Ursodiol, Combination Chemotherapy, and Bevacizumab in Treating Patients With Stage IV Colorectal Cancer

RATIONALE: Drugs used in chemotherapy, such as ursodiol, oxaliplatin, leucovorin, and fluorouracil, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Monoclonal antibodies, such as bevacizumab, can block tumor growth in different ways. Some block the ability of tumor cells to grow and spread. Others find tumor cells and help kill them or carry tumor-killing substances to them. Bevacizumab may also stop the growth of colorectal cancer by blocking blood flow to the tumor. Giving ursodiol together with leucovorin calcium, fluorouracil, oxaliplatin, and bevacizumab may be an effective treatment for colorectal cancer. PURPOSE: This phase I trial is studying the side effects and best dose of ursodiol when given together with combination chemotherapy and bevacizumab in treating patients with stage IV colorectal cancer.