Presurgical assessment of cognitive function in pediatric brain tumor patients: feasibility and initial findings.

BACKGROUND: Establishing a presurgical baseline of neurocognitive functioning for pediatric brain tumor patients is a high priority to identify level of functioning prior to medical interventions. However, few studies have obtained adequate samples of presurgery assessments. METHODS: This study examines the feasibility of completing tests to assess pre-surgical neurocognitive functioning in 59 identified pediatric brain tumor patients. RESULTS: Eighty-five percent of patients (n = 50) were referred by the neurosurgery team before surgery and 83% of patients (n = 49) enrolled in the study. A full battery, including both performance-based and parent-report measures of neurocognitive function, was completed for 54% (n = 32) of patients. Rates of completion for either parent-report or performance-based measures were 68% (n = 40) and 69% (n = 41), respectively. While the performance-based assessment fell within the average range (M = 95.4, SD = 14.7, 95% CI, 90.7-100.0), 32% of participants had scores one or more standard deviations below the mean, or twice the expected rate. Parent-reports indicated higher level of concern than the general population (M = 55.4, SD = 11.3, 95% CI, 51.8-59.0) and found that 35% fell one or more standard deviations above the mean, or more than twice the expected rate. CONCLUSIONS: Results suggest it is feasible to conduct pre-surgical assessments with a portion of pediatric brain tumor patients upon diagnosis and these results compare favorably with prior research. However, nearly half of identified patients did not receive a full test battery. Identifying barriers to enrollment and participation in research are discussed as well as recommendations for future research.

Suppression of RAF/MEK or PI3K synergizes cytotoxicity of receptor tyrosine kinase inhibitors in glioma tumor-initiating cells.

BACKGROUND: The majority of glioblastomas have aberrant receptor tyrosine kinase (RTK)/RAS/phosphoinositide 3 kinase (PI3K) signaling pathways and malignant glioma cells are thought to be addicted to these signaling pathways for their survival and proliferation. However, recent studies suggest that monotherapies or inappropriate combination therapies using the molecular targeted drugs have limited efficacy possibly because of tumor heterogeneities, signaling redundancy and crosstalk in intracellular signaling network, indicating necessity of rationale and methods for efficient personalized combination treatments. Here, we evaluated the growth of colonies obtained from glioma tumor-initiating cells (GICs) derived from glioma sphere culture (GSC) in agarose and examined the effects of combination treatments on GICs using targeted drugs that affect the signaling pathways to which most glioma cells are addicted. METHODS: Human GICs were cultured in agarose and treated with inhibitors of RTKs, non-receptor kinases or transcription factors. The colony number and volume were analyzed using a colony counter, and Chou-Talalay combination indices were evaluated. Autophagy and apoptosis were also analyzed. Phosphorylation of proteins was evaluated by reverse phase protein array and immunoblotting. RESULTS: Increases of colony number and volume in agarose correlated with the Gompertz function. GICs showed diverse drug sensitivity, but inhibitions of RTK and RAF/MEK or PI3K by combinations such as EGFR inhibitor and MEK inhibitor, sorafenib and U0126, erlotinib and BKM120, and EGFR inhibitor and sorafenib showed synergy in different subtypes of GICs. Combination of erlotinib and sorafenib, synergistic in GSC11, induced apoptosis and autophagic cell death associated with suppressed Akt and ERK signaling pathways and decreased nuclear PKM2 and ß-catenin in vitro, and tended to improve survival of nude mice bearing GSC11 brain tumor. Reverse phase protein array analysis of the synergistic treatment indicated involvement of not only MEK and PI3K signaling pathways but also others associated with glucose metabolism, fatty acid metabolism, gene transcription, histone methylation, iron transport, stress response, cell cycle, and apoptosis. CONCLUSION: Inhibiting RTK and RAF/MEK or PI3K could induce synergistic cytotoxicity but personalization is necessary. Examining colonies in agarose initiated by GICs from each patient may be useful for drug sensitivity testing in personalized cancer therapy.

Neutrophils promote the malignant glioma phenotype through S100A4.

