Prospective evaluation of flow-regulated valves for idiopathic normal pressure hydrocephalus: 1-year results

OBJECTIVE

Overdrainage and frequent reprogramming are common problems with programmable valves after ventriculoperitoneal shunt surgery for idiopathic normal pressure hydrocephalus (iNPH). Non-adjustable, flow-regulated valves offer a potential solution to these problems, but there is limited data on their efficacy. This study will evaluate neurological improvement and overdrainage rates within one year of treatment with a flow-regulated valve.

PATIENTS AND METHODS

This prospective study analyzes 45 iNPH patients (median age: 73 years) treated with a flow-regulated valve. Clinical evaluations were performed at baseline, postoperatively, and at 3, 6, and 12 months after surgery. The primary efficacy endpoint was improvement of at least 5 points on the iNPH grading scale at follow-up. The safety endpoint was radiographic evidence of overdrainage.

RESULTS

All patients presented with gait disturbance, 35 (78 %) had cognitive impairment, and 35 (78 %) had urinary incontinence. The median duration of symptoms was 24 months. The total iNPH score improved in 33/41 (81 %) at 3 months, in 29/34 (85 %) at 6 months, and in 22/29 (64 %) at 12 months. Overall, 40/45 (89 %) patients had a significant improvement on the iNPH scale. Secondary worsening of symptoms after initial improvement was observed in 5 (11 %) patients. Overdrainage occurred in one patient (2 %) requiring surgical evacuation.

CONCLUSION

Treatment of iNPH patients with flow-regulated valves resulted in a good neurological outcome with minimal rates of overdrainage. These results are encouraging and justify the clinical use of these valve types.

Sellar Melanoma With Lung Metastasis: A Case Report

We report the case of an 81-year-old patient with no pre-existing medical conditions who presented with a one-week history of progressive horizontal diplopia. Contrast-enhanced brain magnetic resonance imaging showed a heterogeneous sellar mass with the infiltration of the cavernous sinus and sella. Hormone levels were within normal limits. Considering an endocrine inactive pituitary adenoma, the patient underwent transsphenoidal resection. After surgery, the preoperative symptoms completely resolved. Histopathologic examination of the tumor specimen revealed melanoma. Since the patient had no history of cancer, an extensive staging workup was performed, which revealed multiple lung metastases. However, no primary tumor was found. We recommended adjuvant brain irradiation and chemo- and immunotherapy, but the patient refused further oncological treatment and died five months after surgery. Reported cases of sellar melanoma are rare, and the combination of sellar melanoma and lung metastasis without a cutaneous primary is unique. Although rare, malignant lesions of the sella must be considered in the differential diagnosis, especially in cases with rapid onset of symptoms.

Comparative Analysis of the Low-Profile Acclino Stent and the Enterprise Stent for the Treatment of Unruptured Intracranial Aneurysms

OBJECTIVE

In preliminary studies, advanced intracranial stents appear to have a favorable safety profile for intracranial aneurysm treatment. This dual-center study is a head-to-head comparison of the low-profile Acandis Acclino stent (a third-generation stent) and the first- and second-generation Enterprise stent.

METHODS

Patients who underwent stent-assisted coiling with either the Enterprise or the Acclino stent for unruptured aneurysms during an 8-year period were enrolled and compared for complications, clinical outcomes, and angiographic results. Primary outcome measures were ischemic stroke rate and mid-term complete occlusion rate. Propensity score adjustment was performed to account for small differences between the groups.

RESULTS

Enterprise and Acclino stents were used in 48 cases each. The overall rate of thrombotic complications was higher in the Enterprise group than in the Acclino group (20.8% vs. 4.2%, HR: 6.6, 95%CI: 2.2-20.0, P = 0.01, adjusted P < 0.01), which translated into a higher rate of major ischemic stroke after Enterprise treatment (6.3% vs. 0%, HR: 2.1, 95%CI: 1.8-2.4, P = 0.08, adjusted P < 0.01). Mid-term and long-term angiographic follow-up showed complete occlusion rates of 83.3% and 75.0% for Enterprise and 89.2% and 75.9% for Acclino (both P > 0.05). Retreatment rates were 10.4% in the Enterprise group and 4.2% in the Acclino group (P = 0.42, adjusted P = 0.10).

CONCLUSIONS

The results indicate a favorable safety profile of the Acclino over the Enterprise, justifying the use of advanced stent systems in clinical practice. However, further comparative studies of the Acclino and other competing stent systems are needed to draw a definitive conclusion on the state of stent-assisted coiling.

Cost-effectiveness of WEB Embolization, Coiling and Stent-assisted Coiling for the Treatment of Unruptured Intracranial Aneurysms

PURPOSE

Information about the cost-effectiveness of a certain treatment is relevant for decision-making and healthcare providers. This study compares the cost-effectiveness of the novel Woven Endobridge (WEB) for intracranial aneurysm treatment with conventional coiling and stent-assisted coiling (SAC) from the perspective of the German Statutory Health Insurance.

METHODS

A patient-level simulation was constructed to simulate 55-year-old patients with an unruptured middle cerebral artery aneurysm (size: 3-11 mm) considering WEB treatment, coiling or SAC in terms of morbidity, angiographic outcome, retreatment, procedural and rehabilitation costs and rupture rates. Incremental cost-effectiveness ratios (ICERs) were calculated as costs per quality-adjusted life years (QALYs) and costs per year with neurologic morbidity avoided. Uncertainty was explored with deterministic and probabilistic sensitivity analyses. The majority of data were obtained from prospective multi-center studies and meta-analyses of non-randomized studies.

RESULTS

In the base case, lifetime QALYs were 13.24 for the WEB, 12.92 for SAC and 12.68 for coiling. Lifetime costs were 20,440 € for the WEB, 23,167 € for SAC, and 8200 € for coiling. Compared to coiling, the ICER for the WEB was 21,826 €/QALY, while SAC was absolutely dominated by WEB. Probabilistic sensitivity analysis revealed that at a willingness-to-pay of ≥ 30,000 €/QALY, WEB was the preferred treatment. Deterministic sampling showed that the discount rate, material costs and retreatment rates had the largest impact on the ICERs.

CONCLUSION

The novel WEB showed at least comparable cost-effectiveness to SAC for treatment of broad-based unruptured aneurysms. Considering all three modalities, coiling had the least costs; however this modality is often not appropriate for the treatment of wide-necked aneurysms.

Super-enhancer hijacking drives ectopic expression of hedgehog pathway ligands in meningiomas

Hedgehog signaling mediates embryologic development of the central nervous system and other tissues and is frequently hijacked by neoplasia to facilitate uncontrolled cellular proliferation. Meningiomas, the most common primary brain tumor, exhibit Hedgehog signaling activation in 6.5% of cases, triggered by recurrent mutations in pathway mediators such as SMO. In this study, we find 35.6% of meningiomas that lack previously known drivers acquired various types of somatic structural variations affecting chromosomes 2q35 and 7q36.3. These cases exhibit ectopic expression of Hedgehog ligands, IHH and SHH, respectively, resulting in Hedgehog signaling activation. Recurrent tandem duplications involving IHH permit de novo chromatin interactions between super-enhancers within DIRC3 and a locus containing IHH. Our work expands the landscape of meningioma molecular drivers and demonstrates enhancer hijacking of Hedgehog ligands as a route to activate this pathway  in neoplasia.

Safety and efficacy of the fourth-generation Acandis Acclino flex plus stent for the treatment of complex intracranial aneurysms

OBJECTIVE

The low-profile Acandis Acclino flex plus (AFP) is a fourth-generation laser-cut microstent with a flexible structure designed for the treatment of a wide variety of aneurysms. We report our single-center experience with this device in the treatment of complex aneurysms.

METHODS

Twenty-eight patients were treated with the Acclino flex plus for 28 aneurysms. Aneurysm characteristics, technical success, complications, clinical outcome, and angiographic results were retrospectively analyzed.

RESULTS

The cohort included 8 unruptured untreated aneurysms, 9 unruptured recurrent aneurysms, and 12 ruptured aneurysms with aneurysm diameters ranging from 3 to 23 mm. The anterior communicating artery was the most common location (52%). Stent deployment was successful in 28 cases (97%) with an average of 1.3 stents per aneurysm. The overall procedural complication rate was 17%, including 2 (6.8%) major clinical events (one ischaemic stroke and one aneurysm perforation) and one (3.4%) minor clinical event (one seizure). Angiographic results of 23 aneurysms at a mean of 6 months were complete occlusion in 74%, neck remnants in 13% and aneurysm remnants in 13%. Three patients were retreated.

CONCLUSIONS

Given the complexity of the aneurysms, the use of the Acclino flex plus was feasible and associated with a favourable safety and efficacy profile. Further studies are needed to evaluate Acclino flex plus in other aneurysm subsets and to define its role in endovascular aneurysm treatment.

