A standardized autopsy procurement allows for the comprehensive study of DIPG biology

Research autopsy programmes in oncology: shared experience from 14 centres across the world

While there is a great clinical need to understand the biology of metastatic cancer in order to treat it more effectively, research is hampered by limited sample availability. Research autopsy programmes can crucially advance the field through synchronous, extensive, and high-volume sample collection. However, it remains an underused strategy in translational research. Via an extensive questionnaire, we collected information on the study design, enrolment strategy, study conduct, sample and data management, and challenges and opportunities of research autopsy programmes in oncology worldwide. Fourteen programmes participated in this study. Eight programmes operated 24 h/7 days, resulting in a lower median postmortem interval (time between death and start of the autopsy, 4 h) compared with those operating during working hours (9 h). Most programmes (n = 10) succeeded in collecting all samples within a median of 12 h after death. A large number of tumour sites were sampled during each autopsy (median 15.5 per patient). The median number of samples collected per patient was 58, including different processing methods for tumour samples but also non-tumour tissues and liquid biopsies. Unique biological insights derived from these samples included metastatic progression, treatment resistance, disease heterogeneity, tumour dormancy, interactions with the tumour micro-environment, and tumour representation in liquid biopsies. Tumour patient-derived xenograft (PDX) or organoid (PDO) models were additionally established, allowing for drug discovery and treatment sensitivity assays. Apart from the opportunities and achievements, we also present the challenges related with postmortem sample collections and strategies to overcome them, based on the shared experience of these 14 programmes. Through this work, we hope to increase the transparency of postmortem tissue donation, to encourage and aid the creation of new programmes, and to foster collaborations on these unique sample collections. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Rapid autopsies to enhance metastatic research: the UPTIDER post-mortem tissue donation program

Research on metastatic cancer has been hampered by limited sample availability. Here we present the breast cancer post-mortem tissue donation program UPTIDER and show how it enabled sampling of a median of 31 (range: 5-90) metastases and 5-8 liquids per patient from its first 20 patients. In a dedicated experiment, we show the mild impact of increasing time after death on RNA quality, transcriptional profiles and immunohistochemical staining in tumor tissue samples. We show that this impact can be counteracted by organ cooling. We successfully generated ex vivo models from tissue and liquid biopsies from distinct histological subtypes of breast cancer. We anticipate these and future findings of UPTIDER to elucidate mechanisms of disease progression and treatment resistance and to provide tools for the exploration of precision medicine strategies in the metastatic setting.

Patient-Derived Orthotopic Xenograft Models for High-Grade Pediatric Brain Cancers

Patient-derived orthotopic xenograft (PDOX) mouse models are considered the gold standard for evidence-based preclinical research in pediatric neuro-oncology. This protocol describes the generation of PDOX models by intracranial implantation of human pediatric brain cancer cells into immune-deficient mice, and their continued propagation to establish cohorts of animals for preclinical research.

Pediatric Postmortem Tissue Donation in the Confines of a Pandemic: A Model of Collaboration

BACKGROUND

Obtaining postmortem tissue from pediatric oncology patients is critical to research and may help grieving families heal. Since 2019, the national Gift from a Child program has made significant progress in collecting postmortem tissue from pediatric patients with central nervous system tumors to advance research. This progress was at risk during the onset of the severe acute respiratory syndrome coronavirus 2 pandemic, when some autopsy programs came to a halt.

METHODS

We retrospectively reviewed autopsies of four patients treated at Memorial Sloan Kettering Cancer Center who underwent postmortem examination at Weill Cornell Medicine from June 2020 to March 2021. We collected patient demographics, Do not resuscitate status, time of death and procedure, restrictions due to the coronavirus disease 2019 (COVID-19) pandemic, and results of the tissue analysis.

RESULTS

Three of four specimens were processed within 12 hours of the time of death. Two families required interpreter services to obtain consent. In all cases, tumor aliquots were flash frozen for further study. Cell line generation was successful in one case. All families expressed gratitude both for the opportunity to participate and for the handling of the procedures.

CONCLUSIONS

Despite the sensitive nature of these cases and the challenges presented by COVID-19 restrictions, clinicians should offer the option of a rapid autopsy to caregivers of pediatric patients based on the scientific need and the positive effect it has on grieving families. This article outlines the logistic efforts required for these donations to take place and provides a framework for providers to offer rapid autopsy as an option for families through this program.

Coping with Diffuse Intrinsic Pontine Glioma in Children - Findings from an Interview Study on Bereaved Parents

BACKGROUND

Diffuse midline glioma (DMG) is the most common malignant glioma in early childhood with median survival of only eleven months. This retrospective interview study investigates specific coping strategies and needs of affected parents.

PATIENTS

13 interviews with parents of seven children who died from DMG at the age of five to 16 years were conducted in 2016.

METHOD

The used method is a problem-oriented guided interview with consecutive content and evaluating structuring analysis according to Mayring.

RESULTS

Major inductive category was whether the parents had talked to their children about their upcoming death. All parents stated overall satisfaction and comfort regarding their palliative care. Lack of psycho-social support in families was successfully addressed by involving palliative care.

CONCLUSIONS

Retrospective interview studies in this context are feasible. Early involvement of the palliative care team may relieve burden from affected parents. Open communication about death proved helpful for all involved parties, it may facilitate acceptance of terminal illness and alleviate guilt in parents.Concepts for an open and empowering communication within families and between treatment site and families need continuing adjustment. The Palliative care team may also have a key role regarding early phase trials and molecular studies.

