Update of epidermal growth factor receptor-tyrosine kinase inhibitors in non-small-cell lung cancer

Lung cancer is the leading cause of cancer-related death in the world. Prior to the era of targeted therapy, platinum-based doublet chemotherapy was the first-line therapy of choice for patients with metastatic non-small-cell lung cancer (NSCLC). The availability of agents that target epidermal growth factor receptor (EGFR)-tyrosine kinase, as well as inhibitors against anaplastic lymphoma kinase (ALK) gene rearrangement or ROS-1 gene rearrangement product, has provided promising clinical benefits in specific subpopulations of NSCLC. At present, only first-generation EGFR-tyrosine kinase inhibitors (TKIs) (erlotinib and gefitinib) are available for clinical use. Second-generation irreversible EGFR-TKIs, such as afatinib, are still in clinical trials. In current clinical practice, EGFR-TKI is the first-line treatment of choice for metastatic NSCLC patients with tumor EGFR mutation or as salvage therapy in NSCLC patients who received systemic chemotherapy previously. Platinum-based doublet chemotherapy continues to be the standard of care for those treatment-naïve patients with EGFR wild -type tumor or unknown EGFR status. Even though all investigators agree with the use of EGFR-TKI as the first-line treatment in tumor EGFR-mutated patients, only 10-30% of NSCLC patients have mutated EGFR, and there was no obvious survival difference when EGFR-TKIs were used in a second-line setting versus a first-line treatment in EGFR-mutated patients. Thus, the molecular complexity of lung cancer emphasizes the need for optimizing treatment by seeking a more personalized approach to care, including searching for driver oncogenes, managing the emergence of resistance and overcoming that resistance, and optimizing the sequence of treatment. Numerous other novel targeted agents are now in clinical development, including new agents targeting novel pathways and those that may have the potential to overcome the limitations or resistance associated with currently available EGFR-TKIs. In this report, we review the clinical data of EGFR-TKIs as molecular-targeted therapies in NSCLC.