P18.11.A Active beam scanning proton therapy for large skull base benign meningiomas: long-term results

alexandrossfakianakis shared this article with you from Inoreader P18.11.A Active beam scanning proton therapy for large skull base benign meningiomas: long-term results via # Neuro-Oncology Current Issue Abstract Purpose To report long-term results of active beam scanning proton therapy (PT) for large skull base benign meningiomas Material and Methods Eighty-two patients (pts) with large skull base meningiomas were treated with PT between April 2015 and December 2021. Median age was 62 years (range, 48-82) while KPS ranged between 60 and 100 (median 90); 60 were female (73%), and 22 were male (27%). Thirty-two pts (39%) had histologically proven World Health Organization (WHO) Grade I tumors. In remaining pts diagnosis was based on the typical imaging appearance of benign meningioma. All patients received PT for residual, progressive or non-operable lesions. Newly diagnosed tumors received total dose of 50 GyRBE (RBE: relative biologic effectiveness) while progressing meningiomas 54 GyRBE. All the treatments were delivered at 2 GyRBE per fraction. All pts were treated with active beam scanning PT using 3 fields with single field optimiz ation technique. Treatment planning was based on morphological magnetic resonance imaging (MRI) with contrast enhancement medium administration. All pts received also 68-Ga-DOTATOC-PET. Gross tumor volume ranged from 21 to 64 cc. Toxicity was assessed according to Common Terminology Criteria for Adverse Events version 4.0. Median follow-up time was 40 months (range, 3-83). Results All pts completed the treatment without breaks. Registered acute side effects include grade 1 (19%) and grade 2 (8%) skin erythema, grade 1 (5%) and grade 2 (5%) alopecia, grade 1 (40%) fatigue, grade 1 (5%) and grade 2 (10%) conjunctivitis, grade 1 (10%) pain, grade 1 (5%) blurred vision, grade 1 (10%) headache, and grade 2 (5%) skin hyperpigmentation. One pts (1%) experienced grade 3 pain. There were no further grade 3 or higher acute toxicities. Registered late side effects include grade 1 (2%) and grade 2 (5%) alopecia, grade 1 (21%) fatigue, grade 1 (5%) and grade 2 (5%) headache, grade 1 (6% ) dizziness, grade 1 (3%) blurred vision, grade 1 (3%) and grade 2 (6%) pain, grade 1 (2%) dry eye, and grade 1 (5%) skin hyperpigmentation. Two pts (2%) experienced grade 3 pain. Two further pts (2%) experienced grade 3 optic neuropathy. There were no further grade 3 or higher late toxicities. During follow-up one pts (1%) with cavernous sinus meningioma experienced complete obstruction of intracavernous carotid artery with mild transient symptoms that resolved in few days and brain tissue ischemia detected at MRI (grade 2). Before irradiation this pts already had a meningioma-related near-complete obstruction of the intracavernous carotid artery and received a vascular surgery evaluation. Currently, absolute tumor control is 99%. Moreover, relief of symptoms recorded before irradiation occurred in 40% of pts. Conclusion PT is safe and effective treatment for pts with large skull base benign meningiomas. View on Web

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KS04.6.A Epidemiology of adult meningioma in the Netherlands: a population-based study

