Inclusion Criteria:

- Histologically or cytologically confirmed diagnosis of adenocarcinoma of the colon or
rectum, metastatic disease

- Wild-type KRAS tumor status

- Eastern Cooperative Oncology Group (ECOG) score of 0, 1 or 2

- Must have failed a prior regimen containing irinotecan for metastatic disease and a
prior regimen containing oxaliplatin for metastatic disease

- Must have previously received a thymidylate synthase inhibitor (eg, fluorouracil,
capecitabine, raltitrexed, or fluorouracil-uracil) at any point for treatment of
colorectal cancer (CRC)

- Adequate hematologic, renal, hepatic and metabolic function

Exclusion Criteria:

- Symptomatic brain metastases requiring treatment

- Prior anti-epidermal growth factor receptor (EGFr) antibody therapy (eg, panitumumab
or cetuximab) or treatment with small molecule EGFr inhibitors (eg, gefitinib,
erlotinib, lapatinib)

- Antitumor therapy (eg, chemotherapy, hormonal therapy, immunotherapy, antibody
therapy, radiotherapy), or investigational agent or therapy ≤ 30 days before
randomization.

- Clinically significant cardiovascular disease

- Active infection requiring systemic treatment or any uncontrolled infection ≤14 days
prior to randomization