MBRS-54. POOR SURVIVAL IN REPLICATION REPAIR DEFICIENT HYPERMUTANT MEDULLOBLASTOMA AND CNS EMBRYONAL TUMORS: A REPORT FROM THE INTERNATIONAL RRD CONSORTIUM

BACKGROUND

Mutations in mismatch repair (MMR) and DNA-polymerase (POL) genes lead to DNA replication repair deficiency (RRD), resulting in a growing group of previously under-recognized childhood brain tumors. Medulloblastoma and embryonal tumors are rarely reported in RRD. Their biological and clinical significance is unknown.

METHODS

We analyzed the clinical and genomic data of embryonal tumors registered in the International RRD Consortium.

RESULTS

Twenty-six tumors were centrally reviewed to confirm medulloblastoma (n=18), embryonal-tumor, NOS (n=5), and three glioblastoma (excluded). Embryonal tumors were observed at a young age (median: 7-years, IQR: 5;11), and all but one exhibited clinical cues (café-au-lait macules/ family history) of germline RRD. Medulloblastomas with RRD exhibited high-risk features, including anaplastic histology (50%), and SHH-subgroup with TP53-mutation (50%). Importantly, 68% harbored POLE/POLD1 mutations, resulting in median tumor mutation burden of 164 mut/mb. POL-mutated tumors were significantly ultra-hypermutated (>100 mut/mb) than tumors with MMR-deficiency alone (p=0.015). Synchronous and metachronous tumors were observed in 40%. However 90% of the deaths were related to the diagnosis of embryonal CNS tumor. Median survival for the entire cohort was 17-months (95% CI: 10 to 23). Predicted 3-year survival was 37% for medulloblastoma, with no survivors among other embryonal tumors.

CONCLUSIONS

This is the largest cohort of replication repair deficient medulloblastoma reported till date. The tumors are hypermutated, harbor somatic mutations in TP53 and/or POLE/POLD1, and have very poor survival with current chemo-irradiation based approaches. These biologically unique tumors expand the spectrum of high-risk TP53-mutant SHH-medulloblastoma, and need novel strategies for treatment.

PATH-22. COMPREHENSIVE ANALYSIS OF DIVERSE LOW-GRADE NEUROEPITHELIAL TUMORS WITH FGFR1 ALTERATIONS REVEALS A DISTINCT MOLECULAR SIGNATURE OF ROSETTE-FORMING GLIONEURONAL TUMOR

The FGFR1 gene encoding fibroblast growth factor receptor 1 has emerged as a frequently altered oncogene in the pathogenesis of multiple low-grade neuroepithelial tumor (LGNET) subtypes including pilocytic astrocytoma (PA), dysembryoplastic neuroepithelial tumor (DNT), rosette-forming glioneuronal tumor (RGNT), and extraventricular neurocytoma (EVN). These activating FGFR1 alterations in LGNET can include tandem duplication of the exons encoding the intracellular tyrosine kinase domain, in-frame gene fusions most often with TACC1 as the partner, or hotspot missense mutations within the tyrosine kinase domain (either p.N546 or p.K656). However, the specificity of these different FGFR1 events for the various LGNET subtypes and accompanying genetic alterations are not well defined, nor are the histopathologic features of pilocytic astrocytomas with FGFR1 alterations versus those harboring the more common BRAF mutations or fusions. Here we performed comprehensive genomic and epigenomic characterization on a diverse cohort of 30 LGNET with FGFR1 alterations. We identified that RGNT harbors a distinct epigenetic signature compared to other LGNET with FGFR1 alterations, and is uniquely characterized by FGFR1 kinase domain hotspot missense mutations in combination with either PIK3CA or PIK3R1 mutation, often with accompanying NF1 or PTPN11 mutation. In contrast, EVN harbors its own distinct epigenetic signature and is characterized by FGFR1-TACC1 fusion as the solitary pathogenic alteration. Additionally, DNT and PA are characterized by either kinase domain tandem duplication or hotspot missense mutations, occasionally with accompanying NF1 or PTPN11 mutation, but lacking the accompanying PIK3CA or PIK3R1 mutation that characterizes RGNT. The glial component of LGNET with FGFR1 alterations typically has a predominantly oligodendroglial morphology, and many of the pilocytic astrocytomas with FGFR1 alterations lack the biphasic pattern, piloid processes, and Rosenthal fibers that characterize pilocytic astrocytomas with BRAF mutation or fusion. Together, this analysis refines the classification and histopathologic spectrum of LGNET with FGFR1 alterations.

