Atypical and anaplastic meningiomas treated with bevacizumab

Peptide radionuclide radiation therapy with Lutathera in multirecurrent nonanaplastic meningiomas: antitumoral activity study by growth rate analysis

PURPOSE

Several retrospective studies and meta-analyses of Peptide Radionuclide Radiation Therapy in meningiomas suggest six-month progression-free survival improvement for WHO grade 1 and 2 meningiomas. In the present study, we aimed to evaluate the impact of such treatment on three-dimensional volume growth rate (3DVGR) in nonanaplastic meningiomas.

METHODS

The authors performed a retrospective study including eight patients treated with Lutathera®. Millimetric 3D T1-weighted with gadolinium enhancement magnetic resonance imaging sequences were requested for volume measurement. Then, tumor growth rate was classified following a previously described 3DVGR classification (Graillon et al.).

RESULTS

Patients harbored seven WHO grade 2 meningiomas and one aggressive WHO grade 1. All patients, except one, underwent four treatment cycles. 3DVGR significantly decreased at 3, 6, and 12 months after treatment initiation analyzing each lesion separately. Mean and median 3DVGR from all patients were respectively at 29.5% and 44.5%/6 months before treatment initiation, then at 16.5% and 25%/6 months at three months post-treatment initiation, 9.5% and 4.5%/6 months after 6 months, as well as 9.5% and 10.5%/6 months after 12 months. At 3, 6, and 12 months after treatment initiation, 4/8, 6/7, and 5/6 patients were class 2 (stabilization or severe 3DVGR slowdown), respectively. No patient was class 1 at 6 and 12 months, suggesting a lack of drug response.

CONCLUSION

In nonanaplastic meningiomas, Lutathera®'s antitumoral activity appeared delayed and more likely observed at six months, while no major response was observed under treatment. Moreover, its antitumoral activity persisted for 12-18 months following treatment initiation.

Efficacy and toxicity of bimodal radiotherapy in WHO grade 2 meningiomas following subtotal resection with carbon ion boost: Prospective phase 2 MARCIE trial

BACKGROUND

Novel radiotherapeutic modalities using carbon ions provide an increased relative biological effectiveness (RBE) compared to photons, delivering a higher biological dose while reducing radiation exposure for adjacent organs. This prospective phase 2 trial investigated bimodal radiotherapy using photons with carbon-ion (C12)-boost in patients with WHO grade 2 meningiomas following subtotal resection (Simpson grade 4 or 5).

METHODS

A total of 33 patients were enrolled from July 2012 until July 2020. The study treatment comprised a C12-boost (18 Gy [RBE] in 6 fractions) applied to the macroscopic tumor in combination with photon radiotherapy (50 Gy in 25 fractions). The primary endpoint was the 3-year progression-free survival (PFS), and the secondary endpoints included overall survival, safety and treatment toxicities.

RESULTS

With a median follow-up of 42 months, the 3-year estimates of PFS, local PFS and overall survival were 80.3%, 86.7%, and 89.8%, respectively. Radiation-induced contrast enhancement (RICE) was encountered in 45%, particularly in patients with periventricularly located meningiomas. Patients exhibiting RICE were mostly either asymptomatic (40%) or presented immediate neurological and radiological improvement (47%) after the administration of corticosteroids or bevacizumab in case of radiation necrosis (3/33). Treatment-associated complications occurred in 1 patient with radiation necrosis who died due to postoperative complications after resection of radiation necrosis. The study was prematurely terminated after recruiting 33 of the planned 40 patients.

CONCLUSIONS

Our study demonstrates a bimodal approach utilizing photons with C12-boost may achieve a superior local PFS to conventional photon RT, but must be balanced against the potential risks of toxicities.

Particle beam radiotherapy in the treatment of WHO grade 2 and 3 meningiomas: an early experience from Shanghai Proton and Heavy Ion Center

PURPOSE

To investigate the efficacy and safety of particle beam radiotherapy (PBRT) in the management of patients with WHO grade 2 and 3 meningiomas.

METHODS

Thirty-six consecutive and non-selected patients with WHO grade 2 (n = 28) and grade 3 (n = 8) meningiomas were treated at the Shanghai Proton and Heavy Ion Center, from May 2015 to March 2022. The median age of the cohort at PBRT was 48 years. There were 25 and 11 patients treated with PBRT in the setting of newly diagnosed diseases and progressive/recurrent diseases, respectively. PBRT was utilized as re-irradiation in 5 patients. Proton radiotherapy (PRT) and carbon-ion radiotherapy (CIRT), with a median dose of 60 Gy-Equivalent (GyE), were provided to 30 and 6 patients, respectively.

RESULTS

With a median follow-up of 23.3 months, the local control rates were 92.0%, 82.0%, and 82.0% at 1, 2, and 3 years for the entire cohort, respectively. Patients with WHO grade 2 meningiomas (100%, 94.1%, 94,1% at 1,2,3 years) had a much better local control than those with WHO grade 3 meningiomas (50%, 25%, 25% at 1,2,3 years; P < 0.001). Three patients, all with WHO grade 3 meningiomas, had deceased at the time of this analysis. Multivariate analyses revealed that WHO grade (grade 2 vs. 3) (p = 0.016) was a significant prognosticator for local control. No severe toxicities (G3 or above) were observed.

CONCLUSIONS

Treatment-induced efficacy and toxicities to PBRT in WHO grade 2 and 3 meningiomas were both highly acceptable. Longer follow-up is needed to evaluate the long-term outcome in terms of disease control, survival, as well as potential late effects.

Novel Advances in Treatment of Meningiomas: Prognostic and Therapeutic Implications

Meningiomas are the most frequent histotypes of tumors of the central nervous system. Their incidence is approximately 35% of all primary brain tumors. Although they have the status of benign lesions, meningiomas are often associated with a decreased quality of life due to focal neurological deficits that may be related. The optimal treatment is total resection. Histological grading is the most important prognostic factor. Recently, molecular alterations have been identified that are specifically related to particular phenotypes and, probably, are also responsible for grading, site, and prognostic trend. Meningiomas recur in 10-25% of cases. In these cases, and in patients with atypical or anaplastic meningiomas, the methods of approach are relatively insufficient. To date, data on the molecular biology, genetics, and epigenetics of meningiomas are insufficient. To achieve an optimal treatment strategy, it is necessary to identify the mechanisms that regulate tumor formation and progression. Combination therapies affecting multiple molecular targets are currently opening up and have significant promise as adjuvant therapeutic options. We review the most recent literature to identify studies investigating recent therapeutic treatments recently used for meningiomas.

Interdisciplinary Therapeutic Approaches to Atypical and Malignant Meningiomas

Meningiomas have the highest incidence among brain tumors. In contrast to benign tumors that constitute the majority of this tumor entity, the treatment of aggressive meningiomas (WHO Grade 2 and 3) is more challenging, requiring gross total removal of the tumor and the affected dura and adjuvant radiotherapy. Sometimes the location and/or the configuration of the tumor do not favor radical surgical resection without endangering the patient's clinical condition after surgery and pharmacological therapy has, until now, not been proven to be a reliable alternative. Discussion: In this narrative review, we discuss the current literature with respect to the management of meningiomas, discussing the importance of the grade of resection in the overall prognosis of the patient and in the planning of adjuvant therapy. Conclusions: According to the location and size of the tumor, radical resection should be taken into consideration. In patients with aggressive meningiomas, adjuvant radiotherapy should be performed after surgery. In cases of skull base meningiomas, a maximal, though safe, resection should take place before adjuvant therapy. An interdisciplinary approach is beneficial for patients with primary or recurrent meningioma.

The role of radiation therapy and systemic treatments in meningioma: The present and the future

Meningiomas are the most prevalent tumors of the central nervous system. Their standard treatment is surgery, which can be curative. Adjuvant radiotherapy treatment is reserved for newly diagnosed cases of grade II and grade III meningiomas in cases of recurrent disease or when surgery is not radical or feasible. However, around 20% of these patients cannot undergo further surgical and/or radiotherapy treatment. Systemic oncological therapy can find its place in this setting. Several tyrosine kinase inhibitors have been tested (gefitinib, erlotinib, sunitinib) with unsatisfactory or negative results. Bevacizumab has shown encouraging results in these settings of patients. Immunotherapy with immune checkpoint inhibitors has reported interesting results with modest objective response rates. Several ongoing studies are assessing different target therapies and multimodal therapies; the results are to be disclosed. Not only a better understanding of the molecular characteristics in meningiomas has allowed the gathering of more information regarding pathogenesis and prognosis, but in addition, the availability of new target therapy, immunotherapy, and biological drugs has widened the scope of potentially effective treatments in this patient population. The aim of this review was to explore the radiotherapy and systemic treatments of meningioma with an analysis of ongoing trials and future therapeutic perspectives.

