Social Anxiety Symptoms in Adolescents and Young Adults Recently Diagnosed with Cancer

Purpose: Social anxiety disorder (SAD) remains an understudied potential link between the cancer experience and adolescent and young adult (AYA) cancer survivors' poor psychosocial outcomes. We investigated the frequency and duration of, as well as factors associated with, symptoms of SAD among AYAs with cancer. Methods: This longitudinal, mixed-methods study involved online surveys (including a validated screening tool for SAD) at recruitment and 6 months later, and a structured clinical interview. Results: Twenty-eight AYAs (aged 12-30 years, <1-year postdiagnosis, 50% male) completed the first survey (M = 6 months postdiagnosis). About 32% reported clinically significant SAD symptoms. Fourteen completed the follow-up survey (M = 12 months postdiagnosis), of which 9 (62%) reported persistent or worse symptoms of SAD significantly associated with emotional distress, physical appearance concerns, negative social cognitions, and depression. Conclusion: A subset of AYAs with cancer may experience clinically significant SAD symptoms that can affect their psychosocial well-being. Further work on how to best identify and support AYAs with SAD is needed.

Guidelines for Caring for the Social Well-Being of Adolescents and Young Adults with Cancer in Australia

More than 1000 Australian adolescents and young adults (AYAs) are diagnosed with cancer annually. Many report unmet social well-being needs, which impact their mental health. Australian AYA cancer care providers lack guidance to address these needs well. We aimed to develop guidelines for caring for the social well-being of AYAs with cancer in Australia. Following the Australian National Health and Medical Research Council guidance, we formed a multidisciplinary working group (n = 4 psychosocial researchers, n = 4 psychologists, n = 4 AYA cancer survivors, n = 2 oncologists, n = 2 nurses, and n = 2 social workers), defined the scope of the guidelines, gathered evidence via a systematic review, graded the evidence, and surveyed AYA cancer care providers about the feasibility and acceptability of the guidelines. The guidelines recommend which AYAs should have their social well-being assessed, who should lead that assessment, when assessment should occur with which tools/measures, and how clinicians can address AYAs' social well-being concerns. A key clinician, who is knowledgeable about AYAs' developmental needs, should lead the assessment of social well-being during and after cancer treatment. The AYA Psycho-Oncology Screening Tool is recommended to screen for social well-being needs. The HEADSSS Assessment (Home, Education/Employment, Eating/Exercise, Activities/Peer Relationships, Drug use, Sexuality, Suicidality/Depression, Safety/Spirituality Assessment) can be used for in-depth assessment of social well-being, while the Social Phobia Inventory can be used to assess social anxiety. AYA cancer care providers rated the guidelines as highly acceptable, but discussed many feasibility barriers. These guidelines provide an optimal care pathway for the social well-being of AYAs with cancer. Future research addressing implementation is critical to meet AYAs' social well-being needs.

High-Throughput Drug Screening of Primary Tumor Cells Identifies Therapeutic Strategies for Treating Children with High-Risk Cancer

For one-third of patients with pediatric cancer enrolled in precision medicine programs, molecular profiling does not result in a therapeutic recommendation. To identify potential strategies for treating these high-risk pediatric patients, we performed in vitro screening of 125 patient-derived samples against a library of 126 anticancer drugs. Tumor cell expansion did not influence drug responses, and 82% of the screens on expanded tumor cells were completed while the patients were still under clinical care. High-throughput drug screening (HTS) confirmed known associations between activating genomic alterations in NTRK, BRAF, and ALK and responses to matching targeted drugs. The in vitro results were further validated in patient-derived xenograft models in vivo and were consistent with clinical responses in treated patients. In addition, effective combinations could be predicted by correlating sensitivity profiles between drugs. Furthermore, molecular integration with HTS identified biomarkers of sensitivity to WEE1 and MEK inhibition. Incorporating HTS into precision medicine programs is a powerful tool to accelerate the improved identification of effective biomarker-driven therapeutic strategies for treating high-risk pediatric cancers.

SIGNIFICANCE

Integrating HTS with molecular profiling is a powerful tool for expanding precision medicine to support drug treatment recommendations and broaden the therapeutic options available to high-risk pediatric cancers.

Precision Medicine Is Changing the Roles of Healthcare Professionals, Scientists, and Research Staff: Learnings from a Childhood Cancer Precision Medicine Trial

Precision medicine programs aim to utilize novel technologies to identify personalized treatments for children with cancer. Delivering these programs requires interdisciplinary efforts, yet the many groups involved are understudied. This study explored the experiences of a broad range of professionals delivering Australia's first precision medicine trial for children with poor-prognosis cancer: the PRecISion Medicine for Children with Cancer (PRISM) national clinical trial of the Zero Childhood Cancer Program. We conducted semi-structured interviews with 85 PRISM professionals from eight professional groups, including oncologists, surgeons, clinical research associates, scientists, genetic professionals, pathologists, animal care technicians, and nurses. We analyzed interviews thematically. Professionals shared that precision medicine can add complexity to their role and result in less certain outcomes for families. Although many participants described experiencing a greater emotional impact from their work, most expressed very positive views about the impact of precision medicine on their profession and its future potential. Most reported navigating precision medicine without formal training. Each group described unique challenges involved in adapting to precision medicine in their profession. Addressing training gaps and meeting the specific needs of many professional groups involved in precision medicine will be essential to ensure the successful implementation of standard care.

Memory of stochastic single-cell apoptotic signaling promotes chemoresistance in neuroblastoma

Gene expression noise is known to promote stochastic drug resistance through the elevated expression of individual genes in rare cancer cells. However, we now demonstrate that chemoresistant neuroblastoma cells emerge at a much higher frequency when the influence of noise is integrated across multiple components of an apoptotic signaling network. Using a JNK activity biosensor with longitudinal high-content and in vivo intravital imaging, we identify a population of stochastic, JNK-impaired, chemoresistant cells that exist because of noise within this signaling network. Furthermore, we reveal that the memory of this initially random state is retained following chemotherapy treatment across a series of in vitro, in vivo, and patient models. Using matched PDX models established at diagnosis and relapse from individual patients, we show that HDAC inhibitor priming cannot erase the memory of this resistant state within relapsed neuroblastomas but improves response in the first-line setting by restoring drug-induced JNK activity within the chemoresistant population of treatment-naïve tumors.

Prospective longitudinal evaluation of treatment-related toxicity and health-related quality of life during the first year of treatment for pediatric acute lymphoblastic leukemia

Background

Pediatric acute lymphoblastic leukemia (ALL) therapy is accompanied by treatment-related toxicities (TRTs) and impaired quality of life. In Australia and New Zealand, children with ALL are treated with either Children’s Oncology Group (COG) or international Berlin-Frankfurt-Munster (iBFM) Study Group-based therapy. We conducted a prospective registry study to document symptomatic TRTs (venous thrombosis, neurotoxicity, pancreatitis and bone toxicity), compare TRT outcomes to retrospective TRT data, and measure the impact of TRTs on children’s general and cancer-related health-related quality of life (HRQoL) and parents’ emotional well-being.

Methods

Parents of children with newly diagnosed ALL were invited to participate in the ASSET (Acute Lymphoblastic Leukaemia Subtypes and Side Effects from Treatment) study and a prospective, longitudinal HRQoL study. TRTs were reported prospectively and families completed questionnaires for general (Healthy Utility Index Mark 3) and cancer specific (Pediatric Quality of Life Inventory (PedsQL)-Cancer Module) health related quality of life as well the Emotion Thermometer to assess emotional well-being.

