OBJECTIVES: I. Compare the efficacy of fluorouracil with or without IM-862 in terms of progression free survival in patients with previously untreated or recurrent metastatic adenocarcinoma of the colon or rectum. II. Determine the toxicity of IM-862 and fluorouracil in these patients. III. Determine the efficacy of IM-862 in combination with irinotecan in terms of progression free survival in patients who have disease progression after receiving fluorouracil. IV. Obtain preliminary data on molecular markers of response and time to progression by determining levels of genes involved in adhesion, angiogenesis, apoptosis, and drug resistance prior to and during chemotherapy. V. Determine the molecular correlates for response and time to progression through analysis of serum and urine markers of angiogenesis, such as vascular endothelial growth factor and fibroblast growth factor, in patients treated with IM-862 in combination with fluorouracil or irinotecan. VI. Compare the quality of life of patients treated with these regimens.