Angiogenesis in meningiomas

Single-cell atlas of the human brain vasculature across development, adulthood and disease

A broad range of brain pathologies critically relies on the vasculature, and cerebrovascular disease is a leading cause of death worldwide. However, the cellular and molecular architecture of the human brain vasculature remains incompletely understood1. Here we performed single-cell RNA sequencing analysis of 606,380 freshly isolated endothelial cells, perivascular cells and other tissue-derived cells from 117 samples, from 68 human fetuses and adult patients to construct a molecular atlas of the developing fetal, adult control and diseased human brain vasculature. We identify extensive molecular heterogeneity of the vasculature of healthy fetal and adult human brains and across five vascular-dependent central nervous system (CNS) pathologies, including brain tumours and brain vascular malformations. We identify alteration of arteriovenous differentiation and reactivated fetal as well as conserved dysregulated genes and pathways in the diseased vasculature. Pathological endothelial cells display a loss of CNS-specific properties and reveal an upregulation of MHC class II molecules, indicating atypical features of CNS endothelial cells. Cell-cell interaction analyses predict substantial endothelial-to-perivascular cell ligand-receptor cross-talk, including immune-related and angiogenic pathways, thereby revealing a central role for the endothelium within brain neurovascular unit signalling networks. Our single-cell brain atlas provides insights into the molecular architecture and heterogeneity of the developing, adult/control and diseased human brain vasculature and serves as a powerful reference for future studies.

Epidemiology, characteristics, and prognostic factors of lymphoplasmacyte-rich meningioma: a systematic literature review

BACKGROUNDS

Lymphoplasmacyte-rich meningioma(LPM) is a rare subtype of meningioma with a low degree of malignancy and an overall preferable prognosis. The purpose of this article is to increase the understanding of the disease, reduce misdiagnosis, and improve prognosis.

METHODS

A search was conducted in the PubMed database for English articles published from 1993 to 2023. The keywords were "lymphoplasmacyte-rich (all fields) and meningioma (all fields) and English (lang)" and "lymphoplasmacyte-rich meningioma (title/abstract) and English (lang)".We further analyzed the clinical manifestations, imaging manifestations, pathological features, treatment strategies, and prognosis of LPM.The possible prognostic indicators were analyzed by the log-rank test and Pearson's chi-squared test.

RESULTS

Fourteen reports with 95 LPM patients were included in this report, including 47 males and 48 females who were diagnosed between the ages of 9 and 79, with an average age of 45 years. The most common clinical manifestations are headache and limb movement disorders. In most cases, the tumor occurred on the convex portion of the brain. All tumors showed significant enhancement, with homogeneous enhancement being more common, and most patients showed peritumoral edema. Postoperative pathological EMA, LCA, and vimentin positivity were helpful for the final diagnosis of the patient. Log-rank tests showed a correlation between complete resection and better prognosis and recurrence.

CONCLUSION

There is a lack of significant differences in the clinical symptoms and imaging manifestations of LPM compared to other diseases that need to be differentiated, and a clear diagnosis requires pathological examination. After standardized surgical treatment, the recurrence rate and mortality rate of LPM are both low. Complete surgical resection of tumors is associated with a better prognosis and lower recurrence rate.

[Factors influencing peritumoral edema in meningiomas: CT- and MRI-based quantitative assessment]

Background. Meningiomas may be accompanied by peritumoral edema. Incidence and pathogenesis of edema are nor clearly established. Prevalence and severity of edema vary significantly in patients with meningiomas similar in various parameters.

OBJECTIVE

To assess peritumoral edema in intracranial meningiomas and factors influencing incidence and severity of this process.

MATERIAL AND METHODS

There were 126 patients (69% women) aged 19-76 years (median 53), who were diagnosed with 142 meningiomas. Patients underwent surgery (n=111) and radiotherapy (n=15) in 2016-2018. The MRI protocol included T1, T2, T2-FLAIR, DWI and post-contrast T1-weighted images in three projections, diffusion tensor MRI in 27 cases and MR spectroscopy in 21 patients.

RESULTS

Peritumoral edema was detected in 46% (n=66) of cases including 21 (31%) patients with severe edema. The ALPS index was 1.510±0.1931 in meningiomas without edema and 1.308±0.19 in those with edema (p=0.014). There was positive correlation between edema, dimensions and uneven contours of meningioma, as well as negative correlation with CSF cleft sign. Blood flow velocity was higher in atypical and anaplastic meningiomas with edema (p=0.03). Other signs (localization, histological variant, malignancy grade, characteristics of MR signal, peaks of the main metabolites, diffusion and perfusion parameters of tumor) did not significantly affect peritumoral edema in patients with meningiomas (p>0.05).

CONCLUSION

Diffusion tensor tomography with ALPS index revealed significant effect of glymphatic system dysfunction on peritumoral edema. Large meningioma with uneven contours increased the risk of peritumoral edema, while CSF cleft sign reduced this risk. Other factors did not affect cerebral edema in meningiomas.

