Role of bevacizumab for treatment-refractory meningiomas: A systematic analysis and literature review

European Association of Neuro-Oncology guideline on molecular testing of meningiomas for targeted therapy selection

Meningiomas are the most common primary intracranial tumors of adults. For meningiomas that progress or recur despite surgical resection and radiotherapy, additional treatment options are limited due to a lack of proven efficacy. Meningiomas show recurring molecular aberrations, which may serve as predictive markers for systemic pharmacotherapies with targeted drugs or immunotherapy, radiotherapy, or radioligand therapy. Here, we review the evidence for a predictive role of a wide range of molecular alterations and markers including NF2, AKT1, SMO, SMARCE1, PIK3CA, CDKN2A/B, CDK4/6, TERT, TRAF7, BAP1, KLF4,ARID1/2, SUFU, PD-L1, SSTR2A, PR/ER, mTOR, VEGF(R), PDGFR, as well as homologous recombination deficiency, genomic copy number variations, DNA methylation classes, and combined gene expression profiles. In our assessment based on the established ESMO ESCAT (European Society for Medical Oncology Scale for Clinical Actionability of molecular Targets) evidence-level criteria, no molecular target reached ESCAT I ("ready for clinical use") classification, and only mTOR pathway activation and NF2 alterations reached ESCAT II ("investigational") classification, respectively. Our evaluations may guide targeted therapy selection in clinical practice and clinical trial efforts and highlight areas for which additional research is warranted.

Case report: Clonal evolution analysis of a rare case of meningioma lung metastases identifies actionable alterations in matched longitudinal tumour samples

Metastatic meningioma is rare, occurring in less than 1% of patients, and very few case studies have been reported, in particular for those that have spread to the lungs. Here we describe a rare case of metastatic meningioma to the lungs. Following a discussion at a medical oncology multi-disciplinary team meeting, whole genome sequencing was requested in November 2021 and discussed at a neurosurgical molecular tumor board in June 2022. Sequencing was performed on matched longitudinal collected samples of the primary tumor resection, the re-excised recurrent tumor after adjuvant radiation therapy, the lung metastases before treatment with sunitinib, and one paired blood sample for tumor-normal analysis. Whole genome characterization and clonal evolution analysis confirmed neurofibromatosis 2 (NF2) gene loss as the main driver of this cancer. In the same cancer clone as NF2, we identified a BRCA2 (p.E51K) mutation was present in all tumors, which may represent a potential driver event, though evidence supporting this is currently limited. Although this mutation is predicted to potentially influence homologous recombination, its clinical relevance as a biomarker for PARP inhibition remains speculative and requires further investigation. We also noted a SETD2 (p.S1885N) mutation that was present only in the recurrent tumor which was identified as a predicted biomarker of response to WEE1 inhibition. There was a stepwise increase in tumor mutational burden (TMB) from the primary meningioma to lung metastases, suggesting this patient may have been a candidate for immunotherapy.

Targeted therapy and immunotherapy for orbital and periorbital tumors: a major review

Traditionally, for patients who are poor candidates for surgery and/or radiotherapy, palliative chemotherapy is often offered but with significant toxic side effects. However, recent advancements in our understanding of tumor biology and molecular genetics have brought new understanding to the molecular pathways of certain tumors and cancers. This has ushered in a new era of precision medicine specific to a tumor or cancer treatment pathway (targeted therapy) or directed to host-tumor responses (immunotherapy). This article will focus on recent updates in the application of available targeted and immunotherapy for managing orbital and periorbital tumors and tumor-like conditions, which include cutaneous basal cell carcinoma, cutaneous squamous cell carcinoma, cutaneous melanoma, Merkel cell carcinoma, sebaceous gland carcinoma, solitary fibrous tumor, dermatofibrosarcoma protuberans, orbital meningioma, neurofibromatosis, Langerhans cell histiocytosis, ocular adnexal lymphoma, orbital lymphatic malformation, and adenoid cystic carcinoma.

