by Christos Evangelou, MSc, PhD – Medical Writer and Editor

Glioblastoma (GBM) is one of the most challenging cancers to treat, with poor survival outcomes and high recurrence rates. A new study from the University of New Mexico, in collaboration with the University of Mississippi Medical Center and the Medical University of South Carolina, mapped the complex cellular landscape of the subventricular zone (SVZ) in patients with GBM. The researchers identified biological features of residual cancer cells present in the SVZ and potential therapeutic targets that could inform future treatment approaches for this challenging cancer.

The report was published in Cell Reports.

The Subventricular Zone Exhibits a Distinct Microenvironment

The researchers used a fluorescence-guided multiple sampling approach to collect matched tumor mass and SVZ samples from 15 GBM patients, along with two histologically normal SVZ samples as controls. They then employed single-nucleus RNA-sequencing and spatial transcriptomics to create a comprehensive cellular atlas of the SVZ microenvironment.

The spatial data revealed several differences between the tumor mass and the SVZ. Specifically, the study showed that the tumor mass contained all four previously described GBM cell states (astrocyte-like, oligodendrocyte-progenitor-like, mesenchymal-like, and neural-progenitor-like). In contrast, the SVZ lacked the astrocyte-like state. Instead, the SVZ showed enrichment of mesenchymal-like and neural-progenitor-like states, with a distinct ZEB1-centered mesenchymal signature. This cellular composition may contribute to treatment resistance and tumor recurrence, as cancer stem-like cells are known to drive treatment resistance and hijack multiple regulatory mechanisms of normal stem cells, resulting in increased proliferation and self-renewal.

“The identification of a ZEB1-centered mesenchymal signature in the SVZ is important because it uncovers a key mechanism regulating tumor cells in this area,” explained Sara G.M. Piccirillo, PhD, assistant professor at the University of New Mexico, who led this study.

“While our work focuses on the SVZ microenvironment and interactions between tumor cells and other cell types within this microenvironment, this finding also offers the opportunity for future investigations focused on inhibiting ZEB1 and its targets,” she added.

This spatial heterogeneity in GBM extended to the immune compartment as well. Microglia, the resident immune cells of the brain, were more abundant than monocyte-derived macrophages in the SVZ (10.5% vs. 1.7%). However, these two cell types were present in similar proportions in the tumor mass. These microglia displayed a tumor-supportive, inflammatory phenotype, and showed stronger spatial correlations with tumor cells in the SVZ than in the tumor mass.

Microglia-Tumor Cell Crosstalk Provides New Therapeutic Targets

The spatial proximity of microglia and tumor cells in the SVZ prompted the researchers to analyze cellular interactions in the SVZ microenvironment. Using computational tools to predict ligand-receptor interactions, they identified two key signaling pathways, namely IL-1β/IL-1RAcP and Wnt-5a/Frizzled-3, as essential for the interactions between microglia and tumor cells in the SVZ. In addition, spatial transcriptomics analysis revealed that the correlations between microglia and tumor cells were stronger in the SVZ than in the tumor mass.

According to Dr. Piccirillo, these pathways represent potential therapeutic targets for preventing GBM recurrence: “Tumor cells and microglia spatially co-exist in the tissue samples, and IL-1β/IL-1RAcP and Wnt-5a/Frizzled-3 can mediate interactions between them. Given the role of Wnt-5a/Frizzled-3 in cell migration and invasion, we can speculate that through this pathway, SVZ microglia play a role in disease spreading both spatially and temporally, ultimately leading to tumor recurrence.”

In Vitro Validation

To validate these pathways as potential therapeutic targets, the researchers treated patient-derived cells with Nadunolimab, an anti-IL-1RAcP antibody. Inhibition of IL-1β/IL-1RAcP reduced IL-1β secretion by tumor-associated macrophages and inhibited the proliferation of cancer stem-like cells. These effects were more pronounced in cells derived from the SVZ than in cells from the tumor mass.

In addition, inhibition of the Wnt-5a/Frizzled-3 pathway using Box5, a Wnt-5a antagonist, reduced Wnt-5a secretion by tumor-associated macrophages and decreased the invasive capacity of cancer stem-like cells in transwell assays.

“We propose that these two pathways represent potential therapeutic targets in GBM patients based on our results using samples obtained at the time of the initial tumor resection,” Dr. Piccirillo said. “Based on our results, we will perform in vivo experiments using models established by injecting cancer stem-like cells, and we will test the two inhibitors of the IL-1β/IL-1RAcP and Wnt-5a/Frizzled-3 pathways, namely Nadunolimab and Box5.”

To assess the potential clinical relevance of their in vitro findings, the researchers conducted survival analyses using public GBM datasets. They found that high expression of IL1RAP and FZD3 was associated with shorter survival in patients with different GBM subtypes, including mesenchymal and proneural tumors.

Translating Findings to Clinical Applications

Dr. Piccirillo emphasized that their study highlights the importance of targeting residual tumor cells in the SVZ that are typically left behind after surgery. “These areas harbor residual tumor cells responsible for the emergence of the recurrent tumor that is inevitable in GBM patients,” she said.

Dr. Piccirillo’s team is interested in evaluating the therapeutic efficacy of Nadunolimab in patients with GBM. “This drug is currently being tested in multiple clinical trials for several solid cancers,” she said.

Regarding a potential timeline for the clinical translation of their findings, Dr. Piccirillo noted that proposing these markers for patient stratification requires validation across patient datasets and prospective cohorts. “We are currently working on expanding our patient cohort in the context of a multi-PI collaboration,” she added.

The study was supported by The Ben and Catherine Ivy Foundation Translational Adult Glioma Award, The Robert M. Faxon Jr. Endowed Professorship in Neuro-Oncology, NIH grants (P20GM121176, P20GM148302, and P30CA118100), the UNM Comprehensive Cancer Center, the State of New Mexico, the Department of Pathology at UNM, and the Southwest Transformative Educational Advancement and Mentoring Network (NIH R25CA285817-02).

References

1. Licón-Muñoz Y, Avalos V, Subramanian S, et al. Single-nucleus and spatial landscape of the sub-ventricular zone in human glioblastoma. Cell Rep. 2025;44(1):115149. doi:10.1016/j.celrep.2024.115149