Anti-EGFR aptamer exhibits direct anti-cancer effects in NSCLC cells harboring EGFR L858R mutations
Non-small cell lung cancer (NSCLC) lung adenocarcinoma (LUAD) is a leading cause of death worldwide. Activating mutations in the tyrosine kinase domain of the oncogene epidermal growth factor receptor (EGFR) are responsible for ~10-50% of all LUAD cases. Although EGFR tyrosine kinase inhibitors (TKIs) have been effective in prolonging NSCLC patient survival and quality of life, acquired resistance mechanisms and disease progression are inevitable. Contemporary second- and third-line treatments, such as immunotherapy, remain ineffective for these patients, presenting a clear and unmet need for alternative or adjuvant therapeutics for the treatment of mutant EGFR positive NSCLC. Here we show that an anti-EGFR aptamer (EGFRapt) decreases viability of NSCLC cell lines harboring the L858R ± T790M mutation in EGFR but not cell lines harboring wild-type or exon 19 deletions. In a humanized xenograft mouse model, EGFRapt decreased tumor burden compared to controls when delivered intratumorally over multiple doses. To elucidate the mechanism by which EGFRapt exerts these effects, we examined kinase-dependent and kinase-independent mechanisms and found that it is cell line dependent, either inhibiting cellular proliferation or inducing cell death. Post hoc transcriptomics analysis comparing EGFRapt to control aptamer or vehicle validated these findings and provided additional mechanistic insights. Overall, these data establish that EGFRapt has direct anti-cancer activity in mutant EGFR positive NSCLC via targetable mechanisms that are independent of existing approaches and provide a foundation for further development of nucleic acid-based therapies that target EGFR. Overall design: H3255, H1975, H820, and A549 cells were seeded at ~10,000 cells/well in a 48-well flat-bottom tissue culture plate 24 h prior to treatment. Cells were treated with 3 µM EGFRapt (MinE07), control apt (extended version of C36), or vehicle (DPBS and Mg2+) for 24 h, after which the cells were washed twice with DPBS and total RNA was extracted using the Monarch® Total RNA Miniprep Kit (NEB, Ipswich, MA). Total RNA was stored at -80°C until sequencing. Illumina NGS was performed on total RNA from three biologically independent experiments by the University of Missouri DNA Genomics Technology Core using NovaSeq technology to provide 100 base paired end (PE) reads.