Molecular classification and grading of meningioma

Mifepristone achieves tumor suppression and ferroptosis through PR/p53/HO1/GPX4 axis in meningioma cells

PURPOSE

This study explores the effects of mifepristone on the proliferation, motility, and invasion of malignant and benign meningioma cells, aiming to identify mifepristone-sensitive types and investigate the underlying molecular mechanisms.

METHODS

IOMM-Lee and HBL-52 meningioma cells were treated with 0, vehicle control (VC), 5, 10, 20, 40, and 80 μM of mifepristone for 12, 24, 48, 72, and 96 h. Proliferation was assessed via CCK8 assay, while motility and invasion were measured using wound scratch and transwell assays. RNA sequencing and RT-PCR were used to analyze gene expression changes.

RESULTS

Mifepristone inhibited proliferation, motility, and invasion in both IOMM-Lee and HBL-52 cells in a dose- and time-dependent manner. RNA sequencing showed up-regulated genes significantly enriched in the ferroptosis pathway in both cell lines, confirmed by increased p53 and HO1 expression, decreased GPX4 expression, lipid peroxidation, Fe2+ accumulation, and ROS release. Immunofluorescence staining and RT-PCR also revealed a corresponding decrease in mifepristone-related progesterone receptor expression.

CONCLUSION

Mifepristone induces ferroptosis in meningioma cells via the PR/p53/HO1/GPX4 axis, suggesting its potential as a treatment for ferroptosis-sensitive meningiomas. It also supplies new clues regarding ferroptosis as a treatment entry point for meningiomas.

Radiation Therapy for Meningiomas - Where Do We Stand and What's on the Horizon?

Radiation therapy, including conventionally fractionated external beam radiation therapy, stereotactic radiosurgery, and fractionated stereotactic radiation therapy, is a cornerstone in the interdisciplinary management of meningiomas. Recent advances in radiation oncology and also in other fields, such as neuropathology and imaging, have various implications for meningioma radiation therapy. This review aims to summarize current and anticipated developments, as well as active clinical trials related to the use of radiation therapy for meningiomas. In imaging, positron emission tomography has proven valuable for assessing the spatial extension of meningiomas and may enhance target delineation, treatment response monitoring, and recurrence assessment after radiation therapy. Particle therapy, including protons and carbon ions, as well as stereotactic radiosurgery and fractionated stereotactic radiation therapy, allow for conformal treatments that permit dose escalation in selected patients with high-grade meningiomas. Additionally, emerging integrated molecular and genetic classifications offer superior risk stratification and may refine patient selection for radiation therapy. However, there is a paucity of active meningioma trials directly investigating or refining the use of radiation therapy. In summary, significant advances in functional imaging, molecular and genetic diagnostics, and radiation treatment techniques hold the potential to improve patient outcomes and to avoid over- and undertreatment. Collaborative efforts and further clinical trials are essential to optimize meningioma radiation therapy.

Malignant Meningiomas: From Diagnostics to Treatment

Meningiomas account for approximately 40% of all primary brain tumors, of which 1.5% are classified as grade 3. Whilst meningiomas are discovered on imaging with high-grade meningiomas being associated with certain imaging features, the final diagnosis is based on histopathology in combination with molecular markers. According to the latest World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS), grade 3 should be assigned based on criteria for anaplastic meningiomas, which comprise malignant cytomorphology (anaplasia) that resembles carcinoma, high-grade sarcoma or melanoma; elevated mitotic activity; a TERT promoter mutation and/or a homozygous CDKN2A and/or CDKN2B deletion. Surgery remains the mainstay treatment modality for grade 3 meningiomas, followed by radiotherapy. Limited data are available on the effect of stereotactic radiosurgery and systemic therapy for grade 3 meningiomas; however, studies are underway. Despite optimal treatment, the estimated recurrence rate ranges between 50% and 95% with a 5-year survival rate of 66% and a 10-year estimated survival rate of 14% to 24%.

Current trends in the allocation of National Institute of Health funding of brain tumor research

Background

The National Institute of Health (NIH) provides a sizable annual budget toward brain tumor research. However, funding allocation for specific pathologies remains poorly described. We aimed to characterize the current landscape of NIH funding toward brain tumors as a function of pathology.

Methods

NIHRePORTER was queried to identify studies focused on glioblastoma, pediatric glioma, oligodendroglioma, brain metastasis, meningioma, pituitary adenoma, and vestibular schwannoma, from 2000 to 2023. Studies with R, U, and P funding mechanisms were included. Data were compiled and assessed according to pathology.

Results

Across these 7 tumors, 3320 unique studies with R, U, or P funding mechanisms were identified from 2000 to 2023. These were conducted across 480 unique institutions. The sum of funds allocated to all studies was $1 607 662 631. Glioblastoma commanded the largest portion of funds, representing 54% of R mechanisms, 55% of R01-funded studies, 48% of U mechanisms, and 49% of P mechanisms, and accounted for 51% ($813 556 423) of total funding. Brain metastasis was the second most-funded tumor, representing 31% of all R mechanisms, 31% of all R01-funded studies, 26% of all U mechanisms, and 28% of all P mechanisms, and accounted for 29% ($472 715 745) of funding. The remaining 14% of R mechanisms, 26% of U mechanisms, and 23% of P mechanisms focused on the remaining pathologies, and accounted for 20% ($321 390 463) of funding.

