Preclinical drug screen reveals topotecan, actinomycin D, and volasertib as potential new therapeutic candidates for ETMR brain tumor patients

Targeting DNA Methylation Machinery in Pediatric Solid Tumors

DNA methylation is a key epigenetic regulatory mechanism that plays a critical role in a variety of cellular processes, including the regulation of cell fate during development, maintenance of cell identity, and genome stability. DNA methylation is tightly regulated by enzymatic reactions and its deregulation plays an important role in the development of cancer. Specific DNA methylation alterations have been found in pediatric solid tumors, providing new insights into the development of these tumors. In addition, DNA methylation profiles have greatly contributed to tune the diagnosis of pediatric solid tumors and to define subgroups of patients with different risks of progression, leading to the reduction in unwanted toxicity and the improvement of treatment efficacy. This review highlights the dysregulated DNA methylome in pediatric solid tumors and how this information provides promising targets for epigenetic therapies, particularly inhibitors of DNMT enzymes (DNMTis). Opportunities and limitations are considered, including the ability of DNMTis to induce viral mimicry and immune signaling by tumors. Besides intrinsic action against cancer cells, DNMTis have the potential to sensitize immune-cold tumors to immunotherapies and may represent a remarkable option to improve the treatment of challenging pediatric solid tumors.

Integrated proteomics spotlight the proteasome as a therapeutic vulnerability in embryonal tumors with multilayered rosettes

BACKGROUND

Embryonal tumors with multilayered rosettes (ETMR) are rare malignant embryonal brain tumors. The prognosis of ETMR is poor and novel therapeutic approaches are desperately needed. Comprehension of ETMR tumor biology is currently based on only few previous molecular studies, which mainly focused on the analyses of nucleic acids. In this study, we explored integrated ETMR proteomics.

METHODS

Using mass spectrometry, proteome data were acquired from 16 ETMR and the ETMR cell line BT183. Proteome data were integrated with case-matched global DNA methylation data, publicly available transcriptome data, and proteome data of further embryonal and pediatric brain tumors.

RESULTS

Proteome-based cluster analyses grouped ETMR samples according to histomorphology, separating neuropil-rich tumors with neuronal signatures from primitive tumors with signatures relating to stemness and chromosome organization. Integrated proteomics showcased that ETMR and BT183 cells harbor proteasome regulatory proteins in abundance, implicating their strong dependency on the proteasome machinery to safeguard proteostasis. Indeed, in vitro assays using BT183 highlighted that ETMR tumor cells are highly vulnerable toward treatment with the CNS penetrant proteasome inhibitor Marizomib.

CONCLUSIONS

In summary, histomorphology stipulates the proteome signatures of ETMR, and proteasome regulatory proteins are pervasively abundant in these tumors. As validated in vitro, proteasome inhibition poses a promising therapeutic option in ETMR.

PANCDR: precise medicine prediction using an adversarial network for cancer drug response

Pharmacogenomics aims to provide personalized therapy to patients based on their genetic variability. However, accurate prediction of cancer drug response (CDR) is challenging due to genetic heterogeneity. Since clinical data are limited, most studies predicting drug response use preclinical data to train models. However, such models might not be generalizable to external clinical data due to differences between the preclinical and clinical datasets. In this study, a Precision Medicine Prediction using an Adversarial Network for Cancer Drug Response (PANCDR) model is proposed. PANCDR consists of two sub-models, an adversarial model and a CDR prediction model. The adversarial model reduces the gap between the preclinical and clinical datasets, while the CDR prediction model extracts features and predicts responses. PANCDR was trained using both preclinical data and unlabeled clinical data. Subsequently, it was tested on external clinical data, including The Cancer Genome Atlas and brain tumor patients. PANCDR outperformed other machine learning models in predicting external test data. Our results demonstrate the robustness of PANCDR and its potential in precision medicine by recommending patient-specific drug candidates. The PANCDR codes and data are available at https://github.com/DMCB-GIST/PANCDR.

2021 World Health Organization Classification of Brain Tumors

OBJECTIVE

The classification of brain tumors is a rapidly evolving field that requires extensive integration of molecular diagnostic findings from an expanding set of platforms and assays. This article summarizes the schema presented in the 5th edition of the World Health Organization (WHO) classification of central nervous system (CNS) tumors while highlighting diagnostic molecular findings and discussing the strengths and weaknesses of commonly available testing modalities.

LATEST DEVELOPMENTS

Several major changes in practice were introduced with the 5th edition of the CNS WHO classification, including molecular grading of adult diffuse gliomas, the introduction of many new entities within the spectrum of pediatric gliomas and glioneuronal tumors, and the widespread adoption of methylation classes as useful or even necessary diagnostic criteria. Additionally, several revisions to nomenclature (eg, IDH-mutant gliomas) were introduced for simplicity and to disambiguate from other tumor types.

ESSENTIAL POINTS

The classification of brain tumors continues to grow in complexity alongside our improved understanding of their nuanced molecular underpinnings.

Class I HDAC inhibitor entinostat synergizes with PLK1 inhibitors in MYC-amplified medulloblastoma cells

PURPOSE

We and others have demonstrated that MYC-amplified medulloblastoma (MB) cells are susceptible to class I histone deacetylase inhibitor (HDACi) treatment. However, single drug treatment with HDACi has shown limited clinical efficacy. We hypothesized that addition of a second compound acting synergistically with HDACi may enhance efficacy.

