Rare Childhood Cancer Research Articles

EPCO-05. GENOMIC AND CLINICAL INSIGHTS FROM A LARGE-SCALE STUDY OF 172 RETINOBLASTOMAS

Abstract Retinoblastoma, a pediatric ocular cancer, is the only central nervous system tumor visible without specialized tools, readily detectable with the naked eye. This rare childhood cancer is mainly driven by mutations in RB1 or MYCN amplification, posing significant challenges in pediatric oncology. We conducted whole exome sequencing on 172 retinoblastoma tumors along with matched blood DNA from 171 patients, which included 119 unilateral, 49 bilateral, and three trilateral cases. Our analysis identified pathogenic variants in RB1 in 76 patients and MYCN duplication in 79 cases, highlighting their crucial roles in the disease. Additionally, we found mutations in RPTOR and TSC2, components of the mTOR signaling pathway, in two patients. Notably, our copy number alteration analysis revealed recurrent arm-level changes, including gains on 1q (23.3%), 2p (20.9%), and especially 6p (41.3%), along with other changes such as 5p gain (8.1%), 17q gain (8.1%), and 16q loss (5.8%). Our findings link these genetic alterations to specific clinical features; for instance, 6p gains were associated with Rubeosis, subretinal seeds, and tumor LC beyond, while 17q gains were linked to Rubeosis. Furthermore, gene collapsing techniques identified MATR3 and CYP4F2 as additional novel retinoblastoma-related genes, and module identification analysis pinpointed retinoblastoma-associated modules including HLA-DRB1-CBL, LPAR2, RB1, and TRIM28. Our study, the largest cohort of its kind, underscores the importance of next-generation sequencing from understudied populations in uncovering the complex genetic landscape of retinoblastoma, emphasizing the potential of precision medicine to enhance therapeutic strategies and improve outcomes for retinoblastoma patients.

Comprehensive analysis of constitutional mismatch repair deficiency-associated non-Hodgkin lymphomas in a global cohort.

Constitutional mismatch repair deficiency syndrome (CMMRD) is a rare childhood cancer predisposition syndrome associated with a broad spectrum of malignancies, including non-Hodgkin lymphomas (NHL). Most patients die due to cancer before the age of 20years. Limited data exist on CMMRD-associated lymphomas and their outcome. We conducted a retrospective study including all CMMRD-associated NHL patients registered before 2020 in the European and North American databases or reported by members of the European Intergroup for Childhood Non-Hodgkin Lymphoma (EICNHL). Events considered to define event-free survival included relapse/progression, second malignancy (SML), or death, whichever occurred first. The analysis included 74 patients, with 20 having multiple metachronous NHL. The median age at diagnosis was 9.4years. Previous malignancies were reported in 36% of the patients, café au lait spots in 96%, and consanguinity in 54%. The initial lymphoma subtypes were 53 T-cell lymphoblastic lymphomas (T-LBL), four B-lymphoblastic lymphomas, and 17 mature B-cell non-Hodgkin lymphoma (B-NHL). All patients were treated with curative intent, with current chemotherapy regimens adapted to their subtype. The median follow-up was 8.7years. After the first lymphoma, the 5-year event-free and overall survival rates were, respectively, 23.5% [95% confidence interval (CI): 14.9-35.1] and 61.5% [95% CI: 49.6-72.1]. The 5-year cumulative risk of progression/relapse, SML or death as a first event was 20.8%, 52.9%, and 2.7%. Standard treatments for sporadic NHL are effective in most CMMRD-associated NHL cases, but multiple malignancies, including lymphomas, impair prognosis. Future strategies should evaluate the potential of less genotoxic therapies, including immunotherapy, in preventing SMLs while maintaining effective control of NHL.

Pediatric brainstem glioma: a rare childhood cancer - clinical profile, treatment, and challenges of management - a single-center experience from a developing country

