Co-occurring MET Amplification Predicts Inferior Clinical Response to First-Line Erlotinib in Advanced Stage EGFR-Mutated NSCLC Patients.

Clement, Michelle S; Ebert, Eva Boysen Fynboe; Meldgaard, Peter; Sorensen, Boe S

BACKGROUND Intrinsic resistance is a major obstacle in treatment of non-small cell lung cancer (NSCLC) patients with an activating mutation in the epidermal growth factor receptor (EGFR). We investigated co-occurring genetic alterations in circulating tumor DNA (ctDNA) as predictive markers of clinical response to first-line erlotinib. METHODS Pretreatment plasma samples were collected from 76 patients with EGFR-mutated, advanced-stage NSCLC treated with first-line erlotinib. We isolated ctDNA from plasma for next-generation sequencing. RESULTS Co-occurring oncogenic drivers were detected in 21% of pretreatment samples and correlated with decreased progression-free survival (PFS) (6.9 months vs 14.4 months; hazard ratio [HR], 2.088; 95% confidence interval [CI], 0.8119-5.370; P = .0355). Concurrent MET amplification was identified in 9 samples (12%), predicting inferior PFS (5.5 months vs 14.4 months; HR, 4.750; 95% CI, 0.5923-38.10; P = .0007) and overall survival (7.6 months vs 28.3 months; HR, 3.952; 95% CI, 0.8441-18.50; P = .0005). Co-occurring non-MET-amplification oncogenic alterations showed a tendency for shorter PFS (9.9 months vs 14.4 months; HR, 1.199; 95% CI, 0.3373-4.265; P = .7586). Clearing EGFR-mutated ctDNA during erlotinib treatment is a positive predictor of clinical outcomes. Among patients who cleared the EGFR mutation, 12% had a co-occurring oncogenic driver, with a tendency toward inferior PFS (8.7 months vs 16.1 months; HR, 1.703; 95% CI, 0.5347-5.424; P = .2508). CONCLUSION Co-occurring MET amplification in pretreatment ctDNA samples predict inferior clinical response to first-line erlotinib in advanced-stage, EGFR-mutated NSCLC patients. Co-occurring oncogenic alterations were associated with inferior response and may be potential predictors of clinical outcome.