Neth, Bryan J.

Abstract Extracellular vesicles have emerged as a less-invasive nano-tool for discovering biomarkers of Alzheimer’s disease and related dementia. Here, we analysed different neuron-enriched extracellular vesicles from plasma to predict response and molecular mechanisms of ketogenic diet’s efficacy in mild cognitive impairment participants. The study was a randomized crossover design in which cognitively normal and mild cognitive impairment participants consumed a modified Mediterranean-ketogenic diet or American Heart Association diet for 6 weeks, followed by other diet after washout. L1 cell adhesion molecule, synaptophysin and neural cell adhesion molecule surface markers were used to enrich for neuron-secreted small extracellular vesicles (sEVL1CAM, sEVSYP and sEVNCAM). For the first time, we have presented multiple evidences, including immunogold labelling/transmission electron microscopy, clusters of differentiation 63-ELISA-based assay, confocal microscopy fluorescent images and flow cytometry data confirming the presence of L1 cell adhesion molecule on the surface of sEVL1CAM, validating purity and relative abundance of sEVL1CAM in the plasma. Cargo analysis of sEVL1CAM showed that modified Mediterranean-ketogenic diet intervention reduces amyloid beta 1–42 (50.3%, P = 0.011), p181-tau (34.9%, P = 0.033) and neurofilament light (54.2%, P = 0.020) in mild cognitive impairment participants. Moreover, sEVL1CAMshowed better sensitivity compared with CSF in analysing increased glutamate (6-folds, P < 0.0001) from mild cognitive impairment participants following modified Mediterranean-ketogenic diet intervention. sEVL1CAM characterization also suggested that modified Mediterranean-ketogenic diet differentially targets the expression of various glutamate receptors—glutamate receptor ionotropic NMDA1, glutamate receptor ionotropic NMDA2A, glutamate receptor ionotropic NMDA2B and glutamate receptor ionotropic AMPA type subunit 1. Importantly, these sEVL1CAM measures strongly correlated with corresponding clinical CSF biomarkers (neurogranin, amyloid beta 1–42, neurofilament light and tau). Furthermore, sEVL1CAM were loaded with less advanced glycation endproducts and exhibited anti-inflammatory activity following modified Mediterranean-ketogenic diet intervention. Most importantly, the expression of monocarboxylate transporter 2 on the surface of sEVL1CAM predicted the amyloid beta 1–42 response to modified Mediterranean-ketogenic diet intervention (area under the curve = 0.87, P = 0.0044) and offered a novel screening tool to identify participants responsive to this dietary intervention. Finally, sEVL1CAM, sEVSYP and sEVNCAM showed significantly high concordance in analysing amyloid beta 1–42 (Pearson correlation coefficient ≥ 0.63, P < 0.01) and neurofilament light (Pearson correlation coefficient ≥ 0.49, P < 0.05). Together, small extracellular vesicles in plasma offers promise in assessing the efficacy of dietary/therapeutic intervention against mild cognitive impairment/Alzheimer’s disease.

Abstract Gliomas may leverage alternate metabolic pathways in response to metabolism-targeted therapeutic intervention, all of which remain unexplored in the live human glioma, in situ. Defining emergent mechanisms of metabolic resistance in response to therapeutic challenge can help guide rational combinatorial therapies. To date, the metabolic response of gliomas in response to therapeutic intervention has remained poorly understood due to the relative inaccessibility of the live human tumor, in situ. Microdialysis is an underutilized tool that could be leveraged to overcome this longstanding challenge. Data from our ongoing intraoperative microdialysis trial have revealed an upregulation of polyamine metabolism and a novel glioma-associated metabolite, guanidinoacetate (GAA) -- a metabolite co-produced with ornithine, which is required for polyamine synthesis. In a Phase 0 trial, we will evaluate in situ glioma responses to polyamine depletion (difluoromethylornithine, DFMO) with or without blockade of polyamine uptake (AMXT 1501) to identify candidate extracellular biomarkers of target engagement and cytotoxicity in fifteen post-operative patients who have undergone a standard-of-care planned subtotal resection for high-grade glioma. Intraoperatively, high-molecular-weight catheters will be implanted into the residual tumor and brain adjacent to the resection cavity for post-operative longitudinal monitoring of extracellular metabolites via microdialysis. Polyamines and guanidinoacetate, a candidate biomarker of glioma-upregulated polyamine synthesis, will be monitored throughout therapeutic intervention from post-operative day (POD) 1 to POD5 via longitudinal microdialysis to determine live in situ glioma pharmacodynamic responses to polyamine depletion. Catheters will be removed on post-operative day five prior to discharge. We hypothesize that GAA will reflect local tumor production of polyamine metabolism. Additionally, in situ microdialysis in Phase 0 trials will allow for pharmacodynamic and pharmacokinetic, in addition to metabolic, monitoring, an opportunity which is rarely afforded in most clinical trials due to lack of access to the CNS.

