Correlation Between Aspirin Intake and Reduced Growth of Human Vestibular Schwannoma: Volumetric Analysis

Losartan May Not Prevent Vestibular Schwannoma Growth or Related Hearing Loss During Observation

OBJECTIVE

To evaluate the impact of losartan on vestibular schwannoma (VS) growth and related hearing loss during observation.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Sporadic VS patients undergoing initial observation with at least two magnetic resonance imaging and audiologic examinations.

INTERVENTION

Losartan.

MAIN OUTCOME MEASURES

Endpoints included VS growth, quantitative audiologic changes, survival free of tumor growth, and survival free of nonserviceable hearing. Patient characteristics and endpoints were compared by losartan use.

RESULTS

Seventy-nine patients were included, of which 33% were taking losartan. Tumor growth was observed in 50% of patients in the losartan group and 36% in the non-losartan group (p = 0.329). Survival analysis failed to show a significant difference in the hazard rate of VS growth between groups (hazard ratio, 1.38; 95% confidence interval, 0.70-2.70; p = 0.346). Throughout observation, mean decreases in normalized pure-tone average were 5.5 and 9.3 dB in the losartan and non-losartan groups, respectively (p = 0.908). Mean decreases in normalized word recognition score were 11.0 and 16.6% in the losartan and non-losartan groups, respectively (p = 0.757). Nonserviceable hearing developed in 19% of patients in the losartan group and 28% in the non-losartan group (p = 0.734). Survival analysis did not demonstrate a significant difference in the hazard rate of developing nonserviceable hearing between groups (hazard ratio, 1.71; 95% confidence interval, 0.56-5.21; p = 0.337).

CONCLUSIONS

Losartan use may not reduce the risk of VS growth or hearing loss during observation. A randomized trial would be ideal to further identify the true effect on growth and hearing.

Gene Therapy for Neurofibromatosis Type 2-Related Schwannomatosis: Recent Progress, Challenges, and Future Directions

Neurofibromatosis type 2 (NF2)-related schwannomatosis is a rare autosomal dominant monogenic disorder caused by mutations in the NF2 gene. The hallmarks of NF2-related schwannomatosis are bilateral vestibular schwannomas (VS). The current treatment options for NF2-related schwannomatosis, such as observation with serial imaging, surgery, radiotherapy, and pharmacotherapies, have shown limited effectiveness and serious complications. Therefore, there is a critical demand for novel effective treatments. Gene therapy, which has made significant advancements in treating genetic diseases, holds promise for the treatment of this disease. This review covers the genetic pathogenesis of NF2-related schwannomatosis, the latest progress in gene therapy strategies, current challenges, and future directions of gene therapy for NF2-related schwannomatosis.

Tumors of the nervous system and hearing loss: Beyond vestibular schwannomas

Hearing loss is a common side effect of many tumor treatments. However, hearing loss can also occur as a direct result of certain tumors of the nervous system, the most common of which are the vestibular schwannomas (VS). These tumors arise from Schwann cells of the vestibulocochlear nerve and their main cause is the loss of function of NF2, with 95 % of cases being sporadic and 5 % being part of the rare neurofibromatosis type 2 (NF2)-related Schwannomatosis. Genetic variations in NF2 do not fully explain the clinical heterogeneity of VS, and interactions between Schwann cells and their microenvironment appear to be critical for tumor development. Preclinical in vitro and in vivo models of VS are needed to develop prognostic biomarkers and targeted therapies. In addition to VS, other tumors can affect hearing. Meningiomas and other masses in the cerebellopontine angle can compress the vestibulocochlear nerve due to their anatomic proximity. Gliomas can disrupt several neurological functions, including hearing; in fact, glioblastoma multiforme, the most aggressive subtype, may exhibit early symptoms of auditory alterations. Besides, treatments for high-grade tumors, including chemotherapy or radiotherapy, as well as incomplete resections, can induce long-term auditory dysfunction. Because hearing loss can have an irreversible and dramatic impact on quality of life, it should be considered in the clinical management plan of patients with tumors, and monitored throughout the course of the disease.

Single-cell multi-omic analysis of the vestibular schwannoma ecosystem uncovers a nerve injury-like state

Vestibular schwannomas (VS) are benign tumors that lead to significant neurologic and otologic morbidity. How VS heterogeneity and the tumor microenvironment (TME) contribute to VS pathogenesis remains poorly understood. In this study, we perform scRNA-seq on 15 VS, with paired scATAC-seq (n = 6) and exome sequencing (n = 12). We identify diverse Schwann cell (SC), stromal, and immune populations in the VS TME and find that repair-like and MHC-II antigen-presenting SCs are associated with myeloid cell infiltrate, implicating a nerve injury-like process. Deconvolution analysis of RNA-expression data from 175 tumors reveals Injury-like tumors are associated with larger tumor size, and scATAC-seq identifies transcription factors associated with nerve repair SCs from Injury-like tumors. Ligand-receptor analysis and in vitro experiments suggest that Injury-like VS-SCs recruit myeloid cells via CSF1 signaling. Our study indicates that Injury-like SCs may cause tumor growth via myeloid cell recruitment and identifies molecular pathways that may be therapeutically targeted.

Identification of immune-related candidate biomarkers in plasma of patients with sporadic vestibular schwannoma

Vestibular schwannoma (VS) is an intracranial tumor arising from neoplastic Schwann cells and typically presenting with hearing loss. The traditional belief that hearing deficit is caused by physical expansion of the VS, compressing the auditory nerve, does not explain the common clinical finding that patients with small tumors can have profound hearing loss, suggesting that tumor-secreted factors could influence hearing ability in VS patients. We conducted profiling of patients' plasma for 66 immune-related factors in patients with sporadic VS (N > 170) and identified and validated candidate biomarkers associated with tumor size (S100B) and hearing (MCP-3). We further identified a nine-biomarker panel (TNR-R2, MIF, CD30, MCP-3, IL-2R, BLC, TWEAK, eotaxin, and S100B) with outstanding discriminatory ability for VS. These findings revealed possible therapeutic targets for VS, providing a unique diagnostic tool that may predict hearing change and tumor growth in VS patients, and may inform the timing of tumor resection to preserve hearing.