METHODS

We used a gene expression dataset to identify PLK1 as a second target in MB cells and validated the relevance of PLK1 in MB. We measured cell metabolic activity, viability, and cycle progression in MB cells after treatment with PLK1-specific inhibitors (PLK1i). Chou-Talalay synergy calculations were used to determine the nature of class I HDACi entinostat and PLK1i interaction which was validated. Finally, the clinical potential of the combination was assessed in the in vivo experiment.

RESULTS

MYC-amplified tumor cells are highly sensitive towards treatment with ATP-competitive PLK1i as a monotherapy. Entinostat and PLK1i in combination act synergistically in MYC-driven MB cells, exerting cytotoxic effects at clinically relevant concentrations. The downstream effect is exerted via MYC-related pathways, pointing out the potential of MYC amplification as a clinically feasible predictive biomarker for patient selection. While entinostat significantly extended survival of mice implanted with orthotopic MYC-amplified MB PDX, there was no evidence of the improvement of survival when treating the animals with the combination.

CONCLUSION

The combination of entinostat and PLK1i showed synergistic interaction in vitro, but not in vivo. Therefore, further screening of blood-brain barrier penetrating PLK1i is warranted to determine the true potential of the combination as no on-target activity was observed after PLK1i volasertib treatment in vivo.

Childhood Brain Tumors: A Review of Strategies to Translate CNS Drug Delivery to Clinical Trials

Brain and spinal tumors affect 1 in 1000 people by 25 years of age, and have diverse histological, biological, anatomical and dissemination characteristics. A mortality of 30-40% means the majority are cured, although two-thirds have life-long disability, linked to accumulated brain injury that is acquired prior to diagnosis, and after surgery or chemo-radiotherapy. Only four drugs have been licensed globally for brain tumors in 40 years and only one for children. Most new cancer drugs in clinical trials do not cross the blood-brain barrier (BBB). Techniques to enhance brain tumor drug delivery are explored in this review, and cover those that augment penetration of the BBB, and those that bypass the BBB. Developing appropriate delivery techniques could improve patient outcomes by ensuring efficacious drug exposure to tumors (including those that are drug-resistant), reducing systemic toxicities and targeting leptomeningeal metastases. Together, this drug delivery strategy seeks to enhance the efficacy of new drugs and enable re-evaluation of existing drugs that might have previously failed because of inadequate delivery. A literature review of repurposed drugs is reported, and a range of preclinical brain tumor models available for translational development are explored.

Rare embryonal and sarcomatous central nervous system tumours: State-of-the art and future directions

The introduction of molecular methods into the diagnostics of central nervous system (CNS) tumours and the subsequent deciphering of their molecular heterogeneity has resulted in a significant impact on paediatric neurooncology. Particularly in the field of rare embryonal and sarcomatous CNS tumours, novel tumour types have been delineated and introduced in the recent 5th edition of the WHO classification of CNS tumours. The rarity and novelty of these tumour types result in diagnostic and therapeutic challenges. Apart from distinct histopathological and molecular features, these tumour types exhibit characteristic clinical properties and require different therapeutic approaches for optimal patient management. However, based on the limited availability of clinical data, current therapeutic recommendations have to be based on data from small, predominantly retrospective patient cohorts. Within this article, we provide guidance for diagnostic work-up and clinical management of rare CNS embryonal tumours ('embryonal tumour with multi-layered rosettes', ETMR; 'CNS neuroblastoma, FOXR2-activated', CNS NB-FOXR2; 'CNS tumour with BCOR-ITD, CNS BCOR-ITD) and rare CNS sarcomatous tumours ('primary intracranial sarcoma, DICER1-mutant', CNS DICER1; 'CIC-rearranged sarcoma', CNS CIC). By emphasizing the significant consequences on patient management in paediatric CNS tumours, we want to encourage wide implementation of comprehensive molecular diagnostics and stress the importance for joint international efforts to further collect and study these rare tumour types.

Clinical Management of Embryonal Tumor with Multilayered Rosettes: The CCMC Experience

OBJECTIVE

Embryonal tumors with multilayered rosettes (ETMRs) are highly aggressive pediatric brain tumors with poor prognosis. No standard treatment strategy for them exists because of their rarity. This study aimed to share experiences on the clinical diagnosis and treatment of ETMRs at China Children's Medical Center (CCMC).

METHODS

Patients who received a diagnosis of an ETMR between January 2017 and June 2020 were included. Clinical characteristics, such as age of onset, tumor size, stage, tumor site, treatment strategy, and clinical outcome, were retrospectively analyzed.

RESULTS

There were four boys and one girl within 4 years who received a diagnosis during this 4-year timeframe, and were thus included. The average age of morbidity was 29 months (range 16-66 months). The common clinical presentation was headaches and nausea caused by intracranial hypertension. All four patients were chromosome 19 microRNA cluster (C19MC) amplification positive. Two patients achieved complete remission, and one patient attained partial remission after multimodal treatment. Of the two deaths, one died from the rapid progression of the disease and another from tumor-related complications.