Comprehensive analysis of diverse low-grade neuroepithelial tumors with FGFR1 alterations reveals a distinct molecular signature of rosette-forming glioneuronal tumor

The FGFR1 gene encoding fibroblast growth factor receptor 1 has emerged as a frequently altered oncogene in the pathogenesis of multiple low-grade neuroepithelial tumor (LGNET) subtypes including pilocytic astrocytoma, dysembryoplastic neuroepithelial tumor (DNT), rosette-forming glioneuronal tumor (RGNT), and extraventricular neurocytoma (EVN). These activating FGFR1 alterations in LGNET can include tandem duplication of the exons encoding the intracellular tyrosine kinase domain, in-frame gene fusions most often with TACC1 as the partner, or hotspot missense mutations within the tyrosine kinase domain (either at p.N546 or p.K656). However, the specificity of these different FGFR1 events for the various LGNET subtypes and accompanying genetic alterations are not well defined. Here we performed comprehensive genomic and epigenomic characterization on a diverse cohort of 30 LGNET with FGFR1 alterations. We identified that RGNT harbors a distinct epigenetic signature compared to other LGNET with FGFR1 alterations, and is uniquely characterized by FGFR1 kinase domain hotspot missense mutations in combination with either PIK3CA or PIK3R1 mutation, often with accompanying NF1 or PTPN11 mutation. In contrast, EVN harbors its own distinct epigenetic signature and is characterized by FGFR1-TACC1 fusion as the solitary pathogenic alteration. Additionally, DNT and pilocytic astrocytoma are characterized by either kinase domain tandem duplication or hotspot missense mutations, occasionally with accompanying NF1 or PTPN11 mutation, but lacking the accompanying PIK3CA or PIK3R1 mutation that characterizes RGNT. The glial component of LGNET with FGFR1 alterations typically has a predominantly oligodendroglial morphology, and many of the pilocytic astrocytomas with FGFR1 alterations lack the biphasic pattern, piloid processes, and Rosenthal fibers that characterize pilocytic astrocytomas with BRAF mutation or fusion. Together, this analysis improves the classification and histopathologic stratification of LGNET with FGFR1 alterations.

Intramedullary tumours and tumour mimics

Spinal cord lesions are traditionally classified as either extradural or intradural extramedullary or of intramedullary origin. Intramedullary spinal cord tumours are histopathologically similar to cranial tumours with a diverse range of pathologies. Astrocytomas and ependymomas account for approximately 80% of all intramedullary tumours, with other primary and secondary lesions accounting for the remaining 20%. Magnetic resonance imaging is the preferred imaging modality for diagnosing and characterising spinal cord lesions; however, accurate characterisation of tumour histology can be challenging, and is further confounded by intramedullary non-neoplastic lesions, such as demyelinating vascular, inflammatory, infectious, or traumatic lesions. This review illustrates the spectrum of intramedullary tumours and tumour mimics with emphasis on the imaging findings.

P1000Aetiology and efficacy of atrial fibrillation ablation in young adults

Introduction

Little is known regarding the aetiology or outcome of atrial fibrillation (AF) occurring in young adults. This retrospective analysis was performed to explore the demographics and efficacy of AF ablation in this population.

Methods

Patients were included who had undergone ≥1 AF ablation under the age of 40 between 2006-2018. Recurrence was defined as return of either documented AF or previous symptoms for >30s following a 3-month blanking period. Initial exploratory co-variates were included in a univariate analysis and those terms with P-value of <0.1 were then used to generate a Cox proportional-hazards multivariate model.

