The role of anti-EGFR therapies in EGFR-TKI-resistant advanced non-small cell lung cancer

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are the current recommended option for the first-line treatment of patients with EGFR-mutant non-small cell lung cancer (NSCLC). Resistance to first-generation TKIs led to the development of second- and third-generation TKIs with improved clinical outcomes. However, sequential administration of TKIs has led to the emergence of new EGFR resistance mutations and persistent tumor cell survival. This evidence highlights the potential role of EGFR in transducing growth signals in NSCLC tumor cells. Therefore, dual inhibition of EGFR using combinations of anti-EGFR monoclonal antibodies (mAbs) and EGFR-TKIs may offer a unique treatment strategy to suppress tumor cell growth. Several clinical studies have demonstrated the benefits of dual blockade of EGFR using anti-EGFR mAbs coupled with EGFR-TKIs in overcoming treatment resistance in patients with EGFR-mutated NSCLC. However, a single treatment option may not result in the same clinical benefits in all patients with acquired resistance. Biomarkers, including EGFR overexpression, EGFR gene copy number, EGFR and KRAS mutations, and circulating tumor DNA, have been associated with improved clinical efficacy with anti-EGFR mAbs in patients with NSCLC and acquired resistance. Further investigation of biomarkers may allow patient selection for those who could benefit from anti-EGFR mAbs in combination with EGFR-TKIs. This review summarizes findings of recent studies of anti-EGFR mAbs in combination with EGFR-TKIs for the treatment of patients with EGFR-mutated NSCLC, as well as clinical evidence for potential biomarkers towards personalized targeted medicine.