Application of oncogenetic trees mixtures as a biostatistical model of the clonal cytogenetic evolution of meningiomas

The Evolving Classification of Meningiomas: Integration of Molecular Discoveries to Inform Patient Care

Meningioma classification and treatment have evolved over the past eight decades. Since Bailey, Cushing, and Eisenhart's description of meningiomas in the 1920s and 1930s, there have been continual advances in clinical stratification by histopathology, radiography and, most recently, molecular profiling, to improve prognostication and predict response to therapy. Precise and accurate classification is essential to optimizing management for patients with meningioma, which involves surveillance imaging, surgery, primary or adjuvant radiotherapy, and consideration for clinical trials. Currently, the World Health Organization (WHO) grade, extent of resection (EOR), and patient characteristics are used to guide management. While these have demonstrated reliability, a substantial number of seemingly benign lesions recur, suggesting opportunities for improvement of risk stratification. Furthermore, the role of adjuvant radiotherapy for grade 1 and 2 meningioma remains controversial. Over the last decade, numerous studies investigating the molecular drivers of clinical aggressiveness have been reported, with the identification of molecular markers that carry clinical implications as well as biomarkers of radiotherapy response. Here, we review the historical context of current practices, highlight recent molecular discoveries, and discuss the challenges of translating these findings into clinical practice.

Noncoding RNA landscape and their emerging roles as biomarkers and therapeutic targets in meningioma

Meningiomas are among the most prevalent primary CNS tumors in adults, accounting for nearly 38% of all brain neoplasms. The World Health Organization (WHO) grade assigned to meningiomas guides medical care in patients and is primarily based on tumor histology and malignancy potential. Although often considered benign, meningiomas with complicated histology, limited accessibility for surgical resection, and/or higher malignancy potential (WHO grade 2 and WHO grade 3) are harder to combat, resulting in significant morbidity. With limited treatment options and no systemic therapies, it is imperative to understand meningioma tumorigenesis at the molecular level and identify novel therapeutic targets. The last decade witnessed considerable progress in understanding the noncoding RNA landscape of meningioma, with microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) emerging as molecular entities of interest. This review aims to highlight the commonly dysregulated miRNAs and lncRNAs in meningioma and their correlation with meningioma progression, malignancy, recurrence, and radioresistance. The role of "key" miRNAs as biomarkers and their therapeutic potential has also been reviewed in detail. Furthermore, current and emerging therapeutic modalities for meningioma have been discussed, with emphasis on the need to identify and subsequently employ clinically relevant miRNAs and lncRNAs as novel therapeutic targets and biomarkers.

Risk factors on surgical compliance and its impact on survival outcomes in meningioma patients: a SEER-based retrospective propensity-score matched analysis

BACKGROUND

This study aimed to analyze the effect of surgical compliance on the survival outcome of patients with meningioma and explore the factors affecting surgical compliance.

METHODS

We selected data from the Surveillance, Epidemiology, and End Results database for 122,632 meningioma patients diagnosed between 2004 and 2018. The effect of surgical compliance on patients' overall survival (OS) was analyzed through Cox regression and Kaplan-Meier curves. Independent risk factors for surgical compliance were identified through multifactorial logistic regression analyses to construct diagnostic nomograms, further assessed by receiver operating characteristic curves. Furthermore, we used univariate and multivariate logistic regression analyses to evaluate relevant variables linked to adherence with meningioma surgery. Moreover, 1:1 propensity score matching was applied to assess the validity of the results in patients with favorable and poor surgical compliance.

RESULTS

A total of 48,735 were eligible from the initial cohort of 122,632 patients with meningioma. Among them, 45,038 (92.40%) exhibited good surgical compliance, while 3697 (7.60%) had poor surgical compliance. The rate of patients with good surgical compliance was significantly higher than that of patients with inadequate surgical compliance (p < 0.001). Moreover, surgical compliance is an independent prognostic factor for OS in meningioma patients. Univariate Cox regression analysis indicated that individuals with poor surgical compliance demonstrated lower OS rates than those with good surgical compliance (hazard ratio [HR 2.404; 95% confidence interval [CI] 2.276-2.54, p < 0.001], consistent with the observation in the multivariate analysis (HR 1.564; 95% CI 1.471-1.663, p < 0.001). We developed a prediction model using seven variables: age, sex, race, tumor behavior recode, tumor size, family income, and residential setting (p < 0.05). Surgical compliance was associated with patient age, sex, race, tumor behavior recode, tumor size, family income, and residential setting by logistic regression analysis.

CONCLUSIONS

Surgical compliance emerged as an independent prognostic factor for survival in patients with meningioma. Poor surgical compliance was associated with older age, black and other races, females, advanced-stage tumors, larger tumor size, lower household income, and rural residence. When patients experienced these conditions, OS was shorter, requiring more aggressive treatment.

Prognostic Factors Affecting Postsurgical Outcomes of Adult Patients with Intracranial Meningioma: A Retrospective Study

OBJECTIVE

To identify the prognostic factors of surgical resection for meningioma and their relationship with patient outcomes.

METHODS

This retrospective study included 53 patients (≥16 years), who underwent surgical resection for intracranial meningioma at the King Abdulaziz University Hospital from 2012 to 2022. Data regarding tumor location and size, histopathological type, chief complaint, chief complaint duration, admission date, diagnosis, operation, and discharge date were collected. These data were subjected to univariate and bivariate analyses to investigate the relationship between the postsurgical outcomes of the patients with meningioma and the variables of age at surgery, sex, length of hospitalization, chief complaint, Glasgow outcome score, World Health Organization histopathological classification, body mass index, tumor size, and nature of surgical resection.

