Can quantifying the extent of 'high grade' features help explain prognostic variability in anaplastic astrocytoma?

PURPOSE

Both phenotypic and genotypic variations now underpin glioma classification, thus helping to more accurately guide their clinical management. However, WHO Grade III anaplastic astrocytoma (AA) remains an unpredictable, heterogeneous entity; displaying a variable prognosis, clinical course and treatment response. This study aims to examine whether additional tumour characteristics influence either overall survival (OS) or 3-year survival in AA.

MATERIALS AND METHODS

Data were collected on all newly diagnosed cases of AA between 2003 and 2014, followed up for a minimum of 3 years. Molecular information was obtained from case records and if missing, was re-analysed. Histological slides were independently examined for Ki-67 proliferation index, cellularity and number of mitotic figures. Kaplan-Meier and Cox regression analyses were used to assess OS.

RESULTS

In total, 50 cases were included with a median OS of 14.5 months (range: 1-150 months). Cumulative 3-year survival was 31.5%. Median age was 50 years (range: 24 - 77). Age, IDH1 mutation status, lobar location, oncological therapy and surgical resection were significant independent prognostic indicators for OS. In cases demonstrating an OS ≥ 3 years (n = 15), Ki-67 index, number of mitotic figures and percentage areas of 'high cellularity' were significantly reduced, i.e. more characteristic of lower-grade/WHO Grade II glioma.

CONCLUSIONS

IDH1 status, age, treatment and location remain the most significant prognostic indicators for patients with AA. However, Ki-67 index, mitotic figures and cellularity may help identify AA cases more likely to survive < 3 years, i.e. AA cases more similar to glioblastoma and those cases more likely to survive > 3 years, i.e. more similar to a low-grade glioma.

IDHwt glioblastomas can be stratified by their transcriptional response to standard treatment, with implications for targeted therapy

BACKGROUND

Glioblastoma (GBM) brain tumors lacking IDH1 mutations (IDHwt) have the worst prognosis of all brain neoplasms. Patients receive surgery and chemoradiotherapy but tumors almost always fatally recur.

RESULTS

Using RNA sequencing data from 107 pairs of pre- and post-standard treatment locally recurrent IDHwt GBM tumors, we identify two responder subtypes based on longitudinal changes in gene expression. In two thirds of patients, a specific subset of genes is upregulated from primary to recurrence (Up responders), and in one third, the same genes are downregulated (Down responders), specifically in neoplastic cells. Characterization of the responder subtypes indicates subtype-specific adaptive treatment resistance mechanisms that are associated with distinct changes in the tumor microenvironment. In Up responders, recurrent tumors are enriched in quiescent proneural GBM stem cells and differentiated neoplastic cells, with increased interaction with the surrounding normal brain and neurotransmitter signaling, whereas Down responders commonly undergo mesenchymal transition. ChIP-sequencing data from longitudinal GBM tumors suggests that the observed transcriptional reprogramming could be driven by Polycomb-based chromatin remodeling rather than DNA methylation.

CONCLUSIONS

We show that the responder subtype is cancer-cell intrinsic, recapitulated in in vitro GBM cell models, and influenced by the presence of the tumor microenvironment. Stratifying GBM tumors by responder subtype may lead to more effective treatment.

Imaging Spectrum of the Developing Glioblastoma: A Cross-Sectional Observation Study

Glioblastoma (GBM) has the typical radiological appearance (TRA) of a centrally necrotic, peripherally enhancing tumor with surrounding edema. The objective of this study was to determine whether the developing GBM displays a spectrum of imaging changes detectable on routine clinical imaging prior to TRA GBM. Patients with pre-operative imaging diagnosed with GBM (1 January 2014-31 March 2022) were identified from a neuroscience center. The imaging was reviewed by an experienced neuroradiologist. Imaging patterns preceding TRA GBM were analyzed. A total of 76 out of 555 (14%) patients had imaging preceding TRA GBM, 57 had solitary lesions, and 19 had multiple lesions (total = 84 lesions). Here, 83% of the lesions had cortical or cortical/subcortical locations. The earliest imaging features for 84 lesions were T2 hyperintensity/CT low density (n = 18), CT hyperdensity (n = 51), and T2 iso-intensity (n = 15). Lesions initially showing T2 hyperintensity/CT low density later showed T2 iso-intensity. When CT and MRI were available, all CT hyperdense lesions showed T2 iso-intensity, reduced diffusivity, and the following enhancement patterns: nodular 35%, solid 29%, none 26%, and patchy peripheral 10%. The mean time to develop TRA GBM from T2 hyperintensity was 140 days and from CT hyperdensity was 69 days. This research suggests that the developing GBM shows a spectrum of imaging features, progressing through T2 hyperintensity to CT hyperdensity, T2 iso-intensity, reduced diffusivity, and variable enhancement to TRA GBM. Red flags for non-TRA GBM lesions are cortical/subcortical CT hyperdense/T2 iso-intense/low ADC. Future research correlating this imaging spectrum with pathophysiology may provide insight into GBM growth patterns.

GBMdeconvoluteR accurately infers proportions of neoplastic and immune cell populations from bulk glioblastoma transcriptomics data

BACKGROUND

Characterizing and quantifying cell types within glioblastoma (GBM) tumors at scale will facilitate a better understanding of the association between the cellular landscape and tumor phenotypes or clinical correlates. We aimed to develop a tool that deconvolutes immune and neoplastic cells within the GBM tumor microenvironment from bulk RNA sequencing data.

