Prostate-specific membrane
antigen (PSMA) is a transmembrane
protein that is highly expressed in aggressive
prostate cancer (PCa) and has been extensively studied as a PCa diagnostic imaging
biomarker. Multiple imaging modalities have exploited PSMA as a
biomarker including magnetic resonance (MR), Optical, and PET imaging. Of all the imaging MR imaging provides the most detailed information, concurrently providing anatomical, functional, and potentially molecular information. However, the lower sensitivity of MR requires development of molecular MR
contrast agents that provides high signal-to-noise ratios. Herein, we report the first targeted and activatable Gd(III)-based MR
contrast agents prostate cancer probe 1 and 2 (PCP-1 and -2). We successfully used PCP-2 to differentiate between PSMA+ and PSMA-
prostate cancer cells with both in vitro fluorescence imaging and in vivo MR imaging. The in vivo MR imaging results were further supported by ex vivo fluorescence imaging studies, showcasing the unique bimodal feature of PCP-2. Furthermore, PCP-2 highlights a unique molecular MR probe design strategy that improved the sensitivity of traditional
biomarker-targeted MR imaging, addressing a critical unmet need in molecular MR imaging field. This work represents the first example of a targeted and activatable MR
contrast agent that can be systemically administered in vivo to highlight PSMA+ prostate
tumors, paving the way for the clinical translation of MR PSMA imaging.