TMET-09. LOSS OF MAT2A COMPROMISES METHIONINE METABOLISM AND REPRESENTS A VULNERABILITY IN H3K27M MUTANT GLIOMAS

H3K27-mutant diffuse midline gliomas (DMGs) are defined as grade IV tumors by the World Health Organization. DMGs are inoperable and resistant to chemo/radio therapies. Median survival ranges from 8-11 months, with 2% of patients surviving beyond 5 years. H3K27M mutations lead to global epigenetic and transcriptional reprogramming driven by global loss of negative transcriptional regulator H3K27 trimethylation (H3K27me3). Loss of H3K27me3 is an initiating event in gliomagenesis. This disease lacks appropriate models to predict disease biology and response to treatment. Therefore, we developed a novel syngeneic H3K27M mouse model. An unbiased integrated systems biology approach identified that H3K27M but not isogenic controls relied on the amino acid methionine and the enzyme Methionine Adenosyltransferase 2A (MAT2A). MAT2A is a central regulator of one-carbon metabolism by converting methionine to S-adenosylmethionine (SAM), the universal methyl-donor for protein and nucleotide methylation reactions. In complementary genetic approaches, we applied these findings to patient-derived cell lines with the H3K27M mutation. We hypothesize that MAT2A abrogation, genetic/pharmacological, would alter DMG viability by disrupting the methylome. The current MAT2A sensitivity paradigm is based on Methylthioadenosine Phosphorylase (MTAP) deletion through a synthetic lethal mechanism. We provide a novel mechanism whereby H3K27M cells are sensitive to MAT2A loss, independent of MTAP and through Adenosylmethionine Decarboxylase 1 (AMD1) overexpression disrupting MAT2A regulation. This results in H3K27M cells having lower MAT2A protein levels, conferring a sensitivity by inhibiting residual MAT2A. Genetic/pharmacological aberrations to MAT2A resulted in reduced proliferation. Parallel H3K36me3 ChIP and RNA-sequencing identified loss of oncogenic and developmental transcriptional programs associated with MAT2A loss. In vivo syngeneic and patient-derived xenograft models with both inducible MAT2A knockdown or methionine restricted diets showed extended survival. These results suggest novel interactions between methionine metabolism and the epigenome of H3K27M gliomas and provide evidence that MAT2A, presents exploitable therapeutic vulnerabilities in histone mutant gliomas.

Predictors of first pass effect and effect on outcomes in mechanical thrombectomy for basilar artery occlusion

INTRODUCTION

For patients undergoing endovascular thrombectomy (EVT), those who are recanalized with a successful single pass (first pass effect, FPE) have better functional outcomes than those who do not. There is a scarcity of data regarding predictors of FPE in basilar artery occlusion (BAO). We aim to determine what characteristics may predict FPE for posterior circulation thrombectomies in a cohort of patients undergoing EVT for BAO.

METHODS

We reviewed prospectively-collected data for patients presenting to a comprehensive stroke center with BAO between December 2015 and April 2019. Patients were included in this study if they underwent manual aspiration thrombectomy for BAO. Patients were excluded if they had occlusions of the posterior cerebral or vertebral arteries or if they had tandem lesions. Patients were stratified by whether FPE or modified FPE (mFPE) was achieved, and multivariate logistic regression analyses were performed to identify predictors of FPE and the effect of FPE on clinical outcome.

RESULTS

100 patients with BAO underwent thrombectomy. Mean age was 64.7 ± 16.7, 42% were female, and median NIHSS was 20 (IQR 11-27). 33% met criteria for FPE and 60% for mFPE. Univariate analysis identified female gender, lack of IV-tPA use, pcASPECTS, atrial fibrillation, and hyperlipidemia as possible predictors of FPE. On multivariate analysis, age, pcASPECTs, atrial fibrillation, hyperlipidemia and IV-tPA use were not independent predictors of FPE or mFPE. Female gender was an independent predictor of mFPE (p = 0.02), but not FPE (p = 0.18). FPE was a predictor of mRS 0-2 at 90 days (p = 0.04). Predictors of mortality were age (p < 0.01), baseline NIHSS (p < 0.01) and mFPE (p = 0.01).

