Biological material collection to advance translational research and treatment of children with CNS tumours: position paper from the SIOPE Brain Tumour Group

Neurosurgical treatment of pediatric brain tumors - results from a single center multidisciplinary setup

OBJECTIVE

The challenge of pediatric brain tumor surgery is given due to a relative low prevalence but high heterogeneity in age, localization, and pathology. Improvements of long-term overall survival rates were achieved during the past decades stressing the importance of a multidisciplinary decision process guided by a national treatment protocol. We reviewed the entire spectrum of pediatric brain tumor surgeries from the perspective of an interdisciplinary pediatric neuro-oncology center in Germany.

METHODS

Every patient who underwent brain tumor surgery from January 2010 to June 2017 in our Pediatric Neurosurgery department was retrospectively included and evaluated regarding the course of treatment. Perioperative data such as tumor localization, timing of surgery, extent of resection, neuropathological diagnosis, transfusion rates, oncologic and radiation therapy, and neurological follow-up including morbidity and mortality were evaluated.

RESULTS

Two hundred ninety-three pediatric brain tumor patients were applicable (age: 8.28 ± 5.62 years, 1.22:1.0 m:f). A total of 531 tumor surgical interventions was performed within these patients (457 tumor resections, 74 tumor biopsies; mean interventions per patient 1.8 ± 1.2). Due to a critical neurologic status, 32 operations (6%) were performed on the day of admission. In 65.2% of all cases, tumor were approached supratentorially. Most frequent diagnoses of the cases were glial tumors (47.8%) and embryonal tumors (17.6%). Preoperative planned extent of resection was achieved in 92.7%. Pre- and postoperative neurologic deficits resolved completely in 30.7%, whereas symptom regressed in 28.6% of surgical interventions. New postoperative neurologic deficit was observed in 10.7%, which resolved or improved in 80% of these cases during 30 days. The mortality rate was 1%.

CONCLUSION

We outlined the center perspective of a specialized pediatric neuro-oncological center describing the heterogeneous distribution of cases regarding age-related prevalence, tumor localization, and biology, which requires a high multidisciplinary expertise. The study contributes to define challenges in treating pediatric brain tumors and to develop quality indicators for pediatric neuro-oncological surgery. We assume that an adequate volume load of patients within a interdisciplinary infrastructure is warranted to aim for effective treatment and decent quality of life for the majority of long-term surviving pediatric tumor patients.

Beijing Children's Hospital guidelines on the design and conduction of the first standardized database for medulloblastoma

Medulloblastoma (MB) is one of the most common malignant childhood brain tumors (WHO grade IV). Its high degree of malignancy leads to an unsatisfactory prognosis, requiring more precise and personalized treatment in the near future. Multi-omics and artificial intelligence have been playing a significant role in precise medical research, but their implementation needs a large amount of clinical information and biomaterials. For these reasons, it is urgent for current MB researchers to establish a large sample-size database of MB that contains complete clinical data and sufficient biomaterials such as blood, cerebrospinal fluid (CSF), cancer tissue, and urine. Unfortunately, there are few biobanks of pediatric central nervous system (CNS) tumors throughout the world for limited specimens, scarce funds, different standards collecting methods and et cl. Even though, China falls behind western countries in this area. The present research set up a standard workflow to construct the Beijing Children's Hospital Medulloblastoma (BCH-MB) biobank. Clinical data from children with MB and for collecting and storing biomaterials, along with regular follow-up has been collected and recorded in this database. In the future, the BCH-MB biobank could make it possible to validate the promising biomarkers already identified, discover unrevealed MB biomarkers, develop novel therapies, and establish personalized prognostic models for children with MB upon the support of its sufficient data and biomaterials, laying the foundation for individualized therapies of children with MB.

