This is an open label, multi-center, Phase 1/2 dose escalation study of BBI608 administered in combination with either FOLFOX6 with and without bevacizumab, or CAPOX, or FOLFIRI with and without bevacizumab, or regorafenib, or irinotecan. A study cycle will consist of daily and continuous oral administration of BBI608 for four weeks (28 days) in combination with FOLFOX6 with and without bevacizumab, or CAPOX, or FOLFIRI with and without bevacizumab, or regorafenib, or irinotecan.