[Difficulties and prospects in the immunotherapy of gliomas]

Despite the spectacular development of clinical immunotherapy (IT) in the last decade, the regular treatment approaches for the most common central nervous system (CNS) tumors, the malignant gliomas (MGs) has not changed yet. The most important pitfalls of the routine application of immunotherapy can be imputed to the special and originally immunosuppressed microenvironment and the extreme heterogeneity of MGs, however the defensive role of the blood-brain barrier, the general usage of steroids and the difficulties in the evaluation of brain images can also play a role in these types of difficulties. Additionally, in the case of MGs, well-accepted IT biomarker assays (PDL1 positivity, mismatch repair deficiencies, tumor mutation burden, etc.) generally reveal only minimal levels of immunogen activities. Nevertheless, there are some promising results with the utilization of checkpoint inhibitors and other IT modalities (such as virus-based therapies, tumor vaccines, adoptive T cell therapies) and with the combination of conventional oncotherapy methods in case of CNS malignancies, as well. In conclusion, although the CNS is not any more considered as an "immunological sanctuary" and despite some encouraging experimental and clinical results in CNS oncotherapy, the routine application of IT in case of MGs is still awaited.