Exploring whether primary care networks can contribute to the national goal of reducing health inequalities: a mixed-methods study

BACKGROUND

Significant health inequalities exist in England. Primary care networks (PCNs), comprised of GP practices, were introduced in England in 2019 with funding linked to membership. PCNs have been tasked with tackling health inequalities.

AIM

To consider how the design and introduction of PCNs might influence their ability to tackle health inequalities.

DESIGN AND SETTING

A sequential mixed-methods study of PCNs in England.

METHOD

Linear regression of annual PCN-allocated funding per workload-weighted patient on income deprivation score from 2019-2023 was used. Qualitative interviews and observations of PCNs and PCN staff were undertaken across seven PCN sites in England (July 2020-March 2022).

RESULTS

Across 1243 networks in 2019-2020, a 10% higher level of income deprivation resulted in £0.31 (95% confidence interval [CI] = £0.25 to £0.37), 4.50%, less funding per weighted patient. In 2022-2023, the same difference in deprivation resulted in £0.16 (95% CI = £0.11 to £0.21), 0.60%, more funding. Qualitative interviews highlighted that, although there were requirements for PCNs to tackle health inequalities, the policy design, and PCN internal relationships and maturity, shaped and sometimes restricted how PCNs approached this task locally.

CONCLUSION

Allocated PCN funding has become more pro-poor over time, suggesting that the need to account for deprivation within funding models is understood by policymakers. The following additional approaches have been highlighted that could support PCNs to tackle inequalities: better management support; encouragement and support to redistribute funding internally to support practices serving more deprived populations; and greater specificity in service requirements.

Implementing the Additional Roles Reimbursement Scheme in seven English Primary Care Networks: a qualitative study

BACKGROUND

The Additional Roles Reimbursement Scheme (ARRS) provides funding to Primary Care Networks (PCNs) in England to recruit additional staff into specified roles. The intention was to support general practice by recruiting an extra 26 000 staff by 2024, increasing access and easing workload pressures.

AIM

To explore the establishment of the ARRS as part of PCNs' development to understand their role in supporting general practice.

DESIGN AND SETTING

A longitudinal, qualitative case study involving seven geographically dispersed PCNs across England.

METHOD

Data were collected from July 2020 to March 2022, including 91 semi-structured interviews and 87 h of meeting observations. Transcripts were analysed using the framework approach.

RESULTS

Implementation of the ARRS was variable across the study sites, but most shared similar experiences and concerns. The COVID-19 pandemic had a significant impact on the introduction of the new roles, and significant variability was found in modes of employment. Cross-cutting issues included: the need for additional space to accommodate new staff; the inflexibility of aspects of the scheme, including reinvestment of unspent funds; and the need for support and oversight of employed staff. Perceived benefits of the ARRS include improved patient care and the potential to save GP time.

CONCLUSION

The findings suggest the ARRS has potential to fulfil its objective of supporting and improving access to general practice. However, attention to operational requirements including appropriate funding, estates, and management of staff is important if this is to be realised, as is clarity for the scheme post-contract end in 2024.

Definition and Assessment of Paediatric Breakthrough Pain: A Qualitative Interview Study

Infants, children and young people with life-limiting or life-threatening conditions often experience acute, transient pain episodes known as breakthrough pain. There is currently no established way to assess breakthrough pain in paediatric palliative care. Anecdotal evidence suggests that it is frequently underdiagnosed and undertreated, resulting in reduced quality of life. The development of a standardised paediatric breakthrough pain assessment, based on healthcare professionals' insights, could improve patient outcomes. This study aimed to explore how healthcare professionals define and assess breakthrough pain in paediatric palliative care and their attitudes towards a validated paediatric breakthrough pain assessment. This was a descriptive qualitative interview study. Semi-structured interviews were conducted with 29 healthcare professionals working in paediatric palliative care across the UK. An inductive thematic analysis was conducted on the data. Five themes were generated: 'the elusive nature of breakthrough pain', 'breakthrough pain assessment', 'positive attitudes towards', 'reservations towards' and 'features to include in' a paediatric breakthrough pain assessment. The definition and assessment of breakthrough pain is inconsistent in paediatric palliative care. There is a clear need for a validated assessment questionnaire to improve assessment, diagnosis and management of breakthrough pain followed by increased healthcare professional education on the concept.

Brain stem tumors in children less than 3 months: Clinical and radiologic findings of a rare disease

PURPOSE

Brain stem tumors in children < 3 months at diagnosis are extremely rare. Our aim is to study a retrospective cohort to improve the understanding of the disease course and guide patient management.

METHODS

This is a multicenter retrospective analysis across the European Society for Pediatric Oncology SIOP-E HGG/DIPG Working Group linked centers, including patients with a brainstem tumor diagnosed between 2009 and 2020 and aged < 3 months at diagnosis. Clinical data were collected, and imaging characteristics were analyzed blindly and independently by two neuroradiologists.

RESULTS

Five cases were identified. No patient received any therapy. The epicenter of two tumors was in the medulla oblongata alone and in the medulla oblongata and the pons in three. For patients with tumor in equal parts in the medulla oblongata and the pons (n = 3), the extension at diagnosis involved the spinal cord; for the two patients with the tumor epicenter in the medulla oblongata alone (n = 2), the extension at diagnosis included the pons (n = 2) and the spinal cord (n = 1). Biopsy was performed in one patient identifying a pilocytic astrocytoma. Two patients died. In one patient, autopsy revealed a high-grade glioma (case 3). Three survivors showed either spontaneous tumor regression (n = 2) or stable disease (n = 1). Survivors were followed up for 10, 7, and 0.6 years, respectively. One case had the typical imaging characteristics of a dorsal exophytic low-grade glioma.

CONCLUSIONS

No patient fulfilled the radiologic criteria defining a high-grade glioma. Central neuroradiological review and biopsy may provide useful information regarding the patient management.

Noise suppression of proton magnetic resonance spectroscopy improves paediatric brain tumour classification

Proton magnetic resonance spectroscopy (1 H-MRS) is increasingly used for clinical brain tumour diagnosis, but suffers from limited spectral quality. This retrospective and comparative study aims at improving paediatric brain tumour classification by performing noise suppression on clinical 1 H-MRS. Eighty-three/forty-two children with either an ependymoma (ages 4.6± $$ \pm $$ 5.3/9.3± $$ \pm $$ 5.4), a medulloblastoma (ages 6.9± $$ \pm $$ 3.5/6.5± $$ \pm $$ 4.4), or a pilocytic astrocytoma (8.0± $$ \pm $$ 3.6/6.3± $$ \pm $$ 5.0), recruited from four centres across England, were scanned with 1.5T/3T short-echo-time point-resolved spectroscopy. The acquired raw 1 H-MRS was quantified by using Totally Automatic Robust Quantitation in NMR (TARQUIN), assessed by experienced spectroscopists, and processed with adaptive wavelet noise suppression (AWNS). Metabolite concentrations were extracted as features, selected based on multiclass receiver operating characteristics, and finally used for identifying brain tumour types with supervised machine learning. The minority class was oversampled through the synthetic minority oversampling technique for comparison purposes. Post-noise-suppression 1 H-MRS showed significantly elevated signal-to-noise ratios (P < .05, Wilcoxon signed-rank test), stable full width at half-maximum (P > .05, Wilcoxon signed-rank test), and significantly higher classification accuracy (P < .05, Wilcoxon signed-rank test). Specifically, the cross-validated overall and balanced classification accuracies can be improved from 81% to 88% overall and 76% to 86% balanced for the 1.5T cohort, whilst for the 3T cohort they can be improved from 62% to 76% overall and 46% to 56%, by applying Naïve Bayes on the oversampled 1 H-MRS. The study shows that fitting-based signal-to-noise ratios of clinical 1 H-MRS can be significantly improved by using AWNS with insignificantly altered line width, and the post-noise-suppression 1 H-MRS may have better diagnostic performance for paediatric brain tumours.

Correction: Bailey et al. Clinical Trials in High-Risk Medulloblastoma: Evolution of the SIOP-Europe HR-MB Trial. Cancers 2022, 14, 374

In the original publication [...].

The clinical significance of sub-total surgical resection in childhood medulloblastoma: a multi-cohort analysis of 1100 patients

Background

Medulloblastoma patients with a sub-total surgical resection (STR; >1.5 cm2 primary tumour residuum post-surgery) typically receive intensified treatment. However, the association of STR with poor outcomes has not been observed consistently, questioning the validity of STR as a high-risk disease feature.

Methods

We collected extent of resection (EOR) data from 1110 patients (from UK CCLG centres (n = 416, collected between September 1990 and July 2014) and published (n = 694) cohorts), the largest cohort of molecularly and clinically annotated tumours assembled to specifically assess the significance of EOR. We performed association and univariable/multivariable survival analyses, assessing overall survival (OS) cohort-wide and with reference to the four consensus medulloblastoma molecular groups and clinical features.

Findings

STR was reported in 20% (226/1110) of patients. Non-WNT (p = 0.047), children <5 years at diagnosis (p = 0.021) and metastatic patients (p < 0.0001) were significantly more likely to have a STR. In cohort-wide analysis, STR was associated with worse survival in univariable analysis (p < 0.0001). Examination of specific disease contexts showed that STR was prognostic in univariate analysis for patients receiving cranio-spinal irradiation (CSI) and chemotherapy (p = 0.016) and for patients with Group 3 tumours receiving CSI (p = 0.039). STR was not independently prognostic in multivariable analyses; outcomes for patients who have STR as their only risk-feature are as per standard-risk disease. Specifically, STR was not prognostic in non-metastatic patients that received upfront CSI.

Interpretation

In a cohort of 1100 molecularly characterised medulloblastoma patients, STR (n = 226) predicted significantly lower OS in univariable analysis, but was not an independent prognostic factor. Our data suggest that maximal safe resection can continue to be carried out for patients with medulloblastoma and suggest STR should not inform patient management when observed as a sole, isolated risk-feature.

Funding

Cancer Research UK, Newcastle Hospitals Charity, Children's Cancer North, British Division of the International Academy of Pathology.

A paradox of problems in accessing general practice: a qualitative participatory case study

BACKGROUND

Despite longstanding problems of access to general practice, attempts to understand and address the issues do not adequately include perspectives of the people providing or using care, nor do they use established theories of access to understand complexity.

AIM

To understand problems of access to general practice from the multiple perspectives of service users and staff using an applied theory of access.