Preoperative surgical risk assessment of meningiomas: a narrative review based on MRI radiomics

Meningiomas are one of the most common intracranial primary central nervous system tumors. Regardless of the pathological grading and histological subtypes, maximum safe resection is the recommended treatment option for meningiomas. However, considering tumor heterogeneity, surgical treatment options and prognosis often vary greatly among meningiomas. Therefore, an accurate preoperative surgical risk assessment of meningiomas is of great clinical importance as it helps develop surgical treatment strategies and improve patient prognosis. In recent years, an increasing number of studies have proved that magnetic resonance imaging (MRI) radiomics has wide application values in the diagnostic, identification, and prognostic evaluations of brain tumors. The vital importance of MRI radiomics in the surgical risk assessment of meningiomas must be apprehended and emphasized in clinical practice. This narrative review summarizes the current research status of MRI radiomics in the preoperative surgical risk assessment of meningiomas, focusing on the applications of MRI radiomics in preoperative pathological grading, assessment of surrounding tissue invasion, and evaluation of tumor consistency. We further analyze the prospects of MRI radiomics in the preoperative assessment of meningiomas angiogenesis and adhesion with surrounding tissues, while pointing out the current challenges of MRI radiomics research.

Differential P-Glycoprotein/CD31 Expression as Markers of Vascular Co-Option in Primary Central Nervous System Tumors

BACKGROUND

Vascular co-option is one of the main features of brain tumor progression. It is identified using histopathological analysis, but no antibody-specific markers were found, and no universally accepted histological features were defined.

METHODS

We employed double immunohistochemical stainings for CD31, P-gp, S100A10, and mitochondria on formalin-fixed, paraffin-embedded human samples of IDH-WT glioblastoma, IDH-mutant astrocytoma, and meningioma to study vascular co-option across different brain tumors and across normal, peritumoral, and intratumoral areas using the Aperio colocalization algorithm, which is a valid and robust method to handle and investigate large data sets.

RESULTS

The results have shown that (i) co-opted vessels could be recognized by the presence of metabolically overactive (evaluated as mitochondria expression) and P-gp⁺ or S100A10⁺ tumor cells surrounding CD31⁺ endothelial cells; (ii) vascular co-option occurs in the intratumoral area of meningioma and astrocytoma; and (iii) vascular co-option is prevalent in peritumoral glioblastoma area.

CONCLUSIONS

The described approach identifies new markers for cellular components of the vessel wall and techniques that uncover the order and localization of vascularization mechanisms, which may contribute to developing new and possibly more effective therapeutic strategies.

Assessment of Serum Hypoxia Biomarkers Pre- and Post-radiotherapy in Patients with Brain Tumors

Hypoxia is a prevalent hallmark of many malignant neoplasms. The aim was to assess the serum hypoxia biomarkers HIF-1α, VEGF, osteopontin, erythropoietin, caveolin-1, GLUT-1, and LDH pre- and post-radiotherapy in patients with brain tumors. The study was conducted on 120 subjects were divided into two groups: group I: 40 healthy volunteers as control group. Group II: 80 brain tumor patients were subdivided into glioblastoma subgroup: 40 glioblastoma patients, meningioma subgroup: 40 malignant meningioma patients. Two venous blood samples were collected from every patient prior to and following RT and one sample from controls. Biomarkers were assayed by ELISA. In glioblastoma subgroup, HIF-1α, VEGF, and LDH were significantly increased after RT. On the contrary, these biomarkers were significantly decreased after RT in malignant meningioma subgroup. Osteopontin was significantly increased after RT in both subgroups. Regarding erythropoietin, it was significantly decreased in both subgroups when compared to before RT. Caveolin-1 showed a significant increase in glioblastoma subgroup after RT comparing to before RT. GLUT-1 was significantly increased after RT in both subgroups comparing to before RT. Association of significant elevation of hypoxia biomarkers either pre- or post-RT with aggressive tumor such as glioblastoma indicates that, they are markers of malignancy and may have a role in tumor development and progression.

Pathologic Characteristics of Pregnancy-Related Meningiomas

Simple Summary

Meningiomas are the most common primary intracranial tumor in adults. Meningiomas are usually benign and slow growing. Treatment is surgical resection in the case of symptomatic growth. Dramatic growth can occur during pregnancy, complicating clinical management and entailing a risk to the well-being of the mother and fetus. Authors of a previous review paper raised the hypothesis that prolactin may be a key contributor to the sudden growth seen in pregnancy-related meningiomas. We set out to investigate the presence of prolactin receptors/prolactin, as well as other female hormones and histopathological characteristics of pregnancy-related meningiomas in Denmark, compared to meningiomas from female controls within the same age group. No differences in hormone receptor distribution were found between the groups and very few meningiomas expressed prolactin receptors, which contradicts the above-mentioned hypothesis. Interestingly, we observed above cut-point proliferative indices of the meningiomas for the entire study population of females in the reproductive age.

