The review, titled “Glioma Microenvironment: Cellular Crosstalk, Immunosuppression, and Novel Therapeutic Perspectives,” describes the tumor microenvironment as an active biological network rather than a passive structure surrounding cancer cells. Glioma cells release cytokines, chemokines, growth factors and extracellular-matrix-modifying enzymes that reshape neighboring cells. In response, immune and stromal cells alter their behavior in ways that can benefit the tumor. The result is a paradoxical state sometimes described as “inflammation without immunity”: immune cells accumulate in the tumor, but many become functionally suppressed and incapable of mounting an effective antitumor response.

Resident microglia, the brain’s innate immune sentinels, are among the first cells to be reprogrammed. Glioma-derived molecules such as Versican can push microglia toward a pro-tumorigenic phenotype. Once polarized, these cells may support invasion through matrix metalloproteinase-14, or MMP14, and other mediators including stress-inducible protein 1, secreted phosphoprotein 1 and epidermal growth factor. They can also contribute to immune suppression by expressing programmed death-ligand 1, or PD-L1, and transforming growth factor beta. These signals weaken local T-cell activity while helping malignant cells move through the surrounding brain tissue.

Circulating monocytes provide another major source of tumor-associated macrophages. Gliomas recruit these cells through chemokine systems such as the CCL2/CCR2 and CSF1/CSF1R pathways. After entering the tumor, monocytes differentiate into macrophages with a broad functional spectrum. A minority may retain inflammatory properties and release interleukin-1 beta, interleukin-27 and tumor necrosis factor. However, the review emphasizes that most adopt an anti-inflammatory and immunosuppressive state marked by PD-L1, transforming growth factor beta, interleukin-10 and arginase 1. These macrophages also promote blood-vessel formation through vascular endothelial growth factor and epidermal growth factor, while MMP2 helps remodel the extracellular matrix and opens pathways for invasion.

Other myeloid populations further reinforce this immune barrier. Neutrophils can be drawn into the glioma microenvironment through interleukin-8 signaling, where they may encourage additional recruitment of neutrophils and monocytes. Their expression of arginase 1 can deprive T cells of essential metabolic resources and restrict their ability to proliferate. Yet the review highlights an important exception: hybrid dendritic-like neutrophils may possess antitumor properties by presenting signals that prime T-cell cytotoxicity and support immune memory. Myeloid-derived suppressor cells, or MDSCs, are recruited through CCL2 and stromal cell-derived factor 1 alpha, also known as SDF-1α. They suppress adaptive immunity using arginase 1, inducible nitric oxide synthase, PD-L1 and transforming growth factor beta.

Dendritic cells, which normally function as professional antigen-presenting cells, are also undermined by the glioma environment. Tumor-derived vascular endothelial growth factor, interleukin-6 and interleukin-10 can interfere with dendritic-cell maturation and reduce their capacity to process and present tumor antigens. Without effective antigen presentation, T cells are not properly activated against malignant cells. Even when T cells do enter the tumor, they frequently encounter an environment dominated by inhibitory signals. Repeated engagement between PD-1 on T cells and PD-L1 on tumor or immune cells can drive exhaustion or apoptosis, while transforming growth factor beta and indoleamine 2,3-dioxygenase 1 further suppress T-cell metabolism and function. This helps explain why immune infiltration does not necessarily translate into tumor control.

The neural nature of the brain adds another layer of complexity. Research summarized in the review shows that glioma cells can form functional excitatory synapses with neurons. Through these connections, neuronal activity and neurotransmitters such as glutamate can directly stimulate tumor-cell signaling and growth. Glioma cells may also exploit gamma-aminobutyric acid and neurotrophic factors, including neuroligin-3, brain-derived neurotrophic factor, insulin-like growth factor 1 and semaphorin 4F. Neuroligin-3 is particularly important because neuronal activity can trigger its release, activating growth programs in glioma cells. This creates a feed-forward loop in which active neural circuits promote tumor expansion, while the expanding tumor becomes increasingly integrated into the surrounding brain network.

Astrocytes and oligodendrocyte-lineage cells are similarly drawn into the tumor-supporting system. Reactive astrocytes can communicate with glioma cells through gap junctions, allowing direct exchange of ions and signaling molecules. Additional interactions involving interleukin-11 and its receptor, as well as annexin A1-related signaling, may promote invasion and suppress T-cell immunity. Although the review gives less emphasis to oligodendrocyte-lineage cells, it identifies them as additional participants in glioma progression, with potential roles in angiogenesis and immune escape. Together, these findings challenge the traditional view that the malignant cell is the only biologically relevant target inside the brain.

