Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically or cytologically confirmed adenocarcinoma of the colon or rectum that
is incurable with conventional therapy

- Metastatic or recurrent disease

- At least 1 unidimensionally measurable lesion

- At least 20 mm by conventional techniques or at least 10 mm by spiral CT scan

- Disease must be accessible to biopsy

- No known brain metastases

PATIENT CHARACTERISTICS:

Age

- 18 and over

Performance status

- ECOG 0-1 OR

- Karnofsky 70-100%

Life expectancy

- More than 3 months

Hematopoietic

- Absolute granulocyte 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 1.25 times upper limit of normal (ULN)

- AST or ALT no greater than 3 times ULN (less than 5 times ULN if liver metastases
present)

Renal

- Creatinine no greater than 1.25 times UNL OR

- Creatinine clearance at least 50 mL/min

Cardiovascular

- No symptomatic congestive heart failure

- No unstable angina pectoris

- No cardiac arrhythmia

Other

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No psychiatric illness or social situation that would preclude study compliance

- No other uncontrolled concurrent illness

- No ongoing or active infection

- No other active malignancy within the past 3 years except curatively treated
nonmelanoma skin cancer or carcinoma in situ of the cervix

- No grade 1 or greater peripheral neuropathy due to prior chemotherapy

- No significant traumatic injury within the past 21 days

PRIOR CONCURRENT THERAPY:

Biologic therapy

- Not specified

Chemotherapy

- No more than 1 line of prior chemotherapy (including any combination of fluorouracil,
irinotecan, and/or oxaliplatin) for metastatic disease

- At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) and
recovered

- Prior adjuvant chemotherapy allowed

- No concurrent cytotoxic chemotherapy

Radiotherapy

- More than 4 weeks since prior radiotherapy and recovered

- No prior radiotherapy to measurable target lesion unless disease progression has
occurred after radiotherapy

- No concurrent radiotherapy to the sole site of measurable disease

Surgery

- More than 21 days since prior major surgery

Other

- No other concurrent investigational agents

- No concurrent combination antiretroviral therapy for HIV-positive patients