Phase II study of Gleevec® plus hydroxyurea (HU) in adults with progressive or recurrent meningioma

Meningioma: International Consortium on Meningiomas consensus review on scientific advances and treatment paradigms for clinicians, researchers, and patients

Meningiomas are the most common primary intracranial tumors in adults and are increasing in incidence due to the aging population and increased access to neuroimaging. While most exhibit nonmalignant behavior, a subset of meningiomas are biologically aggressive and are associated with treatment resistance, resulting in significant neurologic morbidity and even mortality. In recent years, meaningful advances in our understanding of the biology of these tumors have led to the incorporation of molecular biomarkers into their grading and prognostication. However, unlike other central nervous system (CNS) tumors, a unified molecular taxonomy for meningiomas has not yet been established and remains an overarching goal of the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy-Not Official World Health Organization (cIMPACT-NOW) working group. Additionally, clinical equipoise still remains on how specific meningioma cases and patient populations should be optimally managed. To address these existing gaps, members of the International Consortium on Meningiomas including field-leading experts, have prepared this comprehensive consensus narrative review directed toward clinicians, researchers, and patients. Included in this manuscript are detailed overviews of proposed molecular classifications, novel biomarkers, contemporary treatment strategies, trials on systemic therapies, health-related quality-of-life studies, and management strategies for unique meningioma patient populations. In each section, we discuss the current state of knowledge as well as ongoing clinical and research challenges to road map future directions for further investigation.

Domestic Animal Models of Central Nervous System Tumors: Focus on Meningiomas

Intracranial primary tumors (IPTs) are aggressive forms of malignancies that cause high mortality in both humans and domestic animals. Meningiomas are frequent adult IPTs in humans, dogs, and cats, and both benign and malignant forms cause a decrease in life quality and survival. Surgery is the primary therapeutic approach to treat meningiomas, but, in many cases, it is not resolutive. The chemotherapy and targeted therapy used to treat meningiomas also display low efficacy and many side effects. Therefore, it is essential to find novel pharmacological approaches to increase the spectrum of therapeutic options for meningiomas. This review analyzes the similarities between human and domestic animal (dogs and cats) meningiomas by evaluating the molecular and histological characteristics, diagnosis criteria, and treatment options and highlighting possible research areas to identify novel targets and pharmacological approaches, which are useful for the diagnosis and therapy of this neoplasia to be used in human and veterinary medicine.

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.

Exploring the Past, Present, and Future of Anti-Angiogenic Therapy in Glioblastoma

Glioblastoma, a WHO grade IV astrocytoma, constitutes approximately half of malignant tumors of the central nervous system. Despite technological advancements and aggressive multimodal treatment, prognosis remains dismal. The highly vascularized nature of glioblastoma enables the tumor cells to grow and invade the surrounding tissue, and vascular endothelial growth factor-A (VEGF-A) is a critical mediator of this process. Therefore, over the past decade, angiogenesis, and more specifically, the VEGF signaling pathway, has emerged as a therapeutic target for glioblastoma therapy. This led to the FDA approval of bevacizumab, a monoclonal antibody designed against VEGF-A, for treatment of recurrent glioblastoma. Despite the promising preclinical data and its theoretical effectiveness, bevacizumab has failed to improve patients' overall survival. Furthermore, several other anti-angiogenic agents that target the VEGF signaling pathway have also not demonstrated survival improvement. This suggests the presence of other compensatory angiogenic signaling pathways that surpass the anti-angiogenic effects of these agents and facilitate vascularization despite ongoing VEGF signaling inhibition. Herein, we review the current state of anti-angiogenic agents, discuss potential mechanisms of anti-angiogenic resistance, and suggest potential avenues to increase the efficacy of this therapeutic approach.

The Role of Pharmacotherapy in Treatment of Meningioma: A Systematic Review

The safety and efficacy of various pharmacotherapeutic regimens on refractory meningiomas have been the focus of investigations. We present a comprehensive review of the previous efforts and the current state of ongoing clinical trials. A PRISMA-compliant review of the MEDLINE and ClinicalTrial.gov databases of the National Library of Medicine were performed. The primary outcomes of interest for included articles were radiographic response, overall survival, progression-free survival, six-month progression-free survival, and adverse events. Overall, 34 completed trials and 27 ongoing clinical trials were eligible. Six-month progression-free survival was reported in 6-100% of patients in the completed studies. Hematological disorders were the most common adverse events. Of the ongoing clinical trials identified, nine studies are phase I clinical trials, eleven are phase II trials, two are phase I and II trials, one is phase II and III, and two trials do not have a designated phase. Currently, there is no effective chemotherapy for refractory or recurrent meningiomas. Several promising targeted agents have been developed and are currently being investigated in the hope of identifying novel therapeutic strategies for the treatment of this pathology.