METHODS

We developed an IDH wild-type (IDHwt) GBM-specific single immune cell reference consisting of B cells, T-cells, NK-cells, microglia, tumor associated macrophages, monocytes, mast and DC cells. We used this alongside an existing neoplastic single cell-type reference for astrocyte-like, oligodendrocyte- and neuronal progenitor-like and mesenchymal GBM cancer cells to create both marker and gene signature matrix-based deconvolution tools. We applied single-cell resolution imaging mass cytometry (IMC) to ten IDHwt GBM samples, five paired primary and recurrent tumors, to determine which deconvolution approach performed best.

RESULTS

Marker-based deconvolution using GBM-tissue specific markers was most accurate for both immune cells and cancer cells, so we packaged this approach as GBMdeconvoluteR. We applied GBMdeconvoluteR to bulk GBM RNAseq data from The Cancer Genome Atlas and recapitulated recent findings from multi-omics single cell studies with regards associations between mesenchymal GBM cancer cells and both lymphoid and myeloid cells. Furthermore, we expanded upon this to show that these associations are stronger in patients with worse prognosis.

CONCLUSIONS

GBMdeconvoluteR accurately quantifies immune and neoplastic cell proportions in IDHwt GBM bulk RNA sequencing data and is accessible here: https://gbmdeconvoluter.leeds.ac.uk.

Do animal models of brain tumors replicate human peritumoral edema? a systematic literature search

INTRODUCTION

Brain tumors cause morbidity and mortality in part through peritumoral brain edema. The current main treatment for peritumoral brain edema are corticosteroids. Due to the increased recognition of their side-effect profile, there is growing interest in finding alternatives to steroids but there is little formal study of animal models of peritumoral brain edema. This study aims to summarize the available literature.

METHODS

A systematic search was undertaken of 5 literature databases (Medline, Embase, CINAHL, PubMed and the Cochrane Library). The generic strategy was to search for various terms associated with "brain tumors", "brain edema" and "animal models".

RESULTS

We identified 603 reports, of which 112 were identified as relevant for full text analysis that studied 114 peritumoral brain edema animal models. We found significant heterogeneity in the species and strain of tumor-bearing animals, tumor implantation method and edema assessment. Most models did not produce appreciable brain edema and did not test for observable manifestations thereof.

CONCLUSION

No animal model currently exists that enable the investigation of novel candidates for the treatment of peritumoral brain edema. With current interest in alternative treatments for peritumoral brain edema, there is an unmet need for clinically relevant animal models.

IDHwt Glioblastomas Show Opposing Resistance Mechanisms Across Patients in Response to Standard Treatment

AIMS

Glioblastoma (GBM) is the most common primary malignant brain tumour in adults. Despite aggressive treatment, a resistant tumour recurs in practically all patients. We therefore aimed to better understand the mechanisms driving this treatment resistance through investigating changes in gene expression across pairs of primary and recurrent GBM tumours.

METHOD

We generated or acquired bulk tumour RNA sequencing data for primary and first recurrent tumours from 107 patients who received standard treatment. Differential expression analysis between primary and recurrent samples found that the most dysregulated genes were involved in neurodevelopment and neurodifferentiation. We therefore used a publicly available ChIP-seq database to identify DNA binding factors for which binding sites are enriched in the promotors of genes with the largest expression changes from primary to recurrent.

RESULTS

Jumonji and AT-Rich Interacting Domain 2 (JARID2) was the most strongly enriched for binding to promotors of dysregulated genes. 65 patients showed an up-regulation and 42 showed a down-regulation of genes bound by this protein. The same set of JARID2 bound genes were found to be dysregulated in each direction, and correlated with the largest source of variation between samples in their response to treatment. Further enrichment analyses indicated that ‘Up’ responders may resist treatment through reduced proliferation and increased interaction with the tumour microenvironment, whereas ‘Down’ responders instead rely on a shift to mesenchymal cell states.

CONCLUSION

These results indicate that GBM tumours can be split into two subtypes that transcriptionally reprogramme in different directions through treatment and may benefit from different treatment approaches.

Developing consensus in Histopathology: the role of the Delphi method

The Delphi method is a well-established research tool, used for consensus building across a number of fields. Despite its widespread use, and popularity in many medical specialities, there is a paucity of literature on the use of the Delphi method in Histopathology. This literature review seeks to critique the Delphi methodology and explore its potential applications to histopathology-based clinical and research questions. We review those published studies that have utilized the Delphi methodology in Histopathology settings and specifically outline the advantages and limitations of this technique, highlighting situations where its application can be most effective.

OA42 Evaluating the effects on a clinical service of introducing ultrasound for diagnosis of giant cell arteritis using Lean methodology

Background/Aims

In our trust, patients with suspected giant cell arteritis (GCA) were promptly started on high-dose prednisolone. However, until 2019, patients were waiting on average 28.5 days (median) for confirmation of diagnostic decision, which was mostly due to the time taken for temporal artery biopsy (TAB) to be performed and reported. We have made two major changes to our pathway: firstly (Jan 2019) adding temporal artery ultrasound (TAUS), and secondly (Mar 2020), routing GP referrals through our Primary Care Access Line (PCAL) to an allocated rheumatology registrar based at the same site as the TAUS. We used Lean methodology to pre-specify metrics to evaluate our pathway.

Aim and Purpose: To assess changes over time across our five prespecified domains: delivery, quality, service, morale and cost.

Methods

We defined lead time as median time between entry to pathway and diagnostic confirmation. This was our delivery domain. We defined treatment for GCA as clinical diagnosis plus at least 6 months of treatment with “GCA-dose” steroids. Quality was measured for patients treated as GCA as the percentage with a positive confirmatory test; and for patients not treated as GCA as the cumulative prednisolone dose received for suspected GCA. Service and morale were assessed from patient and staff feedback, respectively. Cost was assessed via the patient-level costings team using standard NHS tariffs. We plotted a run chart by month and significant shift in delivery or quality was defined as six consecutive monthly values below the baseline median.