alexandrossfakianakis shared this article with you from Inoreader KS04.6.A Epidemiology of adult meningioma in the Netherlands: a population-based study via # Neuro-Oncology Current Issue Abstract Background Meningiomas are the most common primary tumours of the central nervous system. As the majority of meningiomas are benign, initial management often consists of observation only. Consequently, estimates on meningioma incidence are generally considered too low, with many registries mainly depending on pathology notifications. With additional notification sources, this study provides more complete population-based estimates on the incidence, prevalence, and prognostic impact of meningioma diagnosis in the Netherlands. Material and Methods Data on patients diagnosed with meningioma during 2000-2019 were obtained from the Netherlands Cancer Registry (NCR), which was expanded to the Dutch Brain Tumour Registry (DBTR) for meningiomas as of 2016. In addition to histological confirmations, the NCR/DBTR receives case notifications from hospital administrative registrations on cost reimbursement and outpatient care. In addition, a data linkage was performed with a clinical database maintained by one of the Dutch neuro-oncology centres to evaluate local completeness of the NCR/DBTR. Time trends of the age-adjusted incidence rates were evaluated by calculating the estimated annual percentage change (EAPC). Relative survival rates were calculated using the Pohar-Perme estimator. Results From 2000 to 2019, a total of 22,605 cases of meningioma were registered; 11,423 (50.5%) were histologically confirmed, while 11,182 (49.5%) had a radiological diagnosis. Over time, incidence increased from 4.7 per 100,000 inhabitants (European Standardized Rate, ESR) to 10.7 (EAPC 4.6%, p<0.01); the incidence of radiological diagnosis increased from 1.2 to 6.9 per 100,000 ESR (EAPC 9.6%, p<0.01). Local data completeness was estimated at 98% for histologically confirmed meningiomas and 87% for radiological diagnoses. On the basis of these incidence estimates, the prevalence of meningioma is estimated at 105/100, 000 on January 1st of 2020, with over 17,500 individuals having had a diagnosis of meningioma at that moment. Relative survival rate at 5 years for grade I meningiomas was 94.8% (95%-confidence interval: 94.0%-95.4%), 84.0% (95%CI: 81.0%-86.5%) for grade II meningiomas, and 47.3% (95%CI: 38.2%-55.8%) for grade III meningiomas. Conclusion As the incidence estimates in this study may be considered most complete, the results obtained should approximate the true incidence, prevalence, and prognostic impact of meningioma diagnosis in the Netherlands. View on Web

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P11.52.A Peripheral neuropathies after BRAF and/or MEK inhibitors treatment: a pharmacovigilance study

alexandrossfakianakis shared this article with you from Inoreader P11.52.A Peripheral neuropathies after BRAF and/or MEK inhibitors treatment: a pharmacovigilance study via # Neuro-Oncology Current Issue Abstract Background BRAF (BRAFi) and MEK inhibitors (MEKi) demonstrated significant efficacy in the treatment of BRAF-activated tumours, firstly melanoma. Nevertheless, they are not devoid of adverse events. Sparse reports in the literature suggest the potential occurrence of peripheral neuropathies (PN) under BRAFi/MEKi treatment, but their characteristics remain poorly defined. We aimed to characterize the clinical phenotypes of PN occurring under BRAFi/MEKi treatment using a national pharmacovigilance database. Material and Methods We queried the French pharmacovigilance database for all cases of PN toxicity attributed to at least one BRAFi or MEKi compound. Only cases with a least symptoms description and nerve conduction studies (NCS) conclusion were included. Results Sixteen cases of PN occurred in 15 patients were identified. All patients had underlying melanoma. Two main phenotypes were seen. Six patients (dabrafenib-tr ametinib, n=3; vemurafenib, n=2; vemurafenib-cobimetinib, n=1) presented a length-dependent axonal polyneuropathy: symptoms were mostly sensory at lower limbs; NCS disclosed an axonal neuropathy; management and outcome were variable. Nine patients (dabrafenib-trametinib, n=5, encorafenib-binimetinib, n=3, and vemurafenib-cobimetinib, n=1) developed a demyelinating polyradiculoneuropathy: symptoms affected the four limbs and included hypoesthesia, weakness, and ataxia; cranial nerves were involved in four; NCS showed predominantly demyelinating features; most patients received intravenous immunoglobulins (n=6) or glucocorticoids (n=5), but the outcome was variable; one patient was rechallenged with a different BRAFi/MEKi with a rapid relapse. Conclusion Patients under treatment with BRAFi/MEKi may develop treatment-induced PN. Two main phenotypes are seen: a symmetric, axonal, length-dependent polyneuropathy, and a demyelinating polyradiculoneuropathy. View on Web

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P12.13.B Investigating the tumor - immune cell crosstalk inex vivo glioblastoma models