Results

124 patients (33.6 ± 4.7 yrs, 77% men), initially presenting with paroxysmal AF (pAF; n = 97) or persistent AF (n = 27), underwent 175 AF ablation procedures. 22.6% (n = 28) also had atrial flutter. Time from symptom onset to first ablation was 50.7 ± 46.2 months. Relevant cardiovascular-related demographics were analysed: hypertension in 8.9% (n = 11); diabetes in 1.6% (n = 2); positive family history of AF in 12.9% (n = 16); and family history of sudden cardiac death in 2.4% (n = 3). Mean CHA2DS2-VASc score was 0.35. Of those patients with documented echocardiogram imaging (n = 91), 26.4% (n = 24) had LA dilatation and 6.6% (n = 6) had LV dysfunction. Patients with LA dilatation underwent more ablations (2.3 ± 0.3) compared to controls (1.5 ± 0.1; p < 0.001).

Ablation strategy was pulmonary vein isolation (PVI) only in 67.2% (n = 119), with additional ablation in the remaining: roof line in 18.9% (n = 33); cavotricuspid isthmus line in 13.1% (n = 23); mitral isthmus line in 2.3% (n = 4); superior vena cava isolation in 2.3% (n = 4); complex fractionated atrial electrograms in 14.9% (n = 26). Mean procedure time was 155 ± 41 min, mean ablation time was 1657 ± 991 s and mean fluoroscopy time was 32.6 ± 23.4 min. General anaesthesia was used in 43.4% (n = 76). Complications included femoral haematoma (n = 2), tamponade (n = 1) and pulmonary vein stenosis (n = 2).

90 days of follow-up was available for 137 procedures performed for pAF (n = 105) and persistent AF (n = 32). For pAF, overall recurrence was 61.9% for first ablations and 62.9% overall. Recurrence was 56.3% for persistent AF.

Factors significantly associated with increased AF recurrence in univariate analysis were

male gender (hazard ratio (HR) 2.3, 95% confidence interval (CI): 1.2-4.4, p = 0.011), hypertension (HR 0.5, CI: 0.2-1.1, p = 0.067), family history of sudden cardiac death (HR 6.8, CI: 1.6-29.0 , p = 0.010) and enlarged LA size (HR 2.2, CI: 1.3-3.6, p = 0.003). In multivariate analysis, the only significant predictor of poor outcome was enlarged LA size (HR 2.0, 95% CI: 1.2-3.5, p = 0.011).

Conclusions

Young patients with AF may have structurally abnormal hearts, and therefore do not only present with lone AF. LA size may be used as a predictor for success. Surveillance imaging may be useful to detect future structural change, which will be the subject of future prospective studies.

Abstract Figure. AF ablation recurrence in young adults

P1381Improved outcome in ablation of ventricular tachycardia in patients with structural heart disease under general anaesthetic

Background

Catheter ablation is an important adjunct to device implantation for secondary prevention of ventricular tachycardia (VT). However, several factors may influence the success of ablations in terms of long-term freedom from VT recurrence. A thus far little examined factor is the use of general anaesthetic (GA) versus conscious sedation during the procedure, which has been shown to improve outcomes in persistent atrial fibrillation (AF) ablation.

Methods

Patients with structural heart disease VT undergoing ablations from January 2015 to March 2019 were retrospectively followed up at a single centre. End points were recurrent VT or device therapy (shock or anti-tachycardia pacing) at one year. Hazard ratios (HR) were generated using a multivariate Cox-regression proportional hazards model including variables of age at ablation, sex, amiodarone use at time of ablation, scar age, left ventricular ejection fraction, use of GA, and diagnosis of: diabetes mellitus (DM), hypertension (HTN), renal impairment or AF.