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.

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.

Management of Recurrent Meningiomas: State of the Art and Perspectives

Simple Summary

Intracranial meningiomas account for 30% to 40% of the primary lesions of the central nervous system. Surgery is the mainstay treatment whenever symptoms related to an intra-cranial meningioma are encountered. However, the management of recurrences after initial surgery, which are not uncommon, is still a matter of debate. Here, we present the alternatives described in the management of meningioma recurrence (radiotherapy, stereotaxic radiosurgery, protontherapy, and chemotherapy, among others). Their overall results are compared to surgery and future perspectives are presented.

Abstract

Background: While meningiomas often recur over time, the natural history of repeated recurrences and their management are not well described. Should recurrence occur, repeat surgery and/or use of adjuvant therapeutic options may be necessary. Here, we summarize current practice when it comes to meningioma recurrence after initial surgical management. Methods: A total of N = 89 articles were screened. N = 41 articles met the inclusion criteria and N = 16 articles failed to assess management of meningioma recurrence. Finally, N = 24 articles were included in our review. Results: The articles were distributed as follows: studies on chemotherapy (N = 14), radiotherapy, protontherapy, and stereotaxic radiosurgery (N = 6), boron-neutron capture therapy (N = 2) and surgery (N = 3). No study seems to provide serious alternatives to surgery in terms of progression-free and overall survival. Recurrence can occur long after the initial surgery and also affects WHO grade 1 meningiomas, even after initial gross total resection at first surgery, emphasizing the need for a long-term and comprehensive follow-up. Conclusions: Surgery still seems to be the state-of-the-art management when it comes to meningioma recurrence, since none of the non-surgical alternatives show promising results in terms of progression-free and overall survival.

[Targeted Drug Therapy for Intracranial Tumors]

Intracranial tumors seriously affect the physical and mental health of humans. Due to variations in the nature and the growth site of tumors, individualized and specific treatment of patients with intracranial tumor has become a hotspot topic of research, and targeted drug therapy of intracranial tumors, an important subspecialty of precision medicine, has become a key issue that scientists are working hard to tackle. At present, the rapid development in molecular biology and genomics has provided corresponding targets for precision therapies of tumors. However, the blood-brain barrier and blood-tumor barrier prevent drugs from reaching intracranial targets. Therefore, finding effective ways to elevate the concentration of intracranial drugs has become the key issue concerning existing targeted therapies for intracranial tumors. Herein, we reviewed the current status of targeted drug therapy for different intracranial tumors and discussed their efficacy, intending to provide new perspectives for the treatment of intracranial tumors with targeted drugs in the future.

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.

Evaluation of a procaspase-3 activator with hydroxyurea or temozolomide against high-grade meningioma in cell culture and canine cancer patients

BACKGROUND

High-grade meningioma is an aggressive type of brain cancer that is often recalcitrant to surgery and radiotherapy, leading to poor overall survival. Currently, there are no FDA-approved drugs for meningioma, highlighting the need for new therapeutic options, but development is challenging due to the lack of predictive preclinical models.

METHODS

To leverage the known overexpression of procaspase-3 in meningioma, PAC-1, a blood-brain barrier penetrant procaspase-3 activator, was evaluated for its ability to induce apoptosis in meningioma cells. To enhance the effects of PAC-1, combinations with either hydroxyurea or temozolomide were explored in cell culture. Both combinations were further investigated in small groups of canine meningioma patients and assessed by MRI, and the novel apoptosis tracer, [18F]C-SNAT4, was evaluated in patients treated with PAC-1 + HU.

RESULTS

In meningioma cell lines in culture, PAC-1 + HU are synergistic while PAC-1 + TMZ show additive-to-synergistic effects. In canine meningioma patients, PAC-1 + HU led to stabilization of disease and no change in apoptosis within the tumor, whereas PAC-1 + TMZ reduced tumor burden in all three canine patients treated.

CONCLUSIONS

Our results suggest PAC-1 + TMZ as a potentially efficacious combination for the treatment of human meningioma, and also demonstrate the utility of including pet dogs with meningioma as a means to assess anticancer strategies for this common brain tumor.