Extracerebral anaplastic meningioma

Key Clinical Message

Conventional treatments of anaplastic meningioma include surgery and radiotherapy. Temozolomide is also an option. Metastases to extracerebral organs are very rare and hardly manageable. Antiangiogenic drugs could represent a salvage therapy.

Abstract

Anaplastic meningioma is an unusual tumor subtype that rarely involves organs outside the brain. In our case, a patient with cerebral meningioma developed lung metastases after 19 years from the initial tumor appearance. This unpredictable behavior could make complex the diagnosis.

Medical Management of Meningiomas

Meningiomas represent the most common type of benign tumor of the extra-axial compartment. Although most meningiomas are benign World Health Organization (WHO) grade 1 lesions, the increasingly prevalent of WHO grade 2 lesion and occasional grade 3 lesions show worsened recurrence rates and morbidity. Multiple medical treatments have been evaluated but show limited efficacy. We review the status of medical management in meningiomas, highlighting successes and failures of various treatment options. We also explore newer studies evaluating the use of immunotherapy in management.

Advances in the systemic therapy for recurrent meningiomas and the challenges ahead

INTRODUCTION

Meningiomas represent the most common primary neoplasms of the central nervous system (CNS). 20% present with atypical (WHO grade II) or malignant (grade III) meningiomas, which show aggressive biologic behavior and high recurrence. Although surgical resection and radiation therapy are the primary treatment options for these tumors, there is a subgroup of patients who do not respond well to or are poor candidates for these approaches, leading to the exploration of systemic therapies as an alternative.

AREAS COVERED

The literature on different therapeutic groups of systemic drugs for recurrent meningiomas is reviewed, with a focus on the different molecular targets. Past and current ongoing clinical trials are also discussed.

EXPERT OPINION

To date, there is no recognized treatment that has demonstrated a substantial increase in progression-free or overall survival rates. Nonetheless, therapies targeting anti-VEGF have exhibited more encouraging results in general. The examination of genomic and epigenomic traits of meningiomas, along with the integration of molecular markers into the latest WHO tumor grading system, has provided valuable insights. This has opened avenues for exploring numerous intracellular and extracellular pathways, as well as mutations, that have been targeted in ongoing clinical trials.

Innovative treatments for meningiomas

Multi-recurrent high-grade meningiomas remain an unmet medical need in neuro-oncology when iterative surgeries and radiation therapy sessions fail to control tumor growth. Nevertheless, the last 10years have been marked by multiple advances in the comprehension of meningioma tumorigenesis via the discovery of new driver mutations, the identification of activated intracellular signaling pathways, and DNA methylation analyses, providing multiple potential therapeutic targets. Today, Anti-VEGF and mTOR inhibitors are the most used and probably the most active drugs in aggressive meningiomas. Peptide radioactive radiation therapy aims to target SSTR2A receptors, which are strongly expressed in meningiomas, but have an insufficient effect in most aggressive meningiomas, requiring the development of new techniques to increase the dose applied to the tumor. Based on the multiple potential intracellular targets, multiple targeted therapy clinical trials targeting Pi3K-Akt-mTOR and MAP kinase pathways as well as cell cycle and particularly, cyclin D4-6 are ongoing. Recently discovered driver mutations, SMO, Akt, and PI3KCA, offer new targets but are mostly observed in benign meningiomas, limiting their clinical relevance mainly to rare aggressive skull base meningiomas. Therefore, NF2 mutation remains the most frequent mutation and main challenging target in high-grade meningioma. Recently, inhibitors of focal adhesion kinase (FAK), which is involved in tumor cell adhesion, were tested in a phase 2 clinical trial with interesting but insufficient activity. The Hippo pathway was demonstrated to interact with NF2/Merlin and could be a promising target in NF2-mutated meningiomas with ongoing multiple preclinical studies and a phase 1 clinical trial. Recent advances in immune landscape comprehension led to the proposal of the use of immunotherapy in meningiomas. Except in rare cases of MSH2/6 mutation or high tumor mass burden, the activity of PD-1 inhibitors remains limited; however, its combination with various radiation therapy modalities is particularly promising. On the whole, therapeutic management of high-grade meningiomas is still challenging even with multiple promising therapeutic targets and innovations.

Docetaxel targets aggressive methylation profiles and serves as a radiosensitizer in high-risk meningiomas

BACKGROUND

Meningioma is the most common primary intracranial tumor in adults. A subset of these tumors recur and invade the brain, even after surgery and radiation, resulting in significant disability. There is currently no standard-of-care chemotherapy for meningiomas. As genomic DNA methylation profiling can prognostically stratify these lesions, we sought to determine whether any existing chemotherapies might be effective against meningiomas with high-risk methylation profiles.

METHODS

A previously published dataset of meningioma methylation profiles was used to screen for clinically significant CpG methylation events and associated cellular pathways. Based on these results, patient-derived meningioma cell lines were used to test candidate drugs in vitro and in vivo, including efficacy in conjunction with radiotherapy.

RESULTS

We identified 981 genes for which methylation of mapped CpG sites was related to progression-free survival in meningiomas. Associated molecular pathways were cross-referenced with FDA-approved cancer drugs, which nominated Docetaxel as a promising candidate for further preclinical analyses. Docetaxel arrested growth in 17 meningioma cell sources, representing all tumor grades, with a clinically favorable IC50 values ranging from 0.3 nM to 10.7 mM. The inhibitory effects of this medication scaled with tumor doubling time, with maximal benefit in fast-growing lesions. The combination of Docetaxel and radiation therapy increased markers of apoptosis and double-stranded DNA breaks, and extended the survival of mice engrafted with meningioma cells relative to either modality alone.

CONCLUSIONS

Global patterns of DNA methylation may be informative for the selection of chemotherapies against meningiomas, and existing drugs may enhance radiation sensitivity in high-risk cases.

Glioblastoma and Other Primary Brain Malignancies in Adults: A Review

Importance

Malignant primary brain tumors cause more than 15 000 deaths per year in the United States. The annual incidence of primary malignant brain tumors is approximately 7 per 100 000 individuals and increases with age. Five-year survival is approximately 36%.

Observations

Approximately 49% of malignant brain tumors are glioblastomas, and 30% are diffusely infiltrating lower-grade gliomas. Other malignant brain tumors include primary central nervous system (CNS) lymphoma (7%) and malignant forms of ependymomas (3%) and meningiomas (2%). Symptoms of malignant brain tumors include headache (50%), seizures (20%-50%), neurocognitive impairment (30%-40%), and focal neurologic deficits (10%-40%). Magnetic resonance imaging before and after a gadolinium-based contrast agent is the preferred imaging modality for evaluating brain tumors. Diagnosis requires tumor biopsy with consideration of histopathological and molecular characteristics. Treatment varies by tumor type and often includes a combination of surgery, chemotherapy, and radiation. For patients with glioblastoma, the combination of temozolomide with radiotherapy improved survival when compared with radiotherapy alone (2-year survival, 27.2% vs 10.9%; 5-year survival, 9.8% vs 1.9%; hazard ratio [HR], 0.6 [95% CI, 0.5-0.7]; P < .001). In patients with anaplastic oligodendroglial tumors with 1p/19q codeletion, probable 20-year overall survival following radiotherapy without vs with the combination of procarbazine, lomustine, and vincristine was 13.6% vs 37.1% (80 patients; HR, 0.60 [95% CI, 0.35-1.03]; P = .06) in the EORTC 26951 trial and 14.9% vs 37% in the RTOG 9402 trial (125 patients; HR, 0.61 [95% CI, 0.40-0.94]; P = .02). Treatment of primary CNS lymphoma includes high-dose methotrexate-containing regimens, followed by consolidation therapy with myeloablative chemotherapy and autologous stem cell rescue, nonmyeloablative chemotherapy regimens, or whole brain radiation.

Conclusions and Relevance

The incidence of primary malignant brain tumors is approximately 7 per 100 000 individuals, and approximately 49% of primary malignant brain tumors are glioblastomas. Most patients die from progressive disease. First-line therapy for glioblastoma is surgery followed by radiation and the alkylating chemotherapeutic agent temozolomide.

Signaling pathways in brain tumors and therapeutic interventions

Brain tumors, although rare, contribute to distinct mortality and morbidity at all ages. Although there are few therapeutic options for brain tumors, enhanced biological understanding and unexampled innovations in targeted therapies and immunotherapies have considerably improved patients' prognoses. Nonetheless, the reduced response rates and unavoidable drug resistance of currently available treatment approaches have become a barrier to further improvement in brain tumor (glioma, meningioma, CNS germ cell tumors, and CNS lymphoma) treatment. Previous literature data revealed that several different signaling pathways are dysregulated in brain tumor. Importantly, a better understanding of targeting signaling pathways that influences malignant behavior of brain tumor cells might open the way for the development of novel targeted therapies. Thus, there is an urgent need for a more comprehensive understanding of the pathogenesis of these brain tumors, which might result in greater progress in therapeutic approaches. This paper began with a brief description of the epidemiology, incidence, risk factors, as well as survival of brain tumors. Next, the major signaling pathways underlying these brain tumors' pathogenesis and current progress in therapies, including clinical trials, targeted therapies, immunotherapies, and system therapies, have been systemically reviewed and discussed. Finally, future perspective and challenges of development of novel therapeutic strategies in brain tumor were emphasized.