Results

Beginning in 2016, 260 pediatric patients with ALL were enrolled on the TRT registry with a median age at diagnosis of 59 months (range 1–213 months), 144 males (55.4%), majority with Pre-B cell immunophenotype, n = 226 (86.9%), 173 patients (66.5%) treated according to COG platform with relatively equal distribution across risk classification sub-groups. From 2018, 79 families participated in the HRQoL study through the first year of treatment. There were 74 TRT recorded, reflecting a 28.5% risk of developing a TRT. Individual TRT incidence was consistent with previous studies, being 7.7% for symptomatic VTE, 11.9% neurotoxicity, 5.4% bone toxicity and 5.0% pancreatitis. Children’s HRQoL was significantly lower than population norms throughout the first year of treatment. An improvement in general HRQoL, measured by the HUI3, contrasted with the lack of improvement in cancer-related HRQoL measured by the PedsQL Cancer Module over the first 12 months. There were no persisting differences in the HRQoL impact of COG compared to iBFM therapy.

Conclusions

It is feasible to prospectively monitor TRT incidence and longitudinal HRQoL impacts during ALL therapy. Early phases of ALL therapy, regardless of treatment platform, result in prolonged reductions in cancer-related HRQoL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10072-x.

Circulating Tumor DNA in Pediatric Cancer

The measurement of circulating tumor DNA (ctDNA) has gained increasing prominence as a minimally invasive tool for the detection of cancer-specific markers in plasma. In adult cancers, ctDNA detection has shown value for disease-monitoring applications including tumor mutation profiling, risk stratification, relapse prediction, and treatment response evaluation. To date, there are ctDNA tests used as companion diagnostics for adult cancers and it is not understood why the same cannot be said about childhood cancer, despite the marked differences between adult and pediatric oncology. In this review, we discuss the current understanding of ctDNA as a disease monitoring biomarker in the context of pediatric malignancies, including the challenges associated with ctDNA detection in liquid biopsies. The data and conclusions from pediatric cancer studies of ctDNA are summarized, highlighting treatment response, disease monitoring and the detection of subclonal disease as applications of ctDNA. While the data from retrospective studies highlight the potential of ctDNA, large clinical trials are required for ctDNA analysis for routine clinical use in pediatric cancers. We outline the requirements for the standardization of ctDNA detection in pediatric cancers, including sample handling and reproducibility of results. With better understanding of the advantages and limitations of ctDNA and improved detection methods, ctDNA analysis may become the standard of care for patient monitoring in childhood cancers.

Exploring the Metabolic Landscape of AML: From Haematopoietic Stem Cells to Myeloblasts and Leukaemic Stem Cells

Despite intensive chemotherapy regimens, up to 60% of adults with acute myeloid leukaemia (AML) will relapse and eventually succumb to their disease. Recent studies suggest that leukaemic stem cells (LSCs) drive AML relapse by residing in the bone marrow niche and adapting their metabolic profile. Metabolic adaptation and LSC plasticity are novel hallmarks of leukemogenesis that provide important biological processes required for tumour initiation, progression and therapeutic responses. These findings highlight the importance of targeting metabolic pathways in leukaemia biology which might serve as the Achilles' heel for the treatment of AML relapse. In this review, we highlight the metabolic differences between normal haematopoietic cells, bulk AML cells and LSCs. Specifically, we focus on four major metabolic pathways dysregulated in AML; (i) glycolysis; (ii) mitochondrial metabolism; (iii) amino acid metabolism; and (iv) lipid metabolism. We then outline established and emerging drug interventions that exploit metabolic dependencies of leukaemic cells in the treatment of AML. The metabolic signature of AML cells alters during different biological conditions such as chemotherapy and quiescence. Therefore, targeting the metabolic vulnerabilities of these cells might selectively eradicate them and improve the overall survival of patients with AML.

In vitro and in vivo drug screens of tumor cells identify novel therapies for high-risk child cancer

Biomarkers which better match anticancer drugs with cancer driver genes hold the promise of improved clinical responses and cure rates. We developed a precision medicine platform of rapid high-throughput drug screening (HTS) and patient-derived xenografting (PDX) of primary tumor tissue, and evaluated its potential for treatment identification among 56 consecutively enrolled high-risk pediatric cancer patients, compared with conventional molecular genomics and transcriptomics. Drug hits were seen in the majority of HTS and PDX screens, which identified therapeutic options for 10 patients for whom no targetable molecular lesions could be found. Screens also provided orthogonal proof of drug efficacy suggested by molecular analyses and negative results for some molecular findings. We identified treatment options across the whole testing platform for 70% of patients. Only molecular therapeutic recommendations were provided to treating oncologists and led to a change in therapy in 53% of patients, of whom 29% had clinical benefit. These data indicate that in vitro and in vivo drug screening of tumor cells could increase therapeutic options and improve clinical outcomes for high-risk pediatric cancer patients.

Analytical Quality Controls for ddPCR Detection of Minimal Residual Disease in Acute Lymphoblastic Leukemia

Background

Droplet digital PCR (ddPCR) is a promising technique for absolute quantification of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL), but there is no comprehensive quality assurance program to enable its application in clinical laboratories. Current guidelines for real-time quantitative PCR (qPCR) assays targeting immunoglobulin/T-cell receptor (Ig/TCR) gene rearrangements needed adaptation for ddPCR to cover droplet generation, intraassay variation, and interassay variation in the absence of standard curves.

Methods

Six qPCR MRD assays for Ig/TCR gene rearrangements and a standard albumin control gene assay were migrated to a ddPCR platform and used to test 82 remission samples from 6 patients with ALL. Three analytical quality controls (QC) were developed and evaluated for ddPCR MRD detection.

Results

Analytical QC for droplet number generation (DN-QC), for albumin ddPCR assay performance (Alb-QC) and for patient-specific marker assay performance (PS-QC) were established with pass/fail limits and corresponding QC rules. Compared to established qPCRs, the ddPCR assays had comparable sensitivity and quantitative range. Overall, there was close agreement (91%) of MRD results between qPCR and ddPCR (κ = 0.86, P &lt; 0.0001) and stronger concordance in 32 quantifiable samples (R2 = 0.97, P &lt; 0.0001).

Conclusions

The use of this newly developed quality control system for ddPCR MRD testing avoids the need to repeat standard curves and provides reliable results comparable to standardized qPCR methods for MRD detection in ALL.

"We Have All This Knowledge to Give, So Use Us as a Resource": Partnering with Adolescent and Young Adult Cancer Survivors to Determine Consumer-Led Research Priorities

Purpose: Involvement of adolescent and young adult (AYAs) cancer survivors as consumers in research is increasingly encouraged, yet few studies have identified the feasibility and acceptability of methods used to involve them. We aimed to identify: (1) How feasible and acceptable is a consumer-driven, workshop-based research priority-setting approach? And (2) what research priorities do Australian AYA consumers endorse? Methods: AYA cancer survivors diagnosed 15-30 years old and currently younger than 35 years were invited to participate. The AYAs completed a pre-workshop survey to rank their top three priorities from the United Kingdom-based James Lind Alliance list, participated in a 90-minute focus group, and completed a post-workshop evaluation survey. We assessed the workshop feasibility by reviewing considerations, challenges, and enablers of success in the planning and conduct processes. Acceptability was assessed through participants' evaluation surveys and facilitators' informal reflections. The top three priorities were determined from pre-workshop surveys and focus group data. Results: Six survivors participated (M age = 24.2 years, M = 5 years post-treatment, 83% female). All reported that the workshop was an acceptable way to engage with researchers. Costs and recruitment challenges limited the workshop's feasibility. The AYAs' top priority was: What psychological support package improves psychological well-being, social functioning, and mental health during and after treatment? Discussion: The AYA survivors found our workshop to be an acceptable way to engage in research priority-setting. However, the feasibility of this approach depends on the resources available to researchers. Future research is needed to define the optimal method of engagement: What is most acceptable for AYAs and feasible for researchers?

