Biodistribution of Novel 68 Ga Radiolabelled HER 2 Aptamers in Mice
Background: Two novel HER2 aptamers were recently selected with great potential for the in vitro diagnosis of HER2 positive cancer. The goal of this study was to examine the in vivo diagnostic potential of these HER2 aptamers. Methods: Both HER2 aptamers were radiolabelled with 68Ga, injected in mice bearing a HER2 positive and HER2 negative tumour and evaluated by PET/MRI. Results: Ex vivo bio distribution analysis revealed high uptake in the blood, tissues and organs, except the brain. Interestingly, this high uptake was explained by the slow blood clearance due to non specific aptamer binding to blood proteins. We observed accumulation of radioactivity in both tumours in time. Although higher uptake in the HER2 positive tumour compared to the HER2 negative tumour was observed, this was accompanied with more necrosis in the HER2 negative tumour, which was observed by 18FDG PET/CT. Conclusion: This work presents a first step towards the development of 68Ga labelled aptamers for molecular cancer imaging.