CONCLUSION

ETMRs are extremely rare brain tumors with a high, early mortality in children. Surgery is the mainstream treatment for ETMRs. Some patients may also benefit from postoperative adjuvant chemotherapy and radiotherapy.

Prognostic impact of the multimodal treatment approach in patients with C19MC-altered embryonal tumor with multilayered rosettes

OBJECTIVE

Embryonal tumor with multilayered rosettes (ETMR) is one of the childhood central nervous system tumors with the poorest prognosis; thus, establishing an optimal treatment strategy is essential, However, because of the low incidence and molecular heterogeneity of the tumor, the optimal treatment has not yet been determined. In this study the authors evaluated the prognostic impact of a multimodal treatment approach in patients with ETMR.

METHODS

The authors evaluated 4 patients with ETMR at their institution who showed varied clinical features and also conducted clinical characterization and prognostic analysis of previously reported cases of the ETMR-presenting locus 19q13.42 with a chromosome 19 microRNA cluster (C19MC) amplification, which is known to be a diagnostic hallmark of the tumor.

RESULTS

Of the 4 patients with ETMR in the authors' institution, in 1 case the patient's tumor showed a neuroblastoma-like appearance without multilayered rosettes; however, the diagnosis was confirmed by the presence of amplified C19MC. From a clinical standpoint, 2 patients who underwent gross-total resection (GTR) of the tumor and chemotherapy followed by high-dose chemotherapy (HDC) had long-term complete remission with or without local irradiation. In the multivariate analysis of 43 cases with C19MC-altered ETMR reported in the literature, HDC and local irradiation were significantly correlated with better event-free survival (HR 0.17, p = 0.0087; HR 0.17, p = 0.010) and overall survival (OS) (HR 0.29, p = 0.023; HR 0.28, p = 0.019), respectively. GTR was also correlated with better OS (HR 0.40, p = 0.039).

CONCLUSIONS

This case series demonstrated pathological and clinical heterogeneity among ETMR cases and the diagnostic importance of the molecular genetic approach among embryonal tumors, particularly during infancy. Based on the results of the analysis of molecularly uniformed ETMR cases, multimodal treatment may play a significant role in the prognosis of these tumors.

Promising Chemotherapy for Malignant Pediatric Brain Tumor in Recent Biological Insights

Brain tumors are the most widespread malignancies in children around the world. Chemotherapy plays a critical role in the treatment of these tumors. Although the current chemotherapy process has a remarkable outcome for a certain subtype of brain tumor, improving patient survival is still a major challenge. Further intensive treatment with conventional non-specific chemotherapy could cause additional adverse reactions without significant advancement in survival. Recently, patient derived brain tumor, xenograft, and whole genome analysis using deep sequencing technology has made a significant contribution to our understanding of cancer treatment. This realization has changed the focus to new agents, targeting the molecular pathways that are critical to tumor survival or proliferation. Thus, many novel drugs targeting epigenetic regulators or tyrosine kinase have been developed. These selective drugs may have less toxicity in normal cells and are expected to be more effective than non-specific chemotherapeutics. This review will summarize the latest novel targets and corresponding candidate drugs, which are promising chemotherapy for brain tumors according to the biological insights.

Embryonal and non-meningothelial mesenchymal tumors of the central nervous system - Advances in diagnosis and prognostication

The 5th edition of the WHO Classification of Tumours of the Central Nervous System introduces new entities, and provides updated guidance regarding the diagnostic criteria for tumors of the central nervous system (CNS). CNS embryonal tumors and CNS non‐meningothelial mesenchymal tumors can be challenging for practicing pathologists, as the histologic features are not always specific to a particular entity, and integration of microscopic and molecular findings is necessary. This review on CNS embryonal and non‐meningothelial mesenchymal tumors is meant to provide an update with a focus on WHO changes and additions and on recent discoveries with diagnostic, prognostic, and therapeutic implications.

Clinical phenotypes and prognostic features of embryonal tumours with multi-layered rosettes: a Rare Brain Tumor Registry study

BACKGROUND

Embryonal tumours with multi-layered rosettes (ETMRs) are a newly recognised, rare paediatric brain tumour with alterations of the C19MC microRNA locus. Due to varied diagnostic practices and scarce clinical data, disease features and determinants of outcomes for these tumours are poorly defined. We did an integrated clinicopathological and molecular analysis of primary ETMRs to define clinical phenotypes, and to identify prognostic factors of survival and key treatment modalities for this orphan disease.

METHODS

Paediatric patients with primary ETMRs and tissue available for analyses were identified from the Rare Brain Tumor Consortium global registry. The institutional histopathological diagnoses were centrally re-reviewed as per the current WHO CNS tumour guidelines, using histopathological and molecular assays. Only patients with complete clinical, treatment, and survival data on Nov 30, 2019, were included in clinicopathological analyses. Among patients who received primary multi-modal curative regimens, event-free survival and overall survival were determined using Cox proportional hazard and log-rank analyses. Univariate and multivariable Cox proportional hazard regression was used to estimate hazard ratios (HRs) with 95% CIs for clinical, molecular, or treatment-related prognostic factors.