DESIGN AND SETTING

A qualitative participatory case study in an area of northwest England.

METHOD

A community-based participatory approach was used with qualitative interviews, focus groups, and observation to understand perspectives about accessing general practice. Data were collected between October 2015 and October 2016. Inductive and abductive analysis, informed by Levesque et al's theory of access, allowed the team to identify complexities and relationships between interrelated problems.

RESULTS

This study presents a paradox of problems in accessing general practice, in which the demand on general practice both creates and hides unmet need in the population. Data show how reactive rules to control demand have undermined important aspects of care, such as continuity. The layers of rules and decreased continuity create extra work for practice staff, clinicians, and patients. Complicated rules, combined with a lack of capacity to reach out or be flexible, leave many patients, including those with complex and/or unrecognised health needs, unable to navigate the system to access care. This relationship between demand and unmet need exacerbates existing health inequities.

CONCLUSION

Understanding the paradox of access problems allows for different targets for change and different solutions to free up capacity in general practice to address the unmet need in the population.

Metabolite profiles of medulloblastoma for rapid and non-invasive detection of molecular disease groups

BACKGROUND

The malignant childhood brain tumour, medulloblastoma, is classified clinically into molecular groups which guide therapy. DNA-methylation profiling is the current classification 'gold-standard', typically delivered 3-4 weeks post-surgery. Pre-surgery non-invasive diagnostics thus offer significant potential to improve early diagnosis and clinical management. Here, we determine tumour metabolite profiles of the four medulloblastoma groups, assess their diagnostic utility using tumour tissue and potential for non-invasive diagnosis using in vivo magnetic resonance spectroscopy (MRS).

METHODS

Metabolite profiles were acquired by high-resolution magic-angle spinning NMR spectroscopy (MAS) from 86 medulloblastomas (from 59 male and 27 female patients), previously classified by DNA-methylation array (WNT (n = 9), SHH (n = 22), Group3 (n = 21), Group4 (n = 34)); RNA-seq data was available for sixty. Unsupervised class-discovery was performed and a support vector machine (SVM) constructed to assess diagnostic performance. The SVM classifier was adapted to use only metabolites (n = 10) routinely quantified from in vivo MRS data, and re-tested. Glutamate was assessed as a predictor of overall survival.

FINDINGS

Group-specific metabolite profiles were identified; tumours clustered with good concordance to their reference molecular group (93%). GABA was only detected in WNT, taurine was low in SHH and lipids were high in Group3. The tissue-based metabolite SVM classifier had a cross-validated accuracy of 89% (100% for WNT) and, adapted to use metabolites routinely quantified in vivo, gave a combined classification accuracy of 90% for SHH, Group3 and Group4. Glutamate predicted survival after incorporating known risk-factors (HR = 3.39, 95% CI 1.4-8.1, p = 0.025).

INTERPRETATION

Tissue metabolite profiles characterise medulloblastoma molecular groups. Their combination with machine learning can aid rapid diagnosis from tissue and potentially in vivo. Specific metabolites provide important information; GABA identifying WNT and glutamate conferring poor prognosis.

FUNDING

Children with Cancer UK, Cancer Research UK, Children's Cancer North and a Newcastle University PhD studentship.

Methylphenidate improves cognitive function and health-related quality of life in survivors of childhood brain tumours

OBJECTIVES

The growing population of survivors of childhood brain tumors present the challenge of long-term quality of survival. The domains most affected by tumor and treatment are those implicated in development of typical intellectual functions: attention, working memory, and processing speed, with consequent effects upon function and quality of life. In this paper we present service evaluation data on the 12-month effect upon processing speed, visual and auditory attentional domains in 29 patients receiving methylphenidate aged 5-16 years (Mean=10.6).

METHODS

Patients received immediate-release methylphenidate and were converted to modified-release as appropriate. Mean optimal dose of immediate-release methylphenidate was 0.34 mg/kg per dose (range 0.2-0.67).

RESULTS

Patients showed a significant positive impact of methylphenidate on attention in all tests of selective visual attention from the Test of Everyday Attention for Children 2. A significant improvement was also shown on response time. Significant change was not found on psychometric measures of sustained auditory or visual attention, or selective auditory attention. Ratings of Health-Related Quality of Life showed a positive benefit of methylphenidate at 12 months. Side effects were minimal and not statistically significant.

CONCLUSIONS

Survivors of childhood brain tumor with attentional and processing speed deficit show clinical benefit from methylphenidate.

The type II RAF inhibitor tovorafenib in relapsed/refractory pediatric low-grade glioma: the phase 2 FIREFLY-1 trial

BRAF genomic alterations are the most common oncogenic drivers in pediatric low-grade glioma (pLGG). Arm 1 (n = 77) of the ongoing phase 2 FIREFLY-1 (PNOC026) trial investigated the efficacy of the oral, selective, central nervous system-penetrant, type II RAF inhibitor tovorafenib (420 mg m-2 once weekly; 600 mg maximum) in patients with BRAF-altered, relapsed/refractory pLGG. Arm 2 (n = 60) is an extension cohort, which provided treatment access for patients with RAF-altered pLGG after arm 1 closure. Based on independent review, according to Response Assessment in Neuro-Oncology High-Grade Glioma (RANO-HGG) criteria, the overall response rate (ORR) of 67% met the arm 1 prespecified primary endpoint; median duration of response (DOR) was 16.6 months; and median time to response (TTR) was 3.0 months (secondary endpoints). Other select arm 1 secondary endpoints included ORR, DOR and TTR as assessed by Response Assessment in Pediatric Neuro-Oncology Low-Grade Glioma (RAPNO) criteria and safety (assessed in all treated patients and the primary endpoint for arm 2, n = 137). The ORR according to RAPNO criteria (including minor responses) was 51%; median DOR was 13.8 months; and median TTR was 5.3 months. The most common treatment-related adverse events (TRAEs) were hair color changes (76%), elevated creatine phosphokinase (56%) and anemia (49%). Grade ≥3 TRAEs occurred in 42% of patients. Nine (7%) patients had TRAEs leading to discontinuation of tovorafenib. These data indicate that tovorafenib could be an effective therapy for BRAF-altered, relapsed/refractory pLGG. ClinicalTrials.gov registration: NCT04775485 .

Successfully targeting the cancer system with metronomics for medulloblastoma

The prognosis of the patients with medulloblastoma who relapse after initial treatment including radiotherapy remains dismal. A recent study by Peyrl et al. in JAMA Oncology suggests that the metronomic multidrug combination used in the medulloblastoma European multitarget metronomic antiangiogenic trial (MEMMAT) given at relapse can improve long-term survival.

COVID-19 Pandemic Associations on Mental and Physical Health in African Americans Participating in a Behavioral Intervention

The COVID-19 pandemic has had disproportionate effects on communities of color, with higher death rates among African Americans (AA). The purpose of this study was to assess associations in African Americans' mental and physical health with the COVID-19 pandemic. Data for this study came from a larger nutrition intervention of AAs in the Southeastern United States, the Nutritious Eating with Soul study. Data collected before and after March 15, 2020 (the day when local South Carolina schools and businesses closed), were analyzed to assess the association of the pandemic on participants' stress, control of healthy eating, physical activity, and body mass index. Repeated measures analysis of covariance using full maximum likelihood estimation to handle missing data was used. At the onset of the COVID-19 pandemic, 150 participants were enrolled in the study (48.2 ± 10.6 years old, 79% female, 75% with college degree or higher). Participants' reporting of stress did not show statistically significant change over time. Cognitive control increased 1.43 points (F = 20.60, p < 0.0001) and body mass index increased 0.72 kg/m2 (F = 10.68, p = 0.001). Future longitudinal studies should investigate how the COVID-19 pandemic continues to present challenges to understanding and improving health among African Americans. The study is registered at www.clinicaltrials.gov NCT03354377.

Primary care networks as a means of supporting primary care: findings from qualitative case study-based evaluation in the English NHS

OBJECTIVES

This study aimed to evaluate primary care networks (PCNs) in the English National Health Service. We ask: How are PCNs constituted to meet their defined goals? What factors can be discerned as affecting their ability to deliver benefits to the community, the network as a whole and individual members? What outcomes or outputs are associated with PCNs so far? We draw policy lessons for PCN design and oversight, and consider the utility of the chosen evaluative framework.

DESIGN AND SETTING

Qualitative case studies in seven PCN in England, chosen for maximum variety around geography, rurality and population deprivation. Study took place between May 2019 and December 2022.

PARTICIPANTS

PCN members, staff employed in additional roles and local managers. Ninety-one semistructured interviews and approximately 87 hours of observations were undertaken remotely. Interview transcripts and observational field notes were analysed together using a framework approach. Initial codes were derived from our evaluation framework, with inductive coding of new concepts during the analysis.

RESULTS

PCNs have been successfully established across England, with considerable variation in structure and operation. Progress is variable, with a number of factors affecting this. Good managerial support was helpful for PCN development. The requirement to work together to meet the specific threat of the global pandemic did, in many cases, generate a virtuous cycle by which the experience of working together built trust and legitimacy. The internal dynamics of networks require attention. Pre-existing strong relationships provided a significant advantage. While policy cannot legislate to create such relationships, awareness of their presence/absence is important.

CONCLUSIONS

Networked approaches to service delivery are popular in many health systems. Our use of an explicit evaluation framework supports the extrapolation of our findings to networks elsewhere. We found the framework to be useful in structuring our study but suggest some modifications for future use.

Identifying possible thresholds for nonstructural carbohydrates in the insulin dysregulated horse

BACKGROUND

Identifying intake levels of nonstructural carbohydrates (NSCs) that limit the postprandial insulinaemic response in the insulin dysregulated (ID) horse may help reduce hyperinsulinaemia-associated laminitis (HAL) risk.

OBJECTIVE

To determine if ID horses have thresholds for pure sources of starch and sugar, above which there is an augmented insulin response.

STUDY DESIGN

Randomised crossover experiment.