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.

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.

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.

Basis for Immunotherapy for Treatment of Meningiomas

Meningiomas are common tumors that account for approximately one third of CNS tumors diagnosed every year. They are classified by the World Health Organization in grades I-III. Higher grades have an increased rate of growth, invasiveness, rate of recurrence, and worse outcomes than lower grades. Most meningiomas are grade I, while ~18% of meningiomas are grade II and III in hospital-based series. Meningiomas are typically "benign" tumors that are treated with surgery and radiation. However, when they recur or are unresectable, treatment options are very limited, especially since they are chemotherapy-resistant. Recent advances in the treatment of cancers with immunotherapy have focused on checkpoint blockade as well as other types of immunotherapy. There is emerging evidence supporting the use of immunotherapy as a potentially effective treatment strategy for meningioma patients. The immune microenvironment of meningiomas is a complex interplay of genetic alterations, immunomodulatory protein expression, and tumor-immune cell interactions. Meningiomas are known to be infiltrated by immune cells including microglia, macrophages, B-cells, and T-cells. Several mechanisms contribute to decreased an ti-tumor immune response, allowing tumor growth and evasion of the immune system. We discuss the most current knowledge on the immune micro-environment of meningiomas, preclinical findings of immunotherapy in meningiomas, meningioma immunotherapy clinical trials, and also offer insight into future prospects for immunotherapies in meningiomas.

An Overview of Managements in Meningiomas

Meningioma is the most frequent primary tumor of the central nervous system. Important advances have been achieved in the treatment of meningioma in recent decades. Although most meningiomas are benign and have a good prognosis after surgery, clinicians often face challenges when the morphology of the tumor is complicated or the tumor is close to vital brain structures. At present, the longstanding treatment strategies of meningioma are mainly surgery and radiotherapy. The effectiveness of systemic therapy, such as chemotherapy or targeted therapy, has not been confirmed by big data series, and some clinical trials are still in progress. In this review, we summarize current treatment strategies and future research directions for meningiomas.

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.

Treatment of a Woman with Inoperable Meningioma Using Mifepristone for 26 Years

Meningioma treatment includes observation of its growth or surgery with or without associated radiotherapy. However, drug treatment can be used for tumors deemed inoperable because of their size and location. Due to the presence of progesterone receptors, the use of antiprogestin mifepristone is recommended. This study describes a case of inoperable meningioma treated with mifepristone for 26 years without interruption. The patient is a 45-year-old woman diagnosed with plaque meningioma, extending from the bottom of her right orbit, through the length of the small wing of the sphenoid, part of the large wing of the sphenoid, especially near the superior orbital fissure, and at the ceiling of the orbit. As this meningioma was considered inoperable, treatment with 200 mg oral mifepristone was administered uninterruptedly for 26 years. This treatment initially halted the growth of the meningioma and subsequently resulted in a small reduction of its volume; however, the meningioma has persisted until the last evaluation. After five years of mifepristone use, hydroxyurea was added for nine months but was discontinued due to anemia and leucopenia. In conclusion, mifepristone was useful for the survival of the patient for those 26 years. The drug interfered with the natural history of the meningioma, which generally evolves to death in such long follow-up durations without associated surgery or radiation therapy.

Medical management of meningioma in the era of precision medicine

Surgery is curative for most meningiomas, but a minority of these tumors recur and progress after resection. Initial trials of medical therapies for meningioma utilized nonspecific cytotoxic chemotherapies. The presence of hormone receptors on meningioma ushered in trials of hormone-mimicking agents. While these trials expanded clinical understanding of meningioma, they ultimately had limited efficacy in managing aggressive lesions. Subsequent detection of misregulated proteins and genomic aberrancies motivated the study of therapies targeting specific biological disturbances observed in meningioma. These advances led to trials of targeted kinase inhibitors and immunotherapies, as well as combinations of these agents together with chemotherapies. Prospective trials currently recruiting participants are testing a diverse range of medical therapies for meningioma, and some studies now require the presence of a specific protein alteration or genetic mutation as an inclusion criterion. Increasing understanding of the unique and heterogeneous nature of meningiomas will continue to spur the development of novel medical therapies for the arsenal against aggressive tumors.