Conclusions

The current landscape of NIH funding for brain tumor research indicates that awarded mechanisms prioritize malignant intra-axial malignancies. Despite their prevalence, skull base neoplasia is far less represented in NIH-funded studies.

Surgery alone versus surgery plus adjuvant radiotherapy for WHO grade 2 meningioma: meta-analysis of reconstructed time-to-event data

INTRODUCTION

WHO Grade 2 meningiomas present diagnostic and management challenges. Surgery, particularly gross total resection (GTR), is crucial, often followed by adjuvant radiotherapy (RT); however, there are clinical equipoise and ongoing randomized trials of RT after GTR.

METHODS

This systematic review evaluates the efficacy of gross total resection (GTR) and GTR plus adjuvant radiotherapy (RT) for WHO grade 2 meningiomas, adhering to PRISMA guidelines. It excludes irrelevant studies, conducts a thorough search until January 2024, and specifically analyzes overall survival (OS) and progression-free survival (PFS) outcomes for WHO grade 2 meningiomas. Statistical analysis adopts a two-stage approach with the R package "IPDfromKM," and quality assessment is conducted using the ROBINS-I tool.

RESULTS

In our analysis of 23 studies involving 3822 WHO grade 2 meningioma patients, GTR + RT resulted in a significantly longer PFS (HR: 0.849, 95% CI: 0.730 to 0.988, p = 0.035) compared to GTR alone. Although OS trended better with GTR + RT (HR: 0.79, 95% CI: 0.57 to 1.11, p = 0.173), the difference was not statistically significant, suggesting the need for further investigation.

CONCLUSION

Our study reveals a benefit to adjuvant RT for improving PFS for WHO grade 2 meningiomas. Integrating molecular characteristics into treatment strategies will refine the management of these tumors in the future.

Malignant Transformation of Meningioma With TERT Promoter Mutation: A Case Report

High-grade meningiomas make up a relatively minor proportion of meningiomas, which are one of the most common types of primary intracranial tumors in adults. Though rare, a considerable portion of high-grade meningiomas arise from malignant transformation of benign meningiomas. The 2021 World Health Organization (WHO) classification criteria introduced molecular markers in the diagnosis and grading of central nervous system (CNS) tumors and assigned certain genomic mutations to grade 3 meningiomas. We report a case of a 54-year-old male patient who underwent stepwise malignant transformation of meningioma from WHO grade 1 to grade 3 within 10 years, during the course of five surgeries followed by adjuvant stereotactic radiosurgery and radiotherapy. We performed next-generation sequencing (NGS) on the most recent grade 3 meningioma specimen and found that it carried a telomerase reverse transcriptase promoter (TERTp) mutation (c.-124C>T) in accordance with the 2021 WHO criteria for grade 3 meningiomas. We then retrospectively examined the previous grade 1 and 2 specimens and found them to have the same mutation. We reviewed the significance of molecular markers in the diagnosis of meningiomas, possible genetic alterations associated with their malignant transformation, and what measures could be taken to effectively manage meningiomas considering NGS findings.

Topographic Patterns of Intracranial Meningioma Recurrences-Systematic Review with Clinical Implication

BACKGROUND

While several risk factors for recurrences have been defined, the topographic pattern of meningioma recurrences after surgical resection has been scarcely investigated. The possibility of theoretically predicting the site of recurrence not only allows us to better understand the pathogenetic bases of the disease and consequently to drive the development of new targeted therapies, but also guides the decision-making process for treatment strategies and tailored follow-ups to decrease/prevent recurrence.

METHODS

The authors performed a comprehensive and detailed systematic literature review of the EMBASE and MEDLINE electronic online databases regarding the topographic pattern of recurrence after surgical treatment for intracranial meningiomas. Demographics and histopathological, neuroradiological and treatment data, pertinent to the topography of recurrences, as well as time to recurrences, were extracted and analyzed.

RESULTS

Four studies, including 164 cases of recurrences according to the inclusion criteria, were identified. All studies consider the possibility of recurrence at the previous dural site; three out of four, which are the most recent, consider 1 cm outside the previous dural margin to be the main limit to distinguish recurrences closer to the previous site from those more distant. Recurrences mainly occur within or close to the surgical bed; higher values of proliferation index are associated with recurrences close to the original site rather than within it.

CONCLUSIONS

Further studies, including genomic characterization of different patterns of recurrence, will better clarify the main features affecting the topography of recurrences. A comparison between topographic classifications of intracranial meningioma recurrences after surgery and after radiation treatment could provide further interesting information.