Social Anxiety Symptoms in Survivors of Childhood and Adolescent Cancer

Purpose: Adolescent and young adult (AYA) cancer survivors may be at risk of developing symptoms of social anxiety disorder (SAD) due to disruptions in social participation and functioning following a cancer diagnosis. This study aimed to explore (1) the proportion of Australian AYA-aged survivors of childhood and adolescent cancer who experience symptoms of SAD, (2) how symptoms of SAD are described by survivors as affecting their daily social functioning. Methods: A mixed-methods cross-sectional design was employed, inviting survivors, aged 13-25 years, who had completed treatment between one and ten years ago. Survivors completed a paper-based questionnaire, containing validated measures of SAD, and an optional semistructured interview assessing current social functioning and social anxiety. Results: Twenty-seven survivors aged 13-25 years participated (M = 19.15, 51.9% male, and 7 years post-treatment). Nine (33%) participants reported clinically significant symptoms of SAD. In interviews, survivors reported worries about how others perceived them and fears around meeting new people. Survivors described that this impacted their daily social functioning, leading them to avoid, or endure with distress, feared social situations. Conclusion: This study shows that clinically significant social anxiety may be a concern for a subset of survivors of childhood/adolescent cancer. Identifying which young people are at risk of SAD after cancer and how best to support this vulnerable cohort is critical.

Determinants of social functioning among adolescents and young adults with cancer: A systematic review

OBJECTIVES

Survivors of adolescent and young adult (AYA) cancer report deficits in social functioning relative to healthy peers. Identifying factors related to their social functioning is critical to improve their long-term social outcomes. This review addressed: (1) How is social functioning defined and measured among studies of AYAs who have had cancer? (2) What factors have quantitatively/qualitatively are associated with/predictors of social functioning? and (3) What associated factors/predictors of social functioning are modifiable and amenable to intervention?

METHODS

A systematic review was conducted to identify publications from 2000 to 2021, meeting these criteria: (1) mean/median age at diagnosis/treatment 13-40, (2) assessed social functioning with a validated measure and included factors associated with/predictive of social functioning and/or qualitatively assessed young people's perceptions of factors related to their social functioning and (3) was peer-reviewed/published in English.

RESULTS

Thirty-seven publications were included. Definitions and measures of social functioning varied, and factors related to social functioning varied based on definition. Factors most commonly associated with decreased social functioning included treatment status (receiving or completed treatment), poor physical functioning, depression, negative body image, engaging in social comparisons, social/cultural stigma around cancer, and fatigue. Increased social functioning was most commonly associated with social support and the quality/age-appropriateness of care.

CONCLUSIONS

Social functioning is multidimensional construct for AYAs diagnosed with cancer and may not be adequately assessed with measures of adjustment or quality of life. Future studies should clarify how to optimally define and measure social functioning in this population, to ensure their functioning can be protected and promoted long-term.

Outcomes for Australian children with relapsed/refractory acute lymphoblastic leukaemia treated with blinatumomab

We report on the Australian experience of blinatumomab for treatment of 24 children with relapsed/refractory precursor B-cell acute lymphoblastic leukaemia (B-ALL) and high-risk genetics, resulting in a minimal residual disease (MRD) response rate of 58%, 2-year progression-free survival (PFS) of 39% and 2-year overall survival of 63%. In total, 83% (n = 20/24) proceeded to haematopoietic stem cell transplant, directly after blinatumomab (n = 12) or following additional salvage therapy (n = 8). Four patients successfully received CD19-directed chimeric antigen receptor T-cell therapy despite prior blinatumomab exposure. Inferior 2-year PFS was associated with MRD positivity (20%, n = 15) and in KMT2A-rearranged infants (15%, n = 9). Our findings highlight that not all children with relapsed/refractory B-ALL respond to blinatumomab and factors such as blast genotype may affect prognosis.

Efficacy of MEK inhibition in a recurrent malignant peripheral nerve sheath tumor

The prognosis of recurrent malignant peripheral nerve sheath tumors (MPNST) is dismal, with surgical resection being the only definitive salvage therapy. Treatment with chemoradiation approaches has not significantly improved patient outcomes. Similarly, trials of therapies targeting MPNST genomic drivers have thus far been unsuccessful. Improved understanding of the molecular pathogenesis of MPNST indicates frequent activation of the mitogen-activated protein kinase (MAPK) cell signaling pathway. MEK inhibitors have shown activity in preclinical studies; however, their clinical efficacy has not been reported to date. We describe here a case of sustained complete response to MEK inhibition in an adolescent patient with a recurrent metastatic MPNST with multiple alterations in the MAPK pathway, guided by a precision oncology approach.

Methotrexate-related central neurotoxicity: clinical characteristics, risk factors and genome-wide association study in children treated for acute lymphoblastic leukemia

Symptomatic methotrexate-related central neurotoxicity, 'MTX neurotoxicity', is a severe toxicity experienced during acute lymphoblastic leukemia (ALL) therapy with potential long-term neurologic complications. Risk factors and long-term outcomes require further study. We conducted a systematic, retrospective review of 1251 consecutive Australian children enrolled on BFM or COG-based protocols between 1998-2013. Clinical risk predictors for MTX neurotoxicity were analyzed using regression. A genome-wide association study (GWAS) was performed on 48 cases and 537 controls. The incidence of MTX neurotoxicity was 7.6% (n=95/1251), at a median of 4 months from ALL diagnosis and 8 days after intravenous or intrathecal MTX. Grade 3 elevation of serum aspartate aminotransferase (P=0.005, OR 2.31 (1.28-4.16)) in induction/consolidation was associated with MTX neurotoxicity, after accounting for the only established risk factor, age a10 years. Cumulative incidence of CNS relapse was increased in children where intrathecal MTX was omitted following symptomatic MTX neurotoxicity (n=48) compared to where intrathecal MTX was continued throughout therapy (n=1174) (P=0.047). Five-year CNS relapsefree survival was 89.2%±4.6% when intrathecal MTX was ceased compared to 95.4%±0.6% when intrathecal MTX was continued. Recurrence of MTX neurotoxicity was low (12.9%) for patients whose intrathecal MTX was continued after their first episode. The GWAS identified SNPs associated with MTX neurotoxicity near genes regulating neuronal growth, neuronal differentiation and cytoskeletal organization (P>1E-06). In conclusion, increased serum aspartate aminotransferase and age a10 years at diagnosis were independent risk factors for MTX neurotoxicity. Our data do not support cessation of intrathecal MTX after a first MTX neurotoxicity event.

Targeted Therapy of TERT-Rearranged Neuroblastoma with BET Bromodomain Inhibitor and Proteasome Inhibitor Combination Therapy

PURPOSE

TERT gene rearrangement with transcriptional superenhancers leads to TERT overexpression and neuroblastoma. No targeted therapy is available for clinical trials in patients with TERT-rearranged neuroblastoma.

EXPERIMENTAL DESIGN

Anticancer agents exerting the best synergistic anticancer effects with BET bromodomain inhibitors were identified by screening an FDA-approved oncology drug library. The synergistic effects of the BET bromodomain inhibitor OTX015 and the proteasome inhibitor carfilzomib were examined by immunoblot and flow cytometry analysis. The anticancer efficacy of OTX015 and carfilzomib combination therapy was investigated in mice xenografted with TERT-rearranged neuroblastoma cell lines or patient-derived xenograft (PDX) tumor cells, and the role of TERT reduction in the anticancer efficacy was examined through rescue experiments in mice.

RESULTS

The BET bromodomain protein BRD4 promoted TERT-rearranged neuroblastoma cell proliferation through upregulating TERT expression. Screening of an approved oncology drug library identified the proteasome inhibitor carfilzomib as the agent exerting the best synergistic anticancer effects with BET bromodomain inhibitors including OTX015. OTX015 and carfilzomib synergistically reduced TERT protein expression, induced endoplasmic reticulum stress, and induced TERT-rearranged neuroblastoma cell apoptosis which was blocked by TERT overexpression and endoplasmic reticulum stress antagonists. In mice xenografted with TERT-rearranged neuroblastoma cell lines or PDX tumor cells, OTX015 and carfilzomib synergistically blocked TERT expression, induced tumor cell apoptosis, suppressed tumor progression, and improved mouse survival, which was largely reversed by forced TERT overexpression.

