Real-world Afatinib Outcomes in Advanced Non–small Cell Lung Cancer Harboring <i>EGFR</i> Mutations

Afatinib is a standard treatment for patients with advanced non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations. Osimertinib can overcome the treatment resistance-associated EGFR T790M mutation, and the sequence of afatinib followed by osimertinib is an effective therapeutic strategy for NSCLC patients. This study comprehensively evaluated the outcomes of sequential therapy following frontline afatinib and identified predictive factors for T790M mutation acquisition.Data from patients with advanced NSCLC treated with frontline afatinib at a Taiwanese hospital group from June 2014 to March 2018 were retrospectively reviewed. The EGFR T790M mutation was detected by tissue sequencing or liquid biopsy. The patients' clinicopathological features were collected, and univariate and multivariate analyses were performed to identify potential predictive and prognostic factors.A total of 635 patients treated with afatinib were enrolled in this study. Until August 2021, 553 patients experienced progression, and 225 patients underwent T790M mutation testing. The T790M positive rate was 54.2%. Both exon 19 deletion and progression-free survival were associated with T790M positivity. Osimertinib was found to be effective in T790M-positive but not T790M-negative NSCLC. The median overall survival (OS) was 61.8 months for patients with T790M mutation undergoing later-line osimertinib compared with 30.1 months for patients without T790M mutation undergoing chemotherapy only. Osimertinib independently prolonged OS after afatinib progression.This study confirmed the efficacy of sequential afatinib and osimertinib treatment. T790M mutation detection and osimertinib availability are important for prolonging survival in patients with NSCLC harboring EGFR mutations.