FINDINGS

159 patients had a confirmed molecular diagnosis of primary ETMRs (median age at diagnosis 26 months, IQR 18-36) and were included in our clinicopathological analysis. ETMRs were predominantly non-metastatic (94 [73%] of 128 patients), arising from multiple sites; 84 (55%) of 154 were cerebral tumours and 70 (45%) of 154 arose at sites characteristic of other brain tumours. Hallmark C19MC alterations were seen in 144 (91%) of 159 patients; 15 (9%) were ETMR not otherwise specified. In patients treated with curative intent, event-free survival was 57% (95% CI 47-68) at 6 months and 31% (21-42) at 2 years; overall survival was 29% (20-38) at 2 years and 27% (18-37) at 4 years. Overall survival was associated with non-metastatic disease (HR 0·48, 95% CI 0·28-0·80; p=0·0057) and non-brainstem location (0·42 [0·22-0·81]; p=0·013) on univariate analysis, as well as with gross total resection (0·30, 0·16-0·58; p=0·0014), high-dose chemotherapy (0·35, 0·19-0·67; p=0·0020), and radiotherapy (0·21, 0·10-0·41; p<0·0001) on multivariable analysis. 2-year event-free and overall survival was 0% at 2 years in patients treated with conventional chemotherapy without radiotherapy (regardless of surgery extent), and 21% (95% CI 1-41) and 30% (6-54), respectively, in patients treated with high-dose chemotherapy, and gross total resection without radiotherapy. 2-year event-free survival in patients treated with high-dose chemotherapy and radiotherapy was 66% (95% CI 39-93) for patients with gross total resection and 44% (7-81) for patients with sub-total resection. 2-5-year overall survival was 66% (95% CI 33-99, p=0·038) for patients with gross total resection and 67% (36-98, p=0·0020) for patients with sub-total resection.

INTERPRETATION

Prompt molecular diagnosis and post-surgical treatment with intensive multi-modal therapy tailored to patient-specific risk features could improve ETMR survival.

FUNDING

Canadian Institute of Health Research, Canada Research Chair Awards, Australian Lions Childhood Cancer Research Foundation, Spanish Society of Pediatrics, Consejería de Salud y Familias de la Junta de Andalucía, Miracle Marnie, Phoebe Rose Rocks, Tali's Funds, Garron Cancer Centre, Grace's Walk, Meagan's Hug, Brainchild, Nelina's Hope, and Jean Martel Foundation.

Investigating the Central Nervous System Disposition of Actinomycin D: Implementation and Evaluation of Cerebral Microdialysis and Brain Tissue Measurements Supported by UPLC-MS/MS Quantification

Actinomycin D is a potent cytotoxic drug against pediatric (and other) tumors that is thought to barely cross the blood-brain barrier. To evaluate its potential applicability for the treatment of patients with central nervous system (CNS) tumors, we established a cerebral microdialysis model in freely moving mice and investigated its CNS disposition by quantifying actinomycin D in cerebral microdialysate, brain tissue homogenate, and plasma. For this purpose, we developed and validated an ultraperformance liquid chromatography-tandem mass spectrometry assay suitable for ultra-sensitive quantification of actinomycin D in the pertinent biological matrices in micro-samples of only 20 µL, with a lower limit of quantification of 0.05 ng/mL. In parallel, we confirmed actinomycin D as a substrate of P-glycoprotein (P-gp) in in vitro experiments. Two hours after intravenous administration of 0.5 mg/kg, actinomycin D reached total brain tissue concentrations of 4.1 ± 0.7 ng/g corresponding to a brain-to-plasma ratio of 0.18 ± 0.03, while it was not detectable in intracerebral microdialysate. This tissue concentration exceeds the concentrations of actinomycin D that have been shown to be effective in in vitro experiments. Elimination of the drug from brain tissue was substantially slower than from plasma, as shown in a brain-to-plasma ratio of approximately 0.53 after 22 h. Because actinomycin D reached potentially effective concentrations in brain tissue in our experiments, the drug should be further investigated as a therapeutic agent in potentially susceptible CNS malignancies, such as ependymoma.

Therapeutic implications of improved molecular diagnostics for rare CNS-embryonal tumor entities: results of an international, retrospective study

BACKGROUND

Only few data are available on treatment-associated behavior of distinct rare CNS-embryonal tumor entities previously treated as "CNS-primitive neuroectodermal tumors" (CNS-PNET). Respective data on specific entities, including CNS neuroblastoma, FOXR2 activated (CNS NB-FOXR2), and embryonal tumor with multi-layered rosettes (ETMR) are needed for development of differentiated treatment strategies.

METHODS

Within this retrospective, international study, tumor samples of clinically well-annotated patients with the original diagnosis of CNS-PNET were analyzed using DNA methylation arrays (n=307). Additional cases (n=66) with DNA methylation pattern of CNS NB-FOXR2 were included irrespective of initial histological diagnosis. Pooled clinical data (n=292) were descriptively analyzed.

RESULTS

DNA methylation profiling of "CNS-PNET" classified 58(19%) cases as ETMR, 57(19%) as HGG, 36(12%) as CNS NB-FOXR2, and 89(29%) cases were classified into 18 other entities. Sixty-seven (22%) cases did not show DNA methylation patterns similar to established CNS tumor reference classes. Best treatment results were achieved for CNS NB-FOXR2 patients (5-year PFS: 63%±7%, OS: 85%±5%, n=63), with 35/42 progression-free survivors after upfront craniospinal irradiation (CSI) and chemotherapy. The worst outcome was seen for ETMR and HGG patients with 5-year PFS of 18%±6% and 22%±7%, and 5-year OS of 24%±6% and 25%±7%, respectively.