Angioinvasive fungal infections of the cerebral vasculature often lead to significant morbidity and mortality. High clinical suspicion and early antifungal therapy could improve outcomes. We describe the fatal case of a patient with a rapidly enlarging cavernous carotid aneurysm due to angioinvasive fungus. This case highlights the challenges in diagnosis and management of this condition.

Introduction: A common risk factor of chronic, nontraumatic subdural hematoma (SDH) is anticoagulation therapy. Anticoagulation is generally held in patients who develop SDH, but this can lead to thromboembolic events. While prior studies have reported the clinical outcomes of patients with anticoagulation-related SDH, there remains little evidence regarding ongoing anticoagulation treatment. Case Report: We report the management of 2 patients who developed anticoagulation-related SDH and underwent middle meningeal artery (MMA) embolization and successful reinitiation of anticoagulation therapy. In both patients, we conservatively managed anticoagulation with heparin and/or enoxaparin as a bridge to warfarin after MMA embolization. Follow-up computed tomography head revealed interval decrease of SDH and stable neurological status. Conclusions: These cases provide anecdotal evidence of a challenging clinical scenario where there is a necessary indication for therapeutic anticoagulation (ie, venous sinus thrombosis or atrial appendage thrombus) and comorbid SDH. Endovascular MMA embolization may be an effective adjunct therapy for clinical scenarios in patients with SDH and an urgent indication for anticoagulation. Longer follow-up, prospective series, and future randomized clinical trials are needed to objectively assess outcomes in this clinically challenging patient population.

Background: Survival of patients with glioblastoma (GBM) increased in the 2000s, most prominently after the addition of temozolomide to the standard-of-care treatment protocol. The reason for subsequent improvements in survival in the late 2000s and early 2010s was less clear, with explanations including the introduction of bevacizumab, better surgical methods, and advances in supportive care. It is uncertain whether the trend of improving population-level survival has continued. Materials and Methods: Data from the Surveillance, Epidemiology, and End Results (SEER) Program was analyzed comparing survival of adult GBM patients diagnosed in consecutive 3-year periods from 2000 to 2017. Kaplan-Meier survival analysis and Cox proportional hazards models were used. Results: A total of 38,352 patients diagnosed with GBM between 2000 and 2017 met inclusion criteria. Median survival and percent survival to 12 and 24 months all progressively increased between 2000 and 2011. There were no significant differences in survival comparing 2009-2011 with 2012-2014 or 2015-2017. During the 2015-2017 period, median survival was 11 months, with 12 and 24-month survival proportions of 45.7% (95% confidence interval, 44.5-47.0) and 19.0% (95% confidence interval, 18.6-21.2), respectively. Conclusions: After a period of progressive improvement in GBM survival between 2000 and 2011, survival plateaued. Subsequent advances since 2011 have not yet been translated to improved survival on the population-level as of 2017.

Abstract Stroke-Like Migraine Attacks after Radiation Therapy (SMART) is a descriptive clinical entity consisting of transient hemispheric dysfunction. We were interested in pragmatic management patterns for patients with Recurrent Stroke-Like Episodes (R-SLE) of transient negative neurologic symptoms after cranial radiotherapy (RT) to define optimal management strategy and assess long-term outcomes. We conducted a retrospective review of all patients with recurrent negative neurologic symptoms after cranial RT who were treated at Mayo Clinic (Rochester), with follow-up extending until February 2021. Descriptive statistics and Chi-Square analysis was performed to assess for differences between patients with clinical cessation of symptoms, death, progressive encephalopathy and therapeutic class, patient and primary treatment characteristics (i.e. whole brain RT). We identified 27 patients with R-SLE after RT. 25 patients were included in analyses. Median age at diagnosis was 28.7 years (3.0-65.8 years, SD: 15.0 years). Median time from RT to symptom onset was 14.6 years (3.3-30.5 years, SD: 8.9 years). The most common presentations included hemiparesis (55.6%), hemisensory loss (22.2%), transient visual field loss (33.3%), encephalopathy (18.5%), and aphasia (22.2%). Antiseizure medications were most used for management of R-SLE (92%) followed by anti-platelets (68%), verapamil (52%), statins (48%), glucocorticoids (24%), antivirals (20%), and ACE inhibitors/angiotensin receptor blockers (16%). Beta blockers were not used. Verapamil use was frequently associated with clinical cessation of recurrent events with cessation being achieved in 64.7% of patients on verapamil versus 35.3% not on verapamil (p=0.0638). Other medical interventions did not approach clinical or statistical significance. Progressive encephalopathy was more common in patients without clinical cessation (87.5% vs. 23.5%, p=0.0026). All patients who died at last follow-up had progressive encephalopathy. We found cessation of recurrent negative neurologic symptoms after cranial RT in most patients. Verapamil use was associated with clinical cessation. Progressive encephalopathy was more common in patients without clinical cessation of recurrent events.

