Capecitabine and Bevacizumab With or Without Atezolizumab in Treating Patients With Refractory Metastatic Colorectal Cancer

This randomized phase II trial studies how well capecitabine and bevacizumab with or without atezolizumab work in treating patients with colorectal cancer that is not responding to treatment and has spread to other places. Immunotherapy with monoclonal antibodies, such as atezolizumab and bevacizumab, may help the body?s immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Drugs used in chemotherapy, such as capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving atezolizumab with capecitabine and bevacizumab may be a better way in treating colorectal cancer.