Multimodality imaging and preclinical evaluation of 177Lu-AMBA for human prostate tumours in a murine model.

AMBA (DO3A-CH(2)CO-G-(4-aminobenzoyl)-QWAVGHLM-NH(2)) is a bombesin (BN)-like peptide having high affinity with gastrin-releasing peptide receptors (GRPr).(177)Lu-AMBA is currently undergoing clinical trial as a systemic radiotherapy for hormone refractory prostate cancer (HRPC) patients. This study evaluated the biodistribution, pharmacokinetics, bioluminescent imaging (BLI) and microSPECT/CT imaging of (177)Lu-AMBA in PC-3M-luc-C6 luciferase-expressing human prostate tumour-bearing mice. Plasma stability of (177)Lu-AMBA could be maintained up to 55.67±6.07% at 24 h in a protection buffer. High positive correlations of PC-3M luc-C6 tumour growth in SCID mice between caliper measurement and BLI were observed (R(2)=0.999). Both the biodistribution and microSPECT/CT imaging in PC-3M-luc-C6 bearing-tumour mice showed that (177)Lu-AMBA in tumour uptake could be retained for 24 h. The distribution half-life (t(1/2α)) and the elimination half-life (t(1/2β)) of (177) Lu-AMBA in mice were 0.52 h and 26.6 h, respectively. These results indicated that BLI could be used to monitor the growth of tumour. High uptake of (177)Lu-AMBA in PC-3M-luc-C6 tumour-bearing mice by microSPECT/CT imaging can further evaluate the potential of (177)Lu-AMBA therapy for PC-3M-luc-C6 tumours.