Osimertinib and 6-Thio-dG combination eliminates DTCs and regresses different EGFRm PDX tumors with long-term remissions. (A) Detection of baseline hTERT expression in the indicated EGFRm NSCLC cell lines with primary osimertinib resistance by western blotting. (B and C) The given cell lines were exposed to varied concentrations of osimertinib (Osim), 6-Thio-dG (Thio) alone, or their combination. After 3 days, cell numbers were determined with the SRB assay (B). The data are means ± SDs of four replicate determinations. CIs for the combinations were also calculated (C). (D) The indicated cell lines seeded in 12-well plates were treated with 50 nM osimertinib, 50 nM 6-Thio-dG, or their combination; these treatments were repeated with fresh medium every 2 days. After 5 or 10 days, the cells were fixed, stained with crystal violet dye, and pictured. (E–G) The indicated PDXs in nude mice (six tumors/group) were treated with vehicle, 5 mg/kg osimertinib (daily, og), 2.5 mg/kg 6-Thio-dG (daily, ip), or their combination. The data are means ± SEs of six tumors. Source data are available for this figure: SourceData F7.