Background: Epidermal growth factor receptor (EGFR) exon 20 insertion mutations account for 4%–10% of all EGFR mutations in patients with non-small cell lung cancer (NSCLC). However, data on the differences in clinical characteristics between patients with EGFR exon 20 insertion mutations and major mutations (exon 19 deletion and L858R) are limited.
Methods: We retrospectively reviewed advanced NSCLC patients with EGFR mutations, including EGFR exon 20 insertions and major mutations, who were treated with systemic therapy between January 2011 and December 2019.
Results: We identified 23 patients with EGFR exon 20 insertions and 534 patients with EGFR mutations. Among patients with exon 20 insertion, the median age was 60 years (range: 27–88 years), and females and never smokers were predominant. The clinical characteristics of patients with exon 20 insertions were similar to those with major EGFR mutations. Regarding the clinical outcomes in patients with exon 20 insertions, 17 patients received platinum doublet as first-line therapy, and the overall response rate (ORR) and median progression-free survival (mPFS) were 11.8% and 8.9%. Additionally, eight patients received anti-PD-1 antibodies and seven patients received EGFR-tyrosine kinase inhibitors (TKIs) in any-line therapy, and their ORR and mPFS were 0%, 25% and 2.2, 3.1 months, respectively. Overall survival was significantly shorter in patients with exon 20 insertions than in those with EGFR major mutations (29.3 vs. 43.4 months, p=0.04).
Conclusions: The clinical outcomes in patients with exon 20 insertions were not satisfactory compared to those in patients with major EGFR mutations.