The vascular system provides both nutrients and a route for tumor dissemination. Glioma-associated endothelial cells respond to vascular endothelial growth factor and fibroblast growth factor, driving the formation of abnormal blood vessels. These vessels are often tortuous, structurally fragile and poorly organized. Their dysfunction disrupts the blood-brain barrier, increasing the movement of peripheral immune cells into the tumor while simultaneously creating profound therapeutic obstacles. Abnormal perfusion can produce regions of hypoxia and impaired drug distribution, meaning that a medicine may reach some tumor compartments but fail to penetrate others. Lymphatic endothelial cells may also participate directly in tumor progression through the CCL21/CCR7 signaling axis, adding another route of communication between glioma cells and the surrounding tissue.

The review argues that these interconnected mechanisms demand a broader therapeutic strategy. Blocking tumor-cell proliferation alone may not be enough if microglia and macrophages remain immunosuppressive, neuronal activity continues to stimulate growth, and abnormal vessels prevent adequate drug delivery. Potential approaches include reprogramming tumor-associated macrophages, inhibiting monocyte recruitment through the CCL2/CCR2 or CSF1/CSF1R axes, targeting MDSCs, restoring dendritic-cell function and combining immune checkpoint blockade with methods that reverse T-cell exhaustion. Interfering with neuron-glioma synapses, neuroligin-3 signaling, glutamatergic stimulation or astrocyte-mediated communication could provide additional ways to disrupt the tumor’s neural support system. The authors present the glioma microenvironment not only as the central engine of therapeutic resistance but also as a source of new vulnerabilities. By dismantling the ecosystem that protects malignant cells, future treatments may move beyond attacking the tumor in isolation and instead disable the biological network that allows it to survive.

Subject of Research: Glioma tumor microenvironment and cellular crosstalk

Article Title: Glioma Microenvironment: Cellular Crosstalk, Immunosuppression, and Novel Therapeutic Perspectives

News Publication Date: 15 June 2026

Web References: https://doi.org/10.1097/CM9.0000000000004151

References: Zhao L. “Glioma Microenvironment: Cellular Crosstalk, Immunosuppression, and Novel Therapeutic Perspectives.” Chinese Medical Journal. DOI: 10.1097/CM9.0000000000004151

Image Credits: Chinese Medical Journal

Keywords: glioma, brain cancer, tumor microenvironment, neuro-oncology, microglia, macrophages, immunosuppression, T-cell exhaustion, glioma immunotherapy, neuron-tumor communication, astrocytes, tumor-associated macrophages, blood-brain barrier, cancer neuroscience

Gliomas, known for their aggressive recurrence and challenging brain involvement, continue to pose significant treatment barriers. Standard care usually involves a combination of radiotherapy and chemotherapy with temozolomide, but recurrence remains common, often accompanied by tumor residues in critical brain areas, limiting surgical options. Against this backdrop, anlotinib—a novel multi-targeted tyrosine kinase inhibitor known for its antiangiogenic and antitumor properties—has been posited as a potential adjunct to traditional chemotherapy.

The study enrolled patients who either experienced tumor relapse following the standard TMZ-radiotherapy regimen or had macroscopic residual tumors due to the involvement of eloquent brain regions, which restrict surgical removal. Between March 2018 and January 2021, these individuals embarked on a therapeutic protocol combining anlotinib, given as 12 mg once daily on a 14-days-on, 7-days-off schedule, with temozolomide administered at 200 mg/m² for 5 days followed by a 23-day break. Treatment was maintained until signs of disease progression or unacceptable toxicity emerged.

Efficacy was rigorously assessed via the Response Assessment in Neuro-Oncology (RANO) criteria, designed specifically for high-grade gliomas, enabling an accurate appraisal of tumor responses. Concurrently, the safety of this combined regimen was monitored using the National Cancer Institute’s Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 4.0, establishing a comprehensive safety profile.

Results observed after a median follow-up duration of over two years were illuminating. The median overall survival time, measured from recurrence until death or last follow-up, reached 17.87 months—a notable figure amidst typically poor prognoses associated with recurrent glioma. Survival rates at critical time points—1 year, 1.5 years, and 2 years—stood at 60.0%, 46.7%, and 36.7%, respectively, indicating sustained benefits from the treatment regimen.

