Inclusion Criteria:

- Adult patients, >/= 18 years of age

- Histologically or cytologically confirmed adenocarcinoma of the colon and/or rectum,
with KRAS wild-type status

- Progressive disease on or after first-line oxaliplatin-containing regimen for
metastatic colorectal cancer; patients must have received oxaliplatin-containing
chemotherapy for >/= 3 months; no more than one prior chemotherapy for metastatic
disease is allowed

- Measurable disease per RECIST v1.1

- Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1

- Adequate hematologic and end-organ function

Exclusion Criteria:

- Prior treatment with irinotecan

- Prior treatment with an investigational or approved HER-targeted agent

- Last anti-tumor therapy within 4 weeks prior to Cycle 1, Day 1, including
chemotherapy, biologic, experimental, hormonal or radiotherapy, or not having
recovered from all treatment-related toxicities (except for alopecia) to Grade with the following exceptions: oxaliplatin-containing chemotherapy within 2
weeks prior to Cycle 1, Day 1, oxaliplatin-related neuropathy that is Grade considered stable, and palliative radiotherapy to bone metastases within 2 weeks
prior to Cycle 1, Day 1

- Leptomeningeal disease as the only manifestation of the current malignancy

- Active infection requiring IV antibiotics

- Active autoimmune disease that is not controlled by nonsteroidal anti-inflammatory
drugs

- Current severe , uncontrolled systemic disease

- History of cardiac heart failure or serious cardiac arrhythmia requiring treatment
(except for atrial fibrillation and paroxysmal supraventricular tachycardia)

- History of myocardial infarction within 6 months prior to Cycle 1 Day 1, or history
of unstable angina

- Clinically significant GI bleeding within 6 months prior to Cycle 1 Day 1

- History of severe (Grade 3 or 4) allergic or hypersensitivity reaction to therapeutic
antibodies that required discontinuation of treatment

- Known HIV infection

- Untreated CNS metastases (progressing or requiring anticonvulsants or corticosteroids
for symptomatic control)

- Pregnant or lactating women

- Malignancies other than colorectal cancer within 5 years prior to randomization,
except for adequately treated basal or squamous cell skin cancer and carcinoma in
situ of the cervix