CB-839 + Capecitabine in Solid Tumors and Fluoropyrimidine Resistant PIK3CA Mutant Colorectal Cancer

This study has two portions. The main goal of the Phase I portion of this research study is to see what doses of CB-839 and capecitabine can safely be given to patients without having too many side effects. Other purposes of this research study will be to determine what side effects are seen with this combination of medicines. The Phase II portion of the study will test how many patients show shrinkage in their tumor with this combination of medicines and what changes occur inside the cancer cells and blood cells after treatment.