MicroPET-CT imaging for evaluation of PSMA expression in Prostate cancer with newly prepared 68Ga-PSMA-11

1391 Objectives The aim of this study was to synthesize Prostate-specific membrane antigen (PSMA) targeted 68Ga-PSMA-11 at room temperature and evaluate PSMA expression in nude mice tumor model with 68Ga-PSMA-11 micro PET-CT imaging. Methods 68Ga-PSMA-11 was prepared at room temperature. Its radiochemical yield and radiochemical stability were determined via RP-HPLC. Prostate cancer cell lines of different PSMA expression level (LNCap ++, CWR22RV1+ and PC3 -) was selected for cell-based and animal-based studies. The specific cell uptake and internalization of 68Ga-PSMA-11 was determined in cell-based assay. Nude mice bearing prostate cancer xenograft was selectd for biodistribution studies and microPET-CT imaging. PSMA expression was evaluated by microPET-CT imaging and confirmed by immunohistochemistry and PCR. Results 68Ga-PSMA-11 was stable in vitro and its radiochemical purity was (95.8±3.6)% 3h after radiolabeling. The 50% inhibitory concentration (IC50) was 26.8 ± 1.7 nMol/L. The surface-bound fraction and the intra-cellular binding fraction were measured respectively and tumor uptake per cent of Initially Applied radioactivity bound to 106 cells [%IA/106 cells] was (3.6 ± 1.01) and (0.92 ±0.23). Blood elimination of 68Ga-PSMA-11was fast while its uptake by the liver and kidneys were relatively low. Tumor (LNCap) uptake (%ID/cm3) of 68Ga-PSMA-11 reached peak (13.32±1.41) at 60min, higher than that of CWR22RV1(10.32±1.08), PC3 (1.23±0.34). Correlationship was found between tumor uptake of 68Ga -PSMA-11 and PSMA expression( r=0.89, p Conclusions 68Ga-PSMA-11 microPET-CT imaging may have great potential for targeted evaluation of PSMA expression level and be of great value in the clinical management of prostate cancer.