CONCLUSION

The historically reported poor outcome of CNS-PNET patients becomes highly variable when tumors are molecularly classified based on DNA methylation profiling. Patients with CNS NB-FOXR2 responded well to current treatments and a standard-risk-CSI based regimen may be prospectively evaluated. The poor outcome of ETMR across applied treatment strategies substantiates the necessity for evaluation of novel treatments.

Treatment of Embryonal Tumours with Multilayered Rosettes with Carboplatin/Etoposide Induction and High-dose Chemotherapy within the Prospective P-HIT Trial

BACKGROUND

Embryonal tumours with multilayered rosettes (ETMR) are highly aggressive tumours occurring in early childhood. Published clinical data refer to retrospective, heterogeneously treated cohorts. Here, we describe the outcome of patients treated according to the prospective P-HIT trial and subsequent HIT2000-interim-registry.

PATIENTS AND METHODS

Age-stratified treatment included carboplatin/etoposide-induction, tandem-high-dose chemotherapy ("CARBO/ETO+HDCT") and response-stratified radiotherapy. Patients with centrally reviewed neuropathological and molecularly confirmed diagnosis of ETMR recruited within the P-HIT trial (2001-2011; n=19), the HIT2000-interim-registry (2012-2014; n=12) and earlier HIT-trials (n=4) were selected for analysis.

RESULTS

Age-adjusted incidence rate was 1.35 per 1 million children (aged 1-4 years) in the years 2012-2014. Median age at diagnosis for 35 patients was 2.9 years. Metastases at diagnosis were detected in 9 patients. One patient died due to postoperative complications. For 30 patients with non-brainstem tumour location, 5-year progression-free (PFS) and overall survival (OS) were 35% and 47% after treatment with CARBO/ETO+HDCT (n=17), compared to 0% and 8% with other treatments (n=13, p[OS]=0.011). All 4 patients with brainstem tumour died within 10 months after diagnosis. By multivariable analysis, supratentorial location: (HR[PFS]:0.07 [95%CI:0.01-0.38], p=0.003), localised disease (M0): (HR[OS] M0, no residual tumor:0.30 [95%CI:0.009-1.09], p=0.068; M0, residual tumor:0.18 [95%CI: 0.04-0.76], p=0.020) and CARBO/ETO+HDCT treatment (HR[OS]:0.16 [95%CI:0.05-054], p=0.003) were identified as independent prognostic factors. Of 9 survivors, 6 were treated with radiotherapy (craniospinal 4; local 2).

CONCLUSIONS

Our data indicate improved survival with intensified chemotherapy (CARBO/ETO+HDCT). However, despite intensive treatment, the outcome was poor. Thus, innovative therapies need to be evaluated urgently in an upfront setting.

Embryonal tumors of the central nervous system

PURPOSE OF REVIEW

This review aims to give an update on histopathological, molecular and clinical features of central nervous system (CNS) 'embryonal' tumors.

RECENT FINDINGS

The taxonomy of previously called 'CNS primitive neuroectodermal tumor' (CNS PNET) has been deeply modified since the discovery of specific molecular profiles for each various sub-entity of these rare, mainly pediatric, tumors. The term 'embryonal tumors' now refers to medulloblastomas, atypical teratoid rhabdoid tumors (AT/RT) and other rare entities, defined by their specific histopathological features together with expression-based or methylation-based profiling; specific gene mutations or fusions characterize some tumor types. In addition, the compilation of large series of molecular data has allowed to dissecting several of these tumor types in molecular subgroups, increasing the number of tumor entities, and leading to an amazingly complex nosology of rare-to-extremely rare malignancies. This rarity precludes from having strong evidence-based therapeutic recommendations, although international efforts are conducted to define the best treatment strategies.

SUMMARY

Embryonal tumors now correspond to molecularly well defined entities, which deserve further international collaborations to specify their biology and the appropriate burden of treatment, in order to minimize the long-term side-effects of treatment of these overall rare and severe diseases of childhood.

Embryonal tumors with multilayered rosettes: A tertiary care centre experience

BACKGROUND

Embryonal tumors with multilayered rosettes (ETMR) is an extremely rare and highly aggressive tumor. It includes three distinct entities i.e, embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma (EBL) and medulloepithelioma (MEPL). Here, we present our institutional experience of seven ETMR cases treated over a period of five years.

MATERIALS AND METHODS

Patients' records from 2015 to 2019 were reviewed manually and electronically to retrieve the data. Clinicopathological and outcome details of ETMR cases were entered in a predesigned proforma.

RESULTS

A total of seven cases of ETMR were registered from 2015 to 2019 with a median age at presentation of four years (range 3-7 years). All patients underwent surgery. However, only three patients completed the planned adjuvant treatment, comprising of focal radiotherapy (RT) alone, craniospinal irradiation (CSI) alone and CSI followed by six cycles of chemotherapy in one patient each respectively. Two patients commenced CSI but deteriorated during RT and thereafter needed best supportive care. Two patients could not be started on any adjuvant treatment. Unfortunately, six patients succumbed to their disease within one year of their diagnosis. Only one patient who received both CSI and adjuvant chemotherapy is alive at 15 months of diagnosis.