CONCLUSIONS

OTX015 and carfilzomib combination therapy is likely to be translated into the first clinical trial of a targeted therapy in patients with TERT-rearranged neuroblastoma.

DIPG-75. PRECISION MEDICINE FOR PAEDIATRIC HIGH-GRADE DIFFUSE MIDLINE GLIOMAS - RESULTS FROM THE ZERO CHILDHOOD CANCER COMPREHENSIVE PRECISION MEDICINE PROGRAM

The Australian Zero Childhood Cancer (ZERO) program aims to assess the feasibility of a comprehensive precision medicine approach to improve outcomes for patients with an expected survival &lt;30%. ZERO combines molecular profiling (whole genome sequencing, whole transcriptome sequencing, DNA methylation profiling) with in vitro high-throughput drug screening (HTS) and patient-derived xenograft drug efficacy testing. We report on the cohort of patients with midline high-grade glioma (HGG), including H3-K27M DMG, enrolled on the pilot study (TARGET) and on the ongoing ZERO clinical trial (PRISM). We identified 48 patients with midline HGG. Fresh or cryopreserved samples were submitted in 37 cases and cell culture was attempted in 30/37 cases with 45% success rate. The most commonly mutated genes/pathways identified by molecular profiling include H3-K27M mutations, DNA repair pathway, and PI3K/mTOR pathway. Two targetable fusions (NTRK and FGFR1) were reported. Five patients with germline alterations were identified. Thirty-five (72%) patients received a therapeutic recommendation from the ZERO molecular tumour board and the main recommended therapies were mTOR inhibitors, PARP inhibitors or tyrosine kinase inhibitors. HTS added evidence for the recommended therapy (n=3) or identified novel potential therapy (n=1). Out of the 35 patients, 16 received a recommended drug. Response to treatment was complete response for five months (n=1), partial response for nine months (n=1), stable disease (n=4), and progressive disease (n=10). These results highlight the feasibility of the ZERO platform and the value of fresh biopsy, necessary for pre-clinical drug testing. Targetable alterations were identified leading to clinical benefit in six patients.

Mouse models of high-risk neuroblastoma

Informative and realistic mouse models of high-risk neuroblastoma are central to understanding mechanisms of tumour initiation, progression, and metastasis. They also play vital roles in validating tumour drivers and drug targets, as platforms for assessment of new therapies and in the generation of drug sensitivity data that can inform treatment decisions for individual patients. This review will describe genetically engineered mouse models of specific subsets of high-risk neuroblastoma, the development of patient-derived xenograft models that more broadly represent the diversity and heterogeneity of the disease, and models of primary and metastatic disease. We discuss the research applications, advantages, and limitations of each model type, the importance of model repositories and data standards for supporting reproducible, high-quality research, and potential future directions for neuroblastoma mouse models.

Whole genome, transcriptome and methylome profiling enhances actionable target discovery in high-risk pediatric cancer

The Zero Childhood Cancer Program is a precision medicine program to benefit children with poor-outcome, rare, relapsed or refractory cancer. Using tumor and germline whole genome sequencing (WGS) and RNA sequencing (RNAseq) across 252 tumors from high-risk pediatric patients with cancer, we identified 968 reportable molecular aberrations (39.9% in WGS and RNAseq, 35.1% in WGS only and 25.0% in RNAseq only). Of these patients, 93.7% had at least one germline or somatic aberration, 71.4% had therapeutic targets and 5.2% had a change in diagnosis. WGS identified pathogenic cancer-predisposing variants in 16.2% of patients. In 76 central nervous system tumors, methylome analysis confirmed diagnosis in 71.1% of patients and contributed to a change of diagnosis in two patients (2.6%). To date, 43 patients have received a recommended therapy, 38 of whom could be evaluated, with 31% showing objective evidence of clinical benefit. Comprehensive molecular profiling resolved the molecular basis of virtually all high-risk cancers, leading to clinical benefit in some patients.

CD30 and ALK combination therapy has high therapeutic potency in RANBP2-ALK-rearranged epithelioid inflammatory myofibroblastic sarcoma

BACKGROUND

Epithelioid inflammatory myofibroblastic sarcoma (eIMS) is characterised by perinuclear ALK localisation, CD30 expression and early relapse despite crizotinib treatment. We aimed to identify therapies to prevent and/or treat ALK inhibitor resistance.

METHODS

Malignant ascites, from an eIMS patient at diagnosis and following multiple relapses, were used to generate matched diagnosis and relapse xenografts.

RESULTS

Xenografts were validated by confirmation of RANBP2-ALK rearrangement, perinuclear ALK localisation and CD30 expression. Although brentuximab-vedotin (BV) demonstrated single-agent activity, tumours regrew during BV therapy. BV resistance was associated with reduced CD30 expression and induction of ABCB1. BV resistance was reversed in vitro by tariquidar, but combination BV and tariquidar treatment only briefly slowed xenograft growth compared with BV alone. Combining BV with either crizotinib or ceritinib resulted in marked tumour shrinkage in both xenograft models, and resulted in prolonged tumour-free survival in the diagnosis compared with the relapse xenograft.

CONCLUSIONS

CD30 is a therapeutic target in eIMS. BV efficacy is limited by the rapid emergence of resistance. Prolonged survival with combination ALK and CD30-targeted-therapy in the diagnosis model provides the rationale to trial this combination in eIMS patients at diagnosis. This combination could also be considered for other CD30-positive, ALK-rearranged malignancies.

An HPLC–PDA method for determination of alectinib concentrations in the plasma of an adolescent

Alectinib is a central nervous system-active small molecule anaplastic lymphoma kinase (ALK) inhibitor that is effective in the treatment of patients with ALK positive tumors, including advanced non-small cell lung cancers and lymphomas. A simple, isocratic high-performance liquid chromatography–photo diode array detection (HPLC–PDA) assay for measurement of alectinib in human plasma is described. Alectinib is extracted from the plasma matrix by addition of methanol, followed by centrifugation and acidification with 0.1% formic acid. It elutes with a run time of 4.6 min using a 250 mm × 4.6 mm RP-C18 column with 0.1% aqueous formic acid and methanol (35:65, v/v) and a flow rate of 1 mL/min. Detection was at 339 nm. Linear calibration plots were achieved in the range of 0.1–20 μg/mL for alectinib (r2 = 0.9996). With limits of detection and quantification of 0.05 and 0.1 μg/mL, respectively, and excellent precision (%CV < 10%), accuracy (bias < ±12%), and recovery (>97%) within the 1–20 μg/mL concentration range, this assay was suitable for measuring pre-dose alectinib concentrations in an adolescent receiving 600-mg doses twice daily.

Genome-Wide Association Meta-Analysis of Single-Nucleotide Polymorphisms and Symptomatic Venous Thromboembolism during Therapy for Acute Lymphoblastic Leukemia and Lymphoma in Caucasian Children

Symptomatic venous thromboembolism (VTE) occurs in five percent of children treated for acute lymphoblastic leukemia (ALL), but whether a genetic predisposition exists across different ALL treatment regimens has not been well studied.

METHODS

We undertook a genome-wide association study (GWAS) meta-analysis for VTE in consecutively treated children in the Nordic/Baltic acute lymphoblastic leukemia 2008 (ALL2008) cohort and the Australian Evaluation of Risk of ALL Treatment-Related Side-Effects (ERASE) cohort. A total of 92 cases and 1481 controls of European ancestry were included.

RESULTS

No SNPs reached genome-wide significance (p < 5 × 10-8) in either cohort. Among the top 34 single-nucleotide polymorphisms (SNPs) (p < 1 × 10-6), two loci had concordant effects in both cohorts: ALOX15B (rs1804772) (MAF: 1%; p = 3.95 × 10-7) that influences arachidonic acid metabolism and thus platelet aggregation, and KALRN (rs570684) (MAF: 1%; p = 4.34 × 10-7) that has been previously associated with risk of ischemic stroke, atherosclerosis, and early-onset coronary artery disease.