Molecular Alterations in Pediatric Low-Grade Gliomas That Led to Death

Pediatric low-grade gliomas (PLGGs) have excellent long-term survival, but death can occasionally occur. We reviewed all PLGG-related deaths between 1975 and 2019 at our institution: 48 patients were identified; clinical data and histology were reviewed; targeted exome sequencing was performed on available material. The median age at diagnosis was 5.2 years (0.4-23.4 years), at death was 13.0 years (1.9-43.2 years), and the overall survival was 7.2 years (0.0-33.3 years). Tumors were located throughout CNS, but predominantly in the diencephalon. Diagnoses included low-grade glioma, not otherwise specified (n = 25), pilocytic astrocytoma (n = 15), diffuse astrocytoma (n = 3), ganglioglioma (n = 3), and pilomyxoid astrocytoma (n = 2). Recurrence occurred in 42/48 cases, whereas progression occurred in 10. The cause of death was direct tumor involvement in 31/48 cases. Recurrent drivers included KIAA1549-BRAF (n = 13), BRAF(V600E) (n = 3), NF1 mutation (n = 3), EGFR mutation (n = 3), and FGFR1-TACC1 fusion (n = 2). Single cases were identified with IDH1(R132H), FGFR1(K656E), FGFR1 ITD, FGFR3 gain, PDGFRA amplification, and mismatch repair alteration. CDKN2A/B, CDKN2C, and PTEN loss was recurrent. Patients who received only chemotherapy had worse survival compared with patients who received radiation and chemotherapy. This study demonstrates that PLGG that led to death have diverse molecular characteristics. Location and co-occurring molecular alterations with malignant potential can predict poor outcomes.

Toward a standard pathological and molecular characterization of recurrent glioma in adults: a Response Assessment in Neuro-Oncology effort

Regardless of subtype, diffuse gliomas of adulthood are characterized by inexorable progression through treatment. Cancer recurrence in the context of therapy is by no means unique to gliomas. For many tumors residing outside the central nervous system (CNS), tissue-based analyses are routinely employed to document the molecular and cellular features of disease recurrence. Such interventions are inconsistently applied for gliomas, however, and lack rigorous standardization when they are. While many of the reasons underlying these discrepancies reflect pragmatic realities inherent to CNS disease, the suboptimal employment of histological and molecular assessment at recurrence nevertheless represents a missed opportunity to proactively guide patient management and increase knowledge. Herein, we address this quandary by pairing a succinct description of the histological, biological, and molecular characteristics of recurrent glioma with recommendations for how to better standardize and implement quality pathological assessment into patient management. We hope this review will prompt thoughtful revision of standard operating procedures to maximize the utility of glioma re-biopsy.

ctDNA-Based Liquid Biopsy of Cerebrospinal Fluid in Brain Cancer

The correct characterisation of central nervous system (CNS) malignancies is crucial for accurate diagnosis and prognosis and also the identification of actionable genomic alterations that can guide the therapeutic strategy. Surgical biopsies are performed to characterise the tumour; however, these procedures are invasive and are not always feasible for all patients. Moreover, they only provide a static snapshot and can miss tumour heterogeneity. Currently, monitoring of CNS cancer is performed by conventional imaging techniques and, in some cases, cytology analysis of the cerebrospinal fluid (CSF); however, these techniques have limited sensitivity. To overcome these limitations, a liquid biopsy of the CSF can be used to obtain information about the tumour in a less invasive manner. The CSF is a source of cell-free circulating tumour DNA (ctDNA), and the analysis of this biomarker can characterise and monitor brain cancer. Recent studies have shown that ctDNA is more abundant in the CSF than plasma for CNS malignancies and that it can be sequenced to reveal tumour heterogeneity and provide diagnostic and prognostic information. Furthermore, analysis of longitudinal samples can aid patient monitoring by detecting residual disease or even tracking tumour evolution at relapse and, therefore, tailoring the therapeutic strategy. In this review, we provide an overview of the potential clinical applications of the analysis of CSF ctDNA and the challenges that need to be overcome in order to translate research findings into a tool for clinical practice.

Rapid Autopsy Programs and Research Support: The Pre– and Post–COVID-19 Environments

Each rapid autopsy is a powerful opportunity to supply multiple researchers with many valuable tissue specimens at the same time. Since the beginning of the development of rapid autopsy, the overriding organizing principle for all rapid autopsy programs has been that the samples or organs must be removed and processed as rapidly as possible. To accomplish this, some rapid autopsy programs are focused on only 1 tumor type, whereas others accept patients demonstrating all tumor types and sometimes other diseases as well. Rapid autopsy programs are logistically complicated and labor-intensive structures; therefore, the key to their success is program flexibility and maintaining a multidisciplinary focus. The necessary collaborations in the complex relationships between clinicians and researchers can be broken down into a series of thought and action steps that must be understood, accepted, and practiced by all participants. A crucial part of the precase steps (prior to death) for a rapid autopsy is the study consenting process. It is extremely important that this individualized consent is obtained for postmortem specimens and that it is written in terms general enough to be used for patients with all types of diseases and for an appropriate range of future research uses. The advent of SARS-CoV-2/COVID-19 (severe acute respiratory syndrome coronavirus 2/coronavirus disease 2019) has presented new challenges and opportunities to the field of autopsy pathology. Guidelines and practice had to be created and adapted to protect physicians and staff while maximizing diagnostic yield. However, any autopsy performed on a patient dying of or with COVID-19 represents a unique opportunity to contribute to understanding the disease mechanisms and to improve death certification, thus assisting in both clinical care and the development of health public policy.