CONCLUSION

ETMR is a rare and aggressive entity. Majority of the patients die within one year of the diagnosis despite multimodality treatment.

Potential Importance of Early Focal Radiotherapy Following Gross Total Resection for Long-Term Survival in Children With Embryonal Tumors With Multilayered Rosettes

Embryonal tumor with multilayered rosettes (ETMR) is a rare, aggressive embryonal central nervous system tumor characterized by LIN28A expression and alterations in the C19MC locus. ETMRs predominantly occur in young children, have a dismal prognosis, and no definitive treatment guidelines have been established. We report on nine consecutive patients and review the role of initiation/timing of radiotherapy on survival. Between 2006 and 2018, nine patients were diagnosed with ETMR. Diagnosis was confirmed histopathologically, immunohistochemically and molecularly. Median age was 25 months (5–38). Location was supratentorial in five, pineal in three, and brainstem in one. Seven patients had a gross total resection, one a partial resection and one a biopsy at initial diagnosis. Chemotherapy augmented with intrathecal therapy started a median of 10 days (7–20) after surgery. Only two patients who after gross total resection received radiotherapy very early on (six weeks after diagnosis) are alive and in complete remission 56 and 50 months after diagnosis. All remaining patients for whom radiotherapy was deferred until the end of chemotherapy recurred, albeit none with leptomeningeal disease. A literature research identified 228 patients with ETMR. Including our patients only 26 (11%) of 237 patients survived >36 months with no evidence of disease at last follow-up. All but two long-term (>36 months) survivors received radiotherapy, ten of whom early on following gross total resection (GTR). GTR followed by early focal radiotherapy and intrathecal therapy to prevent leptomeningeal disease are potentially important to improve survival of ETMR in the absence of effective targeted therapies.

Embryonal tumors with multi-layered rosettes: a disease of dysregulated miRNAs

INTRODUCTION

ETMRs are highly lethal, pediatric embryonal brain tumors, previously classified as various histologic diagnoses including supratentorial primitive neuroectodermal tumors (sPNET) and CNS PNET. With recognition that these tumors harbor recurrent amplification of a novel oncogenic miRNA cluster on chr19, C19MC, ETMRs were designated as a distinct biological and molecular entity with a spectrum of histologic and clinical manifestations.

METHODS

We reviewed published literature describing clinical presentation, the genetic and epigenetic drivers of oncogenesis, and recent therapeutic strategies adopted to combat these aggressive tumors.

RESULTS

As a consequence of C19MC amplification, ETMRs upregulate several oncogenic and pluripotency proteins, including LIN28A, DNMT3B and MYCN, that confer a unique epigenetic signature reminiscent of nascent embryonic stem cells. In this review, we focus on the dysregulation of miRNAs in ETMR, the major pathogenic mechanism identified in this disease.

CONCLUSION

Despite the use of multi-modal therapeutic regimens, ETMR patients have dismal survival. Understanding the unique biology of these tumors has provided new insights towards novel therapeutic targets.

Functional Precision Medicine Identifies New Therapeutic Candidates for Medulloblastoma

Medulloblastoma is among the most common malignant brain tumors in children. Recent studies have identified at least four subgroups of the disease that differ in terms of molecular characteristics and patient outcomes. Despite this heterogeneity, most patients with medulloblastoma receive similar therapies, including surgery, radiation, and intensive chemotherapy. Although these treatments prolong survival, many patients still die from the disease and survivors suffer severe long-term side effects from therapy. We hypothesize that each patient with medulloblastoma is sensitive to different therapies and that tailoring therapy based on the molecular and cellular characteristics of patients' tumors will improve outcomes. To test this, we assembled a panel of orthotopic patient-derived xenografts (PDX) and subjected them to DNA sequencing, gene expression profiling, and high-throughput drug screening. Analysis of DNA sequencing revealed that most medulloblastomas do not have actionable mutations that point to effective therapies. In contrast, gene expression and drug response data provided valuable information about potential therapies for every tumor. For example, drug screening demonstrated that actinomycin D, which is used for treatment of sarcoma but rarely for medulloblastoma, was active against PDXs representing Group 3 medulloblastoma, the most aggressive form of the disease. Functional analysis of tumor cells was successfully used in a clinical setting to identify more treatment options than sequencing alone. These studies suggest that it should be possible to move away from a one-size-fits-all approach and begin to treat each patient with therapies that are effective against their specific tumor. SIGNIFICANCE: These findings show that high-throughput drug screening identifies therapies for medulloblastoma that cannot be predicted by genomic or transcriptomic analysis.

A modified IRS-III chemotherapy regimen leads to prolonged survival in children with embryonal tumor with multilayer rosettes

Background

Embryonal tumor with multilayer rosettes (ETMR) is a rare CNS malignancy affecting young children that carries a very poor prognosis. Treatment with intensive surgical resection, radiotherapy, and high-dose chemotherapy is insufficient treatment in the vast majority of cases. Effective, biologically based therapies for this tumor are therefore desperately needed. The Dana-Farber Cancer Institute–modified IRS-III protocol incorporates preclinically active agents, such as doxorubicin and actinomycin D, into the treatment regimen for ETMR and may improve patient outcomes.