Angiographic characteristics associated with rupture of small intracranial aneurysms

OBJECTIVE

Contrary to previous assumptions, there is increasing evidence that small intracranial aneurysms carry a relevant risk of rupture. The aim of this study was to identify angiographic characteristics of small ruptured aneurysms ≤7 mm and to evaluate their significance for clinical decision making.

METHODS

A total of 385 patients with 149 unruptured and 236 ruptured intracranial aneurysms were retrospectively compared. Two- and three-dimensional digital subtraction angiography was used to determine aneurysm location, various size parameters, angulations, and morphology, as well as parent artery diameter.

RESULTS

Aneurysms of the anterior communicating artery, the posterior inferior cerebellar artery and the internal carotid artery terminus had a significantly increased prevalence among ruptured aneurysms. Ruptured aneurysms were characterized by a significantly larger aneurysm height (area-under-the curve [AUC] 0.60, p<0.01) and inclination angle (AUC 0.61, p=0.02) in addition to a smaller dome (AUC 0.44, p=0.02) and neck width (AUC 0.38, p<0.01). Calculation of size ratios increases the predictive value for aneurysm rupture, with AUC-values of 0.77 for aspect ratio (p<0.01) and 0.76 for size ratio (p<0.01). Aneurysm morphology was not a significant factor after multivariable adjustment (p=0.92). Arterial hypertension was the only clinical risk factor significantly associated with rupture (p<0.01).

CONCLUSIONS

Of the numerous factors associated with aneurysm rupture, we propose aneurysmal location, aspect ratio (cut-off: 1.5), and inclination angle as the most important morphological factors for assessing the rupture risk of small aneurysms because these factors have high AUC values and are robust to changes after rupture.

Intraoperative microscopic autofluorescence detection and characterization in brain tumors using stimulated Raman histology and two-photon fluorescence

Introduction

The intrinsic autofluorescence of biological tissues interferes with the detection of fluorophores administered for fluorescence guidance, an emerging auxiliary technique in oncological surgery. Yet, autofluorescence of the human brain and its neoplasia is sparsely examined. This study aims to assess autofluorescence of the brain and its neoplasia on a microscopic level by stimulated Raman histology (SRH) combined with two-photon fluorescence.

Methods

With this experimentally established label-free microscopy technique unprocessed tissue can be imaged and analyzed within minutes and the process is easily incorporated in the surgical workflow. In a prospective observational study, we analyzed 397 SRH and corresponding autofluorescence images of 162 samples from 81 consecutive patients that underwent brain tumor surgery. Small tissue samples were squashed on a slide for imaging. SRH and fluorescence images were acquired with a dual wavelength laser (790 nm and 1020 nm) for excitation. In these images tumor and non-tumor regions were identified by a convolutional neural network that reliably differentiates between tumor, healthy brain tissue and low quality SRH images. The identified areas were used to define regions.of- interests (ROIs) and the mean fluorescence intensity was measured.

Results

In healthy brain tissue, we found an increased mean autofluorescence signal in the gray (11.86, SD 2.61, n=29) compared to the white matter (5.99, SD 5.14, n=11, p<0.01) and in the cerebrum (11.83, SD 3.29, n=33) versus the cerebellum (2.82, SD 0.93, n=7, p<0.001), respectively. The signal of carcinoma metastases, meningiomas, gliomas and pituitary adenomas was significantly lower (each p<0.05) compared to the autofluorescence in the cerebrum and dura, and significantly higher (each p<0.05) compared to the cerebellum. Melanoma metastases were found to have a higher fluorescent signal (p<0.01) compared to cerebrum and cerebellum.

Discussion

In conclusion we found that autofluorescence in the brain varies depending on the tissue type and localization and differs significantly among various brain tumors. This needs to be considered for interpreting photon signal during fluorescence-guided brain tumor surgery.

Glioneuronal tumor with ATRX alteration, kinase fusion and anaplastic features (GTAKA): a molecularly distinct brain tumor type with recurrent NTRK gene fusions

Glioneuronal tumors are a heterogenous group of CNS neoplasms that can be challenging to accurately diagnose. Molecular methods are highly useful in classifying these tumors-distinguishing precise classes from their histological mimics and identifying previously unrecognized types of tumors. Using an unsupervised visualization approach of DNA methylation data, we identified a novel group of tumors (n = 20) that formed a cluster separate from all established CNS tumor types. Molecular analyses revealed ATRX alterations (in 16/16 cases by DNA sequencing and/or immunohistochemistry) as well as potentially targetable gene fusions involving receptor tyrosine-kinases (RTK; mostly NTRK1-3) in all of these tumors (16/16; 100%). In addition, copy number profiling showed homozygous deletions of CDKN2A/B in 55% of cases. Histological and immunohistochemical investigations revealed glioneuronal tumors with isomorphic, round and often condensed nuclei, perinuclear clearing, high mitotic activity and microvascular proliferation. Tumors were mainly located supratentorially (84%) and occurred in patients with a median age of 19 years. Survival data were limited (n = 18) but point towards a more aggressive biology as compared to other glioneuronal tumors (median progression-free survival 12.5 months). Given their molecular characteristics in addition to anaplastic features, we suggest the term glioneuronal tumor with ATRX alteration, kinase fusion and anaplastic features (GTAKA) to describe these tumors. In summary, our findings highlight a novel type of glioneuronal tumor driven by different RTK fusions accompanied by recurrent alterations in ATRX and homozygous deletions of CDKN2A/B. Targeted approaches such as NTRK inhibition might represent a therapeutic option for patients suffering from these tumors.

Impact of the SARS-CoV-2 pandemic on the survival of patients with high-grade glioma and best practice recommendations

The severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) has changed the clinical day-to-day practice. The aim of this study was to evaluate the impact of the pandemic on patients with high-grade glioma (HGG) as well as to derive best practice recommendations. We compared a multi-institutional cohort with HGG (n = 251) from 03/2020 to 05/2020 (n = 119) to a historical cohort from 03/2019 to 05/2019 (n = 132). The endpoints were outcome (progression-free survival (PFS) and overall survival (OS)) as well as patterns of care and time intervals between treatment steps. The median OS for WHO grade 4 gliomas was 12 months in 2019 (95% Confidence Interval 9.7-14.3 months), and not reached in 2020 (p = .026). There were no other significant differences in the Kaplan-Meier estimates for OS and PFS between cohorts of 2019 and 2020, neither did stratification by WHO grade reveal any significant differences for OS, PFS or for patterns of care. The time interval between cranial magnetic resonance imaging (cMRI) and biopsy was significantly longer in 2020 cohort (11 versus 21 days, p = .031). Median follow-up was 10 months (range 0-30 months). Despite necessary disease containment policies, it is crucial to ensure that patients with HGG are treated in line with the recent guidelines and standard of care (SOC) algorithms. Therefore, we strongly suggest pursuing no changes to SOC treatment, a timely diagnosis and treatment with short time intervals between first symptoms, initial diagnosis, and treatment, as well as a guideline-based cMRI follow-up.

Fight INflammation to Improve outcome after aneurysmal Subarachnoid HEmorRhage (FINISHER) trial: Study protocol for a randomized controlled trial

RATIONALE

Aneurysmal subarachnoid hemorrhage (SAH) has high morbidity and mortality. While the primary injury results from the initial bleeding cannot currently be influenced, secondary injury through vasospasm and delayed cerebral ischemia worsens outcome and might be a target for interventions to improve outcome. To date, beside the aneurysm treatment to prevent re-bleeding and the administration of oral nimodipine, there is no therapy available, so novel treatment concepts are needed. Evidence suggests that inflammation contributes to delayed cerebral ischemia and poor outcome in SAH. Some studies suggest a beneficial effect of anti-inflammatory glucocorticoids, but there are no data from randomized controlled trials examining the efficacy of glucocorticoids. Therefore, current guidelines do not recommend the use of glucocorticoids in SAH.

AIM

The Fight INflammation to Improve outcome after aneurysmal Subarachnoid HEmorRhage (FINISHER) trial aims to determine whether dexamethasone improves outcome in a clinically relevant endpoint in SAH patients.

METHODS AND DESIGN

FINISHER is a multicenter, prospective, randomized, double-blinded, placebo-controlled clinical phase III trial which is testing the outcome and safety of anti-inflammatory treatment with dexamethasone in SAH patients.

SAMPLE SIZE ESTIMATES

In all, 334 patients will be randomized to either dexamethasone or placebo within 48 h after SAH. The dexamethasone dose is 8 mg tds for days 1-7 and then 8 mg od for days 8-21.

STUDY OUTCOME

The primary outcome is the modified Rankin Scale (mRS) at 6 months, which is dichotomized to favorable (mRS 0-3) versus unfavorable (mRS 4-6).

DISCUSSION

The results of this study will provide the first phase III evidence as to whether dexamethasone improves outcome in SAH.

Initial clinical experience with N-hexyl cyanoacrylate for neuroendovascular embolization

OBJECTIVE

To report our initial clinical experience with N-hexyl cyanoacrylate (NHCA), a novel liquid agent for neurovascular embolization.