Emerging Medical Treatments for Meningioma in the Molecular Era

Meningiomas are the most common type of primary central nervous system tumors. Approximately, 80% of meningiomas are classified by the World Health Organization (WHO) as grade I, and 20% of these tumors are grade II and III, considered high-grade meningiomas (HGMs). Clinical control of HGMs, as well as meningiomas that relapse after surgery, and radiation therapy is difficult, and novel therapeutic approaches are necessary. However, traditional chemotherapies, interferons, hormonal therapies, and other targeted therapies have so far failed to provide clinical benefit. During the last several years, next generation sequencing has dissected the genetic heterogeneity of meningioma and enriched our knowledge about distinct oncogenic pathways driving different subtypes of meningiomas, opening up a door to new personalized targeted therapies. Molecular classification of meningioma allows a new design of clinical trials that assign patients to corresponding targeted agents based on the tumor genetic subtypes. In this review, we will shed light on emerging medical treatments of meningiomas with a particular focus on the new targets identified with genomic sequencing that have led to clinical trials testing novel compounds. Moreover, we present recent development of patient-derived preclinical models that provide platforms for assessing targeted therapies as well as strategies with novel mechanism of action such as oncolytic viruses.

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

Background

Meningiomas are the most prevalent primary tumor of the central nervous system (CNS), and although the majority of these neoplasms are classified as benign, nearly one fourth of the lesions display an aggressive profile characterized by pleomorphic histology, high recurrence rates, and overall resistance to standard treatment. Despite the ubiquitous nature of these tumors, no adjuvant therapeutic regimen has been identified which effectively controls disease recurrence and progression after surgery and radiation, leading to a dismal prognosis in this patient population. The primary focus of this research study is, hence, to assess the recently emerging use of bevacizumab, an anti-angiogenic agent, in the treatment of meningiomas. This systematic literature review analyzes the efficacy and safety of therapeutic bevacizumab for treatment-refractory meningiomas.

Methods

A systematic PubMed search was conducted according to PRISMA guidelines to identify all relevant reports investigating the anti-angiogenic agent bevacizumab in the treatment of intracranial meningiomas. The reported parameters from pertinent retrospective reviews, prospective studies, and case studies were volumetric reduction, radiographic response, clinical stability, overall survival (OS), and progression free survival (PFS) measured at 6 and 12 months postinitiation of treatment. Complications were cataloged based on the range and severity of the therapy-related toxicities.

Results

A total of 11 articles, 5 retrospective series, 2 prospective trials, and 4 case reports, reporting on a total of 92 patients, were included in this review. The use of bevacizumab therapy for intracranial meningiomas demonstrated median overall PFS of 16.8 months (range: 6.5-22 months) and PFS-6 of 73% (range: 44%-93%).

Conclusions

Therapeutic bevacizumab, either alone or with combination chemotherapies, for select patient populations with recurrent or progressive meningiomas, offers a treatment option that confers improved overall progression-free survival. To assess OS parameters, larger randomized controlled trials assessing the use of anti-angiogenic agents for recurrent/progressive meningiomas are warranted.

Systemic therapy for recurrent meningioma

INTRODUCTION

Meningioma comprise 20-30% of all primary brain tumors. Notwithstanding surgery and radiotherapy, a subset of patients will manifest recurrent meningioma. Systemic therapy is recommended only when further surgery and radiotherapy are not possible. No prospective study with a high level of evidence is available to inform as to recommendations regarding systemic therapy.

AREAS COVERED

We aim to summarize systemic therapies for recurrent meningioma. Expert commentary: Hydroxurea, temozolomide, irinotecan, the combination of cyclophosphamide/adriamycine/vincristine, interferon-alpha, somatostatin analogs, mifepristone, megestrol acetate, imatinib, erlotinib and gefitinib are considered as having limited efficacy. Potential activity of VEGF (vascular endothelial growth factor) inhibitors such as sunitinib, valatinib, and bevacizumab is suggested in small non-controlled studies and requires validation in randomized trials. The identification of new prognostic markers such as TERT promoter mutations and potential new therapeutic targets, such as KLF4, AKT1, TRAF7, and SMO mutations hopefully facilitate this endeavor.

Somatostatin receptor-targeted radionuclide therapy for progressive meningioma: benefit linked to 68Ga-DOTATATE/-TOC uptake

BACKGROUND

The prognosis of patients with progressive meningioma after failure of surgery and radiotherapy is poor.