Abstract Medulloblastoma is a posterior fossa tumor rarely diagnosed in adults. Treatment includes craniospinal irradiation (CSI). Proton CSI is increasingly utilized to decrease radiation dose to normal tissues, despite the lack of randomized data demonstrating decreased toxicity compared to photon CSI. This single institution retrospective study of 39 adult medulloblastoma patients includes nineteen patients treated with photon CSI prior to 2015, and twenty treated with proton CSI thereafter. Median age was 28 years (range 18-66). Molecular subtype was most commonly sonic hedgehog (68%). The most common fractionation schedule was 36 Gy CSI in 20 fractions (85% of photon and 58% of proton patients) with a boost to 54-55.8 Gy (92%). Proton CSI delivered significantly lower mean doses to the cochleae (median 32 Gy vs. 44 Gy), lacrimal glands (8 vs. 36 Gy), lens (2 vs. 28 Gy), parotid glands (3 vs. 26 Gy), pharyngeal constrictors (6 vs. 15 Gy), esophagus (2 vs. 29 Gy), heart (0 vs. 14 Gy), lungs (1 vs. 7 Gy), liver (0.1 vs. 7 Gy), and skin (38 vs. 51 Gy) (all p< 0.001). Patients receiving proton CSI had significantly lower rates of acute dysphagia of any grade (5% vs. 35%, p= 0.044) and decreased median weight loss during radiation (+1.0 vs. -2.8 kg, p= 0.011). Acute hospitalization was associated with increased weight loss (p= 0.009). Median follow-up was 2.9 and 12.9 years for proton and photon patients, respectively, limiting late toxicity and outcome comparisons. At last follow-up five photon patients had died (two of progressive disease, three without recurrence ages 41-63) and 21% had experienced major cardiovascular events. At 10 years, 89% were alive and 82% were recurrence free. In conclusion, this study demonstrates dosimetric improvements with proton CSI, potentially leading to decreased acute toxicity including dysphagia and weight loss during treatment.

Posterior fossa (PF) diffuse gliomas in pediatric patients frequently harbor the H3 K27M mutation. Among adults, PF diffuse gliomas are rare, with limited data regarding molecular features and clinical outcomes. We identified 28 adult PF diffuse glioma patients (17 males; median: 50 y, range: 19 to 78 y), with surgery performed at our institution (13 brainstem; 15 cerebellum). Histologic subtypes included anaplastic astrocytoma (n=21), glioblastoma (n=6), and diffuse astrocytoma (n=1). Immunohistochemistry was performed for H3 K27M (n=26), IDH1-R132H (n=28), and ATRX (n=28). A 150-gene neuro-oncology-targeted next-generation sequencing panel was attempted in 24/28, with sufficient informative material in 15 (51.7%). Tumors comprised 4 distinct groups: driver mutations in H3F3A (brainstem=4; cerebellum=2), IDH1 (brainstem=4; cerebellum=4), TERT promotor mutation (brainstem=0; cerebellum=3), and none of these (n=5), with the latter harboring mutations of TP53 , PDGFRA , ATRX , NF1 , and RB1 . All TERT promoter–mutant cases were IDH-wild-type and arose within the cerebellum. To date, 20 patients have died of disease, with a median survival of 16.3 months, 1-year survival of 67.5%. Median survival within the subgroups included: H3F3A =16.4 months, IDH mutant=113.4 months, and TERT promoter mutant=12.9 months. These findings suggest that PF diffuse gliomas affecting adults show molecular heterogeneity, which may be associated with patient outcomes and possible response to therapy, and supports the utility of molecular testing in these tumors.