Inclusion Criteria:

1. Patient must have histologically or cytologically confirmed colorectal adenocarcinoma
with metastatic disease documented on diagnostic imaging studies.

2. Patient must have measurable lesions as defined by modified Response Evaluation
Criteria In Solid Tumors (RECIST) criteria. Patients who agree to undergo the
optional Dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) studies must
have a metastatic liver lesion that is > 2 cm.

3. Patient has not previously received chemotherapy for metastatic disease.

4. Patient may have received adjuvant therapy for primary colorectal cancer provided
that at least 6 months have elapsed from the time the adjuvant therapy was concluded
and recurrent disease was documented.

5. Written informed consent obtained.

6. Age greater than/equal to 18 years.

7. Eastern Cooperative Oncology Group (ECOG) performance status 0-2

8. Patients must have adequate organ and marrow function as defined below: · Absolute
neutrophil count (ANC) greater than/equal to 1,500/mm3; platelets greater than/equal
to 100,000/ mm3; hemoglobin greater than/equal to 9 gm/dL (may be transfused to
maintain or exceed this level); total bilirubin less than/equal to 1.5 within
institutional upper limit of normal (IULN); aspartate aminotransferase (AST or
SGOT)/alanine aminotransferase (ALT or SGPT) less than/equal to 2.5 times IULN, or
less than/equal to 5 times IULN if known liver metastases; serum creatinine less
than/equal to 1.5 times IULN

9. Patients must have an International Normalized Ratio (INR) less than/equal to 1.5 and
a Partial thromboplastin time (PTT) less than/equal to IULN

10. Patients with history of hypertension must be well-controlled (blood pressure less
than/equal to 150/100), on a stable regimen of anti-hypertensive therapy.

Exclusion Criteria:

1. Current, recent (within 4 weeks of the first infusion of this study), or planned
participation in an experimental therapeutic drug study other than this protocol.

2. Prior full field radiotherapy less than/equal to 4 weeks or limited field
radiotherapy less than/equal to 2 weeks prior to treatment.

3. History or presence of central nervous system metastases.

4. Female patients who are pregnant or lactating or men and women of reproductive
potential not willing to employ an effective method of birth control during treatment
and for 3 months after discontinuing study treatment.

5. A history of prior treatment with bevacizumab or other agents targeting Vascular
endothelial growth factor (VEGF).

6. Known dihydropyrimidine dehydrogenase deficiency.

7. Patients with a history of allergic reactions attributed to compounds of similar
chemical or biologic composition to bevacizumab, irinotecan, 5-FU, or leucovorin.

8. Serious non-healing wound, ulcer, or active bone fracture.

9. Major surgical procedure, open biopsy or significant traumatic injury within 28 days
prior to Day 0; anticipation of need for major surgical procedure during the course
of the study.

10. Fine needle aspirations or core biopsies within 7days prior to Day 0.

11. For patients who agree to Optional DCE-MRI studies: Cardiac pacemaker,
neurostimulator, metal implants other than those specifically approved as safe for
use in MR scanners at the magnetic field strength used for these studies,
claustrophobia, obesity (weight exceeding equipment limits).

12. Current or recent use of full-dose warfarin (except as required to maintain patency
of preexisting, permanent indwelling IV catheters) for subjects receiving warfarin,
INR should be < 1.5). Patients may have prophylactic use of low molecular weight
heparin, however therapeutic use of heparin or low molecular weight heparin is not
acceptable.

13. Evidence of bleeding diathesis or coagulopathy.

14. Patients with a history of another primary malignancy less than/equal to 5 years,
with the exception of non-melanoma skin cancer, and carcinoma in situ of uterine
cervix.

15. History of abdominal fistula, gastrointestinal perforation, or intra-abdominal
abscess within 6 months prior to Day 0, unless affected area has been removed
surgically.

16. Any of the following concurrent severe and/or uncontrolled medical conditions which
could compromise participation in the study: Uncontrolled high blood pressure,
history of labile hypertension, or history of poor compliance with an
antihypertensive regimen; Unstable angina; New York Heart Association (NYHA) greater
than/equal to grade 2 congestive heart failure

17. Myocardial infarction within 6 months of study enrollment; History of stroke within 6
months of study enrollment; Unstable symptomatic arrhythmia requiring medication
(Patients with chronic atrial arrhythmia, i.e., atrial fibrillation or paroxysmal
supraventricular tachycardia are eligible); Clinically significant peripheral
vascular disease; Uncontrolled diabetes; Serious active or uncontrolled infection

18. History of other disease, metabolic dysfunction, physical examination finding, or
clinical laboratory finding giving reasonable suspicion of a disease or condition
that contraindicates the use of an investigational drug or that might affect the
interpretation of the results of the study or render the subject at high risk from
treatment complications.

19. Inability to comply with study and/or follow-up procedures.