Abstract 656: DNA repair-interfering molecule AsiDNA® overcomes resistance to tyrosine kinase inhibitors in lung cancer

Abstract Purpose: Drug-tolerance has emerged as one of the major non-genetic mechanism that drives resistance to targeted therapies in lung cancers. Identification of drug-tolerant cells (DTC) vulnerabilities thus represents an attractive strategy to prevent relapse in patients. We observed that EGFR-TKI-derived DTC displayed an increased level of DNA Double Strand Breaks (DSB), raising the hypothesis that genomic instability in these cells could favor the onset of resistance mechanisms. We tested AsiDNA, a small molecule that interferes with the DNA repair machinery, to prevent the emergence of resistances Experimental design: AsiDNA is a double stranded DNA molecule (decoy oligonucleotide) that mimics DNA DSB to interfere with DNA repair, by over-activating a false signaling of DNA damage through DNA-PK and PARP enzymes. We used EGFR-mutated (PC9 and HCC827) or ALK-translocated (H3122) lung tumor cells as well as a PC9 xenograft model, to assess whether a long-term combination of AsiDNA and TKI (erlotinib or osimertinib for EGFR-mutated and alectinib for ALK-translocated cells) could prevent the emergence of resistances arising from DTC. We also performed RNAseq to identify molecular mechanisms underlying AsiDNA effect on TKI-derived DTC. Results:Concomitant treatment of TKI with AsiDNA strongly prevented the emergence of TKI-resistant clones in the three cell lines tested, whereas AsiDNA alone did not display cytotoxic activity. Interestingly, AsiDNA didn’t increase the apoptotic activity of TKI but rather prevented the re-entry of drug-tolerant “dormant” cells into a proliferative state, ultimately resulting in DTC death. RNAseq data revealed a strong downregulation of gene signatures associated with cell cycle, DNA repair but also several pathways known to promote DTC survival such as Epithelial-to-Mesenchymal Transition (EMT) or Interferon pathway in AsiDNA+osimertinib vs osimertinib alone. In vivo, AsiDNA strongly interfered with the emergence of resistances in a PC9 xenograft model treated with erlotinib, resulting in a delayed relapse for the majority of tumors and a complete tumor regression for 20% of them, with no evidence of toxicity for mice. Conclusion: Inhibition of the DNA repair machinery using AsiDNA efficiently prevented the emergence of resistances to tyrosine kinase inhibitors and point to the therapeutic opportunity of combining AsiDNA and TKI to overcome resistance in clinical situation. These findings should have immediate implications to design drug combination strategies to prevent TKI-induced resistance in lung cancers. Citation Format: Sarah Figarol, Sandra Pagano, Wael Jdey, Hugo Guillaume, Gilles Favre, Olivier Calvayrac. DNA repair-interfering molecule AsiDNA® overcomes resistance to tyrosine kinase inhibitors in lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 656.