Rapid Autopsy Programs and Research Support: The Pre- and Post-COVID-19 Environments

Each rapid autopsy is a powerful opportunity to supply multiple researchers with many valuable tissue specimens at the same time. Since the beginning of the development of rapid autopsy, the overriding organizing principle for all RAPs has been that the samples or organs must be removed and processed as rapidly as possible. To accomplish this some rapid autopsy programs are focused just on one tumor type, while others accept patients demonstrating all tumor types and sometimes other diseases as well. RAPs are logistically complicated and labor-intensive structures, therefore, the key to their success is program flexibility and maintaining a multidisciplinary focus. The necessary collaborations in the complex relationships between clinicians and researchers can be broken down into a series of thought and action steps that must be understood, accepted, and practiced by all participants. A crucial part of the pre-case steps (prior to death) for a rapid autopsy is the study consenting process. It is extremely important that this individualized consent is obtained for postmortem specimens and that it is written in general enough terms to be used for patients with all types of diseases and for an appropriate range of future research uses. The advent of Sars-CoV-2/COVID-19 has presented new challenges and opportunities to the field of autopsy pathology. Guidelines and practice had to be created and adapted to protect physicians and staff while maximizing diagnostic yield. However, any autopsy performed on a patient dying of or with COVID-19 represents a unique opportunity to contribute to understanding of disease mechanisms and to improve death certification, thus assisting in both clinical care and the development of health public policy.

Overcoming barriers to establishing autopsy procurement programs in pediatric patients with central nervous system tumors: a call to develop regional centers

BACKGROUND

While autopsy-repository programs with a variety of pediatric central nervous system (CNS) tumor types are a critical resource for preclinical neuro-oncology research, few exist and there is no published guidance on how to develop one. The goal of this prospective Pediatric Brain Tumor Repository (PBTR) study was to develop such a program at Cincinnati Children's Hospital Medical Center (CCHMC) and then publish the quantitative and experiential data as a guide to support the development of similar programs.

METHODS

Protocols and infrastructure were established-to educate oncologists and families, establish eligibility, obtain consent, address pre- and post-autopsy logistics (e.g., patient and tissue transportation), process and authenticate tissue samples, and collect and analyze data.

RESULTS

Of the 129 pediatric CNS tumor patients at CCHMC who died between 2013 and 2018, 109 were eligible for our study. Of these, 74% (81 of 109) were approached for PBTR donation, and 68% (55 of 81) consented. In the final year of the study, approach and consent rates were 93% and 85%, respectively. Median time from death to autopsy (postmortem interval, PMI) was 10 h (range, 1.5-30). In the outpatient setting, PMI increased with distance (from the hospice/home where the patient died to CCHMC). In all patients, PMI appeared to be lower, when consent was obtained more than 24 h before death.

CONCLUSIONS

Procurement of autopsy specimens need not be a barrier in neuro-oncology research. Regional centers, strict timing-of-consent, patient education, and dedicated staff are all needed to minimize PMI and, thereby, increase the value of the procured tissue for an array of basic and translational research applications.

Parents' experiences of postmortem tumor donation for high-grade gliomas: benefits and suggested improvements

BACKGROUND

Pediatric high-grade glioma is a devastating diagnosis. There has been no improvement in outcomes for several decades, with few children surviving 2 years postdiagnosis. Research progress has been hampered by a lack of tumor samples, which can be used to develop and test novel therapies. Postmortem tumor donations are therefore a valuable opportunity to collect tissue. In this study, we explored Australian parents' experiences of donating their child's tumor for research after their child had died.

METHODS

We collected qualitative data from 11 bereaved parents who consented to donate samples of their child's high-grade glioma for research postmortem. We asked parents about their perceived benefits/burdens of the autopsy, recommendations for improving consent discussions, and decision regret.

RESULTS

Parents hoped that their donation would help to find a cure for future children with high-grade glioma. They described feeling comforted knowing that their child's suffering may help others. Some parents also felt that the donation would help them better understand their child's tumor. Although some parents described discomfort about procedures leading up to the autopsy, parents reported minimal regret regarding their decision to donate their child's tumor. Parents provided recommendations to improve consent discussions, such as providing more information about the autopsy logistics and why the donation was needed.

CONCLUSION

Parents consented to autopsy for altruistic reasons, although donation may also assist parents in their grieving. There is a strong need to improve access to tumor donations for any family who wishes to donate.

Convection Enhanced Delivery for Diffuse Intrinsic Pontine Glioma: Review of a Single Institution Experience

Diffuse intrinsic pontine gliomas (DIPGs) are a pontine subtype of diffuse midline gliomas (DMGs), primary central nervous system (CNS) tumors of childhood that carry a terrible prognosis. Because of the highly infiltrative growth pattern and the anatomical position, cytoreductive surgery is not an option. An initial response to radiation therapy is invariably followed by recurrence; mortality occurs approximately 11 months after diagnosis. The development of novel therapeutics with great preclinical promise has been hindered by the tightly regulated blood-brain barrier (BBB), which segregates the tumor comportment from the systemic circulation. One possible solution to this obstacle is the use of convection enhanced delivery (CED), a local delivery strategy that bypasses the BBB by direct infusion into the tumor through a small caliber cannula. We have recently shown CED to be safe in children with DIPG (NCT01502917). In this review, we discuss our experience with CED, its advantages, and technical advancements that are occurring in the field. We also highlight hurdles that will likely need to be overcome in demonstrating clinical benefit with this therapeutic strategy.

Harmonization of postmortem donations for pediatric brain tumors and molecular characterization of diffuse midline gliomas

Children diagnosed with brain tumors have the lowest overall survival of all pediatric cancers. Recent molecular studies have resulted in the discovery of recurrent driver mutations in many pediatric brain tumors. However, despite these molecular advances, the clinical outcomes of high grade tumors, including H3K27M diffuse midline glioma (H3K27M DMG), remain poor. To address the paucity of tissue for biological studies, we have established a comprehensive protocol for the coordination and processing of donated specimens at postmortem. Since 2010, 60 postmortem pediatric brain tumor donations from 26 institutions were coordinated and collected. Patient derived xenograft models and cell cultures were successfully created (76% and 44% of attempts respectively), irrespective of postmortem processing time. Histological analysis of mid-sagittal whole brain sections revealed evidence of treatment response, immune cell infiltration and the migratory path of infiltrating H3K27M DMG cells into other midline structures and cerebral lobes. Sequencing of primary and disseminated tumors confirmed the presence of oncogenic driver mutations and their obligate partners. Our findings highlight the importance of postmortem tissue donations as an invaluable resource to accelerate research, potentially leading to improved outcomes for children with aggressive brain tumors.