Introduction: Brainstem gliomas (BSGs) occur in the brainstem, located at the base of the brain. BSGs account for 10-20% of all primary CNS tumors. In a hospital-based study conducted at NICRH, BSGs constituted 7.69% of all childhood brain tumors. Objective: To determine the clinical profiles of childhood BSGs and assess the outcomes of pediatric BSGs while addressing the challenges of management. Methodology: It was a cross-sectional prospective study with a sample size of 44. We included all children during the study period and analyzed their data.The children were under 18 years of age. The study period was January 2020 and October 2022 at the Department of Pediatric Hematology and Oncology at the National Institute of Cancer Research and Hospital (NICRH), Bangladesh. Results: There were 44 patients, comprising 29 males and 15 females. The mean age of onset was 7 years. The majority (43.2%) of children fell within the 5-9 years age group. The most common symptoms were limb weakness, ataxia, and vision defects. The duration of symptoms varied from 10 days to 2 years. Sixteen of the patients experienced intracranial hypertension, which led to the development of hydrocephalus. The lesions were pontine in 18 cases, involving the entire brainstem in 13 cases, both pons and medulla in 7 cases, and medulla in 3 cases. Six patients underwent surgical intervention with histological evaluation, revealing astrocytoma (9.1%), oligodendroglioma (2.3%), and ependymoma (2.3%). Twenty-four (54.5%) patients received treatment, while others were unable to do so. The follow-up period extended to 12 months from the last enrollment. Only 8 patients completed both chemotherapy and radiotherapy treatments; other children discontinued or abandoned treatment due to financial constraints or the unavailability of 3D radiotherapy. Out of 44 children, a total of 41 patients passed away, with a mean survival period of 3.9 months. This is due to the high treatment cost in the private sector and disorganized government medical services for children with cancer. Conclusion: Most of the tumors in this series were located in the pons and demonstrated aggressive characteristics. The majority of our patients did not have access to radiotherapy due to their poor economic condition and the inadequate management of our government health system.

STEM-06. THE ROLE OF SHH SIGNALING PATHWAY IN RETINOBLASTOMA INITIATION AND PROGRESSION

Abstract BACKGROUND Retinoblastoma is a rare childhood cancer of the retina that shows the biallelic loss of RB1 in nearly 95% of cases. It was reported that SHH pathway proteins, such as SHH, GLI1, and GLI2, are aberrantly high in human retinoblastoma, and high GLI2 expression is associated with aggressive clinicopathological features. Thus, we assessed whether activation of SHH pathway by overexpression of Gli2 or SMO induces the initiation of retinoblastoma. METHODS We generated a Cre-activated, Doxycycline (Dox)-controlled transgenic model to induce SMO or Gli2 expression in developing retina. In this transgenic mouse, expression of Smo or Gli2A is under the control of TRE, which permits temporal and spatial expression of Smo or Gli2A by administering/withdrawing doxycycline (DOX). RESULTS We fed the triple transgenic mice (Chx10-Cre/R26-LSL-rtTA/tetO-Smo or Chx10-Cre/R26-LSL-rtTA/tetO-Gli2A starting from E0 or P5. Our studies demonstrated that control littermates (Cre-) did not show any abnormalities, while mice with triple transgenes developed tumors in the bilateral eyes with 100% morbidity. The animals showed symptoms of leukocoria at P0-P3 or P25-p30 if the oncogenes were initiated at E0 or P5 respectively. The tumor cells were highly proliferative and expressed retina progenitor cell specific marker of Sox2, showing aberrant expression of pRB, CDK4/6, and CCND1. CONCLUSIONS Our results demonstrate that overexpressing Smo or Gli2 in Chx10+ cells induce rapid tumor formation in mouse retina. In future study, we plan to (i) investigate the impact of Shh pathway activation in RPCs on RB tumorigenesis within the context of Rb1 loss; (ii) define the molecular mechanisms underlying tumor initiation and progression; and (iii) evaluate whether targeting SHH pathway prevents or delays tumor initiation and progression using our Gli2-driven mouse model and patient-derived xenografts.

Strategies for diagnosis and management of CMMRD in low-resource countries: report of a Tunisian family.

Constitutional Mismatch Repair Deficiency (CMMRD) is a rare childhood cancer predisposition syndrome, caused by biallelic pathogenic germline variants in the mismatch repair genes. Diagnosis and management of this syndrome is challenging, especially in low-resource settings. This study describes a patient diagnosed with colorectal cancer and grade 3 astrocytoma at the age of 11 and 12 respectively. Immunohistochemistry analysis showed a loss of MSH2 and MSH6 protein expression in CRC tissues of the patient. We identified by Targeted Exome Sequencing a homozygous pathogenic germline variant in exon 9 of the MSH6 gene (c.3991C > T; p.Ala1268Glyfs*6). Genetic investigation of the family showed that the father was heterozygous for the identified pathogenic variant while the brother was wild type for this variant. Our study highlights the importance of a correct and timely diagnosis of CMMRD which can have implications for treatment. It also underlines the imperative need to enhance awareness, diagnostic standards, and surveillance that are crucial for patients and their families.