PURPOSE: Antiangiogenic therapy is effective in blocking vascular permeability, inhibiting vascular proliferation, and slowing tumor growth, but studies in multiple cancer types have shown that tumors eventually acquire resistance to blockade of blood vessel growth. Currently, the mechanisms by which this resistance occurs are not well understood. EXPERIMENTAL DESIGN: In this study, we evaluated the effects of neutrophils on glioma biology both in vitro and in vivo and determined target genes by which neutrophils promote the malignant glioma phenotype during anti-VEGF therapy. RESULTS: We found that an increase in neutrophil infiltration into tumors is significantly correlated with glioma grade and in glioblastoma with acquired resistance to anti-VEGF therapy. Our data demonstrate that neutrophils and their condition media increased the proliferation rate of glioblastoma-initiating cells (GIC). In addition, neutrophils significantly increased GICs Transwell migration compared with controls. Consistent with this behavior, coculture with neutrophils promoted GICs to adopt morphologic and gene expression changes consistent with a mesenchymal signature. Neutrophil-promoting tumor progression could be blocked by S100A4 downregulation in vitro and in vivo. Furthermore, S100A4 depletion increased the effectiveness of anti-VEGF therapy in glioma. CONCLUSIONS: Collectively, these data suggest that increased recruitment of neutrophils during anti-VEGF therapy promotes glioma progression and may promote treatment resistance. Tumor progression with mesenchymal characteristics is partly mediated by S100A4, the expression of which is increased by neutrophil infiltration. Targeting granulocytes and S100A4 may be effective approaches to inhibit the glioma malignant phenotype and diminish antiangiogenic therapy resistance.

Acquired resistance to anti-VEGF therapy in glioblastoma is associated with a mesenchymal transition.

PURPOSE: Antiangiogenic therapy reduces vascular permeability and delays progression but may ultimately promote an aggressive treatment-resistant phenotype. The aim of the present study was to identify mechanisms responsible for glioblastoma resistance to antiangiogenic therapy. EXPERIMENTAL DESIGN: Glioma stem cell (GSC) NSC11 and U87 cell lines with acquired resistance to bevacizumab were developed from orthotopic xenografts in nude mice treated with bevacizumab. Genome-wide analyses were used to identify changes in tumor subtype and specific factors associated with resistance. RESULTS: Mice with established parental NSC11 and U87 cells responded to bevacizumab, whereas glioma cell lines derived at the time of acquired resistance to anti-VEGF therapy were resistant to bevacizumab and did not have prolongation of survival compared with untreated controls. Gene expression profiling comparing anti-VEGF therapy-resistant cell lines to untreated controls showed an increase in genes associated with a mesenchymal origin, cellular migration/invasion, and inflammation. Gene-set enrichment analysis showed that bevacizumab-treated tumors showed a highly significant correlation to published mesenchymal gene signatures. Mice bearing resistant tumors showed significantly greater infiltration of myeloid cells in NSC11- and U87-resistant tumors. Invasion-related genes were also upregulated in both NSC11 and U87 resistant cells which had higher invasion rates in vitro compared with their respective parental cell lines. CONCLUSIONS: Our studies identify multiple proinflammatory factors associated with resistance and identify a proneural to mesenchymal transition in tumors resistant to antiangiogenic therapy.

Glioblastoma resistance to anti-VEGF therapy is associated with myeloid cell infiltration, stem cell accumulation, and a mesenchymal phenotype.

Vascular endothelial growth factor (VEGF) is a critical regulator of angiogenesis. Inhibiting the VEGF-VEGF receptor (R) signal transduction pathway in glioblastoma has recently been shown to delay progression, but the relative benefit and mechanisms of response and failure of anti-VEGF therapy and VEGFR inhibitors are not well understood. The purpose of our study was to evaluate the relative effectiveness of VEGF sequestration and/or VEGFR inhibition on orthotopic tumor growth and the mechanism(s) of treatment resistance. We evaluated, not only, the effects of anti-VEGF therapy (bevacizumab), anti-VEGFR therapy (sunitinib), and the combination on the survival of mice bearing orthotopic gliomas, but also the differential effects of the treatments on tumor vascularity, cellular proliferation, mesenchymal and stem cell markers, and myeloid cell infiltration using flow cytometry and immunohistochemistry. Bevacizumab significantly prolonged survival compared with the control or sunitinib alone. Both antiangiogenic agents initially reduced infiltration of macrophages and tumor vascularity. However, multitargeted VEGFR inhibition, but not VEGF sequestration, rapidly created a vascular gradient and more rapidly induced tumor hypoxia. Re-infiltration of macrophages was associated with the induction of hypoxia. Combination treatment with bevacizumab and sunitinib improved animal survival compared with bevacizumab therapy alone. However, at the time of tumor progression, a significant increase in CD11b(+)/Gr1(+) granulocyte infiltration was observed, and tumors developed aggressive mesenchymal features and increased stem cell marker expression. Collectively, our results demonstrate a more prolonged decrease in tumor vascularity with bevacizumab than with sunitinib, associated with a delay in the development of hypoxia and sustained reduction of infiltrated myeloid cells.