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Antiangiogenic therapy has shown clear activity and improved survival benefit for certain tumor types. However, an incomplete understanding of the mechanisms of action of antiangiogenic agents has hindered optimization and broader application of this new therapeutic modality. In particular, the impact of antiangiogenic therapy on tumor blood flow and oxygenation status (i.e., the role of vessel pruning versus normalization) remains controversial. This controversy has become critical as multiple phase III trials of anti-VEGF agents combined with cytotoxics failed to show overall survival benefit in newly diagnosed glioblastoma (nGBM) patients and several other cancers. Here, we shed light on mechanisms of nGBM response to cediranib, a pan-VEGF receptor tyrosine kinase inhibitor, using MRI techniques and blood biomarkers in prospective phase II clinical trials of cediranib with chemoradiation vs. chemoradiation alone in nGBM patients. We demonstrate that improved perfusion occurs only in a subset of patients in cediranib-containing regimens, and is associated with improved overall survival in these nGBM patients. Moreover, an increase in perfusion is associated with improved tumor oxygenation status as well as with pharmacodynamic biomarkers, such as changes in plasma placenta growth factor and sVEGFR2. Finally, treatment resistance was associated with elevated plasma IL-8 and sVEGFR1 posttherapy. In conclusion, tumor perfusion changes after antiangiogenic therapy may distinguish responders vs. nonresponders early in the course of this expensive and potentially toxic form of therapy, and these results may provide new insight into the selection of glioblastoma patients most likely to benefit from anti-VEGF treatments.

NF2 -related schwannomatosis ( NF2 -SWN) is a debilitating condition, characterized by bilateral vestibular schwannomas (VSs) that progressively cause irreversible sensorineural hearing loss. Current management relies on surgery or radiotherapy, while bevacizumab (αVEGF) is used off-label, with variable and often transient efficacy. Effective therapies that durably suppress tumor growth and preserve hearing are urgently needed. Although immune checkpoint inhibitors have transformed cancer treatment, their efficacy in non-malignant tumors such as VS remains unclear. Here, we evaluate combined anti-PD1 (αPD1) and αVEGF therapy in two syngeneic, immune-competent VS models. Combination treatment significantly outperforms either monotherapy, inhibiting tumor growth and preventing hearing loss. Mechanistically, αVEGF enhances αPD1 efficacy by normalizing tumor vasculature, improving drug delivery and immune cell infiltration, and promoting cytotoxicity of T and NK cells via NKG2D upregulation. Combined treatment effectively controls tumor growth that progresses despite anti-VEGF therapy. These findings support αPD1 and αVEGF combination therapy as a promising strategy for NF2 -SWN. Vestibular schwannomas that are caused by genetic mutations in the NF2 gene are hard to treat and lead to hearing loss. Here authors show in a mouse model that faithfully represents the human condition that combination therapy with anti-PD-1 and anti-VEGF inhibits tumor growth via normalizing the tumor vasculature and enhances T and NK cell antitumor cytotoxicity via upregulation of NKG2D.

Background Neurofibromatosis 1 (NF1) is a rare, neurogenetic disorder predisposing individuals to multiple tumors and other issues requiring expert care and regular health monitoring. We sought to assess U.S. patients’ access to specialized NF1 clinics and receipt of evidence-informed health surveillance. Methods An online survey was distributed to NF Registry participants in May 2021. Rate of NF1 clinic attendance and self-reported receipt of health surveillance amongst NF Registry participants was estimated using inverse propensity scores. Differences in these outcomes based on participant demographics were assessed using weighted logistic regression and robust linear regression, respectively. Results 322 individuals responded (160 adults, 162 parents; 4.7% overall response rate). We estimate that 51.7% of children and 35.6% of adults attend NF1 clinics. Younger children were more likely to attend an NF1 clinic, as were adults living in urban areas, with a college degree or higher, or with a household income ≥ $130,000 (all ps < 0.05). Completion rates for each individual health surveillance evaluation ranged from 41 to 79% for children and 33–61% for adults. Higher rates of recommended evaluations were reported by both adults and children who attend a specialized NF1 clinic, non-Hispanic White adults, and adults with commercial or Medicare insurance (all ps < 0.05). Conclusions Adults with NF1 experience significant sociodemographic disparities in care, and patients of all ages attending NF1 specialty clinics receive more recommended health surveillance. Given the limited access to specialty NF clinics, quality improvement efforts are needed to increase access for underserved adults and improve provision of recommended health surveillance outside specialty clinics.

