fluorocyclobutane-1-carboxylic acid (¹⁸F-fluciclovine), bombesin, dihydrotestosterone, and prostate-specific membrane antigen (PSMA) ligands, among others. Of these, radiolabeled PSMA-PET agents have shown the most encouraging results in terms of sensitivity and are likely to become universally available for imaging PCa within a few years Other PET radiotracers such as bombesin-based radiotracers and antagonist of gastrin releasing-peptide receptor (RM2) are emerging as possible alternatives for PCa imaging. This review article discusses the current and near-future of PET molecular imaging probes.