METHODS

Four paragangliomas were treated with percutaneous embolization using NHCA as the sole embolic material. In one dural arteriovenous fistula (dAVF), NHCA was used in combination with other embolic materials. Procedural specifics, complications and angiographic results were retrospectively evaluated.

RESULTS

Total or subtotal devascularization was obtained in 3 of the 4 paragangliomas. In the largest tumor, only partial devascularization could be achieved. The dAVF was completely occluded. Catheter entrapment did not occur. After dAVF treatment, the patient had an asymptomatic lacunar infarction, while there was no procedural morbidity related to paraganglioma treatment.

CONCLUSIONS

In this series, neurovascular embolization with NHCA was feasible and effective. It may be particularly beneficial for small and tortuous vessels that require low-profile catheterization and a slow and controlled polymerization. Further studies are necessary to prove the benefits of NHCA over established embolic agents.

Expression of ENO1 Is Up-regulated in Low-grade Glioma and Positively Correlated With Meningioma Grade

BACKGROUND

α-Enolase (ENO1) is a glycolytic enzyme involved in the Warburg effect which cancer cells utilize to satisfy their higher need for nutrients. Up-regulation of ENO1 has been detected in several tumor types, including melanoma and endometrial, gastric and colorectal cancer. In these tumors, ENO1 may function as prognostic marker. Therefore, it was our interest to determine the expression of ENO1 in glioma and meningioma and whether chemotherapy of glioma alters ENO1 expression.

MATERIAL AND METHODS

Tumor samples and control tissues were obtained during neurosurgery. All tumor samples were grouped according to WHO classification. Quantitative polymerase chain reaction and western blot were used to detect the expression of ENO1 in glioma and meningioma. All assays were carried out in triplicates; β-actin was used as a housekeeping gene. For western blots, all samples were incubated with mouse monoclonal anti-ENO1 followed by secondary horseradish peroxidase-linked anti-mouse antibody, with β-actin as a loading control. Immunofluorescence (n=33) was performed to determine the presence of ENO1 in tumor and control tissues using primary antibody to ENO1 and anti-Cy3 as secondary antibody.

RESULTS

The expression of ENO1 mRNA was significantly higher in the control group compared to glioma (p<0.0001) and its protein was also significantly up-regulated in low-grade glioma in comparison to high-grade (p<0.0001). ENO1 expression in grade II and III meningiomas was increased compared to grade I (p=0.016 and p=0.0010, respectively) and in grade III compared to grade II (p=0.0363).

CONCLUSION

Our findings suggest that ENO1 might be a marker for meningioma progression and that ENO1 is up-regulated in low-grade glioma.

Evaluation of 3-l- and 3-d-[18F]Fluorophenylalanines as PET Tracers for Tumor Imaging

Simple Summary

The early detection and treatment of malignant brain tumors can significantly improve the survival time and life quality of affected patients. Whereas positron emission tomography (PET) with O-(2-[¹⁸F]fluoroethyl)tyrosine ([¹⁸F]FET) offers improved diagnostic accuracy compared to other imaging methods, there is still a need for PET tracers with better tumor-specificity. A higher protein incorporation rate, as well as a higher affinity for the amino acid transporter LAT1, could provide probes with superior image quality compared to [¹⁸F]FET. The aim of the present study was a preclinical evaluation of the two enantiomeric phenylalanine (Phe) analogues, 3-l- and 3-d-[¹⁸F]fluorophenylalanine ([¹⁸F]FPhes), as possible alternatives to [¹⁸F]FET. Based on promising in vitro evaluation results, the radiolabeled amino acids were studied in vivo in two subcutaneous and one orthotopic rodent tumor xenograft models using µPET. The results show that 3-l- and 3-d-[¹⁸F]FPhe enable high-quality visualization of tumors with certain advantages over [¹⁸F]FET, making them promising candidates for further preclinical and clinical evaluations.

Abstract

Purpose: The preclinical evaluation of 3-l- and 3-d-[¹⁸F]FPhe in comparison to [¹⁸F]FET, an established tracer for tumor imaging. Methods: In vitro studies were conducted with MCF-7, PC-3, and U87 MG human tumor cell lines. In vivo µPET studies were conducted in healthy rats with/without the inhibition of peripheral aromatic l-amino acid decarboxylase by benserazide pretreatment (n = 3 each), in mice bearing subcutaneous MCF-7 or PC-3 tumor xenografts (n = 10), and in rats bearing orthotopic U87 MG tumor xenografts (n = 14). Tracer accumulation was quantified by SUV_max, SUV_mean and tumor-to-brain ratios (TBrR). Results: The uptake of 3-l-[¹⁸F]FPhe in MCF-7 and PC-3 cells was significantly higher relative to [¹⁸F]FET. The uptake of all three tracers was significantly reduced by the suppression of amino acid transport systems L or ASC. 3-l-[¹⁸F]FPhe but not 3-d-[¹⁸F]FPhe exhibited protein incorporation. In benserazide-treated healthy rats, brain uptake after 42–120 min was significantly higher for 3-d-[¹⁸F]FPhe vs. 3-l-[¹⁸F]FPhe. [¹⁸F]FET showed significantly higher uptake into subcutaneous MCF-7 tumors (52–60 min p.i.), while early uptake into orthotopic U87 MG tumors was significantly higher for 3-l-[¹⁸F]FPhe (SUV_max: 3-l-[¹⁸F]FPhe, 107.6 ± 11.3; 3-d-[¹⁸F]FPhe, 86.0 ± 4.3; [¹⁸F]FET, 90.2 ± 7.7). Increased tumoral expression of LAT1 and ASCT2 was confirmed immunohistologically. Conclusion: Both novel tracers enable accurate tumor delineation with an imaging quality comparable to [¹⁸F]FET.

BIOM-01. MTH1 EXPRESSION IS UPREGULATED IN BRAIN METASTASES OF MALIGNANT MELANOMA

MuT Homolog1 (MTH1) is an enzyme involved in DNA repair in normal cells and is often up-regulated in cancer cells. The enzyme catalyses the hydrolysis of oxidised dNTPs, to prevent their incorporation into DNA or RNA, resulting in mutations or cell damage/death. Cancer cells can have a high concentration of ROS, due to defective redox regulation. This results in the damage of DNA and oxidises free dNTPS, which in turn leads to mutations in DNA replication or cell death. The quantification of MTH1 expression was done by Western Blot analysis. 16 tumours were obtained during neurosurgery, 8 metastatic and 8 recurrent tumours of the same patient, and immediately frozen using liquid nitrogen. The proteins were extracted using RIPA lysis buffer. Western Blot was performed and detection followed via peroxidase linked secondary antibodies. MTH1 expression was shown to be up-regulated in brain metastases (1,442+/-0,6374) versus normal brain tissue (0,4133+/-0,277). However, in the recurrent tumour of the brain metastases, MTH1 was not expressed in a significantly higher amount compared the control tissue and less than in the brain metastases (0,6941+/-0,4146). The high expression of MTH1 in cerebral metastases presents a therapeutic target for MTH1-inhibitors, provided these are able to cross the blood brain barrier. Comparison to the primary melanoma tumour would be useful in showing significant differences of the metastases. Lower levels of MTH1 in recurrent brain metastases may suggest dedifferentiation from the original metastases. It may present a target for specific treatment of brain metastases of melanoma.

BSCI-13. MTH1 expression is upregulated in brain metastases of malignant melanoma

Objective

MuT Homolog1 (MTH1) is an enzyme involved in DNA repair in normal cells and is often up- regulated in cancer cells. The enzyme catalyses the hydrolysis of oxidised dNTPs, to prevent their incorporation into DNA or RNA, resulting in mutations or cell damage/death. Cancer cells can have a high concentration of ROS, due to defective redox regulation. This results in the damage of DNA and oxidises free dNTPS, which in turn leads to mutations in DNA replication or cell death. Identifying MTH1 in brain metastases could present a target for treatment with MTH1-Inhibitors.

Methods

The quantification of MTH1 expression was shown using Western Blot analysis. 16 tumours were obtained during neurosurgery, 8 metastatic and 8 recurrent tumours of the same patient, and immediately frozen using liquid nitrogen. The proteins were extracted using RIPA lysis buffer. Western Blot was performed and detection followed via peroxidase linked secondary antibodies.

Results

MTH1 expression was shown to be up-regulated in brain metastases (1,442+/-0,6374) versus normal brain tissue (0,4133+/-0,277). However, in the recurrent tumour of the brain metastases, MTH1 was not expressed in a significantly higher amount compared the controll tissue and less than in the brain metastases (0,6941+/-0,4146).

Conclusion

The high expression of MTH1 in cerebral metastases is not uncommon for many cancers and thus presents a therapeutic target for MTH1-inhibitors, provided these are able to cross the blood brain barrier. Comparison to the primary melanoma tumour would be useful in showing significant differences of the metastases. Lower levels of MTH1 in recurrent brain metastases may suggest dedifferentiation from the original metastases. It may present a target for specific treatment of brain metastases of melanoma.