Treatment outcomes in patients with Ewing sarcoma of the spine in a resource-challenged setting: 17-year experience from a single center in India

Ewing sarcoma (ES) of the spine is a rare childhood cancer with sparse literature on treatment outcomes. We aimed to describe survival outcomes and prognostic factors in patients with spinal ES treated at a single institute in a resource-challenged setting. We conducted a retrospective analysis of patients with spinal ES registered at a tertiary care oncology center between 2003–2019. Clinical patient data was retrieved from hospital records. Cox regression analysis was used to identify the association of baseline clinical parameters with event free survival (EFS) and overall survival (OS). A cohort of 85 patients was analyzed including 38 (45%) patients with metastatic disease. The median age was 15 years with 73% being male. Local therapy was administered in 62 (72.9%) patients with surgery alone in 8 (9.4%), radiotherapy alone in 36 (42.4%) and both in 18 (21.2%) patients. A higher proportion of males received local therapy than females (80.3% versus 59.1%; p = 0.049). The median EFS and OS were 20.1 and 28.6 months, respectively. On univariable analysis, age ≤ 15 years, female sex, serum albumin ≤3.5 g/dL and hemoglobin ≤11 g/dL were associated with inferior EFS while younger age, female sex, hypoalbuminemia and metastatic disease were associated with inferior OS. On multivariable analysis, only hypoalbuminemia was predictive for inferior EFS (HR:2.41; p = 0.005) while hypoalbuminemia (HR:2.06;p = 0.033) and female sex (HR:1.83; p = 0.046) were associated with inferior OS. We concluded that hypoalbuminemia confers poor prognosis in ES spine. Survival outcomes are poorer in females treated in our setting, possibly due to prevailing sex-based biases.

Single cell RNA sequencing analysis of tumor responses to triple drug oral immunotherapy in dogs with osteosarcoma

Abstract Osteosarcoma constitutes a rare childhood cancer that is associated with dismal outcomes. As such, there is a need to develop non-invasive immunotherapeutic approaches to treat this aggressive malignancy. To address this need, we described the cellular heterogeneity in spontaneously occurring canine osteosarcoma tumors then evaluated how treatment with adjuvant immunotherapy altered the tumor microenvironment. We investigated the effects of a triple drug immunotherapeutic (orally administered losartan, ladarixin, and toceranib) that was designed to deplete immune suppressive macrophages and promote antitumor immunity. The treated cohort of dogs were given the adjuvant immunotherapy for 14 days prior to amputation, while naïve samples were collected from unrelated dogs undergoing amputation to treat a primary osteosarcoma tumor. In total, we completed single cell RNA sequencing on 6 naïve dogs and 6 treated dogs to profile just under 100,000 cells. Unsupervised clustering revealed 30 unique cell populations with T cells, macrophages, and neutrophils making up the majority of immune infiltrates. Evaluation of changes to the cellular proportions following treatment revealed a marked reduction in macrophages, which suggests the combination immunotherapy was able to alter the tumor microenvironment. Overall, this study provides unique insights into the heterogeneity within canine osteosarcoma tumors and highlights the impacts of adjuvant immunotherapy on tumor infiltrating immune cell transcriptional programs. T32 OD012201 U01 CA5341458 Shipley family foundation

Maternal use of hormonal contraception and rare cancer types in children: A nationwide PECH cohort study

AbstractBackgroundMaternal hormonal contraception use has been associated with an increased risk of leukaemia and central nervous system (CNS) tumours in children. However, little is known about the association with other, less common childhood cancer types. We assessed associations between maternal hormonal contraceptive use and all main types of childhood cancer, excluding leukaemia and CNS tumours.MethodsIn this nationwide PECH cohort study, we followed all Danish children liveborn in 1996–2014 (n = 1 185 063) from birth until 2018. Registry information was extracted on maternal filled prescriptions of hormonal contraception and childhood cancer diagnoses (age at diagnosis <20 years). The exposure of interest was maternal ‘recent use’ of hormonal contraception (use ≤3 months before or during pregnancy, except for injections, implants and intrauterine devices with a different timeframe), compared to no use. Cox proportional hazard models were used to estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for childhood cancer according to any use, regiment (combined/progestin‐only) and administration route (oral/non‐oral).ResultsDuring 15 335 990 person‐years of follow‐up, 1384 children were diagnosed with a rare cancer type. Compared to children of mothers with no use of hormonal contraception, maternal recent use of hormonal contraception was not statistically significantly associated with any of the childhood cancers assessed. Except for maternal recent use of non‐oral hormonal contraception, where a hazard ratio (HR) of 6.90 (95% CI: 1.31, 36.47) for hepatic tumours was found. However, this finding was based on a small number of children and if causal, this would result in one additional case per about 99 500 person‐years of follow‐up.ConclusionsMaternal use of hormonal contraception up to or during pregnancy was not associated with nearly every rare childhood cancer type assessed, compared to no use.

