Anlotinib combined with gefitinib can significantly improve the proliferation of epidermal growth factor receptor-mutant advanced non-small cell lung cancer in vitro and in vivo

Background: The effect of anlotinib combined with epidermal growth factor receptor TKIs (EGFR-TKIs) in patients with advanced non-small cell lung cancer (NSCLC) with acquired resistance to EGFR-TKIs and the possible molecular mechanisms are still unclear. Methods: From April 2018 to June 2020, 20 patients with advanced NSCLC who had developed potential acquired drug resistance after receiving gefitinib or icotinib were enrolled. Anlotinib (12 mg orally, once a day) was added to the targeted drug at the original dose. Patients underwent computed tomography every 8 weeks, and the curative effect and related side effects were observed. Furthermore, in vitro experiments were performed to study the effect of anlotinib alone or in combination with gefitinib on the proliferation and clone-forming ability of NSCLC cells (A549 cells: EGFR wild-type; H1975 cells: with L858R and T790M mutations). Immunohistochemistry was used to detect the expression of related proteins (Ki-67, CD31, EGFR, P-EGFR, VEGFR2, and p-VEGFR2). Results: After the administration of anlotinib, 8 patients were in a stable condition and continued to receive treatment, and the best efficacy disease control rate (DCR) was 100%. The median follow-up time was 6.6 months (4.08-8.28 months). The median progression-free survival was 15.7 months (10.19-18.87 months). The levels of the tumor marker (carcinoembryonic antigen) were found to be significantly decreased in seven patients. The main adverse reactions reported after anlotinib administration were hypertension, hand-foot skin reaction, diarrhea, fatigue, oral ulcers, and anorexia. In the in vitro experiment, anlotinib combined with gefitinib significantly inhibited the proliferation and cloning ability of lung cancer cells. In the nude mouse model, this combination treatment significantly inhibited the growth of lung cancer cells. Immunohistochemical results showed that anlotinib combined with gefitinib significantly inhibited the expression of Ki-67, CD31, EGFR, P-EGFR, VEGFR2, and p-VEGFR2 in tumor tissues. Conclusions: Anlotinib combined with gefitinib inhibited the proliferation of EGFR-TKI-resistant NSCLC cells in vitro and tumor angiogenesis in vivo. It also significantly improved the treatment efficacy for some patients, delaying disease progression and improving survival, with only mild side effects. This drug combination is therefore a promising treatment for patients with EGFR-TKI-resistant and potentially secondary drug-resistant advanced NSCLC.