METHODS

Fourteen adult horses (6 ID and 8 noninsulin dysregulated, NID; matched for bodyweight) were randomly fed eight dietary treatments. Dietary treatments were formulated using a base of low-nonstructural carbohydrate pellet (LNSC; 0.04 g of water-soluble carbohydrates (WSCs)/kg bwt and 0.01 g of starch/kg bwt), to which pure sugar (dextrose) or starch (50:50 mix of waxy-maize and oat starch powder) sources were titrated to create diets with increasing amounts of either WSC (0.06-0.17 g WSC/kg bwt), or starch (0.03-0.1 g starch/kg bwt). Horses were fed each dietary treatment at a rate of 1 g/kg bwt once over 12 weeks. Serial blood samples were collected pre- and up to 240 min postprandially. Insulin was determined via RIA and diet analytes were determined via wet chemistry. Statistical analysis was performed with a mixed effect model. Positive incremental area under the curve for insulin (IAUCi) was calculated for all horses and dietary treatments.

RESULTS

There was no significant effect of diet in NID horses but diets with NSC >0.1 g/kg bwt produced an augmented response in ID horses compared with the LNSC (p < 0.05). ID horses IAUCi were also significantly different to all NID IAUCi for diets with NSC >0.1 g/kg (p < 0.04). Apparent thresholds for sugar and starch addition varied.

CONCLUSIONS

Based on this study, using supplemental pure starch and sugar sources, ID horses seem to have an apparent threshold for NSC of around 0.1 g/kg bwt/meal, above which significantly increased insulin responses are seen compared with NID horses.

SIOP PODC-adapted treatment guidelines for craniopharyngioma in low- and middle-income settings

Pediatric craniopharyngioma is a rare tumor with excellent survival but significant long-term morbidities due to the loco-regional tumor growth or secondary to its treatment. Visual impairment, panhypopituitarism, hypothalamic damage, and behavioral changes are among the main challenges. This tumor should be managed under the care of a multidisciplinary team to determine the optimum treatment within the available resources. This is particularly important for low middle-income countries where resources are variable. This report provides risk-stratified management guidelines for children diagnosed with craniopharyngioma in a resource-limited setting.

Trauma-informed prevention programmes for depression, anxiety, and substance use among young people: protocol for a mixed-methods systematic review

BACKGROUND

Mental ill-health and substance use bear a substantial burden and harm on young people and often arise from co-occurring and compounding risk factors, such as traumatic stress. Trauma-informed prevention of mental ill-health and substance use demonstrates significant promise in reducing this burden. A systematic literature review is required to identify and summarise the effectiveness, feasibility, acceptability, and design principles underpinning existing trauma-informed mental ill-health and/or substance use prevention programmes for young people aged 12-24 years.

METHODS

MEDLINE, Embase, CINAHL, PsychINFO, and Cochrane Library will be searched from 2012 through September 2022. Reference lists of included articles will be citation-chained. Title and abstracts will be screened and two reviewers will review articles full-text. One reviewer will extract data from eligible articles using a piloted data extraction form, and 20% of the data will be verified by a second reviewer. Risk of bias will be assessed using the Cochrane risk-of-bias tool for randomised trials (RoB 2), Risk of Bias in Non-randomised Studies of Interventions (ROBINS-I), and The Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Studies and The Joanna Briggs Institute Critical Appraisal Checklist for Qualitative Research (CASP), depending on the study type. Characteristics of existing trauma-informed mental ill-health and/or substance use prevention programmes for young people will be summarised narratively. Effectiveness, feasibility, and acceptability will be qualitatively described and summarised, with proportions and effect sizes quantitatively synthesised, where possible.

DISCUSSION

Trauma-informed approaches to prevention demonstrate significant promise, yet to date, no study has systematically summarised and synthesised the available literature. To fill this gap, the present review will systematically identify and summarise the effectiveness, feasibility, acceptability, and design principles underpinning existing trauma-informed mental health and/or substance use prevention programmes for young people aged 12-24. This review will inform the development, adaptation, evaluation, and implementation of future trauma-informed mental ill-health and substance use prevention programmes for young people. Findings will inform critical efforts to interrupt and prevent already elevated trajectories of mental ill-health, substance use, and related harms among those young people exposed to adversity.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022353883.

Quality and Safety Considerations in Image Guided Radiation Therapy: An ASTRO Safety White Paper Update

PURPOSE/OBJECTIVE(S)

This updated report on image guided radiation therapy (IGRT) is based on a consensus-based white paper previously published by the American Society for Radiation Oncology (ASTRO) addressing patient safety. In the past decade, IGRT technology and procedures have progressed significantly and are now more commonly used. The use of IGRT has now extended beyond high-precision treatments, such as stereotactic radiosurgery and stereotactic body radiation therapy, and into routine clinical practice for many treatment techniques and anatomic sites. Therefore, quality and treatment planning and delivery considerations for these techniques are paramount for patient safety.

MATERIALS/METHODS

In 2021, ASTRO convened an interdisciplinary task force to assess the original IGRT white paper and update content where appropriate. Recommendations were created using a consensus-building methodology, and task force members indicated their level of agreement based on a 5-point Likert scale from "strongly agree" to "strongly disagree." A prespecified threshold of ≥75% of raters who selected "strongly agree" or "agree" indicated consensus.

RESULTS

The IGRT white paper was published (Pract Radiat Oncol. 2022 Dec) and endorsed by the American Association of Physicists in Medicine (AAPM), American Association of Medical Dosimetrists, and American Society of Radiologic Technologists. Since the first IGRT paper was published by ASTRO in 2013, significant technological advancement has taken place. New and updated considerations in personnel requirements, staffing, education and training, equipment and technological requirements, quality management and assurance, IGRT program management, and safety considerations were reported. A 17-point consensus was reached and recommended in 5 areas surrounding program development, quality assurance, quality management, treatment delivery, and vendor engagement (Table 5, Summary of key recommendations).

CONCLUSION

This IGRT white paper builds on the previous version and uses other guidance documents to primarily focus on processes related to quality and safety. IGRT requires an interdisciplinary team-based approach, staffed by appropriately trained specialists, as well as significant personnel resources, specialized technology, and implementation time. A thorough feasibility analysis of resources is required and should be discussed with all personnel before undertaking new imaging techniques. A comprehensive quality-assurance program must be developed to ensure IGRT is performed safely and effectively. As IGRT technologies continue to improve or emerge, existing practice guidelines should be updated regularly according to the latest AAPM Task Group reports. Patient safety in the application of IGRT is everyone's responsibility, and professional organizations, regulators, vendors, and end-users must demonstrate strong commitments to ensure that the highest levels of safety are achieved.

Barriers to the use of Methylphenidate in Pediatric Neuro-oncology Services

BACKGROUND

Survivors of childhood CNS tumors are at a significant risk of chronic and multifaceted neurocognitive late effects. Recent findings indicate the potential utility of methylphenidate in addressing neurocognitive and academic plateauing and improving quality-of-life outcomes in this clinical population. However, the prescription of methylphenidate in neuro-oncology services remains inconsistent.

OBJECTIVE

To explore the neurocognitive assessment and rehabilitative interventions (including the use of methylphenidate) offered to survivors of childhood CNS tumors within mainland UK.

METHOD

We used a semi-structured questionnaire to gather qualitative data from clinical psychologists and neuropsychologists within National Health Service pediatric neuro-oncology principal treatment centers (PTCs) during May 2018. Thematic analytical methods were used to explore themes within the collected data.

RESULTS

Eleven (58%) of the 19 PTCs returned the completed questionnaire. Respondents reported inadequate resource of psychology in many pediatric neuro-oncology PTCs, which limited the provision of methylphenidate to a restricted proportion of the patient group (i.e., those with the most profound neurocognitive difficulties). Respondents reported an interest in exploring the utility of methylphenidate in their patient group yet described a lack of appropriate evidence of its efficacy. In addition, respondents highlighted the need for the provision of accessible research summaries and treatment protocols addressing the use of methylphenidate.

CONCLUSION

We anticipate that national collaboration between clinicians and researchers working in the cancer survivorship field will support the advancement of interventions such as methylphenidate for the growing clinical population of survivors of childhood CNS tumors.

Timing is everything: A connection between medulloblastoma prognosis and foetal cerebellar development

The childhood brain tumour medulloblastoma is typically classified into multiple discrete molecular subgroups with characteristic DNA methylation and expression patterns. Several of these subgroups are used as, or proposed to be, an effective basis for treatment stratification. Here, we highlight the close connection between the findings described in a recent series of studies which, together, strongly imply a continuous association between survival outcome, the transcriptional profile of a Group3/Group4 (i.e. non-WNT/non-SHH) medulloblastoma and the specific point during early foetal cerebellar development at which initial pathogenic disruption took place. This has important implications for future efforts to model the disease by incorporating driving molecular features into their specific developmental context. This further suggests that instead of relying upon discrete DNA methylation subgroups, using expression biomarkers as the basis of a continuous risk predictor may produce a more effective risk stratification of patients with Group3/Group4 medulloblastoma.

How we can protect the protectors: learning from police officers and staff involved in child sexual abuse and exploitation investigations

Background

Police officers and staff who work in child sexual abuse and exploitation (CSAE) investigations are routinely exposed to traumatic materials and situations. Despite support services, working in this space can have negative impacts on wellbeing. This paper explores the experiences and perceptions held by police officers and staff involved in CSAE investigations in the United Kingdom, regarding work-related wellbeing support and barriers to accessing such support.

Method

A sample of 661 serving police officers and staff working in CSAE investigations participated in a United Kingdom-wide 'Protecting the Protectors' survey. We analysed quantitative and qualitative responses relating to participants' experiences and perceptions regarding three main areas: (1) availability, usage and helpfulness of existing work-based well-being support; (2) barriers to accessing support; and (3) desired support services.

Findings

Five interconnected themes emerged from the qualitative data that represented participants' experiences and views of work-based wellbeing support and the barriers to accessing it. These were 'Lack of trust', 'Stigma', 'Organisational approaches to wellbeing', 'Support services', and 'Internalised barriers'. The findings suggest that whilst respondents were aware of work-based support, they indicated most frequently that they 'never or almost never' used them. Respondents also identified barriers to accessing support, which related to a perception of a critical or judgmental workplace culture and indicating a lack of trust in their organisations.

Conclusion

Stigma regarding mental ill health has a pervasive and harmful impact on emotional health and wellbeing of police officers and staff involved in CSAE investigations, which creates a sense of lack of emotional safety. Therefore, eliminating stigma and creating a workplace culture that explicitly values and prioritises the emotional health and wellbeing of the workforce would improve the wellbeing of officers and staff. Police organisations could further improve CSAE teams' wellbeing by developing a continuum of care which is available to workers from recruitment to the end of the role, training managers and supervisors to better support CSAE teams, improving workplace practices, and ensuring high quality, specialist support services are readily and consistently available across forces.

