Semyon A. Sinyavskiy

Glioblastoma is currently an incurable disease despite the development of a wide variety of therapeutic approaches, from surgical methods to immunotherapy. In current clinical practice, treatment typically involves a combination of existing methods, often comprising three stages: tumor resection, radiotherapy, and chemotherapy. Modern research offers improved chemotherapy strategies, as well as combinations of chemotherapy with immunotherapy. However, the efficacy of these therapies is profoundly influenced by factors such as tumor and peritumoral heterogeneity, alongside complex molecular signaling pathways. Optimizing glioma treatment requires a rigorous mechanistic understanding of individual approaches and their synergistic effects. This review comprehensively details current glioblastoma therapeutic strategies and critically evaluates key reference models for assessing combination therapy efficacy and their inherent limitations. A deeper understanding of these mechanisms and models will refine the investigation of observed therapeutic effects and accelerate the translation of promising in vitro approaches to effective clinical management of malignant gliomas.

Reactive oxygen species (ROS) play a key role in cancer progression and antitumor therapy. Glioblastoma is a highly heterogeneous tumor with different cell populations exhibiting various redox statuses. Elevated ROS levels in cancer cells promote tumor growth and simultaneously make them more sensitive to anticancer drugs, but further elevation leads to cell death and apoptosis. Meanwhile, various subsets of tumor cells, such a glioblastoma stem cells (GSC) or the cells in tumor microenvironment (TME), demonstrate adaptive mechanisms to excessive ROS production by developing effective antioxidant systems such as glutathione- and thioredoxin-dependent. GSCs demonstrate higher chemoresistance and lower ROS levels than other glioma cells, while TME cells create a pro-oxidative environment and have immunosuppressive effects. Both subpopulations have become an attractive target for developing therapies. Increased expression of thioredoxin reductase (TrxR) is often associated with tumor progression and poor patient survival. Various TrxR inhibitors have been investigated as potential anticancer therapies, including nitrosoureas, flavonoids and metallic complexes. Gold derivatives are irreversible inhibitors of TrxR. Among them, auranofin (AF), a selective TrxR inhibitor, has proven its effectiveness as a drug for the treatment of rheumatoid arthritis and its efficacy as an anticancer agent has been demonstrated in preclinical studies in vitro and in vivo. However, further clinical application of AF could be challenging due to the low solubility and insufficient delivery to glioblastoma. Different delivery strategies for hydrophobic drugs could be used to increase the concentration of AF in the brain. Combining different therapeutic approaches that affect the redox status of various glioma cell populations could become a new strategy for treating brain tumor diseases.