Aptamer-based technology for radionuclide targeted imaging and therapy. A promising weapon against cancer

Introduction: aptamers are short artificial, single-strand oligonucleotide sequences (DNA, RNA or modified RNA), capable of binding to biological molecules with high affinity and specificity. Due to their relatively low cost of production and scarce immunogenicity, many efforts have been made to produce aptamers directed against specific molecular targets, such as receptors or transporters overexpressed by malignancies. Areas covered: the technological approaches for generating aptamers are reviewed. Furthermore, the applications of radiolabeled aptamers for the in vivo imaging of several oncological biomarkers through single photon emission computed tomography (SPECT) or positron emission tomography (PET), are covered. Lastly, targeted therapy based on the utilization of aptamers labeled with radionuclides emitting beta particles is discussed, with particular emphasis to the oncological perspectives. Expert opinion: The main limitation of radiolabeled aptamers is represented by their in vivo sensitivity to endogenous nuclease, so that several strategies have been developed to increase the stability of these compounds. Although the applications of aptamers are still in a preliminary and pre-clinical phase, it is reasonable to hypothesize that this technology will play a major role for personalized medicine in the next years.