Relapsed Medulloblastoma in Pre-Irradiated Patients: Current Practice for Diagnostics and Treatment

Relapsed medulloblastoma (rMB) accounts for a considerable, and disproportionate amount of childhood cancer deaths. Recent advances have gone someway to characterising disease biology at relapse including second malignancies that often cannot be distinguished from relapse on imaging alone. Furthermore, there are now multiple international early-phase trials exploring drug-target matches across a range of high-risk/relapsed paediatric tumours. Despite these advances, treatment at relapse in pre-irradiated patients is typically non-curative and focuses on providing life-prolonging and symptom-modifying care that is tailored to the needs and wishes of the individual and their family. Here, we describe the current understanding of prognostic factors at disease relapse such as principal molecular group, adverse molecular biology, and timing of relapse. We provide an overview of the clinical diagnostic process including signs and symptoms, staging investigations, and molecular pathology, followed by a summary of treatment modalities and considerations. Finally, we summarise future directions to progress understanding of treatment resistance and the biological mechanisms underpinning early therapy-refractory and relapsed disease. These initiatives include development of comprehensive and collaborative molecular profiling approaches at relapse, liquid biopsies such as cerebrospinal fluid (CSF) as a biomarker of minimal residual disease (MRD), modelling strategies, and the use of primary tumour material for real-time drug screening approaches.

SIOP PNET5 MB Trial: History and Concept of a Molecularly Stratified Clinical Trial of Risk-Adapted Therapies for Standard-Risk Medulloblastoma

BACKGROUND

SIOP PNET5 MB was initiated in 2014 as the first European trial using clinical, histological, and molecular parameters to stratify treatments for children and adolescents with standard-risk medulloblastoma.

METHODS

Stratification by upfront assessment of molecular parameters requires the timely submission of adequate tumour tissue. In the standard-risk phase-III cohort, defined by the absence of high-risk criteria (M0, R0), pathological (non-LCA), and molecular biomarkers (MYCN amplification in SHH-MB or MYC amplification), a randomized intensification by carboplatin concomitant with radiotherapy is investigated. In the LR stratum for localized WNT-activated medulloblastoma and age <16 years, a reduction of craniospinal radiotherapy dose to 18 Gy and a reduced maintenance chemotherapy are investigated. Two additional strata (WNT-HR, SHH-TP53) were implemented during the trial.

RESULTS

SIOP PNET5 MB is actively recruiting. The availability of adequate tumour tissue for upfront real-time biological assessments to assess inclusion criteria has proven feasible.

CONCLUSION

SIOP PNET5 MB has demonstrated that implementation of biological parameters for stratification is feasible in a prospective multicentre setting, and may improve risk-adapted treatment. Comprehensive research studies may allow assessment of additional parameters, e.g., novel medulloblastoma subtypes, and identification and validation of biomarkers for the further refinement of risk-adapted treatment in the future.

Current treatments of medulloblastoma

PURPOSE OF REVIEW

The biological knowledge and the new biopathological classification of medulloblastoma subtypes have dramatically changed the therapeutic indications, taking into account not only age and staging but also biopathological risk criteria. This review covers the multidisciplinary approach including surgery, radiation oncology and medical treatments.

RECENT FINDINGS

The neurosurgical management of tumor-related hydrocephalus has been modified by the introduction of third ventriculostomy. The initial complete excision is no longer always the first choice, to preserve neurological function. The recent technical improvements of radiotherapy are also implemented to optimize outcome in terms of survival as well as quality of survival. The different medical treatments are adapted according to age and risk factors. The role of high-dose chemotherapy with autologous hematopoietic stem cell rescue has become larger in the high-risk situations.

SUMMARY

The rarity of the disease and the high-level of technicity of diagnosis, biopathological subtyping and treatments justifies the referral of these patients to highly specialized centers where all these techniques can be routinely applied, most often in the context of international prospective studies.

Biobanking of human gut organoids for translational research

The development of human organoid culture models has led to unprecedented opportunities to generate self-organizing, three-dimensional miniature organs that closely mimic in vivo conditions. The ability to expand, culture, and bank such organoids now provide researchers with the opportunity to generate next-generation living biobanks, which will substantially contribute to translational research in a wide range of areas, including drug discovery and testing, regenerative medicine as well as the development of a personalized treatment approach. However, compared to traditional tissue repositories, the generation of a living organoid biobank requires a much higher level of coordination, additional resources, and scientific expertise. In this short review, we discuss the opportunities and challenges associated with the generation of a living organoid biobank. Focusing on human intestinal organoids, we highlight some of the key aspects that need to be considered and provide an outlook for future development in this exciting field.