alexandrossfakianakis shared this article with you from Inoreader P12.13.B Investigating the tumor - immune cell crosstalk inex vivo glioblastoma models via # Neuro-Oncology Current Issue Abstract Background Immunotherapy is a promising therapeutic approach to fight cancer by activating the immune system. Multiple immune-based strategies are under development that aim at recruiting or re-activating cellular components of the immune system. While immunotherapies have recently revolutionized cancer therapy, they have shown so far little therapeutic success in glioblastoma patients. To enhance the efficacy of novel strategies, we need to better understand the immunogenic status of glioblastoma cells and their cross-talk with immune cells in different microenvironmental niches. Material and Methods We assessed expression of molecules related to antigen processing and presentation as well as immune checkpoints in patient tumor databases as well as in a series of glioblastoma patient-derived organoids, 3D stem-like cultures and adherent cell lines under varying microenvironmental conditions (varying oxygen levels, inflammation ). We further established an allogenic co-culture protocol for glioblastoma organoids with immune cells isolated from HLA matched donor blood, allowing for the functional assessment of the crosstalk between tumor and immune cells. Results Analysis of a large cohort of patient tumors and patient-derived glioblastoma preclinical models shows inter-patient heterogeneity at the level of components of major histocompatibility complex (MHC)-MHC-II, immune checkpoints. Glioblastoma cells in general express MHC-I machinery, albeit at different levels. MHC-II and immune checkpoints are variably expressed across glioblastoma cells. Different tumor microenvironment conditions, including hypoxia and interferon-γ, impact the expression of immune-related molecules. Upon co-culture, HLA-matched donor-derived T cells integrate well into the core of glioblastoma tumor organoids and display reciprocal crosstalk with tumor cells. Conclusion Assessing antigen presentation and immune cell responses at the functional level are key to improve patient-specific responses to immunotherapies. Advanced glioblastoma organoids incorporating the immune compartment appear as clinically-relevant models for ex vivo efficacy studies. View on Web

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P12.10.A Supratentorial glioblastoma with spinal metastasis: a case report with molecular profiling

alexandrossfakianakis shared this article with you from Inoreader P12.10.A Supratentorial glioblastoma with spinal metastasis: a case report with molecular profiling via # Neuro-Oncology Current Issue Abstract Background Glioblastoma (GBM) is regarded as an aggressive brain tumor that rarely develops extracranial metastases. Despite well-investigated molecular alterations in GBM, there is a limited understanding of these associated with the metastatic potential of GBM. Material and Methods We present a case report of a 43-year-old woman with frontal GBM IDH-wildtype, who underwent gross-total resection followed by chemoradiation. Five months after surgery, the patient was diagnosed with an intraspinal GBM metastasis. Next-generation sequencing analysis of both primary and metastatic GBM tissues was performed using the Illumina TruSight Tumor 170 assay. Results The number of single nucleotide variants observed in the metastatic sample was more than 2-times higher. Mutations in TP53, PTEN, and RB1 found in the primary and metastatic tissue samples are indicative of the mesenchymal GBM subtype. Among others, in the metastatic s ample, there were detected two inactivating mutations (Arg1026Ile, Trp1831Ter) in the NF1 gene, two novel NOTCH3 variants of unknown significance predicted to be damaging (Pro1505Thr, Cys1099Tyr), one novel ARID1A variant of unknown significance (Arg1046Ser), and one gene fusion of unknown significance EIF2B5-KIF5B. Conclusion Based on the literature evidence, the inactivation of NF1, NOTCH3, and ARID1A could explain, at least in part, the acquired invasiveness and metastatic potential in this particular GBM case.This work was supported by the grant MUNI/A/1408/2021 of the Masaryk University, Brno, Czech Republic, and INTER-EXCELLENCE Programme / INTER-COST project no. LTC20027 of the Ministry of Health, Czech Republic. View on Web

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P05.03.B Application of rapid cytology in intraoperative diagnosis of primary central nervous system lymphoma

alexandrossfakianakis shared this article with you from Inoreader P05.03.B Application of rapid cytology in intraoperative diagnosis of primary central nervous system lymphoma via # Neuro-Oncology Current Issue Abstract Background To assesment the value of rapid cytological diagnosis in primary central nervous system lymphoma (PCNSL) surgery. Material and Methods A total of 213 PCNSL specimens from the First Affiliated Hospital of Fujian Medical University between 2012 to 2022 were included, 1-2mm3 was taken from the tissues diagnosed for intraoperative pathology and made into cell smears, rapid cytological diagnosis was performed after 95% ethanol fixation and H&E staining, most of the remaining tissues were diagnosed by frozen section. With the results of paraffin section pathological diagnosis as the control standard, compared the accuracy of rapid cytology and frozen tissue section and their combined diagnosis. Results Cytological smears can reveal microscopic structures within the cells under a microscope, furthermore, it can avoid the formation of artifacts or deformation of cells when frozen due to excessive wate r in brain tissue. Compared with paraffin section pathological diagnosis, the diagnostic accuracy of rapid cytology was 151cases (70.89%) , that of frozen tissue section was 175 cases (82.16%) , and that of the combination of the two methods was 187 cases (87.79%) . There were 26 cases (12.21%) in which neither method could give a definite conclusion intraoperatively and only depended on the results of paraffin tissue sections. Conclusion Rapid cytology alone is less accurate in diagnosing PCNSL than frozen sections alone. However, the combination of the two diagnosis can improve the accuracy of intraoperative diagnosis of PCNSL and correct some errors that may occur when only relying on frozen section diagnosis. It is especially suitable for stereotactic biopsy surgery or cases with very little tissue, as well as primary medical units without frozen section machine and other equipment. View on Web