Schwannomatosis (SWNTS) is a genetic cancer predisposition syndrome that manifests as multiple and often painful neuronal tumors called schwannomas (SWNs). While germline mutations in SMARCB1 or LZTR1, plus somatic mutations in NF2 and loss of heterozygosity in chromosome 22q have been identified in a subset of patients, little is known about the epigenomic and genomic alterations that drive SWNTS-related SWNs (SWNTS-SWNs) in a majority of the cases. We performed multiplatform genomic analysis and established the molecular signature of SWNTS-SWNs. We show that SWNTS-SWNs harbor distinct genomic features relative to the histologically identical non-syndromic sporadic SWNs (NS-SWNS). We demonstrate the existence of four distinct DNA methylation subgroups of SWNTS-SWNs that are associated with specific transcriptional programs and tumor location. We show several novel recurrent non-22q deletions and structural rearrangements. We detected the SH3PXD2A-HTRA1 gene fusion in SWNTS-SWNs, with predominance in LZTR1-mutant tumors. In addition, we identified specific genetic, epigenetic, and actionable transcriptional programs associated with painful SWNTS-SWNs including PIGF, VEGF, MEK, and MTOR pathways, which may be harnessed for management of this syndrome.

Bevacizumab treatment can result in tumor shrinkage of progressive vestibular schwannomas in some neurofibromatosis 2 (NF2) patients but its effect on meningiomas has not been defined. To determine the clinical activity of bevacizumab against NF2-related meningiomas, we measured changes in volume of meningiomas in NF2 patients who received bevacizumab for treatment of progressive vestibular schwannomas. A radiographic response was defined as a 20% decrease in tumor size by volumetric MRI analysis. In addition, we determined the expression pattern of growth factors associated with tumor angiogenesis in paraffin-embedded tissues from 26 unrelated meningiomas. A total of 48 meningiomas in 15 NF2 patients were included in this study with a median follow up time of 18 months. A volumetric radiographic response was seen in 29% of the meningiomas (14/48). Tumor shrinkage was not durable: the median duration of response was 3.7 months and the median time to progression was 15 months. There was no significant correlation between pre-treatment growth rate and meningioma response in regression models. Tissue analysis showed no correlation between tumor microvascular density and expression of VEGF pathway components. This data suggests that, in contrast to schwannomas, activation of VEGF pathway is not the primary driver of angiogenesis in meningiomas. Our results suggest that a minority of NF2-associated meningiomas shrink during bevacizumab therapy and that these responses were of short duration. These results are comparable to previous studies of bevacizumab in sporadic meningiomas.

Patients with neurofibromatosis 1 (NF1), NF2, and schwannomatosis are at risk for multiple nerve sheath tumors and premature mortality. Traditional magnetic resonance imaging (MRI) has limited ability to assess disease burden accurately. The aim of this study was to establish an international cohort of patients with quantified whole-body internal tumor burden and to correlate tumor burden with clinical features of disease. We determined the number, volume, and distribution of internal nerve sheath tumors in patients using whole-body MRI (WBMRI) and three-dimensional computerized volumetry. We quantified the distribution of tumor volume across body regions and used unsupervised cluster analysis to group patients based on tumor distribution. We correlated the presence and volume of internal tumors with disease-related and demographic factors. WBMRI identified 1286 tumors in 145/247 patients (59%). Schwannomatosis patients had the highest prevalence of tumors (P = 0.03), but NF1 patients had the highest median tumor volume (P = 0.02). Tumor volume was unevenly distributed across body regions with overrepresentation of the head/neck and pelvis. Risk factors for internal nerve sheath tumors included decreasing numbers of café-au-lait macules in NF1 patients (P = 0.003) and history of skeletal abnormalities in NF2 patients (P = 0.09). Risk factors for higher tumor volume included female gender (P = 0.05) and increasing subcutaneous neurofibromas (P = 0.03) in NF1 patients, absence of cutaneous schwannomas in NF2 patients (P = 0.06), and increasing age in schwannomatosis patients (p = 0.10). WBMRI provides a comprehensive phenotype of neurofibromatosis patients, identifies distinct anatomic subgroups, and provides the basis for investigating molecular biomarkers that correlate with unique disease manifestations.

Hearing loss is the main limitation of radiation therapy for vestibular schwannoma (VS), and identifying treatment options that minimize hearing loss are urgently needed. Treatment with bevacizumab is associated with tumor control and hearing improvement in neurofibromatosis type 2 (NF2) patients; however, its effect is not durable and its mechanism of action on nerve function is unknown. We modeled the effect anti-VEGF therapy on neurological function in the sciatic nerve model and found that it improves neurological function by alleviating tumor edema, which may further improve results by decreasing muscle atrophy and increasing nerve regeneration. Using a cranial window model, we showed that anti-VEGF treatment may achieve these effects via normalizing the tumor vasculature, improving vessel perfusion, and delivery of oxygenation. It is known that oxygen is a potent radiosensitizer; therefore, we further demonstrated that combining anti-VEGF with radiation therapy can achieve a better tumor control and help lower the radiation dose and, thus, minimize radiation-related neurological toxicity. Our results provide compelling rationale for testing combined therapy in human VS.

