Capecitabine + Bevacizumab in Patients With Recurrent Glioblastoma

This study involves participants with recurrent glioblastoma brain tumors (GBM). This means that a participant's brain tumor has either returned after being treated by a previous therapy, or has continued to progress despite being treated. The purpose of this study is to provide proof of concept that suppression of MDSCs (myeloid-derived suppressor cells) is feasible in patients with GBM. Rather than targeting tumor cells or immune checkpoints, which has been the focus of recent therapeutic efforts, direct targeting of MDSCs with low dose capecitabine has the potential to reverse the immunosuppressed microenvironment of GBM and thereby reduce tumors