Application of bevacizumab in the management of meningiomas: a systematic review and meta-analysis

Meningiomas are the most common intracranial lesions and constitute one-third of diagnoses. Surgical resection is the gold-standard treatment option. In case of treatment failure, therapeutic options are limited. Bevacizumab is a vascular endothelial growth factor ligand-binding monoclonal antibody that prevents angiogenesis. This study aims to investigate the efficacy and feasibility of bevacizumab in meningiomas On December 30, 2023, a systematic search was conducted according to PRISMA guidelines using the PubMed, Scopus, Web of Science, and Embase databases. This study is conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart. Our study included 12 studies, comprising 243 individuals and 310 tumors. Most of the studies were retrospective (80%). Most of the patients were male (47.9%). The bevacizumab was mostly administered intravenously at 10 mg/kg every two weeks (77.8%). The mean progression-free survival (PFS) and overall survival (OS) were 19.1 ± 4.7 and 23.9 ± 8.4 months, respectively. The response rate was 0.33 (95%CI: 0.14-0.60). The PFS-6, PFS-12, and PFS-24 were 0.80 (95% CI: 0.64-0.89), 0.66 (95%CI: 0.46-0.82), and 25% (95%CI: 0.16-0.37), respectively. The OS-6, OS-12, and OS-24 were 0.89 (95% CI: 0.80-0.96), 0.86 (95%CI: 0.65-0.95), and 0.48 (95%CI: 0.16-0.82), respectively. The meta-regression identified the total number of individuals, number of tumors, gender, WHO II/III, and prior resection as a possible source of heterogeneity for outcomes. This study highlights the effectiveness of bevacizumab in meningiomas, especially in refractory, high-grade, or neurofibromatosis patients.

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.

Intracranial meningiomas: an update of the 2021 World Health Organization classifications and review of management with a focus on radiation therapy

Meningiomas account for approximately one third of all primary intracranial tumors. Arising from the cells of the arachnoid mater, these neoplasms are found along meningeal surfaces within the calvarium and spinal canal. Many are discovered incidentally, and most are idiopathic, although risk factors associated with meningioma development include age, sex, prior radiation exposure, and familial genetic diseases. The World Health Organization grading system is based on histologic criteria, and are as follows: grade 1 meningiomas, a benign subtype; grade 2 meningiomas, which are of intermediately aggressive behavior and usually manifest histologic atypia; and grade 3, which demonstrate aggressive malignant behavior. Management is heavily dependent on tumor location, grade, and symptomatology. While many imaging-defined low grade appearing meningiomas are suitable for observation with serial imaging, others require aggressive management with surgery and adjuvant radiotherapy. For patients needing intervention, surgery is the optimal definitive approach with adjuvant radiation therapy guided by extent of resection, tumor grade, and location in addition to patient specific factors such as life expectancy. For grade 1 lesions, radiation can also be used as a monotherapy in the form of stereotactic radiosurgery or standard fractionated radiation therapy depending on tumor size, anatomic location, and proximity to dose-limiting organs at risk. Optimal management is paramount because of the generally long life-expectancy of patients with meningioma and the morbidity that can arise from tumor growth and recurrence as well as therapy itself.

SMARCE1-related meningiomas: A clear example of cancer predisposing syndrome

We report the case of a 16-year-old girl presenting with spinal clear-cell multiple meningiomas (CCMs). In view of this presentation, we sequenced a bioinformatic panel of genes associated with susceptibility to meningioma, identifying a germline heterozygous variant inSMARCE1. Somatic DNA investigations in the CCM demonstrated the deletion of the wild-type allele (loss of heterozygosity, LOH), supporting the causative role of this variant. Family segregation study detected the SMARCE1 variant in the asymptomatic father and in the asymptomatic sister who, nevertheless, presents 2 spinal lesions. Germline heterozygous loss-of-function (LoF) variants in SMARCE1, encoding a protein of the chromatin-remodeling complex SWI/SNF, have been described in few familial cases of susceptibility to meningioma, in particular the CCM subtype. Our case confirms the role of NGS in investigating predisposing genes for meningiomas (multiple or recurrent), with specific regard to SMARCE1 in case of pediatric CCM. In addition to the age of onset, the presence of familial clustering or the coexistence of multiple synchronous meningiomas also supports the role of a genetic predisposition that deserves a molecular assessment. Additionally, given the incomplete penetrance, it is of great importance to follow a specific screening or follow-up program for symptomatic and asymptomatic carriers of pathogenic variants in SMARCE1.