Results

79 patients (74 male, mean age 68.2+/- 10.3 years) were included. A substrate-based strategy of late potential ablation was employed. 69 had ischaemic and 10 had non-ischaemic cardiomyopathy. Mean scar age was 13.8 +/- 9.8 years; EF was 40-50% in 27 patients, 30-40% in 26 and < 30% in 26. 37 patients had implantable cardioverter defibrillators and 30 had cardiac resynchronisation therapy (CRT) defibrillator devices, 1 had a CRT- pacemaker device and 4 had dual chamber pacemakers. Comorbidities were: DM (16), HTN (31), renal impairment (13), AF (31). 62 patients (79.5%) were on amiodarone at the time of ablation. Mean procedure duration was 234.8 +/- 44.5 min and mean radiofrequency energy application time was 2247 +/- 862 s. 61 were first procedures and 18 were repeat procedures. One patient suffered a complication of groin haematoma. 62 patients (78.5%) underwent VT ablation under GA and 17 (21.5%) under sedation of midazolam and fentanyl. Patient characteristics did not differ between groups. Significant factors which increased freedom from VT recurrence or device therapy were HTN (88.9% vs 59.4%, HR 0.72, 95% confidence interval (CI): 0.007-0.75, p= 0.028), amiodarone treatment (50.0% vs 76.3%, HR 0.036, 95% CI: 0.003-0.404, p = 0.036) and ablation under GA rather than sedation (50.0% vs 75.0%, HR 0.055, 95% CI: 0.006-0.495, p = 0.01) (Fig 1).

Conclusions

In patients with structural heart disease undergoing VT ablation, outcomes are improved with the use of GA over conscious sedation.

Abstract Figure 1

Pediatric bithalamic gliomas have a distinct epigenetic signature and frequent EGFR exon 20 insertions resulting in potential sensitivity to targeted kinase inhibition

Brain tumors are the most common solid tumors of childhood, and the genetic drivers and optimal therapeutic strategies for many of the different subtypes remain unknown. Here, we identify that bithalamic gliomas harbor frequent mutations in the EGFR oncogene, only rare histone H3 mutation (in contrast to their unilateral counterparts), and a distinct genome-wide DNA methylation profile compared to all other glioma subtypes studied to date. These EGFR mutations are either small in-frame insertions within exon 20 (intracellular tyrosine kinase domain) or missense mutations within exon 7 (extracellular ligand-binding domain) that occur in the absence of accompanying gene amplification. We find these EGFR mutations are oncogenic in primary astrocyte models and confer sensitivity to specific tyrosine kinase inhibitors dependent on location within the kinase domain or extracellular domain. We initiated treatment with targeted kinase inhibitors in four children whose tumors harbor EGFR mutations with encouraging results. This study identifies a promising genomically-tailored therapeutic strategy for bithalamic gliomas, a lethal and genetically distinct brain tumor of childhood.

0040 Relationship Between Inflammatory Markers and Sleep in Healthy Adolescents

Introduction

Multiple studies in different countries show a trend of adolescents having insufficient sleep. Review of literature strongly suggests role of cytokines in sleep regulation. Different inflammatory markers like tumor necrosis factor (TNF)α, C-reactive protein (CRP) and interleukins (IL) are sleep regulatory substances. Most of the studies showing relation between cytokines and sleep are seen in adults. In our study, we were interested in finding the relationship between sleep quality and inflammatory markers in healthy adolescents.

Methods

Twenty eight female and male, African American and White, healthy adolescents aged 15–18 completed the study. Sleep quality was measured using the Pediatric Sleep Questionnaires (PSQ), including snoring, daytime sleepiness and hyperactive behavior. Blood sample was collected from each participant for measuring the inflammatory factors.

Results

Partial Pearson correlation analysis showed that global PSQ score and hyperactive behavior were significantly correlated with TNF α (r=0.37 for both). Snoring was significantly correlated with leptin, CRP and IL-6 in healthy adolescents. No other correlations were observed.

Conclusion

Consistent with findings in adults, we have observed an association between inflammatory markers and poor sleep in healthy adolescents. Our findings suggest the importance to improve sleep quality in adolescents for better health outcomes.

Support

None of the authors have any conflict of interest. This research was supported by awards, P30DK056336 and P30DK079626, from the National Institute of Diabetes And Digestive And Kidney Diseases to Nutrition Obesity Research Center and Diabetes Research Center, respectively, at the University of Alabama at Birmingham.

Louis EK, Schwarz CG, Bradley BF, Lowe VJ, Przybelski SA, Reddy A, Mielke MM, Knopman DS, Petersen RC, Jack CR, Vemuri P. 0355 Neurobiological Correlates of Sleepiness in Middle Aged and Older Adults: A FDG-PET Study

Introduction

Sleepiness has been associated with functional and cognitive decline, and may present with excessive daytime sleepiness (EDS) and/or increased sleep duration. We investigated whether sleepiness and changes in sleep patterns are associated with FDG-PET levels in wake-promoting regions.

