Synthesis and evaluation of a novel near-infrared fluorescent probe based on succinimidyl-Cys-C(O)-Glu that targets prostate-specific membrane antigen for optical imaging.

Prostate-specific membrane antigen (PSMA), which is highly expressed in both localized and metastatic prostate cancer (PCa), is an ideal target for imaging and therapy of PCa. We previously reported radiolabeled asymmetric urea derivatives asa PSMA-targeting radiotracer for single-photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging. Here, based on these radiopharmaceutical probes, we designed a novel near-infrared (NIR) fluorescent imaging probe (800CW-SCE) by chemical conjugation between IRDye 800CW-Maleimide and an asymmetric urea compound, known as PSMA inhibitor, for optical imaging. In the in vitro cellular uptake study, 800CW-SCE was internalized into PSMA-positive PCa cells (LNCaP cells) but not into PSMA-negative PCa cells (PC-3 cells). Moreover, in the in vivo imaging study, the probe was highly accumulated in LNCaP tumors but not in PC-3 tumors, and remained in LNCaP tumors until 24h after intravenous administration. These results suggest that the potent NIR conjugate may contribute to clinical intraoperative optical imaging.