Results

TAUS was performed a median of 2.5 days from referral. Agreement between TAB and TAUS results was good. The run chart showed a significant shift in our delivery. Lead time fell from 28.7 days to 19.2 days after introduction of ultrasound, and further down to 7.7 days after the utilisation of PCAL. A significant shift was also seen in quality metrics. Proportion of GCA with positive TAB/TAUS increased from 29% to 56.3% following the introduction of TAUS, and further to 75% on the utilisation of PCAL. The total mean prednisolone dose for patient without GCA fell from 1.335g to 0.439g after introducing TAUS, and down to 0.139g after introduction of PCAL. Within costs, average per-patient costs of TAB/TAUS declined from £1004/patient to £718/patient to £378/patient. However, total GCA pathway referrals increased from 6/month to 10/month to 24/month, increasing overall costs.

Staff and patient feedback (service, morale) were overall positive, but revealed the need for further improvements to manage the additional complexity and volume.

Conclusion

Lean methodology identified multiple metrics for evaluating the impact of TAUS and PCAL on our service. We have seen an improvement in delivery and quality. Measuring costs, morale and service helped identify unintended consequences and target further improvement.

Disclosure

T. Rajeswaran: None. A. Barr: None. V. Bassi: None. A. Chakrabarty: None. A. Cracknell: None. R. Darwood: None. S. Dass: None. S. Farrell: None. J. Hunter: None. T. Mitchell: None. J. Parvin: None. B. Sarker: None. I. Simmons: None. K. Sinclair: None. K. Smith: None. A. Sweeting: None. R. Tue: None. M. Troxler: None. R. Wakefield: None. S.L. Mackie: Consultancies; consultancy for Roche, Sanofi, AstraZeneca, Abbvie on behalf of her institution. Other; support from Roche to attend EULAR2019.

Comparative evaluation of bond strength of resin cements with and without 10-methacryloyloxydecyl dihydrogen phosphate (mdp) to zirconia and effect of thermocycling on bond strength – An in vitro study

Background

To compare bond strength of resin cements with and without 10-Methacryloyloxydecyl Dihydrogen Phosphate (MDP) to zirconia and evaluate effect of thermocycling on bond strength.

Material and Methods

Standardised test specimens were fabricated as per ADA specification 131. Each Zirconia specimen was mounted in autopolymerzing acrylic resin material. The specimens were divided into 2 groups: Group 1 – specimens bonded with resin cement containing 10-MDP and Group II - specimens bonded with resin cement without 10-MDP. Forty samples of resin cement cylinders were prepared with dimensions of 6mm height and 4mm diameter in line with ADA specification 27 were cured onto the zirconia surface of 10mm x10mm x5mm using customised moulds. Specimens from each cement group were further divided into 2 subgroups: Subgroup A – Specimens that were not thermocycled and Subgroup B – Specimens that were thermocycled. Specimens were then subjected to tensile bond testing by using a Universal testing machine, the data were analysed using independent sample t test for bond strength and paired t test for effect of thermocycling. Statistical analysis used: Data was subjected to normalcy test (Shapiro-wilk test). Data showed normal distribution. Hence parametric test paired t test were applied.

Results

Paired t test revealed that the thermocycling affected the bond strength to zirconia. The highest bond strength was achieved for the resin cement with 10-MDP before thermocycling, whereas the lowest bond strength values were recorded for resin cement without 10-MDP after thermocycling.

Conclusions

Resin cement with 10-MDP showed superior bond strength to Zirconia than resin cement without 10-MDP. Adhesive failure was predominant at Zirconia and resin cement interface. Thermocycling had a significant effect on the bond strength of resin cements to zirconia, showing decreased bond strength.

Key words:10-MDP, Tensile Strength, Zirconia.

PATH-47. THE 2016 WHO CLASSIFICATION AND IT'S CLINICAL IMPACT: THE LEEDS TEACHING HOSPITALS NHS TRUST EXPERIENCE

INTRODUCTION

In 2016 the WHO Classification of Tumours of the Central Nervous System was updated to include molecular testing, in addition to the previous standard histological methods; producing a final integrated diagnosis. Although molecular information can guide treatment and aid in prognostication, it adds a significant workload to pathology and genetic testing services. Delayed diagnosis can also add anxiety to patients, at an already traumatic time. AIMS: To determine if final integrated diagnoses, for patients undergoing neurosurgery for CNS tumours, is being provided in an appropriate time frame, and whether it changes clinical management.

METHODS

All patients &gt;16 years at the time of surgery with a histopathologically-confirmed CNS tumour were identified from 2016-2020. A retrospective analysis of the time taken to produce an integrated histological diagnosis took place, using the date of surgery and date of verified final integrated report being the first and last data points respectively. Data were collected by accessing electronic and paper health records, and local databases. Changes in clinical management between the initial histology result and the final integrated diagnosis were classified as no change or a major change.

RESULTS

1390 surgical procedures for CNS pathology were identified between 2016-2020, producing 361 final integrated diagnosis reports. 64 (18%) of these reports resulted in a major change in clinical management when compared to the initial histology report. The turn-around time for initial histology from date of surgery was a mean of 9 days and a mean of 34 days for the final integrated diagnosis.

CONCLUSIONS

The integrated diagnosis is essential for providing the gold standard of treatment for patients, although for the majority of patients it does not change their clinical management. Further study and discussion is required about the role of the final integrated diagnosis in the management of patients with CNS tumours.