Clinical Characteristics and Magnetic Resonance Imaging-Based Prediction of the KLF4K409Q Mutation in Meningioma

BACKGROUND

Meningioma is the most common primary brain tumor in adults. In recent years, several non-neurofibromin 2 mutations, i.e., AKT1, SMO, TRAF7, and KLF4 mutations, specific for meningioma have been identified. This study aims to analyze the clinical impact and imaging characteristics of the KLF4^K409Q mutation in meningioma.

METHODS

Clinical, neuropathologic, and imaging data of 170 patients who underwent meningioma resection between 2013 and 2018 were retrospectively collected and tumors were analyzed for the presence of the KLF4^K409Q mutation. We collected imaging characteristics, performed volumetric analysis of tumor size and peritumoral edema (PTBE), and calculated the edema index (EI, i.e., ratio of PTBE to tumor volume). Receiver operating characteristic curve analysis was performed to identify cut-off EI values to predict the mutational status of KLF4.

RESULTS

Eighteen (10.6%) of the meningiomas carried the KLF4^K409Q mutation; these were significantly associated with a secretory subtype (P < 0.001) and sphenoid wing location (P = 0.029). Smaller tumor size (P = 0.007), an increased PTBE (P = 0.012), and an increased EI (P = 0.001) proved to be significantly associated with the KLF4^K409Q mutation. In receiver operating characteristic curve analysis, EI predicted the KLF4^K409Q mutation with an area under the curve of 0.728 (P = 0.0016).

CONCLUSIONS

The KLF4^K409Q mutation is associated with a distinct small tumor subtype, prone to substantial PTBE. EI is a reliable parameter to predict the KLF4^K409Q mutation in meningioma, thus providing a tool for improvement of pre- and perioperative medical management.

Abstract 2164: Overexpression of the TERT binding proteins GABPA/B in Glioblastoma

Enhanced expression of TERT in gliomas is a result of two hotspot mutations, C228T and C250T, at the promoter region. GA-binding proteins selectively bind at these positions, respectively causing an activation of the promoter and overexpression of TERT. GABP is a multimeric protein consisting of GABPA and GABPB with its isoforms GABPB1, GABPB1-L, GABPB1-S, GABPB2. In this study, we investigated the mRNA expression and association between TERT and GABPA/B isoforms in tumor samples of different glioma grades. The expression was determined by quantitative real-time PCR and the results were statistically analyzed. We present that TERT is mainly expressed in primary glioblastomas. All GA-binding proteins progress through the glioma grades and have the highest expression levels in secondary glioblastomas. In secondary glioblastomas after chemotherapy, GABPB1 and GABPB1-L are lower expressed than without treatment. In high grades, TERT and GABPA, GAPB1, GABPB1-L, GABPB1-S are upregulated compared to low grades. Between primary and secondary glioblastomas with and without chemotherapy, TERT is elevated in the former while GABPB1 is increased in the secondary glioblastomas. GABPA and GABPB1, GABPB1-L and GABPB1-S positive correlate in primary glioblastomas. The present study confirms the upregulation of TERT in primary glioblastomas while all GABP proteins rise with the malignancy of the gliomas. TERT and all GABP proteins seem to play a key role in the gliomagenesis.

Citation Format: Marco Timmer, Efthymios Papazacharias, Roland Goldbrunner. Overexpression of the TERT binding proteins GABPA/B in Glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2164.

TERT and its binding protein: overexpression of GABPA/B in high grade gliomas

Enhanced expression of TERT in gliomas is a result of two hotspot mutations, C228T and C250T, at the promoter region. GA-binding proteins selectively bind at these positions, respectively, causing an activation of the promoter and overexpression of TERT. GABP is a multimeric protein consisting of GABPA and GABPB with its isoforms GABPB1, GABPB1-L, GABPB1-S, GABPB2. In this study, we investigated the mRNA expression and association between TERT and GABPA/B isoforms in tumor samples of different glioma grades. The expression was determined by quantitative real-time PCR and the results were statistically analyzed. We present that TERT is mainly expressed in primary glioblastomas. All GA-binding proteins progress through the glioma grades and have the highest expression levels in secondary glioblastomas. In secondary glioblastomas after chemotherapy, GABPB1 and GABPB1-L are expressed on a lower level than without treatment. In high grades, TERT and GABPA, GAPB1, GABPB1-L, GABPB1-S are upregulated compared to low grades. Between primary and secondary glioblastomas with and without chemotherapy, TERT is elevated in the former while GABPB1 is increased in the secondary glioblastomas. GABPA and GABPB1, GABPB1-L and GABPB1-S positive correlate in primary glioblastomas. The present study confirms the upregulation of TERT in primary glioblastomas while all GABP proteins rise with the malignancy of the gliomas. Further investigations must be made to elucidate the relation between TERT and all GABP proteins as it may play a key role in the gliomagenesis.

Impact of aneurysm morphology on aneurysmal subarachnoid hemorrhage severity, cerebral infarction and functional outcome

OBJECTIVE

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with high morbidity. The objective was to evaluate, whether specific morphological aneurysm characteristics could serve as predictive values for aSAH severity, disease-related complications and clinical outcome.

METHODS

A total of 453 aSAH patients (mean age: 54.9 ± 13.8 years, mean aneurysm size: 7.5 ± 3.6 mm) treated at a single center were retrospectively included. A morphometric analysis was performed based on angiographic image sets, determining aneurysm location, aneurysm size, neck width, aneurysm size ratios, aneurysm morphology and vessel size. The following outcome measures were defined: World Federation of Neurosurgical Societies (WFNS) grade 4 and 5, Fisher grade 4, vasospasm, cerebral infarction and unfavorable functional outcome.

RESULTS

Regarding morphology parameters, aneurysm neck width was an independent predictor for Fisher 4 hemorrhage (OR: 1.1, 95%CI: 1.0-1.3, p = 0.048), while dome width (OR: 0.92, 95%CI: 0.86-0.97, p = 0.005) and internal carotid artery location (OR: 2.1, 95%CI: 1.1-4.2, p = 0.028) predicted vasospasm. None of the analyzed morphological characteristics prognosticated functional outcome. Patient age (OR: 0.95, 95%CI: 0.93-0.96, p < 0.001), WFNS score (OR: 4.8, 95%CI: 2.9-8.0, p < 0.001), Fisher score (OR: 2.3, 95%CI: 1.4-3.7, p < 0.001) and cerebral infarction (OR: 4.5, 95%CI: 2.7-7.8, p < 0.001) were independently associated with unfavorable outcome.

CONCLUSIONS

The findings indicate a correlation between aneurysm morphology, Fisher grade and vasospasm. Further studies will be required to reveal an independent association of aneurysm morphology with cerebral infarction and functional outcome.

Woven Endobridge Embolization Versus Microsurgical Clipping for Unruptured Anterior Circulation Aneurysms: A Propensity Score Analysis

BACKGROUND

Intrasaccular flow-disruption represents a new paradigm in endovascular treatment of wide-necked bifurcation aneurysms.

OBJECTIVE

To retrospectively compare Woven Endobridge (WEB) embolization with microsurgical clipping for unruptured anterior circulation aneurysms using propensity score adjustment.

METHODS

A total of 63 patients treated with WEB and 103 patients treated with clipping were compared based on the intention-to-treat principle. The primary outcome measures were immediate technical treatment success, major adverse events, and 6-mo complete aneurysm occlusion.

RESULTS

The technical success rates were 83% for WEB and 100% for clipping. Procedure-related complications occurred more often in the clipping group (13%) than the WEB group (6%, adjusted P < .01). However, the rates of major adverse events were comparable in both groups (WEB: 3%, clip: 4%, adjusted P = .53). At the 6-mo follow-up, favorable functional outcomes were achieved in 98% of the WEB embolization group and 99% of the clipping group (adjusted P = .19). Six-month complete aneurysm occlusion was obtained in 75% of the WEB group and 94% of the clipping group (adjusted P < .01).

CONCLUSION

Microsurgical clipping was associated with higher technical success and complete occlusion rates, whereas WEB had a lower complication rate. Favorable functional outcomes were achieved in ≥98% of both groups. The decision to use a specific treatment modality should be made on an individual basis and in accordance with the patient's preferences.

Impact of the weekend effect on outcome after microsurgical clipping of ruptured intracranial aneurysms

BACKGROUND

The "weekend effect" describes the assumption that weekend and/or on-call duty admission of emergency patients is associated with increased morbidity and mortality rates. For aneurysmal subarachnoid hemorrhage, we investigated, whether presentation out of regular working hours and microsurgical clipping at nighttime correlates with worse patient outcome.

