Glioblastoma at the crossroads: current understanding and future therapeutic horizons

Abstract

Glioblastoma (GBM) remains the most aggressive and lethal brain tumor in adults and poses significant challenges to patient survival. This review provides a comprehensive exploration of the molecular and genetic landscape of GBM, focusing on key oncogenic drivers, such as epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), and the PI3K/AKT/mTOR pathway, which are critical for tumorigenesis and progression. We delve into the role of epigenetic alterations, including DNA methylation and histone modifications, in driving therapy resistance and tumor evolution. The tumor microenvironment is known for its pivotal role in immune evasion, with tumor-associated macrophages, myeloid-derived suppressor cells, and regulatory T cells creating an immunosuppressive niche that sustains GBM growth. Emerging therapies, such as immunotherapies, oncolytic viral therapies, extracellular vesicle-based approaches, and non-coding RNA interventions, are highlighted as promising avenues to disrupt GBM pathogenesis. Advances in precision medicine and innovative technologies, including electric field therapy and locoregional treatments, are discussed for their potential to overcome the blood‒brain barrier and treatment resistance. Additionally, this review underscores the importance of metabolic reprogramming, particularly hypoxia-driven adaptations and altered lipid metabolism, in fueling GBM progression and influencing the therapeutic response. The role of glioma stem cells in tumor recurrence and resistance is also emphasized, highlighting the need for targeted therapeutic approaches. By integrating molecular targeting, immune energetics, and technological advancements, this review outlines a multidisciplinary framework for improving GBM treatment outcomes. Ultimately, the convergence of genetic, metabolic, and immune-based strategies offers transformative potential in GBM management, paving the way for increased patient survival and quality of life.

Fig. 1

Glioblastoma landscape and path towards targeted therapies. 1. The pie chart illustrates glioma trends, with a focus on glioblastoma (GBM) prevalence in the United States. Data source: Cancer Stat Facts: Brain and other nervous system cancers identified by the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program, 2014–2020. 2. GBM, marked by its pronounced molecular, genetic, and cellular heterogeneity, presents substantial obstacles for accurate diagnosis and effective treatment. 3. Advanced diagnostic methods, leveraging biofluid biomarkers such as liquid biopsies and circulating biomolecules, alongside high-definition detection technologies, are crucial for precise detection. 4. These innovations are driving the development of targeted and more effective therapies for GBM treatment

Fig. 2

Clinical and molecular grading of gliomas. Schematic representation of the molecular classification and histopathological grading of gliomas, along with their cellular origins and progression. The bottom panel shows a developmental lineage from neural stem cells to neurons, astrocytes, and glial progenitors. Pilocytic astrocytomas (Grade I) are typically circumscribed and low grade, whereas diffuse astrocytomas (Grade II), anaplastic astrocytomas (Grade III), and glioblastomas (Grade IV) represent progressive stages of malignancy and infiltrative behavior. The top panel highlights the molecular subtypes of glioblastoma: proneural, neural, classical, and mesenchymal, each defined by distinct genetic alterations such as IDH1/2, EGFR, p53, PTEN, NF1, and others. These subtypes correlate with the primary (de novo) or secondary (progression from lower-grade gliomas) origins of glioblastoma. This classification underscores the integration of molecular and clinical parameters for diagnosis, prognosis, and therapeutic decision-making in gliomas

Fig. 3

Epigenetic characteristics of glioblastoma and their role in pathogenesis. The figure depicts the key epigenetic mechanisms contributing to glioblastoma (GBM) development, including histone modifications, DNA methylation, ATRX mutations, and TERT promoter mutations. Histone modifications such as methylation (Me3) and acetylation (Ac) at specific lysine residues regulate chromatin accessibility and gene expression. DNA methylation, which is catalyzed by DNA methyltransferases (DNMTs), further influences gene silencing or activation. ATRX mutations impair chromatin remodeling by disrupting the ATRX-DAXX complex, which is responsible for H3.3 deposition, leading to altered transcription and increased chromatin accessibility. TERT promoter mutations result in aberrant telomerase expression, contributing to tumor cell immortality