CONCLUSION

This represents the largest GWAS meta-analysis conducted to date associating SNPs to VTE in children and adolescents treated on childhood ALL protocols. Validation of these findings is needed and may then lead to patient stratification for VTE preventive interventions. As VTE hemostasis involves multiple pathways, a more powerful GWAS is needed to detect combination of variants associated with VTE.

Inhibition of polyamine synthesis and uptake reduces tumor progression and prolongs survival in mouse models of neuroblastoma

Amplification of the MYCN oncogene is associated with an aggressive phenotype and poor outcome in childhood neuroblastoma. Polyamines are highly regulated essential cations that are frequently elevated in cancer cells, and the rate-limiting enzyme in polyamine synthesis, ornithine decarboxylase 1 (ODC1), is a direct transcriptional target of MYCN. Treatment of neuroblastoma cells with the ODC1 inhibitor difluoromethylornithine (DFMO), although a promising therapeutic strategy, is only partially effective at impeding neuroblastoma cell growth due to activation of compensatory mechanisms resulting in increased polyamine uptake from the surrounding microenvironment. In this study, we identified solute carrier family 3 member 2 (SLC3A2) as the key transporter involved in polyamine uptake in neuroblastoma. Knockdown of SLC3A2 in neuroblastoma cells reduced the uptake of the radiolabeled polyamine spermidine, and DFMO treatment increased SLC3A2 protein. In addition, MYCN directly increased polyamine synthesis and promoted neuroblastoma cell proliferation by regulating SLC3A2 and other regulatory components of the polyamine pathway. Inhibiting polyamine uptake with the small-molecule drug AMXT 1501, in combination with DFMO, prevented or delayed tumor development in neuroblastoma-prone mice and extended survival in rodent models of established tumors. Our findings suggest that combining AMXT 1501 and DFMO with standard chemotherapy might be an effective strategy for treating neuroblastoma.

Enrichment of atypical hyperdiploidy and IKZF1 deletions detected by SNP-microarray in high-risk Australian AIEOP-BFM B-cell acute lymphoblastic leukaemia cohort

Acute lymphoblastic leukaemia (ALL) is the most common childhood malignancy with the majority of patients being classified as B-cell lineage (B-ALL). The sub-classification of B-ALL is based on genomic architecture. Recent studies have demonstrated the capability of SNP-microarrays to detect genomic changes in B-ALL which cannot be observed by conventional cytogenetic methods. In current clinical trials, B-ALL patients at high risk of relapse are mainly identified by adverse cancer genomics and/or poor response to early therapy. To test the hypothesis that inclusion of SNP-microarrays in frontline diagnostics could more efficiently and accurately identify adverse genomic factors than conventional techniques, we evaluated the Australian high-risk B-ALL cohort enrolled on AIEOP-BFM ALL 2009 study (n = 33). SNP-microarray analysis identified additional aberrations in 97% of patients (32/33) compared to conventional techniques. This changed the genomic risk category of 24% (8/33) of patients. Additionally, 27% (9/33) of patients exhibited a 'hyperdiploid' genome, which is generally associated with a good genomic risk and favourable outcomes. An enrichment of IKZF1 deletions was observed with one third of the cohort affected. Our findings suggest the current classification system could be improved and highlights the need to use more sensitive techniques such as SNP-microarray for cytogenomic risk stratification in B-ALL.

Abstract 4741: Re-evaluating the role of P-glycoprotein in the resistance of high-risk neuroblastoma to standard-of-care chemotherapies

Background: Neuroblastoma is the most common extracranial solid malignancy in children, comprising 15% of cancer related deaths. Despite intensive treatment, patients with high-risk neuroblastoma (HR-NB) have a survival rate of ~50%, largely due to intrinsic or acquired drug resistance. The multidrug transporter P-glycoprotein (P-gp; ABCB1) effluxes several conventional agents used in HR-NB induction therapy, including doxorubicin, vincristine and etoposide, as well as the ALK inhibitor crizotinib. We observed high P-gp expression in HR-NB cell lines and patient-derived xenograft (PDX) models, so sought to assess the prevalence of P-gp expression and its role in resistance to standard-of-care chemotherapies and relevant targeted agents.

Methods and Results: Using RNA-sequencing, immunohistochemistry and western blot on panels of neuroblastoma tumour samples, PDX models and cell lines, we demonstrated that high ABCB1/P-gp expression is frequent in HR-NB. Analysis of ABCB1 levels in large patient tumor datasets suggests that high expression is attributable to the sympathoadrenal lineage of the disease, that high expression is more common in HR-NB than in most other cancers, and that high relative expression of ABCB1 in HR-NB tumours is associated with poorer outcome, consistent with its multidrug transporter function. We demonstrated that the P-gp inhibitor tariquidar and P-gp knockdown (shRNA) both strongly sensitize cultured high P-gp expressing neuroblastoma cells to vincristine, doxorubicin and etoposide but not to ALK inhibitors. Further, P-gp knockdown sensitized human neuroblastoma xenografts to vincristine, substantially extending survival.

Conclusions: Elevated P-gp expression is common in HR-NB and can be sufficient to confer resistance to standard-of-care chemotherapies in model systems. Our findings suggest that tumour P-gp levels might be used to guide treatment options for individual patients, and to avoid ineffective treatments. The potential of P-gp inhibitors as adjuncts to conventional chemotherapy for HR-NB should be further investigated.

Citation Format: Caroline Atkinson, Carole M. Tactacan, Alvin Kamili, Federica Saletta, Christine Gana, Georgina L. Eden, Chelsea Mayoh, Richard B. Lock, Murray D. Norris, Michelle Haber, Andrew J. Gifford, Toby N. Trahair, Jamie I. Fletcher. Re-evaluating the role of P-glycoprotein in the resistance of high-risk neuroblastoma to standard-of-care chemotherapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4741.

Abstract 4824: Targeting CD30 as a novel treatment strategy in RANBP2-ALK-rearranged inflammatory myofibroblastic tumor

Rationale: Inflammatory myofibroblastic tumors (IMTs) are a particularly rare type of soft tissue sarcoma comprised of myofibroblastic spindle cells and an accompanying inflammatory infiltrate. There is an unmet clinical need for effective treatment regimens for patients diagnosed with IMT with anaplastic lymphoma kinase (ALK) rearrangement, who relapse following ALK inhibitor (ALKi) therapy or who present with aggressive disease. Fusion of RAN Binding Protein 2 (RANBP2) with ALK in IMT is associated with aggressive disease and has been correlated with tumor cell expression of CD30. This study investigated CD30 as a potential therapeutic target in IMT and the efficacy of the CD30-targeted antibody-monomethyl auristatin E conjugate, Brentuximab Vedotin (BV).

Methods and Results: In a cohort of five recent IMT patients at the Sydney Children’s Hospital, RANBP2-ALK fusion was identified in three patients (IMT1, IMT2 and IMT3) by RNA capture sequencing, while patients IMT4 and IMT5 (who did not relapse) harbored CLTC-ALK or SEC31A-ALK fusions respectively. Expression of CD30 was confirmed two of three RANBP2-ALK fusion positive tumors by immunohistochemistry. We established cell cultures and xenografts from malignant ascites of IMT1, at diagnosis (IMT1A) and at relapse (IMT1D) after treatment with ALKi’s and low dose chemotherapy. CD30 expression was retained in the cell cultures and xenograft tumors, as demonstrated by flow cytometry and tumor histology. BV was investigated as a potential treatment for IMT with RANBP2-ALK fusion. BV reduced IMT1A and IMT1D cell viability in vitro in resazurin cell viability assays. IMT1A and IMT1D xenograft mice had a partial response to BV which significantly (p&lt;0.0001) prolonged survival compared to untreated controls. However, tumors eventually recurred. Resistance to BV correlated with upregulation of P-glycoprotein and reduced CD30 antigen expression in cells from treated IMT xenograft tumors. The combination of the ALK inhibitor crizotinib with BV has also been investigated. In vivo, the combination of crizotinib and BV resulted in complete resolution of tumor and significantly (p&lt;0.0001) improved survival compared to the individual agents.