Abstract 3571: The ITCC-P4 sustainable platform of fully characterized PDXs supports the preclinical proof-of-concept drug testing of high-risk pediatric tumor models

Abstract Cancer represents a leading cause of death by disease in childhood. Pediatric tumors exhibit a high intertumoral heterogeneity, as different tumor types and subtypes have emerged with peculiar molecular and clinical features; however, compared to cancer in adults, pediatric tumors are rare and mostly present with lower mutational burden. The lack of specific therapeutic options represents the main current challenge; systematic, multi-disciplinary approaches are required to accelerate drug development and ultimately to find cures for all children with cancer. The EU funded “Innovative Therapies for Children with Cancer–Pediatric Preclinical Proof-of-Concept Project” (ITCC-P4; www.itccp4.eu) consortium consists of a public-private partnership including academic and industrial partners with the goal of developing a large-scale platform comprising >400 patient-derived xenograft (PDX) models representing high-risk pediatric cancers. Currently, this collection of PDX models includes the most common types of pediatric tumors, such as leukemia (n=28), bone and soft-tissue sarcomas (n=154), CNS tumors (n=96) and neuroblastomas (n=38), as well as other rare childhood cancers, such as hepatoblastomas (n=20) and malignant rhabdoid tumors (n=18); PDX models have been generated either from primary (n=206) or relapse (n=118) disease. In order to: a) investigate the biology of the pediatric PDX models in a high-throughput and systematic fashion, b) assess whether they accurately reflect the molecular features of the corresponding primary tumor and, c) identify potential new suitable biomarkers, we performed a comprehensive molecular characterization (whole-exome and low-coverage whole-genome sequencing; DNA methylation profiling; RNAseq and gene expression profiling) of the PDX models, as well as their matching human tumors and germline samples. These data contributed to the stratification of the PDX models based on their mutational status and emerging molecular vulnerabilities to inform in vivo drug testing in all these PDX models. This proof-of-concept drug testing has been conducted defining, for each group of models, a panel of single compounds (SOC n=3; novel targeted therapies, n=6) or combinations (with each other or with chemo- or radiotherapy). All processed molecular and drug-testing data are collected in the consortium´s centralized data repository (https://r2.amc.nl) allowing data downstream analysis, visualization and interpretation. Taken together, the ITCC-P4 sustainable platform represents a validated and powerful tool to investigate the biology of pediatric cancer based on the establishment, characterization and preclinical testing of pediatric cancer PDX models, ultimately envisaged to contribute the development of innovative therapeutic options for childhood cancer patients. Citation Format: Aniello Federico, Apurva Gopisetty, Didier Surdez, Yasmine Iddir, Alexandra Saint-Charles, Justyna Wierzbinska, Andreas Schlicker, Richard Volckmann, Danny Zwijnenburg, Sara Colombetti, Olaf Heidenreich, Fatima Iradier, Heinrich Kovar, Jan-Henning Klusmann, Klaus-Michael Debatin, Simon Bomken, Christina Guttke, Maureen M. Hattersley, Frédéric Colland, Ashley Strougo, María José Guillén, Louis Chesler, Chris Jones, Maria Eugénia Marques da Costa, Katia Scotlandi, Massimo Moro, Beat Schäfer, Marco Wachtel, Johannes Gojo, Walter Berger, Ángel Montero Carcaboso, Dennis Gürgen, Jens Hoffmann, Emilie Indersie, Stefano Cairo, Julia Schueler, Nicole Huebener, Johannes H. Schulte, Jan J. Molenaar, Birgit Geoerger, David J. Shields, Hubert N. Caron, Gilles Vassal, Lou F. Stancato, Lou F. Stancato, Stefan M. Pfister, Natalie Jäger, Jan Koster, Marcel Kool, Gudrun Schleiermacher. The ITCC-P4 sustainable platform of fully characterized PDXs supports the preclinical proof-of-concept drug testing of high-risk pediatric tumor models. [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 3571.

Abstract 6545: Investigating secondary findings in a pediatric cancer cohort: preliminary findings

