P3.02b-019 TTF-1 Expression as a Predictor of Response to EGFR-TKIs in Patients with Lung Adenocarcinoma: Topic: EGFR Biomarkers

Abstract

Several studies have shown that overexpression of thyroid transcription factor (TTF-1) may be associated with the presence of epidermal growth factor receptor (EGFR) gene mutations and predict survival in patients with non-small cell lung cancer (NSCLC). Nevertheless, the potential significance of TTF-1 immunostaining as a predictor of response to EGFR tyrosine kinase inhibitors (TKIs) has received limited research attention thus far. The aim of this study was to further explore the potential association between TTF-1 immunohistochemical expression and response to EGFR TKIs in patients with lung adenocarcinoma. The medical records of 129 patients with stage IV lung adenocarcinoma, treated at the Oncology Unit of “Sotiria” Athens General Hospital between January 2011 and December 2014, were retrospectively reviewed. All patients had received treatment with EGFR TKIs (erlotinib or gefitinib) and had a known TTF-1 immunohistochemical expression status in formalin-fixed, paraffin-embedded tumor tissue. Demographic and clinicopathological features (age, gender, smoking status and performance status), TTF-1 immunohistochemistry and EGFR mutation status results were correlated to each other as well as with the response rate (RR) to EGFR TKIs, using univariate and multivariate regression analysis. Median age of our study population was 68 years (range 26-88 years), while the majority were male (79/129 cases, 61.2%). Patients with EGFR mutant tumors had significantly higher response rates to EGFR TKIs compared to patients with wild-type EGFR tumors (p=0.001). TTF-1 positive staining was weakly associated with the presence of EGFR mutations, without reaching the level of statistical significance (p=0.053). Most importantly, TTF-1 positive staining was not significantly correlated with RR to EGFR TKIs, when gender, age, smoking status, EGFR mutation status and PS were included in the multivariate model. The present results failed to demonstrate any independent association between TTF-1 overexpression and the RR to EGFR TKIs in patients with advanced-stage lung adenocarcinoma. Prospective data from larger cohorts of patients are needed to clarify the exact predictive value of TTF-1 immunostaining in this setting.