Methods

From the Mayo Clinic Study of Aging cohort, we identified 373 cognitively-unimpaired middle-aged and older adults (mean +/- s.d. 66.1 +/- 13.2 yo) who underwent FDG-PET. EDS was defined as ESS score >=10. Changes in sleep patterns (sleeping more, less, or no change) were assessed using question #16 of the Beck Depression Inventory-2. We used probabilistic maps to create regions of interest (ROIs): the locus coeruleus (LC), posterior lateral hypothalamus (PLH), and the basal forebrain divided in 1) medial septum/diagonal band of Broca (MS/DB) and 2) nucleus basalis of Meynert (nbM). FDG-PET levels were referenced to the pons (SUVR). In this cross-sectional analysis, we fit linear models to assess the association between EDS and changes in sleeping patterns with FDG SUVR in in each ROI, while controlling for age, sex, education, BMI, witnessed apneas, and cardiovascular risk factors.

Results

10.5% had EDS, 15% reported sleeping more and 21% reported sleeping less than usual. 30.7% of participants with EDS reported sleeping more, 25.6% less, and 43.5% the same. EDS was associated with an elevation in FDG-PET SUVR in the MS/DB region (.035 [95% CI .008; .063], p=.012), while sleeping more was associated with a decrease in FDG-PET SUVR in the same region (-.027 [95%CI -.052; -.002], p=.036). Sleeping less was associated with an increase in FDG-PET SUVR in the PLH (.021 [95% CI .005; .03], p=.019). No associations were found in other ROIs.

Conclusion

Our results suggest that sleepiness and changes in sleep patterns in cognitively-unimpaired middle-aged and older adults were associated with measurable metabolic changes in areas of the brain involved in sleep and wakefulness. Further research should clarify whether these findings could represent different phenotypes of sleepiness with potential diagnostic and prognostic implications.

Support

NIA/NIH

Deep venous thrombosis manifestation of common femoral vein leiomyoma

Deep vein thrombosis is a common clinical condition, with well-known risk factors. An unusual case of venous leiomyoma manifesting as a deep vein thrombosis in the left femoral vein of a 55-year-old man was managed successfully at our institution with anticoagulation, en-bloc excision and reconstruction of the femoral vein with spiral vein graft.

Safety of hospital discharge before return of bowel function after elective colorectal surgery

BACKGROUND

Ileus is common after colorectal surgery and is associated with an increased risk of postoperative complications. Identifying features of normal bowel recovery and the appropriateness for hospital discharge is challenging. This study explored the safety of hospital discharge before the return of bowel function.

METHODS

A prospective, multicentre cohort study was undertaken across an international collaborative network. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The main outcome of interest was readmission to hospital within 30 days of surgery. The impact of discharge timing according to the return of bowel function was explored using multivariable regression analysis. Other outcomes were postoperative complications within 30 days of surgery, measured using the Clavien-Dindo classification system.

RESULTS

A total of 3288 patients were included in the analysis, of whom 301 (9·2 per cent) were discharged before the return of bowel function. The median duration of hospital stay for patients discharged before and after return of bowel function was 5 (i.q.r. 4-7) and 7 (6-8) days respectively (P < 0·001). There were no significant differences in rates of readmission between these groups (6·6 versus 8·0 per cent; P = 0·499), and this remained the case after multivariable adjustment for baseline differences (odds ratio 0·90, 95 per cent c.i. 0·55 to 1·46; P = 0·659). Rates of postoperative complications were also similar in those discharged before versus after return of bowel function (minor: 34·7 versus 39·5 per cent; major 3·3 versus 3·4 per cent; P = 0·110).

CONCLUSION

Discharge before return of bowel function after elective colorectal surgery appears to be safe in appropriately selected patients.

Safety and efficacy of non-steroidal anti-inflammatory drugs to reduce ileus after colorectal surgery

BACKGROUND

Ileus is common after elective colorectal surgery, and is associated with increased adverse events and prolonged hospital stay. The aim was to assess the role of non-steroidal anti-inflammatory drugs (NSAIDs) for reducing ileus after surgery.