Abstract Purpose: An expected outcome following germline genome sequencing in oncology is the discovery of ‘secondary findings’ (SFs). SFs comprise pathogenic(P)/likely P (LP) germline variants in cancer genes not typically associated with the presenting cancer, in addition to germline variants of uncertain significance (VUS) to the patient’s cancer. Due to the rarity of childhood cancers and a dearth of studies analyzing SFs, many pediatric SFs are categorized as VUS without clinical interpretation. Interpreting SFs poses significant challenges: VUSs and other SFs are frequently not included in clinical molecular reports, and even when reported (often through research), their clinical utility and long-term impact on patient health are unclear. However, we know VUSs can have clinical importance because some VUSs, when investigated thoroughly, have been reclassified as pathogenic predictors of significant health conditions in children. We hypothesize that an in-depth characterization of the landscape of germline SFs/VUSs across a diverse pediatric cancer cohort will reveal new roles of these genes and mutations in pediatric cancers. Methods: To explore germline SFs in pediatric cancer patients, we analyzed germline whole-genome sequencing (WGS) data for patients with rare, relapsed, refractory, and metastatic childhood cancers enrolled in the SickKids Cancer Sequencing Program (KiCS). We developed a custom analysis pipeline to identify germline single-nucleotide variants and indels deemed SFs, auto-classify their pathogenicity (ex. P, LP, or VUS) using CharGer, filter for PanCanAtlas-indicated cancer predisposition genes, and sort the remaining variants by cancer and non-cancer associations. Results: The KiCS cohort (n = 511) encompassed over 133 different tumor types; the median age of participants was 14 years (SD = 10.27) and 55% of patients were male. Ongoing work in our lab will catalogue the frequency and distribution of SFs in KiCS and analyze germline variants by subgroup (gene, tumor subtype, stage, demographics, gene function). We will also compare SF prevalence in KiCS to the general population using the gnomAD dataset. Results from preliminary analyses of this cohort will be presented. Significance: SFs/VUSs are under-utilized in cancer management. This work advances the holistic understanding of germline genomics in pediatric oncology and the roles of SFs in disease. Future studies will evaluate SFs by patient ancestry and validate cancer associations through the evaluation of allelic imbalance/loss of heterozygosity in matched tumor genomes. Citation Format: Safa Majeed, Stephenie Prokopec, Brianne Laverty, Vallijah Subasri, Michael Taylor, Yvonne Bombard, Trevor Pugh, Adam Shlien, Anita Villani, David Malkin. Investigating secondary findings in a pediatric cancer cohort: preliminary findings. [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 6545.

Abstract 4670: True bench-to-bedside science: An international pilot study modeling hard-to-cure pediatric cancers to prioritize therapeutic intervention

Abstract There has been dramatic improvement in treatment outcomes for many pediatric cancers over the last three decades. However, for the 20% of young people with relapsed or refractory cancer, the prognosis remains grim. Canada’s PRecision Oncology For Young peopLE (PROFYLE) and Australia’s Zero Childhood Cancer (ZERO) programs, leverage nation-wide scientific and clinical oncology expertise to provide personalized precision medicine to children, adolescent and young adult (CAYA) cancer patients who lack treatment options. Beyond improving the lives of young cancer patients nationally, PROFYLE and ZERO have partnered to create an international pipeline for knowledge sharing and sample acquisition. A key component of both programs is the use of mice for patient-derived xenografts (PDXs). However, long lead times for mouse PDX generation make the timely return of preclinical drug response data challenging. PROFYLE has uniquely incorporated zebrafish larval xenografts, which have the potential to provide comparable information in a clinically actionable timeframe. In a pilot study, we compared retrospective matched ZERO patient and mouse PDX therapeutic response data with prospective zebrafish larval PDX data as a proof-of-principle that drug efficacy signals were maintained across model systems. Three ZERO avatars: high-risk neuroblastoma, Ewing’s sarcoma, and anaplastic large cell lymphoma were shipped from Australia to Canada and transplanted into 48h casper zebrafish. Following dose optimization, zebrafish PDXs were treated with targeted single and combination drug treatments by immersion therapy. Strikingly, in as little time as a week, cell proliferation rates and drug responses to single agents and combinatorial therapy in zebrafish PDXs recapitulated mouse and patient data. To expand on this pilot project, we tested additional patient samples, including multiple subtypes of sarcomas, T-cell acute lymphoblastic leukemia and an embryonal tumor with multilayered rosettes. Results further validated the practical utility of the zebrafish larval PDX model and in fact provided drug response data when mouse PDX data were unavailable. This study demonstrates the robustness and feasibility of the zebrafish larval PDX model as a preclinical tool for personalized precision therapeutic decision-making and highlights the value of international collaboration in improving outcomes of rare childhood cancers. Citation Format: Nadine Azzam, Nicole Melong, Lissandra Tuzi, Lisa Pinto, Jamie I. Fletcher, Alvin Kamili, Biljana Dumevska, Loretta Lau, Jennifer A. Chan, Donna L. Senger, Stephanie A. Grover, Michelle Haber, David Malkin, Jason N. Berman. True bench-to-bedside science: An international pilot study modeling hard-to-cure pediatric cancers to prioritize therapeutic intervention. [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 4670.

Constitutional Microsatellite Instability, Genotype, and Phenotype Correlations in Constitutional Mismatch Repair Deficiency