Fig. 4

Genetic alterations driving glioblastoma pathogenesis. The schematic illustrates key oncogenic genetic alterations contributing to glioblastoma (GBM) development and progression. Receptor tyrosine kinases (RTKs), such as EGFR, PDGFR, FGFR, and VGFR, initiate downstream signaling cascades, including the PI3K/AKT/mTOR and RAS/RAF/MEK/ERK pathways. Loss of tumor suppressors (e.g., PTEN, CDKN2A, RB1, p53) and overactivation of oncogenes (e.g., EGFR, MDM2, CDK4/6, TERT, MYB, SOX2, AREG) promote cell cycle progression, proliferation, stemness, survival, angiogenesis, and resistance to apoptosis. DNA damage response elements (ATM/ATR-Chk1/Chk2) are activated by radiation and chemotherapy (TMZ) but are frequently bypassed in GBM. Downstream transcriptional regulators such as MYB and SOX2 further enhance tumor cell plasticity and malignancy. Collectively, these alterations reprogram the tumor cell phenotype, driving GBM progression and therapy resistance

Fig. 5

Deregulated molecular signaling pathways and crosstalk in glioblastoma. This illustration highlights key oncogenic signaling pathways and their interconnected roles in glioblastoma (GBM) pathogenesis. Dysregulated pathways such as the PI3K/AKT/mTOR, MAPK/ERK, p53, NF-κB, JAK/STAT, β-catenin, and Notch pathways collectively drive tumor progression, survival, and resistance to therapy. NF-κB activation, triggered by TNFα/TNFR1 and the IKK complex, integrates inflammatory signaling, whereas cytokine-mediated activation of the JAK/STAT pathway promotes the transcription of survival genes. The Wnt/β-catenin and Notch pathways further support stemness, angiogenesis, and immune modulation. The convergence and crosstalk among these pathways contribute to the complexity and aggressiveness of GBM

Fig. 6

Key immune signaling pathways regulating tumor-associated immunosuppression. In macrophages, CSF-1 or IL-34 binds to the CSF-1 receptor, inducing rapid dimerization and autophosphorylation of tyrosine residues. This activation triggers downstream signaling through the PI3K/AKT and JAK/STAT pathways, regulating macrophage polarization. CTLA-4, which is expressed on activated T cells, binds to CD80/CD86 on APCs. Upon engagement, CTLA-4 signaling dephosphorylates TCR signaling components, inhibiting CD3 and ZAP70 activation and suppressing the RAS signaling pathway. CTLA-4 signaling disrupts AKT phosphorylation, negatively regulating the cell cycle and suppressing key transcription factors such as NF-κB, AP-1, and NF-AT. PD-1 interacts with its ligands, leading to the phosphorylation of two tyrosine residues on its cytoplasmic tail. This phosphorylation recruits SHP-1 and SHP-2 to the ITSM motif, inhibiting the PI3K/AKT/mTOR pathway, reducing metabolic activity, and promoting T cell exhaustion. In the case of TGF-βR2 ligand binding, the receptor activates and facilitates PI3K and AKT signaling through physical interaction with the PI3K subunit. This cascade leads to mTOR kinase activation, which drives translational responses. Collectively, these signaling pathways induce IDO1 activation, which converts tryptophan to kynurenine, thereby enhancing tumor immune evasion through immune suppression. The CD39/CD73 pathway hydrolyzes extracellular ATP into adenosine, an immunosuppressive metabolite. Adenosine prevents tyrosine phosphorylation of ZAP70, AKT, and ERK1/2 in naive αCD3/CD28-stimulated CD8⁺ T cells, impairing their activation

Fig. 7

Current and emerging glioblastoma therapeutics for clinical management. The figure provides an overview of current therapeutic strategies used in the clinical management of glioblastoma (GBM). Locoregional treatments include surgical resection, laser interstitial thermal therapy (LITT), and radiation, which aim to eliminate tumor tissue through direct cytotoxic effects. Tumor-treating fields (TTFs) and directional nonrotating electric field therapy (dnEFTs) promote mitotic disruption and apoptosis. Chemical interventions include chemotherapy (TMZ), which induces G2/M arrest and apoptosis, and immunotherapy, which enhances T cell-mediated tumor killing. Oncolytic viruses induce immunogenic cell death, whereas therapeutic vaccines such as peptides, mRNAs, viral vectors, and dendritic cell-based platforms stimulate immune surveillance. Combination therapies leverage multiple modalities to simultaneously target diverse oncogenic pathways, offering a promising route toward overcoming resistance and advancing personalized GBM treatment

