[Immunotherapy of tumors of the central nervous system]

Malignant brain tumors are rapidly fatal and adjunction of chemo- and radio-therapy to surgical treatment has little changed their poor prognosis. The development of basic and clinical research in immunology of brain tumors has lead to new therapeutic strategies: 1) Humoral factors: Monoclonal antibodies (MAbs): alone or conjugated (to toxins, radionucleides or chemotherapeutic agents), MAbs can theoretically recognize antigens expressed by tumor cells and reach this target with high specificity. Large amounts of tumoricidal agents could be given to the tumor with low toxic effects to normal tissues. 2) Cellular factors: LAK cells: (lymphokine-activated-killer-cells) and activated TILs (tumor-infiltrating-lymphocytes) are autologous cytotoxic cells which can be produced by ex-vivo culture techniques and infused to the patient. These are very potent tumor-killer cells in vitro, however their in vivo effect is far less dramatic at the moment. 3) Cytokines: interferons, interleukins and other biological modifiers can act either directly on the tumor cells (cytotoxic effect) or indirectly through the modulation of the host-to-tumor response. 4) Combination of humoral and cellular factors: bispecific monoclonal antibodies are hybrid-molecules built from two different MAbs which can recognize two different targets, usually a tumor antigen on one hand and the T-cell-receptor (T 3) on the other hand. This combination of humoral and cellular effectors can theoretically lead to a preferential binding of effector cells to the tumor. All these new techniques are extensively studied in research laboratories and clinical trials without clear therapeutical benefit for the moment.