Search Results (17)

Background/Objectives: To characterize the clinical and imaging phenotypes of schwannomatosis (SWN) in children, adolescents, and young adults (AYAs). Methods: This single-center retrospective cohort study included patients (age ≤ 25 years) with suspected SWN with archived magnetic resonance imaging (MRI) at Johns Hopkins between 2020–2026. Clinical characteristics, genetic testing results, and tumor imaging (including anatomic distribution), and treatment approaches were reviewed. Descriptive statistics were performed. Results: In total, thirty-eight patients with suspected SWN were identified (median age 20 years, range 6–25; 32% female). NF2-related SWN was the most common diagnosis (31/38, 82%; de novo: 24/31 (77%) and familial: 7/31 (23%)), followed by LZTR1-SWN (n = 1) and SWN-NOS/NEC (n = 2). A total of four patients (asymptomatic LZTR1 carriers (n = 2) and possible SWN (n = 2)) did not fulfill diagnostic criteria based on craniospinal and whole-body MRI. Familial NF2-SWN demonstrated a trend toward earlier presentation (median 5 vs. 8 years; p = 0.12). Visual manifestations occurred at a younger age than hearing loss (median 8 vs. 16 years; p = 0.053). Imaging burden was high (median 23 MRI/patient (range: 1–60). Bilateral vestibular schwannomas were nearly universal (30/31, 97%). Familial disease demonstrated a trend toward increased cranial meningiomas (86% vs. 54%; p = 0.20), while peripheral schwannomas (43% vs. 67%; p = 0.38) and ependymomas (14% vs. 42%; p = 0.37) were less frequent compared with de novo disease. Operative and non-operative management was documented in 65% (20/31) each. Conclusions: NF2-related SWN is the predominant subtype in a pediatric and AYA patient population and was associated with substantial early tumor burden at a tertiary specialty NF center. Full article

Background/Objectives: NF2-related schwannomatosis (NF2-SWN) is a genetic tumor predisposition syndrome of the nervous system caused by pathogenic variants in NF2 encoding the merlin tumor suppressor. Truncating variants in NF2 cause severe phenotypes with higher tumor burden, early mortality, and a lifetime need for multiple surgeries due to lack of medications that control schwannoma growth. Methods: We developed a functional precision medicine (FPM)-inspired workflow to identify drug sensitivities in cells isolated from a pediatric severe NF2-SWN patient’s spinal and peripheral schwannomas. Transcriptomic profiling, high-content drug sensitivity assays, tissue and isolated cell immunostaining, flow cytometry, and capillary-based immunoblotting were used to study the available tissues. Results: Aberrant merlin-dependent pathway expression was conserved between the spinal schwannoma and its cultured primary cells. Drug sensitivity screens in 2- and 3-dimensional formats revealed cytotoxic effects of fimepinostat in primary cells; dasatinib with brigatinib was the most effective cytostatic combination. Ineffective therapies attempted in the patient were also ineffective ex vivo. Conclusions: These data support the idea of using the FPM workflow to improve and individualize the standard of care for severe NF2-SWN patients using surgical samples. Full article

Neurofibromatosis type 1 (NF1) and NF2-related schwannomatosis (NF2-SWN) are major genetic tumor predisposition syndromes characterized by progressive, often debilitating neoplasms of the peripheral and central nervous systems. Over the past five years, substantial advances in molecular genetics, signaling biology, and targeted therapeutic development have reshaped diagnostic and management paradigms for both disorders. This Perspective synthesizes recent developments, including gene-based reclassification, emergence of MEK inhibitor therapy in NF1, renewed evaluation of bevacizumab and kinase-pathway inhibitor brigatinib, the discovery of a novel TβR1-RKIP pathogenic axis, and a brain-penetrant HDAC inhibitor in NF2-SWN. These insights highlight a shift toward precision-medicine strategies and mechanistically driven therapies poised to redefine future clinical care. Full article