Determining the real site of peroneal nerve injury with knee dislocation: Earlierier is easier

Common peroneal nerve (CPN) injury is a recognised complication of traumatic knee dislocation with a direct association between the degree of ligamentous injury and the degree of CPN injury. It is essential explore and repair these injuries in good time to reduce morbidity. Often exploration only involves the portion of this nerve associated with the joint as it courses around the fibular head. However, a recent case highlighted the importance of proximal exploration to its branching point from the sciatic nerve, a known point of fragility, even if other defects have been identified.

Correction to: Different aspects of Alzheimer's disease-related amyloid β-peptide pathology and their relationship to amyloid positron emission tomography imaging and dementia

An amendment to this paper has been published and can be accessed via the original article.

DNA methylation-based profiling for paediatric CNS tumour diagnosis and treatment: a population-based study

BACKGROUND

Marked variation exists in the use of genomic data in tumour diagnosis, and optimal integration with conventional diagnostic technology remains uncertain despite several studies reporting improved diagnostic accuracy, selection for targeted treatments, and stratification for trials. Our aim was to assess the added value of molecular profiling in routine clinical practice and the impact on conventional and experimental treatments.

METHODS

This population-based study assessed the diagnostic and clinical use of DNA methylation-based profiling in childhood CNS tumours using two large national cohorts in the UK. In the diagnostic cohort-which included routinely diagnosed CNS tumours between Sept 1, 2016, and Sept 1, 2018-we assessed how the methylation profile altered or refined diagnosis in routine clinical practice and estimated how this would affect standard patient management. For the archival cohort of diagnostically difficult cases, we established how many cases could be solved using modern standard pathology, how many could only be solved using the methylation profile, and how many remained unsolvable.

FINDINGS

Of 484 patients younger than 20 years with CNS tumours, 306 had DNA methylation arrays requested by the neuropathologist and were included in the diagnostic cohort. Molecular profiling added a unique contribution to clinical diagnosis in 107 (35%; 95% CI 30-40) of 306 cases in routine diagnostic practice-providing additional molecular subtyping data in 99 cases, amended the final diagnosis in five cases, and making potentially significant predictions in three cases. We estimated that it could change conventional management in 11 (4%; 95% CI 2-6) of 306 patients. Among 195 historically difficult-to-diagnose tumours in the archival cohort, 99 (51%) could be diagnosed using standard methods, with the addition of methylation profiling solving a further 34 (17%) cases. The remaining 62 (32%) cases were unresolved despite specialist pathology and methylation profiling.

INTERPRETATION

Together, these data provide estimates of the impact that could be expected from routine implementation of genomic profiling into clinical practice, and indicate limitations where additional techniques will be required. We conclude that DNA methylation arrays are a useful diagnostic adjunct for childhood CNS tumours.

FUNDING

The Brain Tumour Charity, Children with Cancer UK, Great Ormond Street Hospital Children's Charity, Olivia Hodson Cancer Fund, Cancer Research UK, and the National Institute of Health Research.

PRIMARY PIGMENTED NODULAR ADRENOCORTICAL DISEASE (PPNAD) PRESENTING AS CUSHING SYNDROME IN A CHILD AND REVIEW OF LITERATURE

Cushing syndrome in the paediatric age group is very difficult to diagnose due to atypical presenting features in children. Primary pigmented nodular adrenocortical disease (PPNAD) is a rare cause of ACTH-independent Cushing syndrome in children and it has characteristic gross and microscopic pathologic features. We report a case of PPNAD in a 16-year-old boy who was evaluated in our hospital with chief complaints of poor height velocity and rapid weight gain for 2-3 years before presentation. Proper evaluation showed ACTH-independent Cushing syndrome with normal imaging. Total bilateral adrenalectomy was performed followed by hormones replacement. 6 months after surgery, significant acceleration of height velocity was noticed. Patient also lost body weight and developed secondary sexual characteristics.

Longitudinal molecular trajectories of diffuse glioma in adults

The evolutionary processes that drive universal therapeutic resistance in adult patients with diffuse glioma remain unclear1,2. Here we analysed temporally separated DNA-sequencing data and matched clinical annotation from 222 adult patients with glioma. By analysing mutations and copy numbers across the three major subtypes of diffuse glioma, we found that driver genes detected at the initial stage of disease were retained at recurrence, whereas there was little evidence of recurrence-specific gene alterations. Treatment with alkylating agents resulted in a hypermutator phenotype at different rates across the glioma subtypes, and hypermutation was not associated with differences in overall survival. Acquired aneuploidy was frequently detected in recurrent gliomas and was characterized by IDH mutation but without co-deletion of chromosome arms 1p/19q, and further converged with acquired alterations in the cell cycle and poor outcomes. The clonal architecture of each tumour remained similar over time, but the presence of subclonal selection was associated with decreased survival. Finally, there were no differences in the levels of immunoediting between initial and recurrent gliomas. Collectively, our results suggest that the strongest selective pressures occur during early glioma development and that current therapies shape this evolution in a largely stochastic manner.

Different aspects of Alzheimer's disease-related amyloid β-peptide pathology and their relationship to amyloid positron emission tomography imaging and dementia

Alzheimer’s disease (AD)-related amyloid β-peptide (Aβ) pathology in the form of amyloid plaques and cerebral amyloid angiopathy (CAA) spreads in its topographical distribution, increases in quantity, and undergoes qualitative changes in its composition of modified Aβ species throughout the pathogenesis of AD. It is not clear which of these aspects of Aβ pathology contribute to AD progression and to what extent amyloid positron emission tomography (PET) reflects each of these aspects. To address these questions three cohorts of human autopsy cases (in total n = 271) were neuropathologically and biochemically examined for the topographical distribution of Aβ pathology (plaques and CAA), its quantity and its composition. These parameters were compared with neurofibrillary tangle (NFT) and neuritic plaque pathology, the degree of dementia and the results from [¹⁸F]flutemetamol amyloid PET imaging in cohort 3. All three aspects of Aβ pathology correlated with one another, the estimation of Aβ pathology by [¹⁸F]flutemetamol PET, AD-related NFT pathology, neuritic plaques, and with the degree of dementia. These results show that one aspect of Aβ pathology can be used to predict the other two, and correlates well with the development of dementia, advancing NFT and neuritic plaque pathology. Moreover, amyloid PET estimates all three aspects of Aβ pathology in-vivo. Accordingly, amyloid PET-based estimates for staging of amyloid pathology indicate the progression status of amyloid pathology in general and, in doing so, also of AD pathology. Only 7.75% of our cases deviated from this general association.