METHODS

We retrospectively evaluated the safety and efficacy of somatostatin-receptor (SSTR)-targeted radionuclide therapy (¹⁷⁷Lu-DOTATATE [n = 16], ⁹⁰Y-DOTATOC [n = 3], or both [n = 1]) in patients with progressive, treatment-refractory meningiomas (5 World Health Organization [WHO] grade I, 7 WHO grade II, 8 WHO grade III) and in part multifocal disease (17 of 20 patients).

RESULTS

SSTR radionuclide treatment (median of 3 treatment cycles, median administered dose/cycle 7400 MBq) led to a disease stabilization in 10 of 20 patients for a median time of 17 months. Stratification according to WHO grade showed a median progression-free survival (PFS) of 32.2 months for grade I tumors, 7.2 for grade II, and 2.1 for grade III. PFS at 6 months was 100% for grade I, 57% for grade II, and 0% for grade III. Median overall survival was 17.2 months in WHO grade III patients and not reached for WHO I and II at a median follow-up of 20 months. In the analysis of single meningioma lesions, maximal and mean standardized uptake values in pretherapeutic ⁶⁸Ga-DOTATOC/-TATE PET/CT were significantly higher in those lesions with radiographic stability after 6 months. In line with this, high expression of SSTR via immunohistochemistry was associated with PFS >6 months.

CONCLUSIONS

SSTR-targeted radionuclide treatment has activity in a subset of patients with meningioma. Expression of SSTR via immunohistochemistry or radionuclide uptake might serve as a predictive biomarker for outcome to facilitate individualized treatment optimization in patients with uni- and multifocal meningiomas.

Medical Management of Meningiomas: Current Status, Failed Treatments, and Promising Horizons

Meningiomas are benign tumors of the central nervous system, with low recurrence risk for World Health Organization (WHO) grade I lesions but a high risk for WHO grade II and III lesions. Current standard treatments include maximum safe surgical resection when indicated and radiation. Only three systemic therapies alpha-interferon, somatostatin receptor agonists, and vascular endothelial growth factor inhibitors are currently recommended by the National Comprehensive Cancer Network for treatment of recurrent meningioma. This paper aims to review medical approaches in the treatment of meningiomas.

Case-Based Review: meningioma

Meningioma is by far the most common primary intracranial tumor in adults. Treatment of meningioma is complex due to a tremendous amount of variability in tumor behavior. Many patients are incidentally found to have tumors that will remain asymptomatic throughout their lives. It is important to identify these patients so that they can be spared from potentially morbid interventions. On the other end of the spectrum, high-grade meningiomas can behave very aggressively. When treatment is necessary, surgical resection is the cornerstone of meningioma therapy. Studies spanning decades have demonstrated that extent of resection correlates with prognosis. Radiation therapy, either in the form of external beam radiation therapy or stereotactic radiosurgery, represents another important therapeutic tool that can be used in place of or as a supplement to surgery. There are no chemotherapeutic agents of proven efficacy against meningioma, and chemotherapy treatment is generally reserved for patients who have exhausted surgical and radiotherapy options. Ongoing and future studies will help to answer unresolved questions such as the optimum use of radiation in resected WHO grade II meningiomas and the efficacy of additional chemotherapy agents.

Intracranial Meningiomas: A 30-Year Experience and Literature Review

Intracranial meningiomas are tumors arising from the covering cells of the arachnoid layer of the dura mater or from the intraventricular choroid plexus. While mostly benign tumors, they still represent a major challenge to neurosurgeons and other medical disciplines involved in their diagnostic and therapeutic management. Although this review intends to give some state-of-the-art information from the literature, it is mainly based on personal experiences since more than 30 years caring for more than 1500 meningioma patients and point to a few new strategies to further improve on patient outcome.Diagnostics are based on magnetic resonance imaging which shows the relationship between tumor and surrounding intracranial structures, particularly the brain but also the vasculature and to some extent the cranial nerves. Furthermore, it may suggest the grading of the tumor and is very helpful in the postoperative diagnosis of complications and later follow-up course.Surgery still is the main treatment with the aim to completely remove the tumor; also in cases of recurrence, other additional options include radiotherapy and radiosurgery for incompletely removed or recurrent meningiomas. Postoperative chemotherapy has not been shown to provide substantial benefit to the patient especially in highly malignant meningiomas.All therapy options should be intended to provide the patient with the best possible functional outcome. Patients' perspective is not always equivalent to surgeons' perspectives. Neuropsychological evaluation and additional guidance of patients harboring meningiomas have proven to be important in modern neurosurgical intracranial tumor treatment. Their help beyond neurosurgical care facilitates the patients to lead an independent postoperative life.