There is no approved drug therapy for schwannomas associated with NF2-related schwannomatosis (NF2-SWN). Neither life-saving surgical resection or radiation are curative and can compound the debilitating neurological effects of the schwannomas. We previously identified fimepinostat, a dual histone deacetylase (HDAC)/phosphoinositide-3 kinase (PI3K) inhibitor, as a promising drug candidate with pro-apoptotic effects on NF2-related schwannomas. This preclinical study used the pharmaceutical formulation of fimepinostat to confirm its efficacy in schwannomas and identify pro-apoptotic signaling pathways. Fimepinostat was tested in human schwannoma model cells, patient-derived primary vestibular and non-vestibular schwannoma cells, and in a sciatic nerve allograft model. The signaling pathways leading to caspase-3-dependent apoptosis were elucidated using immune assays, flow cytometry, imaging, proteome, and acetylome analysis. Acute exposure to fimepinostat led to p21-dependent cell cycle inhibition, upregulation of tumor necrosis factor-related apoptosis-inducing ligand receptor 2 (TRAIL R2), and downregulation of tumor necrosis factor receptor 1 (TNFR1), Yes-associated protein (YAP), and inhibitors of apoptosis. Moreover, fimepinostat downregulated cytokine and chemokine secretion increased by merlin loss in schwannoma cells. Fimepinostat is a promising new drug intervention for NF2-SWN patients with the potential to promote tumor regression. Full article

NF2-related Schwannomatosis (NF2-SWN) remains a disorder with few effective treatment options. Patients develop vestibular schwannomas (VSs) on both auditory nerves, which gradually impair hearing and often result in significant communication difficulties, social withdrawal, and higher rates of depression. Progress in understanding NF2-SWN biology and translating discoveries into therapies has been slowed by the absence of robust animal models that faithfully reproduce both tumor behavior and the associated neurological deficits. In this review, we summarized the development of animal models that not only reproduce tumor growth in the peripheral nerve microenvironment but also reproduce tumor-induced neurological symptoms, such as hearing loss and ataxia. We further highlight the currently available organotypic models for NF2-SWN. Together, these systems provide an essential foundation for advancing mechanistic studies and accelerating the development of effective therapies for this devastating disorder. Full article

In-depth exploration of tumor immune suppression mechanisms may provide new therapeutic options for NF2-associated tumors. In this study, we found that sEVs secreted by NF2-associated schwannomas (NF2-EVs) facilitate the conversion of CD14⁺ monocytes into an MDSC-like phenotype, showcasing MDSC-like inhibitory functions. Moreover, these NF2-EVs are capable of enhancing tumor cell proliferation. Through proteomic analysis and subsequent validation of the NF2-EVs, we identified elevated levels of HSP90. When we knocked down HSP90 expression in tumor cells, the sEVs secreted showed diminished capacity to convert monocytes into MDSCs and a reduced ability to promote tumor cell proliferation. Conversely, sEVs secreted by tumor cells that overexpress HSP90 displayed the opposite effects. Further mechanistic studies revealed that HSP90 could influence the expression of AKT/p-AKT and ERK/p-ERK. Our results suggest that NF2 tumor cells could regulate the AKT/p-AKT and ERK/p-ERK pathways to promote tumor cell proliferation and the formation of an immunosuppressive microenvironment by secreting sEVs’ HSP90, offering valuable insights into the involvement of HSP90 in exosome-mediated communication within the context of NF2-related schwannomatosis (NF2-SWN). This information has the potential to inform the design of effective immunotherapeutic protocols and offer new treatment options for NF2-SWN patients. Full article

We report the first case of pleural mesothelioma (PM) occurring in a child affected by NF2-related schwannomatosis (NF2-SWN) and without any history of environmental exposure to asbestos. Mesothelioma is a rare secondary tumor in brain cancer patients and the association with NF2-SWN has been described only in a few anecdotal cases and never in the pediatric field. NF2-SWN is an autosomal dominant disease caused by inactivating germline mutations of the NF2 tumor suppressor gene, one of the most common mutations associated with human primary mesothelioma too. By MLPA assay, array-CGH analysis, and NGS on blood and tumor DNA, we determined the mutation profile of this rare NF2-driven PM and we identified several atypical chromosomal aberrations in tumor cells, suggesting a different genomic signature between pediatric and adult mesothelioma. Full article