METHODS

A prospective multicentre cohort study was delivered by an international, student- and trainee-led collaborative group. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The primary outcome was time to gastrointestinal recovery, measured using a composite measure of bowel function and tolerance to oral intake. The impact of NSAIDs was explored using Cox regression analyses, including the results of a centre-specific survey of compliance to enhanced recovery principles. Secondary safety outcomes included anastomotic leak rate and acute kidney injury.

RESULTS

A total of 4164 patients were included, with a median age of 68 (i.q.r. 57-75) years (54·9 per cent men). Some 1153 (27·7 per cent) received NSAIDs on postoperative days 1-3, of whom 1061 (92·0 per cent) received non-selective cyclo-oxygenase inhibitors. After adjustment for baseline differences, the mean time to gastrointestinal recovery did not differ significantly between patients who received NSAIDs and those who did not (4·6 versus 4·8 days; hazard ratio 1·04, 95 per cent c.i. 0·96 to 1·12; P = 0·360). There were no significant differences in anastomotic leak rate (5·4 versus 4·6 per cent; P = 0·349) or acute kidney injury (14·3 versus 13·8 per cent; P = 0·666) between the groups. Significantly fewer patients receiving NSAIDs required strong opioid analgesia (35·3 versus 56·7 per cent; P < 0·001).

CONCLUSION

NSAIDs did not reduce the time for gastrointestinal recovery after colorectal surgery, but they were safe and associated with reduced postoperative opioid requirement.

A near-peer regional surgical teaching programme designed by medical students, delivered by junior doctors

BACKGROUND

Near-peer teaching initiatives has been shown to be a highly successful method of improving student learning. There has been little data on surgical teaching initiatives of this kind and little data to show if this improves student confidence in surgical topics. This study was designed to show whether a regional surgical teaching programme, delivered by junior doctors, improves confidence levels of students prior to their final examinations.

METHOD

Final year medical students were invited from four hospitals in the Northern deanery of England to participate in a voluntary surgical teaching day. Junior doctors were then recruited to present on various surgical topics based on their own knowledge and experience of finals examinations and working on the wards. A pre and post-course questionnaire was designed, validated and distributed to the students to assess their confidence on a five-point Likert scale of 1-5 (1- most confidence, 5- least confidence) levels in each of the 11 chosen topics. Other variables were also measured relating to the topics including visual material, enthusiasm, content relevance and communication.

RESULTS

53 students completed the questionnaire (n = 53). There were 31 females and 22 males with a mean age of 24.7. A mean level of confidence of 2.7 pre-course and 1.6 post-course showed an increase in confidence by 68.8%. All eleven topics covered showed improvement in confidence. General Surgical Principles showed the lowest improvement in confidence from 2.683 to 1.917 (p = <0.001) compared to endocrine which showed the maximum increased in confidence from 3.650 to 1.694 (p = <0.0001). Orthopedics showed an increased in confidence from 3.010 to 1.62 (p = <0.0001).

CONCLUSION

Near-peer education designed by medical students and delivered by junior doctors is an effective way for improving confidence levels and test results prior to finals examination and is also valuable for junior doctors.

A C19MC-LIN28A-MYCN Oncogenic Circuit Driven by Hijacked Super-enhancers Is a Distinct Therapeutic Vulnerability in ETMRs: A Lethal Brain Tumor

Embryonal tumors with multilayered rosettes (ETMRs) are highly lethal infant brain cancers with characteristic amplification of Chr19q13.41 miRNA cluster (C19MC) and enrichment of pluripotency factor LIN28A. Here we investigated C19MC oncogenic mechanisms and discovered a C19MC-LIN28A-MYCN circuit fueled by multiple complex regulatory loops including an MYCN core transcriptional network and super-enhancers resulting from long-range MYCN DNA interactions and C19MC gene fusions. Our data show that this powerful oncogenic circuit, which entraps an early neural lineage network, is potently abrogated by bromodomain inhibitor JQ1, leading to ETMR cell death.