Molecular characterisation defines clinically-actionable heterogeneity within Group 4 medulloblastoma and improves disease risk-stratification

Group 4 tumours (MBGrp4) represent the majority of non-WNT/non-SHH medulloblastomas. Their clinical course is poorly predicted by current risk-factors. MBGrp4 molecular substructures have been identified (e.g. subgroups/cytogenetics/mutations), however their inter-relationships and potential to improve clinical sub-classification and risk-stratification remain undefined. We comprehensively characterised the paediatric MBGrp4 molecular landscape and determined its utility to improve clinical management. A clinically-annotated discovery cohort (n = 362 MBGrp4) was assembled from UK-CCLG institutions and SIOP-UKCCSG-PNET3, HIT-SIOP-PNET4 and PNET HR + 5 clinical trials. Molecular profiling was undertaken, integrating driver mutations, second-generation non-WNT/non-SHH subgroups (1-8) and whole-chromosome aberrations (WCAs). Survival models were derived for patients ≥ 3 years of age who received contemporary multi-modal therapies (n = 323). We first independently derived and validated a favourable-risk WCA group (WCA-FR) characterised by ≥ 2 features from chromosome 7 gain, 8 loss, and 11 loss. Remaining patients were high-risk (WCA-HR). Subgroups 6 and 7 were enriched for WCA-FR (p < 0·0001) and aneuploidy. Subgroup 8 was defined by predominantly balanced genomes with isolated isochromosome 17q (p < 0·0001). While no mutations were associated with outcome and overall mutational burden was low, WCA-HR harboured recurrent chromatin remodelling mutations (p = 0·007). Integration of methylation and WCA groups improved risk-stratification models and outperformed established prognostication schemes. Our MBGrp4 risk-stratification scheme defines: favourable-risk (non-metastatic disease and (i) subgroup 7 or (ii) WCA-FR (21% of patients, 5-year PFS 97%)), very-high-risk (metastatic disease with WCA-HR (36%, 5-year PFS 49%)) and high-risk (remaining patients; 43%, 5-year PFS 67%). These findings validated in an independent MBGrp4 cohort (n = 668). Importantly, our findings demonstrate that previously established disease-wide risk-features (i.e. LCA histology and MYC(N) amplification) have little prognostic relevance in MBGrp4 disease. Novel validated survival models, integrating clinical features, methylation and WCA groups, improve outcome prediction and re-define risk-status for ~ 80% of MBGrp4. Our MBGrp4 favourable-risk group has MBWNT-like excellent outcomes, thereby doubling the proportion of medulloblastoma patients who could benefit from therapy de-escalation approaches, aimed at reducing treatment induced late-effects while sustaining survival outcomes. Novel approaches are urgently required for the very-high-risk patients.

Radiotherapy quality assurance in paediatric clinical trials: first report from six QUARTET-affiliated trials

BACKGROUND AND PURPOSE

SIOP Europe's QUARTET project launched in 2016; aiming to improve access to high-quality radiotherapy for children and adolescents treated within clinical trials across Europe. The aim of this report is to present the profile of institutions participating in six QUARTET-affiliated trials and a description of the initial individual case review (ICR) outcomes.

METHODS

This is a two-part analysis. Firstly, using facility questionnaires, beam output audit certificates, and advanced technique credentialing records to create a profile of approved institutions, and secondly, collating trial records for ICRs submitted prior to 31/10/2022. Trials included are: SIOPEN HR-NBL1, SIOPEN-LINES, SIOPEN- VERITAS, SIOP-BTG HRMB, EpSSG-FaR-RMS, and SIOPEN HR-NBL2.

RESULTS

By 31/10/2022, a total of 103 institutions had commenced QUARTET site approval procedures to participate in QUARTET-affiliated trials; 66 sites across 20 countries were approved. These participating institutions were often paediatric referral sites with intensity modulated radiotherapy or proton beam therapy, designated paediatric radiation oncologists, and paediatric adapted facilities and imaging protocols available. In total, 263 patient plans were submitted for ICR, 254 ICRs from 15 countries were completed. ICRs had a rejection rate of 39.8%, taking an average of 1.4 submissions until approval was achieved. Target delineation was the most frequent reason for rejection.

CONCLUSION

The QUARTET facility questionnaire is a valuable tool for mapping resources, personnel, and technology available to children and adolescents receiving radiotherapy. Prospective ICR is essential for paediatric oncology clinical trials and should be prioritised to reduce protocol violations.

Abstract 5719: Clinical response to the PDGFRα inhibitor avapritinib in high-grade glioma patients

PDGFRA has been shown to be commonly altered in high-grade gliomas (HGGs), including histone 3 lysine 27-mutated diffuse midline gliomas (H3K27M DMG), a disease with almost no long-term survivors. Here, we performed comprehensive genomic and transcriptomic analysis of 260 high-grade glioma cases, which revealed PDGFRA genomic alterations (mutations and/or amplifications) in 13% of patients. H3K27M DMGs had significantly higher PDGFRA expression compared to H3 wild-type tumors, and PDGFRA gene amplification resulted in even higher expression levels in H3K27M DMGs as well as H3 wild-type HGGs. We tested a panel of patient- derived pHGG/H3K27M DMG models against a range of PDGFRA inhibitors, including avapritinib, a potent small molecule inhibitor with relatively selective activity against both wild-type and mutant PDGFRA. Avapritinib showed supra-micromolar blood-brain barrier penetration in our pre-clinical models and demonstrated significant survival impact in an aggressive patient-derived H3K27M DMG mouse xenograft model. Finally, building on this preclinical activity, we report here the first clinical experience using avapritinib in eight pediatric and young adult patients with high-grade glioma (H3K27M DMG and/or PDGFRA altered). Avapritinib has thus far been well tolerated with no significant acute toxicities. Most importantly, our preliminary data reveal radiographic response evaluated by RAPNO criteria in 50% of patients, a striking outcome rarely seen in this patient population. In summary, we report that avapritinib is a selective, CNS-penetrant small molecule inhibitor of PDGFRA that shows potent activity in preclinical models and produces promising clinical responses with good tolerability in patients with high-grade glioma. This suggests a promising role for avapritinib therapy in this population with previously dismal outcomes.

Citation Format: Lisa Mayr, Maria Trissal, Kallen Schwark, Jenna Labelle, Andrew Groves, Julia Furtner-Srajer, Jeffrey Supko, Liesa Weiler-Wichtl, Olivia Hack, Jacob Rozowsky, Joana G. Marques, Eshini Pandatharatna, Ulrike Leiss, Verena Rosenmayr, Frank Dubois, Noah F. Greenwald, Sibylle Madlener, Armin S. Guntner, Hana Pálová, Natalia Stepien, Daniela Lötsch-Gojo, Christian Dorfer, Karin Dieckmann, Andreas Peyrl, Amedeo A. Azizi, Alicia Baumgartner, Ondřej Slabý, Petra Pokorná, Pratiti Bandopadhayay, Rameen Beroukhim, Keith Ligon, Christof Kramm, Annika Bronsema, Simon Bailey, Ana Guerreiro Stücklin, Sabine Mueller, David T. Jones, Natalie Jäger, Jaroslav Štěrba, Leonhard Müllauer, Christine Haberler, Chandan Kumar-Sinha, Arul Chinnaiyan, Rajen Mody, Mary Skrypek, Nina Martinez, Daniel C. Bowers, Carl Koschmann, Johannes Gojo, Mariella Filbin. Clinical response to the PDGFRα inhibitor avapritinib in high-grade glioma patients. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5719.

A Primary Spinal Nongerminomatous Germ Cell Tumor With Multiple Intracranial Metastases in a Toddler

Central nervous system germ cell tumors (CNS-GCTs) comprise 4% of all pediatric CNS tumors, with one third being nongerminomatous GCT (CNS-NG-GCT) type. The majority of these tumors arise in the intracranial compartment with 20% having drop metastases in the spine. We present a rare case of a 2-year-old boy with a primary intradural-extramedullary NG-GCT arising from the lumbosacral spine with a trifecta of unfavorable features, that is, young age, alpha-feto protein >1000 ng/mL, and disseminated disease within the cranium. Owing to his young age, he was treated with chemotherapy alone, avoiding radiation. His tumor marker (alpha-feto protein) declined from 8468 to 10 k-U/L over 8 weeks, and he remained in remission at the last follow-up. This atypical presentation of an intradural-extramedullary tumor with cranial dissemination in a childhood NG-GCT has yet to be described in the literature. Here we use this opportunity to highlight the treatment strategies and challenges in this unique clinical case.

Outcomes of Infants and Young Children With Relapsed Medulloblastoma After Initial Craniospinal Irradiation-Sparing Approaches: An International Cohort Study

PURPOSE

Infant and young childhood medulloblastoma (iMB) is usually treated without craniospinal irradiation (CSI) to avoid neurocognitive late effects. Unfortunately, many children relapse. The purpose of this study was to assess salvage strategies and prognostic features of patients with iMB who relapse after CSI-sparing therapy.

METHODS

We assembled a large international cohort of 380 patients with relapsed iMB, age younger than 6 years, and initially treated without CSI. Univariable and multivariable Cox models of postrelapse survival (PRS) were conducted for those treated with curative intent using propensity score analyses to account for confounding factors.

RESULTS

The 3-year PRS, for 294 patients treated with curative intent, was 52.4% (95% CI, 46.4 to 58.3) with a median time to relapse from diagnosis of 11 months. Molecular subgrouping was available for 150 patients treated with curative intent, and 3-year PRS for sonic hedgehog (SHH), group 4, and group 3 were 60%, 84%, and 18% (P = .0187), respectively. In multivariable analysis, localized relapse (P = .0073), SHH molecular subgroup (P = .0103), CSI use after relapse (P = .0161), and age ≥ 36 months at initial diagnosis (P = .0494) were associated with improved survival. Most patients (73%) received salvage CSI, and although salvage chemotherapy was not significant in multivariable analysis, its use might be beneficial for a subset of children receiving salvage CSI < 35 Gy (P = .007).

CONCLUSION

A substantial proportion of patients with relapsed iMB are salvaged after initial CSI-sparing approaches. Patients with SHH subgroup, localized relapse, older age at initial diagnosis, and those receiving salvage CSI show improved PRS. Future prospective studies should investigate optimal CSI doses and the role of salvage chemotherapy in this population.