Abstract

Meningiomas are the most common intracranial tumor. During pregnancy, explosive growth of a known meningioma occasionally occurs, but the underlying reasons remain unknown. Prolactin has been suggested as a possible key contributor to pregnancy-related meningioma growth. This study sets out to investigate prolactin and prolactin receptor status in 29 patients with pregnancy-related meningiomas in Denmark, from January 1972 to December 2016, as compared to 68 controls aged 20–45 years, also undergoing resection of a meningioma. Furthermore, we investigated potential differences in the progesterone and estrogen receptor statuses, WHO grade, Ki-67 labeling indices, and locations of the resected meningiomas between the cases and controls. Immunohistochemical analyses were performed, and histopathology and intracranial location were assessed with the investigator blinded for the case–control status. None of the samples stained positive for prolactin and very few samples stained positive for prolactin receptors, equally distributed among cases and controls. Estrogen and progesterone receptors generally followed the same distributional pattern between groups, whereas above cut-point Ki-67 labeling indices for both groups were observed. In conclusion, our results did not support the notion of prolactin as a key contributor to pregnancy-related meningioma growth. Rather, the similarities between the cases and controls suggest that meningiomas early in life may comprise a distinct biological entity.

Coexistence of arteriovenous malformation and meningioma in a single patient: Systematic review and illustrative case

BACKGROUND

The coexistence of intracranial arteriovenous malformation (AVM) and meningioma in a single patient is seldom reported, so the clinical profile, optimal management, and outcomes of these patients are mostly unknown.

METHODS

We performed a systematic review of the SCOPUS and PubMed databases for case reports and case series on patients with both intracranial AVMs and meningiomas. Data on demographics, clinical characteristics, surgical management, and outcomes were collected.

RESULTS

A total of 18 cases were reported in the literature, including the present case. The mean age at presentation was 54 years (range of 15-70 years), with no gender predilection. Most of the meningiomas and AVMs were frontal in location, and more than half of the lesions were contiguous. The most common presenting symptoms were seizures (67%), headache (44%), and weakness (33%). Majority of the patients underwent single stage meningioma and AVM excision (44%), followed by staged meningioma excision then AVM excision (17%) and meningioma excision only (17%). In all, 94% (17/18) of the meningiomas were excised compared to 72% (13/18) of the AVMs. Outcomes were reported in 15 patients; 80% were favorable, but there were 2 deaths and 1 tumor recurrence after 5 years.

CONCLUSION

The coexistence of an intracranial AVM with a meningioma is recognized but rarely reported in the literature. Individualized treatment should be employed in managing patients with concurrent lesions, and outcomes are generally favorable due to the benign nature of both these entities.

The relationship between vascular endothelial growth factor and histological grade in intracranial meningioma

Background

Meningioma is the most common benign intracranial neoplasm, accounting for 30% of all primary brain tumors. In 90% of cases, meningiomas are benign. Several aspects of molecular biology, including potential biomarkers, have been studied in attempts to better understand the natural history of meningiomas. Vascular endothelial growth factor (VEGF) is a biomarker responsible for inducing physiological and pathological angiogenesis. VEGF expression has been investigated as a potential predictor of several tumor aspects, including growth rate, recurrence rate, brain tissue invasion, peritumoral edema and surgical prognosis, and also as a marker of histological grade. However, there is no consensus in the literature with respect to the association between this biological factor and meningioma. We digitally analyzed immunohistochemical images using ImageJ software with the aim of correlating VEGF expression with tumor histology.

Methods

Tissue samples from patients presenting with meningioma who had undergone surgical removal between 2007 and 2016 at the Hospital de Clínicas de Porto Alegre (HCPA), in Southern Brazil, were analyzed to identify possible immunohistochemical associations between VEGF and histological grade and subtype.

Results

Seventy-six patients were included; 82% were female, mean age was 59.9 years (range: 18-91). No statistically significant associations were found between VEGF expression and histological grade or subtype (P = 0.310).

Conclusion

Our findings suggest that VEGF is frequently present in meningiomas regardless of histological grade and should not be used as a marker of severity or histological grade.

Clinical Significance of Somatostatin Receptor (SSTR) 2 in Meningioma

Somatostatin receptor (SSTR) 2, widely expressed in meningioma, is a G-protein-coupled receptor and can be activated by somatostatin or its synthetic analogs. SSTR2 is therefore extensively studied as a marker and target for the diagnosis and treatment of meningioma. Accumulating studies have revealed the crucial clinical significance of SSTR2 in meningioma. Summarizing the progress of these studies is urgently needed as it may not only provide novel and better management for patients with meningioma but also indicate the direction of future research. Pertinent literature is reviewed to summarize the recent collective knowledge and understanding of SSTR2’s clinical significance in meningioma in this review. SSTR2 offers novel ideas and approaches in the diagnosis, treatment, and prognostic prediction for meningioma, but more and further studies are required.

The role of caveolin-1 in tumors of the brain - functional and clinical implications

BACKGROUND

Caveolin-1 (cav-1) is the major structural protein of caveolae, the flask-shaped invaginations of the plasma membrane mainly involved in cell signaling. Today, cav-1 is believed to play a role in a variety of disease processes including cancer, owing to the variations of its expression in association with tumor progression, invasive behavior, metastasis and therapy resistance. Since first detected in the brain, a number of studies has particularly focused on the role of cav-1 in the various steps of brain tumorigenesis. In this review, we discuss the different roles of cav-1 and its contributions to the molecular mechanisms underlying the pathobiology and natural behavior of brain tumors including glial, non-glial and metastatic subtypes. These contributions could be attributed to its co-localization with important players in tumorigenesis within the lipid-enriched domains of the plasma membrane. In that regard, the ability of cav-1 to interact with various cell signaling molecules as well as the impact of caveolae depletion on important pathways acting in brain tumor pathogenesis are noteworthy. We also discuss conversant causes hampering the treatment of malignant glial tumors such as limited transport of chemotherapeutics across the blood tumor barrier and resistance to chemoradiotherapy, by focusing on the molecular fundamentals involving cav-1 participation.