Emerging systemic treatment options in meningioma

PURPOSE

Meningiomas are the most frequently diagnosed intracranial neoplasms. Usually, they are treated by surgical resection in curative intent. Radiotherapy and stereotactic radiosurgery are commonly applied in the adjuvant setting in newly diagnosed atypical (CNS WHO grade 2), and anaplastic (CNS WHO grade 3) meningioma, especially if gross total resection is not feasible, and in recurrent cases. Conversely, the evidence for pharmacotherapy in meningioma is scarce.

METHODS

The available literature of systemic treatment in meningioma was screened using PubMed, and ongoing clinical trials were explored using ClinicalTrials.gov.

RESULTS

Classical cytotoxic agents, somatostatin analogs, and antihormone treatments have shown only limited efficacy. In contrast, tyrosine kinase inhibitors and monoclonal antibodies, especially those targeting angiogenic signaling such as sunitinib and bevacizumab, have shown promising antitumoral activity in small phase 2 trials. Moreover, results of recent landmark studies on (epi-)genetic alterations in meningioma revealed potential therapeutic targets which are currently under investigation. These include inhibitors of mammalian target of rapamycin (mTOR), focal adhesion kinase (FAK), cyclin-dependent kinases (CDK), phosphoinositide-3-kinase (PI3K), sonic hedgehog signaling, and histone deacetylases. In addition, clinical trials evaluating immune checkpoint inhibitors such as ipilimumab, nivolumab, pembrolizumab and avelumab are currently being conducted and early results suggest clinically meaningful responses in a subset of patients.

CONCLUSIONS

There is a paucity of high-level evidence on systemic treatment options in meningioma. However, interesting novel treatment targets have been identified in the last decade. Positive signals of anti-angiogenic agents, genomically targeted agents and immunotherapy in early phase trials should be confirmed in large prospective controlled trials.

Current Knowledge on Spinal Meningiomas Epidemiology, Tumor Characteristics and Non-Surgical Treatment Options: A Systematic Review and Pooled Analysis (Part 1)

BACKGROUND

Spinal meningiomas are the most common primary intradural spinal tumors. Although they are a separate entity, a large portion of the knowledge on spinal meningiomas is based on findings in intracranial meningiomas. Therefore, a comprehensive review of all the literature on spinal meningiomas was performed.

METHODS

Electronic databases were searched for all studies on spinal meningiomas dating from 2000 and onward. Findings of matching studies were pooled to strengthen the current body of evidence.

RESULTS

A total of 104 studies were included. The majority of patients were female (72.83%), elderly (peak decade: seventh), and had a world health organization (WHO) grade 1 tumor (95.7%). Interestingly, the minority of pediatric patients had a male overrepresentation (62.0% vs. 27.17%) and higher-grade tumors (33.3% vs. 4.3%). Sensory and motor dysfunction and pain were the most common presenting symptoms. Despite a handful of studies reporting promising findings associated with the use of non-surgical treatment options, the literature still suffers from contradictory results and limitations of study designs.

CONCLUSIONS

Elderly females with WHO grade 1 tumors constituted the stereotypical type of patient. Compared to surgical alternatives, the evidence for the use of non-surgical treatments is still relatively weak.

Histone deacetylase inhibitors enhance oncolytic herpes simplex virus therapy for malignant meningioma

Approximately 20% of meningiomas are not benign (higher grade) and tend to relapse after surgery and radiation therapy. Malignant (anaplastic) meningioma (MM) is a minor subset of high-grade meningioma that is lethal with no effective treatment options currently. Oncolytic herpes simplex virus (oHSV) is a powerful anti-cancer modality that induces both direct cell death and anti-tumor immunity, and has shown activity in preclinical models of MM. However, clinically meaningful efficacy will likely entail rational mechanistic combination approaches. We here show that epigenome modulator histone deacetylase inhibitors (HDACi) increase anti-cancer effects of oHSV in human MM models, IOMM-Lee (NF2 wild-type) and CH157 (NF2 mutant). Minimally toxic, sub-micromolar concentrations of pan-HDACi, Trichostatin A and Panobinostat, substantively increased the infectability and spread of oHSV G47Δ within MM cells in vitro, resulting in enhanced oHSV-mediated killing of target cells when infected at low multiplicity of infection (MOI). Transcriptomics analysis identified selective alteration of mRNA processing and splicing modules that might underlie the potent anti-MM effects of combining HDACi and oHSV. In vivo, HDACi treatment increased intratumoral oHSV replication and boosted the capacity of oHSV to control the growth of human MM xenografts. Thus, our work supports further translational development of the combination approach employing HDACi and oHSV for the treatment of MM.

The role of bevacizumab for treatment-refractory intracranial meningiomas: a single institution's experience and a systematic review of the literature

INTRODUCTION

Meningiomas account for over 30% of all primary brain tumors. While surgery can be curative for these tumors, several factors may lead to a higher likelihood of recurrence. For recurrent meningiomas, bevacizumab may be considered as a therapeutic agent, but literature regarding its efficacy is sparse. Thus, we present a systematic review of the literature and case series of patients from our institution with treatment-refractory meningiomas who received bevacizumab.

METHODS

Patients at our institution who were diagnosed with recurrent meningioma between January 2000 and September 2020 and received bevacizumab monotherapy were included in this study. Bevacizumab duration and dosages were noted, as well as progression-free survival (PFS) after the first bevacizumab injection. A systematic review of the literature was also performed.

RESULTS

Twenty-three patients at our institution with a median age of 55 years at initial diagnosis qualified for this study. When bevacizumab was administered, 2 patients had WHO grade I meningiomas, 10 patients had WHO grade II meningiomas, and 11 patients had WHO grade III meningiomas. Median PFS after the first bevacizumab injection was 7 months. Progression-free survival rate at 6 months was 57%. Two patients stopped bevacizumab due to hypertension and aphasia. Systematic review of the literature showed limited ability for bevacizumab to control tumor growth.

CONCLUSION

Bevacizumab is administered to patients with treatment-refractory meningiomas and, though its effectiveness is limited, outperforms other systemic therapies reported in the literature. Further studies are required to identify a successful patient profile for utilization of bevacizumab.

Diagnostic and Therapeutic Strategy in Anaplastic (Malignant) Meningioma, CNS WHO Grade 3

Simple Summary

Only 1% of all meningioma diagnosis is classified as malignant (anaplastic) meningioma. Due to their rarity, clinical management of these tumors presents several gaps. In this review, we investigate current knowledge of anaplastic meningioma focusing on their pathological and radiological diagnosis, molecular assessment, and loco-regional and systemic management. Despite the current marginal role of systemic therapy, it is possible that the increasing knowledge of molecular altered pathways of the disease will lead to the development of novel effective systemic treatments.

Abstract

Background: Meningiomas are the most common primary central nervous system malignancies accounting for 36% of all intracranial tumors. However, only 1% of meningioma is classified as malignant (anaplastic) meningioma. Due to their rarity, clinical management of these tumors presents several gaps. Methods: We carried out a narrative review aimed to investigate current knowledge of anaplastic meningioma focusing on their pathological and radiological diagnosis, molecular assessment, and loco-regional and systemic management. Results: The most frequent genetic alteration occurring in meningioma is the inactivation in the neurofibromatosis 2 genes (merlin). The accumulation of copy number losses, including 1p, 6p/q, 10q, 14q, and 18p/q, and less frequently 2p/q, 3p, 4p/q, 7p, 8p/q, and 9p, compatible with instability, is restricted to NF2 mutated meningioma. Surgery and different RT approaches represent the milestone of grade 3 meningioma management, while there is a marginal role of systemic therapy. Conclusions: Anaplastic meningiomas are rare tumors, and diagnosis should be suspected and confirmed by trained radiologists and pathologists. Despite the current marginal role of systemic therapy, it is possible that the increasing knowledge of molecular altered pathways of the disease will lead to the development of novel effective systemic treatments.