Applying machine learning classifiers to automate quality assessment of paediatric dynamic susceptibility contrast (DSC-) MRI data

OBJECTIVE

Investigate the performance of qualitative review (QR) for assessing dynamic susceptibility contrast (DSC-) MRI data quality in paediatric normal brain and develop an automated alternative to QR.

METHODS

1027 signal-time courses were assessed by Reviewer 1 using QR. 243 were additionally assessed by Reviewer 2 and % disagreements and Cohen's κ (κ) were calculated. The signal drop-to-noise ratio (SDNR), root mean square error (RMSE), full width half maximum (FWHM) and percentage signal recovery (PSR) were calculated for the 1027 signal-time courses. Data quality thresholds for each measure were determined using QR results. The measures and QR results trained machine learning classifiers. Sensitivity, specificity, precision, classification error and area under the curve from a receiver operating characteristic curve were calculated for each threshold and classifier.

RESULTS

Comparing reviewers gave 7% disagreements and κ = 0.83. Data quality thresholds of: 7.6 for SDNR; 0.019 for RMSE; 3 s and 19 s for FWHM; and 42.9 and 130.4% for PSR were produced. SDNR gave the best sensitivity, specificity, precision, classification error and area under the curve values of 0.86, 0.86, 0.93, 14.2% and 0.83. Random forest was the best machine learning classifier, giving sensitivity, specificity, precision, classification error and area under the curve of 0.94, 0.83, 0.93, 9.3% and 0.89.

CONCLUSION

The reviewers showed good agreement. Machine learning classifiers trained on signal-time course measures and QR can assess quality. Combining multiple measures reduces misclassification.

ADVANCES IN KNOWLEDGE

A new automated quality control method was developed, which trained machine learning classifiers using QR results.

Towards zero percent treatment abandonment of patients with common and curable childhood cancer types in Blantyre, Malawi

BACKGROUND

Treatment abandonment is a common cause of treatment failure in low-income countries (LIC). We implemented a comprehensive package of interventions aiming to enable all families to complete the treatment of their child. The objective of this study was to evaluate the impact of those interventions.

PROCEDURE

In this prospective and historically controlled study, we included all children younger than 16 years with a newly diagnosed common and curable cancer type (acute lymphoblastic leukaemia [ALL], Hodgkin disease, Wilms tumour, retinoblastoma and Burkitt lymphoma) admitted to the Queen Elizabeth Central Hospital in Blantyre, Malawi, between 1 June 1 2019 and 1 June 1 2020. Interventions to enable treatment completion included full funding of costs to the family (treatment, transport, accommodation and food in the hospital) and tracking of patients if they did not attend treatment appointments. The outcomes of patients were compared with those of a similar historical cohort.

RESULTS

The intervention cohort of 150 patients were compared to 264 historical control patients. Treatment abandonment decreased significantly from 19% (49/264) to 7% (10/150) (p < .001). The proportion of patients with Wilms tumour, retinoblastoma or ALL alive without evidence of disease at the end of treatment increased from 38% (57/149) to 53% (44/83) (p = .03).

CONCLUSION

A simple and relatively low-cost comprehensive intervention package with no costs for families, significantly decreased treatment abandonment. This strategy may increase survival of children with common and curable cancers in LIC, especially when coupled with improvements in access to treatment and quality of treatment, including supportive care.

Abstract B37: PLX-4107, a selective IKZF2 degrader, reprograms suppressive regulatory T cells and demonstrates anti-tumor activity

Immune checkpoint therapy has demonstrated durable clinical responses in multiple solid tumor types. Reduced clinical response to checkpoint therapy has been linked to the presence of potent immunosuppressive regulatory T cells (Tregs) within the tumor microenvironment that contribute to tumor immune evasion. The transcription factor Helios (IKZF2) is a marker of highly suppressive Tregs and is required to maintain a stable, suppressive Treg cell phenotype in the inflammatory tumor microenvironment. Depletion of IKZF2 in Tregs results in both loss of suppressive activity and conversion of Tregs into effector-like T cells, leading to anti-tumor immunity. Targeted protein degradation using the endogenous Ubiquitin Proteasome System (UPS) has enabled targeting undruggable proteins, such as IKZF2, that have no known small molecule binding pocket. We have designed small molecules that promote a novel interaction between IKZF2 with the E3 ubiquitin ligase substrate receptor, Cereblon, leading to proximity induced protein degradation. PLX-4107 is a novel molecular glue that is a highly selective, potent, and rapid degrader of IKZF2 via the redirection of the E3 substrate receptor, Cereblon. Degradation of IKZF2 by PLX-4107 is blocked in the presence of proteasome and neddylation inhibitors as well as a Cereblon knock-out cell line, confirming that degradation is mediated by the UPS and specifically through the involvement of Cereblon. Proteome-wide analysis demonstrated that PLX-4107 selectively depletes IKZF2 protein levels without degrading other known Cereblon neo-substrates. In vitro, PLX-4107 mediated degradation of IKZF2 resulted in conversion of suppressive Tregs into CD4+ effector-like T cells, coupled with an increased production of the effector cytokines IL2 and IFNg. Oral administration of PLX-4107 to cynomolgus monkeys demonstrated sustained pharmacodynamic response, persistent depletion of IKZF2, and reprogramming of Tregs, consistent with the catalytic mechanism of protein degradation. In vivo, T cell expansion studies showed that administration of PLX-4107 decreased both Treg CD25 expression and proliferation, along with increased activation of CD8+ T effector cells. PLX-4107 was evaluated in in vivo xenograft efficacy studies and demonstrated dose dependent single agent anti-tumor activity that was dependent on the presence of T cells. In addition, co-administration of PLX-4107 and anti-PD-1 antibody Pembrolizumab resulted in tumor growth inhibition and significant combination benefit. PLX-4107 is a novel molecular glue that selectively degrades the undruggable transcription factor, IKZF2. PLX-4107 mediated IKZF2 degradation results in conversion of Tregs to an effector-like T cell phenotype, single agent antitumor activity and the ability to enhance the efficacy of immune checkpoint therapy in vivo.

Citation Format: Peggy A Thompson, Pengyu Yang, Linette Yang, Susan Song, Yujun Huang, Xiaoming Li, Alejandro Dearie, Stephen Chien, Mary E Spalding, Gabrielle Blanco, Elizabeth Daniele, Julia Toth, Aleksandar Jamborcic, Gregory Parker, Simon Bailey. PLX-4107, a selective IKZF2 degrader, reprograms suppressive regulatory T cells and demonstrates anti-tumor activity [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy; 2022 Oct 21-24; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(12 Suppl):Abstract nr B37.

CTNI-68. FIREFLY-1 (PNOC026): PHASE 2 STUDY OF PAN-RAF INHIBITOR TOVORAFENIB IN PEDIATRIC AND YOUNG ADULT PATIENTS WITH RAF-ALTERED RECURRENT OR PROGRESSIVE LOW-GRADE GLIOMA OR ADVANCED SOLID TUMORS

BACKGROUND

RAF alterations are oncogenic drivers found in most pediatric low-grade gliomas (LGGs). Tovorafenib is an investigational, oral, selective, CNS-penetrant, small molecule, type II pan‑RAF inhibitor.

METHODS

FIREFLY-1 (NCT04775485) is a multicenter phase 2 study evaluating the safety and efficacy of tovorafenib monotherapy. Registrational arm 1 enrolled patients with recurrent/progressive LGG harboring an activating BRAF alteration. Patients aged 6 months–25 years who progressed following ≥ 1 prior line of systemic therapy were eligible. Tovorafenib 420 mg/m2 (≤ 600 mg) was administered weekly (tablet or liquid suspension formulation) until progression or for ≥ 26, 28-day cycles. The primary endpoint (arm 1) was overall response rate, as defined by RANO criteria, per independent review.

RESULTS

As of April 14, 2022, 25 patients were enrolled to arm 1 and had ≥ 6 months of follow-up. Median age at enrollment was 8 years (range 3–18). Most patients had astrocytomas (92%), 48% with optic pathway involvement. Patients were heavily pretreated (56% with ≥ 3 prior lines of therapy), and 72% previously received MAPK pathway-targeted agents. Tumors harbored BRAF fusions (84%) or BRAF V600E mutations (16%). Per independent assessment, partial responses (1 unconfirmed) were seen in 14 (64%) of 22 evaluable patients, with 6 additional patients having stable disease, and a clinical benefit rate of 91%. Responses were achieved in tumors with BRAF fusions and V600E mutations. Most treatment-emergent adverse events (AEs) were grade 1 or 2 (96%). The most common grade ≥ 3 AEs were anemia (12%), vomiting, increased blood creatinine phosphokinase and maculopapular rash (8% each). Seven patients (28%) required dose modification for treatment-related AEs; no patients discontinued tovorafenib due to AEs. Updated results, including efficacy per RAPNO assessments will be presented.

CONCLUSIONS

Tovorafenib was generally well tolerated and showed encouraging evidence of antitumor activity in children with pretreated BRAF-altered LGG.

Epigenetic regulator genes direct lineage switching in MLL/AF4 leukemia

The fusion gene MLL/AF4 defines a high-risk subtype of pro-B acute lymphoblastic leukemia. Relapse can be associated with a lineage switch from acute lymphoblastic to acute myeloid leukemia, resulting in poor clinical outcomes caused by resistance to chemotherapies and immunotherapies. In this study, the myeloid relapses shared oncogene fusion breakpoints with their matched lymphoid presentations and originated from various differentiation stages from immature progenitors through to committed B-cell precursors. Lineage switching is linked to substantial changes in chromatin accessibility and rewiring of transcriptional programs, including alternative splicing. These findings indicate that the execution and maintenance of lymphoid lineage differentiation is impaired. The relapsed myeloid phenotype is recurrently associated with the altered expression, splicing, or mutation of chromatin modifiers, including CHD4 coding for the ATPase/helicase of the nucleosome remodelling and deacetylation complex. Perturbation of CHD4 alone or in combination with other mutated epigenetic modifiers induces myeloid gene expression in MLL/AF4+ cell models, indicating that lineage switching in MLL/AF4 leukemia is driven and maintained by disrupted epigenetic regulation.

How Can Genomic Innovations in Pediatric Brain Tumors Transform Outcomes in Low- and Middle-Income Countries?