The genetic landscape and possible therapeutics of neurofibromatosis type 2

Neurofibromatosis type 2 (NF2) is a genetic condition marked by the development of multiple benign tumors in the nervous system. The most common tumors associated with NF2 are bilateral vestibular schwannoma, meningioma, and ependymoma. The clinical manifestations of NF2 depend on the site of involvement. Vestibular schwannoma can present with hearing loss, dizziness, and tinnitus, while spinal tumor leads to debilitating pain, muscle weakness, or paresthesias. Clinical diagnosis of NF2 is based on the Manchester criteria, which have been updated in the last decade. NF2 is caused by loss-of-function mutations in the NF2 gene on chromosome 22, leading the merlin protein to malfunction. Over half of NF2 patients have de novo mutations, and half of this group are mosaic. NF2 can be managed by surgery, stereotactic radiosurgery, monoclonal antibody bevacizumab, and close observation. However, the nature of multiple tumors and the necessity of multiple surgeries over the lifetime, inoperable tumors like meningiomatosis with infiltration of the sinus or in the area of the lower cranial nerves, the complications caused by the operation, the malignancies induced by radiotherapy, and inefficiency of cytotoxic chemotherapy due to the benign nature of NF-related tumors have led a march toward exploring targeted therapies. Recent advances in genetics and molecular biology have allowed identifying and targeting of underlying pathways in the pathogenesis of NF2. In this review, we explain the clinicopathological characteristics of NF2, its genetic and molecular background, and the current knowledge and challenges of implementing genetics to develop efficient therapies.

Targeted Therapies in the Treatment of Vestibular Schwannomas: Current State and New Horizons

Vestibular schwannomas continue to cause hearing loss, facial nerve paralysis, imbalance, and tinnitus. These symptoms are compounded by germline neurofibromatosis type 2 (NF2) gene loss and multiple intracranial and spinal cord tumors associated with NF2-related schwannomatosis. The current treatments of observation, microsurgical resection, or stereotactic radiation may prevent catastrophic brainstem compression but are all associated with the loss of cranial nerve function, particularly hearing loss. Novel targeted treatment options to stop tumor progression include small molecule inhibitors, immunotherapy, anti-inflammatory drugs, radio-sensitizing and sclerosing agents, and gene therapy.

Identification of Immune-Related Candidate Biomarkers in Plasma of Patients with Sporadic Vestibular Schwannoma: Candidate Plasma Biomarkers in Vestibular Schwannoma

Vestibular schwannoma (VS) is intracranial tumor arising from neoplastic Schwann cells, causing hearing loss in about 95% of patients. The traditional belief that hearing deficit is caused by physical expansion of the VS, compressing the auditory nerve, does not explain the common clinical finding that patients with small tumors can have profound hearing loss, suggesting that tumor-secreted factors could influence hearing ability in VS patients. Here, we conducted profiling of patients' plasma for 67 immune-related factors on a large cohort of VS patients (N>120) and identified candidate biomarkers associated with tumor growth (IL-16 and S100B) and hearing (MDC). We identified the 7-biomarker panel composed of MCP-3, BLC, S100B, FGF-2, MMP-14, eotaxin, and TWEAK that showed outstanding discriminatory ability for VS. These findings revealed possible therapeutic targets for VS-induced hearing loss and provided a unique diagnostic tool that may predict hearing change and tumor growth in VS patients and may help inform the ideal timing of tumor resection to preserve hearing.

Tumor Biology and Microenvironment of Vestibular Schwannoma-Relation to Tumor Growth and Hearing Loss

Vestibular schwannoma is the most common benign neoplasm of the cerebellopontine angle. It arises from Schwann cells of the vestibular nerve. The first symptoms of vestibular schwannoma include hearing loss, tinnitus, and vestibular symptoms. In the event of further growth, cerebellar and brainstem symptoms, along with palsy of the adjacent cranial nerves, may be present. Although hearing impairment is present in 95% of patients diagnosed with vestibular schwannoma, most tumors do not progress in size or have low growth rates. However, the clinical picture has unpredictable dynamics, and there are currently no reliable predictors of the tumor's behavior. The etiology of the hearing loss in patients with vestibular schwannoma is unclear. Given the presence of hearing loss in patients with non-growing tumors, a purely mechanistic approach is insufficient. A possible explanation for this may be that the function of the auditory system may be affected by the paracrine activity of the tumor. Moreover, initiation of the development and growth progression of vestibular schwannomas is not yet clearly understood. Biallelic loss of the NF2 gene does not explain the occurrence in all patients; therefore, detection of gene expression abnormalities in cases of progressive growth is required. As in other areas of cancer research, the tumor microenvironment is coming to the forefront, also in vestibular schwannomas. In the paradigm of the tumor microenvironment, the stroma of the tumor actively influences the tumor's behavior. However, research in the area of vestibular schwannomas is at an early stage. Thus, knowledge of the molecular mechanisms of tumorigenesis and interactions between cells present within the tumor is crucial for the diagnosis, prediction of tumor behavior, and targeted therapeutic interventions. In this review, we provide an overview of the current knowledge in the field of molecular biology and tumor microenvironment of vestibular schwannomas, as well as their relationship to tumor growth and hearing loss.

Vestibular Schwannoma Volume and Tumor Growth Correlates with Macrophage Marker Expression

Simple Summary

The variable growth behavior of vestibular schwannomas (VS) makes therapy decisions very difficult. These benign tumors, which originate from the eighth cranial nerve, partly show a very slow growth rate over many years. Nevertheless, VS can lead to severe symptoms such as hearing loss and dizziness within a short time due to their increase in size. Despite numerous preliminary studies, no apparent influencing factor on size progression could be found so far. In our study, we consider the influence of growth factors and macrophage markers on the volume and growth rate of VS. While growth factors show no effect on tumor growth, higher expression of macrophage markers indicates an infiltration of macrophages. They may thus enhance the growth of VS and therefore represent a potential therapeutic target.

Abstract

Vestibular schwannoma is the most common benign tumor of the cerebellopontine angle and originates from Schwann cells surrounding the vestibulocochlear nerve. Since the size of the VS varies widely, affected patients suffer from symptoms of varying severity. It is often difficult to determine the optimal time for therapy, due to the unpredictability of the growth rate. Despite many investigations on influencing factors, no mechanism responsible for the increase in the growth rate of certain VS has been identified so far. Therefore, the present study investigates the influence of the seven markers: Ki-67, cyclooxygenase 2 (COX2), vascular endothelial growth factor (VEGF), macrophage colony-stimulating factor (M-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), CD163, and CD68 on tumor progression and tumor size in a cohort of 173 VS. The markers were determined by quantitative PCR and correlated with tumor volume and VS growth rate. The analysis showed a significantly negative correlation of the Ki-67, COX2, and VEGF on tumor volume. Moreover, with a higher volume of VS, the expression of the macrophage markers CD68, CD163, and GM-CSF increased significantly. Our results suggest that the increase in VS size is not primarily due to Schwann cell growth but to an infiltration of macrophages. This may have an impact on non-invasive therapy to preserve the hearing function of affected patients.