METHODS

This is a retrospective review of consecutive patients that underwent microsurgical clipping of an acutely ruptured aneurysm at our institution between 2010 and 2019. Patients admitted during (1) regular working hours (Monday-Friday, 08:00-17:59) and (2) on-call duty and microsurgical clipping performed during (a) daytime (Monday-Sunday, 08:00-17:59) and (b) nighttime were compared regarding the following outcome parameters: operation time, treatment-related complications, vasospasm, functional outcome, and angiographic results.

RESULTS

Among 157 enrolled patients, 104 patients (66.2%) were admitted during on-call duty and 48 operations (30.6%) were performed at nighttime. Admission out of regular hours did not affect cerebral infarction (p = 0.545), mortality (p = 0.343), functional outcome (p = 0.178), and aneurysm occlusion (p = 0.689). Microsurgical clipping at nighttime carried higher odds of unfavorable outcome at discharge (OR: 2.3, 95%CI: 1.0-5.1, p = 0.039); however, there were no significant differences regarding the remaining outcome parameters. After multivariable adjustment, clipping at nighttime did not remain as independent prognosticator of short-term outcome (OR: 2.1, 95%CI: 0.7-6.2, p = 0.169).

CONCLUSIONS

Admission out of regular working hours and clipping at nighttime were not independently associated with poor outcome. The adherence to standardized treatment protocols might mitigate the "weekend effect."

Microsurgical Clipping versus Advanced Endovascular Treatment of Unruptured Middle Cerebral Artery Bifurcation Aneurysms After a "Coil-First" Policy

OBJECTIVE

Although intracranial aneurysms are increasingly treated endovascularly, microsurgical clipping has been the standard approach for middle cerebral artery (MCA) aneurysms. We compared microsurgical clipping and state-of-the-art endovascular treatment of unruptured MCA bifurcation aneurysms treated at a neurovascular center following a "coil-first" policy.

METHODS

This single-center study included 148 patients treated for 160 unruptured MCA bifurcation aneurysms. Technical success, complications, clinical outcome, and angiographic results were retrospectively compared.

RESULTS

Microsurgical clipping was performed for 120 MCA aneurysms (75%) and endovascular treatment for 40 (25%; conventional coiling: 8, stent-assisted coiling: 16, balloon-assisted coiling: 3, and flow-disruption: 13). Technical treatment success was higher in the clipping group (100%) than in the endovascular group (92.5%, P = 0.015). Overall, complications occurred in 16.7% for clipping and in 20.0% for endovascular treatment (P = 0.631). Major ischemic stroke rates were 4.2% in the clipping group and 7.5% in the endovascular group (P = 0.414). At 6 months, a favorable outcome was obtained by 99.2% after clipping and 95.0% after endovascular treatment (P = 0.154). The 6-month complete aneurysm occlusion rates were by trend higher in the clipping group (89.2%) than in the endovascular group (75.9%, P = 0.078).

CONCLUSIONS

Microsurgical clipping was associated with a higher technical success rate and tendentially higher complete occlusion than endovascular treatment, with no additional morbidity and similar clinical outcome. On the basis of these results, clipping proves to be the standard treatment option for MCA bifurcation aneurysms. However, endovascular treatment represents a safe and efficient alternative treatment option for patients.

Impact of Obesity on Complication Rates, Clinical Outcomes, and Quality of Life after Minimally Invasive Transforaminal Lumbar Interbody Fusion

BACKGROUND

 Percutaneous pedicle screw fixation in obese patients remains a surgical challenge. We aimed to compare patient-reported outcomes and complication rates between obese and nonobese patients who were treated by minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).

METHODS

 The authors retrospectively reviewed patients who underwent MIS-TLIF at a single institution between 2011 and 2014. Patients were classified as obese (body mass index [BMI] ≥30 kg/m²) or nonobese (BMI < 30 kg/m²), according to their BMI. Outcomes assessed were complications, numerical rating scale (NRS) scores for back and leg pain, Oswestry Disability Index (ODI), and 36-Item Short-Form Survey (SF-36) scores.

RESULTS

 The final study group consisted of 71 patients, 24 obese (33.8%, 34.8 ± 3.8 kg/m²) and 47 nonobese (66.2%, 25.4 ± 2.9 kg/m²). Instrumentation failures (13.6 vs. 17.0%), dural tears (17.2 vs. 4.0%), and revision rates (16.7 vs. 19.1%) were similar between both groups (p > 0.05). Perioperative improvements in back pain (4.3 vs. 5.4, p = 0.07), leg pain (3.8 vs. 4.2, p = 0.6), and ODI (13.3 vs. 22.5, p = 0.5) were comparable among the groups and persisted at long-term follow-up. Obese patients had worse postoperative physical component SF-36 scores than nonobese patients (36.4 vs. 42.7, p = 0.03), while the mental component scores were not statistically different (p = 0.09).

CONCLUSION

 Obese patients can achieve similar improvement of the pain intensity and functional status even at long-term follow-up. In patients with appropriate surgical indications, obesity should not be considered a contraindication for MIS-TLIF surgery.

Acquisition of chromosome 1q duplication in parental and genome-edited human-induced pluripotent stem cell-derived neural stem cells results in their higher proliferation rate in vitro and in vivo

Objectives

Genetic engineering of human‐induced pluripotent stem cell‐derived neural stem cells (hiPSC‐NSC) may increase the risk of genomic aberrations. Therefore, we asked whether genetic modification of hiPSC‐NSCs exacerbates chromosomal abnormalities that may occur during passaging and whether they may cause any functional perturbations in NSCs in vitro and in vivo.

Materials and Methods

The transgenic cassette was inserted into the AAVS1 locus, and the genetic integrity of zinc‐finger nuclease (ZFN)‐modified hiPSC‐NSCs was assessed by the SNP‐based karyotyping. The hiPSC‐NSC proliferation was assessed in vitro by the EdU incorporation assay and in vivo by staining of brain slices with Ki‐67 antibody at 2 and 8 weeks after transplantation of ZFN‐NSCs with and without chromosomal aberration into the striatum of immunodeficient rats.

Results

During early passages, no chromosomal abnormalities were detected in unmodified or ZFN‐modified hiPSC‐NSCs. However, at higher passages both cell populations acquired duplication of the entire long arm of chromosome 1, dup(1)q. ZNF‐NSCs carrying dup(1)q exhibited higher proliferation rate than karyotypically intact cells, which was partly mediated by increased expression of AKT3 located on Chr1q. Compared to karyotypically normal ZNF‐NSCs, cells with dup(1)q also exhibited increased proliferation in vivo 2 weeks, but not 2 months, after transplantation.

Conclusions

These results demonstrate that, independently of ZFN‐editing, hiPSC‐NSCs have a propensity for acquiring dup(1)q and this aberration results in increased proliferation which might compromise downstream hiPSC‐NSC applications.

Impact of aneurysm shape and neck configuration on cerebral infarction during microsurgical clipping of intracranial aneurysms

OBJECTIVE

Cerebral infarction is a significant cause of morbidity and mortality related to microsurgical clipping of intracranial aneurysms. The objective of this study was to determine the impact of aneurysm shape and neck configuration on cerebral infarction after aneurysm surgery.

METHODS

The authors retrospectively reviewed consecutive cases of ruptured and unruptured aneurysms treated with microsurgical clipping at their institution between 2010 and 2018. Three-dimensional reconstructions from preoperative computed tomography and digital subtraction angiography were used to determine aneurysm shape (regular/complex) and neck configuration (regular/irregular). Morphological and procedure-related risk factors for cerebral infarction were identified using univariate and multivariate statistical analyses.

RESULTS

Among 243 patients with 252 aneurysms (148 ruptured, 104 unruptured), the overall cerebral infarction rate was 17.1%. Infarction tended to occur more often in aneurysms with complex shape (p = 0.084). Likewise, aneurysms with an irregular neck had a significantly higher rate of infarction (37.5%) than aneurysms with regular neck configuration (10.1%, p < 0.001). Aneurysms with an irregular neck were associated with a higher rate of intraoperative rupture (p = 0.003) and temporary parent artery occlusion (p = 0.037). In the multivariate analysis, irregular neck configuration was identified as an independent risk factor for infarction (OR 4.2, 95% CI 1.9-9.4, p < 0.001), whereas the association between aneurysm shape and infarction was not significant (p = 0.966).

CONCLUSIONS

Irregular aneurysm neck configuration represents an independent risk factor for cerebral infarction during microsurgical clipping of both ruptured and unruptured aneurysms.

Delayed hospital admission of patients with aneurysmal subarachnoid hemorrhage: clinical presentation, treatment strategies, and outcome

OBJECTIVE

Timely aneurysm occlusion and neurointensive care treatment are key principles in the management of aneurysmal subarachnoid hemorrhage (aSAH) to prevent secondary brain injury. Patients with early (EHA) and delayed hospital admission (DHA) were compared in terms of clinical presentation, treatment strategies, aSAH-related complications, and outcome.

METHODS

In this retrospective study, consecutive aSAH patients were treated at a single neurovascular center between 2009 and 2019. Propensity score matching was performed to account for divergent baseline characteristics.