Follow-up evaluation of a web-based pediatric brain tumor board in Latin America

BACKGROUND

Since 2013, pediatric oncologists from Central and South America discuss neuro-oncology cases with experts from North America and Europe in a web-based "Latin American Tumor Board" (LATB). Here, we evaluate the feasibility of recommendations rendered by the Board.

METHODS

An electronic questionnaire was distributed to physicians who had received recommendations between October 2017 and October 2018. Physicians were asked regarding the feasibility of each recommendation given during the LATB discussion. Baseline case characteristics of all presented cases were obtained from anonymized minutes.

RESULTS

Of the 142 patients discussed, data on 103 patients from 15 countries were available, corresponding to 283 recommendations. Physicians followed 60% of diagnostic procedural recommendations and 69% of therapeutic recommendations. The most difficult recommendations to follow were genetic and molecular testing, pathology review, chemotherapy, surgery, and molecular targeted therapies. Histological diagnoses changed in eight of 18 cases in which a pathology review was undertaken. Fifty-four percent of the recommendations that could not be implemented were considered not feasible in the specific context of the patient, while 31% were not implemented due to a decision of the medical staff or the parents (15% not specified). However, 96% of respondents considered the recommendations useful.

CONCLUSION

Recommendations were frequently perceived as useful, and were applicable in the participating institutions. Nevertheless, limitations in availability of diagnostic procedures and treatment modalities affected the feasibility of some recommendations. Tele-oncology tumor boards offer physicians from low- and middle-income countries access to real-time, high-level subspecialist expertise and provide a valuable platform for worldwide information exchange.

Advanced molecular pathology for rare tumours: A national feasibility study and model for centralised medulloblastoma diagnostics

Aims

Application of advanced molecular pathology in rare tumours is hindered by low sample numbers, access to specialised expertise/technologies and tissue/assay QC and rapid reporting requirements. We assessed the feasibility of co‐ordinated real‐time centralised pathology review (CPR), encompassing molecular diagnostics and contemporary genomics (RNA‐seq/DNA methylation‐array).

Methods

This nationwide trial in medulloblastoma (<80 UK diagnoses/year) introduced a national reference centre (NRC) and assessed its performance and reporting to World Health Organisation standards. Paired frozen/formalin‐fixed, paraffin‐embedded tumour material were co‐submitted from 135 patients (16 referral centres).

Results

Complete CPR diagnostics were successful for 88% (120/135). Inadequate sampling was the most common cause of failure; biomaterials were typically suitable for methylation‐array (129/135, 94%), but frozen tissues commonly fell below RNA‐seq QC requirements (53/135, 39%). Late reporting was most often due to delayed submission. CPR assigned or altered histological variant (vs local diagnosis) for 40/135 tumours (30%). Benchmarking/QC of specific biomarker assays impacted test results; fluorescent in‐situ hybridisation most accurately identified high‐risk MYC/MYCN amplification (20/135, 15%), while combined methods (CTNNB1/chr6 status, methylation‐array subgrouping) best defined favourable‐risk WNT tumours (14/135; 10%). Engagement of a specialist pathologist panel was essential for consensus assessment of histological variants and immunohistochemistry. Overall, CPR altered clinical risk‐status for 29% of patients.

Conclusion

National real‐time CPR is feasible, delivering robust diagnostics to WHO criteria and assignment of clinical risk‐status, significantly altering clinical management. Recommendations and experience from our study are applicable to advanced molecular diagnostics systems, both local and centralised, across rare tumour types, enabling their application in biomarker‐driven routine diagnostics and clinical/research studies.

Clinical utility of circulating miR-371a-3p for the management of patients with intracranial malignant germ cell tumors

Background

The current biomarkers alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) have limited sensitivity/specificity for diagnosing malignant germ cell tumors (GCTs) and "marker-negative" patients require histological confirmation for diagnosis. However, GCTs at intracranial sites are surgically relatively inaccessible and biopsy carries risks. MicroRNAs from the miR-371~373 and miR-302/367 clusters are over-expressed in all malignant GCTs and, in particular, miR-371a-3p shows elevated serum levels at diagnosis for testicular disease.

