Suppressing c-FOS expression by G-quadruplex ligands inhibits osimertinib-resistant non-small cell lung cancers

Osimertinib is the first-line therapy for patients with non-small cell lung cancer harboring epidermal growth factor receptor-activating alterations. Although osimertinib has been shown to elicit profound patient responses, cancer cells frequently develop additional alterations that sustain their proliferation capacity. This acquired resistance represents a substantial hurdle in precision medicine for patients with lung cancer.The biological and cellular properties of the G-quadruplex ligand BMVC-8C3O and its anticancer activities were evaluated in non-small cell lung carcinomas. In addition, combined treatment with BMVC-8C3O and osimertinib was evaluated for its effects on the growth of osimertinib-resistant tumors in vivo.We demonstrate that BMVC-8C3O effectively suppresses c-FOS expression by stabilizing G-rich sequences located at the c-FOS promoter. The suppression c-FOS expression by BMVC-8C3O increases the sensitivity of acquired resistant cancer cells to osimertinib. Combining BMVC-8C3O and osimertinib has a synergistic effect in inhibiting the growth of acquired resistant cancers both in vitro and in mouse models. The combined inhibitory effect is not limited to BMVC-8C3O, either: several G-quadruplex ligands show varying levels of inhibition activity. We also show that simultaneous inhibition of both the c-FOS and PI3K/AKT pathways by BMVC-8C3O and osimertinib synergistically inhibits the growth of acquired resistant cancer cells.These findings unveil a synthetic lethal strategy to prevent and inhibit epidermal growth factor receptor-altered lung cancers with acquired osimertinib resistance. G-quadruplex ligands have the potential to be integrated into current osimertinib-based treatment regimens.