Patients with biopsy-documented adenocarcinoma of the colon or rectum were eligible for participation
in the study if they had received at least two prior regimens of standard chemotherapies, which could have included adjuvant chemotherapy if a tumor had recurred within 6 months after the last administration of this therapy; if they had
either tumor progression within 3 months after the last administration of chemotherapy; or if they had had clinically significant adverse events from standard chemotherapies that precluded the readministration of those therapies. Eligibility also required knowledge of tumor status with regard to KRAS (i.e., wild-type or mutant), as reported
by investigators. Patients were also required to have received chemotherapy with each of the following agents: a fluoropyrimidine, oxaliplatin, irinotecan, bevacizumab, and — for patients with KRAS wild-type tumors — cetuximab or panitumumab. In addition, patients had to be 18 years of age or older; have adequate bone-marrow,liver, and renal function; and have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 (on a scale of 0 to 5, with 0 indicating no symptoms, 1 indicating mild symptoms, and higher numbers indicating increasing degrees of disability).