Clinical Trials Targeting Neurofibromatoses-associated Tumors: A Systematic Review

Background

There is a paucity of literature that comprehensively analyzes previous and current clinical trials targeting neurofibromatoses-related tumors. This article aims to provide readers with drug development efforts targeting these tumors by analyzing translational and clinical findings.

Methods

This systematic review was written according to the PRISMA guidelines. Inclusion criteria were clinical trials involving patients with neurofibromatosis type 1, type 2, or schwannomatosis that were treated with therapies targeting neurofibromatoses-associated tumors and that were registered on clinicaltrials.gov. In addition, a search was performed in PubMed, Web of Science, Google Scholar, and Embase European for articles fully describing these clinical trials.

Results

A total of 265 clinical trials were registered and screened for eligibility. Ninety-two were included in this systematic review involving approximately 4636 participants. The number of therapies analyzed was more than 50. Drugs under investigation mainly act on the MAPK/ERK and PI3K/AKT/mTOR pathways, tumor microenvironment, or aberrantly over-expressed cell surface receptors. Selumetinib was the most effective medication for treating a neurofibromatosis type 1-associated tumor with approximately 68%–71% partial response for inoperable or progressive plexiform neurofibromas in children 2 years of age and older and bevacizumab for a neurofibromatosis type 2-related tumor with approximately 36%–41% partial response for vestibular schwannomas in patients 12 years of age and older.

Conclusions

This systematic review presents the results of previous clinical investigations and those under development for neurofibromatoses-associated tumors. Clinicians may use this information to strategize patients to appropriate clinical trials.

Targeted Therapies for the Neurofibromatoses

Over the past several years, management of the tumors associated with the neurofibromatoses has been recognized to often require approaches that are distinct from their spontaneous counterparts. Focus has shifted to therapy aimed at minimizing symptoms given the risks of persistent, multiple tumors and new tumor growth. In this review, we will highlight the translation of preclinical data to therapeutic trials for patients with neurofibromatosis, particularly neurofibromatosis type 1 and neurofibromatosis type 2. Successful inhibition of MEK for patients with neurofibromatosis type 1 and progressive optic pathway gliomas or plexiform neurofibromas has been a significant advancement in patient care. Similar success for the malignant NF1 tumors, such as high-grade gliomas and malignant peripheral nerve sheath tumors, has not yet been achieved; nor has significant progress been made for patients with either neurofibromatosis type 2 or schwannomatosis, although efforts are ongoing.

Potential Molecular Biomarkers of Vestibular Schwannoma Growth: Progress and Prospects

Vestibular schwannomas (VSs, also known as acoustic neuromas) are relatively rare benign brain tumors stem from the Schwann cells of the eighth cranial nerve. Tumor growth is the paramount factor for neurosurgeons to decide whether to choose aggressive treatment approach or careful follow-up with regular magnetic resonance imaging (MRI), as surgery and radiation can introduce significant trauma and affect neurological function, while tumor enlargement during long-term follow-up will compress the adjacent nerves and tissues, causing progressive hearing loss, tinnitus and vertigo. Recently, with the deepening research of VS biology, some proteins that regulate merlin conformation changes, inflammatory cytokines, miRNAs, tissue proteins and cerebrospinal fluid (CSF) components have been proposed to be closely related to tumor volume increase. In this review, we discuss advances in the study of biomarkers that associated with VS growth, providing a reference for exploring the growth course of VS and determining the optimal treatment strategy for each patient.

Comparison of the Signal Intensity of Vestibular Schwannoma Between Growing and Nongrowing Tumors

OBJECTIVES/HYPOTHESIS

To determine the relationship between signal intensity on gadolinium (Gd)-enhanced magnetic resonance images and growth of vestibular schwannomas (VSs).

STUDY DESIGN

Cross-sectional study.

METHODS

In this cross-sectional study, we retrospectively reviewed the data of 31 patients with VSs who underwent magnetic resonance imaging (MRI). The mean signal intensities within the regions of interest in the tumor, pons, and temporal muscles were measured on Gd-enhanced T1-weighted MRI. Relative intensity ratios were calculated as follows: T/N pons ratio (T/Np) is the tumor signal intensity/pons signal intensity and T/N muscle ratio (T/Nm) is the tumor signal intensity/temporal muscle signal intensity. Volume measurements were used to assess the tumor size. Growth rate was determined by assessing previous imaging studies. Growing VS was defined as a tumor with a growth rate >100 mm³ /year.

RESULTS

The mean (standard deviation) T/Np and T/Nm were 1.47 (0.27) and 1.50 (0.24), respectively, in nongrowing tumors and 1.78 (0.17) and 1.90 (0.12), respectively, in growing tumors. The T/Np and T/Nm differed significantly between the two groups (T/Np, P < .001; T/Nm, P < .001). Receiver operating characteristic curve analysis showed that cutoffs of 1.56 and 1.76 for T/Np (93.33% sensitivity, 75.00% specificity) and T/Nm (100.00% sensitivity, 93.75% specificity), respectively, could be used to diagnose a growth rate of >100 mm³ /year. The area under the curve was 0.85 (95% confidence interval, 0.70-1.00) for T/Np and 0.94 (0.82-1.00) for T/Nm.

CONCLUSION

Growing VSs show higher signal intensities on Gd-enhanced MRI. Thus, measuring the signal intensity of VS on Gd-enhanced MRI may aid in predicting VS growth.

LEVEL OF EVIDENCE

3 Laryngoscope, 2021.

Association of Metformin With Volumetric Tumor Growth of Sporadic Vestibular Schwannomas

OBJECTIVE

Recent research demonstrates a potential association between metformin use and reduced sporadic vestibular schwannoma (VS) growth in patients undergoing conservative observation. The current study was designed to elucidate the effect of metformin on tumor growth in sporadic VS using volumetric analyses.

STUDY DESIGN

Retrospective cohort.

SETTING

Tertiary referral center.

PATIENTS

Patients with sporadic VS who elected initial conservative treatment with at least two serial magnetic resonance imaging (MRI) scans were included.

INTERVENTIONS

Metformin use among patients with observed sporadic VS.

MAIN OUTCOME MEASURES

Tumor growth, defined as an increase in volume of at least 20% from the initial MRI.

RESULTS

A total of 361 patients were evaluated. Thirty-four patients (9%) had a diagnosis of diabetes at baseline. Nineteen patients (5%) were taking metformin at the time of the initial MRI. Metformin use was not significantly associated with a reduced risk of volumetric tumor growth in a univariable analysis in all patients undergoing observation for VS (hazard ratio [HR] 0.75; 95% confidence intervals [CI] 0.40-1.42; p = 0.38) or within the diabetic subset (HR 0.79; 95% CI 0.34-1.83; p = 0.58). Additionally, diabetes status, insulin dependence, hemoglobin A1c value, and metformin dose were not significantly associated with volumetric tumor growth.