CONCLUSIONS

Cav-1 has the potential to pivot the molecular basis underlying the pathobiology of brain tumors, particularly the malignant glial subtype. In addition, the regulatory effect of cav-1-dependent and caveola-mediated transcellular transport on the permeability of the blood tumor barrier could be of benefit to overcome the restricted transport across brain barriers when applying chemotherapeutics. The association of cav-1 with tumors of the brain other than malignant gliomas deserves to be underlined, as well given the evidence suggesting its potential in predicting tumor grade and recurrence rates together with determining patient prognosis in oligodendrogliomas, ependymomas, meningiomas, vestibular schwannomas and brain metastases.

The clinicopathological analysis of receptor tyrosine kinases in meningiomas: the expression of VEGFR-2 in meningioma was associated with a higher WHO grade and shorter progression-free survival

WHO grade II/III meningiomas recur frequently and there is currently no established molecular target therapy for meningioma. No previous studies have revealed the association between receptor tyrosine kinases (RTKs) and the recurrence of meningiomas. This study aims to elucidate the association between RTKs and the clinicopathological characteristics and recurrence of meningioma. We investigated the immunohistochemical expression of RTKs (VEGFR-1/2/3, PDGFR-alpha/beta and c-Kit) in 81 meningiomas (WHO grade I, n = 64, WHO grade II/III, n = 17) in 74 patients. Immunohistochemistry revealed that 29 WHO grade I (45%), 10 WHO grade II (77%), and 4 WHO grade III (100%) tumors were VEGFR-2-positive, and that the VEGFR-2 expression was significantly correlated with the WHO grade. In univariate analyses to investigate the clinicopathological factors associated with recurrence, Simpson grade IV/V resection, a larger tumor size, a high VEGFR-2 expression level, WHO grade II/III, a high Ki-67 expression level, and the non-expression of PgR were identified as significant factors. Furthermore, patients with VEGFR-2-positive meningiomas showed significantly shorter progression-free survival. In the multivariate analysis, WHO grade II/III and the location were significantly associated with recurrence. In conclusion, our study suggests that VEGFR-2 inhibitors might be one of the best candidates for molecular therapy against recurrent meningiomas.

SSTR-2 as a potential tumour-specific marker for fluorescence-guided meningioma surgery

BACKGROUND

Meningiomas are the most frequently occurring primary intracranial tumours in adults. Surgical removal can only be curative by complete resection; however surgical access can be challenging due to anatomical localization and local invasion of bone and soft tissues. Several intraoperative techniques have been tried to improve surgical resection, including intraoperative fluorescence guided imaging; however, no meningioma-specific (fluorescent) targeting has been developed yet. Here, we aimed to identify the most promising biomarkers for targeted intra-operative fluorescence guided meningioma surgery.

METHODS

One hundred forty-eight meningioma specimens representing all meningioma grades were analysed using immunohistochemistry (IHC) on tissue microarrays (TMAs) to determine expression patterns of meningioma biomarkers epithelial membrane antigen (EMA), platelet-derived growth factor β (PDGF-β), vascular endothelial growth factor α (VEGF-α), and somatostatin receptor type 2 (SSTR-2). Subsequently, the most promising biomarker was selected based on TArget Selection Criteria (TASC). Marker expression was examined by IHC in 3D cell culture models generated from freshly resected tumour material.

RESULTS

TMA-IHC showed strongest staining for SSTR-2. All cases were positive, with 51.4% strong/diffuse, 30.4% moderate/diffuse and only 18.2% focal/weak staining patterns. All tested biomarkers showed at least weak positivity in all meningiomas, regardless of WHO grade. TASC analysis showed that SSTR-2 was the most promising target for fluorescence guided imaging, with a total score of 21 (out of 22). SSTR-2 expression was determined on original patient tumours and 3D cultures of three established cultures.

CONCLUSIONS

SSTR-2 expression was highly sensitive and specific in all 148 meningiomas, regardless of WHO grade. According to TASC analysis, SSTR-2 is the most promising receptor for meningioma targeting. After establishing in vitro meningioma models, SSTR-2 cell membrane expression was confirmed in two of three meningioma cultures as well. This indicates that specific fluorescence in an experimental setting can be performed for the further development of targeted fluorescence guided meningioma surgery and near-infrared fluorescent tracers targeting SSTR-2.

