S9923 R115777 in Treating Patients With Advanced Colorectal Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed advanced colorectal adenocarcinoma Well differentiated OR Moderately well differentiated OR Poorly differentiated Distant metastases not surgically curable Measurable disease No prior treatment for disseminated disease No known brain metastases PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Zubrod 0-1 Life expectancy: Not specified Hematopoietic: Absolute granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) SGOT or SGPT no greater than 2.5 times ULN Renal: Creatinine no greater than 2.0 mg/dL Other: Not pregnant or nursing Fertile patients must use effective contraception Must be able to swallow or receive enteral medications through gastrostomy feeding tube No intractable nausea or vomiting No other prior malignancy for the past 5 years except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or any adequately treated stage I or II cancer in complete remission PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior adjuvant immunotherapy and recovered No concurrent immunotherapy Chemotherapy: At least 4 weeks since prior adjuvant chemotherapy and recovered No other concurrent chemotherapy Endocrine therapy: No concurrent hormonal therapy Radiotherapy: At least 4 weeks since prior radiotherapy and recovered No more than 25% of total area of bone marrow irradiated No concurrent radiotherapy Surgery: At least 2 weeks since prior surgery and recovered Other: No concurrent proton pump inhibitors No other concurrent anticancer therapy