Constitutional mismatch repair deficiency (CMMRD) is a rare recessive childhood cancer predisposition syndrome caused by germline mismatch repair variants. Constitutional microsatellite instability (cMSI) is a CMMRD diagnostic hallmark and may associate with cancer risk. We quantified cMSI in a large CMMRD patient cohort to explore genotype-phenotype correlations using novel MSI markers selected for instability in blood. Three CMMRD, 1 Lynch syndrome, and 2 control blood samples were genome sequenced to >120× depth. A pilot cohort of 8 CMMRD and 38 control blood samples and a blinded cohort of 56 CMMRD, 8 suspected CMMRD, 40 Lynch syndrome, and 43 control blood samples were amplicon sequenced to 5000× depth. Sample cMSI score was calculated using a published method comparing microsatellite reference allele frequencies with 80 controls. Thirty-two mononucleotide repeats were selected from blood genome and pilot amplicon sequencing data. cMSI scoring using these MSI markers achieved 100% sensitivity (95% CI, 93.6%-100.0%) and specificity (95% CI 97.9%-100.0%), was reproducible, and was superior to an established tumor MSI marker panel. Lower cMSI scores were found in patients with CMMRD with MSH6 deficiency and patients with at least 1 mismatch repair missense variant, and patients with biallelic truncating/copy number variants had higher scores. cMSI score did not correlate with age at first tumor. We present an inexpensive and scalable cMSI assay that enhances CMMRD detection relative to existing methods. cMSI score is associated with mismatch repair genotype but not phenotype, suggesting it is not a useful predictor of cancer risk.

EPCO-28. DOT1L AND PRC2 REGULATE A SHARED EPIGENETIC MECHANISM IN GLIOBLASTOMA AND MIXED LINEAGE LEUKEMIA

Abstract Glioblastoma (GBM) is the most aggressive adult brain tumor, with a median survival of 15 months despite current treatments. We recently established that the epigenetic regulator Disruptor of Telomeric Silencing-1-Like (DOT1L) was essential for the growth of brain tumor stem cells (BTSCs), which are thought to underlie GBM tumor initiation and treatment resistance. Given the previously recognized importance of DOT1L histone methylation for the regulation of the similarly rare and aggressive childhood cancer, Mixed Lineage Leukemia (MLL), we interrogated for common mechanisms in both BTSCs and MLL cells, that overlap due to the epigenetic role of DOT1L. To gain a more detailed perspective of the importance of the DOT1L epigenetic mark in BTSCs, we performed a chemogenomic screen using the DOT1L inhibitor, EPZ-5676. Results from this screen revealed genes from transcriptional and epigenetic complexes required for a therapeutic response to DOT1L inhibition in BTSCs. Gene targeting approaches and growth assays further identified the Polycomb Repressive Complex 2 (PRC2) as a common determining factor for the growth response of both BTSCs and MLL cells following DOT1L inhibition. Furthermore, analysis of the chromatin accessibility changes regulated by DOT1L and PRC2 histone methylation identified both shared and unique epigenetic characteristics of GBM and MLL. The extent to which these shared mechanisms underpin the pathogenic process in these distinct diseases is being further investigated by assessing the divergence in transcriptional responses that emerge from this common epigenetic phenomenon. The findings from this study will provide insight into the importance of shared epigenetic mechanisms that underlie the tumorigenesis of unique cancers affecting the brain and blood.

Machine learning for rhabdomyosarcoma histopathology

AbstractCorrectly diagnosing a rare childhood cancer such as sarcoma can be critical to assigning the correct treatment regimen. With a finite number of pathologists worldwide specializing in pediatric/young adult sarcoma histopathology, access to expert differential diagnosis early in case assessment is limited for many global regions. The lack of highly-trained sarcoma pathologists is especially pronounced in low to middle-income countries, where pathology expertise may be limited despite a similar rate of sarcoma incidence. To address this issue in part, we developed a deep learning convolutional neural network (CNN)-based differential diagnosis system to act as a pre-pathologist screening tool that quantifies diagnosis likelihood amongst trained soft-tissue sarcoma subtypes based on whole histopathology tissue slides. The CNN model is trained on a cohort of 424 centrally-reviewed histopathology tissue slides of alveolar rhabdomyosarcoma, embryonal rhabdomyosarcoma and clear-cell sarcoma tumors, all initially diagnosed at the originating institution and subsequently validated by central review. This CNN model was able to accurately classify the withheld testing cohort with resulting receiver operating characteristic (ROC) area under curve (AUC) values above 0.889 for all tested sarcoma subtypes. We subsequently used the CNN model to classify an externally-sourced cohort of human alveolar and embryonal rhabdomyosarcoma samples and a cohort of 318 histopathology tissue sections from genetically engineered mouse models of rhabdomyosarcoma. Finally, we investigated the overall robustness of the trained CNN model with respect to histopathological variations such as anaplasia, and classification outcomes on histopathology slides from untrained disease models. Overall positive results from our validation studies coupled with the limited worldwide availability of sarcoma pathology expertise suggests the potential of machine learning to assist local pathologists in quickly narrowing the differential diagnosis of sarcoma subtype in children, adolescents, and young adults.

Recent Advances in Renal Medullary Carcinoma.

