WCLC: Effect of EGFR Protein and EGFR Gene Copy Number in SQUIRE Trial
Previously, researchers reporting on the SQUIRE study demonstrated that the addition of necitumumab to gemcitabine-cisplatin improved overall survival in patients with stage IV squamous non–small cell lung cancer (NSCLC). Following up on these findings, Fred R. Hirsch, MD, PhD, Professor of Medicine and Pathology at the University of Colorado, presented additional analysis (Abstract ORAL 32.05) of the relationship with epidermal growth factor receptor (EGFR) protein and EGFR gene copy number at the 16th World Conference on Lung Cancer (WCLC) in Denver, Colorado. This conference was hosted by the International Association of the Study of Lung Cancer.
Study Findings
Dr. Hirsch and SQUIRE study colleagues analyzed 982 patients with evaluable immunohistochemistry assay results. The large majority of these patients (95.2%) had tumor samples expressing EGFR protein; only 4.8% had tumors without detectable EGFR protein.
Analysis showed no consistent trend or obvious cut-points for the relationship between either overall survival or progression-free survival with EGFR protein across the range of immunohistochemistry values when comparing treatment arms. Archived tumor tissue with evaluable results for exploratory EGFR fluorescence in situ hybridization analysis was available for 51% of patients.
Of these patients, 208 patients (37.3%) had increased EGFR gene copy number (fluorescence in situ hybridization–positive). The study did observe a trend for greater necitumumab benefit in EGFR fluorescence in situ hybridization–positive patients. Treatment hazard ratios for fluorescence in situ hybridization–positive and –negative patients were 0.70 and 1.02 for overall survival and 0.71 and 1.04 for progression-free survival. However, the interaction of EGFR gene copy number gain with treatment was not statistically significant for either overall survival or progression-free survival.
Dr. Hirsch concluded that the analysis of EGFR protein expression did not identify consistent trends related to efficacy outcomes across the range of immunohistochemistry values. However, EGFR gene copy number gain showed a trend for a more favorable hazard ratio. Both biomarkers, however, and particularly the fluorescence in situ hybridization biomarker, showed sufficient potential trends to be investigated further in future trials.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
