Plerixafor (AMD3100) and Bevacizumab for Recurrent High-Grade Glioma

Plerixafor in combination with bevacizumab is a drug combination that may stop cancer cells from growing abnormally. Bevacizumab, also known as Avastin, is FDA approved for use in patients with recurrent glioblastoma and has been studied extensively in other types of solid tumors. Plerixafor, also known as Mozobil, is FDA approved for use in patients with non-Hodgkin's lymphoma and multiple myeloma and has been used in treatment for other cancers. Information from experiments in laboratories suggests that the combination of plerixafor and bevacizumab may help prevent the growth of gliomas. Part 1: The investigators are looking for the highest dose of plerixafor that can be given safely with bevacizumab (with a 21 days on/7 days off regimen of plerixafor). The investigators will also do blood tests to find out how the body uses and breaks down the drug combination. Part 2: The investigators are looking to see if plerixafor can get past the blood-brain barrier and into brain tumors. The investigators will also do blood tests to find out how the body uses and breaks down the drug combination. Part 3: The investigators are looking for for more information re: safety and tolerability of plerixafor in combination with bevacizumab (with a 28 days on/0 days off regimen of plerixafor). The investigators will also do blood tests to find out how the body uses and breaks down the drug combination.