Chromatin remodelling to facilitate treatment resistance in glioblastoma

Recent findings from our group, and the wider community, show that standard treatment does not impose an apparent bottleneck on the clonal evolution of adult glioblastoma (GBM), implying a lack of direct therapeutic opportunity. This does not negate the possibility that multiple treatment-resistance mechanisms co-exist in tumours, repeated across patients, making a combination of targeted therapies a potentially effective approach. We investigated whether treatment resistance may be driven by selection of cellular properties conferred above the level of the genome. Differential expression analysis was performed on 23 pairs of primary and recurrent tumours from patients who received standard treatment and had a local recurrence treated by surgery and second line chemotherapy. This revealed a treatment-induced shift in cell states linked to normal neurodevelopment. The latter is orchestrated by cascades of transcription factors. We, therefore, applied a bespoke gene set enrichment analysis to our paired expression data to investigate whether any factors were implicated in co-regulation of the genes that were altered through therapy. This identified a specific chromatin remodelling machinery, instrumental in normal neurogenesis. We validated our results in an independent cohort of 22 paired GBM samples. Our results suggest that the chromatin remodelling machinery is responsible for determining transcriptional hierarchies in GBM, shown elsewhere to have different treatment sensitivities such that their relative abundances are altered through treatment.

OS9.5 Evidence that adult glioblastoma adapts to standard therapy though chromatin remodeling

BACKGROUND

Glioblastoma (GBM) tumours recur following standard treatment in almost all cases. We use ‘omics technologies to simultaneously profile pairs of primary and matched recurrent GBM to specifically identify and characterise the cells that resisted treatment, with the aim of determining how to more effectively kill them.

MATERIAL AND METHODS

We have analysed high coverage RNAseq data from pairs of GBM tumours: primary de novo tumour and matched local recurrence from patients that underwent standard therapy. Our original cohort constituted 23 pairs and our validation cohort was an additional 22 pairs. We also cultured two plates of spheroids directly from a patient’s GBM, treating one with radiation and temozolomide. We monitored growth and captured and sequenced RNA from single cells at two time-points: one week post-treatment when the deviation between untreated and treated spheroid growth curves was most pronounced; and three weeks post-treatment when the growth rate of treated spheroids had recovered. We investigated differential gene expression between primary and recurrent pairs, and single cells pre- and post-treatment, and performed a bespoke per patient gene set enrichment analysis.

RESULTS

Differential gene expression analysis in 23 tumour pairs indicated a treatment-induced shift in cell states linked to normal neurogenesis and prompted us to develop a novel gene set enrichment analysis approach to identify gene regulatory factors that may orchestrate such a shift. This revealed the significant and universal dysregulation of genes, through therapy, that are targeted by a specific chromatin remodeling machinery. This finding was validated in an independent cohort of 22 further GBM pairs. To understand the therapeutic potential of this finding we must determine whether genes are dysregulated through therapy owing to a) their fixed expression in inherently treatment resistance cells in the primary tumour which get selected during therapy to increase the signal of that profile, or b) changes in expression during the process of cells acquiring treatment resistance. To inspect this, we analysed single cell gene expression data from GBM spheroids pre- and post-treatment. We found that there was significant dysregulation of the genes associated with the chromatin remodeling complex but only at the three-week post-treatment time-point.

CONCLUSION

Our results indicate that GBM cells are being transcriptionally reprogrammed in response to treatment; the mechanism of which may represent a therapeutic opportunity.

Incidence of childhood CNS tumours in Britain and variation in rates by definition of malignant behaviour: population-based study

Background

Intracranial and intraspinal tumours are the most numerous solid tumours in children. Some recently defined subtypes are relatively frequent in childhood. Many cancer registries routinely ascertain CNS tumours of all behaviours, while others only cover malignant neoplasms. Some behaviour codes have changed between revisions of the International Classification of Diseases for Oncology, including pilocytic astrocytoma, downgraded to uncertain behaviour in ICD-O-3.

Methods

We used data from the population-based National Registry of Childhood Tumours, which routinely included non-malignant CNS tumours, to document the occurrence of CNS tumours among children aged < 15 years in Great Britain during 2001–2010 and to document the descriptive epidemiology of childhood CNS tumours over the 40-year period 1971–2010, during which several new entities were accommodated in successive editions of the WHO Classification and revisions of ICD-O. Eligible cases were all those with a diagnosis included in Groups III (CNS tumours) and Xa (CNS germ-cell tumours) of the International Classification of Childhood Cancer, Third Edition. The population at risk was derived from annual mid-year estimates by sex and single year of age compiled by the Office for National Statistics and its predecessors. Incidence rates were calculated for age groups 0, 1–4, 5–9 and 10–14 years, and age-standardised rates were calculated using the weights of the world standard population.