Co-Targeting MAP Kinase and Pi3K-Akt-mTOR Pathways in Meningioma: Preclinical Study of Alpelisib and Trametinib

Simple Summary

Multi recurrent or high-grade meningiomas remain an unmet medical need in neuro-oncology. Several studies have highlighted the potential therapeutic efficacy of mTor inhibitors to control tumoral growth of meningiomas. However, a positive feedback on AKT oncogenic pathway from these drugs may explain the modest success. Our aim was to target Pi3kinase upstream mTor, and MAP kinase pathway, overactivated in meningiomas, alone or in combined targeting in comparison to mTor targeting. Our in vitro results obtained on three meningioma cell lines and on a large series of fresh human meningiomas, including 35 WHO grade 1, 23 grade 2, and five grade 3, showed that co-targeting Pi3kinase and MAP kinase seemed promising, opening new therapeutic strategies in these tumors.

Abstract

Recurrent or high-grade meningiomas are an unmet medical need. Recently, we demonstrated that targeting mTOR by everolimus was relevant both in vitro and in humans. However, everolimus induces an AKT activation that may impact the anti-proliferative effect of the drug. Moreover, the MAP kinase pathway was shown to be involved in meningioma tumorigenesis. We therefore targeted both the Pi3k-AKT-mTOR and MAP kinase pathways by using combinations of the Pi3k inhibitor alpelisib and the MEK inhibitor trametinib. Our study was performed in vitro on the human meningioma cell lines and on a large series of primary cultures providing from 63 freshly operated meningiomas including 35 WHO grade 1, 23 grade 2, and five grade 3, half of which presented a NF2 genomic alteration. Alpelisib induced a higher inhibitory effect on cell viability and proliferation than everolimus in all cell lines and 32 randomly selected tumors no matter the genomic status, the histological subtype or grade. Trametinib also strongly inhibited cell proliferation and induced AKT activation. Combined treatment with alpelisib plus trametinib reversed the AKT activation induced by trametinib and induced an additive inhibitory effect irrespective of the cell lines or tumor features. Co-targeting pathways seems promising and may be considered particularly for aggressive meningioma.

Molecular determinants of outcomes in meningiomas

Meningiomas are the most common intracranial primary tumor in adults. Surgery is the predominant therapeutic modality for symptomatic meningiomas. Although the majority of meningiomas are benign, there exists a subset of meningiomas that are clinically aggressive. Recent advances in genetics and epigenetics have uncovered molecular alterations that drive tumor meningioma biology with prognostic and therapeutic implications. In this review, we will discuss the advances on molecular determinants of therapeutic response in meningiomas to date and discuss findings of targeted therapies in meningiomas.

Advances in Molecular Biological and Translational Studies in World Health Organization Grades 2 and 3 Meningiomas: A Literature Review

The treatment of World Health Organization (WHO) grades 2 and 3 meningiomas remains difficult and controversial. The pathogenesis of high-grade meningiomas was expected to be elucidated to improve treatment strategies. The molecular biology of meningiomas has been clarified in recent years. High-grade meningiomas have been linked to NF2 mutations and 22q deletion. CDKN2A/B homozygous deletion and TERT promoter mutations are independent prognostic factors for WHO grade 3 meningiomas. In addition to 22q loss, 1p, 14p, and 9q loss have been linked to high-grade meningiomas. Meningiomas enriched in copy number alterations may be biologically invasive. Furthermore, several new comprehensive classifications of meningiomas have been proposed based on these molecular biological features, including DNA methylation status. The new classifications may have implications for treatment strategies for refractory aggressive meningiomas because they provide a more accurate prognosis compared to the conventional WHO classification. Although several systemic therapies, including molecular targeted therapies, may be effective in treating refractory aggressive meningiomas, these drugs are being tested. Systemic drug therapy for meningioma is expected to be developed in the future. Thus, this review aims to discuss the distinct genomic alterations observed in WHO grade 2 and 3 meningiomas, as well as their diagnostic and therapeutic implications and systemic drug therapies for high-grade meningiomas.

Clinical Significance of Molecular Alterations and Systemic Therapy for Meningiomas: Where Do We Stand?

Simple Summary

Meningiomas are the most frequent intracranial tumors and comprise a heterogeneous spectrum of diseases, ranging from small, asymptomatic tumors that do not need treatment to large, symptomatic ones causing seizures or neurological deficits that require surgery and/or radiotherapy. Systemic therapy is reserved for progressive or recurrent meningiomas when surgery and/or radiotherapy options have been exhausted, with only modest activity in terms of disease control and survival. Novel molecular alterations are correlated with grading, location, and prognosis of meningiomas. Moreover, some of these driver alterations regulate meningioma growth and progression and may be targeted by specific drugs that are under investigation in clinical trials. Lastly, the microenvironment surrounding meningiomas may also contribute to regulating tumor growth: in particular, PD-L1 and/or M2 macrophage expression may represent a target for immunotherapy.

Abstract

Meningiomas are common intracranial tumors that can be treated successfully in most cases with surgical resection and/or adjuvant radiotherapy. However, approximately 20% of patients show an aggressive clinical course with tumor recurrence or progressive disease, resulting in significant morbidity and increased mortality. Despite several studies that have investigated different cytotoxic agents in aggressive meningiomas in the past several years, limited evidence of efficacy and clinical benefit has been reported thus far. Novel molecular alterations have been linked to a particular clinicopathological phenotype and have been correlated with grading, location, and prognosis of meningiomas. In this regard, SMO, AKT, and PIK3CA mutations are typical of anterior skull base meningiomas, whereas KLF4 mutations are specific for secretory histology, and BAP1 alterations are common in progressive rhabdoid meningiomas. Alterations in TERT, DMD, and BAP1 correlate with poor outcomes. Moreover, some actionable mutations, including SMO, AKT1, and PIK3CA, regulate meningioma growth and are under investigation in clinical trials. PD-L1 and/or M2 macrophage expression in the microenvironment provides evidence for the investigation of immunotherapy in progressive meningiomas.

Clinical factors and outcomes of malignant meningioma: a population-based study

OBJECTIVE

We aimed to investigate prognostic factors and outcomes of malignant meningioma and to construct a nomogram model of survival.

METHODS

Patients with malignant meningioma were collected from the Surveillance, Epidemiology, and End Results database. The nomogram was developed for the 3-, 5-, and 8-year prediction of overall survival (OS) and cancer-specific survival (CSS). Harrell's concordance index (C-index) and decision curve analysis (DCA) were used to verify the predicted effect of the nomogram.

RESULTS

Between 1998 and 2016, 806 adult patients with histologically confirmed malignant meningioma were included. The mean age at diagnosis was 61.0 years (median 61.0 years), with a range of 19-104 years. Univariate analysis revealed that male gender, distant metastasis, and age ≥ 80 years as significant adverse factors for OS and CSS. These factors remained significance in the multivariate analysis. The nomogram demonstrated satisfactory discrimination, with a C-index value of 0.663 for OS and 0.654 for CSS, respectively. For both OS and CSS, the DCA curves indicated that the nomogram model performed better than other clinical variables.

CONCLUSION

Older age, male gender, distant metastasis, and radiotherapy were significantly related to poor prognosis; and extent of resection did not affect survival.

Gemcitabine Cooperates with Everolimus to Inhibit the Growth of and Sensitize Malignant Meningioma Cells to Apoptosis Induced by Navitoclax, an Inhibitor of Anti-Apoptotic BCL-2 Family Proteins

Simple Summary

Meningioma is the most common intracranial neoplasm derived from the arachnoid cap cells of the leptomeninges. Malignant meningioma is generally more aggressive than other meningioma and frequently recurs even after surgery and radiation therapy. Clinical trials have been performed on candidate drugs, including everolimus, an inhibitor of mammalian target of rapamycin. However, an effective standard systemic therapy has not yet been established and the prognosis of patients with malignant meningioma is still poor. We recently reported the radiosensitization effects of gemcitabine in malignant meningioma cells, which suggests its potential to enhance the efficacy of candidate drugs for meningioma. In the present study, we demonstrated that gemcitabine enhanced the therapeutic effects of everolimus in malignant meningioma cells, and these effects were further augmented by navitoclax, an inhibitor of anti-apoptotic BCL-2 family proteins, both in vitro and in vivo. The present results provide support for the clinical application of gemcitabine and navitoclax in combination with everolimus to the treatment of patients with malignant meningioma.

