Engineering a customized nanodrug delivery system at the cellular level for targeted cancer therapy.

Drug administration customized to individual cells could intrinsically address cancer heterogeneity and provide a safe and effective method for delivering personalized treatment. To accomplish this, we developed a smart nanodrug delivery system characterized by cancer cell-targeted drug delivery and intracellular biomarker-responsive drug activation. This system was composed of a long-nicked DNA duplex formed by tandem hybridization of two extended antisense oligonucleotides whose ends were separately blocked with a cancer cell-specific aptamer, AS1411, and a replaceable anti-biomarker probe (ABP). We demonstrated that this DNA nanodrug was directed to cancer cells with the guidance power of AS1411 and then activated by the presence of a given intracellular biomarker. By using such a belt-and-braces strategy, this DNA nanodrug system could safely and efficiently accelerate apoptosis of target cancer cells. Moreover, since the expression level of biomarkers tends to indicate the specific physiological state of individual cells, biomarker-responsive activation of the nanodrug is expected to enable customized drug administration at the cellular level.