Differential Expression of Wilms' Tumor Protein in Diffuse Intrinsic Pontine Glioma

Diffuse intrinsic pontine gliomas (DIPGs) are deadly tumors comprising 10%–15% of all childhood CNS cancers. Standard treatment is considered palliative and prognosis is near universal mortality. DIPGs have been classified into genomic subtypes based on histone variants with the lysine to methionine mutation on position 27 of histone tails (K27M). Given the increasing promise of immunotherapy, there have been ongoing efforts to identify tumor-specific antigens to serve as immunologic targets. We evaluated a large cohort of CNS specimens for Wilms’ tumor protein (WT1) expression. These specimens include primary pediatric CNS tumors (n = 38 midline gliomas and n = 3 non-midline gliomas; n = 23 DIPG, n = 10 low-grade gliomas, n = 8 high-grade gliomas), and DIPG primary cells. Here, we report the validation of WT1 as a tumor-associated antigen in DIPGs. We further report that WT1 expression is significantly correlated with specific oncohistone variants, with the highest expression detected in the H3.3K27M subgroup. WT1 expression was absent in all control specimens (n = 21). Western blot assays using DIPG primary cells (n = 6) showed a trend of higher WT1 expression in H3.3K27M cells when compared with H3.1 K27M cells and H3 wildtype cells. Our data are the first indication of the association between WT1 and DIPG, with specific upregulation in those harboring oncohistone H3.3K27M.

Clinical trials using molecular stratification of pediatric brain tumors

Brain cancer is now the leading cause of cancer death in children and adolescents, surpassing leukemia. The heterogeneity and invasiveness of pediatric brain tumors have historically made them difficult to treat. Although surgical intervention and standard of care therapies such as radiation and chemotherapy have improved the outlook for those affected, results are often transient and lend themselves to tumor recurrence or resistance. There also still exists a subset of brain tumors which remain unresponsive to treatment altogether. Therefore, there is great need for new therapeutic approaches. With the recent advent of molecularly-driven technologies, many of these complex tumors can now be classified by integrating molecular profiling data with clinical information such as demographics and outcomes. This new knowledge has allowed for the molecular stratification of pediatric brain tumors into distinct subgroups and the identification of molecular targets, which is changing how these children are treated, namely in the setting of clinical trials. Notable examples include reduced doses of radiation and chemotherapy in the wingless-activated subgroup of medulloblastoma, which has a favorable prognosis, and novel experimental drugs targeting BRAF alterations in low-grade gliomas and dopamine receptors in high-grade gliomas. In this review, we highlight several key previous and ongoing clinical trials that utilize molecular stratifications and targets for the treatment of pediatric brain tumors.

Pediatric diffuse intrinsic pontine glioma: where do we stand?

Pediatric diffuse intrinsic pontine glioma (DIPG) represents approximately 20% of all pediatric CNS tumors. However, disease outcomes are dismal with a median survival of less than 1 year and a 2-year overall survival rate of less than 10%. Despite extensive efforts to improve survival outcomes, progress towards clinical improvement has been largely stagnant throughout the last 4 decades. Focal radiotherapy remains the standard of care with no promising single-agent alternatives and no evidence for improvement with the addition of a long list of systemic therapies. A better understanding of the biology of DIPG, though not easy due to obstacles in obtaining pathological material to study, is promising for the development of specific individualized treatment for this fatal disease. Recent studies have found epigenetic mutations to be successful predictors and prognostic factors for developing future management policies. The aim of this review is to give a global overview about the epidemiology, diagnosis, and treatment of DIPG. We further examine the controversial biopsy and autopsy issue that is unique to DIPG and assess the subsequent impact this issue has on the research efforts and clinical management of DIPG.

Increasing value of autopsies in patients with brain tumors in the molecular era

BACKGROUND

Pediatric brain tumors are associated with high morbidity and mortality, in part due to insufficient understanding of tumor biology. With limited tissue allocation for research from surgical specimens, a key barrier to improving biological understanding, brain tumor autopsies have become an increasingly valuable resource. This study reviews the brain tumor autopsy practice at our institution and describes specific emerging research utilization patterns beyond the clinical autopsy report.

METHODS

We performed a retrospective analysis of brain tumor autopsies at Boston Children's Hospital (BCH) between 2007 and 2017 and reviewed their consents, neuropathology reports and final diagnoses. We reviewed the method of tissue triaging for research consented autopsies (bioregistry, frozen and fresh tissue) and documented their specific uses.

RESULTS

Ninety-six deaths at BCH were due to brain tumors; 56 autopsies were performed (58.3%), of which 49 (87.5%) were consented for research. Tumor mapping was performed on all cases and tissue was allocated for DNA- and RNA-based sequencing studies (published and ongoing). Three tissue allocations with a postmortem interval of 8 h or less resulted in successful cell lines. Tissue from 14 autopsies was contributed to the National DIPG Registry.

CONCLUSION

Our institutional pediatric brain tumor autopsy clinical experience demonstrates the increased utility and wide utilization of autopsy-derived tissue for multiple types of research. These results support the increased efforts to obtain research consent for brain tumor autopsy and active collection of unfixed autopsy material in the molecular era.