Results

Age-standardised incidence in 2001–10 was 40.1 per million. Astrocytomas accounted for 41%, embryonal tumours for 17%, other gliomas for 10%, ependymomas for 7%, rarer subtypes for 20% and unspecified tumours for 5%. Incidence of tumours classified as malignant and non-malignant by ICD-O-3 increased by 30 and 137% respectively between 1971-75 and 2006–10.

Conclusions

Total incidence was similar to that in other large western countries. Deficits of some, predominantly low-grade, tumours or differences in their age distribution compared with the United States and Nordic countries are compatible with delayed diagnosis. Complete registration regardless of tumour behaviour is essential for assessing burden of disease and changes over time. This is particularly important for pilocytic astrocytoma, because of its recent downgrading to non-malignant and time trends in the proportion of astrocytomas with specified subtype.

Estimation of amyloid distribution by [18F]flutemetamol PET predicts the neuropathological phase of amyloid β-protein deposition

The deposition of the amyloid β-protein (Aβ) in senile plaques is one of the histopathological hallmarks of Alzheimer's disease (AD). Aβ-plaques arise first in neocortical areas and, then, expand into further brain regions in a process described by 5 phases. Since it is possible to identify amyloid pathology with radioactive-labeled tracers by positron emission tomography (PET) the question arises whether it is possible to distinguish the neuropathological Aβ-phases with amyloid PET imaging. To address this question we reassessed 97 cases of the end-of-life study cohort of the phase 3 [¹⁸F]flutemetamol trial (ClinicalTrials.gov identifiers NCT01165554, and NCT02090855) by combining the standardized uptake value ratios (SUVRs) with pons as reference region for cortical and caudate nucleus-related [¹⁸F]flutemetamol-retention. We tested them for their prediction of the neuropathological pattern found at autopsy. By defining threshold levels for cortical and caudate nucleus SUVRs we could distinguish different levels of [¹⁸F]flutemetamol uptake termed PET-Aβ phase estimates. When comparing these PET-Aβ phase estimates with the neuropathological Aβ-phases we found that PET-Aβ phase estimate 0 corresponded with Aβ-phases 0-2, 1 with Aβ-phase 3, 2 with Aβ-phase 4, and 3 with Aβ-phase 5. Classification using the PET-Aβ phase estimates predicted the correct Aβ-phase in 72.16% of the cases studied here. Bootstrap analysis was used to confirm the robustness of the estimates around this association. When allowing a range of ± 1 phase for a given Aβ-phase correct classification was given in 96.91% of the cases. In doing so, we provide a novel method to convert SUVR-levels into PET-Aβ phase estimates that can be easily translated into neuropathological phases of Aβ-deposition. This method allows direct conclusions about the pathological distribution of amyloid plaques (Aβ-phases) in vivo. Accordingly, this method may be ideally suited to detect early preclinical AD-patients, to follow them with disease progression, and to provide a more precise prognosis for them based on the knowledge about the underlying pathological phase of the disease.

How to analyse the spatiotemporal tumour samples needed to investigate cancer evolution: A case study using paired primary and recurrent glioblastoma

Many traits of cancer progression (e.g., development of metastases or resistance to therapy) are facilitated by tumour evolution: Darwinian selection of subclones with distinct genotypes or phenotypes that enable such progression. Characterising these subclones provide an opportunity to develop drugs to better target their specific properties but requires the accurate identification of somatic mutations shared across multiple spatiotemporal tumours from the same patient. Current best practices for calling somatic mutations are optimised for single samples, and risk being too conservative to identify shared mutations with low prevalence in some samples. We reasoned that datasets from multiple matched tumours can be used for mutual validation and thus propose an adapted two-stage approach: (1) low-stringency mutation calling to identify mutations shared across samples irrespective of the weight of evidence in a single sample; (2) high-stringency mutation calling to further characterise mutations present in a single sample. We applied our approach to three-independent cohorts of paired primary and recurrent glioblastoma tumours, two of which have previously been analysed using existing approaches, and found that it significantly increased the amount of biologically relevant shared somatic mutations identified. We also found that duplicate removal was detrimental when identifying shared somatic mutations. Our approach is also applicable when multiple datasets e.g. DNA and RNA are available for the same tumour.

Abstract P1-08-10: Introduction of H1047R oncogenic mutation of PI3K p110alpha subunit in HER2-overexpressing mammary epithelial cells confers a "stem-like" phenotype and acute sensitivity to HSP90 inhibition

The Human Epidermal Growth Factor Receptor 2 (HER2) oncogene is amplified in one-fifth of breast cancers (BC). However, development of resistance against standard anti-HER2 therapies poses a major clinical challenge. Anti-tumor efficacy of HER2-targeting agents depends on inhibition of the downstream phosphatidylinositol-3 kinase (PI3K) signaling cascade. Gain-of-function somatic mutations in the gene encoding the PI3K catalytic subunit p110alpha (PIK3CA), co-expressed in about 40% of HER2+ BC, have been implicated in conferring resistance to HER2 monoclonal antibody herceptin. The single amino acid alteration H1047R within the kinase domain of PIK3CA is one of three hot spot mutations prevalent in BC.

Previously, we demonstrated that introduction of H1047R mutation in HER2-overexpressing MCF10A mammary epithelial cells enhances cellular transformation and decreases herceptin sensitivity by inducing secretion of endogenous ErbB ligand heregulin. However, genetic ablation of HER3, the major co-receptor for HER2 and the solitary receptor for heregulin, was insufficient for complete inhibition of cell growth, indicating the existence of additional mechanism/s responsible for the heightened aggressiveness and decreased drug sensitivity of HER2/H1047RPI3K cells. In the current study, we looked further into the molecular changes within these cells that might be responsible for these phenomena.