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P11.31.B Pseudotumor Cerebri - a rare paraneoplastic manifestation

alexandrossfakianakis shared this article with you from Inoreader P11.31.B Pseudotumor Cerebri - a rare paraneoplastic manifestation via # Neuro-Oncology Current Issue Abstract Background Pseudotumor Cerebri (PC) is defined by an elevated intracranial pressure of unidentified cause, associated with normal cerebrospinal fluid (CSF) composition and no cause for hypertension on the neuroimaging evaluations. The symptoms described in association are headache, papilledema, changes in vision, and sometimes tinnitus. Its pathophysiology is far from being elucidated and the mechanisms proposed are multiple. There are some cases described in the literature in which PC is the first manifestation of a systemic neoplasm, most probably due to an abnormal response of the immune system to cancerous growth. We aim to emphasize a possible connection between adenocarcinoma of the lung and PC as the first paraneoplastic manifestation. Material and Methods We present the case of a 59-year-old patient, female, non-obese, who presented to the hospital for severe headache, blurred vision, tinnitus, and paresthesia on both h er upper limbs. On the first evaluation, the usual blood tests showed an increased creatinine level, and the subsequent abdominal echography and CT scan revealed bilateral ureter hydronephrosis, without an obvious obstacle, for which nephrostomies were implanted. On the ophthalmological evaluation bilateral papillary edema was described, although the cerebral CT with angiography and MRI showed no pathological modifications. A lumbar puncture with manometry was performed, that showed a CSF pressure of approximately 500 mmH2O. Results Following the clinical, imagistic, and biological manifestations, the diagnosis of PC was established. The decision to start the corticotherapy was made, followed by the addition of acetazolamide. Although the treatment tented was not efficient, the neurosurgery team decided that she is not a suitable candidate for a CSF shunting procedure and the ophthalmologist advised against an optic nerve sheath fenestration. The evolution was unfavorable, with the persistence of the symptoms. She underwent extensive investigations, the second cerebral MRI showing a slight dilation of the ventricles. On the thoracic-abdominal-pelvic CT, a pulmonary nodule with a malignant aspect was described, the histopathological results pleading for adenocarcinoma. The decision to excise the lesion was made, but after the surgery, the patient developed a cardiorespiratory arrest, without response to resuscitation. Conclusion Although there is scarce evidence of PC as a paraneoplastic syndrome, the evolution and investigations results support the possibility of a causal relationship. This is, to our knowledge, the second case of adenocarcinoma of the lung that primarily presents with PC. Further studies must be conducted to understand the underlying pathophysiology of this condition and to develop new treatment possibilities. View on Web

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P02.01.B The telomere maintenance mechanism spectrum and its dynamics in gliomas

alexandrossfakianakis shared this article with you from Inoreader P02.01.B The telomere maintenance mechanism spectrum and its dynamics in gliomas via # Neuro-Oncology Current Issue Abstract The activation of the telomere maintenance mechanism (TMM) is one of the critical drivers of cancer cell immortality. In gliomas, TERT expression and TERT promoter mutation are considered to reliably indicate telomerase activation, while ATRX mutation indicates alternative lengthening of telomeres (ALT). However, these relationships have not been extensively validated in tumor tissues. Here, we show through the direct measurement of telomerase activity and ALT in a large set of glioma samples that the TMM in glioma cannot be defined in the dichotomy of telomerase activity and ALT, regardless of TERT expression, TERT promoter mutation and ATRX mutation. Moreover, we observed that a considerable proportion of gli omas lack both telomerase activity and ALT (Neither group). And this Neither group exhibited evidence of slow growth potential. From a set of longitudinal samples from a separate cohort of glioma patients, we discovered that the TMM is not fixed but changes with glioma progression. Collectively, these results suggest that the TMM is a dynamic entity and that reflects the plasticity of the oncogenic biological status of tumor cells and that the TMM should be defined by the direct measurement of telomerase enzyme activity and evidence of ALT. View on Web