RESULTS

Among 509 included patients, 55 were admitted more than 48 hours after ictus (DHA group). DHA patients were significantly younger (52 ± 11 vs 56 ± 14 years, p = 0.03) and had lower World Federation of Neurosurgical Societies scores (p < 0.01) than EHA patients. In 54.5% of the cases, DHA patients presented with neurological deterioration or aggravated symptoms. Propensity score matching revealed a higher vasospastic infarction rate in the DHA group (41.5%) than in the EHA group (22.6%) (p = 0.04). A similar portion of patients in both groups achieved favorable outcome at midterm follow-up (77.3% vs 73.6%, p = 0.87). DHA patients (62.3%) received conventional coiling more often than EHA patients (41.5%) (p = 0.03).

CONCLUSIONS

DHA patients are at an increased risk of cerebral infarction. Nevertheless, state-of-the-art neurointensive care treatment can result in a good clinical outcome.

KLF4K409Q-mutated meningiomas show enhanced hypoxia signaling and respond to mTORC1 inhibitor treatment

Meningioma represents the most common primary brain tumor in adults. Recently several non-NF2 mutations in meningioma have been identified and correlated with certain pathological subtypes, locations and clinical observations. Alterations of cellular pathways due to these mutations, however, have largely remained elusive. Here we report that the Krueppel like factor 4 (KLF4)-K409Q mutation in skull base meningiomas triggers a distinct tumor phenotype. Transcriptomic analysis of 17 meningioma samples revealed that KLF4^K409Q mutated tumors harbor an upregulation of hypoxia dependent pathways. Detailed in vitro investigation further showed that the KLF4^K409Q mutation induces HIF-1α through the reduction of prolyl hydroxylase activity and causes an upregulation of downstream HIF-1α targets. Finally, we demonstrate that KLF4^K409Q mutated tumors are susceptible to mTOR inhibition by Temsirolimus. Taken together, our data link the KLF4^K409Q mediated upregulation of HIF pathways to the clinical and biological characteristics of these skull base meningiomas possibly opening new therapeutic avenues for this distinct meningioma subtype.

Single-Step Resection of Sphenoorbital Meningiomas and Orbital Reconstruction Using Customized CAD/CAM Implants

Objective  Computer-aided design and manufacturing (CAD/CAM) implants are fabricated based on volumetric analysis of computed tomography (CT) scans and are routinely used for the reconstruction of orbital fractures. We present three cases of patients with sphenoorbital meningiomas that underwent tumor resection, orbital decompression, and orbital reconstruction with patient specific porous titanium or acrylic implants in a single procedure. Methods  The extent of bone resection of the sphenoorbital meningiomas was planned in a virtual three-dimensional (3D) environment using preoperative thin-layer CT data. The anatomy of the orbital wall in the resection area was reconstructed by superimposing the contralateral unaffected orbit and by using the information of the neighboring bony structures. The customized implants and a corresponding craniotomy template were designed in the desired size and shape by the manufacturer. Results  All patients presented with a sphenoorbital meningioma and exophthalmos. After osteoclastic craniotomy with the drilling template, orbital decompression was performed. Implant fitting was tight in two cases and could be easily fixated with miniplates and screws. In the third patient, a reoperation was necessary for additional bone resection, as well as drilling and repositioning of the implant. The postoperative CT scans showed an accurate reconstruction of the orbital wall. After surgery, exophthalmos was substantially reduced and a satisfying cosmetic result could be finally achieved in all patients. Conclusions  The concept of preoperative 3D virtual treatment planning and single-step orbital reconstruction with CAD/CAM implants after tumor resection involving the orbit is well feasible and can lead to good cosmetic results.

Automated Meningioma Segmentation in Multiparametric MRI : Comparable Effectiveness of a Deep Learning Model and Manual Segmentation

PURPOSE

Volumetric assessment of meningiomas represents a valuable tool for treatment planning and evaluation of tumor growth as it enables a more precise assessment of tumor size than conventional diameter methods. This study established a dedicated meningioma deep learning model based on routine magnetic resonance imaging (MRI) data and evaluated its performance for automated tumor segmentation.

METHODS

The MRI datasets included T1-weighted/T2-weighted, T1-weighted contrast-enhanced (T1CE) and FLAIR of 126 patients with intracranial meningiomas (grade I: 97, grade II: 29). For automated segmentation, an established deep learning model architecture (3D deep convolutional neural network, DeepMedic, BioMedIA) operating on all four MR sequences was used. Segmentation included the following two components: (i) contrast-enhancing tumor volume in T1CE and (ii) total lesion volume (union of lesion volume in T1CE and FLAIR, including solid tumor parts and surrounding edema). Preprocessing of imaging data included registration, skull stripping, resampling, and normalization. After training of the deep learning model using manual segmentations by 2 independent readers from 70 patients (training group), the algorithm was evaluated on 56 patients (validation group) by comparing automated to ground truth manual segmentations, which were performed by 2 experienced readers in consensus.

RESULTS

Of the 56 meningiomas in the validation group 55 were detected by the deep learning model. In these patients the comparison of the deep learning model and manual segmentations revealed average dice coefficients of 0.91 ± 0.08 for contrast-enhancing tumor volume and 0.82 ± 0.12 for total lesion volume. In the training group, interreader variabilities of the 2 manual readers were 0.92 ± 0.07 for contrast-enhancing tumor and 0.88 ± 0.05 for total lesion volume.

CONCLUSION

Deep learning-based automated segmentation yielded high segmentation accuracy, comparable to manual interreader variability.

CBMT-25. THE KLF4K409Q MUTATION IN MENINGIOMA IMPAIRS HIF-1Α DEGRADATION AND CAN BE HARNESSED FOR TARGETED THERAPY

Recently, several Non-NF2 driver mutations (KLF4, TRAF7, SMO, AKT1E17K) in meningioma have been identified. While they have been shown to correlate with certain pathological subtypes and locations, the clinical impact and repercussions on cellular pathways have largely remained elusive. Through analysis of clinical, pathological and preoperative imaging data of 96 patients and sequencing of the corresponding 96 tumor samples for the Krueppel like factor 4-K409Q mutation (KLF4K409Q) we present evidence that the KLF4K409Q tumors harbour an increased risk for peritumoral brain edema (PTBE) and can be predicted with the edema-index, a simple tool based on preoperative imaging. Further analysis involving RNA-sequencing of a matched subset of 7 KLF4K409Q and 10 KLF4-wildtype (wt) tumors revealed a significant shift of gene expression and the upregulation of hypoxia driven pathways, including VEGF levels, in KLF4K409Q tumors. On the cellular level, we go on to show that the KLF4K409Q mutation results in an increased KLF-4 stability as well as the inhibition of hydroxylation dependent degradation of HIF1-α and a significant increase of VEGF expression under hypoxic conditions. Finally, we demonstrate that this upregulation of VEGF in KLF4K409Q cells can be inhibited by targeting the mammalian target of rapamycin (mTor) with Temsirolimus. In summary we show that the KLF4K409Q mutation in meningioma has highly relevant repercussions in both, the biological and clinical context and can be harnessed for targeted therapy.

Correlations between genomic subgroup and clinical features in a cohort of more than 3000 meningiomas

OBJECTIVE

Recent large-cohort sequencing studies have investigated the genomic landscape of meningiomas, identifying somatic coding alterations in NF2, SMARCB1, SMARCE1, TRAF7, KLF4, POLR2A, BAP1, and members of the PI3K and Hedgehog signaling pathways. Initial associations between clinical features and genomic subgroups have been described, including location, grade, and histology. However, further investigation using an expanded collection of samples is needed to confirm previous findings, as well as elucidate relationships not evident in smaller discovery cohorts.

METHODS

Targeted sequencing of established meningioma driver genes was performed on a multiinstitution cohort of 3016 meningiomas for classification into mutually exclusive subgroups. Relevant clinical information was collected for all available cases and correlated with genomic subgroup. Nominal variables were analyzed using Fisher's exact tests, while ordinal and continuous variables were assessed using Kruskal-Wallis and 1-way ANOVA tests, respectively. Machine-learning approaches were used to predict genomic subgroup based on noninvasive clinical features.

RESULTS

Genomic subgroups were strongly associated with tumor locations, including correlation of HH tumors with midline location, and non-NF2 tumors in anterior skull base regions. NF2 meningiomas were significantly enriched in male patients, while KLF4 and POLR2A mutations were associated with female sex. Among histologies, the results confirmed previously identified relationships, and observed enrichment of microcystic features among "mutation unknown" samples. Additionally, KLF4-mutant meningiomas were associated with larger peritumoral brain edema, while SMARCB1 cases exhibited elevated Ki-67 index. Machine-learning methods revealed that observable, noninvasive patient features were largely predictive of each tumor's underlying driver mutation.