RESULTS

The mean age of our study cohort was 49.09 ± 12.64 years, with a female preponderance (75.5%) and mean body mass index of 29.31 ± 5.52 kg/m2. length of hospitalization (mean: 26.92 ± 54.88 days) demonstrated a significant (P = 0.012) impact on prognosis after surgery. In addition, convexity meningiomas (21.2%), which were observed in the maximum number of cases, and mean tumor volume (28.67 ± 48.85 mm) were significantly (P = 0.049) associated with the outcome. Most patients (78.8%) underwent total surgical resection, and histopathological examinations revealed a higher frequency of grade 1 than grade 2 tumors.

CONCLUSIONS

Short duration of hospitalization and superficial location of the tumor are associated with optimal outcomes after surgical resection for patients with meningioma.

MicroRNA 200a as a histologically independent marker for meningioma recurrence: Results of a four microRNA panel analysis in meningiomas

INTRODUCTION

Meningiomas are mostly benign neoplasms of the central nervous system. Nevertheless there are recurrences in about 20% after surgical resection. Previous studies could reveal several predictors of meningioma recurrence. Tumor progression often is associated with a specific pattern of chromosome losses. Our study investigated the potential function of selected microRNAs as markers of tumor progression.

METHODS

By real-time polymerase chain reaction the expressions of microRNA 21-3p, 34a-3p, 200a-3p, and 409-3p were analyzed in solid tumor and in blood samples of 51 meningioma patients as well as in blood samples of 20 healthy individuals. Additionally, aberrations of parts of chromosomes 1, 14, 18, and 22 were analyzed by FISH. Tumor and blood samples were statistically analyzed, using Spearman's rank correlation coefficient as well as Mann-Whitney U- and Kruskal-Wallis-Test.

RESULTS

MicroRNA 200a showed significantly lower expressions in recurrent meningiomas than in newly diagnosed ones. MicroRNA 409 in meningiomas was correlated significantly with tumor volume and showed a significant negative correlation with patient age. Significance was found between the expression patterns of microRNAs 34a and 200a with the respective aberrations of chromosome 1p and the microRNA 409 with aberration of chromosome 14. In the male cohort the expression of microRNA 200a in blood was significantly upregulated in patients compared to healthy volunteers. By our research the function of microRNA 200a was proved to detect meningioma patients by liquid biopsy.

CONCLUSION

We detected microRNA 200a as a new biomarker to indicate meningioma recurrences. Future transferability to blood could be important for patient follow-up.

Incidence and Survival of Benign, Borderline, and Malignant Meningioma Patients in the United States from 2004 to 2018

Meningioma is the most common primary central nervous system tumor, and its incidence is increasing. A systematic epidemiological and clinical analysis is required to better estimate its public health impact and understand its prognostic factors. Data were obtained from the Surveillance, Epidemiology, and End Results (SEER) database from 2004 to 2018 for all types of meningiomas without an age restriction. Age-adjusted incidence rates (IRs) and 95% confidence intervals were estimated according to sex, age, race, ethnicity, and tumor location. Kaplan-Meier analysis and multivariate Cox proportional hazard models were used to analyze the overall survival (OS). The competing risk regression model of Fine-Gray was used to analyze cause-specific survival. Data from a total of 109,660 meningioma patients were analyzed. A majority of patients were older than 60 years, and only 0.41% of patients were 0-19 years. The meningioma IRs were higher in females, Black, and non-Hispanic patients than in males, White, and Hispanic patients, respectively, and IRs increased with age. The ratio of IRs for females to males was 2.1 and also increased with age, peaking at 3.6 in the 45-49-year-old group. Older and male patients with all types of meningiomas, Black patients with benign and borderline meningiomas, and patients with larger borderline and malignant meningiomas showed poorer prognosis. For all meningioma types, surgical resection improved survival. The reported incidence rates and survival trends covered all demographics and subtypes of meningiomas. Older age, male sex, Black race, and tumor size may be important prognostic factors for meningioma cases, and tumor resection can substantially improve survival among meningioma patients.

Integrated Molecular-Morphologic Meningioma Classification: A Multicenter Retrospective Analysis, Retrospectively and Prospectively Validated

PURPOSE

Meningiomas are the most frequent primary intracranial tumors. Patient outcome varies widely from benign to highly aggressive, ultimately fatal courses. Reliable identification of risk of progression for individual patients is of pivotal importance. However, only biomarkers for highly aggressive tumors are established (CDKN2A/B and TERT), whereas no molecularly based stratification exists for the broad spectrum of patients with low- and intermediate-risk meningioma.

METHODS

DNA methylation data and copy-number information were generated for 3,031 meningiomas (2,868 patients), and mutation data for 858 samples. DNA methylation subgroups, copy-number variations (CNVs), mutations, and WHO grading were analyzed. Prediction power for outcome was assessed in a retrospective cohort of 514 patients, validated on a retrospective cohort of 184, and on a prospective cohort of 287 multicenter cases.

RESULTS

Both CNV- and methylation family-based subgrouping independently resulted in increased prediction accuracy of risk of recurrence compared with the WHO classification (c-indexes WHO 2016, CNV, and methylation family 0.699, 0.706, and 0.721, respectively). Merging all risk stratification approaches into an integrated molecular-morphologic score resulted in further substantial increase in accuracy (c-index 0.744). This integrated score consistently provided superior accuracy in all three cohorts, significantly outperforming WHO grading (c-index difference P = .005). Besides the overall stratification advantage, the integrated score separates more precisely for risk of progression at the diagnostically challenging interface of WHO grade 1 and grade 2 tumors (hazard ratio 4.34 [2.48-7.57] and 3.34 [1.28-8.72] retrospective and prospective validation cohorts, respectively).

CONCLUSION

Merging these layers of histologic and molecular data into an integrated, three-tiered score significantly improves the precision in meningioma stratification. Implementation into diagnostic routine informs clinical decision making for patients with meningioma on the basis of robust outcome prediction.

