Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically confirmed carcinoma of the colon or rectum with
radiologically confirmed metastases or clinically confirmed incurability No hepatic or CNS
metastases Progression following fluorouracil (5-FU) alone or with a modulator (e.g.,
leucovorin, PALA, levamisole, interferon) Measurable disease outside prior radiotherapy
fields The following are not considered measurable: Pleural effusion or ascites
Osteoblastic lesions or evidence of disease on bone scan alone Progressive irradiated
lesions alone Bone marrow involvement Brain metastases Malignant hepatomegaly by physical
exam alone Chemical markers (e.g., CEA)

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Zubrod 0-2 Life expectancy:
At least 16 weeks Hematopoietic: Absolute neutrophil count at least 1,800/mm3 Platelet
count at least 125,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL Renal: Creatinine
no greater than 1.5 mg/dL Other: No concurrent infection Afebrile for at least 3 days
prior to treatment unless fever due to tumor No known HIV infection No other medical
condition that precludes protocol participation No second malignancy within 5 years
except: Nonmelanomatous skin cancer Curatively treated in situ cervical carcinoma No
pregnant or nursing women Negative pregnancy test required of fertile women Effective
contraception required of fertile women Blood/body fluid analyses within 7 days prior to
registration Imaging/exams for tumor measurement within 21 days prior to registration

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior mouse-based vaccines or monoclonal
antibodies Chemotherapy: At least 2 weeks since prior 5-FU or at least 1 week past the AGC
nadir, whichever is later No other prior chemotherapy except irinotecan Endocrine therapy:
Not specified Radiotherapy: At least 6 months since radiotherapy Surgery: Not specified