Conclusion: CD30 is a promising therapeutic target in RANBP2-ALK-rearranged IMT. BV successfully reduced IMT cell viability in vitro and prolonged survival in IMT xenografted mice, both as a single agent and when given in combination with crizotinib. Since BV is current clinical use for the treatment of Hodgkin lymphoma it may be possible to rapidly translate these findings into clinical practice for the treatment of IMT.

Citation Format: Ashleigh M. Fordham, James Blackburn, Erin E. Heyer, Jinhan Xie, Emily V. Mould, Andrew J. Gifford, Lisa T. Morgan, Carol Wadham, Mitali Fadia, Jamie I. Fletcher, Karen L. MacKenzie, Toby N. Trahair. Targeting CD30 as a novel treatment strategy in RANBP2-ALK-rearranged inflammatory myofibroblastic tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4824.

Abstract 2884: Establishment of patient-derived xenograft models for high-risk neuroblastoma

Background: High-risk neuroblastoma (HR-NB) accounts for 15% of all pediatric oncology deaths, with long-term survival approximately 50%. Predictive preclinical models play an important role in the assessment of new treatment strategies and as avatar models for personalized medicine. We investigated the feasibility of establishing patient-derived xenograft (PDX) models of HR-NB from a range of tumor-bearing patient materials at diagnosis and relapse, and assessed techniques that may improve engraftment times and success rates.

Methods and Results: Tumor materials were obtained from 12 HR-NB patients, including primary and metastatic solid tumor biopsies, bone marrow mononuclear cells, pleural fluid and residual cells from cytogenetic analysis. Samples were processed and implanted subcutaneously into immunocompromised mice. The engraftment success rates were 33% (4/12) for diagnosis samples and 100% (6/6) for relapse samples. Median engraftment time to 1000mm3 tumor was 93.5 days (range 33–210 days). Engraftment at diagnosis was associated with poor outcome. PDX models were validated against primary material by histology, short-tandem repeat analysis, and single nucleotide polymorphism (SNP) array. PDXs matched the donor patient specimen in all but one case, where attempted engraftment from pleural fluid resulted in EBV-associated lymphoid proliferation. Attempted engraftment of tumor derived from a lymph node metastasis was associated with human T-lymphocyte infiltration of the mouse liver and spleen. Matched PDX models established directly from tumor biopsy and via short-term cytogenetics culture were equally similar to the donor tumor by SNP array and histological analysis. We directly compared engraftment rates for three different patient tumors at subcutaneous, intramuscular and orthotopic implantation sites. For two patient tumors, orthotopic engraftment was significantly faster than other sites, while the third model is ongoing.

Conclusion: HR-NB PDX models can be established from diverse sample types, allowing us to develop a preclinical testing platform for new therapies and the capacity to model personalized therapy. Engraftment of relapse samples can be readily achieved, while engraftment at diagnosis may portend poor prognosis. The engraftment time of neuroblastoma patient samples might be accelerated by orthotopic implantation.

Citation Format: Alvin Kamili, Andrew J. Gifford, Nancy Li, Chelsea Mayoh, Georgina L. Eden, Jinhan Xie, Robyn E. Lukeis, Murray D. Norris, Michelle Haber, Geoffrey McCowage, Toby N. Trahair, Jamie I. Fletcher. Establishment of patient-derived xenograft models for high-risk neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2884.

Enrolment in paediatric oncology early-phase clinical trials: The health-care professionals' perspective

AIM

Approximately 20-30% of children/adolescents with cancer will not respond to standard therapies. These children are usually offered experimental treatment in the form of an early-phase clinical trial. We examined the perspectives of health-care professionals (HCPs) regarding obtaining informed consent for early-phase trials in paediatric oncology.

METHODS

We collected survey data from 87 HCPs working in paediatric cancer centres across Australia and New Zealand.

RESULTS

HCPs were, on average, 44 years old (range = 25-74), with 15.8 years' experience in paediatric oncology (range = 1-40). Few HCPs (17.4%) received training for early-phase trial consent; however, most were willing to attend training (77.9%). HCPs (61.6%) reported that they informed families about early-phase trials without any attempt to influence their decision. However, 23.3% of HCPs reported that they informed families that their child would benefit. HCPs' main obstacle in obtaining consent was their perception of parents' eagerness to 'try anything' (52.3%). HCPs perceived that many parents misunderstood key clinical trials concepts, with 25.2% of HCPs believing that not being given clear information influenced parents' decisions. Physicians were more likely than social workers/nurses to inform families that other children will benefit from enrolment in the study. Social workers/nurses appeared to rate the chance of benefits for the patient higher than physicians.

CONCLUSIONS

HCPs may experience difficulty conducting early-phase trial consultations and obtaining valid informed consent. Our study highlights the need for formal training for HCPs and additional patient education tools.

Alectinib is effective, safe and tolerable in an adolescent with stage IVB ALK-rearranged adenocarcinoma of the lung

Anaplastic lymphoma kinase (ALK) inhibitors such as crizotinib and alectinib have been shown to have significant activity in ALK-rearranged non-small cell lung cancers (NSCLC). There are no data for alectinib's safety or efficacy in younger patients, though it is superior to crizotinib in adult trials. We present a 14-year old girl diagnosed with stage IV-B ALK-positive adenocarcinoma of the lung after presenting with cough and fever. She was commenced on alectinib at adult dose and has had sustained complete metabolic remission for 9 months. She is the youngest patient with lung adenocarcinoma to be treated with alectinib.

Too many targets, not enough patients: rethinking neuroblastoma clinical trials

Neuroblastoma is a rare solid tumour of infancy and early childhood with a disproportionate contribution to paediatric cancer mortality and morbidity. Combination chemotherapy, radiation therapy and immunotherapy remains the standard approach to treat high-risk disease, with few recurrent, actionable genetic aberrations identified at diagnosis. However, recent studies indicate that actionable aberrations are far more common in relapsed neuroblastoma, possibly as a result of clonal expansion. In addition, although the major validated disease driver, MYCN, is not currently directly targetable, multiple promising approaches to target MYCN indirectly are in development. We propose that clinical trial design needs to be rethought in order to meet the challenge of providing rigorous, evidence-based assessment of these new approaches within a fairly small patient population and that experimental therapies need to be assessed at diagnosis in very-high-risk patients rather than in relapsed and refractory patients.

Targeted Next-Generation Sequencing for Detecting MLL Gene Fusions in Leukemia

Mixed lineage leukemia (MLL) gene rearrangements characterize approximately 70% of infant and 10% of adult and therapy-related leukemia. Conventional clinical diagnostics, including cytogenetics and fluorescence in situ hybridization (FISH) fail to detect MLL translocation partner genes (TPG) in many patients. Long-distance inverse (LDI)-PCR, the "gold standard" technique that is used to characterize MLL breakpoints, is laborious and requires a large input of genomic DNA (gDNA). To overcome the limitations of current techniques, a targeted next-generation sequencing (NGS) approach that requires low RNA input was tested. Anchored multiplex PCR-based enrichment (AMP-E) was used to rapidly identify a broad range of MLL fusions in patient specimens. Libraries generated using Archer FusionPlex Heme and Myeloid panels were sequenced using the Illumina platform. Diagnostic specimens (n = 39) from pediatric leukemia patients were tested with AMP-E and validated by LDI-PCR. In concordance with LDI-PCR, the AMP-E method successfully identified TPGs without prior knowledge. AMP-E identified 10 different MLL fusions in the 39 samples. Only two specimens were discordant; AMP-E successfully identified a MLL-MLLT1 fusion where LDI-PCR had failed to determine the breakpoint, whereas a MLL-MLLT3 fusion was not detected by AMP-E due to low expression of the fusion transcript. Sensitivity assays demonstrated that AMP-E can detect MLL-AFF1 in MV4-11 cell dilutions of 10^-7 and transcripts down to 0.005 copies/ng.Implications: This study demonstrates a NGS methodology with improved sensitivity compared with current diagnostic methods for MLL-rearranged leukemia. Furthermore, this assay rapidly and reliably identifies MLL partner genes and patient-specific fusion sequences that could be used for monitoring minimal residual disease. Mol Cancer Res; 16(2); 279-85. ©2017 AACR.