Incidence, survival and geoepidemiological analysis of meningiomas and glioblastomas in the province of Catania during the 2003-2016 period

BACKGROUND

Meningiomas are the most common primary brain tumors, followed by glioblastomas. Nevertheless, no previous studies have been conducted to evaluate the epidemiology of meningiomas and glioblastomas in the southern region of Italy. Thus, the aim of our study was to evaluate incidence, temporal trend and survival rate of meningiomas and glioblastomas in the province of Catania during the study period. Moreover, a geoepidemiological analysis was performed in order to identify possible geographical and temporal clusters.

METHODS

All subjects with meningiomas and glioblastomas diagnosed from 2003 to 2016 in the province of Catania were collected, using the local cancer registry. Incidence rate (IR) was calculated by gender, age-groups and tumor behavior. Temporal changes in incidence trend were assessed using a Joinpoint regression analysis while survival analysis was performed using Kaplan-Meier method. Cluster analysis was performed using Kulldorff's spatial scan statistic.

RESULTS

In the province of Catania, a total of 1488 cases of meningiomas and 443 cases of glioblastomas were identified from 2003 to 2016, with an IR of 9.8/100,000 person-years (95%CI 9.3-10.3) and 2.9/100,000 person-years (95%CI 2.7-3.2), respectively. Meningiomas were more common among women (p-value<0.0001), while glioblastomas among men (p-value<0.0001). IR progressively increased over the ages, reaching a peak in the 75-84 and 65-74 years-old group in, respectively, meningiomas and glioblastomas. Mean survival was higher in subjects diagnosed with meningiomas as compared to those with glioblastomas (10.7 years and 15.8 months, respectively), with age as the strongest risk factor for death. Spatial and space-time cluster of high incidence of meningiomas was detected in a small community on the eastern flank of the Mt. Etna volcano.

CONCLUSIONS

Epidemiology of meningioma and glioblastoma in the province of Catania is close to that reported worldwide. Spatial and space-time cluster of meningiomas were found in Pedara. Further studies on risks factor are necessary.

Fluorescence image-guided resection of intracranial meningioma: an experimental in vivo study on nude mice

INTRODUCTION

The use of photodynamic agents in malignant cranial tumor surgery is quite common. For example five-aminolevulinic acid (5-ALA)-induced porphyrins in malignant gliomas are potent photosensitizers. Until today there is no comparable selective fluorescent substance available for meningiomas. Nevertheless, there is a demand for intraoperative fluorescent identification of e.g. invasive skull base meningiomas to increase radicality. This study was established to investigate fluorescent image-guided resection with somatostatin receptor labelled fluorescence dye for intracranial meningioma in the nude mice.

METHODS

Primary meningioma cell culture samples were stereotactically implanted subdural into 20 nude mice. 90 days after inoculation of the cells, a cranial MRI with contrast agent revealed tumor growth. After detection of tumor mass in MRI, FAM-TOC5,6-Carboxyfluoresceine-Tyr3-Octreotide was injected intravenously and tumor mass was hereafter resected under visualization via fluorescence microscope and endoscope. After attempted total resection, animal were sacrificed brain slices were obtained and histologically analysed to verify the resection extent.

RESULTS

In 18 mice tumor growth was detected in MRI after 90 days of inoculation. The tumor mass could be clearly identified with fluorescence microscope and endoscope after injecting FAM-TOC5,6-Carboxyfluoresceine-Tyr3-Octreotide. The tumor margins could be better visualized. After fluorescence-guided resection no remaining tumor could be identified in histological analysis.

CONCLUSIONS

This study describes for the first time the use of FAM-TOC5,6-Carboxyfluoresceine-Tyr3-Octreotide and demonstrates its value of fluorescent identification of meningioma cells in vivo. Furthermore, the authors established a new experimental animal model for fluorescence meningioma surgery.

Rapid Intraoperative Diagnosis of Meningiomas using Stimulated Raman Histology

BACKGROUND

Frozen section is a time- and labor-intensive method for intraoperative pathologic diagnosis. As a result, there exists a need to expedite and streamline the acquisition and interpretation of diagnostic histologic data to inform surgical decision making. Stimulated Raman histology (SRH) is an emerging technology that may serve to expedite the acquisition and interpretation of histologic data in the operating room.

METHODS

A blinded, prospective cohort study of 82 patients undergoing resection for tumors of the central nervous system was performed. Twenty-six patients with diagnoses of meningioma on SRH, frozen, or permanent section were included in this subanalysis. Diagnostic time and accuracy of stimulated SRH histology images were compared with the gold standard (frozen section). Agreement of SRH and frozen section diagnosis with permanent section (true) diagnosis was also compared.

RESULTS

Mean time-to-diagnosis was significantly shorter for SRH-mediated diagnosis compared with frozen section (9.2 vs. 35.8, P < 0.0001). Diagnostic accuracy was not significantly different between methods (P = 0.15). Diagnostic agreement was not significantly different between SRH versus frozen, SRH versus permanent, or frozen versus permanent section methods (P = 0.5, P = 0.5, P = 1.00).

CONCLUSIONS

SRH is a promising adjuvant technology that may expedite intraoperative neuropathologic consult without sacrificing diagnostic accuracy.

