Serum biomarkers as potential predictors of antitumor activity of cetuximab-containing therapy for locally advanced head and neck cancer

Abstract

We sought to identify biomarkers of antitumor activity in patients with locally advanced head and neck cancer treated with therapy containing cetuximab, an epidermal growth factor receptor (EGFR) inhibitor. Patients with stage III-IVB head and neck cancer received cisplatin, docetaxel, and cetuximab (TPE) followed by radiotherapy, cisplatin, and cetuximab (XPE) and maintenance cetuximab in a phase II clinical trial. Serum and tissue biomarkers were examined for treatment-related changes and for association with clinical outcomes. Concentrations of 31 cytokines, chemokines and growth factors were measured before and after 3 cycles (9 weeks) of induction TPE using multi-analyte immunobead-based profiling (Luminex Corp., Austin, TX), with selected analytes validated by a single analyte enzyme-linked immunosorbent assay. Tumor biomarkers included phosphorylated signal transducer and activator of transcription-3 (pSTAT3), EGFR and human papillomavirus (HPV). Thirty-one patients had baseline biomarkers and 25 had paired samples, pre- and post-TPE. Adjusting for false discovery, 14 analytes including MCP1c, IP-10, Leptin, interleukin (IL)-5, Eotaxin, IL-6, G-CSF, CXCL5 changed significantly post TPE induction. Serum vascular endothelial growth factor (VEGF) and IL-6 levels were associated with tumor response as assessed by positron emission tomography and progression-free survival, however, the association was not significant after adjustment for false discovery. Analytes were not associated with toxicities, smoking history, HPV status, EGFR amplification, or pSTAT3 tumor protein levels. Baseline serum biomarkers, in particular VEGF and IL-6, were identified as potentially useful prognostic markers of cetuximab-containing therapy. Validation is warranted in future studies specifically designed to detect biomarker associations.

FIGURE 1

Luminex™ validation by single-analyte ELISA. To investigate the reliability of the screening multiplex (Luminex™) assays, individual ELISA assays were performed for VEGF and IL-6, using the same sera as for Luminex. Luminex™ results were highly correlated with single analyte ELISA for VEGF, and moderately correlated with IL-6. In addition, VEGF and IL-6 levels were highly correlated with each other in individual patients’ sera (p<0.001, Spearman correlation coefficient 0.832).

FIGURE 2

Box and whisker plots of VEGF, IL-6 and IP10 by PET response. The concentration levels of each analyte were compared for patients with and without a complete response (CR) by PET. P values for a two-tailed Wilcoxon test are shown above each plot.