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-related schwannomatosis ( -SWN, formerly called neurofibromatosis type 2) is a tumor predisposition syndrome that is manifested by multiple vestibular schwannomas, nonvestibular schwannomas, meningiomas, and ependymomas. The condition is relentlessly progressive with no approved therapies. On the basis of preclinical activity of brigatinib (an inhibitor of multiple tyrosine kinases) in -driven nonvestibular schwannoma and meningioma, data were needed on the use of brigatinib in patients with multiple types of progressive -SWN tumors. In this phase 2 platform trial with a basket design, patients who were 12 years of age or older with -SWN and progressive tumors were treated with oral brigatinib at a dose of 180 mg daily. A central review committee evaluated one target tumor and up to five nontarget tumors in each patient. The primary outcome was radiographic response in target tumors. Key secondary outcomes were safety, response rate in all tumors, hearing response, and patient-reported outcomes. A total of 40 patients (median age, 26 years) with progressive target tumors (10 vestibular schwannomas, 8 nonvestibular schwannomas, 20 meningiomas, and 2 ependymomas) received treatment with brigatinib. After a median follow-up of 10.4 months, the percentage of tumors with a radiographic response was 10% (95% confidence interval [CI], 3 to 24) for target tumors and 23% (95% CI, 16 to 30) for all tumors; meningiomas and nonvestibular schwannomas had the greatest benefit. Annualized growth rates decreased for all tumor types during treatment. Hearing improvement occurred in 35% (95% CI, 20 to 53) of eligible ears. Exploratory analyses suggested a decrease in self-reported pain severity during treatment (-0.013 units per month; 95% CI, -0.002 to -0.029) on a scale from 0 (no pain) to 3 (severe pain). No grade 4 or 5 treatment-related adverse events were reported. Brigatinib treatment resulted in radiographic responses in multiple tumor types and clinical benefit in a heavily pretreated cohort of patients with -SWN. (Funded by the Children's Tumor Foundation and others; INTUITT-NF2 ClinicalTrials.gov number, NCT04374305.).

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.

Neurofibromatosis type 2 (NF2) is a rare disorder that causes vestibular schwannomas (VS), meningiomas and ependymomas. To date, there is no FDA approved drug-based treatment for NF2. We have previously identified that BET inhibition can selectively reduce growth of the NF2 -null schwannoma and Schwann cells in vitro and tumorigenesis in vivo and, separately, reported that inhibition of Focal Adhesion Kinase 1 (FAK1) via crizotinib has antiproliferative effects in NF2-null Schwann cells. The current study was aimed at determining whether combined BET and FAK inhibition can synergize and to identify the mechanisms of action. A panel of normal and NF2-null Schwann and schwannoma cell lines were used to characterize the effects of combined BET and FAK inhibition in vitro and in vivo using pharmacological and genetic approaches. The mechanism of action was explored by chromatin immunoprecipitation, ChIP-PCR, western blotting, and functional approaches. We find that combined BET and FAK inhibition are synergistic and inhibit the proliferation of NF2 -null schwannoma and Schwann cell lines in vitro and in vivo, by arresting cells in the G1/S and G2/M phases of the cell cycle. Further, we identify the mechanism of action through the downregulation of FAK1 transcription by BET inhibition, which potentiates inhibition of FAK by 100-fold. Our findings suggest that combined targeting of BET and FAK1 may offer a potential therapeutic option for the treatment of NF2-related schwannomas.

Neurofibromatosis Type 2 (NF2) is an autosomal dominant genetic syndrome caused by mutations in the NF2 tumor suppressor gene resulting in multiple schwannomas and meningiomas. There are no FDA approved therapies for these tumors and their relentless progression results in high rates of morbidity and mortality. Through a combination of high throughput screens, preclinical in vivo modeling, and evaluation of the kinome en masse , we identified actionable drug targets and efficacious experimental therapeutics for the treatment of NF2 related schwannomas and meningiomas. These efforts identified brigatinib (ALUNBRIG ® ), an FDA-approved inhibitor of multiple tyrosine kinases including ALK, to be a potent inhibitor of tumor growth in established NF2 deficient xenograft meningiomas and a genetically engineered murine model of spontaneous NF2 schwannomas. Surprisingly, neither meningioma nor schwannoma cells express ALK. Instead, we demonstrate that brigatinib inhibited multiple tyrosine kinases, including EphA2, Fer and focal adhesion kinase 1 (FAK1). These data demonstrate the power of the de novo unbiased approach for drug discovery and represents a major step forward in the advancement of therapeutics for the treatment of NF2 related malignancies.

Neurofibromatosis type 2 (NF2)-related schwannomatosis is an autosomal dominant genetic disorder characterized by the development of cranial and peripheral nerve schwannomas, including bilateral vestibular schwannomas which are associated with substantial morbidity. Current therapeutic strategies comprise surgical resection, radiotherapy, and systemic administration of bevacizumab; however, these approaches are frequently limited by high recurrence rates and morbidity. In this study, a transgenic murine model ( Postn-Cre;Nf2 flox/flox ) was employed to investigate the combined effect of intraperitoneally administered human bevacizumab (5 mg/kg b. w.) and focused ultrasound (FUS) on drug delivery and tumor growth in DRG schwannomas. ELISA-based analysis demonstrated a 3.8-fold increase in intratumoral bevacizumab concentration following the combined application of human bevacizumab and FUS, compared to bevacizumab alone. Tumor growth was assessed using 7-T MRI of the spine with intravenous gadolinium contrast, and outcomes were compared across five experimental groups: (1) human bevacizumab alone, (2) murine bevacizumab alone, (3) human bevacizumab combined with FUS, (4) FUS alone, and (5) untreated controls. Treatments, including drug administration and FUS exposure, were performed three times at two-week intervals. Notably, the combined treatment group (human bevacizumab + FUS) exhibited a trend toward tumor size reduction.

