T cell immunity in patients with malignant glioma: recent progress in dendritic cell-based immunotherapeutic approaches.

Despite dramatic advances in surgical technique, imaging, and adjuvant radiotherapy or chemotherapy, the prognosis for patients with malignant glial tumors remains dismal. Based on the current knowledge regarding immune responses in the healthy central nervous system (CNS) and glioma-bearing hosts, we discuss dendritic cell (DC)-based immunotherapeutic approaches for malignant gliomas and the relevance of recent clinical trials and their outcomes. It is now recognized that the CNS is not an immunologically tolerated site, and clearance of arising glioma cells is a routine physiological function of the normal, non-compromised immune system. To escape from immune surveillance, however, clinically apparent gliomas develop complex mechanisms that suppress tumoricidal immune responses. Although the use of DCs for the treatment of glioma patients may be the most appropriate approach, an effective treatment paradigm for these tumors may eventually require the use of several types of treatment. Additionally, given the heterogeneity of this disease process and an immune-refractory tumor cell population, the series use of rational multiple modalities that target different tumor characteristics may be the most effective therapeutic strategy to treat malignant gliomas.