MultiDimensional ClinOmics for Precision Therapy of Children and Adolescent Young Adults with Relapsed and Refractory Cancer: A Report from the Center for Cancer Research

PURPOSE

We undertook a multidimensional clinical genomics study of children and adolescent young adults with relapsed and refractory cancers to determine the feasibility of genome-guided precision therapy.

EXPERIMENTAL DESIGN

Patients with non-central nervous system solid tumors underwent a combination of whole exome sequencing (WES), whole transcriptome sequencing (WTS), and high-density single-nucleotide polymorphism array analysis of the tumor, with WES of matched germline DNA. Clinically actionable alterations were identified as a reportable germline mutation, a diagnosis change, or a somatic event (including a single nucleotide variant, an indel, an amplification, a deletion, or a fusion gene), which could be targeted with drugs in existing clinical trials or with FDA-approved drugs.

RESULTS

Fifty-nine patients in 20 diagnostic categories were enrolled from 2010 to 2014. Ages ranged from 7 months to 25 years old. Seventy-three percent of the patients had prior chemotherapy, and the tumors from these patients with relapsed or refractory cancers had a higher mutational burden than that reported in the literature. Thirty patients (51% of total) had clinically actionable mutations, of which 24 (41%) had a mutation that was currently targetable in a clinical trial setting, 4 patients (7%) had a change in diagnosis, and 7 patients (12%) had a reportable germline mutation.

CONCLUSIONS

We found a remarkably high number of clinically actionable mutations in 51% of the patients, and 12% with significant germline mutations. We demonstrated the clinical feasibility of next-generation sequencing in a diverse population of relapsed and refractory pediatric solid tumors. Clin Cancer Res; 22(15); 3810-20. ©2016 AACR.

Identification of plasma complement C3 as a potential biomarker for neuroblastoma using a quantitative proteomic approach

The majority of patients diagnosed with neuroblastoma present with aggressive disease. Improved detection of neuroblastoma cancer cells following initial therapy may help in stratifying patient outcome and monitoring for relapse. To identify potential plasma biomarkers, we utilised a liquid chromatography-tandem mass spectrometry-based proteomics approach to detect differentially-expressed proteins in serum from TH-MYCN mice. TH-MYCN mice carry multiple copies of the human MYCN oncogene in the germline and homozygous mice for the transgene develop neuroblastoma in a manner resembling the human disease. The abundance of plasma proteins was measured over the course of disease initiation and progression. A list of 86 candidate plasma biomarkers was generated. Pathway analysis identified significant association of these proteins with genes involved in the complement system. One candidate, complement C3 protein, was significantly enriched in the plasma of TH-MYCN(+/+) mice at both 4 and 6weeks of age, and was found to be elevated in a cohort of human neuroblastoma plasma samples, compared to healthy subjects. In conclusion, we have demonstrated the suitability of the TH-MYCN(+/+) mouse model of neuroblastoma for identification of novel disease biomarkers in humans, and have identified Complement C3 as a candidate plasma biomarker for measuring disease state in neuroblastoma patients.

BIOLOGICAL SIGNIFICANCE

This study has utilised a unique murine model which develops neuroblastoma tumours that are biologically indistinguishable from human neuroblastoma. This animal model has effectively allowed the identification of plasma proteins which may serve as potential biomarkers of neuroblastoma. Furthermore, the label-free ion count quantitation technique which was used displays significant benefits as it is less labour intensive, feasible and accurate. We have been able to successfully validate this approach by confirming the differential abundance of two different plasma proteins. In addition, we have been able to confirm that the candidate biomarker Complement C3, is more abundant in the plasma of human neuroblastoma patient plasma samples when compared to healthy counterparts. Overall we have demonstrated that this approach can be potentially useful in the identification of biomarker candidates, and that further validation of the candidates may lead to the discovery of novel, clinically useful diagnostic tools in the detection of sub-clinical neuroblastoma.

Transplant-related mortality following allogeneic hematopoeitic stem cell transplantation for pediatric acute lymphoblastic leukemia: 25-year retrospective review

BACKGROUND

Over the last 25 years, donor source, conditioning, graft-versus-host disease prevention and supportive care for children undergoing hematopoeitic stem cell transplantation (HSCT) have changed dramatically. HSCT indications for acute lymphoblastic leukemia (ALL) now include high-risk patients in first and subsequent remission. There is a large burden of infectious and pre-HSCT morbidities, due to myelosuppressive therapy required for remission induction. We hypothesized that, despite these trends, overall survival (OS) had increased.

PROCEDURE

A retrospective audit of allogeneic pediatric HSCT for ALL was performed in our institution over 25 years. Outcomes for 136 HSCTs were analyzed in three consecutive 8-year periods (Period 1: 1/1/1984-31/8/1992, Period 2: 1/9/1992-30/4/2001, Period 3: 1/5/2001-31/12/2009).

RESULTS

Despite a significant increase in unrelated donor HSCT, event-free and OS over 25 years improved significantly. (EFS 31.6-64.8%, P = 0.0027; OS 41.8-78.9%, P < 0.0001) Concurrently, TRM dropped from 33% to 5% (P = 0.0004) whilst relapse rate was static (P = 0.07). TRM reduced significantly for matched sibling and unrelated cord blood transplantation (UCT) in Period 3 compared with earlier periods (P = 0.036, P = 0.0098, respectively). Factors leading to improved survival in patients undergoing UCT include better matching, higher total nucleated cell doses, and significantly faster neutrophil engraftment. Length of initial HSCT admission was similar over time.

CONCLUSION

EFS and OS have increased significantly despite heightened HSCT complexity. This survival gain was due to TRM reduction. Contemporary patients have benefited from refined donor selection and improved supportive care. Overall rates of leukemic relapse post-HSCT are unchanged, and remain the focus for improvement.

FBXW7 regulates glucocorticoid response in T-cell acute lymphoblastic leukaemia by targeting the glucocorticoid receptor for degradation

Loss of function mutation in FBXW7, an E3 ubiquitin ligase, is associated with good prognosis and early glucocorticoid treatment response in childhood T-cell acute lymphoblastic leukemia (T-ALL) by unknown mechanisms. Here, we show that FBXW7 targets the glucocorticoid receptor α (GRα) for ubiquitylation and proteasomal degradation in a manner dependent on glycogen synthase kinase 3 β-mediated phsophorylation. FBXW7 inactivation caused elevated GRα levels, and enhanced the transcriptional response to glucocorticoids. There was significant enhancement of GR transcriptional responses in FBXW7-deficient cell lines and primary T-ALL samples, in particular, for those pro-apoptotic regulatory proteins, BIM and PUMA. Reduced FBXW7 expression or function promoted glucocorticoid sensitivity, but not sensitivity to other chemotherapeutic agents used in T-ALL. Moreover, this was a general feature of different cancer cell types. Taken together, our work defines GRα as a novel FBXW7 substrate and demonstrates that favorable patient prognosis in T-ALL is associated with FBXW7 mutations due to enhanced GRα levels and steroid sensitivity. These findings suggest that inactivation of FBXW7, a putative tumor suppressor protein, may create a synthetic lethal state in the presence of specific anticancer therapies.