Extracellular vesicles present an attractive delivery vehicle for therapeutic proteins. They intrinsically contain many proteins which can provide information to other cells. Advantages include reduced immune reactivity, especially if derived from the same host, stability in biologic fluids, and ability to target uptake. Those from mesenchymal stem cells appear to be intrinsically therapeutic, while those from cancer cells promote tumor progression. Therapeutic proteins can be loaded into vesicles by overexpression in the donor cell, with oligomerization and membrane sequences increasing their loading. Examples of protein delivery for therapeutic benefit in pre-clinical models include delivery of: catalase for Parkinson’s disease to reduce oxidative stress and thus help neurons to survive; prodrug activating enzymes which can convert a prodrug which crosses the blood–brain barrier into a toxic chemotherapeutic drug for schwannomas and gliomas; and the apoptosis-inducing enzyme, caspase-1 under a Schwann cell specific promoter for schwannoma. This therapeutic delivery strategy is novel and being explored for a number of diseases.

Purpose Bevacizumab treatment is associated with imaging and hearing responses in progressive vestibular schwannoma (VS) caused by NF2 -related schwannomatosis ( NF2 -SWN). However, its effect on co-existing intracranial non-vestibular schwannomas (NVS) and meningiomas is unclear. Methods We retrospectively analyzed tumor volumes of non-target intracranial NVS and meningiomas in patients with NF2 -SWN and progressive VS who were prospectively treated with bevacizumab for two years on the Neurofibromatosis Clinical Trials Consortium (NFCTC) trial NF104 (NCT01767792). Radiographic response (RR) or progression (PD) were defined as ≥ 20% decrease or ≥ 20% increase in tumor volume compared to baseline, respectively. All other responses were defined as stable disease. Results A total of 40 meningiomas in eight patients and 12 NVS in six patients were evaluated across 22 enrolled trial participants. On best response analysis, RR occurred in 13% (5/40) of meningiomas and in 42% (5/12) of NVS. On a per-patient basis, RR for meningioma occurred in 38% (3/8) of patients and for NVS in 67% (4/6) of patients. RR in two NVS were durable throughout the study period. During two years of treatment, PD occurred in 55% (22/40) of meningiomas and in 8% (1/12) of NVS. Median time to tumor progression was 15 months for meningiomas and was not reached for NVS. Conclusions We observed greater activity of bevacizumab against intracranial NVS compared to meningioma, evidenced by more favorable RR rates, durability of response, and rates of PD. Potential biological differences between meningiomas and schwannomas that underlie this differential response to bevacizumab warrant further investigation.

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.

Neurofibromatosis Type 2 (NF2)-related schwannomatosis is a genetic disorder that causes development of multiple types of nervous system tumors. The primary and diagnostic tumor type is bilateral vestibular schwannoma. There is no cure or drug therapy for NF2. Recommended treatments include surgical resection and radiation, both of which can leave patients with severe neurological deficits or increase the risk of future malignant tumors. Results of our previous pilot high-throughput drug screen identified phosphoinositide 3-kinase (PI3K) inhibitors as strong candidates based on loss of viability of mouse merlin-deficient Schwann cells (MD-SCs). Here we used novel human schwannoma model cells to conduct combination drug screens. We identified a class I PI3K inhibitor, pictilisib and p21 activated kinase (PAK) inhibitor, PF-3758309 as the top combination due to high synergy in cell viability assays. Both single and combination therapies significantly reduced growth of mouse MD-SCs in an orthotopic allograft mouse model. The inhibitor combination promoted cell cycle arrest and apoptosis in mouse merlin-deficient Schwann (MD-SCs) cells and cell cycle arrest in human MD-SCs. This study identifies the PI3K and PAK pathways as potential targets for combination drug treatment of NF2-related schwannomatosis.

Neurofibromatosis type 2 (NF2) is a genetic disorder with bilateral vestibular schwannomas (VS) as the most frequent manifestation. Merlin, the NF2 tumor suppressor, was identified as a negative regulator of mammalian target of rapamycin complex 1. Pre-clinical data in mice showed that mTORC1 inhibition delayed growth of NF2-schwannomas. We conducted a prospective single-institution open-label phase II study to evaluate the effects of everolimus in ten NF2 patients with progressive VS. Drug activity was monitored every 3 months. Everolimus was administered orally for 12 months and, if the decrease in tumor volume was >20 % from baseline, treatment was continued for 12 additional months. Other patients stopped when completed 12 months of everolimus but were allowed to resume treatment when VS volume was >20 % during 1 year follow-up. Nine patients were evaluable. Safety was evaluated using CTCAE 3.0 criteria. After 12 months of everolimus, no reduction in volume ≥20 % was observed. Four patients had progressive disease, and five patients had stable disease with a median annual growth rate decreasing from 67 %/year before treatment to 0.5 %/year during treatment. In these patients, tumor growth resumed within 3–6 months after treatment discontinuation. Everolimus was then reintroduced and VS decreased by a median 6.8 % at 24 months. Time to tumor progression increased threefold from 4.2 months before treatment to > 12 months. Hearing was stable under treatment. The safety of everolimus was manageable. Although the primary endpoint was not reached, further studies are required to confirm the potential for stabilization of everolimus.