CONCLUSION

Despite promising initial results in several previous studies, our data suggest that metformin use does not significantly reduce the risk of volumetric tumor growth in sporadic VS.

The natural history of vestibular schwannoma growth-prospective 40-year data from an unselected national cohort

BACKGROUND

Optimal management of vestibular schwannoma (VS) is still debated and thus international consensus has not been achieved. Treatment options are observation, radiotherapy, and surgery. Knowledge on the natural history of tumor growth is essential for choice of treatment modality. The aim is to present intra-/extrameatal tumor growth and management data from a prospective, unselected national cohort of patients diagnosed with VS during the period 1976-2015.

METHODS

Since 1976, all data from patients diagnosed with sporadic VS in Denmark have been referred to our national treatment center, where they have been entered prospectively into the national database. Data on tumor localization, growth, and treatment were retrieved. Growth definition: >2 mm by linear measurement, in accordance with the Tokyo 2001 consensus-meeting recommendations.

RESULTS

3637 cases of VS were diagnosed, in which 1304 patients had surgery and 21 received radiotherapy post diagnosis. 2312 patients were observed with mean follow-up of 7.33 years. Of these, 434(19%; 102 intra-and 332 extrameatal tumors) changed to active treatment during the observation period due to tumor growth. 5 years after diagnosis, 21% of the intrameatal tumors exhibited growth during observation, whereas 37% of extrameatal tumors had grown, increasing to 25% intrameatal and 42% extrameatal after 10 years. Following growth, the intrameatal tumors were mostly observed further and the extrameatal mostly underwent surgery. Tumor growth occurred mainly within the first 5 years post diagnosis.

CONCLUSION

This natural history study documents the growth occurrence of both intra-and extrameatal VS during the first 12 years after diagnosis and should be used in patient counseling, management, and treatment decision making.

Efficacy of aspirin for sporadic vestibular schwannoma: a meta-analysis

BACKGROUND

Pharmacologic treatment of vestibular schwannomas (VSs) may increase the success of conservative management for small lesions, and offer an alternative to surgery and stereotactic radiotherapy in symptomatic cases in the high-risk population. Agents that have been studied include aspirin (ASA), but the results of the preliminary studies have been conflicting. In this study, we aimed to systematically review the evidence on the effect of ASA intake on tumor growth in patients with VSs.

METHODS

Pubmed, Cochrane, Scopus, Embase, ClinicalTrials.gov , and Web of Science were searched for studies comparing VS tumor growth in patients with aspirin intake and those without. Random-effect meta-analysis was used to evaluate the outcomes in terms of linear and/or volumetric tumor growth.

RESULTS

Four retrospective cohort studies were included in the meta-analysis. No significant difference was found in tumor growth between VS patients with aspirin intake and those without. This result held true for the analysis of linear tumor growth (OR 1.23; 95% CI 0.49, 3.10), volumetric tumor growth (OR 1.41; 95% CI 0.36, 5.59), and both combined (OR 1.02; 95% CI 0.56, 1.86).

CONCLUSIONS

Our meta-analysis suggests that there is insufficient evidence to recommend ASA therapy in patients with VSs. High-quality randomized controlled trials are warranted to determine the efficacy of this drug in reducing VS tumor growth.

COX2 expression is associated with preoperative tumor volume but not with volumetric tumor growth in vestibular schwannoma

OBJECTIVE

Vestibular schwannomas (VS) are benign slow growing tumors arising from the vestibular nerve. The role of cyclooxygenase 2 (COX2) in tumor development of growth has been addressed in a few studies with contradictory results and suggestions. We recently analyzed the immunohistochemical expression of COX2 in 1044 VS samples and described an association of higher COX2 expression with proliferation but found no influence by regular intake of acetylsalicylic acid. We now collected volumetric radiographic data of the preoperative tumor volume and growth to further test the role of COX2 in VS growth.

METHODS

Preoperative images of 898 primary sporadic vestibular schwannomas were assessed, and sufficient preoperative imaging was used for the volumetric measurement preoperative tumor volume (n = 747) and preoperative relative tumor growth (n = 171). Clinical parameters and results of the immunohistochemical expression of COX2 and MIB1 in resected tumor tissue samples were obtained from our prior study. ANOVA, CART-analysis and multivariate nominal logistic regression were used for statistical analysis.

RESULTS

Larger preoperative tumor volumes were observed with tumors of younger patients (p = 0.0288) and with higher COX2 expression scores (p < 0.0001). Higher MIB1 expression was associated with smaller tumors (p = 0.0149) but with increased radiographic tumor growth (p = 0.0003). Patients of older age had tumors with slower growth rates (p = 0.0311). In the multivariate analysis only MIB1 expression was an independent significant factor regarding tumor growth (p = 0.0002).

CONCLUSIONS

Higher expression of COX2 in schwannoma is associated with an increased preoperative tumor volume but not with radiographic tumor growth over time.

Gross-total versus near-total resection of large vestibular schwannomas. An institutional experience

OBJECTIVE

We will report our experience of the surgical treatment of large vestibular schwannomas (VSs).

PATIENTS, MATERIALS AND METHODS

We conducted a retrospective study of patients operated on for Koos grade IV VS between 2007 and 2015 at the Department of Neurosurgery, Emergency County Hospital, Târgu Mureş, Romania. We studied the general preoperatory clinical data, the preoperative and postoperative facial nerve status, preoperative hearing on the affected side, and any postoperative complications, including death.

RESULTS

Sixty-six cases were included in our study. The mean age was 52.95 years and 66.7% (n=44) of the sample were female. All patients had suffered from tinnitus and this had been followed by loss of serviceable hearing on the affected side in 89.4% (n=59) of cases. Preoperative facial palsy was found in 53% (n=35) of patients. The mean tumor size was 40.35 mm. Gross-total resection (GTR) was achieved in 24 (36.36%) cases, while near-total resection (NTR) was obtained in 42 (63.64%) cases. New-onset facial palsy or degradation of the preoperative facial deficit occurred in 12 (18.18%) cases, most of whom were patients with a GTR (n=9, 37.5%). This was statistically significant. There were no significant postoperative differences between the GTR and NTR groups. There was one death in the GTR group.

CONCLUSIONS

We conclude that near-total tumor removal provides good surgical results and better postsurgical quality of life for patients when compared to gross-total tumor resection. Therefore, this should be the end goal of the resection of large VSs.