Hydroxyurea with or without imatinib in the treatment of recurrent or progressive meningiomas: a randomized phase II trial by Gruppo Italiano Cooperativo di Neuro-Oncologia (GICNO)

PURPOSE

Hydroxyurea (HU) is among the most widely used salvage therapies in progressive meningiomas. Platelet-derived growth factor receptors are expressed in virtually all meningiomas. Imatinib sensitizes transformed cells to the cytotoxic effects of chemotherapeutic agents that interfere with DNA metabolism. The combination of HU with imatinib yielded intriguing results in recurrent malignant glioma. The current trial addressed the activity of this association against meningioma.

METHODS

Patients with recurrent or progressive WHO grade I-III meningioma, without therapeutic indication for surgery, radiotherapy, or stereotactic radiosurgery, aged 18-75 years, ECOG performance status 0-2, and not on enzyme-inducing anti-epileptic drugs were randomized to receive HU 500 mg BID ± imatinib 400 mg QD until progression, unacceptable toxicity, or patient's refusal. The primary endpoint was progression-free survival rate at 9 months (PFS-9).

RESULTS

Between September 2009 and February 2012, 15 patients were randomized to receive HU + imatinib (N = 7; Arm A) or HU alone (N = 8; Arm B). Afterward the trial was prematurely closed due to slow enrollment rate. PFS-9 (A/B) was 0/75%, and median PFS was 4/19.5 months. Median and 2-year overall survival (A/B) rates were: 6/27.5 months; 28.5/75%, respectively. Main G3-4 toxicities were: G3 neutropenia in 1/0, G4 headache in 1/1, and G3 vomiting in 1/0.

CONCLUSION

The conduction of a study in recurrent or progressive meningioma remains a challenge. Given the limited number of patients enrolled, no firm conclusions can be drawn about the combination of imatinib and HU. The optimal systemic therapy for meningioma failing surgery and radiation has yet to be identified.

Double-Blind Phase III Randomized Trial of the Antiprogestin Agent Mifepristone in the Treatment of Unresectable Meningioma: SWOG S9005

PURPOSE

Progesterone receptors are expressed in approximately 70% of meningiomas. Mifepristone is an oral antiprogestational agent reported to have modest activity in a phase II study. This multicenter, prospective, randomized, placebo-controlled phase III trial conducted by SWOG was planned to define the role of mifepristone in the treatment of unresectable meningioma.

PATIENTS AND METHODS

Eligible patients were randomly assigned to receive either mifepristone or placebo for 2 years unless disease progressed. Patients who were stable or responding to protocol therapy after 2 years had the option to continue with the same blinded therapy. Serial follow-up allowed assessment of efficacy and toxicity. Time to treatment failure and overall survival were ascertained for all randomly assigned patients. On progression, patients receiving placebo could cross over and receive active drug.

RESULTS

Among 164 eligible patients, 80 were randomly assigned to mifepristone and 84 to placebo. Twenty-four patients (30%) were able to complete 2 years of mifepristone without disease progression, adverse effects, or other reasons for discontinuation. Twenty-eight patients (33%) in the placebo arm completed the 2-year study. There was no statistical difference between the arms in terms of failure-free or overall survival.

CONCLUSION

Long-term administration of mifepristone was well tolerated but had no impact on patients with unresectable meningioma.

Medical management of meningiomas

The efficacy of surgery and radiation has been well validated in the treatment of meningiomas, with efficacy depending on tumor pathology, size, symptomatology and rate of progression. The role of medical therapy has the least amount of data but is being increasingly investigated for tumors that are inoperable or those tumors that recur and/or progress despite standard therapy. In this review, current data on the use of chemotherapeutic agents in the management of meningiomas will be reviewed, including cytotoxic, biologic, targeted molecular and hormonal agents.

