Predictive significance of thyroid transcription factor-1 expression in patients with non-squamous non-small cell lung cancer with wild-type epidermal growth factor receptor treated with erlotinib

Little is known on the efficacy of erlotinib treatment in patients expressing wild-type epidermal growth factor receptor (EGFR). This study is a retrospective review of patients with non-squamous, non-small-cell lung cancer (NS-NSCLC) and wild-type EGFR who were treated with erlotinib alone as second- or later-line chemotherapy at the Tokyo Metropolitan Cancer and Infectious Diseases Center of Komagome Hospital (Tokyo, Japan) between December, 2008 and December, 2013. Thyroid transcription factor-1 (TTF-1) was immunohistochemically analyzed in 26 of 53 patients, among whom 20 (77%) and 6 (23%) were considered as TTF-1-positive and -negative, respectively. The median follow-up of these 26 patients was 133 days (range, 26-873 days). The time-to-treatment failure was significantly longer in TTF-1-positive compared with that in TTF-1-negative patients [49.5 vs. 20.0 days; 95% confidence interval (CI): 28-90 vs. 14-74 days, respectively; P=0.01]. The overall survival was significantly better for TTF-1-positive (227 days; 95% CI: 110-366 days) compared with TTF-1-negative patients (P=0.0002). Therefore, the expression of TTF-1 may serve as a useful tool for predicting the efficacy of erlotinib in patients with NS-NSCLC expressing wild-type EGFR.