Inclusion Criteria:

Histologically or cytologically confirmed metastatic adenocarcinoma of
the colon or rectum; Subjects with wild-type KRAS tumor status confirmed by an Amgen
approved central laboratory assessment or an experienced local laboratory assessment of
archival tumor tissue (preferably from the primary tumor); Radiographic evidence of
disease progression while on or ≤ 6months after completion of treatment with irinotecan-
and oxaliplatin- or oxaliplatin-based chemotherapy for mCRC; Radiographic measurement of
tumor burden done within 28 days prior to Day 1 (start of treatment with investigational
product); At least 1 uni-dimensionally measurable lesion ≥ 20 mm using conventional CT or
MRI or ≥ 10 mm by spiral CT scan per modified RECIST v1.0. Lesion must not be chosen from
a previously irradiated field, unless there has been documented disease progression in
that field after irradiation and prior to enrollment. All sites of disease must be
evaluated; At least 1 tumor (preferably a metastasis or unresected primary tumour) that is
amenable to core biopsy, as determined by the clinician who will perform the biopsy;
Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1; Male or female ≥
18 years of age at the time of informed consent; A life expectancy estimate of ≥ 3 months;
Willing to undergo two serial core biopsy procedures of tumors (metastasis or unresected
primary); other criteria may apply Exclusion Criteria: History of other primary cancer,
unless: Malignancy treated with curative intent and with no known active disease present
for ≥ 3 years before enrollment and felt to be at low risk for recurrence by the treating
physician, Adequately treated non-melanomatous skin cancer or lentigo maligna without
evidence of disease, Adequately treated cervical carcinoma in situ without evidence of
disease, Prostatic intraepithelial neoplasia without evidence of prostate cancer; History
of prior or concurrent central nervous system (CNS) metastases; Prior treatment with
anti-EGFR (eg, panitumumab, cetuximab or small molecule inhibitors (eg, erlotinib,
gefitinib); Prior treatment with monoclonal antibodies directed against insulin-like
growth factor-1 receptor (IGF-1R) or small molecule inhibitors directed against IGF-1R;
Use of systemic chemotherapy or radiotherapy ≤ 21 days before enrollment. Subjects must
have recovered from acute toxicities related to radiotherapy; Use of any antibody therapy
(eg, bevacizumab) ≤ 42 days before enrolment; Use of anti-tumor therapies including prior
experimental agents or approved anti-tumor small molecules ≤ 30 days before enrolment;
Known allergy or hypersensitivity to any component of panitumumab, irinotecan, or AMG 479;
Known uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) polymorphisms predisposing
to increased irinotecan toxicity; History of irinotecan intolerance that may interfere
with planned treatment; History of interstitial lung disease (eg, pneumonitis, pulmonary
fibrosis) or evidence of interstitial lung disease on baseline chest computerized
tomography (CT) scan; Clinically significant cardiovascular disease (including myocardial
infarction, unstable angina, symptomatic congestive heart failure, serious uncontrolled
cardiac arrhythmia) ≤ 1 year before enrolment; Active inflammatory bowel disease or other
active bowel disease causing chronic diarrhea (defined as ≥ grade 2 per Common Terminology
Criteria for Adverse Events (CTCAE) version 3.0); Known positive test(s) for human
immunodeficiency virus (HIV) infection, hepatitis C virus, acute or chronic active
hepatitis B infection; Major surgical procedure ≤ 28 days before enrollment or minor
surgical procedure ≤ 14 days before enrollment. Subjects must have recovered from surgery
related toxicities. Core biopsy, central venous catheter placement, fine needle
aspiration, thoracentesis, or paracentesis is not considered a major or minor surgical
procedure; Other investigational procedures or drugs (ie, participation in another
clinical study) ≤ 30 days before enrolment; other criteria may apply