New developments in neurofibromatosis type 2 and vestibular schwannoma

Neurofibromatosis type 2 (NF2) is a rare autosomal dominant disorder characterized by the development of multiple nervous system tumors due to mutation in the NF2 tumor suppressor gene. The hallmark feature of the NF2 syndrome is the development of bilateral vestibular schwannomas (VS). Although there is nearly 100% penetrance by 60 years of age, some patients suffer from a severe form of the disease and develop multiple tumors at an early age, while others are asymptomatic until later in life. Management options for VS include surgery, stereotactic radiation, and observation with serial imaging; however, currently, there are no FDA-approved pharmacotherapies for NF2 or VS. Recent advancements in the molecular biology underlying NF2 have led to a better understanding of the etiology and pathogenesis of VS. These novel signaling pathways may be used to identify targeted therapies for these tumors. This review discusses the clinical features and treatment options for sporadic- and NF2-associated VS, the diagnostic and screening criteria, completed and ongoing clinical trials, quality of life metrics, and opportunities for future research.

Beyond Antoni: A Surgeon's Guide to the Vestibular Schwannoma Microenvironment

Introduction Vestibular schwannomas (VS) are histologically benign tumors arising from cranial nerve VIII. Far from a homogenous proliferation of Schwann cells, mounting evidence has highlighted the complex nature of the inflammatory microenvironment in these tumors.

Methods A review of the literature pertaining to inflammation, inflammatory molecular pathways, and immune-related therapeutic targets in VS was performed. Relevant studies published up to June 2020 were identified based on a literature search in the PubMed and MEDLINE databases and the findings were synthesized into a concise narrative review of the topic.

Results The VS microenvironment is characterized by a dense infiltrate of inflammatory cells, particularly macrophages. Significantly higher levels of immune cell infiltration are observed in growing versus static tumors, and there is a demonstrable interplay between inflammation and angiogenesis in growing VS. While further mechanistic studies are required to ascertain the exact role of inflammation in angiogenesis, tumor growth, and Schwann cell control, we are beginning to understand the key molecular pathways driving this inflammatory microenvironment, and how these processes can be monitored and targeted in vivo.

Conclusion Observational research has revealed a complex and heterogeneous tumor microenvironment in VS. The functional landscape and roles of macrophages and other immune cells in the VS inflammatory infiltrate are, however, yet to be established. The antiangiogenic drug bevacizumab has shown the efficacy of targeted molecular therapies in VS and there is hope that agents targeting another major component of the VS microenvironment, inflammation, will also find a place in their future management.

MMP-14 (MT1-MMP) Is a Biomarker of Surgical Outcome and a Potential Mediator of Hearing Loss in Patients With Vestibular Schwannomas

Improved biomarkers are needed for vestibular schwannoma (VS), the most common tumor of the cerebellopontine angle, as existing clinical biomarkers have poor predictive value. Factors such as tumor size or growth rate do not shed light on the pathophysiology of associated sensorineural hearing loss (SNHL) and suffer from low specificity and sensitivity, whereas histological markers only sample a fraction of the tumor and are difficult to ascertain before tumor treatment or surgical intervention. Proteases play diverse and critical roles in tumorigenesis and could be leveraged as a new class of VS biomarkers. Using a combination of in silico, in vitro, and ex vivo approaches, we identified matrixmetalloprotease 14 (MMP-14; also known as MT1-MMP), from a panel of candidate proteases that were differentially expressed through the largest meta-analysis of human VS transcriptomes. The abundance and proteolytic activity of MMP-14 in the plasma and tumor secretions from VS patients correlated with clinical parameters and the degree of SNHL. Further, MMP-14 plasma levels correlated with surgical outcomes such as the extent of resection. Finally, the application of MMP-14 at physiologic concentrations to cochlear explant cultures led to damage to spiral ganglion neuronal fibers and synapses, thereby providing mechanistic insight into VS-associated SNHL. Taken together, MMP-14 represents a novel molecular biomarker that merits further validation in both diagnostic and prognostic applications for VS.

Association of Metformin With the Growth of Vestibular Schwannomas

Objective

To assess whether medication use, specifically statin, metformin, and aspirin, affects the growth of vestibular schwannomas (VSs).

Study Design

Retrospective case series.

Setting

Single tertiary care academic hospital.

Subjects and Methods

Patients were enrolled if they were diagnosed with sporadic VS and had at least 2 magnetic resonance imaging (MRI) studies at a minimum of 6 months apart prior to any intervention. Electronic medical records were reviewed for demographic and medication data. Tumor volumes on MRI studies were assessed via BrainLab iPlan. The primary endpoint was VS tumor growth, defined as a 20% increase in tumor volume, between consecutive MRI studies or between the first and last available MRI study. Predictors of volumetric growth, specifically statin, aspirin, or metformin use, were analyzed with t tests, chi-square test, univariate logistic regression, and multivariate logistic regression.

Results

A total of 387 patients met inclusion criteria, 53.5% of whom were women. For all patients, the mean age was 60.6 years (range, 18.2-89.2 years); the mean axial tumor diameter, 11.9 mm (range, 1.7-32.0 mm); and the mean tumor volume, 0.85 cm3 (range, 0.01-13.1 cm3). In review of the electronic medical record, 46 patients (11.9%) were taking metformin; 145 (37.5%), a statin; and 117 (30.2%), aspirin. Among patients taking metformin, 39.1% (18/46) exhibited volumetric growth, as opposed to 58.2% (198/340) of nonusers ( P = .014). Metformin (odds ratio, 0.497; P = .036) is significantly associated with reduced VS growth when controlling for aspirin, statin, and tumor size on multivariate logistic regression.

Conclusion

Metformin use is associated with reduced volumetric VS growth.

Vestibular Schwannoma: What We Know and Where We are Heading

Vestibular schwannoma (VS) is a Schwann cell-derived tumour arising from the vestibulocochlear nerve. Although benign, it represents a threat to intracranial structures due to mass effect and carries a small risk of malignant transformation. VS therefore represents an important healthcare burden. We review the literature regarding pathogenesis, risk factors, and diagnosis of VS. The current and future potential management strategies are also discussed. A narrative review of all relevant papers known to the authors was conducted. The majority of VS remain clinically stable and do not require interventional procedures. Nevertheless, various surgical techniques exist for removing VS, the most common of which are translabyrinthine and retrosigmoid approaches. Due to surgical risks such as hearing loss, facial nerve dysfunction, post-operative headache, and cerebrospinal fluid leakage, a "watch and rescan" approach is adopted for most patients. Radiotherapy is a useful alternative and has been shown to have a similar response for growth restriction. Due to the heterogeneous nature of VS, there is a lack of consensus regarding management of tumours that are too large for conservative management but too small to indicate surgery. Emerging biologic therapies, such as Bevacizumab, Everolimus, and Lapatinib, as well as anti-inflammatories like aspirin are promising potential treatments; however, long-term evidence of their efficacy is required. The knowledge base regarding VS continues to improve. With increased understanding of the pathogenesis of these tumors, we believe future work should focus on pharmacologic intervention. Biologic therapies aimed toward improved patient outcomes are particularly promising.