Pragmatic ways to apply molecular innovation to childhood brain cancer diagnosis and therapy in LMICs

A Nationwide Evaluation of Bevacizumab-based Treatments in Paediatric Low-Grade Glioma in the UK: Safety. Efficacy, Visual Morbidity and Outcomes

BACKGROUND

Bevacizumab is increasingly used in children with Paediatric Low-Grade Glioma (PLGG) despite limited evidence. A nationwide UK service evaluation was conducted to provide larger cohort 'real life' safety and efficacy data including functional visual outcomes.

METHODS

Children receiving Bevacizumab-based treatments (BBT) for PLGG (2009-2020) from 11 centres were included. Standardised neuro-radiological (RANO-LGG) and visual (logMAR visual acuity) criteria were used to assess clinical-radiological correlation, survival outcomes and multivariate prognostic analysis.

RESULTS

Eighty-eight children with PLGG received BBT either as 3 rd line with Irinotecan (85%) or alongside 1 st/2 nd line chemotherapies (15%). Toxicity was limited and minimal. Partial response (PR, 40%), stable disease (SD, 49%), and progressive disease (PD, 11%) were seen during BBT. However, 65% progressed at 8 months (median) from BBT cessation, leading to a radiology-based 3yr-progression-free survival (PFS) of 29%. Diencephalic syndrome (p= 0.03) was associated with adverse PFS. Pre-existing visual morbidity included unilateral (25%) or bilateral (11%) blindness. Improvement (29%) or stabilisation (49%) of visual acuity were achieved, more often in patients' best eyes. Vision deteriorated during BBT in 14 (22%), with 3-year visual-PFS of 53%; more often in patients' worst eyes. A superior visual outcome (p=0.023) was seen in Neurofibromatosis type 1-associated Optic Pathway Glioma (OPG). Concordance between visual and radiological responses was 36%; optimised to 48% using only best eye responses.

CONCLUSIONS

BBTs provide effective short-term PLGG control and delay further progression, with a better sustained visual (best >worst eye) than radiological response. Further research could optimise the role of BBTs towards a potentially sight-saving strategy in OPG.

Esophageal cooling during ablation of persistent atrial fibrillation is associated with improved freedom from arrhythmia at one-year follow up

Background

Various factors influence successful freedom from atrial arrhythmia after pulmonary vein isolation (PVI) with radiofrequency (RF) ablation for the treatment of atrial fibrillation (AF). Lesion transmurality and continuity (as measured by the Continuity Index) are two important factors, and these can be worsened by pauses in RF energy application due to esophageal overheating. Proactive esophageal cooling precludes the need for premature cessation of power, avoiding partially-formed lesions and the need to “hop-scotch” in the left atrium. The resulting improvement in lesion continuity may improve long-term freedom from atrial arrhythmia after PVI, particularly in patients with persistent AF, where more posterior wall ablation is often necessary.

Purpose

Determine differences in freedom from arrhythmia at one year between patients receiving LET monitoring and those receiving esophageal cooling during PVI for persistent AF.

Methods

We reviewed data from two healthcare systems for patient rhythm status at one-year follow up after PVI for the treatment of persistent or long-standing persistent AF. We then determined Kaplan-Meier estimates of freedom from arrhythmia (AF, atrial flutter, and atrial tachycardia), and compared these between patients receiving esophageal cooling and those treated with traditional LET monitoring.

Results

A total of 252 patients received PVI for persistent or long-standing persistent AF and had data available for review. Of these, 148 received LET monitoring (with either a single or multi-sensor temperature probe), and 104 received active cooling with a dedicated esophageal cooling device. Mean age and gender for each group was similar (67.2, range 21 to 88 years, 36% female for LET monitoring, and 67.8, range 32 to 89 years, 30% female for esophageal cooling). KM estimates for freedom from AF at the one-year follow-up were 44.2% for LET monitored patients and 79.3% for actively cooled patients (P=0.01).

Conclusions

Freedom from atrial arrhythmia at one-year after PVI for persistent AF is associated with significant improvement when using active esophageal cooling rather than LET monitoring.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Attune Medical

The impact of bone mineral density screening on incident fractures and healthcare resource utilization among postmenopausal breast cancer survivors treated with aromatase inhibitors

Bone mineral density screening prior to initiating aromatase inhibitor therapy was associated with lower incident bone fractures and healthcare resource utilization among postmenopausal breast cancer survivors.

INTRODUCTION

Postmenopausal women with hormone receptor-positive breast cancer (BC) often receive aromatase inhibitor (AI) therapy. However, AIs induce bone loss and BC survivors are at an increased risk of bone fractures. This study determined whether receipt of baseline dual-energy x-ray absorptiometry (DXA) screening is associated with decreased incident fractures and lower healthcare resource utilization.

METHODS

We retrospectively analyzed 22,713 stage 0-III primary BC survivors who received AI therapy ≤ 1 year prior to BC diagnosis from the Medicare-Linked Surveillance, Epidemiology, and End-Results database. We categorized DXA screening for those who had a procedural claim within 12 months prior through 6 months after first AI claim. We used propensity score methods to assess the association of DXA screening with bone fractures and health resource utilization.

RESULTS

Of the study cohort, 62% received a DXA screening. Women with comorbid dementia, renal disease, and congestive heart failure were less likely to receive a DXA. After adjusting for confounders, BC survivors who received a DXA had a 32% decreased risk of any bone fracture compared to those who did not (hazard ratio (HR): 0.68, 95% confidence interval (CI): 0.60-0.76, p < 0.001). Similarly, those who received a DXA were less likely to be hospitalized (HR 0.73 (0.62-0.86)) or use outpatient services (HR 0.85 (0.74-0.97)).

CONCLUSIONS

Bone density screening is associated with decreased incident bone fractures and a lower likelihood of utilizing healthcare resource for fracture-related events. Postmenopausal BC survivors treated with AIs should undergo appropriate bone density screening to reduce morbidity, mortality, and health care expenses.

Medulloblastoma group 3 and 4 tumors comprise a clinically and biologically significant expression continuum reflecting human cerebellar development

Medulloblastoma is currently subclassified into distinct DNA methylation subgroups/subtypes with particular clinico-molecular features. Using RNA sequencing (RNA-seq) in large, well-annotated cohorts of medulloblastoma, we show that transcriptionally group 3 and group 4 medulloblastomas exist as intermediates on a bipolar continuum between archetypal group 3 and group 4 entities. Continuum position is prognostic, reflecting a propensity for specific DNA copy-number changes, and specific switches in isoform/enhancer usage and RNA editing. Examining single-cell RNA-seq (scRNA-seq) profiles, we show that intratumoral transcriptional heterogeneity along the continuum is limited in a subtype-dependent manner. By integrating with a human scRNA-seq reference atlas, we show that this continuum is mirrored by an equivalent continuum of transcriptional cell types in early fetal cerebellar development. We identify distinct developmental niches for all four major subgroups and link each to a common developmental antecedent. Our findings show a transcriptional continuum arising from oncogenic disruption of highly specific fetal cerebellar cell types, linked to almost every aspect of group 3/group 4 molecular biology and clinico-pathology.

Development and operation of the defence COVID-19 lab as a SARS-CoV-2 diagnostic screening capability for UK military personnel

BACKGROUND

In the face of the COVID-19 pandemic, the Defence Science and Technology Laboratory (Dstl) and Defence Pathology combined to form the Defence Clinical Lab (DCL), an accredited (ISO/IEC 17025:2017) high-throughput SARS-CoV-2 PCR screening capability for military personnel.

LABORATORY STRUCTURE AND RESOURCE

The DCL was modular in organisation, with laboratory modules and supporting functions combining to provide the accredited SARS-CoV-2 (envelope (E)-gene) PCR assay. The DCL was resourced by Dstl scientists and military clinicians and biomedical scientists.

LABORATORY RESULTS

Over 12 months of operation, the DCL was open on 289 days and tested over 72 000 samples. Six hundred military SARS-CoV-2-positive results were reported with a median E-gene quantitation cycle (Cq) value of 30.44. The lowest Cq value for a positive result observed was 11.20. Only 64 samples (0.09%) were voided due to assay inhibition after processing started.

CONCLUSIONS

Through a sustained effort and despite various operational issues, the collaboration between Dstl scientific expertise and Defence Pathology clinical expertise provided the UK military with an accredited high-throughput SARS-CoV-2 PCR test capability at the height of the COVID-19 pandemic. The DCL helped facilitate military training and operational deployments contributing to the maintenance of UK military capability. In offering a bespoke capability, including features such as testing samples in unit batches and oversight by military consultant microbiologists, the DCL provided additional benefits to the UK Ministry of Defence that were potentially not available from other SARS-CoV-2 PCR laboratories. The links between Dstl and Defence Pathology have also been strengthened, benefitting future research activities and operational responses.

Fast investigative lung cancer pathway and endobronchial ultrasound procedure supported by rapid on-site evaluation

INTRODUCTION

EBUS is a well-established tool for diagnosis and staging of lung cancer in a fast track investigative pathway. However, impact of ROSE in conjunction with EBUS on reduction of time to treatment decision (TTD) for cancer patients is less well known.

AIMS

Our aim was to determine TTD which was defined as the number of working days from EBUS procedure to the discussion at sector lung multidisciplinary team meeting (MDT). Moreover, concordance of ROSE with final diagnosis was evaluated.

METHODS

A retrospective analysis was performed of a prospective data collection in a busy teaching hospital over a four months study period (September to December 2018).

RESULTS

Data from 112 patients was analyzed. There were 61 (54%) males. Mean age was of 70 years (range 43-91). WHO performance status was 0 in 20 (23%), 1 in 57 (51%), 2 in 22 (20%) and 3 in 7 (6%) patients. In total 522 needle passes were performed from 242 sampling sites. Average working days to discuss at MDT after optimal EBUS sampling was 2.087 (range 0-13 working days). ROSE concordance with final cytological diagnosis was 98.4%. The number of needle passes per site for adequate sample and diagnosis in malignant (4.929) vs non-malignant (2.776) involvement was significantly different (p value <0.0001). There was 100% sample adequacy for preliminary diagnosis, immunohistochemistry and predictive molecular testing.

CONCLUSION

ROSE supported fast-investigative pathway by reducing the time to treatment decision (TTD) making at MDT. High concordance with final cytological diagnosis makes it an effective tool to inform meaningful decision making.