Meningiomas: An Overview of the Landscape of Copy Number Alterations in Samples from an Admixed Population

Meningiomas are considered the most common intracranial tumors, affecting mainly women. Studies in mixed populations can be of great importance to clarify issues related to the genetic diversity of tumors and their development. Considering that data obtained from analyses of the profile of copy number alterations (CNA) have been a useful diagnostic indicator for many types of tumors and that meningiomas show a complex pattern of gains and losses in the number of copies, our objective was to analyze the CNA profile in 33 samples of meningiomas of different histological grades (WHO Grade I-III) from patients in a city located in the Amazon region of Brazil, using aCGH. We found that the female to male ratio was 3 : 1. The aCGH analysis revealed a total of 2304 CNA, with an average of 69.8 ± 57.4 per case, of which 1197 were gains (52%), 926 were losses (40.2%), 105 were amplifications (4. 5%), and 76 were deletions (3.3%). A significant relationship was observed between the type of CNA and the degree of the tumor (chi-square test: χ 2 = 65,844; p < 0.0001; contingency coefficient: C = 0.1772; p < 0.0001). Evaluating the recurrent changes in at least 50% of the samples, we observe as the most frequent losses of the segments 22q13.1-q13.2 (82%), 1p35.3 (76%), and 14q13.1-q13.2 (67%), involving all histopathological grades. The analysis of these regions showed the inclusion of genes with functions such as regulation, maintenance of cell survival, reorganization of the cytoskeleton, cell signaling, and DNA repair, among others. However, overall, the profiles observed in meningiomas of this admixed population were very similar to the ones observed in Caucasian groups. An interesting finding was a recurrent gain of 8p22 observed only in grade I meningiomas, a region which includes DLC1, a suppressor candidate gene probably implicated in the developments or progression of meningiomas, usually found deleted, when related to CNAs.

Scalp Invasion by Atypical or Anaplastic Meningioma Is a Risk Factor for Development of Systemic Metastasis

BACKGROUND

Atypical and anaplastic meningiomas (AAMs) are rare and comprise approximately 5% of all meningiomas. Extracranial metastases in meningioma patients occur in 0.1% of all cases, but these lesions are difficult to treat and may be a poor prognostic factor.

METHODS

We conducted a retrospective chart review between 1990 and 2016 of patients who had surgical resection of AAM. In a cohort of 149 patients, 6 had metastatic lesions that were histologically confirmed to be meningioma. We compared baseline characteristics between patients with and without metastasis and performed a multivariate Cox regression analysis to assess risk factors for the development of systemic metastasis.

RESULTS

Six patients had histologically confirmed meningioma metastasis. We hypothesized that the presence of scalp invasion in patients could be a potential risk factor for the development of systemic meningioma metastasis. Nine out of the 149 patients without metastasis had scalp invasion, whereas 4 out of the 6 patients with metastasis had scalp invasion. Patients with metastasis had a median age of 62 ± 20. Patients without metastasis had a median age of 59 ± 15 years. Gender distribution was similar; approximately 50% of patients in each group were female. Eighty-five percent of patients with metastatic disease were white, and 65% of patients without metastatic disease were white. Among patients without metastatic disease, 77% had World Health Organization II tumors, whereas 50% of patients with metastatic disease had World Health Organization II tumors. In multivariate analysis including age, tumor grade, size, location, extent of resection, sex, and scalp invasion, the only significant predictor of systemic metastasis was scalp invasion (odds ratio = 39.67; 95% confidence interval = 3.74-421.12; P = 0.0023). Median overall survival (OS) with metastasis was 126 months, and median OS without metastasis was 158 months. Having metastatic disease was not significantly associated with worse OS (P = 0.33).

CONCLUSIONS

Metastasis development from AAM is a rare but serious event. Because scalp invasion is a strongly associated predictive factor for development of systemic metastasis in patients with AAM, it is necessary to consider strategies to prevent and to be vigilant of the development of scalp invasion.

Total DNA methylation as a biomarker of DNA damage and tumor malignancy in intracranial meningiomas

Background

Meningiomas are the most common primary intracranial tumors in adults. They are initially detected with neuroimaging techniques, but definite histological diagnosis requires tumor surgery to collect tumor tissue. Gross total resection is an optimal and final treatment for the majority of patients, followed by radiotherapy in malignant or refractory cases. However, there are a lot of uncertainties about i.a. the need for intervention in incidental cases, estimation of growth kinetics, risk of malignant transformation, or response to radiotherapy. Therefore a new diagnostic approach is needed. It has already been shown that epigenetics plays a crucial role in cancer biology, development, and progression. DNA methylation, the presence of 5-methylcytosine in DNA, is one of the main elements of a broad epigenetic program in a eukaryotic cell, with superior regulatory significance. Therefore, we decided to look at meningioma through changes of 5-methylcytosine.

Methods

We performed an analysis of the total amount of 5-methylcytosine in DNA isolated from intracranial meningioma tissues and peripheral blood samples of the same patients. The separation and identification of radioactively labeled nucleotides were performed using thin-layer chromatography.

Results

We found that the 5-methylcytosine level in DNA from intracranial meningiomas is inversely proportional to the malignancy grade. The higher the tumor WHO grade is, the lower the total DNA methylation. The amount of 5-methylcytosine in tumor tissue and peripheral blood is almost identical.

Conclusions

We conclude that the total DNA methylation can be a useful marker for brain meningioma detection, differentiation, and monitoring. It correlates with tumor WHO grade, and the 5-methylcytosine level in peripheral blood reflects that in tumor tissue. Therefore it’s applicable for liquid biopsy.

Our study creates a scope for further research on epigenetic mechanisms in neurooncology and can lead to the development of new diagnostic methods in clinical practice.

The Loss of 1p as a Reliable Marker of Progression in a Child with Aggressive Meningioma: A 16-Year Follow-Up Case Report

BACKGROUND

Here, we present the case of a 32-year-old female with a progressing history of meningioma for 16 years starting with an ethmoidal lesion in 2002. The initial tumor specimen of this patient showed a deletion of the short arm of chromosome 1 through a translocation between chromosomes 1 and 11 (t[1; 11]) as well as additional chromosomal aberrations, including partial or complete monosomy of chromosomes 2, 6, 7, 11, 13, and 22. These molecular characteristics were already known to be associated with an aggressive course of the disease, and the patient was, therefore, included in a strict follow-up regime. From 2003 to 2019, the patient suffered multiple relapses and consecutive tumor resections.

