Inclusion Criteria:

- Man or woman at least 18 years old

- Diagnosis of metastatic colorectal cancer

- One and only one chemotherapy regimen for mCRC consisting of first-line 5-FU -based
chemotherapy

- Radiologically documented disease progression per modified RECIST criteria during
treatment or within 6 months of last dose of first-line chemotherapy

- At least 1 uni-dimensionally measurable lesion of at least 20 mm per modified RECIST

- ECOG status of 0, 1, or 2

- Paraffin-embedded tumor tissue from the primary tumor or metastasis available for
central analyses

- Adequate hematologic, renal, and hepatic functions

- Negative pregnancy test within 72 hours of enrollment

- Other protocol-specified criteria may apply

Exclusion Criteria:

- History of or known presence of CNS metastases

- History of another primary cancer within 5 years of randomization

- Prior irinotecan therapy

- Prior anti-EGFr antibody therapy or treatment with small molecule EGFr inhibitors

- Any investigational agent or therapy within 30 days before randomization

- Known allergy or hypersensitivity to irinotecan, 5-FU or leucovorin

- History of interstitial lung disease or evidence of interstitial lung disease on
baseline chest CT scan

- Active inflammatory bowel disease or other bowel disease causing chronic diarrhea

- Known positive tests for HIV, HCV, acute or chronic active HBV

- Major surgery within 28 days of randomization or minor surgical procedure within 14
days of randomization

- Pregnant or breast-feeding

- Man or woman of child-bearing potential not consenting to use adequate contraceptive
methods or abstinence during the course of the study and for 6 months after last
study drug administration (women) or 1 month after last study drug administration
(men)

- Other protocol-specified criteria may apply