Vascular targeting of LIGHT normalizes blood vessels in primary brain cancer and induces intratumoural high endothelial venules

High-grade brain cancer such as glioblastoma (GBM) remains an incurable disease. A common feature of GBM is the angiogenic vasculature, which can be targeted with selected peptides for payload delivery. We assessed the ability of micelle-tagged, vascular homing peptides RGR, CGKRK and NGR to specifically bind to blood vessels in syngeneic orthotopic GBM models. By using the peptide CGKRK to deliver the tumour necrosis factor (TNF) superfamily member LIGHT (also known as TNF superfamily member 14; TNFSF14) to angiogenic tumour vessels, we have generated a reagent that normalizes the brain cancer vasculature by inducing pericyte contractility and re-establishing endothelial barrier integrity. LIGHT-mediated vascular remodelling also activates endothelia and induces intratumoural high endothelial venules (HEVs), which are specialized blood vessels for lymphocyte infiltration. Combining CGKRK-LIGHT with anti-vascular endothelial growth factor and checkpoint blockade amplified HEV frequency and T-cell accumulation in GBM, which is often sparsely infiltrated by immune effector cells, and reduced tumour burden. Furthermore, CGKRK and RGR peptides strongly bound to blood vessels in freshly resected human GBM, demonstrating shared peptide-binding activities in mouse and human primary brain tumour vessels. Thus, peptide-mediated LIGHT targeting is a highly translatable approach in primary brain cancer to reduce vascular leakiness and enhance immunotherapy. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Application of arterial spin labeling perfusion MRI to differentiate benign from malignant intracranial meningiomas

PURPOSE

Differentiating WHO grade I-III of meningioma by non-invasive imaging is challenging. This study investigated the potential of MR arterial spin labeling (ASL) to establish tumor grade in meningioma patients.

MATERIAL AND METHODS

Pseudo-continuous ASL with 3D background suppressed gradient and spin echo (GRASE) was acquired on 54 patients with newly diagnosed or recurrent intracranial meningioma. Perfusion patterns characterized in CBF color maps were independently evaluated by three neuroradiologists blinded to patient history, and correlated with tumor grade from histo-pathological review.

RESULTS

Three perfusion patterns could be discerned by visual evaluation of CBF maps. Pattern 1 consisted of homogeneous hyper-perfusion of the entire tumor; pattern 2 demonstrated heterogeneous hyper-perfusion; pattern 3 showed no substantial hyper-perfusion. Evaluation of the perfusion patterns was highly concordant among the three readers (Kendall W=0.9458, P<0.0001). Pattern 1 was associated with WHO Grade I meningioma of (P<0.0001). Patterns 2 and 3 were predictive of WHO Grade II and III meningioma (P<0.0001), with an odds ratio (OR, versus pattern 1) of 49.6 (P<0.01) in a univariate analysis, and an OR of 186.4 (P<0.01) in a multivariate analysis.

CONCLUSION

Qualitative evaluation of ASL CBF maps can help differentiate benign (WHO Grade I) from higher grade (WHO Grade II and III) intracranial meningiomas, potentially impacting therapeutic strategy.

The Study of MIB-1 LI and CD 34 As A Marker of Proliferative Activity and Angiogenesis in Different Grades of Meningioma

INTRODUCTION

Meningiomas comprise 24-30% of all tumours occurring in the central nervous system. Conventional morphologic critera as studied in routine Haematoxylin and Eosin stained sections (H & E) may not be accurate in grading and assessing prognosis in small stereotactic biopsy specimens. Thus, arises the need for objective methods for assessing tumour biology. Angiogenesis is a key event in the spread of tumours and denotes a poor prognosis. Intratumoural Microvessel Density (MVD) helps in quantification of angiogenesis.

AIM

To measure the proliferative index by MIB-1 and correlate it with the WHO grading of meningiomas. Also to assess the expression of CD34 in various grades of meningioma and evaluate their angiogenic potential by calculating MVD.

MATERIALS AND METHODS

Paraffin blocks of 30 surgically resected cases, 10 each of grade I, II and III meningiomas were reviewed. Tumours were graded and subtyped as per WHO criteria. Immunohistochemical staining was done with MIB-1 and CD 34 antibodies. Statistical analysis was performed using Mann - Whitney U test. p-value of < 0.05 was considered significant.

RESULTS

The male to female ratio overall was 1:1. The age of the patients ranged from 18-81 years. A 73% of patients had raised intracranial pressure and 18.4% of patients presented with seizures. The mean ± SD MIB-1 LI was 1.14 ± 0.84, 8.94 ± 2.73 and 35.62 ± 4.44 in grade I, II and III tumours respectively which was statistically significant. (p< 0.01). The mean ± SD MVD was 49.67 ± 22.35, 41.37 ± 7.45 and 47.86 ± 10.77 respectively in grade I, II and III tumours (p NS).

CONCLUSION

MIB-1 LI is an important complementary tool to accurately grade meningothelial tumours and assess tumour biology. Specific cycling endothelial markers along with CD 34 & MVD could be used to assess the prognosis of these tumours.

Perfusion computed tomography of intracranial meningiomas: In vivo correlation of cerebral blood volume and vascular permeability

BACKGROUND

A noninvasive method to predict the grade of a meningioma would be desirable since it would anticipate information about tumour nature, recurrence and improve tumour management and outcomes. The aim of the present study was to assess the ability of perfusion computed tomography (PCT) technique in predicting the meningioma grade before surgery. Data from PCT, such as cerebral blood volume (CBV) and permeability surface (PS), were correlated with immunohistolopathological information.