Background/Objectives: NF2-related schwannomatosis (NF2) is a tumor predisposition syndrome that typically presents with bilateral vestibular schwannomas, together with other intracranial and spinal schwannomas, meningiomas, and/or ependymomas. Bevacizumab, a VEGF inhibitor, has the potential to decrease schwannoma volume and improve hearing in adults, but the literature on the effects in children is sparse. This narrative review aims to evaluate the use of bevacizumab in pediatric NF2 patients, focusing on hearing, tumor progression, and toxicity. Methods: A literature review was conducted following PRISMA guidelines. Articles were searched in PubMed, Embase, Web of Science, Cochrane Library, Emcare, and Academic Search Premier on 18 July 2024. Inclusion criteria were patients ≤ 18 years, diagnosed with NF2 and treated with bevacizumab. Two authors independently assessed the quality of the evidence and extracted relevant data from the included articles. Results: Seventeen articles including 62 pediatric NF2 patients met the inclusion criteria. Studies varied widely in treatment regimens and outcome parameters. Tumor regression was reported in 6/56 patients (11%) and 38/56 (68%) remained stable. Hearing improved in 15/45 patients (33%) and did not further deteriorate in 27/45 (60%). An improvement in other symptoms was seen in 6/29 patients (28%). Toxicity was reported in five studies, documenting 13 adverse events in 28 patients ranging from grade 1 to grade 3. Treatment was discontinued in both patients who experienced grade 3 toxicity. Conclusions: Bevacizumab seems to be a viable treatment option for pediatric NF2 patients. Tumor regression or stabilization is achieved in the majority of patients (77%). Moreover, a considerable number of pediatric patients experience hearing stabilization or improvement (93%). Bevacizumab appears to be relatively well tolerated, offering a non-invasive therapeutic option for children with NF2 suffering from progressive vestibular schwannomas and hearing loss. Full article

Background: Unilateral (uVS) and bilateral vestibular schwannoma (bVS) are distinct disease types, yet share tumorigenic features. This study examined causative genetic alterations in three groups: patients with NF2-related schwannomatosis (NF2), young patients with uVS (≤30 years), and older patients with uVS (≥40 years). Methods: Lymphocyte and vestibular schwannoma DNA was genetically analyzed. Outcomes included gene involvement, pathogenicity classification, variant type, effect, and location, and loss of heterozygosity (LOH) of chromosome 22. Results: Among 93 patients, 17% had NF2, 39% were ≤30 years with uVS, and 44% were ≥40 years with uVS. In all patients with NF2 (100%), two or more hits were detected in the tumor DNA, whereas patients with uVS had a slightly lower detection rate (89–98%). NF2-related tumors had a higher frequency of nucleotide variants (76%), while LOH events were more common in uVS (64–69%). Variants were mostly identified in NF2, with nonsense variants over-represented in patients with NF2 (38%) and frameshift variants more prevalent in uVS (44–51%). Conclusions: Biallelic NF2 inactivation primarily drives vestibular schwannoma tumorigenesis. In patients with NF2, two pathogenic NF2 variants or one NF2 variant with LOH are common, whereas patients with uVS often exhibit one NF2 variant with LOH. Additionally, variant types differ between patient groups. Full article