A pilot precision medicine trial for children with diffuse intrinsic pontine glioma-PNOC003: A report from the Pacific Pediatric Neuro-Oncology Consortium

This clinical trial evaluated whether whole exome sequencing (WES) and RNA sequencing (RNAseq) of paired normal and tumor tissues could be incorporated into a personalized treatment plan for newly diagnosed patients (<25 years of age) with diffuse intrinsic pontine glioma (DIPG). Additionally, whole genome sequencing (WGS) was compared to WES to determine if WGS would further inform treatment decisions, and whether circulating tumor DNA (ctDNA) could detect the H3K27M mutation to allow assessment of therapy response. Patients were selected across three Pacific Pediatric Neuro-Oncology Consortium member institutions between September 2014 and January 2016. WES and RNAseq were performed at diagnosis and recurrence when possible in a CLIA-certified laboratory. Patient-derived cell line development was attempted for each subject. Collection of blood for ctDNA was done prior to treatment and with each MRI. A specialized tumor board generated a treatment recommendation including up to four FDA-approved agents based upon the genomic alterations detected. A treatment plan was successfully issued within 21 business days from tissue collection for all 15 subjects, with 14 of the 15 subjects fulfilling the feasibility criteria. WGS results did not significantly deviate from WES-based therapy recommendations; however, WGS data provided further insight into tumor evolution and fidelity of patient-derived cell models. Detection of the H3F3A or HIST1H3B K27M (H3K27M) mutation using ctDNA was successful in 92% of H3K27M mutant cases. A personalized treatment recommendation for DIPG can be rendered within a multicenter setting using comprehensive next-generation sequencing technology in a clinically relevant timeframe.

Current Murine Models and New Developments in H3K27M Diffuse Midline Gliomas

Diffuse Midline Gliomas with Histone 3-Lysine-27-Methionine (H3K27M) mutation constitute the majority of Diffuse Intrinsic Pontine Glioma (DIPG), which is the most aggressive form of pediatric glioma with a dire prognosis. DIPG are lethal tumors found in younger children with a median survival <1 year from diagnosis. Discovery of the characteristic H3K27M mutations offers opportunity and hope for development of targeted therapies for this deadly disease. The H3K27M mutation, likely through epigenetic alterations in specific H3 lysine trimethylation levels and subsequent gene expression, plays a significant role in pathogenesis of DIPG. Animal models accurately depicting molecular characteristics of H3K27M DIPG are important to elucidate underlying pathologic events and for preclinical drug evaluation. Here we review the past and present DIPG models and describe our efforts developing patient derived cell lines and xenografts from pretreated surgical specimens. Pre-treated surgical samples retain the characteristic genomic and phenotypic hallmarks of DIPG and establish orthotopic tumors in the mouse brainstem that recapitulate radiographic and morphological features of the original human DIPG tumor. These models that contain the H3K27M mutation constitute a valuable tool to further study this devastating disease and ultimately may uncover novel therapeutic vulnerabilities.

International experience in the development of patient-derived xenograft models of diffuse intrinsic pontine glioma

PURPOSE

Diffuse intrinsic pontine glioma is the most aggressive form of high grade glioma in children with no effective therapies. There have been no improvements in survival in part due poor understanding of underlying biology, and lack of representative in vitro and in vivo models. Recently, it has been found feasible to use both biopsy and autopsy tumors to generate cultures and xenograft models.

METHODS

To further model development, we evaluated the collective international experience from 8 collaborating centers to develop DIPG pre-clinical models from patient-derived autopsies and biopsies. Univariate and multivariate analysis was performed to determine key factors associated with the success of in vitro and in vivo PDX development.

RESULTS

In vitro cultures were successfully established from 57% of samples (84.2% of biopsies and 38.2% of autopsies). Samples transferred in DMEM media were more likely to establish successful culture than those transported in Hibernate A. In vitro cultures were more successful from biopsies (84.2%) compared with autopsies (38.2%) and as monolayer on laminin-coated plates than as neurospheres. Primary cultures successfully established from autopsy samples were more likely to engraft in animal models than cultures established from biopsies (86.7% vs. 47.4%). Collectively, tumor engraftment was more successful when DIPG samples were directly implanted in mice (68%), rather than after culturing (40.7%).

CONCLUSION

This multi-center study provides valuable information on the success rate of establishing patient-derived pre-clinical models of DIPG. The results can lead to further optimization of DIPG model development and ultimately assist in the investigation of new therapies for this aggressive pediatric brain tumor.

Clinically Relevant and Minimally Invasive Tumor Surveillance of Pediatric Diffuse Midline Gliomas Using Patient-Derived Liquid Biopsy

PURPOSE

Pediatric diffuse midline glioma (DMG) are highly malignant tumors with poor clinical outcomes. Over 70% of patients with DMG harbor the histone 3 p.K27M (H3K27M) mutation, which correlates with a poorer clinical outcome, and is also used as a criterion for enrollment in clinical trials. Because complete surgical resection of DMG is not an option, biopsy at presentation is feasible, but rebiopsy at time of progression is rare. While imaging and clinical-based disease monitoring is the standard of care, molecular-based longitudinal characterization of these tumors is almost nonexistent. To overcome these hurdles, we examined whether liquid biopsy allows measurement of disease response to precision therapy.

EXPERIMENTAL DESIGN

We established a sensitive and specific methodology that detects major driver mutations associated with pediatric DMGs using droplet digital PCR (n = 48 subjects, n = 110 specimens). Quantification of circulating tumor DNA (ctDNA) for H3K27M was used for longitudinal assessment of disease response compared with centrally reviewed MRI data.

RESULTS

H3K27M was identified in cerebrospinal fluid (CSF) and plasma in 88% of patients with DMG, with CSF being the most enriched for ctDNA. We demonstrated the feasibility of multiplexing for detection of H3K27M, and additional driver mutations in patient's tumor and matched CSF, maximizing the utility of a single source of liquid biome. A significant decrease in H3K27M plasma ctDNA agreed with MRI assessment of tumor response to radiotherapy in 83% (10/12) of patients.

CONCLUSIONS

Our liquid biopsy approach provides a molecularly based tool for tumor characterization, and is the first to indicate clinical utility of ctDNA for longitudinal surveillance of DMGs.

