Inclusion Criteria:

- Histologically confirmed adenocarcinoma of the colon or rectum in patients who are
presenting with metastatic disease

- One and only one prior chemotherapy regimen for metastatic disease consisting of the
combination of a fluoropyrimidine-based chemotherapy and an oxaliplatin-based
chemotherapy. Prior adjuvant chemotherapy used prior to the onset of metastatic
disease is permitted

- At least one uni dimensionally measurable lesion per modified RECIST criteria. All
sites of disease must be evaluated <= 28 days before randomization

- Radiographically documented disease progression per modified RECIST criteria either
while receiving or <= 6 months after the last dose of prior chemotherapy regimen for
metastatic disease

- ECOG performance status of 0 or 1

- Man or woman >= 18 years of age

- Adequate end organ assessments by laboratory studies (hematological and chemistries)

- Life expectancy >= 3 months

Exclusion Criteria:

- Exclude subjects with a history of prior malignancy, except:

- 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
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

- Prior irinotecan therapy

- Systemic chemotherapy, hormonal therapy, or immunotherapy <= 21 days prior to
randomization

- Experimental or approved proteins/antibodies (eg, bevacizumab) <= 30 days prior to
randomization

- Clinically significant cardiac disease within 12 months prior to randomization,
including myocardial infarction, unstable angina, grade 2 or greater peripheral
vascular disease, cerebrovascular accident, transient ischemic attack, congestive
heart failure, or arrhythmias not controlled by outpatient medication, percutaneous
transluminal coronary angioplasty/stent

- Known allergy or hypersensitivity to irinotecan, 5 FU (known dihydropyrimidine
dehydrogenase deficiency) or leucovorin

- Active inflammatory bowel disease or other bowel disease causing chronic diarrhea
(defined as >= CTC grade 2 [CTCAE version 3.0])