Abstract
BACKGROUND: Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are the standard treatment for patients with non-small cell lung cancer (NSCLC) harboring EGFR mutations. This study aimed to evaluate the efficacy of EGFR-TKIs and prognostic factors for patients with NSCLC harboring uncommon EGFR mutations, which account for 10% of EGFR mutations. METHODS: A total of 230 treatment-naive patients with NSCLC harboring uncommon EGFR mutations treated with first-line EGFR-TKIs between 2011 and 2018 at four hospitals (belonging to four institutions, Linkou, Kaohsiung, Keelung, and Chiayi, of the Chang Gung Memorial Hospital) in Taiwan were retrospectively reviewed. Their clinicopathological characteristics, adverse events (AEs), objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) were collected. Univariate and multivariate analyses were performed to identify potential prognostic factors for PFS. RESULTS: Overall, patients who received afatinib (n = 62) had better PFS (median: 6.4 vs. 5.9 months, p = 0.022) and OS (median: 13.4 vs. 13.0 months, p = 0.008) than those who received gefitinib/erlotinib (n = 124), although no significant differences were observed for ORR (46.8% vs. 35.5%, p = 0.137) or DCR (59.7% vs. 58.9%, p = 0.916). Patients who received afatinib showed significantly higher ORR (58.3% vs. 31.3%, p = 0.027) but not DCR compared with gefitinib/erlotinib for major uncommon mutations. Afatinib trended toward better PFS and OS for major uncommon mutations and compound mutations. No EGFR-TKIs were effective for most NSCLC patients with exon 20 insertions. Performance status, metastasis of the liver and pleura, and dose reduction were independent prognostic factors for PFS. CONCLUSION: Afatinib demonstrated better survival outcomes than gefitinib/erlotinib for NSCLC patients harboring major EGFR uncommon mutations and compound mutations. Performance status and metastatic sites may be useful for predicting PFS for major uncommon mutations and compound mutations.