The inflammatory microenvironment in vestibular schwannoma

Vestibular schwannomas are tumors arising from the vestibulocochlear nerve at the cerebellopontine angle. Their proximity to eloquent brainstem structures means that the pathology itself and the treatment thereof can be associated with significant morbidity. The vast majority of these tumors are sporadic, with the remainder arising as a result of the genetic syndrome Neurofibromatosis Type 2 or, more rarely, LZTR1-related schwannomatosis. The natural history of these tumors is extremely variable, with some tumors not displaying any evidence of growth, others demonstrating early, persistent growth and a small number growing following an extended period of indolence. Emerging evidence now suggests that far from representing Schwann cell proliferation only, the tumor microenvironment is complex, with inflammation proposed to play a key role in their growth. In this review, we provide an overview of this new evidence, including the role played by immune cell infiltration, the underlying molecular pathways involved, and biomarkers for detecting this inflammation in vivo. Given the limitations of current treatments, there is a pressing need for novel therapies to aid in the management of this condition, and we conclude by proposing areas for future research that could lead to the development of therapies targeted toward inflammation in vestibular schwannoma.

Surgery of the lateral skull base: a 50-year endeavour

Disregarding the widely used division of skull base into anterior and lateral, since the skull base should be conceived as a single anatomic structure, it was to our convenience to group all those approaches that run from the antero-lateral, pure lateral and postero-lateral side of the skull base as “Surgery of the lateral skull base”. “50 years of endeavour” points to the great effort which has been made over the last decades, when more and more difficult surgeries were performed by reducing morbidity. The principle of lateral skull base surgery, “remove skull base bone to approach the base itself and the adjacent sites of the endo-esocranium”, was then combined with function preservation and with tailoring surgery to the pathology. The concept that histology dictates the extent of resection, balancing the intrinsic morbidity of each approach was the object of the first section of the present report. The main surgical approaches were described in the second section and were conceived not as a step-by-step description of technique, but as the highlighthening of the surgical principles. The third section was centered on open issues related to the tumor and its treatment. The topic of vestibular schwannoma was investigated with the current debate on observation, hearing preservation surgery, hearing rehabilitation, radiotherapy and the recent efforts to detect biological markers able to predict tumor growth. Jugular foramen paragangliomas were treated in the frame of radical or partial surgery, radiotherapy, partial “tailored” surgery and observation. Surgery on meningioma was debated from the point of view of the neurosurgeon and of the otologist. Endolymphatic sac tumors and malignant tumors of the external auditory canal were also treated, as well as chordomas, chondrosarcomas and petrous bone cholesteatomas. Finally, the fourth section focused on free-choice topics which were assigned to aknowledged experts. The aim of this work was attempting to report the state of the art of the lateral skull base surgery after 50 years of hard work and, above all, to raise questions on those issues which still need an answer, as to allow progress in knowledge through sharing of various experiences. At the end of the reading, if more doubts remain rather than certainties, the aim of this work will probably be achieved.

Epidemiology Of Vestibular Schwannomas - Prospective 40-Year Data From An Unselected National Cohort

Objective

Reports on the epidemiology of vestibular schwannoma (VS) indicate an increase in diagnosed cases, often based on selected materials over a limited period of time. This report presents prospective 40-year epidemiological data from an unselected national cohort of all patients diagnosed with a VS in Denmark since 1976.

Study-design

Data on gender, age, tumor localization and size registered during the period 1976–2015 were retrieved.

Results

3637 new cases of VS were diagnosed during the 40-year period. The annual number of diagnosed VS increased from 14 in 1976 to 193 in 2015. Mean extrameatal tumor size decreased from 26mm in 1976 to 13.4mm in 2015. Large and giant tumors were more frequent during the first decades, whereas predominantly smaller tumors were diagnosed during the recent years. Median age at diagnosis increased gradually from 49.2 years in 1976 to 60 years in 2015.

Conclusion

Over the past 40 years, the incidence rate of vestibular schwannomas has increased steadily from 3 VS/million/year to 34 VS/million/year, primarily due to easier access to improved diagnostics and the finding of more tumors in older people. Concurrently, the diagnostic tumor size has decreased from 26mm to 7mm, and the age at diagnosis has increased from 49 to 60 years.

Noncontrast vestibular schwannoma surveillance imaging including an MR cisternographic sequence: is there a need for postcontrast imaging?

OBJECTIVE

The purpose of this study was to evaluate the use of a noncontrast MRI protocol that includes a cisternographic sequence (CISS/FIESTA/3D DRIVE) compared to a protocol that includes a gadolinium-enhanced sequence in order to determine whether a noncontrast approach could be utilized to follow vestibular schwannomas.

METHODS

A total of 251 patients with vestibular schwannomas who underwent MRI of the temporal bones that included both cisternographic sequence and postcontrast T1 imaging between January 2000 and January 2016 for surveillance were included in this retrospective study. The size of the vestibular schwannomas was independently assessed on a noncontrast MR cisternographic sequence and compared to size measurements on a postcontrast sequence. The evaluation of intralesional cystic components (identified as T2 signal hyperintensity) and hemorrhagic components (identified with intrinsic T1 hyperintensity) on noncontrast MR sequences was compared to evaluation on postcontrast MR sequences to determine whether additional information could be derived from the postcontrast sequences. Additionally, any potentially clinically significant, incidentally detected findings on the postcontrast T1 sequences were documented and compared with the detection of these findings on the precontrast images.

RESULTS

No significant difference in vestibular schwannoma size was found when comparing measurements made on the images obtained with the MR cisternographic sequence and those made on images obtained with the postcontrast sequence (p = 0.99). Noncontrast MR images were better (detection rate of 87%) than postcontrast images for detection of cystic components. Noncontrast MR images were also better for identifying hemorrhagic components. No additional clinically relevant information regarding the tumors was identified on the postcontrast sequences.

CONCLUSIONS

Based on the results of this study, a noncontrast MR protocol that includes a cisternographic sequence would be sufficient for the accurate characterization of size and signal characteristics of vestibular schwannomas, obviating the need for gadolinium contrast administration for the routine surveillance of these lesions.