Fig. 8

Major challenges and future therapeutic prospects in glioblastoma treatment. Key aspects, such as glioma stem cells (GSCs), therapy resistance, the blood‒brain barrier (BBB), metabolic reprogramming, and immune adaptation, are highlighted. 1. The glioblastoma (GBM) tumor microenvironment (TME) contributes to therapy resistance and disease progression. GSCs exhibit self-renewal capacity and plasticity, driving tumor recurrence and treatment failure. The proneural-to-mesenchymal transition underscores the heterogeneity of GBM, further complicating treatment strategies. 2. Therapy resistance mechanisms, including genetic mutations, epigenetic modifications, and adaptive survival pathways, are key obstacles to effective treatment. These mechanisms enable GBM cells to evade chemotherapy, radiotherapy, and targeted therapies. 3. This study highlights the challenges of overcoming the BBB, which restricts drug penetration and limits the efficacy of systemic therapies. Prospects involve strategies such as engineered EV-mediated drug delivery, efflux pump inhibitors, and modified pericytes and astrocytes to increase therapeutic access to the tumor site. 4. Metabolic reprogramming involves altered ATP production, lipid metabolism, and glycolysis, which provide energy for rapid tumor growth. Targeting metabolic vulnerabilities through the use of mitochondrial inhibitors, glycolysis modulators, and lipid metabolism disruptors is an emerging therapeutic approach. 5. In GBM, tumor-associated macrophages (TAMs), regulatory T cells (Tregs), and exhausted CD8⁺ T cells (Tex) contribute to an immunosuppressive environment. Immunotherapy strategies, including checkpoint inhibitors, dendritic cell (DC)-based vaccines, and the reprogramming of macrophage phenotypes (M2 to M1), aim to restore antitumor immunity and improve therapeutic responses. This schematic underscores the multifaceted nature of GBM pathophysiology and emphasizes the need for multimodal approaches integrating targeted therapy, immunotherapy, metabolic intervention, and BBB-modulating strategies to increase treatment efficacy and improve patient outcomes

Fig. 9

Transcriptional and epigenetic regulation and functional dynamics in CD8⁺ T cell exhaustion. The illustration depicts the intricate interplay between signaling pathways and transcriptional regulators that drive CD8⁺ T cell exhaustion in the TME. Key pathways include the PI3K/AKT signaling pathway and the modulation of the activity of FOXO1/3 transcription factors. In the nucleus, TCF-1 promotes stemness by upregulating genes such as ID-3, EOMES, Bcl-2/6, and c-Myb. Together with TCF-1, FOXO1/3 represses effector T cell (Teff) functions by regulating exhaustion-associated genes (ID-2, Tbet, Blimp-1, RUNX3, and TCF-7). Exhausted T cells progress through a continuum, transitioning from progenitor-like (pro/stem-like Tex) states (PD-1^low, TCF-1⁺, and CXCR3⁺) to terminally exhausted (terminal Tex) states (PD-1^hi, TOX^hi, and TCF-1⁻). FOXO1/3 also govern antioxidant and proapoptotic genes and regulate cell cycle arrest genes, maintaining cellular integrity and upregulating PD-1 and TOX. PD-1 and TOX function as central mediators of epigenetic regulation, influencing chromatin accessibility and transcriptional programming to stabilize exhaustion phenotypes. This PD-1 epigenetic regulation shapes T cell function and metabolic fitness within the tumor microenvironment

Fig. 10

Increased therapeutic potential of CAR-T cells. The figure illustrates key strategies to optimize CAR-T cell therapy for GBM treatment. a. Multiantigen targeting improves CAR-T cell precision and efficacy against heterogeneous tumors. b. Advanced receptor designs, including costimulatory domain modifications and switch-controlled circuits such as synNotch CAR-T cells, enhance activation, persistence, and adaptability while sparing normal cells. c. Genome engineering introduces transcriptional and epigenetic changes to reduce exhaustion, improve memory, and increase cytokine production for sustained therapeutic effects. d. Inhibiting ubiquitin ligase-mediated degradation enhances CAR-T cell therapeutic potential