Diffuse Intrinsic Pontine Glioma : Clinical Features, Molecular Genetics, and Novel Targeted Therapeutics

Diffuse intrinsic pontine glioma (DIPG) is a deadly paediatric brain cancer. Transient response to radiation, ineffective chemotherapeutic agents and aggressive biology result in rapid progression of symptoms and a dismal prognosis. Increased availability of tumour tissue has enabled the identification of histone gene aberrations, genetic driver mutations and methylation changes, which have resulted in molecular and phenotypic subgrouping. However, many of the underlying mechanisms of DIPG oncogenesis remain unexplained. It is hoped that more representative in vitro and preclinical models–using both xenografted material and genetically engineered mice–will enable the development of novel chemotherapeutic agents and strategies for targeted drug delivery. This review provides a clinical overview of DIPG, the barriers to progress in developing effective treatment, updates on drug development and preclinical models, and an introduction to new technologies aimed at enhancing drug delivery.

Rapid autopsy of a patient with recurrent anaplastic ependymoma

ABSTRACTObjective:Our aim was to outline a procedure for obtaining a rapid autopsy in order to collect high-quality postmortem tissue for genomic analysis.

METHODS

This report details a bi-institutional collaborative effort to coordinate a rapid autopsy for a pediatric patient who had died at home. We discuss the scientific rationale for offering a rapid autopsy to caregivers of pediatric patients as well as parental perspectives on broaching the subject of autopsy. We then review the logistics and coordination involved with planning a rapid autopsy and the sequence of events needed to maximize tissue quality.

RESULTS

We report the successful coordination of a rapid autopsy for a patient who died in a hospice setting at her out-of-state home. The time interval from death to the start of the rapid autopsy procedure was 4.5 hours, despite the logistical considerations demanded by the location of the patient. Tumor aliquots and nonneoplastic tissues were successfully snap frozen for downstream genomic studies.

SIGNIFICANCE OF RESULTS

Physicians should consider trialing a rapid autopsy program at their institution that could be offered to caregivers of pediatric patients. This case report offers a framework to help clinicians develop their own rapid autopsy programs as well as guidelines to help streamline this process for appropriate candidates going forward.

Deceptive morphologic and epigenetic heterogeneity in diffuse intrinsic pontine glioma

Historically, the diagnosis of diffuse intrinsic pontine glioma (DIPG) was based on typical imaging findings and clinical characteristics instead of pathology. However, the discovery of mutations in histone H3 variants, and the availability of tumor material for molecular analysis, has led to a paradigm shift in DIPG research and clinical practice. Using data from whole-brain autopsies in a series of nine DIPG patients with known histone mutational status, we here aim to review histopathological characteristics with special focus on intratumoral heterogeneity (ITH) and histone 3 K27 trimethylation (H3 K27me3). All DIPGs showed marked histologic ITH, with 56% even showing focal areas resembling a WHO grade I phenotype. As expected, H3 K27me3 immunoreactivity was lost in the tumors that were H3 K27M-mutated (seven patients; 67% H3.3, 11% H3.1). Strikingly, the H3K27 wildtype tumors (two patients; 22%) also contained H3 K27me3-immunonegative areas. Our study underscores the importance of the choice of the biopsy site, as ITH in DIPGs could theoretically lead to erroneous histological diagnoses with small biopsies. New in this respect is our finding that a substantial number of otherwise typical DIPGs has areas resembling WHO grade I tumors (esp. pilocytic astrocytoma, subependymoma). Furthermore, our study shows that negative H3 K27me3 immunohistochemistry in a DIPG does not imply a H3 K27-mutant tumor.

Next-Generation Rapid Autopsies Enable Tumor Evolution Tracking and Generation of Preclinical Models

PURPOSE

Patients with cancer who graciously consent for autopsy represent an invaluable resource for the study of cancer biology. To advance the study of tumor evolution, metastases, and resistance to treatment, we developed a next-generation rapid autopsy program integrated within a broader precision medicine clinical trial that interrogates pre- and postmortem tissue samples for patients of all ages and cancer types.

MATERIALS AND METHODS

One hundred twenty-three (22%) of 554 patients who consented to the clinical trial also consented for rapid autopsy. This report comprises the first 15 autopsies, including patients with metastatic carcinoma (n = 10), melanoma (n = 1), and glioma (n = 4). Whole-exome sequencing (WES) was performed on frozen autopsy tumor samples from multiple anatomic sites and on non-neoplastic tissue. RNA sequencing (RNA-Seq) was performed on a subset of frozen samples. Tissue was also used for the development of preclinical models, including tumor organoids and patient-derived xenografts.

RESULTS

Three hundred forty-six frozen samples were procured in total. WES was performed on 113 samples and RNA-Seq on 72 samples. Successful cell strain, tumor organoid, and/or patient-derived xenograft development was achieved in four samples, including an inoperable pediatric glioma. WES data were used to assess clonal evolution and molecular heterogeneity of tumors in individual patients. Mutational profiles of primary tumors and metastases yielded candidate mediators of metastatic spread and organotropism including CUL9 and PIGM in metastatic ependymoma and ANKRD52 in metastatic melanoma to the lung. RNA-Seq data identified novel gene fusion candidates.

CONCLUSION

A next-generation sequencing-based autopsy program in conjunction with a pre-mortem precision medicine pipeline for diverse tumors affords a valuable window into clonal evolution, metastasis, and alterations underlying treatment. Moreover, such an autopsy program yields robust preclinical models of disease.

