Bryostatin 1 in Treating Patients With Metastatic Colorectal Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed colorectal cancer Unresectable disease Measurable disease No uncontrolled brain metastases PATIENT CHARACTERISTICS: Age: Any age Performance status: SWOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: Absolute neutrophil 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) AST no greater than 2.5 times ULN Renal: Creatinine no greater than 1.5 times ULN Other: No active infection Not pregnant or nursing Negative pregnancy test for premenopausal women Fertile patients must use effective contraception No concurrent uncontrolled systemic disorders No prior malignant disease within the past year except in situ carcinoma of the cervix or curatively treated basal cell carcinoma of the skin No history of allergy to bryostatin 1 or its vehicle PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent immunotherapy Chemotherapy: Only one prior chemotherapy regimen in the adjuvant or metastatic setting allowed At least 3 weeks since prior chemotherapy (6 weeks for nitrosoureas) No other concurrent chemotherapy Endocrine therapy: No concurrent hormonal therapy (except contraceptives, appetite stimulants and replacement steroids) Radiotherapy: At least 3 weeks since prior radiotherapy No concurrent radiation therapy No concurrent palliative radiation therapy to only site of measurable disease Surgery: Not specified Other: At least 1 month since prior use of any other investigational agent No concurrent use of experimental medications