Inclusion Criteria:

- Patients with CEA expressing advanced colorectal tumors for which no standard
treatment is available

- WHO performance status: 0 or 1

- Having normal hematological function: Neutrophils > 1.5 x 109/l; Platelet count > 150
x 109/l, without transfusion during the previous month; Hemoglobin > 5.6 mmol/l

- Total bilirubin < 2 x upper limit of normal (ULN)

- ASAT, ALAT < 3 x ULN

- Serum creatinine < 2 x ULN

- Cockcroft clearance > 50 ml/min

- Negative pregnancy test for women of child¬bearing potential (urine or serum)

- Age over 18 years

- Ability to provide written informed consent

Exclusion Criteria:

- Known metastases to the brain

- Chemotherapy, external beam radiation or immunotherapy within 4 weeks prior to study.
Limited field external beam radiotherapy to prevent pathological fractures is
allowed, when unirradiated, evaluable lesions elsewhere are present.

- Prior angiogenesis inhibitors within 4 weeks; bevacizumab within 8 weeks

- Cardiac disease with New York Heart Association classification of III or IV

- Patients who are pregnant, nursing or of reproductive potential and are not
practicing an effective method of contraception

- Any unrelated illness, e.g. active infection, inflammation, medical condition or
laboratory abnormalities, which in the judgement of the investigator will
significantly affect patients' clinical status

- Life expectancy shorter than 6 months.