Clinical Trial of All-trans-retinoic Acid, Bevacizumab and Atezolizumab in Colorectal Cancer

The main purpose of this clinical trial is to learn about the good and the bad effects of all trans retinoic acid (ATRA), atezolizumab and bevacizumab as a possible treatment for advanced colorectal patients. Participants will be treated with the following combination of these drugs: 1. ATRA will be given in a pill form to be taken twice a day at home for 7 days starting on day 1 of a cycle. 2. Atezolizumab will be given through a vein in arm or through mediport over 60-90 minutes every 2 weeks in the outpatient chemotherapy infusion centers at UTSW. 3. Bevacizumab will be given through a vein in arm or through mediport over 20-40 minutes every 2 weeks in the outpatient chemotherapy infusion centers at UTSW.