New perspectives in glioma immunotherapy

Glioblastoma (GBM) is a deadly tumor, which in spite of surgery and radio/chemotherapy frequently undergoes relapses related to the infiltration of the normal parenchyma and to resistance to cytotoxic and radiation therapy. Immunotherapy may represent a promising approach, which may complement existing therapies with the aim of eliminating residual tumor cells, through their selective targeting by immune effector cells or antibodies. This goal can be achieved through different approaches, based either on the induction of an immune response of the host, or by the injection of in vitro generated effector cells or monoclonal antibodies. Recent advances in the immunobiology of GBM and of its stem cell compartment will help in the development of more effective immunotherapy protocols. To this aim, the identification of antigens and receptors involved in GBM/immune cell interactions and of GBM immune escape mechanisms will provide new targets and tools. In this review we will discuss active immunotherapy approaches, including molecular-defined, GBM cell-based and dendritic-cell based vaccines. In addition, cytokines such as interferons and several interleukins can be used to enhance the immune response, both as recombinant molecules and by gene transfer technologies. Monoclonal antibodies or other ligands specific for GBM- or neovasculature-associated targets are now available in different genetically modified formats and can be used as such or for the targeted delivery of active compounds. Finally the in vitro activation and expansion of specific or innate immunity effector cells endowed with anti-GBM properties may provide an additional weapon for adoptive imunotherapy approaches.