The international diffuse intrinsic pontine glioma registry: an infrastructure to accelerate collaborative research for an orphan disease

Diffuse intrinsic pontine glioma (DIPG), a rare, often fatal childhood brain tumor, remains a major therapeutic challenge. In 2012, investigators, funded by the DIPG Collaborative (a philanthropic partnership among 29 private foundations), launched the International DIPG Registry (IDIPGR) to advance understanding of DIPG. Comprised of comprehensive deidentified but linked clinical, imaging, histopathological, and genomic repositories, the IDIPGR uses standardized case report forms for uniform data collection; serial imaging and histopathology are centrally reviewed by IDIPGR neuro-radiologists and neuro-pathologists, respectively. Tissue and genomic data, and cell cultures derived from autopsies coordinated by the IDIPGR are available to investigators for studies approved by the Scientific Advisory Committee. From April 2012 to December 2016, 670 patients diagnosed with DIPG have been enrolled from 55 participating institutions in the US, Canada, Australia and New Zealand. The radiology repository contains 3558 studies from 448 patients. The pathology repository contains tissue on 81 patients with another 98 samples available for submission. Fresh DIPG tissue from seven autopsies has been sent to investigators to develop primary cell cultures. The bioinformatics repository contains next-generation sequencing data on 66 tumors. Nine projects using data/tissue from the IDIPGR by 13 principle investigators from around the world are now underway. The IDIPGR, a successful alliance among philanthropic agencies and investigators, has developed and maintained a highly collaborative, hypothesis-driven research infrastructure for interdisciplinary and translational projects in DIPG to improve diagnosis, response assessment, treatment and outcome for patients.

New in vivo avatars of diffuse intrinsic pontine gliomas (DIPG) from stereotactic biopsies performed at diagnosis

Diffuse Instrinsic Pontine Glioma is the most aggressive form of High Grade Gliomas in children. The lack of biological material and the absence of relevant models have hampered the development of new therapeutics. Their extensive infiltration of the brainstem renders any surgical resection impossible and until recently biopsies were considered not informative enough and therefore not recommended. Thus, most models were derived from autopsy material. We aimed to develop relevant in vivo DIPG models that mimic this specific disease and its molecular diversity from tumor material obtained at diagnosis. Eight patient-derived orthotopic xenograft models were obtained after direct stereotactic injection of a mixed cell suspension containing tumor cells and stromal cells in the brainstem or thalamus of nude mice and serially passaged thereafter. In parallel, we developed 6 cell-derived xenograft models after orthotopic injection of tumor-initiating cells cultured from stereotactic biopsies. Cells were modified to express luciferase to enable longitudinal tumor growth monitoring, and fluorescent reporter proteins to trace the tumor cells in the brain.

These models do not form a tumor mass, they are invasive, show the H3K27 trimethylation loss in vivo and the tumor type diversity observed in patients in terms of histone H3 mutations and lineage markers. Histological and MRI features at 11.7 Tesla show similarities with treatment naïve human DIPG, and in this respect, both direct and indirect orthotopic xenograft looked alike. These DIPG models will therefore constitute valuable tools for evaluating new therapeutic approaches in this devastating disease.

Gliomatosis cerebri: A consensus summary report from the First International Gliomatosis cerebri Group Meeting, March 26-27, 2015, Paris, France

Gliomatosis cerebri (GC) is a universally fatal extensive and diffuse infiltration of brain parenchyma by a glial tumor. Many aspects of this phenomenon remain unknown. The First International Gliomatosis cerebri Group Meeting had the following goals: refine the clinical and radiologic diagnostic criteria for GC, suggest appropriate diagnostic procedures, standardize tissue manipulation for histologic and molecular characterization, and prioritize relevant preclinical projects. Also, general treatment recommendations were outlined for the pediatric population. Importantly, this meeting was the starting point for meaningful collaborative international research projects. This review is a consensus summary of discussions shared and conclusions derived from this meeting.

Spatial and temporal homogeneity of driver mutations in diffuse intrinsic pontine glioma

Diffuse Intrinsic Pontine Gliomas (DIPGs) are deadly paediatric brain tumours where needle biopsies help guide diagnosis and targeted therapies. To address spatial heterogeneity, here we analyse 134 specimens from various neuroanatomical structures of whole autopsy brains from nine DIPG patients. Evolutionary reconstruction indicates histone 3 (H3) K27M--including H3.2K27M--mutations potentially arise first and are invariably associated with specific, high-fidelity obligate partners throughout the tumour and its spread, from diagnosis to end-stage disease, suggesting mutual need for tumorigenesis. These H3K27M ubiquitously-associated mutations involve alterations in TP53 cell-cycle (TP53/PPM1D) or specific growth factor pathways (ACVR1/PIK3R1). Later oncogenic alterations arise in sub-clones and often affect the PI3K pathway. Our findings are consistent with early tumour spread outside the brainstem including the cerebrum. The spatial and temporal homogeneity of main driver mutations in DIPG implies they will be captured by limited biopsies and emphasizes the need to develop therapies specifically targeting obligate oncohistone partnerships.

The emerging role of NG2 in pediatric diffuse intrinsic pontine glioma

Diffuse intrinsic pontine gliomas (DIPGs) have a dismal prognosis and are poorly understood brain cancers. Receptor tyrosine kinases stabilized by neuron-glial antigen 2 (NG2) protein are known to induce gliomagenesis. Here, we investigated NG2 expression in a cohort of DIPG specimens (n= 50). We demonstrate NG2 expression in the majority of DIPG specimens tested and determine that tumors harboring histone 3.3 mutation express the highest NG2 levels. We further demonstrate that microRNA 129-2 (miR129-2) is downregulated and hypermethylated in human DIPGs, resulting in the increased expression of NG2. Treatment with 5-Azacytidine, a methyltransferase inhibitor, results in NG2 downregulation in DIPG primary tumor cells in vitro. NG2 expression is altered (symmetric segregation) in mitotic human DIPG and mouse tumor cells. These mitotic cells co-express oligodendrocyte (Olig2) and astrocyte (glial fibrillary acidic protein, GFAP) markers, indicating lack of terminal differentiation. NG2 knockdown retards cellular migration in vitro, while NG2 expressing neurospheres are highly tumorigenic in vivo, resulting in rapid growth of pontine tumors. NG2 expression is targetable in vivo using miR129-2 indicating a potential avenue for therapeutic interventions. This data implicates NG2 as a molecule of interest in DIPGs especially those with H3.3 mutation.