Renal medullary carcinoma (RMC) is a rare renal malignancy that has been associated with sickle hemoglobinopathies. RMC is aggressive, difficult to treat, and occurs primarily in adolescents and young adults of African ancestry. This cancer is driven by the loss of SMARCB1, a tumor suppressor seen in a number of primarily rare childhood cancers (e.g., rhabdoid tumor of the kidney and atypical teratoid rhabdoid tumor). Treatment options remain limited due in part to the limited knowledge of RMC biology. However, significant advances have been made in unraveling the biology of RMC, from genomics to therapeutic targets, over the past 5 years. In this review, we will present these advances and discuss what new questions exist in the field.

Rare Childhood Cancer Burden in a Tertiary Care Hospital of Dhaka, Bangladesh

Background: Accurate childhood cancer burden data are crucial for resource planning and health policy prioritization. In Bangladesh we have no national population based cancer registry. Data about the total burden of childhood cancer in our country is unknown. But a hospital based cancer registry is the cheapest way to assess the tumor burden of a nation. So we investigate the total pediatric cancer burden and the percentage of different types of rare childhood cancers (RCC) of National Institute of Cancer Research and Hospital (NICRH), Dhaka, during the year 2014 – 2018. Aim: To investigate the total number of pediatric cancers, frequency of different types of rare cancer and percentage of rare childhood cancer in the Pediatric Hematology and Oncology (PHO) department. Methods: Data were collected from all pediatric (0-17 years) patients between the year 2014 and 2018 prospectively. Definitive diagnosis of cases were established by histopathological and or immunohistochemical study. As we have no population-based cancer registry, we considered the rare tumors in our study according to the Children's Oncology Group (COG) and the German Childhood Cancer Registry (GCCR). Results: Total number of childhood cancers and RCC was 2242 and 351 respectively. Percentage of rare tumors was 15.66% in our center. Benign rare tumors were 18.52% (N-65) cases. Common age group was the 5-9 years group (54.13 %). Most common RCC groups were Non-Rhabdomyosarcoma soft tissue sarcoma (NRSTS) constituting 49.29 %, followed by Malignant epithelial neoplasms and melanomas (38.18%). Diagnostic delay was 3.52 months. Most common malignancy was Synovial Sarcoma (N-40, 11.39%), Peripheral Neuroectodermal Tumor (N-39, 11.11%), Nasopharyngeal carcinoma (N-35, 9.97%), Malignant small round cell tumor (N-31, 8.83%) and Carcinoma rectum and colon (N-23, 6.55%). Conclusion: We have found that our Institutional (NICRH) rare tumor rate (15.66%) was a bit higher than US national RCC (15%). Though Institutional cancer data reflect the national burden, to estimate the accurate number and percentage of RCC, National Cancer Registry is needed.

New Developments in the Pathogenesis, Therapeutic Targeting, and Treatment of H3K27M-Mutant Diffuse Midline Glioma.

Simple SummaryH3K27M-mutant diffuse midline glioma is a rare childhood cancer originating in midline brain structures. The H3K27M mutation substitutes an amino acid on histone H3 that promotes gene expression and tumor growth. This cancer has a dismal prognosis and requires new and better treatment approaches. This review discusses controversies regarding tumor biopsy and summarizes molecular tumor characteristics that are therapeutic targets. We describe preclinical studies and clinical trials utilizing immunotherapy, radiation, and chemotherapy against this cancer. H3K27M-mutant diffuse midline gliomas (DMGs) are rare childhood central nervous system tumors that carry a dismal prognosis. Thus, innovative treatment approaches are greatly needed to improve clinical outcomes for these patients. Here, we discuss current trends in research of H3K27M-mutant diffuse midline glioma. This review highlights new developments of molecular pathophysiology for these tumors, as they relate to epigenetics and therapeutic targeting. We focus our discussion on combinatorial therapies addressing the inherent complexity of treating H3K27M-mutant diffuse midline gliomas and incorporating recent advances in immunotherapy, molecular biology, genetics, radiation, and stereotaxic surgical diagnostics.

Enhancement of Neuroblastoma NK-Cell-Mediated Lysis through NF-kB p65 Subunit-Induced Expression of FAS and PVR, the Loss of Which Is Associated with Poor Patient Outcome.

