Lung adenocarcinoma harboring L858R and T790M mutations in epidermal growth factor receptor, with poor response to gefitinib: A case report

Lung cancer is the leading cause of mortality among malignant diseases in humans worldwide. During the last decade, molecular targeted therapies for non-small cell lung cancer using first-generation, reversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), including gefitinib, have been shown to be a promising approach for patients harboring activating mutations in EGFR. The current study reports a 77-year-old patient diagnosed with adenocarcinoma harboring L858R and T790M point mutations in the EGFR gene. The patient was treated with gefitinib as the second-line therapy, but no clinical benefit was observed. As the majority of patients with lung cancer receiving EGFR-TKI therapy acquire resistance, repeated biopsies and detection of the EGFR mutation state are beneficial for selecting appropriate treatments.