Methods

Using our robust preamplified qRT-PCR methodology, we quantified miR-371a-3p levels in serum and cerebrospinal fluid (CSF) in a series of 4 representative clinical cases, 3 with intracranial malignant GCT and 1 with Langerhans cell histiocytosis (LCH), compared with appropriate control cases.

Results

Serum and/or CSF miR-371a-3p levels distinguished those with intracranial malignant GCTs from LCH and, if known in real time, could have helped clinical management. The benefits would have included (1) the only confirmatory evidence of an intracranial malignant GCT in 1 case, supporting clinical decision making; (2) early detection of intracranial malignant GCT in another, where an elevated CSF miR-371a-3p level preceded the histologically confirmed diagnosis by 2 years; and (3) confirmation of an intracranial malignant GCT relapse with an elevated serum miR-371a-3p level, where serum and CSF AFP and HCG levels were below thresholds for such a diagnosis.

Conclusions

This series highlights the potential for microRNA quantification to assist the noninvasive diagnosis, prognostication, and management for patients with intracranial malignant GCTs. Serum and CSF should be collected routinely as part of future studies to facilitate the extension of these findings to larger patient cohorts.

Biopsy in diffuse pontine gliomas: expert neurosurgeon opinion-a survey from the SIOPE brain tumor group

INTRODUCTION

The prognosis of diffuse intrinsic pontine glioma (DIPG) is poor. The role of biopsy in DIPG remains controversial since the diagnosis may be established with imaging alone. Recent advances in understanding molecular biology and targeting of brain tumors have created a renewed interest in biopsy for DIPG. The Neurosurgery Working Group (NWG) of the SIOP-Europe Brain Tumor Group (BTG) undertook a survey among international pediatric neurosurgeons to define their current perceptions and practice regarding DIPG biopsy.

METHODS

The NWG developed a 20-question survey which was emailed to neurosurgeons in the International Society for Pediatric Neurosurgery (ISPN). The questionnaire included questions on diagnosis, indications, and techniques for biopsy, clinical trials, and healthcare infrastructure.

RESULTS

The survey was sent to 202 neurosurgeons and 73 (36%) responded. Consensus of > 75% agreement was reached for 12/20 questions, which included (1) radiological diagnosis of DIPG is sufficient outside a trial, (2) clinical trial-based DIPG biopsy is justified if molecular targets are investigated and may be used for treatment, and (3) morbidity/mortality data must be collected to define the risk:benefit ratio. The remaining 8/20 questions proved controversial and failed to reach consensus.

CONCLUSIONS

Routine DIPG biopsy continues to be debated. Most neurosurgeons agreed that DIPG biopsy within a clinical trial should be supported, with the aims of defining the procedure risks, improving understanding of tumor biology, and evaluating new treatment targets. Careful family counseling and consent remain important.

Patient-Derived Orthotopic Xenograft Models of Pediatric Brain Tumors: In a Mature Phase or Still in Its Infancy?

In recent years, molecular profiling has led to the discovery of an increasing number of brain tumor subtypes, and associated therapeutic targets. These molecular features have been incorporated in the 2016 new World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS), which now distinguishes tumor subgroups not only histologically, but also based on molecular characteristics. Despite an improved diagnosis of (pediatric) tumors in the CNS however, the survival of children with malignant brain tumors still is far worse than for those suffering from other types of malignancies. Therefore, new treatments need to be developed, based on subgroup-specific genetic aberrations. Here, we provide an overview of the currently available orthotopic xenograft models for pediatric brain tumor subtypes as defined by the 2016 WHO classification, to facilitate the choice of appropriate animal models for the preclinical testing of novel treatment strategies, and to provide insight into the current gaps and challenges.