Top advances of the year: Neuro-oncology

Management of brain tumors has been challenging given the limited therapeutic options and disabling morbidities associated with central nervous system (CNS) dysfunction. This review focuses on recent developments in the field, with an emphasis on clinical management. The growing clinical trials landscape reflects advanced insights into cancer immunology and genomics and the need to address molecular and clinical heterogeneity. Recent phase 3 trials investigating anti-PD-1 immunotherapies, particularly nivolumab, have failed to demonstrate improved survival in glioblastoma, underscoring the need to better understand the complexity of CNS immunologic surveillance. Conversely, targeted therapies have accounted for several US Food and Drug Administration approvals extended to brain tumors, particularly therapies directed to BRAF V600E mutations and TRAK fusions, underscoring a need to routinely screen patients for these rare molecular abnormalities. In primary CNS lymphoma, attention has turned to long-term outcomes of consolidation therapies, and recent studies have highlighted the excellent disease control afforded by high-dose chemotherapy and stem cell transplantation. Meningiomas remain a focus of investigations, with preliminary promising results observed with octreotide combined with mTOR inhibition, and immunotherapy with single-agent pembrolizumab. Finally, proton radiotherapy has emerged as a novel alternative for leptomeningeal metastases from solid tumors, which can now be treated more safely with craniospinal irradiation and monitored by the enumeration of circulating tumor cells in the cerebrospinal fluid as a biomarker. Taken together, these incremental advances have improved outcomes in select brain tumor patient populations, whereas ongoing clinical trials hold the promise of meaningful advances and breakthroughs for larger proportions of patients with brain tumors.

Prognostic significance of telomerase reverse transcriptase promoter gen mutations in high grade meningiomas

Introduction: Mutations in the promoter region of telomerase reverse transcriptase occur frequently in meningiomas. Objective: To estimate the prognostic importance of telomerase reverse transcriptase mutations in Colombian patients with grades II and III meningioma. Materials and methods: This was a multicenter retrospective cohort study of patients diagnosed with refractory or recurrent WHO grades II and III meningiomas, recruited between 2011 and 2018, and treated with systemic therapy (sunitinib, everolimus ± octreotide, and bevacizumab). Mutation status of the telomerase reverse transcriptase promoter was established by PCR. Results: Forty patients were included, of which telomerase reverse transcriptase mutations were found in 21 (52.5%), being C228T and C250T the most frequent variants with 87.5 % and 14.3 %, respectively. These were more frequent among patients with anaplastic meningiomas (p=0.18), with more than 2 recurrences (p=0.04); and in patients with parasagittal region and anterior fossa lesions (p=0.05). Subjects characterized as having punctual mutations were more frequently administered with everolimus, sunitinib and bevacizumab drug series (p=0.06). Overall survival was 23.7 months (CI95% 13.1-34.2) and 43.4 months (CI95% 37.5-49.3; p=0.0001) between subjects with and without mutations, respectively. Multivariate analysis showed that the number of recurrences and the presence of telomerase reverse transcriptase mutations were tthe only variables that negatively affected overall survival. Conclusions: Mutations in telomerase reverse transcriptase allows the identification of high-risk patients and could be useful in the selection of the best medical treatment.

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.