Abstract

Despite several clinical trials with encouraging findings, effective standard systemic therapies have yet to be established for malignant meningioma and the prognosis of these patients remains poor. Accumulating preclinical and clinical evidence suggests that gemcitabine is effective against malignant meningioma. To identify drugs with therapeutic effects that may be enhanced in combination with gemcitabine, we screened drugs that have been tested in preclinical and clinical trials for meningioma. In IOMM-Lee and HKBMM malignant meningioma cells, gemcitabine enhanced the growth inhibitory effects of the mTOR inhibitor everolimus, the clinical benefits of which have been demonstrated in patients with meningioma. The synergistic growth inhibitory effects of this combination were accompanied by cellular senescence characterized by an increase in senescence-associated β-galactosidase activity. To enhance the effects of this combination, we screened senolytic drugs that selectively kill senescent cells, and found that navitoclax, an inhibitor of anti-apoptotic BCL-2 family proteins, effectively reduced the number of viable malignant meningioma cells in combination with everolimus and gemcitabine by inducing apoptotic cell death. The suppression of tumor growth in vivo by the combination of everolimus with gemcitabine was significantly stronger than that by either treatment alone. Moreover, navitoclax, in combination with everolimus and gemcitabine, significantly reduced tumor sizes with an increase in the number of cleaved caspase-3-positive apoptotic cells. The present results suggest that the addition of gemcitabine with or without navitoclax to everolimus is a promising strategy that warrants further evaluation in future clinical trials for malignant meningioma.

Identification and Management of Aggressive Meningiomas

Meningiomas are common primary central nervous system tumors derived from the meninges, with management most frequently entailing serial monitoring or a combination of surgery and/or radiation therapy. Although often considered benign lesions, meningiomas can not only be surgically inaccessible but also exhibit aggressive growth and recurrence. In such cases, adjuvant radiation and systemic therapy may be required for tumor control. In this review, we briefly describe the current WHO grading scale for meningioma and provide demonstrative cases of treatment-resistant meningiomas. We also summarize frequently observed molecular abnormalities and their correlation with intracranial location and recurrence rate. We then describe how genetic and epigenetic features might supplement or even replace histopathologic features for improved identification of aggressive lesions. Finally, we describe the role of surgery, radiotherapy, and ongoing systemic therapy as well as precision medicine clinical trials for the treatment of recurrent meningioma.

A multi-institutional phase II trial of bevacizumab for recurrent and refractory meningioma

Background

Systemic therapies for refractory meningiomas are limited with no FDA-approved therapeutics. Vascular endothelial growth factor (VEGF) is a signaling protein associated with neovascularization, peritumoral edema, and meningioma tumorigenesis.

Methods

This phase II study investigates the efficacy of bevacizumab (BEV), a VEGF binding monoclonal antibody, in patients with progressive Grade I (G1M), Grade II (G2M), Grade III (G3M) meningioma, and other non-parenchymal tumors including vestibular schwannoma (n = 4) and hemangiopericytoma (n = 4) with the primary endpoint of progression-free survival rate at 6-months (PFS-6). Non-meningiomas were included with the respective meningioma grade in the analysis. Secondary endpoints include median overall survival (mOS) and response rate.

Results

Fifty Patients (26 women; median age 54 years; range 23-81), 42 with progressive meningioma were treated: 10 G1M, 20 G2M, and 12 G3M. Prior treatments include surgical resection (41 patients), radiosurgery (24 patients), external beam radiotherapy (28 patients), and chemotherapy (14 patients). Median infusions administered were 16 (range, 2-68). Response was graded using the Macdonald's criteria. PFS-6, median PFS, and mOS were 87%, 22 months, 35 months for G1M; 77%, 23 months, 41 months for G2M; and 46%, 8 months, 12 months for G3M. Best radiographic responses include stable disease (G1M: 100%; G2M: 85%; G3M: 82%); partial response (G1M: 0%; G2M: 5%; G3M: 0%) and progressive disease (G1M: 0%; G2M: 10%; G3M:18%). The most common toxicities were hypertension (n = 19, 42.2%), proteinuria (n = 16, 35.6%), and fatigue (n = 14, 31.1%).

Conclusion

This study showed BEV is well tolerated and appears to be a promising systemic treatment option for patients with recurrent and refractory meningiomas.

Chemotherapy and targeted therapies for meningiomas: what is the evidence?

PURPOSE OF REVIEW

Although most meningiomas are slow growing tumors mainly controlled by surgery with or without radiotherapy, aggressive meningiomas that fail these conventional treatments constitute a rare situation, a therapeutic challenge and an unmet need in neuro-oncology.

RECENT FINDING

Mutational landscape in recurrent high-grade meningiomas includes mainly NF2 mutation or 22q chromosomal deletion, whereas telomerase reverse transcriptase promoter, BAP-1 and CDK2NA mutations were also found in aggressive meningiomas. Pi3K-Akt-mTOR pathway is currently the most relevant intracellular signaling pathway target in meningiomas with preliminary clinical activity observed. Assessment of drug activity with progression free survival rate at 6 months is challenging in regard to meningioma growth rate heterogeneity, so that 3-dimensional growth rate before and during treatment could be considered in the future to selected new active drugs.

SUMMARY

Despite a low evidence level, some systemic therapies may be considered for patients with recurrent meningioma not amenable to further surgery or radiotherapy. In recurrent high-grade meningioma, everolimus-octreotide combination, bevacizumab, sunitinib and peptide receptor radionuclide therapy exhibit a signal of activity that may justify their clinical use. Despite a lack of clear signal of activity to date, immunotherapy may offer new perspectives in the treatment of these refractory tumors.

Biology and Treatment of Meningiomas: A Reappraisal

Meningiomas are largely indolent tumors with a benign clinical course, but a minority exhibit aggressive behavior characterized by rapid growth, neurologic deficits, and increased mortality. Identifying high-risk patients requiring intervention is challenging, but recent insights into meningioma biology provide a useful guide for decision making. Standard of care for recurrent or biologically aggressive tumors consists of surgery and radiation therapy. Systemic therapies targeting vascular endothelial growth factor signaling and somatostatin analogues are potential options for those with refractory disease but display only modest activity. New paradigms in meningioma clinical trial design provide hope for improved options in the future.

EANO guideline on the diagnosis and management of meningiomas

Meningiomas are the most common intracranial tumors. Yet, only few controlled clinical trials have been conducted to guide clinical decision making, resulting in variations of management approaches across countries and centers. However, recent advances in molecular genetics and clinical trial results help to refine the diagnostic and therapeutic approach to meningioma. Accordingly, the European Association of Neuro-Oncology (EANO) updated its recommendations for the diagnosis and treatment of meningiomas. A provisional diagnosis of meningioma is typically made by neuroimaging, mostly magnetic resonance imaging. Such provisional diagnoses may be made incidentally. Accordingly, a significant proportion of meningiomas, notably in patients that are asymptomatic or elderly or both, may be managed by a watch-and-scan strategy. A surgical intervention with tissue, commonly with the goal of gross total resection, is required for the definitive diagnosis according to the WHO classification. A role for molecular profiling including gene panel sequencing and genomic methylation profiling is emerging. A gross total surgical resection including the involved dura is often curative. Inoperable or recurrent tumors requiring treatment can be treated with radiosurgery, if the size or the vicinity of critical structures allows that, or with fractionated radiotherapy (RT). Treatment concepts combining surgery and radiosurgery or fractionated RT are increasingly used, although there remain controversies regard timing, type, and dosing of the various RT approaches. Radionuclide therapy targeting somatostatin receptors is an experimental approach, as are all approaches of systemic pharmacotherapy. The best albeit modest results with pharmacotherapy have been obtained with bevacizumab or multikinase inhibitors targeting vascular endothelial growth factor receptor, but no standard of care systemic treatment has been yet defined.

Receptor Tyrosine Kinases as Candidate Prognostic Biomarkers and Therapeutic Targets in Meningioma

Meningioma (MGM) is the most common type of intracranial tumor in adults. The validation of novel prognostic biomarkers to better inform tumor stratification and clinical prognosis is urgently needed. Many molecular and cellular alterations have been described in MGM tumors over the past few years, providing a rational basis for the identification of biomarkers and therapeutic targets. The role of receptor tyrosine kinases (RTKs) as oncogenes, including those of the ErbB family of receptors, has been well established in several cancer types. Here, we review histological, molecular, and clinical evidence suggesting that RTKs, including the epidermal growth factor receptor (EGFR, ErbB1), as well as other members of the ErbB family, may be useful as biomarkers and therapeutic targets in MGM.

Trabectedin for recurrent WHO grade 2 or 3 meningioma: a randomized phase 2 study of the EORTC Brain Tumor Group (EORTC-1320-BTG)

BACKGROUND

No systemic treatment has been established for meningioma progressing after local therapies.

METHODS

This randomized, multicenter, open-label, phase 2 study included adult patients with recurrent WHO grade 2 or 3 meningioma. Patients were 2:1 randomly assigned to intravenous trabectedin (1.5 mg/m 2 every three weeks) or local standard of care (LOC). The primary endpoint was progression-free survival (PFS). Secondary endpoints comprised overall survival (OS), objective radiological response, safety, quality of life (QoL) assessment using the QLQ-C30 and QLQ-BN20 questionnaires, and we performed tissue-based exploratory molecular analyses.