CONCLUSION

In this cohort analysis of 100 patients with basilar artery occlusion undergoing manual aspiration thrombectomy, female gender was associated with mFPE but not FPE. Previously-reported anterior circulation FPE predictors including age, ASPECTS and atrial fibrillation were not predictors of FPE in this cohort of patients with BAO.

Outcome Prediction in Patients with Severe Traumatic Brain Injury Using Deep Learning from Head CT Scans

Background After severe traumatic brain injury (sTBI), physicians use long-term prognostication to guide acute clinical care yet struggle to predict outcomes in comatose patients. Purpose To develop and evaluate a prognostic model combining deep learning of head CT scans and clinical information to predict long-term outcomes after sTBI. Materials and Methods This was a retrospective analysis of two prospectively collected databases. The model-building set included 537 patients (mean age, 40 years ± 17 [SD]; 422 men) from one institution from November 2002 to December 2018. Transfer learning and curriculum learning were applied to a convolutional neural network using admission head CT to predict mortality and unfavorable outcomes (Glasgow Outcomes Scale scores 1-3) at 6 months. This was combined with clinical input for a holistic fusion model. The models were evaluated using an independent internal test set and an external cohort of 220 patients with sTBI (mean age, 39 years ± 17; 166 men) from 18 institutions in the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study from February 2014 to April 2018. The models were compared with the International Mission on Prognosis and Analysis of Clinical Trials in TBI (IMPACT) model and the predictions of three neurosurgeons. Area under the receiver operating characteristic curve (AUC) was used as the main model performance metric. Results The fusion model had higher AUCs than did the IMPACT model in the prediction of mortality (AUC, 0.92 [95% CI: 0.86, 0.97] vs 0.80 [95% CI: 0.71, 0.88]; P < .001) and unfavorable outcomes (AUC, 0.88 [95% CI: 0.82, 0.94] vs 0.82 [95% CI: 0.75, 0.90]; P = .04) on the internal data set. For external TRACK-TBI testing, there was no evidence of a significant difference in the performance of any models compared with the IMPACT model (AUC, 0.83; 95% CI: 0.77, 0.90) in the prediction of mortality. The Imaging model (AUC, 0.73; 95% CI: 0.66-0.81; P = .02) and the fusion model (AUC, 0.68; 95% CI: 0.60, 0.76; P = .02) underperformed as compared with the IMPACT model (AUC, 0.83; 95% CI: 0.77, 0.89) in the prediction of unfavorable outcomes. The fusion model outperformed the predictions of the neurosurgeons. Conclusion A deep learning model of head CT and clinical information can be used to predict 6-month outcomes after severe traumatic brain injury. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Haller in this issue.

Successful reperfusion, rather than number of passes, predicts clinical outcome after mechanical thrombectomy

Introduction

For patients undergoing mechanical thrombectomy, numerous (>3) thrombectomy passes may be harmful. However, non-recanalization leads to poor outcomes. For patients requiring multiple thrombectomy passes to achieve reperfusion, it remains unclear if the risk/benefit ratio favors recanalization.

Objective

To test the hypothesis that the benefits afforded by successful reperfusion outweigh the risk conveyed by the numerous passes required.

Methods

We retrospectively reviewed prospectively collected data for patients presenting to a comprehensive stroke center with anterior circulation large vessel occlusion (ACLVO) and undergoing thrombectomy requiring more than one pass over 24 months. We stratified patients into three groups: group 1 (successful reperfusion in 2–3 passes), group 2 (successful reperfusion in ≥4 passes), and group 3 (unsuccessful reperfusion).

Results

250 patients with ACLVO constituted the study cohort. Despite similar demographics, group 2 patients had better clinical outcomes than those in group 3 at 24 hours (National Institutes of Health Stroke Scale (NIHSS) score 13.5 vs 19.1, p<0.001) and at 90 days (modified Rankin Scale score 0–2 rates of 31.1% vs 0.0%, p=0.006) On multivariate logistic regression analysis, age (p=0.034), Alberta Stroke Program Early CT Score (p<0.01), NIHSS score (p=0.02), and parenchymal hematoma type 2 (p=0.015) were significant predictors of functional independence among those who achieved successful reperfusion, but the number of passes required did not predict outcome for these patients (p=0.74).