Progression-free survival (PFS), reflecting the interval between treatment initiation and disease progression, had a median duration of 7.83 months, with the 6-month and 1-year PFS rates at 63.3% and 36.7%. These results suggest a meaningful delay in tumor advancement, offering patients critical time with improved quality of life.

Diving deeper into the patient subgroups, univariate analyses revealed pivotal insights. Patients diagnosed with WHO grade 2 gliomas showed significantly prolonged overall and progression-free survival compared to those with higher-grade tumors—grades 3 and 4. Specifically, median OS for grade 2 was an impressive 30.45 months, while grade 3 and grade 4 patients exhibited median survivals of 15.07 and 9.21 months respectively. Statistical analysis underscored the significance of tumor grade on survival outcomes, with a p-value of 0.035.

Age emerged as another critical prognostic factor influencing PFS. Patients aged 55 or younger experienced a markedly longer median progression-free survival of nearly 13 months, whereas those above 55 had a median PFS of 7.33 months. Although older patients trended toward shorter overall survival (10.53 months vs. 19.90 months), this did not reach statistical significance (p=0.106). Intriguingly, common genetic markers such as 1p/19q codeletion and IDH mutations—often considered prognostic in glioma—did not predict outcomes significantly in this cohort.

Multivariate analysis, which controls for confounding factors, corroborated that neither age, pathological grade, nor IDH mutation status independently predicted survival outcomes. These findings highlight the complexity of glioma biology and the need to consider multiple clinical parameters when forecasting treatment responses.

Safety evaluation revealed that the combination of anlotinib and temozolomide was generally well-tolerated. Toxicities were manageable and consistent with known side effect profiles of these agents, suggesting that the regimen could be integrated into clinical practice without imposing undue burden on patients. This tolerability is particularly important given the vulnerable patient population and the need for therapies balancing efficacy and quality of life.

This retrospective analysis, while limited by its sample size and single-center nature, positions anlotinib combined with temozolomide as a compelling therapeutic strategy for recurrent glioma. The survival benefits, coupled with acceptable toxicity, warrant further validation in larger, randomized controlled trials to delineate the precise role and mechanism of this combination.

The study’s findings infuse hope into the neuro-oncology community, where recurrent gliomas have long defied effective long-term control. If future trials confirm these outcomes, anlotinib plus TMZ could redefine the standard of care, offering patients extended survival and improved management of a daunting disease.

Continued research is expected to unravel the molecular underpinnings behind anlotinib’s enhanced efficacy when paired with temozolomide, potentially leading to biomarker-driven personalized treatment plans. Moreover, understanding resistance mechanisms and exploring combinations with other targeted therapies could further amplify clinical benefits.

In sum, this study exemplifies the dynamic progress in neuro-oncology therapeutics and underscores the critical need for innovative combinations in tackling recurrent gliomas. By harnessing the synergy of antiangiogenic agents like anlotinib with established chemotherapeutics, there is renewed optimism for improving patient outcomes in a landscape historically marked by therapeutic stagnation.

As this study gains attention, it catalyzes a broader conversation about integrating novel kinase inhibitors into glioma treatment regimens and prompts clinicians and researchers alike to reexamine current paradigms. The results advocate a future where precision oncology not only extends survival but also enhances the quality of life for glioma patients worldwide.

With gliomas continuing to challenge medical science, such advances reflect a triumph of innovation, perseverance, and the relentless pursuit of better therapies. This evolving narrative ultimately reaffirms the transformative power of combining targeted molecules to overcome the inherent resilience of malignant brain tumors.

Subject of Research: Evaluation of efficacy and safety of anlotinib combined with temozolomide in treatment of recurrent/residual glioma.

Article Title: A retrospective study of 30 cases evaluating the efficacy and safety of anlotinib plus Temozolomide for recurrent/residual glioma from a single center.

Article References:
Xu, L., Yu, D., Li, F. et al. A retrospective study of 30 cases evaluating the efficacy and safety of anlotinib plus Temozolomide for recurrent/residual glioma from a single center. BMC Cancer 25, 1623 (2025). https://doi.org/10.1186/s12885-025-15123-7

Image Credits: Scienmag.com

DOI: https://doi.org/10.1186/s12885-025-15123-7