Capecitabine + Bevacizumab in Patients With Recurrent Glioblastoma

Primary Objective: To achieve a 20-fold MDSC reduction in the concentration of circulating MDSCs after treatment with low dose capecitabine. Secondary Objectives: 1. To determine the concentration of circulating MDSCs in patients with recurrent glioblastoma after treatment with low dose capecitabine 2. To determine the concentration of tissue MDSCs and T-regulatory cells in resected glioblastoma after treatment with low dose capecitabine 3. To determine the safety and toxicity of continuous low dose capecitabine with and without standard dose bevacizumab. Exploratory Objective: To obtain a signal for efficacy as measured by progression-free survival rate at 6 months