Clinical implications of DNA methylation-based integrated classification of histologically defined grade 2 meningiomas

The combination of DNA methylation analysis with histopathological and genetic features allows for a more accurate risk stratification and classification of meningiomas. Nevertheless, the implications of this classification for patients with grade 2 meningiomas, a particularly heterogeneous tumor entity, are only partially understood. We correlate the outcomes of histopathologically confirmed grade 2 meningioma with an integrated molecular-morphologic risk stratification and determine its clinical implications. Grade 2 meningioma patients treated at our institution were re-classified using an integrated risk stratification involving DNA methylation array-based data, copy number assessment and TERT promoter mutation analyses. Grade 2 meningioma cases according to the WHO 2021 criteria treated between 2007 and 2021 (n = 100) were retrospectively analyzed. The median clinical and radiographic follow-up periods were 59.8 and 54.4 months. A total of 38 recurrences and 17 deaths were observed. The local control rates of the entire cohort after 2-, 4-, and 6-years were 84.3%, 68.5%, and 50.8%, with a median local control time of 77.2 months. The distribution of the integrated risk groups were as follows: 31 low, 54 intermediate, and 15 high risk cases. In the multivariable Cox regression analysis, integrated risk groups were significantly associated with the risk of local recurrence (hazard ratio (HR) intermediate: 9.91, HR high-risk: 7.29, p < 0.01). Gross total resections decreased the risk of local tumor progression (HR gross total resection: 0.19, p < 0.01). The comparison of 1p status and integrated risk groups (low vs. intermediate/high) revealed nearly identical local control rates within their respective subgroups. In summary, only around 50% of WHO 2021 grade 2 meningiomas have an intermediate risk profile. Integrated molecular risk stratification is crucial to guide the management of patients with grade 2 tumors and should be routinely applied to avoid over- and undertreatment, especially concerning the use of adjuvant radiotherapy.

Chronic hyperglycemia and intracranial meningiomas

Meningiomas are among the most common primary tumors of the central nervous system. Previous research into the meningioma histological appearance, genetic markers, transcriptome and epigenetic landscape has revealed that benign meningiomas significantly differ in their glucose metabolism compared to aggressive lesions. However, a correlation between the systemic glucose metabolism and the metabolism of the tumor hasn't yet been found. We hypothesized that chronic levels of glycaemia (approximated with glycated hemoglobin (HbA1c)) are different in patients with aggressive and benign meningiomas. The study encompassed 71 patients with de novo intracranial meningiomas, operated on in three European hospitals, two in Croatia and one in Spain. Our results show that patients with WHO grade 2 meningiomas had significantly higher HbA1c values compared to patients with grade 1 lesions (P = 0.0290). We also found a significant number of patients (19/71; 26.7%) being hyperglycemic, harboring all the risks that such a condition entails. Finally, we found a significant correlation between our patients' age and their preoperative HbA1c levels (P = 0.0008, ρ(rho) = 0.388), suggesting that older meningioma patients are at a higher risk of having their glycaemia severely dysregulated. These findings are especially important considering the current routine and wide-spread use of corticosteroids as anti-edematous treatment. Further research in this area could lead to better understanding of meningiomas and have immediate clinical impact.

Susceptibility-Weighted MRI for Predicting NF-2 Mutations and S100 Protein Expression in Meningiomas

S100 protein expression levels and neurofibromatosis type 2 (NF-2) mutations result in different disease courses in meningiomas. This study aimed to investigate non-invasive biomarkers of NF-2 copy number loss and S100 protein expression in meningiomas using morphological, radiomics, and deep learning-based features of susceptibility-weighted MRI (SWI). This retrospective study included 99 patients with S100 protein expression data and 92 patients with NF-2 copy number loss information. Preoperative cranial MRI was conducted using a 3T clinical MR scanner. Tumor volumes were segmented on fluid-attenuated inversion recovery (FLAIR) and subsequent registration of FLAIR to high-resolution SWI was performed. First-order textural features of SWI were extracted and assessed using Pyradiomics. Morphological features, including the tumor growth pattern, peritumoral edema, sinus invasion, hyperostosis, bone destruction, and intratumoral calcification, were semi-quantitatively assessed. Mann-Whitney U tests were utilized to assess the differences in the SWI features of meningiomas with and without S100 protein expression or NF-2 copy number loss. A logistic regression analysis was used to examine the relationship between these features and the respective subgroups. Additionally, a convolutional neural network (CNN) was used to extract hierarchical features of SWI, which were subsequently employed in a light gradient boosting machine classifier to predict the NF-2 copy number loss and S100 protein expression. NF-2 copy number loss was associated with a higher risk of developing high-grade tumors. Additionally, elevated signal intensity and a decrease in entropy within the tumoral region on SWI were observed in meningiomas with S100 protein expression. On the other hand, NF-2 copy number loss was associated with lower SWI signal intensity, a growth pattern described as "en plaque", and the presence of calcification within the tumor. The logistic regression model achieved an accuracy of 0.59 for predicting NF-2 copy number loss and an accuracy of 0.70 for identifying S100 protein expression. Deep learning features demonstrated a strong predictive capability for S100 protein expression (AUC = 0.85 ± 0.06) and had reasonable success in identifying NF-2 copy number loss (AUC = 0.74 ± 0.05). In conclusion, SWI showed promise in identifying NF-2 copy number loss and S100 protein expression by revealing neovascularization and microcalcification characteristics in meningiomas.