An evidence-based treatment algorithm for the management of WHO Grade II and III meningiomas

The management of WHO Grade II “atypical” meningiomas (AMs) and Grade III “malignant” meningiomas (MMs) remains controversial and under-investigated in prospective studies. The roles of surgery, radiation therapy, radiosurgery, and chemotherapy have been incompletely delineated. This has left physicians to decipher how they should treat patients on a case-by-case basis. In this study, the authors review the English-language literature on the management and clinical outcomes associated with AMs and MMs diagnosed using the WHO 2000/2007 grading criteria. Twenty-two studies for AMs and 7 studies for MMs were examined in detail. The authors examined clinical decision points using the literature and concepts from evidence-based medicine. Acknowledging the retrospective nature of the studies concerning AM and MM, the authors did find evidence for the following clinical strategies: 1) maximal safe resection of AM and MM; 2) active surveillance after gross-total resection of AM; 3) adjuvant radiation therapy after subtotal resection of AM, especially in the absence of putative radioresistant features; and 4) adjuvant radiation therapy after resection of MM.

Imatinib mesylate plus hydroxyurea chemotherapy for cerebellar meningioma in a Belgian Malinois dog

An 8-year-old intact male Belgian Malinois, weighing 37.2 kg, was referred for evaluation due to right side facial paresis, ataxia and a 2-month history of decreased cognitive ability. Physical and neurological examinations revealed mild depression, left-sided head tilt, right-sided facial paresis and ataxia. A well-demarcated, broad-based cerebellar mass and hyperostosis were found on CT imaging of the brain. Based on these CT findings, a cerebellar meningioma was strongly suspected. Hydroxyurea and prednisolone were administered; after 4 weeks, there was reduction in mass size as compared to initial CT results. However, the mass size was found to have grown 6 weeks after hydroxyurea treatment. We then prescribed a combination of imatinib mesylate and hydroxyurea. Two weeks following combination treatment, the mass size had reduced significantly. The mass continuously decreased in size until the patient died during anesthesia. Cerebellar transitional meningioma was confirmed by histopathologic examination. To the author's knowledge, this is the first reported case of imatinib mesylate plus hydroxyurea therapy for the treatment of meningioma in veterinary medicine.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Re-evaluation of cytostatic therapies for meningiomas in vitro

PURPOSE

The purpose was to re-evaluate in cell culture models the therapeutic usefulness of some discussed chemotherapies or targeted therapies for meningiomas with a special emphasis on the role of the neurofibromatosis type 2 (NF2) tumor suppressor, which had been neglected so far. In addition, the study intended to evaluate a potential benefit from a treatment with drugs which are well established in other fields of medicine and have been linked recently with tumor disease by epidemiological studies.

METHODS

Meningioma cell lines corresponding to various subtypes and pairs of syngenic meningioma cell lines with or without shRNA-induced NF2 knockdown were analyzed for their dose-dependent response to the drugs in microtiter tetrazolium assays, BrdU assays and for selected cases in ELISAs measuring nucleosome liberation to specifically separate cell death from pure inhibition of cell proliferation.

RESULTS

We confirmed a moderate efficacy of hydroxyurea (HU) in clinically relevant concentrations. Under appropriate dosing, we neither detected major responses to the alkylating compound temozolomide nor to various drugs targeting membrane receptors or enzymes (tamoxifen, erlotinib, mifepristone, losartan, metformin and verapamil). Only concentrations far beyond achievable serum levels generated significant effects with the exception of losartan, which showed no effects at all. Chemosensitivity varied markedly among meningioma cell lines. Importantly, cells with NF2 loss exhibited a significantly higher induction of cell death by HU.

CONCLUSIONS

Alternative chemotherapeutic or targeted approaches besides HU have still to be evaluated in further studies, and the role of NF2 must be taken into account.

High-grade meningiomas: new avenues for drug treatment?

PURPOSE OF REVIEW

For standard first-line treatment of high-grade meningiomas, surgical resection and radiotherapy are regarded as standard of care. In the recurrent setting after exhaustion of all local treatment options, no effective therapies are known and several drugs have failed to show efficacy, but novel compounds may offer hope for better disease control.

RECENT FINDINGS

Upregulation of proangiogenic molecules and dysregulation of some signaling pathways such as the platelet-derived growth factor and mammalian target of rapamycin are recurrently found in high-grade meningiomas. Furthermore, in-vitro studies and single patient experience indicate that trabectedin may be an effective therapy in this tumor type. Unfortunately, so far there is a lack of conclusive clinical trials to draw definite conclusions of efficacy of these approaches.

SUMMARY

There remains a significant unmet need for defining the role of medical therapy in recurrent high-grade meningioma, and more basic research and multicentric well designed trials are needed in this rare and devastating tumor type. Potentially promising novel therapeutics include antiangiogenic drugs, molecular inhibitors of signaling cascades, immunotherapeutics or trabectedin. However, more basic research is required to identify more promising drug targets.