METHODS

Tumor specimen from 2017 was examined using a genome-wide methylation analysis as well as a whole-genome sequencing.

RESULTS

These analyses confirmed the findings of 2002 and proved genetic alteration in the meningioma to be very stable over the time. Yet SMO and AKT1 mutations, which have been described to be paradigmatic in frontobasal meningioma, could not be found.

CONCLUSIONS

Genetic characteristics seem to be very stable during progression of the disease. The loss of 1p represents to be a potential marker for the poor clinical course of our child meningioma. In 2019, our patient passed away due to the progress of her meningioma disease.

Deletions in the 17q chromosomal region and their influence on the clonal cytogenetic evolution of recurrent meningiomas

Objective

Meningiomas are among the most frequent intracranial tumors. Although the majority of meningiomas can be cured by surgical resection, up to 20% of the patients develop an aggressive clinical course with tumor recurrence or progressive disease.

Cytogenetically, meningiomas frequently harbour a normal karyotype or monosomy of chromosome 22 as the sole anomaly. However, progression of meningiomas is associated with a non-random pattern of secondary losses of the chromosomes and chromosomal regions 1p, 6, 10, 14, 18, and 19. There is evidence, that loss of chromosome 17 might be involved in the clonal cytogenetic evolution of recurrent meningiomas. The aim of this study was to determine the role of deletions in the 17q chromosomal region in patients with recurrent meningiomas.

Results

The authors retrospectively reviewed all patients that underwent repeated surgery for recurrent meningiomas between 1999 and 2015 at the Department of Neurosurgery of the Saarland University Hospital. Patients were included in this study if tumor samples from two or more different meningiomas were available.

A total of 7 patients underwent repeated surgery for recurrent meningiomas (4 males, 3 females, mean age: 45.4 years at the date of surgery) between 1999 and 2015. Collectively, 22 biopsies were analyzed with FISH (fluorescence-in-situ-hybridization) for the chromosomal region 17q23.3. In 20/22 (90.1%) specimens, the tumor samples harboured a significant deletion in the chromosomal region 17q (range: 10 to 63% of the cells). In 3/3 (100%) cases, deletion in the 17q chromosomal region was detectable in the primary tumor. In the tumor evolution, there was no steady in- or decrease in the percentage of this deletion.

Conclusion

Deletion in the 17q chromosomal region was present in the patients’ primary tumors as well as in late recurrences. Overall, a significant deletion in the 17q chromosomal region was detected in 90.1% of the tumors. Thus, the authors assume that deletion in the 17q chromosomal region displays rather an early event in meningioma progression. Accordingly, deletion in the 17q chromosomal region might clinically serve as a potential early marker for malignancy and a higher risk for recurrence in meningiomas.

Fluorescence imaging of meningioma cells with somatostatin receptor ligands: an in vitro study

BACKGROUND

The use of five-aminolevulinic acid (5-ALA) in the staining of malignant glioma cells has significantly improved intraoperative radicality in the resection of gliomas in the last decade. Currently, there is no comparable selective fluorescent substance available for meningiomas. There is however a demand for intraoperative fluorescent identification of, e.g., invasive skull base meningiomas to help improve safe radical resection. Meningiomas show high expression of the somatostatin receptor type 2, offering the possibility of receptor-targeted imaging. The authors used a somatostatin receptor-labeled fluorescence dye in the identification of meningiomas in vitro. The aim of this study was to evaluate the possibility of selective identification of meningioma cells with fluorescent techniques.

METHODS

Twenty-four primary human meningioma cell cultures were analyzed. The tumor cells were incubated with FAM-TOC (5,6-Carboxyfluoresceine-Tyr3-Octreotide). As a negative control, four human dura tissues were cultured as well as a mixed cell culture in vitro and incubated with the same somatostatin receptor-labeled fluorescence substance. After incubation, fluorescence signal and intensity in all cell cultures were analyzed at three different time points using a fluorescence microscope with 488 nm epi-illumination.

RESULTS

Sixteen WHO I, six WHO II, two WHO III meningioma primary cell cultures, and four dura cell cultures were analyzed. Fluorescence was detected in all meningioma cell cultures (22 cell culture stained strongly, 2 cell cultures moderately) directly after incubation up until 4 h later. There were no differences in the quality and quantity of fluorescence signal between the various meningioma grades. The fluorescence signal persisted unchanged during the analyzed period. In the negative control, dura cell cultures remained unstained.

CONCLUSIONS

This study demonstrates the use of FAM-TOC in the selective fluorescent identification of meningioma cells in vitro. Further evaluation of the chemical kinetics of the applied somatostatin receptor ligand and fluorescence dye is warranted. As a next step, an experimental animal model is needed to evaluate these promising results in vivo.

Advances in meningioma genetics: novel therapeutic opportunities

Meningiomas currently are among the most frequent intracranial tumours. Although the majority of meningiomas can be cured by surgical resection, ∼20% of patients have an aggressive clinical course with tumour recurrence or progressive disease, resulting in substantial morbidity and increased mortality of affected patients. During the past 3 years, exciting new data have been published that provide insights into the molecular background of meningiomas and link sites of tumour development with characteristic histopathological and molecular features, opening a new road to novel and promising treatment options for aggressive meningiomas. A growing number of the newly discovered recurrent mutations have been linked to a particular clinicopathological phenotype. Moreover, the updated WHO classification of brain tumours published in 2016 has incorporated some of these molecular findings, setting the stage for the improvement of future therapeutic efforts through the integration of essential molecular findings. Finally, an additional potential classification of meningiomas based on methylation profiling has been launched, which provides clues in the assessment of individual risk of meningioma recurrence. All of these developments are creating new prospects for effective molecularly driven diagnosis and therapy of meningiomas.