Conclusion

Patients who achieve successful reperfusion after many passes have better clinical outcomes than those who do not, despite the number of passes and procedural time required. The number of passes required to achieve successful reperfusion beyond the first pass is not a predictor of functional independence.

Stentriever salvage after failed manual aspiration thrombectomy

Introduction

Manual aspiration thrombectomy (MAT) and stent retriever mediated aspiration thrombectomy (SMAT) are well described reperfusion strategies for large vessel occlusions. This study aims to identify predictors of successful crossover to SMAT after failed first pass MAT.

Methods

Prospectively collected data for patients with acute large vessel occlusions undergoing thrombectomy over a 23 month period at a comprehensive stroke center were reviewed. The primary outcome was successful removal of the index clot with resultant Thrombolysis in Cerebral Infarction 2b or greater reperfusion at any point after a failed initial MAT attempt, and multivariate logistic regression analyses were performed to determine predictors of successful crossover to SMAT.

Results

Of 433 large vessel thrombectomies, 319 underwent first pass MAT, and 113 patients required a repeated pass for the index thrombus. Second pass MAT was performed in 77% of cases and was successful in 54%; second pass SMAT was performed in 23% of cases and was successful in 73% (P=0.11). Third pass MAT was employed in 45% of cases and was successful in 43% while SMAT was performed in 55% of cases and was successful in 77% (P=0.03). Overall, 12% of patients undergoing MAT on the first pass crossed over to successful SMAT. Predictors of successful crossover were internal carotid artery (ICA) location and higher presenting National Institutes of Health Stroke Scale (NIHSS) score.

Conclusion

After failed first pass MAT, subsequent passes with SMAT had higher rates of successful index clot removal; patients with a higher initial NIHSS score and ICA clot location should be considered for early crossover or even initial SMAT for their clots.

Large-bore aspiration catheter selection does not influence reperfusion or outcome after manual aspiration thrombectomy

INTRODUCTION

Various large-bore catheters can be employed for manual aspiration thrombectomy (MAT); clinical differences are rarely explored.

METHODS

Prospectively collected demographic, angiographic, and clinical data for patients with acute internal carotid artery, middle cerebral artery M1, or basilar occlusions undergoing MAT over 23 months at a comprehensive stroke center were reviewed. We excluded patients in stentriever-based randomized trials/registries. The four most commonly utilized aspiration catheters were analyzed, and multivariate logistic regression analyses were performed to determine the effect of primary aspiration catheter choice on first-pass success, final reperfusion, and modified Rankin Scale (mRS) score at 90 days.

RESULTS

Of 464 large vessel thrombectomies, 180 were performed via MAT on the first pass with one of four catheters. First-pass success was achieved in 42% of cases overall; this rate did not differ significantly between catheters: 50% for Sofia, 45% for CAT6, 40% for 0.072 inch Navien, and 36% for ACE68, p=0.67. Final Thrombolysis in Cerebral Infarction 2b or 3 reperfusion was achieved in 94% of cases overall: 97% of cases with CAT6, 95% with Sofia, 92% with Navien, and 92% with ACE68, p=0.70. Mean number of passes for index thrombus (2.0 overall), median procedure time (32 min overall), 90-day good outcome (mRS 0-2, mean 36%), and 90-day mortality (mean 27%) did not differ significantly between patients treated with different initial catheters.

CONCLUSION

Among large-bore aspiration catheters, catheter selection is not an independent predictor of first-pass success, final reperfusion, or clinical outcome.

A preliminary survey of the nematode parasites of some imported Old-World monkeys

Faecal samples and blood films from 3 species of Old-World monkeys, Macaca mulatta, Macaca irus and Papio dogeura, were examined for the presence of nematode parasites. 8 separate groups, a total of 200 animals, were examined within 24 hours of their arrival at the premises of a primate importer. 8 species of nematode were found to be common inhabitants of the alimentary tract, and small numbers of microfilaria were detected in all groups.