High EGFR copy number predicts benefits from tyrosine kinase inhibitor treatment for non-small cell lung cancer patients with wild-type EGFR.

Background: This study was designed to determine whether advanced non-small-cell lung cancer (NSCLC) patients with high copy number of epidermal growth factor receptor (EGFR) can benefit from treatment with EGFR-tyrosine kinase inhibitors (TKIs).

Methods: EGFR gene copy number was assessed by fluorescence in situ hybridization (FISH) and EGFR mutations was tested using Luminex xTAG technology in 502 TKI-treated NSCLC patients. The association between both biomarkers and clinical benefit from EGFR-TKI were analyzed.

Results: EGFR FISH+and EGFR mutations were significantly associated with higher response rates (37.2% and 43.7%, respectively), superior progression-free survival (PFS) (FISH+, 11.2 months; hazard ratio [HR], 0.51; 95% CI, 0.42 to 0.62; p<0.001; mutation+, 11.7 months; HR, 0.37; 95% CI, 0.31 to 0.45; p<0.001) and overall survival (OS) (FISH+, 30.2 months; HR, 0.51; 95% CI, 0.40 to 0.65; p<0.001; mutation+, 30.2 months; HR, 0.45; 95% CI, 0.36 to 0.58; p<0.001). In patients with wild-type EGFR, EGFR FISH+correlated with longer PFS than EGFR FISH- status (4.4 months vs. 2.0 months; HR, 0.56; 95% CI, 0.41 to 0.75; p<0.001), so did amplification (5.0 months vs. 2.0 months; HR, 0.43; 95% CI, 0.24 to 0.76; p=0.003). However, FISH+had no association with improved PFS in EGFR-mutated patients (HR, 0.77; 95% CI, 0.57 to 1.03; p=0.076).

Conclusions: A combined analysis of EGFR FISH and mutation is an effective predictor of EGFR-TKI therapy. Specifically, a high EGFR copy number may predict benefit from TKIs treatment for NSCLC patients with wild-type EGFR.