Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed metastatic adenocarcinoma of the colon or rectum

- Bidimensionally measurable disease

- At least 2.0 x 2.0 cm

- Failed prior fluoropyrimidine and irinotecan chemotherapy in adjuvant or metastatic
setting

- Must have had disease progression while receiving chemotherapy OR

- If received fluorouracil with or without irinotecan in adjuvant setting, must
also have failed therapy with these agents in metastatic setting (unless
manifesting metastatic disease during adjuvant therapy)

- No known CNS metastases

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Performance status:

- Karnofsky 70-100%

Life expectancy:

- Not specified

Hematopoietic:

- Hemoglobin at least 9 g/dL

- Absolute neutrophil count at least 1,500/mm^3

- WBC at least 3,000/mm^3

- Platelet count at least 100,000/mm^3

Hepatic:

- Bilirubin no greater than 1.5 times upper limit of normal (ULN)

- AST/ALT no greater than 2.5 times ULN (5 times ULN if liver metastases present)

- Alkaline phosphatase no greater than 2.5 ULN (5 times ULN if bone or liver metastases
present)

Renal:

- Creatinine no greater than 1.5 times ULN

Cardiovascular:

- No New York Heart Association class III or IV congestive heart failure

- No myocardial infarction within the past 6 months

Gastrointestinal:

- No bowel obstruction

- No active uncontrolled malabsorption syndrome

Other:

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No active infection

- No other prior malignancy within the past 5 years except carcinoma in situ of the
cervix or non-melanoma skin cancer

- No other active cancers, including stable disease on adjuvant therapy

- No other medical condition that would preclude study

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- See Chemotherapy

- At least 2 weeks since prior biologic therapy and recovered

Chemotherapy:

- See Disease Characteristics

- No more than 2 prior cytotoxic chemotherapy regimens for metastatic disease

- Monoclonal antibody (MOAB) therapy and antiangiogenic agents not included as prior
cytotoxic chemotherapy

- At least 3 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) and
recovered

Endocrine therapy:

- Not specified

Radiotherapy:

- At least 3 weeks since prior radiotherapy and recovered

Surgery:

- No prior total gastrectomy

Other:

- No other concurrent investigational agents