KRAS and colorectal cancer: A total of 211 advanced colorectal cancer patients were enrolled in a phase II study, and were divided into 3 arms(arm A: EZN-2208, for KRAS-mutant patients; arm B: EZN-2208+cetuximab, for KRAS-wild-type patients; arm C: irinotecan+cetuximab, for KRAS-Wild type patients).