When compared with the HER2/WTPI3K cells, the HER2/H1047RPI3K cells revealed a significant increase in CD44high/CD24low/negative populations, common markers of BC stem cells, as well as molecular and phenotypic changes associated with epithelial-to-mesenchymal transition. These observations are in agreement with previously published report on mouse model of HER2/H1047RPI3K BC. Further analyses demonstrated additional stem cell-associated characteristics in HER2/H1047RPI3K cells, such as expression of angiogenic and inflammatory cytokines, ability to induce chemotaxis and invasion, activation of TGFb and NFKb signaling pathways. Connectivity map (CMap) analysis of the gene expression signatures from HER2/H1047RPI3K cells revealed a negative association with those from BC cells treated with 17AAG, an inhibitor of the heat shock protein 90 (HSP90). In line with this, HER2/H1047RPI3K-expressing cells are found to be more sensitive to HSP90 inhibition compared to the pan-ErbB inhibitor lapatinib.

Cancer stem cells are implicated in drug resistance and tumor recurrence. Enrichment of cell population expressing high levels of stem cell markers and stem cell-related features could be one of major mechanisms by which BC cells co-expressing HER2 and H1047RPI3K adapt to anti-HER2 therapeutic agents. Acute dependence on molecular chaperone HSP90 provides a unique, yet practical opportunity to effectively inhibit tumors harboring both molecular alterations, since HSP90 inhibitors have already shown encouraging clinical activity in herceptin-resistant setting.

Citation Format: Surendran S, Bhola N, Arteaga CL, Chakraborty K, Chakrabarty A. Introduction of H1047R oncogenic mutation of PI3K p110alpha subunit in HER2-overexpressing mammary epithelial cells confers a "stem-like" phenotype and acute sensitivity to HSP90 inhibition [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-08-10.

Post-mortem histopathology underlying β-amyloid PET imaging following flutemetamol F 18 injection

In vivo imaging of fibrillar β-amyloid deposits may assist clinical diagnosis of Alzheimer's disease (AD), aid treatment selection for patients, assist clinical trials of therapeutic drugs through subject selection, and be used as an outcome measure. A recent phase III trial of [¹⁸F]flutemetamol positron emission tomography (PET) imaging in 106 end-of-life subjects demonstrated the ability to identify fibrillar β-amyloid by comparing in vivo PET to post-mortem histopathology. Post-mortem analyses demonstrated a broad and continuous spectrum of β-amyloid pathology in AD and other dementing and non-dementing disease groups. The GE067-026 trial demonstrated 91% sensitivity and 90% specificity of [¹⁸F]flutemetamol PET by majority read for the presence of moderate or frequent plaques. The probability of an abnormal [¹⁸F]flutemetamol scan increased with neocortical plaque density and AD diagnosis. All dementia cases with non-AD neurodegenerative diseases and those without histopathological features of β-amyloid deposits were [¹⁸F]flutemetamol negative. Majority PET assessments accurately reflected the amyloid plaque burden in 90% of cases. However, ten cases demonstrated a mismatch between PET image interpretations and post-mortem findings. Although tracer retention was best associated with amyloid in neuritic plaques, amyloid in diffuse plaques and cerebral amyloid angiopathy best explain three [¹⁸F]flutemetamol positive cases with mismatched (sparse) neuritic plaque burden. Advanced cortical atrophy was associated with the seven false negative [¹⁸F]flutemetamol images. The interpretation of images from pathologically equivocal cases was associated with low reader confidence and inter-reader agreement. Our results support that amyloid in neuritic plaque burden is the primary form of β-amyloid pathology detectable with [¹⁸F]flutemetamol PET imaging. ClinicalTrials.gov NCT01165554. Registered June 21, 2010; NCT02090855. Registered March 11, 2014.

Description and Validation of Histological Patterns and Proposal of a Dynamic Model of Inflammatory Infiltration in Giant-cell Arteritis

The extent of inflammatory infiltrates in arteries from patients with giant-cell arteritis (GCA) have been described using different terms and definitions. Studies investigating the relationship between GCA histological features and clinical manifestations have produced controversial results. The aims of this study were to characterize and validate histological patterns in temporal artery biopsies (TABs) from GCA patients, to explore additional histological features, including the coexistence of different patterns, and also to investigate the relationship of the inflammatory patterns with clinical and laboratory features.We performed histological examination of TAB from patients with GCA consecutively diagnosed between 1992 and 2012. Patterns of inflammation were defined according to the extent and distribution of inflammatory infiltrates within the artery. Clinical and laboratory variables were recorded. Two external investigators underwent a focused, one-day training session and then independently scored 77 cases. Quadratic-weighted kappa was calculated.TAB from 285 patients (200 female/85 male) were evaluated. Four histological inflammatory patterns were distinguished: 1 - adventitial (n = 16); 2 - adventitial invasive: adventitial involvement with some extension to the muscular layer (n = 21); 3 - concentric bilayer: adventitial and intimal involvement with media layer preservation (n = 52); and 4 - panarteritic (n = 196). Skip lesions were observed in 10% and coexistence of various patterns in 43%. Raw agreement of each external scorer with the gold-standard was 82% and 77% (55% and 46% agreement expected from chance); kappa = 0.82 (95% confidence interval [CI] 0.70-0.95) and 0.79 (95% CI 0.68-0.91). Although abnormalities on temporal artery palpation and the presence of jaw claudication and scalp tenderness tended to occur more frequently in patients with arteries depicting more extensive inflammation, no statistically significant correlations were found between histological patterns and clinical features or laboratory findings.In conclusion, we have described and validated 4 histological patterns. The presence of different coexisting patterns likely reflects sequential steps in the progression of inflammation and injury. No clear relationship was found between these patterns and clinical or laboratory findings. However, several cranial manifestations tended to occur more often in patients with temporal arteries exhibiting panarteritic inflammation. This validated score system may be useful to standardize stratification of histological severity for immunopathology biomarker studies or correlation with imaging.

