The combination of osimertinib with 6-Thio-dG effectively inhibits the growth of osimertinib-resistant EGFRm NSCLC xenografts. HCC27/AR or PC-9/AR cells grown in NU/NU nude mice as xenografted tumors (n = 6/group) were treated with vehicle, osimertinib alone (5 mg/kg, daily, oral gavage [og]), 6-Thio-dG (Thio) alone (2.5 mg/kg/day, daily, intraperitoneal injection [ip]), or their combination. (A) Tumor sizes were measured at the indicated time points (A). (B and C) At the end of treatment, tumors in each group were also weighed (B) and photographed (C). The data in each group are means ± SEs of six tumors from six mice. (D) The proteins of interest as indicated were stained with IHC (D). Statistical analysis was conducted with one-way ANOVA test.