METHODS

Twenty-three patients with a diagnosis of intracranial meningioma underwent PCT for pre-surgical evaluation of CBV and PS. During surgery, samples from the centre and periphery of the tumour were obtained. Two correspondent regions of interest (ROIs) were drawn on CBV and PS maps. Central and peripheral CBV and PS mean values were calculated. PCT parameters were correlated to CD-34 and endoglin.

RESULTS

There was a positive correlation between PS and CD-34. No correlation was found between PS values and endoglin, CBV values and CD-34 and endoglin values.

CONCLUSION

Our findings suggest that PCT may support conventional morphological imaging in predicting meningioma grading before surgery.

The density of microvessels positive for Wilms' tumour-1 protein (WT-1) is an independent predictor of recurrence risk in meningiomas

Wilms' tumour-1 (WT-1) protein m-RNA was recently demonstrated in meningiomas, suggesting the potential application of WT-1 immunotherapy in these tumours. The aim of the present study was to analyze the immunohistochemical expression of WT-1 protein, its correlation with the clinico-pathological variables and association with vascular endothelial growth factor (VEGF) expression, in a series of 60 meningiomas of different histotype and histological grade. None of the cases expressed WT-1 in the neoplastic cells, while endothelial expression was evidenced in a variable number of tumour vessels in all the meningiomas. The density of microvessels positive for WT-1 (WT-1 MVD) was significantly higher in meningiomas showing higher histological grade (P = 0.0191), growth fraction (P = 0.0201), expression of VEGF (P = 0.0288) and recurrence risk (P = 0.022). In addition, high WT-1 MVD was a significant independent predictive factor for a shorter recurrence-free survival (RFS) in patients with completely resected meningiomas (P = 0.0028). In conclusion, this study shows that WT-1 MVD is correlated with the biological aggressiveness of meningiomas. Although no staining for WT-1 was evidenced in the neoplastic cells of these tumours, WT-1 endothelial expression in the tumour vessels might represent a target for WT-1 immunotherapy in the aim of reducing their blood supply and growth.

p-CREB expression in human meningiomas: correlation with angiogenesis and recurrence risk

Despite total surgical resection, a percentage of meningiomas do unexpectedly recur. At present the prediction of recurrence risk and the management of recurrent tumours represent major issues in the patients affected by meningiomas. The present study aims at investigating the prognostic value of the expression of the phosphorylated transcription factor cyclic AMP responsive element binding protein (p-CREB) in a series of meningiomas of different histotype and grade. While no p-CREB expression was found in specimens of normal leptomeninges, 71 % of meningiomas in our cohort expressed p-CREB. In addition, nuclear expression of p-CREB was present in the endothelia of tumor vessels in all of the meningiomas, but not in the vessels of the non-neoplastic meninges. High expression of p-CREB was significantly more frequent in meningiomas showing atypical, chordoid or microcystic histotype (P = 0.0003), high histological grade (P < 0.0001), high Ki-67 labeling index (P = 0.0001), high microvessel density counts (P < 0.0001) and high vascular endothelial growth factor expression (P = 0.0113). In addition, high p-CREB expression was significantly associated with the development of recurrences (P = 0.0031) and it was a significant negative, albeit not independent, prognostic factor for disease free survival in patients with meningiomas submitted to complete surgical removal (P = 0.0019). In conclusion, we showed that p-CREB is expressed in human meningiomas and that it represents a significant predictor of recurrence risk in these tumors. Due to its high expression in more aggressive tumors and in the tumor vessels, it may represent a novel therapeutic target in meningiomas.

Phase II trial of sunitinib for recurrent and progressive atypical and anaplastic meningioma

BACKGROUND

No proven effective medical therapy for surgery and radiation-refractory meningiomas exists. Sunitinib malate (SU011248) is a small-molecule tyrosine kinase inhibitor that targets vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor, abundant in meningiomas.

METHODS

This was a prospective, multicenter, investigator-initiated single-arm phase II trial. The primary cohort enrolled patients with surgery and radiation-refractory recurrent World Health Organization (WHO) grades II-III meningioma. An exploratory cohort enrolled patients with WHO grade I meningioma, hemangiopericytoma, or hemangioblastoma. Sunitinib was administered at 50 mg/d for days 1-28 of every 42-day cycle. The primary endpoint was the rate of 6-month progression-free survival (PFS6), with secondary endpoints of radiographic response rate, safety, PFS, and overall survival. Exploratory objectives include analysis of tumoral molecular markers and MR perfusion imaging.

