 One of the challenges of the practical application of immunotherapy for brain tumors is the lack of expression of tumor antigens as well as the down-regulation of MHC Class I and II molecules, which are needed for antigen presentation. Considering the ability of DAC to facilitate the expression of CT antigens and MHC molecules and the fact that it has good blood brain barrier penetration, it is reasonable to test this approach in a vaccine study for patients who have experienced disease recurrence. The use of a combined approach to tumor immunotherapy - antigen upregulation followed by vaccination - has not been studied in this patient population, and there is a strong biologic rationale for this strategy. 