64Cu-Hsa-aptamer As A Targeting Agent Recognizes Her2 Expressing Cancer Cell in Vivo

1734 Objectives Human epidermal growth factor receptor-2 (HER2) became one of the most important cancer biomarkers. We determined whether HER2 specific aptamer-albumin conjugates have potential for targeting to HER2 expressing cancer cells in vitro and in vivo. Methods Her2-targeted aptamer was selected and human serum albumin (HSA) conjugated to aptamer for effective circulation. FITC-labeled aptamer was used for confocal microscopy to monitor in vitro targeting. HSA-aptamer was then conjugated with SCN-DOTA and Sulfo-SMCC, and DOTA-HSA-aptamer was labeled with 64CuCl2. Labeling efficiencies of 64Cu-DOTA-HSA-aptamer were checked by ITLC. 64Cu-DOTA-HSA-aptamer was used to monitor tumor targeting in vivo by PET/CT imaging and biodistribution studies. Results FITC-aptamer was clearly detected in HER2 positive cells, but not in negative cells. Labeling efficiency of 64Cu-DOTA-HSA-aptamer was over 95% and in vitro uptake test showed its specificity in HER2-positive tumor cells. In mouse model, successful HER2-targeting was observed by PET/CT, resulting accumulation of 64Cu-DOTA-HSA-aptamer in HER2 positive tumor. Conclusions 64Cu-DOTA-HSA-aptamer was specifically accumulated in HER2 positive tumor tissues, suggesting the possible use of radiolabeled albumin-conjugated aptamer for targeted imaging and therapy