NLRP3 inflammasome activation in human vestibular schwannoma: Implications for tumor-induced hearing loss

Vestibular schwannoma (VS) is the fourth most common intracranial tumor, arising from neoplastic Schwann cells of the vestibular nerve and often causing debilitating sensorineural hearing loss (SNHL) and tinnitus. Previous research suggests that the abnormal upregulation of inflammatory pathways plays a highly significant, though infrequently described role in VS pathobiology, and that VS-associated SNHL is due not only to mechanical compression of the auditory nerve but also to differences in the intrinsic biology of these tumors. We hypothesize that patients who present with poor hearing associated with VS experience a more robust inflammatory response to this tumor than VS patients who present with good hearing. To investigate this hypothesis, we conducted a comprehensive pathway analysis using gene expression data from the largest meta-analysis of vestibular schwannoma microarray data, comprising 80 tumors and 16 healthy peripheral nerves. We identified the NLRP3 inflammasome as a novel target worthy of further exploration in VS research and validated this finding at the gene and protein expression level in human VS tissue using qRT-PCR and immunohistochemistry. To date, NLRP3 inflammasome activation has not been reported in VS, and this finding may represent a new and potentially significant therapeutic avenue. Notably, after analysis of 30 VSs, we observe that overexpression of key components of the NLRP3 inflammasome is preferentially associated with tumors that produce increased hearing loss in VS patients. Therefore, therapeutic development for VS should include considerations for minimizing NLRP3-associated inflammation to best preserve hearing.

COX2 expression is associated with proliferation and tumor extension in vestibular schwannoma but is not influenced by acetylsalicylic acid intake

Acetylsalicylic acid has been linked to a lower risk for different cancer types, presumably through its inhibitory effect on cyclooxygenase 2. This has also been investigated in vestibular schwannomas with promising results suggesting an antiproliferative effect and recently the intake has been recommended for vestibular schwannomas as a conservative treatment option. We constructed tissue microarrays from paraffin-embedded tissue samples of 1048 vestibular schwannomas and analyzed the expression of cyclooxygenase 2 and the proliferation marker MIB1 (Molecular Immunology Borstel) via immunohistochemistry together with clinical data (age, gender, tumor extension, prior radiotherapy, neurofibromatosis type 2, tumor recurrence, cyclooxygenase 2 responsive medication). Univariate analysis showed that cyclooxygenase 2 expression was increased with age, female gender, prior radiotherapy and larger tumor extension. MIB1 expression was also associated with higher cyclooxygenase 2 expression. Schwannomas of neurofibromatosis type 2 patients had lower cyclooxygenase 2 levels. Use of acetylsalicylic acid, non-steroidal anti-inflammatory drugs, glucocorticoids or other immunosuppressants did not show differences in cyclooxygenase 2 or MIB1 expression. Instead, cyclooxygenase 2 expression increases with tumor extension while MIB1 expression is not associated with tumor size. Overall, cyclooxygenase 2 expression is associated with proliferation but not influenced by regular intake of acetylsalicylic acid or other cyclooxygenase 2-responsive medications. Acetylsalicylic acid intake does not alter cyclooxygenase 2 expression and has no antiproliferative effect in vestibular.

Impact of Aspirin and Other NSAID Use on Volumetric and Linear Growth in Vestibular Schwannoma

Objectives

Conflicting research exists surrounding the utility of aspirin to prevent tumor growth in the medical management of vestibular schwannoma (VS). Recent studies demonstrated no association between aspirin and VS growth using linear tumor measurements. Given the heightened sensitivity of volumetric analyses to monitor tumor growth, the current study was conceived with the chief objective of assessing the association between aspirin or other nonsteroidal anti-inflammatory drug (NSAID) use and VS growth using volumetric analyses.

Study Design

Retrospective review.

Setting

Tertiary referral center.

Subjects and Methods

A total of 361 patients totaling 1601 volumetrically analyzed magnetic resonance imaging studies who underwent initial observation since January 1, 2003.

Results

In total, 123 (35%) patients took 81 mg aspirin daily, 23 (7%) took 325 mg aspirin daily, and 41 (11%) reported other NSAID use. Among those taking aspirin, 112 (72%) exhibited volumetric tumor growth during observation compared to 33 (80%) among other NSAID users and 137 (67%) among nonaspirin users. Patients taking aspirin or other NSAIDs were significantly older at time of diagnosis (median, 66 vs 56 years; P < .001). Neither aspirin use (hazard ratio [HR], 0.96; P = .73) nor other NSAID use (HR, 1.39; P = .081) was significantly associated with a reduced risk of volumetric tumor growth. These results were similar following age adjustment ( P = .81 and .087, respectively). When separating aspirin users by 81-mg or 325-mg dosing, neither group exhibited a reduced risk of growth ( P = .95 and .73, respectively).

Conclusion

Despite promising initial results, the preponderance of existing literature suggests that aspirin and other NSAID use does not prevent tumor growth in VS.

Natural History of Sporadic Vestibular Schwannoma: A Volumetric Study of Tumor Growth

Objective

(1) Assess 3-dimensional volumetric growth of untreated sporadic vestibular schwannomas (VSs) in a large cohort of patients treated with conservative observation. (2) Compare volumetric and conventional linear diameter measurements for detecting tumor growth.

Study Design

Case series with chart review.

Setting

Tertiary skull base referral center.

Subjects and Methods

Patients with sporadic VS who elected initial conservative treatment with at least 2 serial magnetic resonance imaging (MRI) scans were included. Tumor volume was determined with 3-dimensional segmentation of MRI sequences. The volumetric threshold for tumor growth was an increase ≥20% from baseline tumor volume. Tumor size based on linear diameter was assessed with the 1995 American Academy of Otolaryngology—Head and Neck Surgery Foundation guidelines for VS outcome reporting, with growth defined as an increase ≥2 mm.

Results

A total of 361 patients were included with a median radiologic follow-up of 4.1 years (interquartile range [IQR], 2.5-6.8). At diagnosis, 232 VSs (64%) were purely intracanalicular, and 129 (36%) extended into the cerebellopontine angle. The median baseline tumor volume was 0.161 cm3 (IQR, 0.054-0.418). Overall, 69% of tumors demonstrated volumetric growth at a median of 1.1 years (IQR, 0.6-2.1) after initial MRI. In contrast, based on linear measurement assessment, 48% of tumors demonstrated growth at a median of 1.8 years (IQR, 0.8-3.1) from first MRI scan. Disequilibrium, facial hypoesthesia, aural fullness, initial tumor size, and nonincidental diagnosis were associated with tumor growth.

Conclusion

Three-dimensional volumetric assessment of VS provides a more sensitive measure of tumor growth when compared with linear diameter assessment. Through volumetric analysis, the current study revealed that a significant proportion of VSs demonstrate growth during observation.

