PET imaging of tumor metastasis using 68Ga-labeled a novel tumor-homing peptide TMTP1

1086 Objectives Tumor metastasis is one of the major obstacles to cancer therapy and the primary cause of cancer-related death. Development of new method to detect metastases, especially occult metastases, is urgently needed. In this study, a novel selective peptide sequence termed TMTP1 (NVVRQ) was labeled with 68Ga, and the properties of targeting metastatic tumors was assessed. Methods 68Ga-TMTP1 was prepared with DOTA as the bifunctional chelator. Highly metastatic MDA-MB 231 human breast tumor xenograft model and lowly metastatic MCF-7 human breast tumor xenograft model were used for 68Ga-TMTP1 PET imaging. The scrambled variant peptide (VNQRV, named svTMTP1) was used as a control. Results 68Ga-TMTP1/svTMTP1 displayed high labeling yield (>98%) and high specific activity (~2.5 Ci/μmol). The microPET imaging of 68Ga-TMTP1 showed fast tumor targeting and a good tumor contrast in both original and metastatic MDA-MB-231 tumors, but showed relatively low tumor-targeting efficiency in lowly metastatic MCF-7 tumor. Compared to 68Ga-TMTP1, the 68Ga-svTMTP1 showed no uptake in MDA-MB-231 tumor. Conclusions Our results indicate that the 68Ga-TMTP1 is a promising imaging agent for the early detection of highly metastatic tumors. The further investigation is in progress.