Transcriptomic analysis of aggressive meningiomas identifies PTTG1 and LEPR as prognostic biomarkers independent of WHO grade

Meningiomas are frequent central nervous system tumors. Although most meningiomas are benign (WHO grade I) and curable by surgery, WHO grade II and III tumors remain therapeutically challenging due to frequent recurrence. Interestingly, relapse also occurs in some WHO grade I meningiomas. Hence, we investigated the transcriptional features defining aggressive (recurrent, malignantly progressing or WHO grade III) meningiomas in 144 cases. Meningiomas were categorized into non-recurrent (NR), recurrent (R), and tumors undergoing malignant progression (M) in addition to their WHO grade. Unsupervised transcriptomic analysis in 62 meningiomas revealed transcriptional profiles lining up according to WHO grade and clinical subgroup. Notably aggressive subgroups (R+M tumors and WHO grade III) shared a large set of differentially expressed genes (n=332; p<0.01, FC>1.25). In an independent multicenter validation set (n=82), differential expression of 10 genes between WHO grades was confirmed. Additionally, among WHO grade I tumors differential expression between NR and aggressive R+M tumors was affirmed for PTTG1, AURKB, ECT2, UBE2C and PRC1, while MN1 and LEPR discriminated between NR and R+M WHO grade II tumors. Univariate survival analysis revealed a significant association with progression-free survival for PTTG1, LEPR, MN1, ECT2, PRC1, COX10, UBE2C expression, while multivariate analysis identified a prediction for PTTG1 and LEPR mRNA expression independent of gender, WHO grade and extent of resection. Finally, stainings of PTTG1 and LEPR confirmed malignancy-associated protein expression changes. In conclusion, based on the so far largest study sample of WHO grade III and recurrent meningiomas we report a comprehensive transcriptional landscape and two prognostic markers.

The correlation of clinical and chromosomal alterations of benign meningiomas and their recurrences

Meningiomas (MGs) are the frequent benign intracranial tumors. Their complete removal does not always guarantee relapse-free survival. Recurrence-associated chromosomal anomalies in MGs haves been proposed as prognostic factors in addition to the World Health Organisation (WHO) grading, tumor size and resection rate. The aim of this study was to evaluate the frequency of deletions on chromosomes in sporadic MGs and to correlate them with the clinical findings and tumor behaviour. Along with survival, the tumor recurrence was the main endpoint. Chromosomal loss of heterozygosity (LOH) was studied. 46 benign MGs were subjected to the analysis, complete tumor resection was intended and no early mortalities were observed. Incomplete removal was related to parasagittal location and psammomatous hisptopathology (p<0.01). Chromosomal alterations were present in 82.6% of cases; LOH at 22q (67.4%) and 1p (34.8%) were the most frequent and associated with male sex (p=0.04). Molecular findings were not specific for any of the histopathologic grade. Tumor recurrence (14 of 46) correlated with tumor size (≥35mm), LOH at 1p, 14q, coexistence of LOH at 1p/14q, 10q/14q, 'complex karyotype' status (≥2 LOHs excluding 22q), patient age (younger <35), and Simpson grading of resection rate (≥3 of worse prognosis). The last 3 variables were independent significant prognostic factors in multivariate analysis and of the same importance in recurrence prediction (Receiver Operating Characteristic curves comparison p>0.05). Among the cases of recurrence, tumor progression was observed in 3 of 14. In 2 cases, LOH on 1p and/or coexistence of LOH 1p/14q correlated with anaplastic transformation.

Genetic/molecular alterations of meningiomas and the signaling pathways targeted

Meningiomas are usually considered to be benign central nervous system tumors; however, they show heterogenous clinical, histolopathological and cytogenetic features associated with a variable outcome. In recent years important advances have been achieved in the identification of the genetic/molecular alterations of meningiomas and the signaling pathways involved. Thus, monosomy 22, which is often associated with mutations of the NF2 gene, has emerged as the most frequent alteration of meningiomas; in addition, several other genes (e.g., AKT1, KLF4, TRAF7, SMO) and chromosomes have been found to be recurrently altered often in association with more complex karyotypes and involvement of multiple signaling pathways. Here we review the current knowledge about the most relevant genes involved and the signaling pathways targeted by such alterations. In addition, we summarize those proposals that have been made so far for classification and prognostic stratification of meningiomas based on their genetic/genomic features.

Molecular biological determinations of meningioma progression and recurrence

Meningiomas are tumors that arise from the coverings of the brain or spinal cord. 5% of the cases turn into malignant forms with aggressive clinical behavior and increased risk of tumor recurrence. One hundred and five patients with meningiomas were operated by open surgery. To investigate predictors of meningioma recurrence in total 124 samples of 105 patients were investigated by iFISH. Dual-probe hybridization was performed to access chromosomal alterations of chromosomes 1p-, 9p- and 22q. Additionally, methylation of TIMP3 and p16 was analyzed with MS-PCR. Of the 105 investigated tumors 59.1% (62/105) were WHO grade I, 33.3% (35/105) were WHO grade II and 7.7% (8/105) were anaplastic meningiomas (grade III), respectively. The histopathological data correlates with the recurrence rate of the investigated meningiomas. Hypermethylation of TIMP3 was detected in 13.3% of all meningiomas: 10.9% in WHO grade I meningiomas, 25.0% in grade II and 14.3% in grade III meningiomas, respectively. No correlation of TIMP3 hypermethylation with tumor recurrence or WHO grade (p = 0.2) was observed. Interestingly, deletion of 1p36 emerged as a significant predictor of shorter overall survival (log rank test, p<0.001), whereas TIMP3 promoter methylation had no significant effect on overall survival (log rank test, p = 0.799). The results of the current study support the finding that the deletion of chromosome 1p is an independent marker of meningioma recurrence and progression (p = 0.0097). Therefore the measurement of genetic aberrations in meningiomas allows in a combined histological approach a more precise assessment of the prognosis of meningiomas than histopathology alone.