CONCLUSIONS

Using a rigorous and comprehensive approach, this study expands previously described correlations between genomic drivers and clinical features, enhancing our understanding of meningioma pathogenesis, and laying further groundwork for the use of targeted therapies. Importantly, the authors found that noninvasive patient variables exhibited a moderate predictive value of underlying genomic subgroup, which could improve with additional training data. With continued development, this framework may enable selection of appropriate precision medications without the need for invasive sampling procedures.

Tumor Vessel Normalization, Immunostimulatory Reprogramming, and Improved Survival in Glioblastoma with Combined Inhibition of PD-1, Angiopoietin-2, and VEGF

Glioblastoma (GBM) is a non-T-cell-inflamed cancer characterized by an immunosuppressive microenvironment that impedes dendritic cell maturation and T-cell cytotoxicity. Proangiogenic cytokines such as VEGF and angiopoietin-2 (Ang-2) have high expression in glioblastoma in a cell-specific manner and not only drive tumor angiogenesis and vascular permeability but also negatively regulate T-lymphocyte and innate immune cell responses. Consequently, the alleviation of immunosuppression might be a prerequisite for successful immune checkpoint therapy in GBM. We here combined antiangiogenic and immune checkpoint therapy and demonstrated improved therapeutic efficacy in syngeneic, orthotopic GBM models. We observed that blockade of VEGF, Ang-2, and programmed cell death protein-1 (PD-1) significantly extended survival compared with vascular targeting alone. In the GBM microenvironment, triple therapy increased the numbers of CTLs, which inversely correlated with myeloid-derived suppressor cells and regulatory T cells. Transcriptome analysis of GBM microvessels indicated a global vascular normalization that was highest after triple therapy. Our results propose a rationale to overcome tumor immunosuppression and the current limitations of VEGF monotherapy by integrating the synergistic effects of VEGF/Ang-2 and PD-1 blockade to reinforce antitumor immunity through a normalized vasculature.

Accuracy of Radiomics-Based Feature Analysis on Multiparametric Magnetic Resonance Images for Noninvasive Meningioma Grading

OBJECTIVE

Meningioma grading is relevant to therapy decisions in complete or partial resection, observation, and radiotherapy because higher grades are associated with tumor growth and recurrence. The differentiation of low and intermediate grades is particularly challenging. This study attempts to apply radiomics-based shape and texture analysis on routine multiparametric magnetic resonance imaging (MRI) from different scanners and institutions for grading.

METHODS

We used MRI data (T1-weighted/T2-weighted, T1-weighted-contrast-enhanced [T1CE], fluid-attenuated inversion recovery [FLAIR], diffusion-weighted imaging [DWI], apparent diffusion coefficient [ADC]) of grade I (n = 46) and grade II (n = 25) nontreated meningiomas with histologic workup. Two experienced radiologists performed manual tumor segmentations on FLAIR, T1CE, and ADC images in consensus. The MRI data were preprocessed through T1CE and T1-subtraction, coregistration, resampling, and normalization. A PyRadiomics package was used to generate 990 shape/texture features. Stepwise dimension reduction and robust radiomics feature selection were performed. Biopsy results were used as standard of reference.

RESULTS

Four statistically independent radiomics features were identified as showing the strongest predictive values for higher tumor grades: roundness-of-FLAIR-shape (area under curve [AUC], 0.80), cluster-shades-of-FLAIR/T1CE-gray-level (AUC, 0.80), DWI/ADC-gray-level-variability (AUC, 0.72), and FLAIR/T1CE-gray-level-energy (AUC, 0.76). In a multivariate logistic regression model, the combination of the features led to an AUC of 0.91 for the differentiation of grade I and grade II meningiomas.

CONCLUSIONS

Our results indicate that radiomics-based feature analysis applied on routine MRI is viable for meningioma grading, and a multivariate logistic regression model yielded strong classification performances. More advanced tumor stages are identifiable through certain shape parameters of the lesion, textural patterns in morphologic MRI sequences, and DWI/ADC variability.

Independent Risk Factors for Postoperative Seizures in Chronic Subdural Hematoma Identified by Multiple Logistic Regression Analysis

BACKGROUND

Postoperative seizures are potential complications of chronic subdural hematoma (cSDH). Knowledge of risk factors may help to identify patients that may benefit from antiepileptic prophylaxis.

METHODS

A total of 101 patients (mean age, 70.1 ± 32.1 years) with surgical evacuation of cSDH were enrolled. We retrospectively collected patient characteristics, hematoma specifics, and procedural aspects and evaluated their impact on postoperative seizures within a 14-day follow-up period by means of bivariate logistic regression analysis.

RESULTS

Postoperative seizures occurred in 14 patients (13.9%). At discharge, the mean Markwalder grading scale score was 1.1 ± 1.1 and 0.5 ± 0.8 in patients with and without seizures, respectively (P = 0.04). In the univariate analysis, preoperative midline shift (8.3 vs. 4.5 mm, P = 0.045), open craniotomy (85.7% vs. 55.2%, P = 0.031), and membranectomy (57.1% vs. 20.7%, P = 0.004) were significantly associated with postoperative seizures, respectively. In the multivariate analysis, preoperative midline shift (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.01-1.26; P = 0.029) and membranectomy (OR, 3.9; 95% CI, 1.0-15.0; P = 0.048) remained as independent risk factors for seizures.

CONCLUSIONS

Perioperative antiepileptic prophylaxis may be recommended in patients with preoperative midline shift. Membranectomy may not be routinely applied during surgery.

Death Receptor 6 (DR6) Is Overexpressed in Astrocytomas

BACKGROUND/AIM

Death receptor 6 (DR6) is a member of the tumor necrosis factor receptor superfamily. The expression of DR6 is elevated in different kinds of tumors including ovarian, breast cancer and adult sarcoma. In these tumors, the receptor may be handled as a new diagnostic and prognostic marker. Thus, we investigated the expression of DR6 in gliomas.

MATERIALS AND METHODS

Tumor and control tissues were extracted during neurosurgery and grouped according to the WHO classification. DR6 expression was investigated in low- and high-grade gliomas PCR (n=70), immunofluorescence staining (n=33) and western blot (n=58). Additional analysis of TCGA-data was performed to assess the general alteration of DR6 in cancer and influence of IDH-mutation on DR6 expression in gliomas.

RESULTS

The expression of DR6 was significantly enhanced in gliomas (p<0.05). It showed a trend towards rising expression with increasing malignancy of the tumor. Chemotherapy treatment could have an influence on DR6 expression.

CONCLUSION

In our investigation, DR6 acts as a potential suitable diagnostic marker for gliomas.

Expression of CD40 Correlates Negatively with Overall and Progression-Free Survival of Low- and High-Grade Gliomas

BACKGROUND

Low-grade gliomas (LGGs) are known to progress to glioblastoma (GBM), decreasing the chances of survival. The tumor necrosis factor receptor CD40 and its ligand CD40L have shown value as biomarkers for GBM. The present study evaluated the role of CD40/CD40L in LGG and GBM in differentiating isocitrate dehydrogenase (IDH) wild-type and IDH-mutant GBM.

METHODS

The present study was based on patient-derived samples (74 grade II gliomas, 36 grade III gliomas, and 40 cases of GBM) and expression analysis using real-time polymerase chain reaction. Open-access data from The Cancer Genome Atlas (TCGA) and the strong cohorts of TCGA data sets "brain lower grade glioma" and "glioblastoma" were used to run the analysis on mRNA expression as a validation data set.

RESULTS

We found that patients with LGG and CD40 overexpression experienced shorter progression-free survival (43 vs. 29 months; hazard ratio, 0.5715; P = 0.0262) and overall survival (116 vs. 54 months; hazard ratio, 0.3431; P < 0.0001). Consistently, relapsed grade II glioma showed greater CD40 expression compared with primary grade II glioma (P = 0.0028). Just as with LGG, CD40 was a negative marker for overall survival in GBM (12 vs. 10 months; hazard ratio, 0.5178; P = 0.0491). In this context, we found greater CD40 expression in IDH wild-type GBM than in IDH-mutant GBM. The data obtained from TCGA supported our findings, with similar results for PFS and OS in LGG and GBM. CD40L expression showed no correlation with the survival data.

CONCLUSION

High CD40 expression showed a significant correlation with poor outcomes for both LGG and GBM and was overexpressed in IDH wild-type GBM.

