Myc Gene Copy Number (Gcn) And Sensitivity To Anti-Egfr Monoclonal Antibodies In Metastatic Colorectal Cancer (Mcrc)

e21018 Background: Monoclonal antibodies against Epidermal Growth Factor Receptor (EGFR) demonstrated efficacy in mCRC patients without mutations in the KRAS gene. Previous data in breast and lung cancer suggested that MYC GCN affects sensitivity to anti-EGFR agents. Methods: This retrospective study was conducted in a cohort of 303 mCRC patients treated with cetuximab/panitumumab, either alone (N=24) or in combination with chemotherapy (N=279). MYC GCN was assessed by fluorescence in situ hybridization (FISH) in primary colorectal cancer tissue samples. Results: In the study population response rate (RR) was 28%, median progression-free survival (PFS) 5.6 months and median overall survival (OS) 11.8 months. MYC was successfully evaluated in 298 cases and was amplified in 17 patients (5.7%). Individuals with MYC amplification showed a trend for a lower RR (7.7% versus 28.9%, p=0.12), shorter PFS (3.0 months versus 5.8 months, p=0.22) and shorter OS (11.3 months versus 12.6 months, p=0.15) than patients wi...