Potential Molecular Mechanisms of Recurrent and Progressive Meningiomas: A Review of the Latest Literature

Meningiomas, the most frequent primary intracranial tumors of the central nervous system in adults, originate from the meninges and meningeal spaces. Surgical resection and adjuvant radiation are considered the preferred treatment options. Although most meningiomas are benign and slow-growing, some patients suffer from tumor recurrence and disease progression, eventually resulting in poorer clinical outcomes, including malignant transformation and death. It is thus crucial to identify these "high-risk" tumors early; this requires an in-depth understanding of the molecular and genetic alterations, thereby providing a theoretical foundation for establishing personalized and precise treatment in the future. Here, we review the most up-to-date knowledge of the cellular biological alterations involved in the progression of meningiomas, including cell proliferation, neo-angiogenesis, inhibition of apoptosis, and immunogenicity. Focused genetic alterations, including chromosomal abnormalities and DNA methylation patterns, are summarized and discussed in detail. We also present latest therapeutic targets and clinical trials for meningiomas' treatment. A further understanding of cellular biological and genetic alterations will provide new prospects for the accurate screening and treatment of recurrent and progressive meningiomas.

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

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.

Efficacy of Bevacizumab in High-Grade Meningiomas: A Retrospective Clinical Study

OBJECTIVE

We investigated the role of bevacizumab (BV) in high-grade meningiomas (HGMs) by retrospective analysis.

METHODS

We retrospectively analyzed the clinical data of 139 patients with HGMs. The chi-square test was used to compare progression-free survival (PFS) and overall survival (OS) between patients who received BV and those who did not. According to whether they received BV treatment, we divided the patients into the BV group and non-BV group, and the effect of BV on PFS and OS was compared. In addition, we compared Karnofsky performance status (KPS) and steroid doses between the BV and non-BV groups.

RESULTS

There were statistically differences in PFS and OS between the BV and non-BV groups at 12 and 36 months after surgery (P<0.05). However, there was no significant difference in PFS and OS between the two groups at 60 months postoperatively (P>0.05). Using survival curves drawn by the Kaplan Meier method, we found that the PFS and OS of the BV group were greater than those of the non-BV group, and the difference was statistically significant (P<0.05).

CONCLUSION

BV could improve PFS and OS at 12 and 36 months after surgery in patients with HGMs. In addition, BV was associated with lower preoperative steroid use.

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.

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.

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.

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.

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.

The controversial role of Bevacizumab in the treatment of patients with intracranial meningioma: a comprehensive literature review

Introduction: Meningiomas represent the most common primary intracranial tumors. Today, surgical resection, followed by radiotherapy when indicated, is still the treatment of choice. In recent years, distinct oncogenic pathways have been identified, laying the foundations of new personalized targeted therapies.Areas covered: The aim of this study was to highlight the effects, complications, possible associations with other therapeutic approaches and multi-parametric outcome evaluation of Bevacizumab for the treatment of meningiomas. A literature review according to PRISMA criteria regarding the role of Bevacizumab for the treatment of various WHO grades of meningiomas was performed. 15 relevant papers, including 6 retrospective clinical trial series, 3 prospective trials, and 6 single patient case reports for a total of 134 patients and 211 meningiomas were include.Expert opinion: Because of the lack of strong clinical evidence about improved survival and related toxicity, the use of Bevacizumab for the treatment of meningiomas should be carefully evaluated. Further exploration, ideally with randomized controlled trials, is needed to better define the role of this drug in the treatment of meningiomas.

Identification of epithelial membrane protein 2 (EMP2) as a molecular marker and correlate for angiogenesis in meningioma

PURPOSE

Although intracranial meningiomas are the most common primary brain tumor in adults, treatment options are few and have traditionally been limited to surgical resection and radiotherapy. Additional targeted therapies and biomarkers are needed, especially as complete surgical resection is frequently not feasible in many patients.

METHODS

Non-pathologic brain tissue from 3 patients undergoing routine autopsies and tumor specimens from 16 patients requiring surgical resection for meningioma were collected. EMP2 protein expression was evaluated by immunohistochemistry and western blot analysis. EMP2 mRNA expression was also investigated using surgical specimens and validated by analysis of several independent NCBI GEO databases.