P-363 Systematic review and meta-analysis of female lifestyle factors and risk of recurrent pregnancy loss (RPL)

Study question

What is the impact of female lifestyle (BMI, smoking, caffeine, alcohol) on RPL in the general population and on further miscarriage in the RPL population?

Summary answer

Being underweight and BMI&gt;25 contributes significantly to increased risk of RPL (general population). BMI&gt;25 or BMI&gt;30 increases the risk of further miscarriages (RPL population)

What is known already

Lifestyle factors are modifiable and in many instances lifestyle optimisation enhances the chances of a positive reproductive outcome. Whilst the specific mechanisms leading to early pregnancy loss is still relatively unknown, poor lifestyle is associated with a hostile reproductive environment whereby optimal embryo implantation and securement of a pregnancy is compromised. The peri-implantation intrauterine environment is a key determinant of pre-implantation embryo development and early programming. RPL is a complex disease where causation has been attributed to numerous factors and whilst it is known that lifestyle factors affect sporadic miscarriage, the extent of this on RPL is less well known.

Study design, size, duration

A systematic review and meta-analysis was performed to assess the associations between lifestyle factors and RPL. Studies that analysed RPL in the context of BMI, smoking, alcohol and caffeine intake were included. The primary and secondary outcomes were odds of having RPL in the general population and odds of further miscarriage, respectively.

Participants/materials, setting, methods

Studies were included if they explored women of reproductive age who had been exposed to an aspect of female lifestyle. We excluded studies which assessed the effectiveness of an intervention aimed at altering lifestyle and studies which assessed lifestyle factors in the context of IVF outcomes or associations with PCOS. We screened all studies, reviewing full papers where required and disregarding those that did not meet the eligibility criteria using a double-blind approach.

Main results and the role of chance

The systematic search identified a total of 24, 705 records and an additional 194 records through hand-searching of references. 16 studies were included in this systematic review and meta-analysis. None of these studies were RCTs; there were 8 case control studies, 6 cohort studies, 1 survey-based study and 1 cross-sectional study.

Underweight and women with BMI &gt; 25 are at higher odds of RPL in the general population (OR 1.2, 95% CI 1.12–1.28 and OR 1.21, 95% CI 1.06–1.38, respectively). In women with RPL, having BMI &gt; 30 and BMI &gt; 25 has increased odds of further miscarriages (OR 1.77, 95% CI 1.25–2.50 and OR 1.35, 95% CI 1.07–1.72, respectively).

The odds of RPL in the general population is increased in women who were cigarette smokers compared to non-smokers but this is not statistically significant (OR 1.62, 95% CI 0.90–2.93). Alcohol intake compared with no alcohol intake increases the risk of RPL, however this is not statistically significant (OR 1.12, 95% CI 0.88–1.44). The odds of RPL in the higher caffeine intake group (&gt;99mg/day) compared to the lower caffeine intake group (≤99mg/day) is higher but not significant (OR 1.35, 95% CI 0.83–2.19).

Limitations, reasons for caution

The quality of the evidence was low or very low, mainly due to heterogeneity in study populations. There were inconsistencies in the definition of RPL, some studies included women with ‘≥3 consecutive miscarriages’, others ‘≥2 miscarriages’. We did not explore the impact of male lifestyle on the risk of RPL.

Wider implications of the findings

Being underweight and BMI&gt;25 contributes significantly to increased risk of RPL. BMI&gt;25 or BMI&gt;30 increases the risk of further miscarriages in the RPL population. Studies addressing the effects of alcohol, cigarette smoking and caffeine on the risk of RPL with optimisation of BMI in this cohort of women are warranted.

Trial registration number

Is the frequency of low plasma-mannose-binding lectin (p-MBL) levels increased in recurrent pregnancy loss (RPL) after spontaneous conception or IVF/ICSI and recurrent implantation failure (RIF)?

Abstract 421: PLX-3618, a potent, selective monovalent BRD4 degrader demonstrates activity in models of prostate cancer

Prostate cancer is the second most common cause of cancer related deaths in men in the United States. Pathogenesis is driven by the androgen receptor (AR), which has led to front-line treatment modalities that are based on androgen deprivation therapy (ADT). About 10-20% of all prostate cancers evolve to resist ADT and are classified as castration-resistant prostate cancer (CRPC) indicating the continued need for new treatment options. Bromodomain-containing protein 4 (BRD4) is an acetylated-chromatin associating protein that is involved in transcriptional elongation, mRNA splicing, epigenetic bookmarking, and super-enhancer activity. The BRD4 protein has been shown to both bind and colocalize with AR at androgen response elements (AREs) on chromatin. Furthermore, elevated BRD4 expression is prognostic of increased prostate specific antigen (PSA) levels following radical prostatectomy and is correlated with higher Gleason scores and poor overall survival. The intertwined activity of BRD4 with multiple essential driver mechanisms of prostate cancer suggests it may be a key target for developing novel therapeutics. Using our ultra-high throughput cell-based screening platform, which directly measures degradation of pathogenic proteins upon exposure to diverse chemical libraries, we identified a series of novel monovalent BRD4 degraders that was optimized to produce our lead compound PLX-3618. A cancer cell panel screen for antiproliferative effects of PLX-3618 indicated enhanced sensitivity in subsets of prostate cancer lines. PLX-3618 elicited selective, rapid, and deep degradation of BRD4 protein in prostate cancer cell models, without degrading the closely related BRD2 and BRD3 proteins. Addition of either proteosome or neddylation inhibitors blocked BRD4 degradation indicating a ubiquitin-proteosome system mediated clearance mechanism. Degradation of BRD4 led to sustained multimodal inhibition of the AR pathway and disruption of key oncogene enhancer networks. When compared to pan-BET inhibitors, treatment of select prostate cancer cell lines with PLX-3618 resulted in increased levels of the tumor suppressors p53 and p21, an aberrant DNA damage response, and substantially amplified apoptosis. Finally, in in vivo preclinical models of prostate cancer, PLX-3618 showed far superior efficacy over a pan-BET inhibitor. Taken together, the selective degradation of BRD4 via the potent monovalent degrader PLX-3618 represents a novel strategy in treating prostate cancer.

Citation Format: Kenneth Steadman, Gregory S. Parker, Geoffray Leriche, Sarah Fish, Julia Toth, Mary E. Spalding, Elizabeth Daniele, Aleksandar Jamborcic, Xiaoming Li, E Adam Kallel, Farhana Barmare, Kenneth Chng, Erika Green, Michael Hocker, Elliot Imler, Yi Zhang, Peggy A. Thompson, Simon Bailey. PLX-3618, a potent, selective monovalent BRD4 degrader demonstrates activity in models of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 421.

Abstract 1111: Identification of selective IKZF2 degraders that reprogram suppressive regulatory T cells in solid tumors

Targeted protein degradation (TPD) using the endogenous Ubiquitin Proteasome System (UPS) is a rapidly growing drug discovery strategy to eliminate pathogenic proteins. Molecular glues are small molecules that promote a novel interaction between a protein of interest with an E3 ubiquitin ligase leading to proximity induced protein degradation. This has enabled targeting undruggable proteins, such as the zinc-finger transcription factor Helios (IKZF2), that have no known small molecule binding pocket.

Despite recent clinical breakthroughs in checkpoint blockade in treating solid tumors, suppression of the antitumor immune response in the tumor microenvironment (TME) is a major obstacle to tumor regression. Regulatory T cells (Tregs) in the TME are potent immunosuppressive cells that promote progression of cancer. IKZF2 has been shown to be a marker of highly suppressive Treg cells and is critical for maintaining the anergic and suppressive phenotype in the highly inflammatory tumor microenvironment. Genetic depletion of IKZF2 in Treg cells results in both loss of suppressive activity and conversion of Tregs into T effector cells, leading to enhanced anti-tumor immunity. Collectively, these findings support that an IKZF2-specific degrader could be beneficial in enhancing the efficacy of current immunotherapies.

Here we report our efforts leading to the development of a series of potent and selective IKZF2 degraders for the treatment of cancer. Our lead compound, PLX-4107, is a novel molecular glue that was optimized to be a highly selective, deep, and rapid IKZF2 degrader via the redirection of the E3 substrate receptor, cereblon. Proteome-wide analysis demonstrated that PLX-4107 depletes IKZF2 protein levels without degrading other known cereblon neo-substrates. PLX-4107 mediated degradation of IKZF2 resulted in conversion of highly suppressive Tregs into T effector cells, coupled with an increased expression of the effector cytokines IL2 and IFNγ. Oral administration of PLX-4107 to cynomolgus monkeys caused rapid, complete, and prolonged degradation of IKZF2 in Tregs, indicative of the catalytic nature of degraders where sustained pharmacodynamic response is observed well beyond plasma drug exposure levels. These preliminary data provide a strong rationale for developing small molecule therapeutics that target the undruggable IKZF2 transcription factor with the potential to enhance the efficacy of immune checkpoint therapy.

Citation Format: Peggy A. Thompson, Pengyu Yang, Xiaoming Li, Stephen Chien, Mary E. Spalding, Alejandro Dearie, Elizabeth Daniele, Linette Yang, E Adam Kallel, Aleksandar Jamborcic, Julia Toth, Gregory Parker, Simon Bailey. Identification of selective IKZF2 degraders that reprogram suppressive regulatory T cells in solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1111.

MEDB-43. Development of a bioinformatics pipeline for identification of differential DNA methylation events associated with medulloblastoma relapse

Relapsed medulloblastoma (rMB) is treatment-resistant and fatal in ~95% of cases. The epigenetic features of rMB, and any role as drivers of disease relapse/treatment-resistance have yet to be investigated. We therefore developed a pipeline to identify differentially methylated CpGs (DM-CpGs) and regions (DMRs) in a paired-rMB cohort. Our paired-rMB cohort (n=61, relapsed tumours matched with diagnosis counterparts) with available Illumina Methylation 450K/850K microarray data was processed in R-Studio. The packages Limma and DMRcate were used to perform a paired differential methylation analysis on a filtered selection of array probes (n=335,767), identifying DM-CpGs and DMRs with a 5% FDR. DMRs were further retained if they had a maximum-Δβ of >0.2 and correlated with locus-specific gene expression in a separate paired DNA-methylation array/RNA-seq cohort from medulloblastoma diagnosis samples (n=202). Finally, we created univariable Cox models to assess the prognostic potential of DM-CpGs/DMRs in an independent survival cohort of medulloblastoma diagnosis samples (n=498). Across the paired-rMB cohort, there were few significant differential methylation events initially identified at relapse (n=258 DM-CpGs, n=32 DMRs). Upon sub-analysis by molecular group, MB_Group4 (n=18 pairs) alone yielded significant findings (n=189 DM-CpGs, n=26 DMRs). Most changes involved hypermethylation events detected at relapse. Multiple DM-CpGs identified at relapse were prognostic for both overall and event-free survival when assessed in our independent cohort (n=22 whole cohort, n=13 Group 4, BH-adjusted p<0.05). When applying the DMR filters, only the MB_Group4 DMRs passed the Δβ filter (n=18/26), with few correlating with gene expression (n=2, p<0.001), and none demonstrating prognostic significance. This pipeline facilitates exploration of the clinical relevance of epigenome-wide changes in a paired-rMB cohort. We highlight the potential prognostic significance of DM-CpGs, and future work will explore the potential functional role of candidate-genes associated with our DMRs, as novel drivers of rMB.