Simple SummaryNeuroblastoma (NB) cells adopt several molecular strategies to evade the Natural Killer (NK)-mediated response. Herein, we found that the overexpression of the NF-kB p65 subunit in NB cell lines upregulates the expression of both the death receptor FAS and the activating ligand PVR, thus rendering NB cells more susceptible to NK-cell-mediated apoptosis, recognition, and killing. These data could provide a clue for a novel NK-cell-based immunotherapy of NB. In addition, array CGH analysis performed in our cohort of NB patients showed that loss of both the FAS and PVR genes correlated with low survival, thus revealing a novel biomarker predicting the outcome of NB patients.High-risk neuroblastoma (NB) is a rare childhood cancer whose aggressiveness is due to a variety of chromosomal genetic aberrations, including those conferring immune evasion. Indeed, NB cells adopt several molecular strategies to evade recognition by the immune system, including the downregulation of ligands for NK-cell-activating receptors. To date, while molecular strategies aimed at enhancing the expression of ligands for NKG2D- and DNAM-1-activating receptors have been explored, no evidence has been reported on the immunomodulatory mechanisms acting on the expression of death receptors such as Fas in NB cells. Here, we demonstrated that transient overexpression of the NF-kB p65 subunit upregulates the surface expression of Fas and PVR, the ligand of DNAM-1, thus making NB cell lines significantly more susceptible to NK-cell-mediated apoptosis, recognition, and killing. In contrast, IFNγ and TNFα treatment, although it induced the upregulation of FAS in NB cells and consequently enhanced NK-cell-mediated apoptosis, triggered immune evasion processes, including the strong upregulation of MHC class I and IDO1, both of which are involved in mechanisms leading to the impairment of a proper NK-cell-mediated killing of NB. In addition, high-resolution array CGH analysis performed in our cohort of NB patients revealed that the loss of FAS and/or PVR genes correlated with low survival independently of the disease stage. Our data identify the status of the FAS and PVR genes as prognostic biomarkers of NB that may predict the efficacy of NK-cell-based immunotherapy of NB. Overall, restoration of surface expression of Fas and PVR, through transient upregulation of NF-kB, may be a clue to a novel NK-cell-based immunotherapy of NB.

A review of Leila Rose Foundation support for families affected by rare childhood cancer in Australia over the past decade.

BackgroundThe Leila Rose Foundation (“the Foundation”) was established in April 2011, to address financial toxicity as well as the gaps in knowledge and support for families affected by a rare childhood cancer diagnosis in Australia.AimThe aim of this brief report is to analyze the diagnostic trends surrounding the rare cancer diagnoses for patients referred to the Foundation over the past decade and to present case studies evaluating the role of the Foundation's Family Support Coordinator in providing tailored, individualized support for families.MethodsEligibility for family support is restricted to children ≤ 14 years of age at diagnosis with a cancer that has an incidence less than 5% of all childhood cancers in Australia as reflected by national registry data. The analysis of diagnostic trends in this report, was based upon a systematic review of enrolment records. The role of the Family Support Coordinator is presented in four different case studies.ResultsAs at 1 November 2020, the Foundation has supported 197 families affected by rare childhood cancer. Financial support of $825,000 has been provided directly to these families. Enrollment records demonstrate that 35 patients representing 18% of all enrollments have had a unique diagnosis that has not been recorded for any other enrolled patient highlighting that these diagnoses are very rare. The most frequent diagnoses have included Medulloblastoma, Ewing's Sarcoma and Wilm's Tumor (20, 19, 19 patients respectively). The Family Support Coordinator role has provided individualized support for families which has been greatly appreciated based upon ad hoc family feedback.ConclusionsChallenges remain in terms of improving outcomes for families affected by rare childhood cancer. The Foundation is committed to leaving no stone unturned and delivering its unique support services to families in order to reduce the burden caused by a rare childhood cancer diagnosis both now and in the future.

Rare pediatric malignancies - A twenty year experience from an oncology institute in South India

BackgroundRare pediatric malignancies, as the name suggests, are not very frequently encountered in day to day practice. The European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) defines a rare childhood cancer as one that has an incidence rate ≤ 2 per million per year, is not considered in clinical trials, or both. In view of the sheer rarity of these tumors, they are treated mostly at the physician's discretion. We have compiled our department's twenty-year experience with such rare tumors. MethodsWhile rare tumors are those whose incidence is less than 2 per million in the Pediatric age group, and for practical purposes, given our estimated catchment population of 2–3 million children, those cases seen with <5 children diagnosed per year were considered rare in our study. Data collection was done from our medical records department using patient files. SPSS for Mac version 24. Armonk, NY: IBM Corp. was used for statistical analysis. Results133 cases of rare tumors were documented in 20 years (2000–2019). The most common among these was non rhabdomyosarcoma soft tissue sarcoma (NRSTS). Other rare tumors we encountered were adrenocortical carcinoma, carcinoma of colon, phaechromocytoma, extrarenal rhabdoid tumor, renal cell carcinoma and hepatocellular carcinoma. A male preponderance was noted with boys: girls (1.8:1). Thirty three percent of the cases were contributed by children above 10 years while infants constituted 15.8%. Twelve percent presented with metastasis. The median time to diagnosis overall in rare tumors was 29 days. Twenty-six children defaulted due to several reasons. Three-year progression free survival in the remaining 107 patients was 58.3%. ConclusionCentral pathology review and collaborative trials will be helpful in ensuring uniform treatment protocols in these children, and potentially better outcomes.