NF2-related schwannomatosis (NF2) is a genetic syndrome characterized by the growth of benign tumors in the nervous system, particularly bilateral vestibular schwannomas, meningiomas, and ependymomas. This review consolidates the current knowledge on NF2 syndrome, emphasizing the molecular pathology associated with the mutations in the gene of the same name, the NF2 gene, and the subsequent dysfunction of its product, the Merlin protein. Merlin, a tumor suppressor, integrates multiple signaling pathways that regulate cell contact, proliferation, and motility, thereby influencing tumor growth. The loss of Merlin disrupts these pathways, leading to tumorigenesis. We discuss the roles of another two proteins potentially associated with NF2 deficiency as well as Merlin: Yes-associated protein 1 (YAP), which may promote tumor growth, and Raf kinase inhibitory protein (RKIP), which appears to suppress tumor development. Additionally, this review discusses the efficacy of various treatments, such as molecular therapies that target specific pathways or inhibit neomorphic protein–protein interaction caused by NF2 deficiency. This overview not only expands on the fundamental understanding of NF2 pathophysiology but also explores the potential of novel therapeutic targets that affect the clinical approach to NF2 syndrome. Full article

NF2-related Schwannomatosis (NF2-SWN) is a disease that needs new solutions. The hallmark of NF2-SWN, a dominantly inherited neoplasia syndrome, is bilateral vestibular schwannomas (VSs), which progressively enlarge, leading to sensorineural hearing loss, tinnitus, facial weakness, and pain that translates to social impairment and clinical depression. Standard treatments for growing VSs include surgery and radiation therapy (RT); however, both carry the risk of further nerve damage that can result in deafness and facial palsy. The resultant suffering and debility, in combination with the paucity of therapeutic options, make the effective treatment of NF2-SWN a major unmet medical need. A better understanding of these mechanisms is essential to developing novel therapeutic targets to control tumor growth and improve patients’ quality of life. Previously, we developed the first orthotopic cerebellopontine angle mouse model of VSs, which faithfully mimics tumor-induced hearing loss. In this model, we observed that mice exhibit symptoms of ataxia and vestibular dysfunction. Therefore, we further developed a panel of five tests suitable for the mouse VS model and investigated how tumor growth and treatment affect gait, coordination, and motor function. Using this panel of ataxia tests, we demonstrated that both ataxia and motor function deteriorated concomitantly with tumor progression. We further demonstrated that (i) treatment with anti-VEGF resulted in tumor size reduction, mitigated ataxia, and improved rotarod performance; (ii) treatment with crizotinib stabilized tumor growth and led to improvements in both ataxia and rotarod performance; and (iii) treatment with losartan did not impact tumor growth nor ameliorate ataxia or motor function. Our studies demonstrated that these methods, paired with hearing tests, enable a comprehensive evaluation of tumor-induced neurological deficits and facilitate the assessment of the effectiveness of novel therapeutics to improve NF2 treatments. Full article

(1) Background: NF2-related schwannomatosis, characterized by the development of bilateral vestibular schwannomas, often necessitates varied treatment approaches. Bevacizumab, though widely utilized, demonstrates variable effectiveness on hearing and tumor growth. At the same time, (serious) adverse events have been frequently reported. (2) Methods: A single center retrospective study was conducted, on NF2-related schwannomatosis patients treated with bevacizumab from 2013 to 2023, with the aim to assess treatment-related and clinical outcomes. Outcomes of interest comprised hearing, radiologic response, symptoms, and adverse events. (3) Results: Seventeen patients received 7.5 mg/kg bevacizumab for 7.1 months. Following treatment, 40% of the patients experienced hearing improvement, 53%, stable hearing, and 7%, hearing loss. Vestibular schwannoma regression occurred in 31%, and 69% remained stable. Further symptomatic improvement was reported by 41%, stable symptoms by 47%, and worsened symptoms by 12%. Treatment discontinuation due to adverse events was observed in 29% of cases. Hypertension (82%) and fatigue (29%) were most frequently reported, with no occurrences of grade 4/5 toxicities. (4) Conclusion: Supporting previous studies, bevacizumab demonstrated positive effects on hearing, tumor control, and symptoms in NF2-related schwannomatosis, albeit with common adverse events. Therefore, careful consideration of an appropriate management strategy is warranted. Full article