RESULTS

Ninety patients were randomized (n=29 in LOC, n=61 in trabectedin arm). With 71 events, median PFS was 4.17 months in the LOC and 2.43 months in the trabectedin arm (hazard ratio [HR]=1.42; 80% CI, 1.00-2.03; p=0.294) with a PFS-6 rate of 29.1% (95% CI, 11.9%-48.8%) and 21.1% (95% CI, 11.3%-32.9%), respectively. Median OS was 10.61 months in the LOC and 11.37 months in the trabectedin arm (HR=0.98; 95% CI, 0.54-1.76; p=0.94). Grade ≥3 adverse events occurred in 44.4% patients in the LOC and 59% of patients in the trabectedin arm. Enrolled patients had impeded global QoL and overall functionality and high fatigue before initiation of systemic therapy. DNA methylation class, performance status, presence of a relevant co-morbidity, steroid use, and right hemisphere involvement at baseline were independently associated with OS.

CONCLUSIONS

Trabectedin did not improve PFS and OS and was associated with higher toxicity than LOC treatment in patients with non-benign meningioma. Tumour DNA methylation class is an independent prognostic factor for OS.

Discovering the Molecular Landscape of Meningioma: The Struggle to Find New Therapeutic Targets

Meningiomas are the most common primary CNS tumors. They are usually benign but can present aggressive behavior in about 20% of cases. The genetic landscape of meningioma is characterized by the presence (in about 60% of cases) or absence of NF2 mutation. Low-grade meningiomas can also present other genetic alterations, particularly affecting SMO, TRAF7, KLF4 AKT1 and PI3KCA. In higher grade meningiomas, mutations of TERT promoter and deletion of CDKN2A/B seem to have a prognostic value. Furthermore, other genetic alterations have been identified, such as BAP1, DMD and PBRM1. Different subgroups of DNA methylation appear to be correlated with prognosis. In this review, we explored the genetic landscape of meningiomas and the possible therapeutic implications.

FORGE: A Novel Scoring System to Predict the MIB-1 Labeling Index in Intracranial Meningiomas

Simple Summary

Meningiomas are predominantly benign intracranial tumors, and surgical therapy represents the treatment of choice. However, the risk of recurrence and scheduling of follow-up intervals are significantly influenced by immunohistochemical items such as the MIB-1 labeling index. To date, it is not possible to integrate this essential information into the pre- or intraoperative surgical decision making. In the present study, we therefore analyzed baseline variables associated with the MIB-1 labeling index. We found four easily identifiable and routinely recorded risk factors for an increased MIB-1 index and developed a simple and quick-to-use score that allows us to estimate the risk of an elevated MIB-1 index prior to the surgical resection. Furthermore, this score seems to predict the progression-free survival in intracranial meningiomas. We believe that this score might us to more reliably guide patients in preoperative surgical strategy planning and postoperative follow-up scheduling.

Abstract

The MIB-1 index is an essential predictor of progression-free-survival (PFS) in meningioma. To date, the MIB-1 index is not available in preoperative treatment planning. A preoperative score estimating the MIB-1 index in patients with intracranial meningiomas has not been investigated so far. Between 2013 and 2019, 208 patients with tumor morphology data, MIB-1 index data, and plasma fibrinogen and serum C-reactive protein (CRP) data underwent surgery for intracranial WHO grade I and II meningioma. An optimal MIB-1 index cut-off value (≥6/<6) in the prediction of recurrence was determined by ROC curve analysis (AUC: 0.71; 95% CI: 0.55–0.87). A high MIB-1 index (≥6%) was present in 50 cases (24.0%) and was significantly associated with male sex, peritumoral edema, low baseline CRP, and low fibrinogen level in the multivariate analysis. A scoring system (“FORGE”) based on sex, peritumoral edema, preoperative CRP value, and plasma fibrinogen level supports prediction of the MIB-1 index (sensitivity 62%, specificity 79%). The MIB-1 labeling index and the FORGE score are significantly associated with an increased risk of poor PFS time. We suggest a novel score (“FORGE”) to preoperatively estimate the risk of an increased MIB-1 index (≥6%), which might help in surgical decision making and follow-up interval determination and inform future trials investigating inflammatory burden and proliferative activity.

Role of 3D volume growth rate for drug activity evaluation in meningioma clinical trials: the example of the CEVOREM study

BACKGROUND

We aimed to improve the assessment of the drug activity in meningioma clinical trials based on the study of the 3D volume growth rate (3DVGR) in a series of aggressive meningiomas. We secondarily aimed to correlate 3DVGR study with patient outcome.

METHODS

We performed a post hoc analysis based on volume data and 3DVGR extracted from CEVOREM study including 18 patients with 32 recurrent high-grade meningiomas and treated with everolimus and octreotide. The joint latent class model was used to classify tumor 3DVGR undertreatment.

RESULTS

Class 1 includes lesions responding to treatment with decrease in volume in the first 3 months, and then a stabilization thereafter (9.5% of tumors) (mean pretreatment 3DVGR = 6.13%/month; mean undertreatment 3DVGR = -18.7%/month within 3 first months and -0.14%/month after the 3 first months). Class 2 includes lesions considered as stable or with a slight increase in volume undertreatment (65.5%) (mean pretreatment 3DVGR = 6.09%/month; undertreatment 3DVGR = -0.09% within the first 3 months). Class 3 includes lesions without 3DVGR decrease (25%) (mean pretreatment 3DVGR = 46.9%/month; mean undertreatment 3DVGR = 19.2%/month within the first 3 months). Patients with class 3 lesions had a significantly worse progression-free survival (PFS) rate than class 1 and 2 ones.

CONCLUSIONS

Tumor 3DVGR could be helpful to detect early signal of drugs antitumoral activity or nonactivity. This volume response classification could help in the assessment of drug activity in tumors with mostly volume stabilization and rare response as aggressive meningiomas even with a low number of patients in complement to 6 months PFS.

Meningioma: not always a benign tumor. A review of advances in the treatment of meningiomas

Meningiomas are the most common primary intracranial tumors. The majority of meningiomas are benign, but they can present different grades of dedifferentiation from grade I to grade III (anaplastic/malignant) that are associated with different outcomes. Radiological surveillance is a valid option for low-grade asymptomatic meningiomas. In other cases, the treatment is usually surgical, aimed at achieving a complete resection. The use of adjuvant radiotherapy is the gold standard for grade III, is debated for grade II and is not generally indicated for radically resected grade I meningiomas. The use of systemic treatments is not standardized. Here we report a review of the literature on the clinical, radiological and molecular characteristics of meningiomas, available treatment strategies and ongoing clinical trials.

Advances in Multidisciplinary Management of Skull Base Meningiomas

The surgical management of Skull Base Meningiomas (SBMs) has radically changed over the last two decades. Extensive surgery for patients with SBMs represents the mainstream treatment; however, it is often challenging due to narrow surgical corridors and proximity to critical neurovascular structures. Novel surgical technologies, including three-dimensional (3D) preoperative imaging, neuromonitoring, and surgical instruments, have gradually facilitated the surgical resectability of SBMs, reducing postoperative morbidity. Total removal is not always feasible considering a risky tumor location and invasion of surrounding structures and brain parenchyma. In recent years, the use of primary or adjuvant stereotactic radiosurgery (SRS) has progressively increased due to its safety and efficacy in the control of grade I and II meningiomas, especially for small to moderate size lesions. Patients with WHO grade SBMs receiving subtotal surgery can be monitored over time with surveillance imaging. Postoperative management remains highly controversial for grade II meningiomas, and depends on the presence of residual disease, with optional upfront adjuvant radiation therapy or close surveillance imaging in cases with total resection. Adjuvant radiation is strongly recommended in patients with grade III tumors. Although the currently available chemotherapy or targeted therapies available have a low efficacy, the molecular profiling of SBMs has shown genetic alterations that could be potentially targeted with novel tailored treatments. This multidisciplinary review provides an update on the advances in surgical technology, postoperative management and molecular profile of SBMs.

Current experimental therapies for atypical and malignant meningiomas

INTRODUCTION

Atypical (WHO grade II) and malignant meningiomas (WHO Grade III) are a rare subset of primary intracranial tumors. Given their relatively high recurrence rate after surgical resection and radiotherapy, there has been a recent push to explore other adjuvant treatment options for these treatment-refractory tumors. Recent advances in molecular sequencing of tumors have elucidated new pathways and drug targets which are currently being studied. This article provides a thorough overview of novel investigational therapeutics including targeted therapy, immunotherapy, and new technological modalities for atypical and malignant meningiomas.

METHODS

We performed a comprehensive review of the available literature regarding preclinical and clinical evidence for emerging treatments for high grade meningiomas from 1980 to 2020 including contemporaneous clinical trials.

