Regorafenib and Nivolumab in Mismatch Repair (MMR) Refractory Colorectal Cancer

The main purpose of this study is to test the safety, tolerable side effects, and determine the highest tolerable dose of the combination of Regorafenib and Nivolumab. Researchers want to find out if this combination of Regorafenib and Nivolumab can help people with metastatic colorectal cancer with mismatch repair (MMR) proficiency.