Vestibular schwannoma (VS) are benign cranial nerve sheath tumors of the vestibulocochlear nerve. Their incidence is mostly sporadic, but they can also be associated with NF2-related schwannomatosis (NF2), a hereditary tumor syndrome. Metastasis associated in colon cancer 1 (MACC1) is known to contribute to angiogenesis, cell growth, invasiveness, cell motility and metastasis of solid malignant cancers. In addition, MACC1 may be associated with nonsyndromic hearing impairment. Therefore, we evaluated whether MACC1 may be involved in the pathogenesis of VS. Sporadic VS, recurrent sporadic VS, NF2-associated VS, recurrent NF2-associated VS and healthy vestibular nerves were analyzed for MACC1 mRNA and protein expression by quantitative polymerase chain reaction and immunohistochemistry. MACC1 expression levels were correlated with the patients’ clinical course and symptoms. MACC1 mRNA expression was significantly higher in sporadic VS compared to NF2-associated VS (p < 0.001). The latter expressed similar MACC1 concentrations as healthy vestibular nerves. Recurrent tumors resembled the MACC1 expression of the primary tumors. MACC1 mRNA expression was significantly correlated with deafness in sporadic VS patients (p = 0.034). Therefore, MACC1 might be a new molecular marker involved in VS pathogenesis. Full article

(1) Background: This study aimed to evaluate the efficacy and treatment-related toxicity of proton radiotherapy (PRT) for vestibular schwannoma (VS) in patients with neurofibromatosis type 2-related schwannomatosis (NF2). (2) Methods: Consecutive NF2 patients treated with PRT for VS between 2004 and 2016 were retrospectively evaluated, focusing on tumor volume, facial and trigeminal nerve function, hearing, tinnitus, vestibular symptoms, and the need for salvage therapy after PRT. (3) Results: Eight patients were included (median age 36 years, 50% female). Median follow-up was 71 months. Five (63%) patients received fractionated PRT and three (38%) received PRT radiosurgery for VS. Six patients (75%) received prior VS surgery; three also received bevacizumab. Six patients (75%) did not require salvage therapy after PRT. Two patients (25%) with residual hearing lost it after PRT, and six had already lost ipsilateral hearing prior to PRT. Tumor and treatment-related morbidity could be evaluated in six patients. Following PRT, conditions that occurred or worsened were: facial paresis in five (83%), trigeminal hypoesthesia in two (33%), tinnitus in two (33%), and vestibular symptoms in four patients (67%). (4) Conclusion: After PRT for VS, the majority of the NF2 patients in the cohort did not require additional therapy. Tumor and/or treatment-related cranial nerve deficits were common. This is at least partly explained by the use of PRT as a salvage treatment after surgery or bevacizumab, in the majority of cases. There remains the further opportunity to elucidate the efficacy and toxicity of proton radiotherapy as a primary treatment. Full article

Peripheral nerve sheath tumors encompass a wide spectrum of lesions with different biological behavior, including both benign and malignant neoplasms as well as the recent diagnostic category, i.e., “atypical neurofibromatous neoplasm with uncertain biologic potential” to be used only for NF1 patients. Neurofibromas and schwannomas are benign Schwann-cell-derived peripheral nerve sheath tumors arising as isolated lesions or within the context of classical neurofibromatosis or schwannomatoses. Multiple tumors are a hallmark of neurofibromatosis type 1(NF1) and related forms, NF2-related-schwannomatosis (formerly NF2) or SMARCB1/LZTR1-related schwannomatoses. Perineuriomas are benign, mostly sporadic, peripheral nerve sheath tumors that show morphological, immunohistochemical, and ultrastructural features reminiscent of perineurial differentiation. Hybrid tumors exist, with the most common lesions represented by a variable mixture of neurofibromas, schwannomas, and perineuriomas. Conversely, malignant peripheral nerve sheath tumors are soft tissue sarcomas that may arise from a peripheral nerve or a pre-existing neurofibroma, and in about 50% of cases, these tumors are associated with NF1. The present review emphasizes the main clinicopathologic features of each pathological entity, focusing on the diagnostic clues and unusual morphological variants. Full article