Neurofibromatosis type II (NF2) is a disease that needs new solutions. Vestibular schwannoma (VS) growth causes progressive hearing loss, and the standard treatment, including surgery and radiotherapy, can further damage the nerve. There is an urgent need to identify an adjunct therapy that, by enhancing the efficacy of radiation, can help lower the radiation dose and preserve hearing. The mechanisms underlying deafness in NF2 are still unclear. One of the major limitations in studying tumor-induced hearing loss is the lack of mouse models that allow hearing testing. Here, we developed a cerebellopontine angle (CPA) schwannoma model that faithfully recapitulates the tumor-induced hearing loss. Using this model, we discovered that cMET blockade by crizotinib (CRZ) enhanced schwannoma radiosensitivity by enhancing DNA damage, and CRZ treatment combined with low-dose radiation was as effective as high-dose radiation. CRZ treatment had no adverse effect on hearing; however, it did not affect tumor-induced hearing loss, presumably because cMET blockade did not change tumor hepatocyte growth factor (HGF) levels. This cMET gene knockdown study independently confirmed the role of the cMET pathway in mediating the effect of CRZ. Furthermore, we evaluated the translational potential of cMET blockade in human schwannomas. We found that human NF2-associated and sporadic VSs showed significantly elevated HGF expression and cMET activation compared with normal nerves, which correlated with tumor growth and cyst formation. Using organoid brain slice culture, cMET blockade inhibited the growth of patient-derived schwannomas. Our findings provide the rationale and necessary data for the clinical translation of combined cMET blockade with radiation therapy in patients with NF2.

Purpose Bevacizumab treatment is associated with tumor shrinkage and hearing improvement in about 50 % of neurofibromatosis 2 (NF2) patients with progressive vestibular schwannomas. Hypertension and proteinuria are common side effects of treatment. However, the long-term toxicity of bevacizumab in this population has not been reported. Methods We reviewed the medical records of all NF2 patients treated with compassionate care bevacizumab at our institution. Hypertension was defined as a systolic blood pressure ≥140 or a diastolic blood pressure ≥90. Proteinuria was measured by urine dipstick. Time-to-event analyses were conducted for hypertension and proteinuria. The relationship of cumulative dose of bevacizumab to mean arterial pressure (MAP) was examined using mixed model analysis, while the relationship to urine protein was examined using generalized estimating equations. Results Thirty-three patients (median age 28 years) were included in the study, with a median treatment time of 34.1 months. 15/26 (58 %) patients became hypertensive and 18/29 (62 %) developed proteinuria during treatment. Median time to develop hypertension was 12.8 months. Median time to develop 1+ and 2+ proteinuria was 23.7 and 31.9 months, respectively. Eight patients required treatment holidays for proteinuria (median length 3.2 months). A significant positive relationship existed between cumulative bevacizumab dose and MAP ( p  < 0.0001) but not between cumulative dose and proteinuria ( p  > 0.30). Conclusion In our cohort of NF2 patients, extended use of bevacizumab was associated with manageable toxicity. However, bevacizumab treatment still requires careful monitoring of blood pressure and proteinuria, and future studies should investigate optimal dosing schedules to minimize long-term toxicity.

Purpose The coronavirus disease 2019 (COVID-19) pandemic has had unprecedented impact on the provision of medical care for genetic disorders. The purpose of this study was to assess the effects of the pandemic on neurofibromatosis (NF) care and research. Methods Sixty-three United States NF clinics were surveyed to identify the impact of the pandemic on clinician role, patient volume, continuity of guideline-driven surveillance, research protocols, and use of (and satisfaction with) telehealth for the delivery of NF care. Results Fifty-two clinic directors or their representatives completed the survey (83% response rate). About 2/3 of the clinics reported a greater than 50% decrease in the number of available patient appointments, and modified clinical surveillance and research protocols. Fifty-one clinics (98%) newly instituted telehealth during the pandemic. Barriers to telehealth prior to the pandemic were insurance reimbursement concerns and lack of infrastructure. Since telehealth was initiated, high provider satisfaction was reported with ease of use. The most common area of concern was related to inability to perform a physical examination. Conclusion Results show marked impacts on NF care and research since the beginning of the pandemic, with potential long-term changes related to the introduction (or adoption) of telehealth for clinical care.