Methods

The authors present a case series of 5 children with ETMR treated with an IRS-III-based chemotherapy backbone.

Results

All 5 patients received a gross-total tumor resection. Patients received between 12 and 51 weeks of IRS-III therapy at the discretion of their treating physician. Four patients received focal radiation therapy, with the fifth patient instead receiving a cycle of high-dose chemotherapy with autologous stem cell rescue. Four patients have progression-free survival of more than 18 months. Chemotherapy treatment was reasonably tolerated by all 5 patients with one case of mild sinusoidal obstructive syndrome and one case of Grade 3 peripheral neuropathy.

Conclusions

The patient outcomes in this small cohort are far better than would be expected based on the historical survival for this tumor. Given the tremendous need for effective therapy for ETMR, further investigation of this approach is warranted. An international consensus protocol based on the IRS-III regimen has been developed and will be available through a multicenter clinical trial and a global treatment registry.

ETMR: a tumor entity in its infancy

Embryonal tumor with Multilayered Rosettes (ETMR) is a relatively rare but typically deadly type of brain tumor that occurs mostly in infants. Since the discovery of the characteristic chromosome 19 miRNA cluster (C19MC) amplification a decade ago, the methods for diagnosing this entity have improved and many new insights in the molecular landscape of ETMRs have been acquired. All ETMRs, despite their highly heterogeneous histology, are characterized by specific high expression of the RNA-binding protein LIN28A, which is, therefore, often used as a diagnostic marker for these tumors. ETMRs have few recurrent genetic aberrations, mainly affecting the miRNA pathway and including amplification of C19MC (embryonal tumor with multilayered rosettes, C19MC-altered) and mutually exclusive biallelic DICER1 mutations of which the first hit is typically inherited through the germline (embryonal tumor with multilayered rosettes, DICER1-altered). Identification of downstream pathways affected by the deregulated miRNA machinery has led to several proposed potential therapeutical vulnerabilities including targeting the WNT, SHH, or mTOR pathways, MYCN or chromosomal instability. However, despite those findings, treatment outcomes have only marginally improved, since the initial description of this tumor entity. Many patients do not survive longer than a year after diagnosis and the 5-year overall survival rate is still lower than 30%. Thus, there is an urgent need to translate the new insights in ETMR biology into more effective treatments. Here, we present an overview of clinical and molecular characteristics of ETMRs and the current progress on potential targeted therapies.

Embryonal Tumors of the Central Nervous System: An Update

Embryonal tumors of the central nervous system (CNS) are rare, high-grade neoplasms predominantly affecting the pediatric population. Well-defined embryonal tumors include medulloblastoma, atypical teratoid/rhabdoid tumor, embryonal tumor with multilayered rosettes, C19MC-altered and embryonal tumor with multilayered rosettes, not otherwise specified, pineoblastoma, pituitary blastoma, CNS neuroblastoma, and ganglioneuroblastoma. Although their prognosis is nearly uniformly poor, the rapidly evolving understanding of their molecular biology contributes to diagnosis, prognosis, treatment, and clinical trial participation. Knowledge of current tumor stratification and diagnostic techniques will help pathologists guide care and preserve tissue for necessary or desired additional testing.

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.

The molecular landscape of ETMR at diagnosis and relapse

Embryonal tumours with multilayered rosettes (ETMRs) are aggressive paediatric embryonal brain tumours with a universally poor prognosis1. Here we collected 193 primary ETMRs and 23 matched relapse samples to investigate the genomic landscape of this distinct tumour type. We found that patients with tumours in which the proposed driver C19MC2-4 was not amplified frequently had germline mutations in DICER1 or other microRNA-related aberrations such as somatic amplification of miR-17-92 (also known as MIR17HG). Whole-genome sequencing revealed that tumours had an overall low recurrence of single-nucleotide variants (SNVs), but showed prevalent genomic instability caused by widespread occurrence of R-loop structures. We show that R-loop-associated chromosomal instability can be induced by the loss of DICER1 function. Comparison of primary tumours and matched relapse samples showed a strong conservation of structural variants, but low conservation of SNVs. Moreover, many newly acquired SNVs are associated with a mutational signature related to cisplatin treatment. Finally, we show that targeting R-loops with topoisomerase and PARP inhibitors might be an effective treatment strategy for this deadly disease.

Profile of the Intervention Potential of the Phylum Actinobacteria Toward Quorum Sensing and Other Microbial Virulence Strategies

The rapid dissemination of antimicrobial resistance amongst microorganisms and their deleterious effect on public health has propelled the exploration of alternative interventions that target microbial virulence rather than viability. In several microorganisms, the expression of virulence factors is controlled by quorum sensing systems. A comprehensive understanding into microbial quorum sensing systems, virulence strategies and pathogenesis has exposed potential targets whose attenuation may alleviate infectious diseases. Such virulence attenuating natural products sourced from the different phyla of bacteria from diverse ecosystems have been identified. In this review, we discuss chemical entities derived from the phylum Actinobacteria that have demonstrated the potential to inhibit microbial biofilms, enzymes, and other virulence factors both in vivo and in vitro. We also review Actinobacteria-derived compounds that can degrade quorum sensing signal molecules, and the genes encoding such molecules. As many Actinobacteria-derived compounds have been translated into pharmaceutically important agents including antibiotics, the identification of virulence attenuating compounds from this phylum exemplifies their significance as a prospective source for anti-virulent drugs.

