Introduction:In the phase IV, open-label, single-arm study NCT01203917, first-line gefitinib 250 mg/d was effective and well tolerated in Caucasian patients with epidermal growth factor receptor (EGFR) mutation-positive non–small-cell lung cancer (previously published). Here, we report EGFR mutation analyses of plasma-derived, circulating-free tumor DNA.Methods:Mandatory tumor and duplicate plasma (1 and 2) baseline samples were collected (all screened patients; n = 1060). Preplanned, exploratory analyses included EGFR mutation (and subtype) status of tumor versus plasma and between plasma samples. Post hoc, exploratory analyses included efficacy by tumor and plasma EGFR mutation (and subtype) status.Results:Available baseline tumor samples were 1033 of 1060 (118 positive of 859 mutation status known; mutation frequency, 13.7%). Available plasma 1 samples were 803 of 1060 (82 positive of 784 mutation status known; mutation frequency, 10.5%). Mutation status concordance between 652 matched tumor and plasma 1 samples was 94.3% (95% confidence interval [CI], 92.3–96.0) (comparable for mutation subtypes); test sensitivity was 65.7% (95% CI, 55.8–74.7); and test specificity was 99.8% (95% CI, 99.0–100.0). Twelve patients of unknown tumor mutation status were subsequently identified as plasma mutation-positive. Available plasma 2 samples were 803 of 1060 (65 positive of 224 mutation status-evaluable and -known). Mutation status concordance between 224 matched duplicate plasma 1 and 2 samples was 96.9% (95% CI, 93.7–98.7). Objective response rates are as follows: mutation-positive tumor, 70% (95% CI, 60.5–77.7); mutation-positive tumor and plasma 1, 76.9% (95% CI, 65.4–85.5); and mutation-positive tumor and mutation-negative plasma 1, 59.5% (95% CI, 43.5–73.7). Median progression-free survival (months) was 9.7 (95% CI, 8.5–11.0; 61 events) for mutation-positive tumor and 10.2 (95% CI, 8.5–12.5; 36 events) for mutation-positive tumor and plasma 1.Conclusion:The high concordance, specificity, and sensitivity demonstrate that EGFR mutation status can be accurately assessed using circulating-free tumor DNA. Although encouraging and suggesting that plasma is a suitable substitute for mutation analysis, tumor tissue should remain the preferred sample type when available.

Selumetinib (AZD6244, ARRY-142886) is a selective, non–ATP-competitive inhibitor of mitogen-activated protein/extracellular signal–regulated kinase kinase (MEK)-1/2. The range of antitumor activity seen preclinically and in patients highlights the importance of identifying determinants of response to this drug. In large tumor cell panels of diverse lineage, we show that MEK inhibitor response does not have an absolute correlation with mutational or phospho-protein markers of BRAF/MEK, RAS, or phosphoinositide 3-kinase (PI3K) activity. We aimed to enhance predictivity by measuring pathway output through coregulated gene networks displaying differential mRNA expression exclusive to resistant cell subsets and correlated to mutational or dynamic pathway activity. We discovered an 18-gene signature enabling measurement of MEK functional output independent of tumor genotype. Where the MEK pathway is activated but the cells remain resistant to selumetinib, we identified a 13-gene signature that implicates the existence of compensatory signaling from RAS effectors other than PI3K. The ability of these signatures to stratify samples according to functional activation of MEK and/or selumetinib sensitivity was shown in multiple independent melanoma, colon, breast, and lung tumor cell lines and in xenograft models. Furthermore, we were able to measure these signatures in fixed archival melanoma tumor samples using a single RT-qPCR–based test and found intergene correlations and associations with genetic markers of pathway activity to be preserved. These signatures offer useful tools for the study of MEK biology and clinical application of MEK inhibitors, and the novel approaches taken may benefit other targeted therapies.

Background:Phase-IV, open-label, single-arm study (NCT01203917) to assess efficacy and safety/tolerability of first-line gefitinib in Caucasian patients with stage IIIA/B/IV, epidermal growth factor receptor (EGFR) mutation-positive non-small-cell lung cancer (NSCLC).Methods:Treatment: gefitinib 250 mg day−1 until progression. Primary endpoint: objective response rate (ORR). Secondary endpoints: disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and safety/tolerability. Pre-planned exploratory objective: EGFR mutation analysis in matched tumour and plasma samples.Results:Of 1060 screened patients with NSCLC (859 known mutation status; 118 positive, mutation frequency 14%), 106 with EGFR sensitising mutations were enrolled (female 70.8% adenocarcinoma 97.2% never-smoker 64.2%). At data cutoff: ORR 69.8% (95% confidence interval (CI) 60.5–77.7), DCR 90.6% (95% CI 83.5–94.8), median PFS 9.7 months (95% CI 8.5–11.0), median OS 19.2 months (95% CI 17.0–NC; 27% maturity). Most common adverse events (AEs; any grade): rash (44.9%), diarrhoea (30.8%); CTC (Common Toxicity Criteria) grade 3/4 AEs: 15% SAEs: 19%. Baseline plasma 1 samples were available in 803 patients (784 known mutation status; 82 positive; mutation frequency 10%). Plasma 1 EGFR mutation test sensitivity: 65.7% (95% CI 55.8–74.7).Conclusion:First-line gefitinib was effective and well tolerated in Caucasian patients with EGFR mutation-positive NSCLC. Plasma samples could be considered for mutation analysis if tumour tissue is unavailable.