RESULTS

There is encouraging preclinical evidence regarding the efficacy of the emerging treatments discussed in this article. Several clinical trials are currently recruiting patients to translate targeted molecular therapy for meningiomas. Several clinical studies have suggested a clinical benefit of combinatorial treatment for these treatment-refractory tumors.

CONCLUSION

With numerous active clinical trials for high grade meningiomas, a meaningful improvement in the outcomes for these tumors may be on the horizon.

Brain-invasive meningiomas: molecular mechanisms and potential therapeutic options

Meningiomas are the most commonly diagnosed benign intracranial adult tumors. Subsets of meningiomas that present with extensive invasion into surrounding brain areas have high recurrence rates, resulting in difficulties for complete resection, substantially increased mortality of patients, and are therapeutically challenging for neurosurgeons. Exciting new data have provided insights into the understanding of the molecular machinery of invasion. Moreover, clinical trials for several novel approaches have been launched. Here, we will highlight the mechanisms which govern brain invasion and new promising therapeutic approaches for brain-invasive meningiomas, including pharmacological approaches targeting three major aspects of tumor cell invasion: extracellular matrix degradation, cell adhesion, and growth factors, as well as other innovative treatments such as immunotherapy, hormone therapy, Tumor Treating Fields, and biodegradable copolymers (wafers), impregnated chemotherapy. Those ongoing studies can offer more diversified possibilities of potential treatments for brain-invasive meningiomas, and help to increase the survival benefits for patients.

Regression of Intracranial Meningiomas Following Treatment with Cabozantinib

Recurrent meningiomas remain a substantial treatment challenge given the lack of effective therapeutic options aside from surgery and radiation therapy, which yield limited results in the retreatment situation. Systemic therapies have little effect, and responses are rare; the search for effective systemic therapeutics remains elusive. In this case report, we provide data regarding significant responses in two radiographically diagnosed intracranial meningiomas in a patient with concurrent thyroid carcinoma treated with cabozantinib, an oral multitarget tyrosine kinase inhibitor with potent activity against MET and VEGF receptor 2. Given the clinical experience supporting the role of VEGF agents as experimental therapeutics in meningioma and the current understanding of the biological pathways underlying meningioma growth, this may represent a new oral therapeutic alternative, warranting prospective evaluation.

Medical management of meningiomas

Meningiomas are the most frequently occurring primary brain tumors in adults, representing almost one-third of all primary central nervous system tumors. Several factors have been suggested as an underlying cause in the development of meningiomas, such as ionizing radiation (therapeutic or other incidental exposure), hormonal factors, and genetic predisposition syndromes. Other established factors associated with meningiomas include age, female gender, and those from non-Hispanic Black backgrounds. Though the 2016 World Health Organization Classification of Brain Tumors largely preserves the existing grading scheme for organization of meningioma, there is increasing understanding of the molecular factors underlying the development of meningioma, some of which now form the basis for active clinical investigation. The mainstay of treatment has been the combination of radiation therapy and surgery, with a limited role for systemic therapy due to low efficacy, short duration of treatment response, and lack of uniform response criteria. Similar to other primary and metastatic brain tumors, immune-based therapies hold promise and are still under investigation.

Multimodal management of surgery- and radiation-refractory meningiomas: an analysis of the French national tumor board meeting on meningiomas cohort

PURPOSE

Meningiomas represent the most frequent tumor of the central nervous system in adults. While most meningiomas are efficiently treated by surgery and radiotherapy/radiosurgery, there is a small portion of radiation- and surgery-refractory tumors for which there is no clear recommendation for optimal management. The French National Tumor Board Meeting on Meningiomas (NTBM) offers a glimpse on the current management of such patients.

METHODS

We retrospectively reviewed the charts of patients presented to the multidisciplinary Meeting between 2016 and 2019. We selected patients with a progressive disease after at least two treatments, including surgery and radiotherapy.

RESULTS

In this multicentric cohort of 86 cases, patients harbored 17 (19.8%) WHO Grade I, 48 (55.8%) WHO Grade II and 21 (24.4%) WHO Grade III tumors. The median number of treatments received before inclusion was 3 (range: 2 - 11). Following the Board Meeting, 32 patients (37.2%) received chemotherapy, 11 (12.8%) surgery, 17 (19.8%) radiotherapy, 14 (16.3%) watchful observation and 12 (13.9%) palliative care. After a mean follow-up of 13 months post-inclusion, 32 patients (37.2%) had died from their disease. The mean progression free survival was 27 months after radiotherapy, 10 months after surgery, 8.5 months after chemotherapy (Bevacizumab: 9 months - Octreotide/Everolimus: 8 months).

CONCLUSIONS

Surgery- and radiation-refractory meningiomas represent a heterogeneous group of tumors with a majority of WHO Grade II cases. If re-irradiation and redo-surgery are not possible, bevacizumab and octreotide-everolimus appear as a valuable option in heavily pre-treated patients considering the current EANO guidelines.

Influence of VEGF-A, VEGFR-1-3, and neuropilin 1-2 on progression-free: and overall survival in WHO grade II and III meningioma patients

Higher grade meningiomas tend to recur. We aimed to evaluate protein levels of vascular endothelial growth factor (VEGF)-A with the VEGF-receptors 1-3 and the co-receptors Neuropilin (NRP)-1 and -2 in WHO grade II and III meningiomas to elucidate the rationale for targeted treatments. We investigated 232 specimens of 147 patients suffering from cranial meningioma, including recurrent tumors. Immunohistochemistry for VEGF-A, VEGFR-1-3, and NRP-1/-2 was performed on tissue micro arrays. We applied a semiquantitative score (staining intensity x frequency). VEGF-A, VEGFR-1-3, and NRP-1 were heterogeneously expressed. NRP-2 was mainly absent. We demonstrated a significant increase of VEGF-A levels on tumor cells in WHO grade III meningiomas (p = 0.0098). We found a positive correlation between expression levels of VEGF-A and VEGFR-1 on tumor cells and vessels (p < 0.0001). In addition, there was a positive correlation of VEGF-A and VEGFR-3 expression on tumor vessels (p = 0.0034). VEGFR-2 expression was positively associated with progression-free survival (p = 0.0340). VEGF-A on tumor cells was negatively correlated with overall survival (p = 0.0084). The VEGF-A-driven system of tumor angiogenesis might still present a suitable target for adjuvant therapy in malignant meningioma disease. However, its role in malignant tumor progression may not be as crucial as expected. The value of comprehensive testing of the ligand and all receptors prior to administration of anti-angiogenic therapy needs to be evaluated in clinical trials.

Efficacy of 177Lu-Dotatate Therapy in the Treatment of Recurrent Meningioma

A 62-year-old man presented with a history of atypical meningioma (World Health Organization grade II) and recurrent as anaplastic meningioma (World Health Organization grade III). His previous treatments included multiple surgical resections, fractionated radiation therapy, stereotactic radiosurgery, everolimus/octreotide long-acting release, bevacizumab, and hydroxyurea. Magnetic resonance imaging revealed rapid volumetric progression over the prior 9 months, with a near tripling in size from 29.9 cm³ to 80.4 cm³. Indium In 111 octreotide scanning confirmed the presence of somatostatin receptors within the tumor. Lutetium Lu 177 dotatate was administered intravenously at a dose of 200 mCi per dose every 8 weeks for 4 cycles. Treatment was tolerated very well, with no notable adverse events. Tumor volume initially increased to 98.3 cm³ after cycle 1 of treatment and subsequently decreased to 91.2 cm³ after cycle 2. Eight months after treatment onset, the tumor volume remained stable (93.4 cm³).

Alteration of FOXM1 expression and macrophage polarization in refractory meningiomas during long-term follow-up

Malignant progression of grade I meningioma with a long latency period is rare. We experienced grade II/III meningiomas with refractoriness and recurrence from grade I meningiomas through multiple surgeries. Three patients with atypical/anaplastic meningioma experienced long-latent recurrence after initial surgery for grade I (meningothelial) meningioma without following adjuvant radiotherapy were included in the present study. Histological findings of the initial tumors in all cases (case 1, 2, and 3) revealed meningothelial meningioma with 1%, 5%, and 0.1% MIB-1 positive cells, respectively. Surprisingly, magnetic resonance imaging (MRI) detected a recurrent tumor 2, 12, and 12 years after the initial operation, respectively. Case 1 was atypical meningioma after third recurrence, and case 2 and 3 were anaplastic meningioma after second and third recurrence, respectively. The patient in case 2 received adjuvant radiotherapy. In case 2, the tumor recurred intracranial and distant metastasis to the lung with huge substantial pleural effusion was detected. To investigate the pathogenesis of malignant progression from benign to malignant meningioma, CD163/CD68 expression by immunohistochemically and FOXM1 mRNA expression by RT-PCR were compared using surgical specimens from initial and recurrent tumors in all three patients. The ratio of CD163/CD68 positivity and FOXM1 mRNA expression were increased in recurrent tumors compared with matched initial tumors. CD163 and FOXM1 expression levels were induced even in recurrent grade I meningioma, suggesting that macrophage polarization and pro-mitotic transcriptional factor might be associated with clinical behavior of meningioma and be useful as a prediction marker for malignant progression. Careful long-term follow-up is important for early diagnosis of malignant progression in meningiomas, even if grade I meningioma is completely resected. Development of a multidisciplinary approach including radiation and novel molecular targeted therapy is expected for recurrent and malignant meningiomas.

