1. Advanced unresectable, metastatic or recurrent colorectal carcinoma (CRC) for which treatment with FOLFOX6 with or without bevacizumab, FOLFIRI with or without bevacizumab, CAPOX, or regorafenib would be acceptable as determined by the Investigator. FOLFIRI-refractory patients with CRC enrolling on the FOLFIRI study arm must have failed treatment with one FOLFIRI with or without bevacizumab regimen for unresectable or metastatic disease. Treatment failure is defined as progression of disease (clinical or radiologic) during treatment with FOLFIRI with or without bevacizumab or < 3 months after the last dose of treatment with FOLFIRI with or without bevacizumab. Patients with CRC enrolling on the regorafenib arm of this study will have previously received at least two previous lines of therapy for advanced colorectal cancer, and will have previously received treatment with a fluoropyrimidine, oxaliplatin, and irinotecan. Patients with K-ras wild type tumors enrolling on the regorafenib arm will also have previously received either cetuximab or panitumumab.