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P11.74.A Plexiform Neurofibromas prevalence and treatment modalities in a referral comprehensive cancer center

alexandrossfakianakis shared this article with you from Inoreader P11.74.A Plexiform Neurofibromas prevalence and treatment modalities in a referral comprehensive cancer center via # Neuro-Oncology Current Issue Abstract Background Neurofibromatosis type 1 (NF1) is the most common tumor predisposition syndrome, with an incidence of 1/3500. Plexiform neurofibromas (PN) are benign tumors that can occur along the nerve sheath throughout the body, with unpredictable growth and with risk of malignant transformation. Symptoms will depend on their size and location, and include pain, deformity and functional impairment. There is a great variability in the PN severity and impact on quality-of-life (QOL). An unknown percentage of NF1 patients may need treatment, either medical and/or surgical. Objectives To assess the frequency of PN in a NF1 population followed in a comprehensive cancer center. Material and Methods Retrospective study. All patients with NF1 and PN followed in our center, between 31/12/2000 and 31/12/2021. Results Of 438 NF1 patients, 185 had PN (42%). 52 NF1 patients with PN were children (≤ 18). The most common sym ptoms were pain in 71 people (38,4%), deformity in 70 (37,8%) and functional impairment in 69 (37,3%). Several patients had a combination of these symptoms. Different treatment modalities were used for PN: medical, surgical or both. In this study, 54 patients (29,1%) were treated with MEK inhibitors (selumetinib), 74 patients (40%) were treated surgically and 12,4% (23) needed a combined approach (medical and surgical treatment). Conclusion PN are frequent in NF1 patients. A significant percentage is symptomatic and will require treatment, surgical, medical or both. There is no standard of care for PN NF1. The timing and sequence of medical and surgical treatment is yet to be defined. View on Web

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OS08.7.A Lomustine and the immunocytokine L19TNF are a promising treatment combination for recurrent glioblastoma

alexandrossfakianakis shared this article with you from Inoreader OS08.7.A Lomustine and the immunocytokine L19TNF are a promising treatment combination for recurrent glioblastoma via # Neuro-Oncology Current Issue Abstract Background Treatment options for recurrent glioblastoma are limited and with the possible exception of regorafenib, no agent has demonstrated superior activity to lomustine. Therefore, there is an urgent need for more effective treatment strategies for recurrent glioblastoma. Here, we investigated different treatment combinations based on the tumor-stroma targeting antibody-cytokine fusion protein L19TNF in preclinical glioma models and translated the most effective treatment combination to patients with recurrent glioblastoma. Material and Methods Orthotopic immunocompetent mouse glioma models were used to study the anti-glioma activity of L19TNF in combination with anti-PD1, bevacizumab or lomustine. Tumor growth was monitored by MRI. Flow cytometry and microscopy were used to characterize tumor-infiltrating-immune cells. MHC immunoaffinity purification and mass spectrometry were used to characterize the MHC immunopeptidome. Genetic mouse models were used to study immune-dependent effects. Subsequently, we translated the most efficient treatment combination to patients with recurrent glioblastoma within a phase I/II clinical trial (NCT04573192). Results The combination of L19TNF and lomustine demonstrated strong synergistic anti-tumor activity in two immunocompetent orthotopic glioma models and cured a majority of tumor-bearing mice. In contrast, combinations with anti-PD-1 or bevacizumab had only limited anti-glioma activity. Furthermore, compared to the monotherapies, the combination of L19TNF and lomustine led to the strongest increase in tumor-infiltrating lymphoid cells as demonstrated by flow cytometry and microsopy and to the highest number of peptides presented in the context of MHC-I. The treatment effect was abrograted in different genetic immunodeficient mouse models. The treatment combination of L19TNF and lomustine was well tolerated in the first patients treated within a phase I/I I clinical trial and we observed partial tumor responses also in patients with an unmethylated MGMT promoter. Conclusion The combination of L19TNF and lomustine demonstrated promising anti-glioma activity and patients are currently recruited within a phase I/II clinical trial for patients with recurrent glioblastoma. View on Web

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