Qualitative and Quantitative Analysis of IDH1 Mutation in Progressive Gliomas by Allele-Specific qPCR and Western Blot Analysis

To date, diagnosis of IDH1 mutation is based on DNA sequencing and immunohistochemistry, methods limited in terms of sensitivity and ease of use. Recently, the diagnosis of IDH1 mutation by real-time polymerase chain reaction was introduced as an alternative method. In this study, real-time polymerase chain reaction was validated as a tool for detection of IDH1 mutation, and expression levels were analyzed for correlation with course of the disease. A total of 113 tumor samples were obtained intraoperatively from 84 patients with glioma having a diagnosis of diffuse glioma (World Health Organization II), anaplastic glioma (World Health Organization III), secondary glioblastoma ± chemotherapy, primary glioblastoma ± chemotherapy (World Health Organization IV). Tumor samples were snap frozen and processed for sectioning and RNA and protein isolation. Presence of IDH1 mutation was determined by DNA sequencing. Hereafter, quantitative expression of IDH1 messenger RNA was assessed using real-time polymerase chain reaction with specific primers for IDH1 mutation and -wt; protein expression was verified by Western Blot analysis and immunohistochemistry. Additionally, 19 samples of low-grade glioma and their consecutive high-grade glioma were analyzed at different time points of the disease. IDH1 mutation was identified in 63% of samples by DNA sequencing. In correlation with the real-time polymerase chain reaction results, a cutoff value was determined. Above this threshold, sensitivity and specificity of real-time polymerase chain reaction in detecting IDH1 mutation were 98% and 94%, respectively. Quantitative analysis revealed that IDH1 mutation expression is upregulated in secondary glioblastoma (mean ± standard error of mean: 3.52 ± 0.55) compared to lower grade glioma (II = 1.54 ± 0.22; III = 1.67 ± 0.23). In contrast, IDH1 wt expression is upregulated in all glioma grades (concentration >0.1) compared to control brain tissue (0.007 ± 0.0016). Western Blot analysis showed a high concordance to both sequencing and real-time polymerase chain reaction results in qualitative analysis of IDH1 mutation status (specificity 100% and sensitivity 100%). Moreover, semiquantitative protein expression analysis also showed higher expression levels of mutated IDH1 in secondary glioblastoma. In our study, real-time polymerase chain reaction and Western Blot analysis were found to be highly efficient methods in detecting IDH1 mutation in glioma samples. As cost-effective and time-saving methods, real-time polymerase chain reaction and Western Blot analysis may therefore play an important role in IDH1 mutation analysis in the future. IDH1 mutation expression level was found to correlate with the course of disease to a certain extent. Yet, clinical factors as recurrent disease or prior radiochemotherapy did not alter IDH1 mutation expression level.

Impact of time to initiation of radiotherapy on survival after resection of newly diagnosed glioblastoma

Background and purpose

To evaluate the effect of timing of radiotherapy (RT) on survival in patients with newly diagnosed primary glioblastoma (GBM) treated with the same therapeutical protocol.

Materials and methods

Patients with newly diagnosed primary GBM treated with the same therapeutical scheme between 2010 and 2015 in our institution were retrospectively reviewed. The population was trichotomized based on the time interval from surgery till initiation of RT (< 28 days, 28–33 days, > 33 days). Kaplan-Meier and Cox regression analyses were used to compare progression free survival (PFS) and overall survival (OS) between the groups. The influence of various extensively studied prognostic factors on survival was assessed by multivariate analysis.

Results

One-hundred-fifty-one patients met the inclusion criteria. Between the three groups no significant difference in PFS (p = 0.516) or OS (p = 0.902) could be demonstrated. Residual tumor volume (RTV) and midline structures involvement were identified as independent prognostic factors of PFS while age, O-6-Methylguanine Methyltransferase (MGMT) status, Ki67 index, RTV and midline structures involvement represented independent predictors of OS. Patients starting RT after a prolonged delay (> 48 days) exhibited a significantly shorter OS (p = 0.034).

Conclusion

Initiation of RT within a timeframe of 48 days is not associated with worsened survival. A prolonged delay (> 48 days) may be associated with worse OS. RT should neither be delayed, nor forced, but should rather start timely, as soon as the patient has recovered from surgery.

A DNA Repair and Cell-Cycle Gene Expression Signature in Primary and Recurrent Glioblastoma: Prognostic Value and Clinical Implications

Inevitable tumor recurrence and a poor median survival are frustrating reminders of the inefficacy of our current standard of care for patients with newly diagnosed glioblastoma (GBM), which includes surgery followed by radiotherapy and chemotherapy with the DNA alkylating agent temozolomide. Because resistance to genotoxic damage is achieved mainly through execution of the DNA damage response (DDR) and DNA repair pathways, knowledge of the changes in DNA repair and cell-cycle gene expression that occur during tumor development might help identify new targets and improve treatment. Here, we performed a gene expression analysis targeting components of the DNA repair and cell-cycle machineries in cohorts of paired tumor samples (i.e., biopsies from the same patient obtained at the time of primary tumor operation and at recurrence) from patients treated with radiotherapy or radiotherapy plus temozolomide. We identified and validated a 27-gene signature that resulted in the classification of GBM specimens into three groups, two of which displayed inverse expression profiles. Each group contained primary and recurrent samples, and the tumor at relapse frequently displayed a gene expression profile different from that of the matched primary biopsy. Within the groups that exhibited opposing gene expression profiles, the expression pattern of the gene signature at relapse was linked to progression-free survival. We provide experimental evidence that our signature exposes group-specific vulnerabilities against genotoxicants and inhibitors of the cell cycle and DDR, with the prospect of personalized therapeutic strategies.Significance: These findings suggest that classification of GBM tumors based on a DNA repair and cell-cycle gene expression signature exposes vulnerabilities to standard-of-care therapies and offers the potential for personalized therapeutic strategies.

ACTB and SDHA Are Suitable Endogenous Reference Genes for Gene Expression Studies in Human Astrocytomas Using Quantitative RT-PCR

Background:

Quantitative real-time reverse-transcription polymerase chain reaction is frequently used as research tool in experimental oncology. There are some studies of valid endogenous control genes in the field of human glioma research, which, however, only focus on the comparison between normal brain with tumor tissue and malignant transformation toward secondary glioblastomas. Aim of this study was to validate a more general reference gene also suitable for pre- and posttreatment analysis and other evaluations (eg, primary vs secondary glioblastoma).

Methods:

This quantitative polymerase chain reaction analysis was performed to test a panel of the 6 most suitable reference genes from other studies representing different physiological pathways (ACTB, GAPDH, POLR2A, RPL13A, SDHA, and TBP) in all common glioma groups, namely: diffuse astrocytoma World Health Organization II, anaplastic astrocytoma World Health Organization III, secondary glioblastoma World Health Organization IV with and without chemotherapy, primary glioblastoma, recurrent glioblastoma, and gliomas before and after radiation. Expression stability was tested during the longitudinal course of the disease in 8 single patients.

Results:

Evaluation of the expression levels of the 6 target genes showed that ACTB, GAPDH, and RPL13A show higher expression compared to SDHA, POLR2A, and TBP. ACTB, GAPDH, and RPL13A showed different expression levels between astrozytoma grade II and primary glioblastoma. Except for this difference, the candidate genes were not differentially expressed between primary and secondary glioblastomas and between the World Health Organization tumor grades. Furthermore, they remained stable before and after radiotherapy and/or chemotherapy. Therefore, they are adequate references for glioblastoma gene expression studies. The comparison of all tested genes resulted in SDHA and ACTB as most stable reference genes determined by the NormFinder software. Our data revealed lowest intragroup variation in the SDHA, highest in the RPL13A gene.

Conclusions:

All tested genes may be recommended as universal reference genes for data normalization in gene expression studies under different treatment regimens both in primary glioblastomas and astrocytomas of different grades (World Health Organization grades II-IV), respectively. In summary, ACTB and SDHA exhibited the best stability values and showed the lowest intergroup expression variability.

Survival effects of a strategy favoring second-line multimodal treatment compared to supportive care in glioblastoma patients at first progression

OBJECTIVE

Data on the survival effects of supportive care compared to second-line multimodal treatment for glioblastoma progression are scarce. Thus, the authors assessed survival in two population-based, similar cohorts from two European university hospitals with different treatment strategies at first progression.

METHODS

The authors retrospectively identified patients with newly diagnosed glioblastoma treated at two neurooncological centers. After diagnosis, patients from both centers received identical treatments, but at tumor progression each center used a different approach. In the majority of cases, at center A (Greece), supportive care or a single therapeutic modality was offered at progression, whereas center B (Germany) provided multimodal second-line therapy. The main outcome measure was survival after progression (SaP). The influence of the treatment strategy on SaP was assessed by multivariate analysis.

RESULTS

One hundred three patients from center A and 156 from center B were included. Tumor progression was observed in 86 patients (center A) and 136 patients (center B). At center A, 53 patients (72.6%) received supportive care alone, while at center B, 91 patients (80.5%) received second-line treatment. Progression-free survival at both centers was similar (9.4 months [center A] vs 9.0 months [center B]; p = 0.97), but SaP was significantly improved in the patients treated with multimodal second-line therapy at center B (7 months, 95% CI 5.3-8.7 months) compared to those treated with supportive care or a single therapeutic modality at center A (4.5 months, 95% CI 3.5-5.5 months; p = 0.003). In the multivariate analysis, the treatment center was an independent prognostic factor for overall survival (HR 1.59, 95% CI 0.17-2.15; p = 0.002).

CONCLUSIONS

Treatment strategy favoring multimodal second-line treatment over minimal treatment or supportive care at glioblastoma progression is associated with significantly better overall survival.