Review of Atypical and Anaplastic Meningiomas: Classification, Molecular Biology, and Management

Although the majority of meningiomas are slow-growing and benign, atypical and anaplastic meningiomas behave aggressively with a penchant for recurrence. Standard of care includes surgical resection followed by adjuvant radiation in anaplastic and partially resected atypical meningiomas; however, the role of adjuvant radiation for incompletely resected atypical meningiomas remains debated. Despite maximum treatment, atypical, and anaplastic meningiomas have a strong proclivity for recurrence. Accumulating mutations over time, recurrent tumors behave more aggressively and often become refractory or no longer amenable to further surgical resection or radiation. Chemotherapy and other medical therapies are available as salvage treatment once standard options are exhausted; however, efficacy of these agents remains limited. This review discusses the risk factors, classification, and molecular biology of meningiomas as well as the current management strategies, novel therapeutic approaches, and future directions for managing atypical and anaplastic meningiomas.

A Practical Overview on the Molecular Biology of Meningioma

PURPOSE OF REVIEW

Meningioma is a common intracranial neoplasm currently classified in 15 histologic subtypes across 3 grades of malignancy. First-choice therapy for meningioma is maximum safe resection for grade I tumors, and surgery plus optional and mandatory adjuvant radiotherapy for grade II and III, respectively, given the increased rate of recurrence even in the event of complete resection. The WHO 2016 histopathologic grading of meningioma has been questioned due to subjectivity and its controversial predictive power for recurrence.

RECENT FINDINGS

Novel DNA methylation profiling has simplified classification into six classes that seem to improve prognostic accuracy. We review five main topics of molecular biology research regarding tumorigenesis and natural history of meningioma from the clinician's perspective: the histopathologic diagnostic features and pitfalls of the current tumor classification; the molecular integrated diagnosis supported by identification of genetic alterations and DNA methylation profiling; the general landscape of the various signaling pathways involved in meningioma formation; the pathogenic theories of the peri-tumoral edema present in meningioma and its therapy implications; and a summarized review on the current treatments and plausible targeted therapies directed to meningioma. It seems likely that molecular assessment will be introduced within the next update of the WHO classification of meningiomas, acknowledging the promising value of DNA methylation profiling. This integrated diagnostic protocol will simplify tumor subtype categorization and provide improved accuracy in predicting recurrence and outcome. Although much effort is being done in identifying key gene mutations, and elucidating specific intracellular signaling pathways involved in meningioma tumorigenesis, effective targeted therapies for recurrent meningiomas are still lacking.

Molecular Mechanism and Approach in Progression of Meningioma

Meningioma is the most common tumor of the central nervous system, most of which is benign. Even after complete resection, a high rate of recurrence of meningioma is observed. From in-depth study of its pathogenesis, it has been found that a number of chromosomal variations and abnormal molecular signals are closely related to the occurrence and development of malignancy in meningioma, which may provide the theoretical basis and potential direction for accurate and targeted treatment. We have reviewed advances in chromosomal variations and molecular mechanisms involved in the progression of meningioma, and have highlighted the association with malignant biological behavior including cell proliferation, angiogenesis, increased invasiveness, and inhibition of apoptosis. In addition, the chemotherapy of meningioma is summarized and discussed.

Sensitivity of human meningioma cells to the cyclin-dependent kinase inhibitor, TG02

Standards of care for meningioma include surgical resection and radiotherapy whereas pharmacotherapy plays almost no role in this disease. We generated primary cultures from surgically removed meningiomas to explore the activity of a novel cyclin-dependent kinase inhibitor, TG02, in meningioma cell cultures. Tumor and cell cultures were characterized by mutation profiling and DNA methylation profiling. DNA methylation data were used to allot each sample to one out of six previously established meningioma methylation classes: benign (ben)-1, 2, 3, intermediate (int)-A, B, and malignant (mal). Four tumors assigned to the methylation class ben-2 showed the same class in culture whereas cultures from five non-ben-2 tumors showed a more malignant class in four patients. Cell cultures were uniformly sensitive to TG02 in the nanomolar range. Assignment of the cell cultures to a more malignant methylation class appeared to be more closely associated with TG02 sensitivity than assignment to a higher WHO grade of the primary tumors. Primary cell cultures from meningioma facilitate the investigation of the anti-meningioma activity of novel agents. TG02, an orally available cyclin-dependent kinase (CDK) inhibitor, warrants further exploration.

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Standards of care for meningioma include surgical resection and radiotherapy whereas pharmacotherapy plays almost no role.

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Primary cultures were established to explore the activity of a novel cyclin-dependent kinase inhibitor, TG02.

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DNA methylation data were used to assign each sample to one out of six previously established methylation classes.

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Cell cultures were uniformly sensitive to TG02 in the nanomolar range.

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Methylation class of cell cultures was associated stronger with TG02 sensitivity than WHO grade of the primary tumor.

Long-term therapy with Bevacizumab in a young patient affected by NF2. Stop or continue treatment? An update of a case report and review of the literature

Neurofibromatosis type 2 (NF2) is an autosomal dominant condition caused by pathogenic variants in the NF2 gene. To date, cytotoxic chemotherapy has no established role in the treatment of NF-2. Historical case reports of malignant schwannomas have documented responses to chemotherapies with cyclophosphamide, vincristine and doxorubicin, in patients who develop pulmonary metastases. Recently, several studies proposed the use of anti-HER2, anti-EGFR, anti-platelet-derived growth factor receptors. As reported in our previous review of the literature, vascular endothelial growth factor (VEGF) and its receptor VEGFR-1 have been detected in schwannomas with the best results. We described the case of a young patient with NF2 treated for long time with Bevacizumab. Here, we report the update of the previous case report.

A Retrospective Interventional Cohort Study to Assess the Safety and Efficacy of Sandostatin LAR for Treatment of Recurrent and/or Refractory Meningiomas

Background: Meningiomas are the most common adult primary intracranial tumors in the United States. Despite high recurrence rate of atypical and malignant subtypes, there is no approved drug indicated specifically for meningioma. Since the majority of meningiomas exhibit high density of somatostatin receptors subtypes, somatostatin analogs have been under close investigation. The aim of this study was to evaluate efficacy and safety of Sandostatin LAR (octreotide) in patients with progressive, and/or recurrent meningioma, and identify subset of patients who were more likely to benefit from this treatment.

Methods: A total of 43 patients ≥ 18 years old were included in the retrospective chart review. The patients underwent treatment with Sandostatin LAR (octreotide) from 01.01.2010 to 06.01.2017 at the University of California, Irvine after confirmation of the diagnosis. Six months progression free survival (PFS6) was defined as a primary endpoint, and the overall survival (OS), safety, and toxicity were identified as secondary endpoints.

Results: The OS for 6 months, 1, and 3 years for all WHO grades was 94.8, 88.1, and 67.0%, respectively. The PFS6 for WHO I, II, III, and all was 89.4, 89, 33.3, and 80% respectively. For patients with no prior surgeries, chemotherapy or radiation, the PFS6 was 88.9, 84.8, and 94.8%, respectively. Interestingly, the PFS6 was 90.5% for skull-based and 80% for 3–6 cm tumors. Patients with tumors in parasagittal location had PFS6 of 83.3% compared to PFS6 of 50.0% for patients with convexity tumors. Evaluation of PFS6 based on the effect of estrogen and progesterone on meningioma identified that ER-PR+ tumors had PFS6 of 87.8% while patients with ER-PR- meningiomas had PFS6 of 62.5%. Median TTP for WHO grade I, II, and III was 3.1, 2.40, and 0.26 years, respectively. Subgroup analysis showed that median TTP was 3.1 years for <3 cm tumors, 3.22 years for skull-based tumors, 2.37 years for patients with prior surgeries and 3.10 years for patients with no history of chemotherapy. History of radiation had no effect on median TTP. Sandostatin LAR (octreotide) was well-tolerated.

Conclusions:This is one of the largest retrospective analysis of meningioma patients treated with Sandostatin LAR (octreotide) suggesting that this treatment has minimal to no adverse events and could prolong overall survival, and progression free survival especially for patients with ER-PR+ tumors who underwent surgeries for small skull-based tumors.