Increased EGFR gene copy number detected by fluorescent in situ hybridization predicts outcome in non-small-cell lung cancer patients treated with cetuximab and chemotherapy.

Abstract

Epidermal growth factor receptor (EGFR) gene copy number detected by fluorescent in situ hybridization (FISH) has proven to be useful for selection of non-small-cell lung cancer (NSCLC) patients for treatment with EGFR tyrosine kinase inhibitors. Here, we evaluate EGFR FISH as a predictive marker in NSCLC patients receiving the EGFR monoclonal antibody inhibitor cetuximab plus chemotherapy. Two hundred twenty-nine chemotherapy-naive patients with advanced-stage NSCLC were enrolled onto a phase II selection trial evaluating sequential or concurrent chemotherapy (paclitaxel plus carboplatin) with cetuximab. EGFR FISH was assessable in 76 patients with available tumor tissue and classified as positive (four or more gene copies per cell in >/= 40% of the cells or gene amplification) in 59.2%. Response (complete response/partial response) was numerically higher in FISH-positive (45%) versus FISH-negative (26%) patients (P = .14), whereas disease control rate (complete response/partial response plus stable disease) was statistically superior (81% v 55%, respectively; P = .02). Patients with FISH-positive tumors had a median progression-free survival time of 6 months compared with 3 months for FISH-negative patients (P = .0008). Median survival time was 15 months for the FISH-positive group compared with 7 months for patients who were FISH negative. (P = .04). Furthermore, survival favored FISH-positive patients receiving concurrent therapy. These results are the first to suggest that EGFR FISH is a predictive factor for selection of NSCLC patients for cetuximab plus chemotherapy. Prospective validation of these findings is warranted.