VIDEO ABSTRACT AVAILABLE

See the Video Supplementary Digital Content 1 (http://links.lww.com/CONR/A22).

Historical benchmarks for medical therapy trials in surgery- and radiation-refractory meningioma: a RANO review

BACKGROUND

The outcomes of patients with surgery- and radiation-refractory meningiomas treated with medical therapies are poorly defined. Published reports are limited by small patient numbers, selection bias, inclusion of mixed histologic grades and stages of illness, and World Health Organization (WHO) criteria changes. This analysis seeks to define outcome benchmarks for future clinical trial design.

METHODS

A PubMed literature search was performed for all English language publications on medical therapy for meningioma. Reports were tabulated and analyzed for number of patients, histologic grade, prior therapy, overall survival, progression-free survival (PFS), and radiographic response.

RESULTS

Forty-seven publications were identified and divided by histology and prior therapies, including only those that treated patients who were surgery and radiation refractory for further analysis. This included a variety of agents (hydroxyurea, temozolomide, irinotecan, interferon-α, mifepristone, octreotide analogues, megestrol acetate, bevacizumab, imatinib, erlotinib, and gefitinib) from retrospective, pilot, and phase II studies, exploratory arms of other studies, and a single phase III study. The only outcome extractable from all studies was the PFS 6-month rate, and a weighted average was calculated separately for WHO grade I meningioma and combined WHO grade II/III meningioma. For WHO I meningioma, the weighted average PFS-6 was 29% (95% confidence interval [CI]: 20.3%-37.7%). For WHO II/III meningioma, the weighted average PFS-6 was 26% (95% CI: 19.3%-32.7%).

CONCLUSIONS

This comprehensive review confirms the poor outcomes of medical therapy for surgery- and radiation-refractory meningioma. We recommend the above PFS-6 benchmarks for future trial design.

A case of recurrent anaplastic meningioma of the skull base with radiologic response to hydroxyurea

Anaplastic meningiomas are rare and aggressive tumors with a high propensity for local recurrence. Surgical resection and postoperative radiotherapy are the standard of care for primary disease and local recurrences. Refractory disease is managed with chemotherapy with limited success. A highly efficacious, well-tolerated chemotherapeutic agent has yet to be found for this disease entity. Hydroxyurea is currently receiving renewed attention because of its efficacy in inducing apoptosis of meningioma cells in vitro and its favorable side-effect profile. Thus far, in humans, this agent has only induced stable disease.

We describe the first patient showing a near complete/partial clinical and radiological regression after 5 months of 25 mg/kg of hydroxyurea once daily, given within 1 month after stereotactic fractionated reirradiation of a previously irradiated and operated anaplastic meningioma of the skull base. Magnetic resonance imaging showed a significant and sustained response with tumor shrinkage and cavitation.

A phase II trial of PTK787/ZK 222584 in recurrent or progressive radiation and surgery refractory meningiomas

When surgery and radiation are no longer treatment options, salvage systemic therapy has been used for recurrent meningiomas with little compelling evidence to suggest effectiveness. Patients with surgery and radiation refractory recurrent meningiomas were treated with the oral multifunctional tyrosine kinase inhibitor PTK787/ZK 222584 (PTK787) at a dose of 500 mg twice a day. Each treatment cycle was 4 weeks with MRI done every 8 weeks. Twenty-five patients (14 men; 11 women) with a median age of 59 years and KPS of 80 were treated. Meningioma WHO Grade was I in 2 patients, II in 14 patients and III in 8 patients; 1 patient had a hemangiopericytoma. All patients had prior surgery, external beam radiation therapy or radiosurgery and 11 patients prior systemic chemotherapy. Median number of cycles of PTK 787 administered was 4 (range <1-22). Best response in the 22 evaluable patients was stable disease in 15 (68.2 %). Predominant PTK787 related toxicities included fatigue (60 %), hypertension (24 %) and elevated transaminases (24 %). Grade II patients had a progression free survival (PFS)-6 of 64.3 %, a median PFS of 6.5 months and an overall survival (OS) of 26.0 months; grade III patients had a PFS-6 of 37.5 %, median PFS of 3.6 months and OS 23 months. PTK787 was modestly toxic at the dose of 500 mg administered twice per day. Activity as determined by PFS-6 suggests that targeting PDGF/VEGF pathway warrants further investigation.