[(18)F]flutemetamol amyloid positron emission tomography in preclinical and symptomatic Alzheimer's disease: specific detection of advanced phases of amyloid-β pathology

BACKGROUND

Amyloid positron emission tomography (PET) has become an important tool to identify amyloid-β (Aβ) pathology in Alzheimer's disease (AD) patients. Here, we determined the diagnostic value of the amyloid PET tracer [(18)F]flutemetamol in relation to Aβ pathology at autopsy.

METHODS

[(18)F]flutemetamol PET was carried out in a cohort of 68 patients included in a [(18)F]flutemetamol amyloid PET imaging end-of-life study (GE067-007). At autopsy, AD pathology was determined and Aβ plaque pathology was classified into phases of its regional distribution (0-5).

RESULTS

[(18)F]flutemetamol PET was universally positive in cases with advanced stage postmortem Aβ pathology (Aβ phases 4 and 5). Negative amyloid PET was universally observed in nondemented or non-AD dementia cases with initial Aβ phases 1 and 2, whereas 33.3% of the phase 3 cases were positive.

CONCLUSIONS

[(18)F]flutemetamol amyloid PET detects primarily advanced stages of Aβ pathology in preclinical and symptomatic AD cases.

Atypical teratoid rhabdoid tumour of the spine: report of a case and literature review

Atypical teratoid rhabdoid tumour (ATRT) is a rare and highly aggressive malignant neoplasm of the central nervous system (CNS), which occurs predominantly in children less than 2 years of age. There are less than 50 cases described in adult. We report a case of primary spinal ATRT in a 65-year-old male who presented to us with cauda equina syndrome. To the best of our knowledge, our patient is the (1) second oldest patient to be diagnosed with ATRT and only the third case of adult spinal ATRT report in the literature; (2) first reported case of CNS ATRT occurring in a patient with non-rhabdoid renal cancer; (3) first adult patient of ATRT to present with cauda equina syndrome.

Methylation-specific multiplex ligation-dependent probe amplification identifies promoter methylation events associated with survival in glioblastoma

DNA methylation plays an important role in cancer biology and methylation events are important prognostic and predictive markers in many tumor types. We have used methylation-specific multiplex ligation-dependent probe amplification to survey the methylation status of MGMT and 25 tumor suppressor genes in 73 glioblastoma cases. The data obtained was correlated with overall survival and response to treatment. The study revealed that methylation of promoter regions in TP73 (seven patients), THBS1 (eight patients) and PYCARD (nine patients) was associated with improved outcome, whereas GATA5 (21 patients) and WT1 (24 patients) promoter methylation were associated with poor outcome. In patients treated with temozolomide and radiation MGMT and PYCARD promoter methylation events remained associated with improved survival whereas GATA5 was associated with a poor outcome. The identification of GATA5 promoter methylation in glioblastoma has not previously been reported. Furthermore, a cumulative methylation score separated patients into survival groups better than any single methylation event. In conclusion, we have identified specific methylation events associated with patient outcome and treatment response in glioblastoma, and these may be of functional and predictive/prognostic significance. This study therefore provides novel candidates and approaches for future prospective validation.

Early-onset Lafora body disease

The most common progressive myoclonus epilepsies are the late infantile and late infantile-variant neuronal ceroid lipofuscinoses (onset before the age of 6 years), Unverricht-Lundborg disease (onset after the age of 6 years) and Lafora disease. Lafora disease is a distinct disorder with uniform course: onset in teenage years, followed by progressively worsening myoclonus, seizures, visual hallucinations and cognitive decline, leading to a vegetative state in status myoclonicus and death within 10 years. Biopsy reveals Lafora bodies, which are pathognomonic and not seen with any other progressive myoclonus epilepsies. Lafora bodies are aggregates of polyglucosans, poorly constructed glycogen molecules with inordinately long strands that render them insoluble. Lafora disease is caused by mutations in the EPM2A or EPM2B genes, encoding the laforin phosphatase and the malin ubiquitin ligase, respectively, two cytoplasmically active enzymes that regulate glycogen construction, ensuring symmetric expansion into a spherical shape, essential to its solubility. In this work, we report a new progressive myoclonus epilepsy associated with Lafora bodies, early-onset Lafora body disease, map its locus to chromosome 4q21.21, identify its gene and mutation and characterize the relationship of its gene product with laforin and malin. Early-onset Lafora body disease presents early, at 5 years, with dysarthria, myoclonus and ataxia. The combination of early-onset and early dysarthria strongly suggests late infantile-variant neuronal ceroid lipofuscinosis, not Lafora disease. Pathology reveals no ceroid lipofuscinosis, but Lafora bodies. The subsequent course is a typical progressive myoclonus epilepsy, though much more protracted than any infantile neuronal ceroid lipofuscinosis, or Lafora disease, patients living into the fourth decade. The mutation, c.781T>C (Phe261Leu), is in a gene of unknown function, PRDM8. We show that the PRDM8 protein interacts with laforin and malin and causes translocation of the two proteins to the nucleus. We find that Phe261Leu-PRDM8 results in excessive sequestration of laforin and malin in the nucleus and that it therefore likely represents a gain-of-function mutation that leads to an effective deficiency of cytoplasmic laforin and malin. We have identified a new progressive myoclonus epilepsy with Lafora bodies, early-onset Lafora body disease, 101 years after Lafora disease was first described. The results to date suggest that PRDM8, the early-onset Lafora body disease protein, regulates the cytoplasmic quantities of the Lafora disease enzymes.