Proposal for a new risk stratification classification for meningioma based on patient age, WHO tumor grade, size, localization, and karyotype

BACKGROUND

Tumor recurrence remains the major clinical complication of meningiomas, the majority of recurrences occurring among WHO grade I/benign tumors. In the present study, we propose a new scoring system for the prognostic stratification of meningioma patients based on analysis of a large series of meningiomas followed for a median of >5 years.

METHODS

Tumor cytogenetics were systematically investigated by interphase fluorescence in situ hybridization in 302 meningioma samples, and the proposed classification was further validated in an independent series of cases (n = 132) analyzed by high-density (500K) single-nucleotide polymorphism (SNP) arrays.

RESULTS

Overall, we found an adverse impact on patient relapse-free survival (RFS) for males, presence of brain edema, younger patients (<55 years), tumor size >50 mm, tumor localization at intraventricular and anterior cranial base areas, WHO grade II/III meningiomas, and complex karyotypes; the latter 5 variables showed an independent predictive value in multivariate analysis. Based on these parameters, a prognostic score was established for each individual case, and patients were stratified into 4 risk categories with significantly different (P < .001) outcomes. These included a good prognosis group, consisting of approximately 20% of cases, that showed a RFS of 100% ± 0% at 10 years and a very poor-prognosis group with a RFS rate of 0% ± 0% at 10 years. The prognostic impact of the scoring system proposed here was also retained when WHO grade I cases were considered separately (P < .001).

CONCLUSIONS

Based on this risk-stratification classification, different strategies may be adopted for follow-up, and eventually also for treatment, of meningioma patients at different risks for relapse.

Establishment of a molecular cytogenetic analysis for native tumor tissue of meningiomas-suitable for clinical application

Background

Meningiomas are mostly benign tumors which arise from the meninges. They are among the cytogenetically best-studied solid tumors, mostly displaying a normal karyotype or, as a typical primary aberration, monosomy of chromosome 22. Further secondary chromosomal aberrations, especially the deletion of chromosome 1p, are correlated with increasing biological aggressiveness up to malignancy. These data are derived from the cytogenetical characterization of 661 meningiomas, from which the genetic progression score (GPS) has been developed. Due to the high expenditure of time and the expert knowledge for the cytogenetical characterization, the aim of this work was to establish an equally reliable yet more rapid clinical diagnosis based on fluorescence in situ hybridization (FISH) on meningiomas. Thus a comparison between the native tumor tissue and the primary culture of the same tumor was done in order to determine the most efficient method for a molecular cytogenetic characterization. The diagnostic procedure has to deliver fast and robust results, since they must enable the attending physician to plan the appropriate follow-up regimens for the patients. All in all, preparations of native tumor tissue as well as preparations of cell culture of 22 meningiomas were tested with FISH for aberrations concerning the prognostically relevant chromosome regions 1p and 9p, and the chromosomes 10, 14, 18 and 22 in comparison with the particular karyotypes revealed by conventional karyotyping using G-banding.

Results

The FISH examinations between native and cultured cells showed an accordance of 93.4%. The comparison of FISH data and karyotyping presented accordance to the greatest possible extent concerning the chromosomes 14, 18 and 22, but to detect the progression associated losses of 1p and 9p FISH is the most sensitive method.

Conclusions

The raised data reveal that both methods can be used for a significant analysis of chromosome aberrations on meningiomas. As a result of that the complex primary culture could also be avoided. Therefore a clinical diagnosis based on FISH on meningiomas is at hand for the assignment of patients to a suitable follow-up regimen.

Delineation of commonly deleted chromosomal regions in meningiomas by high-density single nucleotide polymorphism genotyping arrays

Despite recent advances in the identification of the cytogenetic profiles of meningiomas, a significant group of tumors still show normal karyotypes or few chromosomal changes. The authors analyzed the cytogenetic profile of 50 meningiomas using fluorescence in situ hybridization and high-density (500 K) single nucleotide polymorphism (SNP) arrays. Our results confirm that del(22q) (52%) and del(1p) (16%) (common deleted regions: 22q11.21-22q13.3. and 1p31.2-p36.33) are the most frequent alterations. Additionally, recurrent monosomy 14 (8%), del(6q) (10%), del(7p) (10%), and del(19q) (4%) were observed, while copy number patterns consistent with recurrent chromosomal gains, gene amplification, and copy number neutral loss of heterozygosity (cnLOH) were either absent or rare. Based on their overall SNP profiles, meningiomas could be classified into: (i) diploid cases, (ii) meningiomas with a single chromosomal change [e.g., monosomy 22/del(22q)] and (iii) tumors with ≥2 altered chromosomes. In summary, our results confirm and extend on previous observations showing that the most recurrent chromosomal abnormalities in meningiomas correspond to chromosome losses localized in chromosomes 1, 22 and less frequently in chromosomes 6, 7, 14, and 19, while chromosomal gains and cnLOH are restricted to a small proportion of cases. Finally, a set of cancer-associated candidate genes associated with the TP53, MYC, CASP3, HDAC1, and TERT signaling pathways was identified, in cases with coexisting monosomy 14 and del(1p).