Long-term tumor control following stereotactic radiosurgery for jugular paraganglioma using 3D volumetric segmentation

OBJECTIVE

The morbidity of gross-total resection of jugular paraganglioma (JP) is often unacceptable due to the potential for irreversible lower cranial neuropathy. Stereotactic radiosurgery (SRS) has been used at the authors' institution since 1990 for the treatment of JP and other benign intracranial tumors. Conventional means of assessing tumor progression using linear measurements or elliptical approximations are imprecise due to the irregular shape and insinuating growth pattern of JP. The objective of this study was to assess long-term tumor control in these patients by using slice-by-slice 3D volumetric segmentation of serial MRI data.

METHODS

Radiographic data and clinical records were reviewed retrospectively at a single, tertiary-care academic referral center for patients treated from 1990 to 2017. Volumetric analyses by integration of consecutive tumor cross-sectional areas (tumor segmentation) of serial MRI data were performed. Tumor progression was defined as volumetric growth of 15% or greater over the imaging interval. Primary outcomes analyzed included survival free of radiographic and clinical progression. Secondary outcomes included new or worsened cranial neuropathy.

RESULTS

A total of 85 patients were treated with Gamma Knife radiosurgery (GKRS) for JP at the authors' institution over the last 27 years. Sixty patients had pretreatment and serial posttreatment contrast-enhanced MRI follow-up suitable for volumetric analysis. A total of 214 MR images were analyzed to segment tumor images in a slice-by-slice fashion to calculate integral tumor volume. The median follow-up duration was 66 months (range 7-202 months). At 5 years the tumor progression-free survival rate was 98%. Three tumors exhibited progression more than 10 years after GKRS. Estimated survival free of radiographic progression rates (95% confidence interval [CI]; n = number still at risk) at 5, 10, and 15 years following radiosurgery were 98% (95% CI 94%-100%; n = 34), 94% (95% CI 85%-100%; n = 16), and 74% (95% CI 56%-98%; n = 6), respectively. One patient with tumor progression required treatment intervention using external beam radiation therapy, constituting the only case of clinical progression. Two patients (3%) without preexisting lower cranial nerve dysfunction developed new ipsilateral vocal fold paralysis following radiosurgery.

CONCLUSIONS

SRS achieves excellent long-term tumor control for JP without a high risk for new or worsened cranial neuropathy when used in primary, combined modality, or recurrent settings. Long-term follow-up is critical due to the potential for late radiographic progression (i.e., more than 10 years after SRS). As none of the patients with late progression have required salvage therapy, the clinical implications of this degree of tumor growth have yet to be determined.

Vestibular Schwannoma Growth With Aspirin and Other Nonsteroidal Anti-inflammatory Drugs

OBJECTIVE

To investigate whether the use of aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) impact the growth of vestibular schwannoma (VS).

STUDY DESIGN

Retrospective case series.

SETTING

Single academic, tertiary care center.

PATIENTS

Patients with VS who underwent at least two magnetic resonance imaging (MRI) studies before intervention.

INTERVENTION(S)

Serial MRI studies.

MAIN OUTCOME MEASURE(S)

VS tumor growth, defined as more than or equal to 2 mm increase in the maximum tumor diameter between consecutive MRI studies, or between the first and last available study. Mean growth rate was also calculated, defined as the change in tumor size divided by length of follow-up.

RESULTS

A total of 564 VS patients met inclusion criteria, with 234 (41.2%) taking some type of NSAID. Aspirin use was not associated with VS tumor growth, presenting tumor diameter, or mean VS growth rate. Further, aspirin dosage did not impact growth outcomes or presenting tumor diameter. A total of 96 (17.0%) patients took an NSAID other than aspirin. Neither non-aspirin NSAID use nor degree of cyclooxygenase-2 (COX-2) selectivity, including aspirin, was significantly associated with VS tumor growth, presenting tumor diameter, or mean VS growth rate.

CONCLUSIONS

While previous studies have suggested a relationship between aspirin usage and VS growth, we found no significant association in our series of 564 observed VS. Furthermore, there was no apparent relationship between aspirin dosage, non-aspirin NSAID use, and COX-2 selectivity with VS growth, presenting tumor diameter at presentation, or mean VS growth rate.

Computational repositioning and preclinical validation of mifepristone for human vestibular schwannoma

The computational repositioning of existing drugs represents an appealing avenue for identifying effective compounds to treat diseases with no FDA-approved pharmacotherapies. Here we present the largest meta-analysis to date of differential gene expression in human vestibular schwannoma (VS), a debilitating intracranial tumor, and use these data to inform the first application of algorithm-based drug repositioning for this tumor class. We apply an open-source computational drug repositioning platform to gene expression data from 80 patient tumors and identify eight promising FDA-approved drugs with potential for repurposing in VS. Of these eight, mifepristone, a progesterone and glucocorticoid receptor antagonist, consistently and adversely affects the morphology, metabolic activity, and proliferation of primary human VS cells and HEI-193 human schwannoma cells. Mifepristone treatment reduces VS cell viability more significantly than cells derived from patient meningiomas, while healthy human Schwann cells remain unaffected. Our data recommend a Phase II clinical trial of mifepristone in VS.

Macrophage Density Predicts Facial Nerve Outcome and Tumor Growth after Subtotal Resection of Vestibular Schwannoma

Introduction  Vestibular schwannoma (VS) behavior following subtotal resection (STR) is highly variable. Overall progression rates have been reported as high as 44%, and optimal treatment is controversial. Correspondingly, identification of a reliable clinical or pathologic marker associated with progression after STR would help guide decision-making. Methods  A prospectively maintained institutional VS registry from 1999 to 2014 was retrospectively reviewed for sporadic VS patients who underwent primary STR without preceding stereotactic radiosurgery (SRS) by a single neurosurgery-neurotology team. Primary endpoints included tumor progression and postoperative facial nerve function. Pathologic specimens were stained for Ki67, CD68, S100, and SOX10 and were quantitated by digital imaging analysis. Macrophage density was defined as the ratio of CD68 ⁺ macrophages to S100 ⁺ macrophages and Schwannian tumor cells. Clinical outcomes were correlated with pathologic markers. Results  Forty-six patients met the study inclusion criteria. Thirteen (28%) progressed during a mean 57 months of follow-up (range 15-149). Favorable postoperative facial nerve function (House-Brackmann I-II) was achieved in 37 (80%). CD68 ⁺ cells were present at significantly higher concentrations in tumors that progressed ( p  = 0.03). Higher macrophage density was significantly associated with both tumor progression ( p  = 0.02) and unfavorable facial nerve function ( p  = 0.02). Ki67 percent positivity was not significantly associated with either primary endpoint ( p  = 0.83; p  = 0.58). Conclusions   Macrophage density may provide an important marker for individuals at the highest risk for progression of VS after STR, potentially prompting closer surveillance or consideration for upfront SRS following STR. This finding supports preceding conclusions that an intratumoral macrophage-predominant inflammatory response may be a marker for tumor growth and a potential therapeutic target.