Influence of mRNA expression of epiregulin and amphiregulin on outcome of patients with metastatic colorectal cancer treated with 5‐FU/LV plus irinotecan or irinotecan plus oxaliplatin as first‐line treatment (FIRE 1‐trial)

Our aim was to investigate the impact of EREG and AREG mRNA expression (by RT-qPCR) in patients with metastatic colorectal cancer (mCRC). In addition, epidermal growth factor receptor (EGFR) expression (by immunohistochemistry) as well as RAS-and PIK3CA-mutations (by pyrosequencing) were assessed. Tumors of 208 mCRC patients receiving 5-fluorouracil/leucovorin plus irinotecan (FUFIRI) or irinotecan plus oxaliplatin (mIROX) within the FIRE-1 trial were analyzed for mutations. Molecular characteristics were correlated with response, progression-free survival (PFS), overall survival (OS). mRNA expression was evaluated using ROC-analysis in 192 tumors (AREG high n = 31 vs. low n = 161; EREG high n = 89 vs. low n = 103). High versus low AREG expression was associated with PFS of 10.0 versus 8.0 months (HR = 0.62, 95% CI: 0.402-0.940, p = 0.03) and OS of 24.6 versus 18.7 months (HR = 0.72, 95% CI: 0.476-1.078, p = 0.11). High versus low EREG expression correlated with prolonged PFS (9.4 vs. 6.8 months, HR = 0.62, 95% CI: 0.460-0.846, p = 0.002) and OS (25.8 vs. 15.5 months, HR = 0.48, 95% CI: 0.351-0.657, p < 0.001). The positive prognostic effect of high EREG expression was confirmed in a multivariate analysis and was neither affected by EGFR expression nor by mutations of RAS- and PIK3CA-genes. EREG expression appears as an independent prognostic marker in patients with mCRC receiving first-line irinotecan-based chemotherapy.