This phase II trial is studying how well giving azacitidine together with entinostat works in treating patients with metastatic colorectal cancer. Drugs used in chemotherapy, such as azacitidine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Entinostat may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Giving azacitidine together with entinostat may kill more tumor cells.