Use of ERCC1 and EGFR expression to predict irinotecan efficacy in patients with metastatic colorectal adenocarcinoma.

e14058 Background: Irinotecan (CPT-11) is a potent therapy in advanced colorectal cancer (CRC). EGFR plays an important role in cell proliferation promoting entry of cells into the S-phase. Cells with high EGFR expression are thought to be more sensitive to topoisomerase-I inhibitors which are predominantly active in the S-phase. ERCC1 reflects increased DNA repair in tumor cells with amplified replication. These unstable cells are highly sensitive to topoisomerase-I inhibitors. Furthermore, EGFR increases expression of ERCC1. Previous studies have identified that gene expression of EGFR and ERCC1 are predictive of clinical outcomes in advanced CRC patients treated first-line with a CPT-11 based regimen. Methods: EGFR and ERCC1 gene expression were measured from metastatic tumors (primary tumor tissue was used if metastatic was not available) via RT-PCR extraction of formalin-fixed, paraffin-embedded samples. A total of 36 patients treated with an irinotecan–based regimen for advanced colorectal cancer at...