Immunotherapeutic Strategies for Brain Tumors

Cancer immunotherapy is the use of the immune system to reject cancers. The main premise is to harness the patient's immune system to attack the malignant tumor cells. This area of research has made tremendous progresses, and the United States Food and Drug Administration recently approved a vaccine for prostate cancers as the first approval for vaccines against non-viral cancers (Kantoff et al., 2010). However, when it comes to central nervous system (CNS) tumors, while early phase immunotherapy trials showed encouraging outcomes, the immunological microenvironment of the CNS and tumors arising in the CNS is still believed to be suboptimal for sufficient antitumor immune responses to mediate clinically-meaningful changes in situ (Okada, H. et al., 2009; Walker, P. R. et al., 2003). In this chapter, we first discuss recent advances in the CNS and CNS tumor immunology. We address factors that may promote immune escape of gliomas. We also review advances in passive and active immunotherapy strategies for glioma, with an emphasis on lessons learned from recent early phase clinical trials. We also discuss novel immunotherapy strategies that have been recently tested in non-CNS tumors with great potential for application to CNS tumors. We will finally discuss how each of these promising strategies can be combined to achieve clinical benefit for patients with CNS tumors.