Selection of aptamers targeting a hypoxia marker: Carbonic Anhydrase-IX (CA-IX)

Aptamers are selected by an in vitro combinatorial chemistry approach, named Systematic Evolution of Ligands by Exponential enrichment (SELEX), and they are able to bind with high affinity and specificity virtually any given molecule. Compared to monoclonal antibodies, they have a small size that results in their rapid tumour penetration; they are not immunogenic and could be easily modified to increase their in vivo stability. Thus, in this study we describe the selection of RNA-based aptamers directed against an hypoxic biomarker. Firstly, we performed two different cell-based SELEX protocols that allowed the specific enrichment for the target. Furthermore, we characterized and improved the two best sequences selected, named S-47s1 and S-51s1, that we are still studying to handle a final product usable for diagnostic and therapeutic purposes.