RESULTS

Thirty-six patients with high-grade meningioma (30 atypical and 6 anaplastic) were enrolled. Patients were heavily pretreated (median number of 5 recurrences, range 2-10). PFS6 rate was 42%, meeting the primary endpoint. Median PFS was 5.2 months (95% CI: 2.8-8.3 mo), and median overall survival was 24.6 months (95% CI: 16.5-38.4 mo). Thirteen patients enrolled in the exploratory cohort. Overall toxicity included 1 grade 5 intratumoral hemorrhage, 2 grade 3 and 1 grade 4 CNS/intratumoral hemorrhages, 1 grade 3 and 1 grade 4 thrombotic microangiopathy, and 1 grade 3 gastrointestinal perforation. Expression of VEGFR2 predicted PFS of a median of 1.4 months in VEGFR2-negative patients versus 6.4 months in VEGFR2-positive patients (P = .005).

CONCLUSION

Sunitinib is active in recurrent atypical/malignant meningioma patients. A randomized trial should be performed.

Peritumoral brain edema in intracranial meningiomas: the emergence of vascular endothelial growth factor-directed therapy

Meningioma is the second most common type of adult intracranial neoplasm. A substantial subset of patients present with peritumoral brain edema (PTBE), which can cause significant morbidity via mass effect, complicate surgical management, and impact the safety of stereotactic radiosurgery. Recent studies suggest a close relationship between vascular endothelial growth factor-A (VEGF-A) expression and PTBE development in meningiomas. The authors performed a systematic review of the literature on the pathogenesis of PTBE in meningiomas, the effectiveness of steroid therapy, the role played by VEGF-A, and the current clinical evidence for antiangiogenic therapy to treat peritumoral brain edema. Mounting evidence suggests VEGF-A is secreted directly by meningioma cells to induce angiogenesis and edemagenesis of tumoral as well as peritumoral brain tissue. The VEGF-A cascade results in recruitment of cerebral-pial vessels and disruption of the tumor-brain barrier, which appear to be requisite for VEGF-A to have an edemagenic effect. Results of preliminary clinical studies suggest VEGF-directed therapy has modest activity against recurrent and progressive meningioma growth but can alleviate PTBE in some patients. A comprehensive understanding of the VEGF-A pathway and its modulators may hold the key to an effective therapeutic approach to treating PTBE associated with meningiomas. Further clinical trials with larger patient cohorts and longer follow-up periods are warranted to confirm the efficacy of VEGF-directed therapy.

Immuno-expression of endoglin and smooth muscle actin in the vessels of brain metastases. Is there a rational for anti-angiogenic therapy?

Despite ongoing clinical trials, the efficacy of anti-angiogenic drugs for the treatment of brain metastases (BM) is still questionable. The lower response rate to anti-angiogenic therapy in the presence of BM than in metastatic disease involving other sites suggests that BM may be insensitive to these drugs, although the biological reasons underlining this phenomenon are still to be clarified. With the aim of assessing whether the targets of anti-angiogenic therapies are actually present in BM, in the present study, we analyzed the microvessel density (MVD), a measure of neo-angiogenesis, and the vascular phenotype (mature vs. immature) in the tumor tissue of a series of BM derived from different primary tumors. By using immunohistochemistry against endoglin, a specific marker for newly formed vessels, we found that neo-angiogenesis widely varies in BM depending on the site of the primary tumor, as well as on its histotype. According to our results, BM from lung cancer displayed the highest MVD counts, while those from renal carcinoma had the lowest. Then, among BM from lung cancer, those from large cell and adenocarcinoma histotypes had significantly higher MVD counts than those originating from squamous cell carcinoma (p = 0.0043; p = 0.0063). Of note, MVD counts were inversely correlated with the maturation index of the endoglin-stained vessels, reflected by the coverage of smooth muscle actin (SMA) positive pericytes (r = −0.693; p < 0.0001). Accordingly, all the endoglin-positive vessels in BM from pulmonary squamous cell carcinoma and renal carcinoma, displayed a mature phenotype, while vessels with an immature phenotype were found in highly vascularized BM from pulmonary large cell and adenocarcinoma. The low MVD and mature phenotype observed in BM from some primary tumors may account for their low sensitivity to anti-angiogenic therapies. Although our findings need to be validated in correlative studies with a clinical response, this should be taken into account in therapeutic protocols in order to avoid the adverse effects of useless therapies.

Gamma knife radiosurgery inhibits angiogenesis of meningiomas: in vivo rat corneal assay

OBJECTIVE

The aim of this study is to reveal inhibitory effect of gamma knife irradiation on angiogenesis of meningiomas using rat corneal angiogenesis assay.

METHODS

A total of 72 rats were divided into three preliminary groups. Each group, consisting of 24 rats, was implanted to World Health Organization (WHO) grade I (typical), grade II (atypical), and grade III (malignant) meningioma. Each of these three preliminary groups of 24 rats, were then divided into four subgroups, each consisting of 6 rats and subsequently irradiated by gamma knife with dose prescriptions of 0, 14, 18, and 22 Gy. The numbers of vessels that developed around the micropockets of the corneas were counted and photographed on days 5, 10, 15, and 20.

RESULTS

For WHO grade I meningiomas, 18 and 22 Gy doses (P < 0.001), and for grade II meningiomas, the 22-Gy (P = 0.021) dose were found to inhibit tumor-induced angiogenesis compared with the radiation-free control group. For grade III meningiomas, there was no statistical difference with the control group in any of the doses applied. Our findings demonstrate that gamma knife irradiation may suppress the angiogenic activity of WHO grades I and II meningiomas but not of the grade III meningiomas.