Construction of oncogenetic tree models reveals multiple pathways of oral cancer progression

Oral cancer develops and progresses by accumulation of genetic alterations. The interrelationship between these alterations and their sequence of occurrence in oral cancers has not been thoroughly understood. In the present study, we applied oncogenetic tree models to comparative genomic hybridization (CGH) data of 97 primary oral cancers to identify pathways of progression. CGH revealed the most frequent gains on chromosomes 8q (72.4%) and 9q (41.2%) and frequent losses on 3p (49.5%) and 8p (47.5%). Both mixture and distance-based tree models suggested multiple progression pathways and identified +8q as an early event. The mixture model suggested two independent pathways namely a major pathway with -8p and a less frequent pathway with +9q. The distance-based tree identified three progression pathways, one characterized by -8p, another by -3p and the third by alterations +11q and +7p. Differences were observed in cytogenetic pathways of node-positive and node-negative oral cancers. Node-positive cancers were characterized by more non-random aberrations (n = 11) and progressed via -8p or -3p. On the other hand, node-negative cancers involved fewer non-random alterations (n = 6) and progressed along -3p. In summary, the tree models for oral cancers provided novel information about the interactions between genetic alterations and predicted their probable order of occurrence.

[Meningiomas: multiparametric approach for risk stratification and grading]

The prognosis of the generally benign meningiomas is mainly an issue of the likelihood of recurrence, which increases with WHO grade (7-20% in WHO grade I, 29-40% in WHO grade II, and 50-78% in WHO grade III meningiomas). Among clinical parameters the most important prognostic factor is the completeness of neurosurgical tumor resection. Among histopathological prognostic parameters the mitotic activity is the most important one. As the cutoffs of the mitotic index (MI) are defined for each grade by the WHO classification of brain tumors and because the MI can be applied as the sole grading criterion, the reliable and reproducible assessment of the MI is crucial for an appropriate risk stratification. This is provided by immunohistochemical mitosis markers, i.e., phospho-histone H3 (PHH3). The PHH3 method is superior to the conventional mitosis counting method and therefore allows a more reliable risk stratification. The Ki-67 labeling index provides additional prognostic information, especially in prognostically ambiguous meningiomas. Cytogenetically, the deletion of the short arm of one chromosome 1 (1p-) is an unfavorable prognostic parameter and is correlated with a high risk of recurrence. The enzyme reaction for alkaline phosphatase (ALPL) is a fast and efficient screening method, which strongly indicates an intact chromosome 1 in cases with a positive enzyme reaction.

Rtreemix: an R package for estimating evolutionary pathways and genetic progression scores

Summary: In genetics, many evolutionary pathways can be modeled by the ordered accumulation of permanent changes. Mixture models of mutagenetic trees have been used to describe disease progression in cancer and in HIV. In cancer, progression is modeled by the accumulation of chromosomal gains and losses in tumor cells; in HIV, the accumulation of drug resistance-associated mutations in the viral genome is known to be associated with disease progression. From such evolutionary models, genetic progression scores can be derived that assign measures for the disease state to single patients. Rtreemix is an R package for estimating mixture models of evolutionary pathways from observed cross-sectional data and for estimating associated genetic progression scores. The package also provides extended functionality for estimating confidence intervals for estimated model parameters and for evaluating the stability of the estimated evolutionary mixture models.

Availability:Rtreemix is an R package that is freely available from the Bioconductor project at http://www.bioconductor.org and runs on Linux and Windows.

Contact:jasmina@mpi-inf.mpg.de

Gene expression profiles of meningiomas are associated with tumor cytogenetics and patient outcome

Cytogenetic analysis is a powerful tool for predicting recurrence in meningiomas, even among histologically benign/grade I tumors. Despite this, no study has been reported in which the impact of tumor cytogenetics on the gene expression profiles (GEP) has been analyzed in meningiomas. Here, we analyzed the GEP of 47 tumors and correlated them with the most clinical relevant cytogenetic subgroups of meningiomas, as confirmed through the analysis of 172 patients. Additionally three normal meningeal samples were also studied. Overall, our results show a clear association between the clinically relevant cytogenetic subgroups of meningiomas including diploid tumors (n = 18), isolated -22/22q- (n = 12), del(1p36) alone (n = 4) and complex karyotypes associated with del(1p36) and/or -14q (n = 13) and their GEP. Accordingly, based on the expression of 85 genes (40 of which were coded in the altered chromosomes used for patient stratification) the cytogenetic class of the tumor could be predicted with an error of <1%, a clear association being found between the GEP and patient outcome (P = 0.03) but not tumor histopathology. In summary, we show a clear association between GEP of neoplastic cells and clinically relevant cytogenetic subgroups of meningiomas.

Correspondence of tumor localization with tumor recurrence and cytogenetic progression in meningiomas

OBJECTIVE

Meningiomas are mostly benign tumors that originate from the coverings of the brain and spinal cord. Cytogenetically, they reveal a normal karyotype or, typically, monosomy of chromosome 22. Progression of meningiomas is associated with a non-random pattern of secondary losses of other autosomes. Deletion of the short arm of one chromosome 1 is a decisive step to anaplastic growth in meningiomas.

METHODS

Statistical analyses were performed for the karyotypes of 661 meningiomas with respect to localization, progression, and recurrence of the tumor. A mathematical mixture model estimates typical pathogenetic routes in terms of the accumulation of somatic chromosome changes in tumor cells. The model generates a genetic progression score (GPS) that estimates the prognosis as related to the cytogenetic properties of a given tumor.

RESULTS

In 53 patients, one or several recurrences were documented over the period of observation. This corresponds to a total rate of recurrence of 8.0% after macroscopically complete tumor extirpation. Higher GPS values were shown to be strongly correlated with tumor recurrence (P = 2.9 x 10(-7)). High-risk tumors, both in terms of histology and cytogenetics, are localized much more frequently at the brain surface than at the cranial base (P = 1.2 x 10(-5) for World Health Organization grade and P = 3.3 x 10(-12) for GPS categorization).

CONCLUSION

The tendency of cranial base meningiomas to recur seems to depend on surgical rather than biological reasons. As a quantitative measure, the GPS allows for a more precise assessment of the prognosis of meningiomas than the established categorical cytogenetic markers.