Tumor‐Selective Gene Therapy: Using Hairpin DNA Oligonucleotides to Trigger Cleavage of Target RNA by Endogenous flap endonuclease 1 (FEN 1) Highly Expressed in Tumor Cells

) and B-cell lymphoma 2 (Bcl-2) genes as targets, it is verified that the hairpin DNA oligonucleotides show cytotoxicity only to tumor cells but very low effects on normal cells. In addition, hairpin DNA oligonucleotides designed for KRAS inhibition, which are encapsulated in lipid nanoparticles, inhibit tumor growth in mice and demonstrate excellent antitumor efficacy in combination with gefitinib, but has little effect on normal tissues, suggesting that the proposed strategy enables highly selective tumor therapy and has the potential to give rise to a new class of nucleic acid drugs.