Objective

Ideally, drugs are designed to treat disease and leave healthy material untouched. Whether this is a specific tissue or whole organs, selectivity is critical. Unfortunately, many therapeutic agents have side-effects due to unwanted “off-target” interactions. This is most evident with anti-cancer chemotherapies where non-specific tissue death occurs.  Selectivity of these drugs can be improved using drug delivery vehicles, with nucleic acid aptamers fast emerging as powerful alternatives. A library of ≈10¹⁵ aptamer molecules is systematically enriched for aptamers that bind to disease associated biomarkers on target cells, whilst ignoring the model healthy cells. We have demonstrated that a disease biomarker targeted aptamer can effectively deliver a cytotoxic payload as an aptamer-drug conjugate to the target disease cells and thereby increase its efficacy. Also, the aptamer-drug conjugate has a protective effect upon the non-target healthy cells, by sequestering the drug and preventing it from being taken up by the healthy cells.