RESULTS

EMP2 mRNA expression levels were found to be higher in meningioma relative to non-pathologic meninges (P = 0.0013) and brain (P = 0.0011). Concordantly, strong EMP2 protein expression was demonstrated in 100% of meningioma specimens from all 16 patients, with no observable protein expression in normal brain tissue samples from 3 subjects (P < 0.001). EMP2 expression was confirmed by western blot analysis in five samples, with EMP2 protein intensity positively correlating with histologic staining score (R² = 0.780; P = 0.047). No association was found between EMP2 mRNA or protein levels and WHO grade or markers of proliferation. However, EMP2 expression was positively associated with an angiomatous pattern on histologic evaluation (P = 0.0597), VEGF-A mRNA expression (P < 0.001), and clinical markers of tumor vascularity such as operative blood loss (P = 0.037).

CONCLUSIONS

EMP2 is not found in normal brain tissue, yet has shown consistently high mRNA and protein expression in meningiomas, and may serve as a useful molecular marker for these tumors.

Clinical Outcomes of Recurrent Intracranial Meningiomas Treated with Proton Beam Reirradiation

Purpose

Recurrent meningiomas remain therapeutically challenging, often progressive despite multimodality salvage. There are limited data guiding reirradiation (reRT), and proton beam radiation therapy (PBRT) offers a potential advantage owing to lower integral brain dose.

Patients and Methods

We retrospectively conducted a review of 16 patients who received PBRT reRT for recurrent meningiomas. Kaplan-Meier and proportional hazards were used to determine post-PBRT progression-free survival (PFS) and overall survival (OS) and to evaluate clinical predictors.

Results

At diagnosis, 7 (44%), 8 (50%), and 1 (6%) patient had World Health Organization (WHO) grade I, II and III tumors, respectively. All received prior radiation therapy (RT) to a median of 54 Gy (range 13-65.5). Median time to PBRT reRT after prior RT was 5.8 years (range 0.7-18.7). Median PBRT dose was 60 Gy(RBE) (range 30-66.6), and median planning tumor volume (PTV) was 76 cm³ (range 8-249). Median follow-up was 18.8 months. At last follow-up, 7 intracranial recurrences (44%) and 3 disease-related deaths (19%) were found. Median cohort PFS was 22.6 months, with 1- and 2-year PFS of 80% and 43%, respectively. Median OS was not achieved, with 1- and 2-year OS of 94% and 73%; all deaths were felt to be related to meningioma. Patients with initially grade I tumors had improved PFS versus higher grade (Hazard Ratio, HR = 0.23, P = .03) with 1- and 2-year PFS estimates of 100% versus 71% and 75% versus 29%, respectively. Longer interval between prior RT and PBRT also predicted improved PFS (P = .03) and OS (P = .049). Overall late grade 3+ toxicity rate was 31%. Two patients (13%) developed radionecrosis at 6 and 16 months after PBRT; only 1 was symptomatic.

Conclusions

This is the first series specifically analyzing PBRT alone as a reRT strategy for recurrent meningioma. We report fair intracranial control with low rates of radionecrosis at 1 year after reRT. However, strategies to achieve durable outcomes are needed, particularly for high-grade tumors.

Bevacizumab in refractory higher-grade and atypical meningioma: the current state of affairs

INTRODUCTION

Historically, systemic agents had shown limited efficacy in meningioma, at the expense of significant pharmacologic and/or financial toxicity. As meningiomas are highly vascularized, they might derive benefit from antiangiogenic therapy.

AREAS COVERED

This review summarizes the literature regarding bevacizumab pharmacology, safety and efficacy in patients with refractory meningioma. We have searched PubMed/Medline database for pertinent articles published from inception to 1 September 2018.

EXPERT COMMENTARY

Results of two prospective phase II trials, supported by several retrospective cohorts, suggest a clinical benefit for the vascular endothelial growth factor inhibitor bevacizumab in meningiomas refractory to surgery and radiation therapy. This agent has a tolerable toxicity profile and seems more effective in higher-grade histologies and atypical meningioma, although responses in low-grade meningiomas have also been documented. Our conclusions are restricted due to a small size and lack of control in the prospective trials as well as the retrospective design of other studies. Further study of bevacizumab in refractory higher-grade meningiomas seems warranted.