Glucocorticoid resistance in paediatric acute lymphoblastic leukaemia

Glucocorticoids (GCs), such as prednisolone and dexamethasone, are key components in multi-agent chemotherapy protocols used for the treatment of acute lymphoblastic leukaemia (ALL). Approximately 10% of children with ALL will respond poorly to GCs, and GC resistance is associated with a significantly inferior outcome. This review summarises the current knowledge of GC resistance in ALL, including the roles of the GC receptor and its co-chaperone molecules, the pro-apoptotic and pro-survival B-cell lymphoma 2 family members and alternative non-apoptotic mechanisms of cell death. It concludes with a discussion on therapeutic attempts to overcome GC resistance.

Evaluation of the NOD/SCID xenograft model for glucocorticoid-regulated gene expression in childhood B-cell precursor acute lymphoblastic leukemia

Background

Glucocorticoids such as prednisolone and dexamethasone are critical drugs used in multi-agent chemotherapy protocols used to treat acute lymphoblastic leukemia (ALL), and response to glucocorticoids is highly predictive of outcome. The NOD/SCID xenograft mouse model of ALL is a clinically relevant model in which the mice develop a systemic leukemia which retains the fundamental biological characteristics of the original disease. Here we report a study evaluating the NOD/SCID xenograft mouse model to investigate glucocorticoid-induced gene expression. Cells from a glucocorticoid-sensitive xenograft derived from a child with B-cell precursor ALL were inoculated into NOD/SCID mice. When highly engrafted the mice were randomized into groups of 4 to receive dexamethasone 15 mg/kg by intraperitoneal injection or vehicle control. Leukemia cells were harvested from mice spleens at 0, 8, 24 or 48 hours thereafter, and gene expression analyzed on Illumina WG-6_V3 chips, comparing all groups to time 0 hours.

Results

The 8 hour dexamethasone-treated timepoint had the highest number of significantly differentially expressed genes, with fewer observed at the 24 and 48 hour timepoints, and with minimal changes seen across the time-matched controls. When compared to publicly available datasets of glucocorticoid-induced gene expression from an in vitro cell line study and from an in vivo study of patients with ALL, at the level of pathways, expression changes in the 8 hour xenograft samples showed a similar response to patients treated with glucocorticoids. Replicate analysis revealed that at the 8 hour timepoint, a dataset with high signal and differential expression, using data from 3 replicates instead of 4 resulted in excellent recovery scores of > 0.9. However at other timepoints with less signal very poor recovery scores were obtained with 3 replicates.

Conclusions

The NOD/SCID xenograft mouse model provides a reproducible experimental system in which to investigate clinically-relevant mechanisms of drug-induced gene regulation in ALL; the 8 hour timepoint provides the highest number of significantly differentially expressed genes; time-matched controls are redundant and excellent recovery scores can be obtained with 3 replicates.

Rituximab for lymphoproliferative disease prior to haematopoietic stem cell transplantation for X-linked severe combined immunodeficiency

Lymphoproliferative disease (LPD) is a complication of congenital and acquired immunodeficiency states. There are a number of treatment options for LPD arising after haematopoietic stem cell or solid organ transplantation including reduction of immunosuppression, targeted therapies, such as the anti-CD20 monoclonal antibody, rituximab, and EBV specific cytotoxic lymphocytes. Treatment of LPD in children with congenital immunodeficiency syndromes remains unsatisfactory and is associated with a high mortality rate. We recently managed an infant found to have polymorphic LPD concurrent with X-linked severe combined immunodeficiency (SCID). Haematopoietic stem cell transplantation (HSCT) had to be deferred because of progressive LPD. Treatment with rituximab resulted in regression of the LPD following which the patient received a 5/6 HLA matched umbilical cord blood (UCB) transplant. The patient remains well 20 months following transplantation. Rituximab treatment may have a useful role in the control of LPD associated with congenital immunodeficiency prior to HSCT.

Long-term outcomes in children with high-risk neuroblastoma treated with autologous stem cell transplantation

We retrospectively analysed the outcomes of children transplanted for high-risk neuroblastoma (NB) at a single institution predominantly transplanted with total body irradiation and chemotherapy. The aims of this study were to determine the prognostic impact of clinical and biological features and to document long-term health outcomes. Forty patients were transplanted with a single unpurged autograft. Fourteen patients died from disease progression and two from late complications of treatment. Twenty-three patients are alive at a median of 4.6 years from diagnosis. Kaplan-Meier estimates of overall survival at 2, 5 and 10 years are 76+/-7.0, 60.2+/-8.4 and 54.7+/-9.3% following transplant. Response to induction therapy was significantly associated with survival (P<0.01). Long-term complications included growth (100%) and pubertal failure (83%), hearing impairment (73%), orthopaedic complications (63%), renal impairment (47%) and thyroid abnormalities (36%). Intrinsic and acquired resistance to chemotherapy remains the major obstacle to improving outcomes in high-risk NB. Although patients with chemo-sensitive disease are less likely to experience a relapse, substantial therapy-related toxicities result in poor long-term health outcomes for survivors.

Adeno-associated virus and lentivirus vectors mediate efficient and sustained transduction of cultured mouse and human dorsal root ganglia sensory neurons

Peripheral nervous system (PNS) sensory neurons are directly involved in the pathophysiology of numerous inherited and acquired neurological conditions. Therefore, efficient and stable gene delivery to these postmitotic cells has significant therapeutic potential. Among contemporary vector systems capable of neuronal transduction, only those based on herpes simplex virus have been extensively evaluated in PNS neurons. We therefore investigated the transduction performance of recombinant adeno-associated virus type 2 (AAV) and VSV-G-pseudotyped lentivirus vectors derived from human immunodeficiency virus (HIV-1) in newborn mouse and fetal human dorsal root ganglia (DRG) sensory neurons. In dissociated mouse DRG cultures both vectors achieved efficient transduction of sensory neurons at low multiplicities of infection (MOIs) and sustained transgene expression within a 28-day culture period. Interestingly, the lentivirus vector selectively transduced neurons in murine cultures, in contrast to human cultures, in which Schwann and fibroblast-like cells were also transduced. Recombinant AAV transduced all three cell types in both mouse and human cultures. After direct microinjection of murine DRG explants, maximal transduction efficiencies of 20 and 200 transducing units per neuronal transductant were achieved with AAV and lentivirus vectors, respectively. Most importantly, both vectors achieved efficient and sustained transduction of human sensory neurons in dissociated cultures, thereby directly demonstrating the exciting potential of these vectors for gene therapy applications in the PNS.

The adenovirus E4 ORF6 and E1b 55 kDa proteins cooperate in a p53-independent manner to enhance transduction by recombinant adeno-associated virus vectors

The observation that exposure of target cells to genotoxic stress or adenovirus infection enhances recombinant adeno-associated virus (rAAV) transduction is an important lead towards defining the rAAV transduction mechanism, and has significant implications for the exploitation of rAAV in gene therapy applications. The adenovirus-mediated enhancement of rAAV transduction has been mapped to the E4 ORF6 gene, and expression of E4 ORF6 alone has been considered necessary and sufficient to mediate this effect. Since p53 subserves an important function in the cellular response to genotoxic stress, and interacts with the E4 ORF6 gene product during adenovirus infection, we hypothesized that p53 function might be essential to the rAAV enhancement resulting from these cellular insults. In the current study, using the p53-null cell lines H1299 and Saos-2, we find that p53 is not essential to either genotoxic stress or adenovirus-mediated enhancement of rAAV transduction. We further demonstrate using HeLa, H1299 and Saos-2 cells that E4 ORF6 expression alone is not sufficient to enhance rAAV transduction and that coexpression of the adenovirus E1b 55 kDa protein is necessary. Together, these observations indicate that the mechanism by which adenovirus infection enhances rAAV transduction involves cooperative and interdependent functions of the E4 ORF6 and E1b 55 kDa proteins that are p53-independent.