SWK-03. Neuroimaging in CNS tumours: To GA , or not to GA, that is the question

Children with a Central Nervous System (CNS) tumour have frequent magnetic resonance imaging (MRI) scans during their disease trajectory. Younger children routinely have these performed under general anaesthetic (GA) with an associated risk and inconvenience. Our project over a two-year period was to introduce a structured programme to any child over the age of five years old to achieve an MRI scan without the need for a GA. Thirty-six patients took part. The motivation behind this project was to enhance the hospital experience for patients and their families, lessen time spent in hospital and minimise risk. In addition, there was an added incentive of cost saving and increased availability of GA scans for other specialities within the hospital setting. During the COVID pandemic, it has also resulted in a reduction of our patients requiring COVID swabs, and isolation and in turn a reduction in aerosol generating procedures. As part of the structured programme, each child had an initial assessment with the nurse specialist followed by a minimum of one play preparation session with the play specialist. Children were required to demonstrate they could follow simple instructions, engage in social stories and role-play with hospital equipment and specialised resources. During these sessions, the children visited the MRI department where they practiced lying flat on the MRI bed as it moved into the scanner. Over the two-year period, of the total number of MRI scans performed, the amount of MRI scans requiring a GA reduced from 41% to 31%. The quality of the MRI scans was scrutinised and shown not to be significantly affected. In summary, by introducing a structured programme, it is possible to significantly reduce the need for GA in children requiring CNS imaging as part of their tumour journey.

MEDB-49. Relapsed SHH medulloblastomas in young children. Are there alternatives to full-dose craniospinal irradiation?

BACKGROUND/RATIONAL: Following initial irradiation sparing therapy, many young children with relapsed medulloblastoma can be salvaged with craniospinal irradiation (CSI). However, the interval to relapse is short and neurocognitive sequelae remain a major concern. The contribution of molecular subgrouping may help refine indications and modalities of salvage strategies in this population. METHOD: From a cohort of 151 young children with molecularly characterized relapsed medulloblastoma, subset analysis of the SHH medulloblastoma was conducted to describe the practice of salvage radiotherapy and associated post-relapse survival (PRS). RESULTS: Sixty-seven SHH medulloblastoma patients (46 M0; 54 GTR; 11 non-ND/MBEN) received salvage therapy with curative intent. Before relapse, 54 (80.6%) received conventional chemotherapy (CC), 13 (19.4%) high-dose chemotherapy (HDC), while seven had additional focal radiotherapy (fRT). Median time to relapse was 11.1 months (range 3.8-41.0) and 43.3% were localized. Thirty patients (16 localized relapse) underwent surgery. Forty-seven (71.2%) received salvage radiotherapy (20 with CC; 10 with HDC; 15 alone, two unknown). CSI and fRT accounted for 82% and 18% respectively. CSI median dose was 36Gy (range 18-39Gy). Ten patients (eight with localized relapse) received CSI doses ≤23.4Gy. Nineteen patients (28.8%) did not receive any radiotherapy (nine HDC; 10 CC only). Radiotherapy was associated with better 3-year PRS (73.0% versus 36.1%; p=0.001). All patients treated with CSI ≤ 23.4Gy were alive at median follow-up of 69 months(24-142). Six of nine patients treated with HDC without irradiation were alive at last follow-up. Sixty-three percent of patients received reduced dose CSI(≤23.4Gy), fRT, or no radiotherapy, and their PRS did not significantly differ from those who received CSI ≥ 30.6Gy (p = 0.54). CONCLUSION: While salvage CSI provided PRS benefit in this SHH medulloblastoma cohort, we report the use of reduced salvage radiotherapy and irradiation avoidance in 63% of the patients, with 60% alive at last follow-up.

MEDB-36. Clinical and molecular heterogeneity withinMYC andMYCN amplified medulloblastoma

MYC and MYCN are the most commonly amplified oncogenes in medulloblastoma. Their overall association with a poor prognosis has supported their adoption as high-risk disease biomarkers in trials. However, emerging evidence suggests that certain patients with MYN/MYCN focally-amplified tumours can achieve long-term survival and therefore may suffer unnecessary late-effects associated with intensified therapies. To investigate this heterogeneity, we characterised the molecular and clinico-pathological features of curated cohorts of MYC (n=64) and MYCN (n=95) amplified tumours, drawn from >1000 diagnostic cases, and assessed their associations with disease outcome. Within the MYCN-amplified cohort, survival was related to molecular group; patients with MYCN_Grp3 or MYCN_Grp4 tumours with no other clinico-pathological risk factors (subtotal resection (STR), metastatic disease, LCA pathology) were intermediate-risk (n=25;70% 5-year PFS). In contrast, a very-high-risk group was defined by positivity for MYCN_SHH, STR and/or LCA (n=64;32% 5-year PFS). 22/35 assessable MYCN_SHH harboured TP53 mutations; 9/12 with data were germline. MYC_Grp3 represented the majority (46/58; 79%) of molecularly-grouped MYC-amplified tumours. Importantly, while radiotherapy receipt conferred a modest survival advantage, for MYC-amplified tumours with additional clinico-molecular risk factors (LCA, metastasis, STR, Grp3), survival was dismal, irrespective of radiotherapy receipt. A very-high-risk group of MYC-amplified tumours was identified (n=51;10% 5-year PFS), defined by positivity for ≥1 additional risk factors (STR, LCA and/or metastasis). Alternatively, membership of subgroups II/V defined a smaller, very-high-risk patient group (n=28;7% 5-year PFS). Long-term survival was seen in the majority of remaining MYC-amplified tumours negative for these specified features (61% 5-year PFS; high-risk). MYC and MYCN-amplified medulloblastomas are biologically heterogeneous with diverse clinical outcomes. Molecular subgroup assignment and established clinical features are critical for their improved stratification. Patient subgroups identified may be eligible for therapy de-escalation; in contrast, the very-high-risk patient groups are incurable using current therapies and urgently require novel experimental treatment strategies upfront.

ATRT-20. Novel prognostic molecular signatures for improved risk-classification of Atypical Teratoid Rhabdoid Tumours

Malignant Rhabdoid Tumours (MRT) are aggressive paediatric malignancies seen in the central nervous system (Atypical Teratoid Rhabdoid Tumours (ATRT)), and kidney and other soft tissues (Extra-cranial Rhabdoid Tumours (ECRT)). With current therapies often proving ineffective and a lack of clear prognostic associations with consensus subgroups, we explored the possibility of using prognostic molecular signatures to further identify the biological characteristics of high risk ATRT patients. By employing a cross-validated feature selection method the methylation profiles of 121 MRT patients were analysed with clinical data to obtain meta-CpG signatures associated with prognosis for ATRT, ECRT and MRT. The relationship between these meta-CpG signatures and the consensus subgroups were further explored, along with the correlation of meta-CpGs with gene expression to establish biological significance. By selecting CpGs for their ability to predict survival this method obtained three novel prognostic methylation signatures which predict MRT outcome (ATRT-5, ECRT-14 and MRT-42). These signatures are independent of molecular subgroup and each signature was significantly associated with overall survival (OS) and event free survival (EFS) in their respective cohorts (p&lt;0.001). Both ATRT-5 and MRT-42 maintained their significant association with OS in an independent ATRT cohort (n=64) and each meta-CPG signature is prognostically independent of other major clinical risk factors (e.g. receipt of radiotherapy and presence of metastases). Biologically, individuals with high-risk methylation signatures showed a gene expression profile suggestive of higher proliferative rates and tumours with low-risk scores in ATRT-5 and MRT-42 had an upregulated inflammatory response and increased immune infiltration. Combining these meta-CpGs with other significant clinical risk-factors produced high performing multivariate Cox-models enabling us to propose new stratification models for ATRT and MRT patients. These subgroup-independent prognostic signatures represent a distinct biology in ATRT and, if validated in prospective studies, could progress the use and efficacy of precision-based medicine in this therapeutically challenging disease.

QOL-34. The relationship between Psychological Flexibility, Quality-of-Life and psychological health in young people who have experienced a brain tumour

Despite increasing survival rates in young people who have experienced a brain tumour, this patient group have the poorest reported quality-of-life (QoL) of all cancer survivors. QoL is defined as an individual’s perception of their position in life in relation to their goals, expectations and standards. QoL can be influenced by physical functioning but one of its strongest predictors is psychological health. A concept that has a large impact on psychological health is Psychological Flexibility (PF). PF refers to the ability to recognise and adapt to situations, shift cognitive and behavioural repertoires which are impacting negatively on personal and social functioning and commit to behaviours that are in line with strongly held values. Studies have demonstrated a relationship between PF and QoL in other patient populations such as chronic pain and breast cancer survivors. In this study we explored the relationship between PF and QoL at baseline in a sample of young people enrolled in a randomised controlled trial of Acceptance and Commitment Therapy (ACT) for young people who have experienced a brain tumour. We found that higher PF was associated with higher QoL in both 11-15 year olds (R2 = .69, p < .05) and 16 – 24 year olds (R2 = .29, p < .01). We also found higher PF was associated with lower levels of mental health difficulties (R2s ≥ .24, ps < .01) which was also associated with higher levels of QoL (R2 = .49 , p < .01). The results suggest assessing and providing support to increase PF is important for young people who have experienced a brain tumour. It highlights that interventions found to increase PF, such as ACT, could be helpful in improving psychological health in this population.