PFS was defined as the time from the date of randomization to the date of first disease progression, or death within 60 days after the last evaluable tumor assessment or randomization date (whichever was later). Participants not meeting the criteria by the cutoff date were censored at the last evaluable tumor assessment date. Tumor response was evaluated by the investigator per modified Response Evaluation Criteria in Solid Tumors (RECIST) version 1.0 every 8 weeks until radiographic disease progression. Progression is defined as at least a 20% increase in the size of target lesions, unequivocal progression of existing non-target lesions, or any new lesions.

Intent-to-treat (ITT) analysis set (all randomized participants)

Overall survival was defined as the time from randomization to the date of death, with participants alive or lost to follow-up at the analysis data cutoff date censored at their last contact date.

Intent-to-treat analysis set

Objective response was defined as having a confirmed complete response (CR) or partial response (PR) during first-line treatment, based on the investigator's review of scans using a modified-RECIST v1.0. A complete or partial response was confirmed no less than 4-weeks after the criteria for response were first met. Complete Response: Disappearance of all target and non-target lesions and no new lesions. Partial Response: At least a 30% decrease in the sum of the longest diameter (SLD) of target lesions and no progression of non-target lesions and no new lesions, or the disappearance of all target lesions with persistence of one or more non-target lesion(s) not qualifying for either CR or progressive disease and no new lesions.

Evaluable for Local Tumor Response Analysis Set, defined as the subset of participants in the ITT Analysis Set who had at least 1 unidimensionally measurable lesion per modified RECIST 1.0 per the local investigator.

For participants with a confirmed objective response, the time from first confirmed objective response to radiologic disease progression per modified RECIST 1.0 criteria or death. For participants who responded and have not progressed or died, duration of response was censored at their last evaluable disease assessment date.

Evaluable for Local Tumor Response Analysis Set: Responders

Time to progression (TTP) is defined as the time from randomization to the date of radiologic disease progression per modified RECIST 1.0 criteria. Participants not meeting criteria for disease progression by the analysis data cutoff date were censored at their last evaluable disease assessment date. Progression is defined as at least a 20% increase in the size of target lesions, unequivocal progression of existing non-target lesions, or any new lesions.

Intent-to-treat analysis set

For participants with a confirmed objective response, the time from randomization to the date of first confirmed objective response. Assessments are based on the investigator's review of scans using a modified-RECIST v1.0. An objective response is defined as a best tumor response of complete or partial response. A complete or partial response was confirmed no less than 4-weeks after the criteria for response were first met.

Evaluable for Local Tumor Response Analysis Set: Responders

The resection rate was defined as the percentage of participants with a surgical procedure that resulted in partial reduction or complete eradication of all metastatic disease.

Intent-to-treat analysis set

PFS was defined as the time from the date of randomization to the date of first disease progression, or death within 60 days after the last evaluable tumor assessment or randomization date (whichever was later). Participants not meeting the criteria by the cutoff date were censored at the last evaluable tumor assessment date. Tumor response was evaluated by the investigator per modified Response Evaluation Criteria in Solid Tumors (RECIST) version 1.0 every 8 weeks until radiographic disease progression. Progression is defined as at least a 20% increase in the size of target lesions, unequivocal progression of existing non-target lesions, or any new lesions.

Wild-type RAS Efficacy Analysis Set, defined as a subset of Wild-type KRAS Exon 2 Efficacy Analysis Set including all randomized participants with wild-type KRAS exon 2, 3, 4, NRAS exon 2, 3, and 4.

PFS was defined as the time from the date of randomization to the date of first disease progression, or death within 60 days after the last evaluable tumor assessment or randomization date (whichever was later). Participants not meeting the criteria by the cutoff date were censored at the last evaluable tumor assessment date. Tumor response was evaluated by the investigator per modified Response Evaluation Criteria in Solid Tumors (RECIST) version 1.0 every 8 weeks until radiographic disease progression. Progression is defined as at least a 20% increase in the size of target lesions, unequivocal progression of existing non-target lesions, or any new lesions.

Wild-type RAS/BRAF Efficacy Analysis Set was defined as a subset of Wild-type KRAS Exon 2 Efficacy Analysis Set with wild-type KRAS exon 2, 3, and 4, NRAS exon 2, 3, 4, and BRAF exon 15.

Overall survival was defined as the time from randomization to the date of death, with participants alive or lost to follow-up at the analysis data cutoff date censored at their last contact date.

Wild-type RAS Efficacy Analysis Set, defined as a subset of Wild-type KRAS Exon 2 Efficacy Analysis Set including all randomized participants with wild-type KRAS exon 2, 3, 4, NRAS exon 2, 3, and 4.

Overall survival was defined as the time from randomization to the date of death, with participants alive or lost to follow-up at the analysis data cutoff date censored at their last contact date.

Wild-type RAS/BRAF Efficacy Analysis Set was defined as a subset of Wild-type KRAS Exon 2 Efficacy Analysis Set with wild-type KRAS exon 2, 3, and 4, NRAS exon 2, 3, 4, and BRAF exon 15.

Objective response was defined as having a confirmed complete response (CR) or partial response (PR) during first-line treatment, based on the investigator's review of scans using a modified-RECIST v1.0. A complete or partial response was confirmed no less than 4-weeks after the criteria for response were first met.

Complete Response: Disappearance of all target and non-target lesions and no new lesions. Partial Response: At least a 30% decrease in the sum of the longest diameter (SLD) of target lesions and no progression of non-target lesions and no new lesions, or the disappearance of all target lesions with persistence of one or more non-target lesion(s) not qualifying for either CR or progressive disease and no new lesions.

Wild-type RAS Investigator Tumor Response Analysis Set, defined as the subset of participants in the Wild-type RAS Efficacy Analysis Set who had at least 1 unidimensionally measurable lesion per modified RECIST 1.0 per the local investigator.

Objective response was defined as having a confirmed complete response (CR) or partial response (PR) during first-line treatment, based on the investigator's review of scans using a modified-RECIST v1.0. A complete or partial response was confirmed no less than 4-weeks after the criteria for response were first met. Complete Response: Disappearance of all target and non-target lesions and no new lesions. Partial Response: At least a 30% decrease in the sum of the longest diameter (SLD) of target lesions and no progression of non-target lesions and no new lesions, or the disappearance of all target lesions with persistence of one or more non-target lesion(s) not qualifying for either CR or progressive disease and no new lesions.

Wild-type RAS/BRAF Investigator Tumor Response Analysis Set, defined as the subset of participants in the Wild-type RAS/BRAF Efficacy Analysis Set who had at least 1 unidimensionally measurable lesion per modified RECIST 1.0 per the local investigator.

Severity was graded using Common Terminology Criteria for Adverse Events (CTCAE) v3.0, with the exception of some dermatology/skin adverse events that were graded using CTCAE v3.0 with modifications. Fatal adverse events are classified as grade 5. Serious adverse events include any event that is fatal, life threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, a congenital anomaly/birth defect, or other significant medical hazard. Treatment-related AEs were those that the investigator considered a reasonable possibility that might have been caused by study drug.

Safety analysis set, which included all randomized participants who received at least 1 dose of protocol treatment (ie, panitumumab, bevacizumab, or any component of mFOLFOX6).