Present and Future of Immunotherapy in Patients With Glioblastoma: Limitations and Opportunities

Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor. Standard therapies, including surgical resection, chemoradiation, and tumor treating fields, have not resulted in major improvements in the survival outcomes of patients with GBM. The lack of effective strategies has led to an increasing interest in immunotherapic approaches, considering the success in other solid tumors. However, GBM is a highly immunosuppressive tumor, as documented by the presence of several mechanisms of immune escape, which may represent a reason why immunotherapy clinical trials failed in this kind of tumor. In this review, we examine the current landscape of immunotherapy strategies in GBM, focusing on the challenge of immunoresistance and potential mechanisms to overcome it. We discussed completed and ongoing clinical trials involving immune checkpoint inhibitors, oncolytic viruses, vaccines, and CAR T-cell therapies, to provide insights into the efficacy and outcomes of different immunotherapeutic interventions. We also explore the impact of radiotherapy on the immune system within the GBM microenvironment highlighting the complex interactions between radiation treatment and the immune response.