CONCLUSIONS

For the first time, this study provides an experimental data to show the antiangiogenic effect of gamma knife irradiation on meningiomas.

NDRG4, the N-Myc downstream regulated gene, is important for cell survival, tumor invasion and angiogenesis in meningiomas

Meningiomas are the second most common brain tumor, and 20-30% of these tumors are aggressive. The aggressive subtypes are characterized by a capacity for invasion of normal brain with frequent and destructive recurrence patterns. Effective local therapies include surgery and radiation, but there is a need for novel molecular targets to improve survival and reduce morbidity for this group or cancer patients. We have recently identified the N-Myc downstream regulated gene 4, NDRG4, protein as being overexpressed in aggressive meningioma, and in this report, demonstrate its role in cell survival, invasion/migration and angiogenesis. Downregulation of NDRG4 mRNA and protein expression in two high-grade meningioma cancer cell lines, IOMM-Lee and CH-157 MN resulted in reduction in cell survival, DNA fragmentation and G2-M cell cycle arrest. NDRG4 downregulation also decreased cellular invasion and migration, as determined by spheroid migration, linear and radial wound healing, Boyden chamber matrigel invasion, and 3D invasion assays. To determine the effect of NDRG4 depletion on angiogenesis, we studied the immortalized brain endothelial cell line, bEnd.3. We treated bEnd.3 cells with conditioned media from NDRG4-depleted IOMM-Lee and CH-157 MN cells and abrogated their ability to elicit bEnd.3 capillary-like tubes, to proliferate, and to invade. NDRG4 is not overexpressed in bEnd.3 cells and direct NDRG4 depletion had no effect on the cells. This study is significant as it is the first to demonstrate the functional role of NDRG4 in various aspects of meningioma tumor biology. NDRG4 is involved in modulating cell proliferation, invasion, migration and angiogenesis in meningioma, and may play a valuable role as a molecular target in its treatment.

Peritumoral brain edema in angiomatous supratentorial meningiomas: an investigation of the vascular endothelial growth factor A pathway

The aim of this work was to study the vascular endothelial growth factor A (VEGF-A) pathway and peritumoral brain edema (PTBE) through comparison of non-angiomatous and angiomatous meningiomas. Meningiomas are common intracranial tumors, which often have PTBE. VEGF-A is an integral part of PTBE formation and angiogenesis, and the capillary-rich angiomatous meningiomas are known for their PTBE. The VEGF-A receptor VEGFR-2 is responsible for the angiogenic effect of VEGF-A on endothelial cells, which is enhanced by the co-receptor neuropilin-1. Forty non-angiomatous, 22 angiomatous meningiomas, and 10 control tissue samples were collected for the study. Magnetic resonance images were available for 40 non-angiomatous and 10 angiomatous meningiomas. Tissue sections were immunostained for CD34, MIB-1, estrogen- and progesterone receptors. ELISA, chemiluminescence, and RT-qPCR were used for VEGF-A, VEGFR-2, and neuropilin-1 protein and mRNA quantification. Angiomatous meningiomas had larger PTBE (695 vs 218 cm(3) , p = 0.0045) and longer capillary length (3614 vs 605 mm/mm(3) , p < 0.0001). VEGF-A mRNA, neuropilin-1 mRNA, and VEGFR-2 protein levels were higher in angiomatous meningiomas independently of the capillary length (p < 0.05). Neuropilin-1 protein levels were lower in angiomatous meningiomas (p < 0.0001). The VEGF-A pathway and tumor capillary length may be essential for PTBE-formation in meningiomas. Further investigations of this pathway could lead to earlier therapy and targeted pharmacological treatment options.

Correlation between dynamic contrast-enhanced perfusion MRI relative cerebral blood volume and vascular endothelial growth factor expression in meningiomas

PURPOSE

To determine whether there is a correlation between vascular endothelial growth factor (VEGF) expression and cerebral blood flow (CBV) measurements in dynamic contrast-enhanced susceptibility perfusion magnetic resonance imaging (MRI) and to correlate the perfusion characteristics in high- versus low-grade meningiomas.

METHODS AND MATERIALS

A total of 48 (24 high-grade and 24 low-grade) meningiomas with available dynamic susceptibility-weighted MRI were retrospectively reviewed for maximum CBV and semiquantitative VEGF immunoreactivity. Correlation between normalized CBV and VEGF was made using the Spearman rank test and comparison between CBV in high- versus low-grade meningiomas was made using the Wilcoxon test.

RESULTS

There was a significant (P = .01) correlation between normalized maximum CBV and VEGF scores with a Spearman correlation coefficient of 0.37. In addition, there was a significant (P < .01) difference in normalized maximum CBV ratios between high-grade meningiomas (mean 12.6; standard deviation 5.2) and low-grade meningiomas (mean 8.2; standard deviation 5.2).

CONCLUSION

The data suggest that CBV accurately reflects VEGF expression and tumor grade in meningiomas. Perfusion-weighted MRI can potentially serve as a useful biomarker for meningiomas, pending prospective studies.