The expression of EGFR by immunohistochemical staining to predict the response of nimotuzumab in esophageal squamous cell carcinoma.

e15046 Background: It has been demonstrated that epithelial growth factor receptor (EGFR) is overexpressed in 30-80% of esophageal cancer (EC). Therefore, the selection of potential population who could benefit from this treatment is of great importance. We analyzed the EGFR expression by immunohistochemical staining in advanced or metastatic esophageal squamous cell carcinoma (ESCC) patients who received combination treatment of nimotuzumab with chemotherapy to explore the correlation of the EGFR protein expression with the clinical response. Methods: The patients enrolled in this study were from a prospective phase II clinical trial of “Nimotuzumab plus paclitaxel and cisplatin as 1st line treatment for esophageal squamous cell cancer: a single centre prospective clinical trial” (NCT01336049). The tumor tissues were obtained from either gastroscopic biopsy or surgical removed mass. The expression of EGFR was detected by standard immunohistochemical stain methods. The high EGFR expression was defined as strong and continuous membrane staining in more than 50% cells. Results: Totally 55 tumor tissues of ESCC patients were analyzed. 18 of 55 (32.7%) were with high EGFR expression while the other 37 cases were with low to moderate EGFR expression. The expression of EGFR had no relation with the sex, age, tumor location, and tumor differentiation. The objective response rate in EGFR high expression group was 55.6% while that in EGFR low to moderate was 54.1% (p=0.6). The median progression-free survival in EGFR high expression group was much shorter than that in EGFR low to moderate expression group (5.9±1.3 months vs 11.0±3.1 months, P=0.047). The median overall survival in EGFR high expression group was also shorter than that in the EGFR low to moderate expression group (9.7±0.5 months vs 21.5±1.5 months, P=0.037). Conclusions: The overexpression of EGFR could not predict the ORR of the combination of nimotuzumab with chemotherapy. But the high expression of EGFR was associated with poor PFS and OS. It implied that EGFR expression might be a predictor of disease prognosis but not a predictor of the outcome of anti-EGFR agent, nimotuzumab, teatment.