Translational genomics of malignant rhabdoid tumours: Current impact and future possibilities

Malignant Rhabdoid Tumours (MRT) are the quintessential example of an epigenetic cancer. Mutation of a single gene, SMARCB1 or more rarely SMARCA4, is capable of causing one of the most aggressive and lethal cancers of early childhood and infancy. SMARCB1 encodes a core subunit of the SWI/SNF complex and its mutation evokes genome-wide downstream effects which may be counteracted therapeutically. Here we review and discuss the use of translational genomics in the study of MRT biology and the ways in which this has impacted clinical practice or may do so in the future. First, the diagnosis and definition of MRT and the transition from a histopathological to a molecular definition. Second, epigenetic and transcriptomic subgroups within MRT, their defining features and potential prognostic or therapeutic significance. Third, functional genomic studies of MRT by mouse modelling and forced re-expression of SMARCB1 in MRT cells. Fourth, studies of underlying epigenetic mechanisms (e.g. EZH2, HDACs) or deregulated kinases (e.g. PDGFR, FGFR1) and the potential therapeutic opportunities these provide. Finally, we discuss likely future directions and proffer opinion on how future translational genomics should be integrated into future biological/clinical studies to select and evaluate the best anti-MRT therapeutic agents.

EORTC SPECTA-AYA: A unique molecular profiling platform for adolescents and young adults with cancer in Europe

For most adolescent and young adult (AYA) cancers, age‐specific molecular features are poorly understood. EORTC‐SPECTA, an academic translational research infrastructure for biomaterial collection, will explicitly recruit AYA patients and will therefore collect empirical data to bridge the molecular gap between pediatric and adult oncology. The initial pilot study, activated in February 2019 across Europe, will recruit 100 AYA patients (aged 12–29 years) with newly diagnosed or relapsed high‐grade gliomas and high‐grade bone and soft tissue sarcomas. The primary objective of the pilot is to determine feasibility and recruitment rates. Formalin‐fixed tumor tissue and whole blood from study participants will be prospectively collected with clinical data and stored centrally at the Integrated BioBank of Luxembourg. Whole exome sequencing of matched tumor and blood, and tumor RNA sequencing and DNA methylation profiling will be performed at the German Cancer Research Center, Heidelberg, Germany. Virtual central pathology review of scanned diagnostic slides will be undertaken by an international expert panel, and diagnostic material returned to the participating centers. A multidisciplinary molecular tumor board will release a clinically validated report to referring clinicians within 4–6 weeks after biopsy. SPECTA‐AYA constitutes a major opportunity to gain knowledge about the tumor biology of this unique age group. It incorporates notable innovative aspects: AYA specificity, pan‐European academic collaboration, centralized biobanking, comprehensive molecular profiling and virtual central pathology review, among others. SPECTA‐AYA will help untangle the tumor particularities of AYAs with cancer and aims to improve their access to novel drugs and personalized medicine.

What's new?

To date, age‐specific molecular features remain poorly understood for most adolescent and young adult (AYA) cancers. This paper presents how SPECTA, a pan‐European academic translational research infrastructure for biomaterial collection, will specifically recruit AYA patients to bridge the molecular gap between pediatric and adult oncology. Further notable innovative aspects include centralized biobanking, comprehensive molecular profiling, and virtual central pathology review. SPECTA‐AYA, whose initial pilot study was launched in February 2019, constitutes a major opportunity to gain knowledge about the tumor biology of this unique age group and aims to improve the access of AYAs to novel drugs and personalized medicine.

Medulloblastoma

Medulloblastoma (MB) comprises a biologically heterogeneous group of embryonal tumours of the cerebellum. Four subgroups of MB have been described (WNT, sonic hedgehog (SHH), Group 3 and Group 4), each of which is associated with different genetic alterations, age at onset and prognosis. These subgroups have broadly been incorporated into the WHO classification of central nervous system tumours but still need to be accounted for to appropriately tailor disease risk to therapy intensity and to target therapy to disease biology. In this Primer, the epidemiology (including MB predisposition), molecular pathogenesis and integrative diagnosis taking histomorphology, molecular genetics and imaging into account are reviewed. In addition, management strategies, which encompass surgical resection of the tumour, cranio-spinal irradiation and chemotherapy, are discussed, together with the possibility of focusing more on disease biology and robust molecularly driven patient stratification in future clinical trials.