Spatial genomic heterogeneity in diffuse intrinsic pontine and midline high-grade glioma: implications for diagnostic biopsy and targeted therapeutics

Introduction

Diffuse intrinsic pontine glioma (DIPG) and midline high-grade glioma (mHGG) are lethal childhood brain tumors. Spatial genomic heterogeneity has been well-described in adult HGG but has not been comprehensively characterized in pediatric HGG. We performed whole exome sequencing on 38-matched primary, contiguous, and metastatic tumor sites from eight children with DIPG (n = 7) or mHGG (n = 1) collected using a unique MRI-guided autopsy protocol. Validation was performed using Sanger sequencing, Droplet Digital polymerase-chain reaction, immunohistochemistry, and fluorescent in-situ hybridization.

Results

Median age at diagnosis was 6.1 years (range: 2.9–23.3 years). Median overall survival was 13.2 months (range: 11.2–32.2 months). Contiguous tumor infiltration and distant metastases were observed in seven and six patients, respectively, including leptomeningeal dissemination in three DIPGs. Histopathological heterogeneity was evident in seven patients, including intra-pontine heterogeneity in two DIPGs, ranging from World Health Organization grade II to IV astrocytoma. We found conservation of heterozygous K27M mutations in H3F3A (n = 4) or HIST1H3B (n = 3) across all primary, contiguous, and metastatic tumor sites in all DIPGs. ACVR1 (n = 2), PIK3CA (n = 2), FGFR1 (n = 2), and MET (n = 1) were also intra-tumorally conserved. ACVR1 was co-mutated with HIST1H3B (n = 2). In contrast, PDGFRA amplification and mutation were spatially heterogeneous, as were mutations in BCOR (n = 1), ATRX (n = 2), and MYC (n = 1). TP53 aberrations (n = 3 patients) varied by type and location between primary and metastatic tumors sites but were intra-tumorally conserved.

Conclusion

Spatial conservation of prognostically-relevant and therapeutically-targetable somatic mutations in DIPG and mHGG contrasts the significant heterogeneity of driver mutations seen in adult HGG and supports uniform implementation of diagnostic biopsy in DIPG and mHGG to classify molecular risk groups and guide therapeutic strategy.

Electronic supplementary material

The online version of this article (doi:10.1186/s40478-015-0269-0) contains supplementary material, which is available to authorized users.

Common mutations in ALK2/ACVR1, a multi-faceted receptor, have roles in distinct pediatric musculoskeletal and neural orphan disorders

Activin receptor-like kinase-2 (ALK2), the product of ACVR1, is a member of the type I bone morphogenetic protein (BMP) receptor family. ALK2 exerts key and non-redundant roles in numerous developmental processes, including the specification, growth and morphogenesis of endochondral skeletal elements. There is also strong evidence that BMP signaling plays important roles in determination, differentiation and function of neural cells and tissues. Here we focus on the intriguing discovery that common activating mutations in ALK2 occur in Fibrodysplasia Ossificans Progressiva (FOP) and Diffuse Intrinsic Pontine Gliomas (DIPGs), distinct pediatric disorders of significant severity that are associated with premature death. Pathogenesis and treatment remain elusive for both. We consider recent studies on the nature of the ACVR1 mutations, possible modes of action and targets, and plausible therapeutic measures. Comparisons of the diverse - but genetically interrelated - pathologies of FOP and DIPG will continue to be of major mutual benefit with broad biomedical and clinical relevance.

Disrupting NOTCH Slows Diffuse Intrinsic Pontine Glioma Growth, Enhances Radiation Sensitivity, and Shows Combinatorial Efficacy With Bromodomain Inhibition

NOTCH regulates stem cells during normal development and stemlike cells in cancer, but the roles of NOTCH in the lethal pediatric brain tumor diffuse intrinsic pontine glioma (DIPG) remain unknown. Because DIPGs express stem cell factors such as SOX2 and MYCN, we hypothesized that NOTCH activity would be critical for DIPG growth. We determined that primary DIPGs expressed high levels of NOTCH receptors, ligands, and downstream effectors. Treatment of the DIPG cell lines JHH-DIPG1 and SF7761 with the γ-secretase inhibitor MRK003 suppressed the level of the NOTCH effectors HES1, HES4, and HES5; inhibited DIPG growth by 75%; and caused a 3-fold induction of apoptosis. Short hairpin RNAs targeting the canonical NOTCH pathway caused similar effects. Pretreatment of DIPG cells with MRK003 suppressed clonogenic growth by more than 90% and enhanced the efficacy of radiation therapy. The high level of MYCN in DIPG led us to test sequential therapy with the bromodomain inhibitor JQ1 and MRK003, and we found that JQ1 and MRK003 inhibited DIPG growth and induced apoptosis. Together, these results suggest that dual targeting of NOTCH and MYCN in DIPG may be an effective therapeutic strategy in DIPG and that adding a γ-secretase inhibitor during radiation therapy may be efficacious initially or during reirradiation.

Clinicopathology of diffuse intrinsic pontine glioma and its redefined genomic and epigenomic landscape

Diffuse intrinsic pontine glioma (DIPG) is one of the most lethal pediatric central nervous system (CNS) cancers. Recently, a surge in molecular studies of DIPG has occurred, in large part due to the increased availability of tumor tissue through donation of post-mortem specimens. These new discoveries have established DIPGs as biologically distinct from adult gliomas, harboring unique genomic aberrations. Mutations in histone encoding genes are shown to be associated with >70% of DIPG cases. However, the exact molecular mechanisms of the tumorigenicity of these mutations remain elusive. Understanding the driving mutations and genomic landscape of DIPGs can now guide the development of targeted therapies for this incurable childhood cancer.