Gefitinib or Docetaxel as Second Line Therapy for Wild-type Epidermal Growth Factor Receptor (EGFR) NSCLC

Overview

Gefitinib, the first EGFR-tyrosine kinase inhibitor (TKI) in the world was examined as monotherapy in two phase Ⅱ studies called IDEAL trials. Response rate with doses of 250mg and 500mg/day were similar, ranging from 10% to 18%. Posterior analysis demonstrated that patients with EGFR mutation had an improved response rate (RR) to gefitinib compared to wild-type patients (46% versus 10%). The early trials that evaluated EGFR-TKIs for the second- and third-line settings of advanced NSCLC did not select patients on the basis of any EGFR marker. The IEESSA Survival Evaluation in Lung Cancer (ISEL) trial evaluated the role of second-line gefitinib 250mg/day in 1692 patients with advanced NSCLC. Patients with EGFR mutations had higher RR than patients without (37.5% versus 2.6%). From the above results, the response rate in patients without EGFR gene mutation was obviously different (10% versus 2.6%). The methods used for detecting EGFR gene mutation was different, which might contribute to the difference of response rates. In IDEAL trial, EGFR gene mutation was detected by sequencing. But in ISEL trial, EGFR gene mutation was detected by ARMS. As we know, ARMS was more sensitive than sequencing in detecting EGFR gene mutation. That is to say, in IDEAL trials some EGFR mutant patients were misdiagnosed as wild-type patients, so the response rate was higher. Recently, Wu Yi-Long et al reported that relative abundance of EGFR mutations predicted benefit form gefitinib treatment for advanced non small cell lung cancer. The study cohort was all Chinese. In this study, the objective response rate in patients without EGFR mutation detected by ARMS was 16.1%, which was significantly higher than the response rate of docetaxel. But in 2012 American society of clinical oncology (ASCO) annual meeting, the Tailor study in which Italian NSCLC patients were enrolled demonstrated a clear superiority of docetaxel over erlotinib as second line treatment for patients without EGFR mutations in exons 19 or 21. So we wonder if the racial difference is the determinant factor. So the purpose of this trial is to compare the efficacy and safety of gefitinib with docetaxel as second-line therapy for advanced or metastatic Chinese NSCLC patients with wild-type EGFR.

The adoption of docetaxel as a standard second line therapy was based on data from two phase Ⅲ trials. In the first trail, docetaxel (75mg/m2, every 3 weeks) significantly prolonged median and 1-year survival duration compared with best supportive care (median survival, 7.5 months versus 4.6 months; P=0.010; 1-year survival, 37% versus 12%), although the response rate was low (5.5%). In the second study the 6-months and median survival rates were similar for docetaxel and vinorelbine or ifosfamide. However, the 1-year survival rate was significantly greater with docetaxel than ifosfamide or vinorelbine (32% versus 19%, P=0.025). In both studies docetaxel significantly improved some parameters of quality of life. Since these two pivotal studies, new potential second-line drugs were compared with the docetaxel standard of care. With regards to the therapeutic results of the docetaxel arm of these studies, it must be emphasized that response rates and survival data were highly and significantly reproducible.