Biomarker Analyses from a Randomized, Placebo-Controlled, Phase IIIb Trial Comparing Bevacizumab with or without Erlotinib as Maintenance Therapy for the Treatment of Advanced Non-Small-Cell Lung Cancer (ATLAS)

Abstract

ATLAS compared bevacizumab plus erlotinib (B+E) with bevacizumab plus placebo (B+P) as maintenance therapy after first-line bevacizumab plus chemotherapy (B+C) for advanced non-small-cell lung cancer (NSCLC). Prespecified biomarkers were prospectively evaluated. Tumor samples were analyzed for: epidermal growth factor receptor (EGFR) expression (immunohistochemistry [IHC]); EGFR gene copy number (fluorescence in-situ hybridization [FISH]); EGFR mutations (exon 19 deletions/L858R mutations); and KRAS mutations (exons 2/3). Progression-free survival (PFS) and overall survival (OS) were estimated. Of 743 patients randomized to receive maintenance treatment (after four cycles of B+C without progression), 190 (B+E) and 177 (B+P) were evaluable for biomarker status. Median PFS (from randomization) was 4.4 months (B+E) versus 3.7 months (B+P; hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.57-0.99), which was numerically similar to the intent-to-treat PFS. PFS benefit of B+E was observed across most biomarker subgroups. EGFR IHC, EGFR FISH, and EGFR/KRAS mutation status were not predictive of outcome. B+E-treated patients with EGFR mutation-positive NSCLC had longer PFS compared with B+P-treated patients (HR, 0.44; 95% CI, 0.22-0.86; p = 0.0139). Patients with KRAS wild-type disease had significant PFS improvements with B+E, compared with B+P (HR, 0.66; 95% CI, 0.485-0.914; p = 0.0105). No OS benefit of B+E was observed. Patients with KRAS wild-type or EGFR mutation-positive NSCLC derived PFS benefits from B+E. However, EGFR IHC, EGFR FISH, and EGFR or KRAS mutation status were not strongly predictive of survival. A larger sample size would be needed to confirm the initial trends observed in this study.