Actinobacteria Derived from Algerian Ecosystems as a Prominent Source of Antimicrobial Molecules

Actinobacteria, in particular "rare actinobacteria" isolated from extreme ecosystems, remain the most inexhaustible source of novel antimicrobials, offering a chance to discover new bioactive metabolites. This is the first overview on actinobacteria isolated in Algeria since 2002 to date with the aim to present their potential in producing bioactive secondary metabolites. Twenty-nine new species and one novel genus have been isolated, mainly from the Saharan soil and palm groves, where 37.93% of the most abundant genera belong to Saccharothrix and Actinopolyspora. Several of these strains were found to produce antibiotics and antifungal metabolites, including 17 new molecules among the 50 structures reported, and some of these antibacterial metabolites have shown interesting antitumor activities. A series of approaches used to enhance the production of bioactive compounds is also presented as the manipulation of culture media by both classical methods and modeling designs through statistical strategies and the associations with diverse organisms and strains. Focusing on the Algerian natural sources of antimicrobial metabolites, this work is a representative example of the potential of a closely combined study on biology and chemistry of natural products.

Modeling improved production of the chemotherapeutic polypeptide actinomycin D by a novel Streptomyces sp. strain from a Saharan soil

The novel bioactive actinobacterial strain GSBNT10 obtained from a Saharan soil, was taxonomically characterized using a polyphasic approach. 16S rRNA gene sequence analysis supported the classification of the isolate within the genus Streptomyces indicating it as a novel species. The major metabolite responsible of the bioactivity was purified and structurally characterized as actinomycin D (act-D) by mass spectrometric and nuclear magnetic resonance analyses Plackett-Burman design (PBD) and response surface methodology (RSM) were applied in order to optimize the medium formulation for the production of this bioactive metabolite. By PBD experiments, NaNO₃, K₂HPO₄ and initial pH value were selected as significant variables affecting the metabolite production. Central Composite Design (CCD) showed that adjustment of the fermentative medium at pH 8.25, K₂HPO₄ at 0.2 gL^-1 and NaNO₃ at 3.76 gL^-1 were the values suiting the production of act-D. Moreover, the results obtained by the statistical approach were confirmed by act-D detection using the HPLC equipped with a diode array detector and coupled online with electrospray-mass spectrometry (ESIMS) technique. act-D production was highly stimulated, obtaining a good yield (656.46 mgL^-1) which corresponds to a 58.56% increase compared with the non-optimized conditions and data from LC-ESIMS technique efficiently confirmed the forecast from RSM.

Systematic Review of Patient-Derived Xenograft Models for Preclinical Studies of Anti-Cancer Drugs in Solid Tumors

Patient-derived xenograft (PDX) models are used as powerful tools for understanding cancer biology in PDX clinical trials and co-clinical trials. In this systematic review, we focus on PDX clinical trials or co-clinical trials for drug development in solid tumors and summarize the utility of PDX models in the development of anti-cancer drugs, as well as the challenges involved in this approach, following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Recently, the assessment of drug efficacy by PDX clinical and co-clinical trials has become an important method. PDX clinical trials can be used for the development of anti-cancer drugs before clinical trials, with their efficacy assessed by the modified response evaluation criteria in solid tumors (mRECIST). A few dozen cases of PDX models have completed enrollment, and the efficacy of the drugs is assessed by 1 × 1 × 1 or 3 × 1 × 1 approaches in the PDX clinical trials. Furthermore, co-clinical trials can be used for personalized care or precision medicine with the evaluation of a new drug or a novel combination. Several PDX models from patients in clinical trials have been used to assess the efficacy of individual drugs or drug combinations in co-clinical trials.

Embryonal Tumors of the Central Nervous System in Children: The Era of Targeted Therapeutics

Embryonal tumors (ET) of the central nervous system (CNS) in children encompass a wide clinical spectrum of aggressive malignancies. Until recently, the overlapping morphological features of these lesions posed a diagnostic challenge and undermined discovery of optimal treatment strategies. However, with the advances in genomic technology and the outpouring of biological data over the last decade, clear insights into the molecular heterogeneity of these tumors are now well delineated. The major subtypes of ETs of the CNS in children include medulloblastoma, atypical teratoid rhabdoid tumor (ATRT), and embryonal tumors with multilayered rosettes (ETMR), which are now biologically and clinically characterized as different entities. These important developments have paved the way for treatments guided by risk stratification as well as novel targeted therapies in efforts to improve survival and reduce treatment burden.

Extracranial extra-CNS spread of embryonal tumor with multilayered rosettes (ETMR): case series and systematic review

BACKGROUND

Embryonal tumors with multilayered rosettes (ETMR) is a rare variant of embryonal tumor of infancy with nearly 200 cases reported in the literature. Leptomeningeal spread of this tumor is well known; however, extracranial metastasis has been sparsely reported in the literature.

METHODS

Our study was divided into two sections: (1) We conducted a retrospective review of our patient series of ETMR and screened for patients with evidence of ETMR over the last 10 years 2007-2017 at a single tertiary referral pediatric hospital, and (2) we conducted a systematic review according to PRISMA guidelines of all reported cases of ETMR to determine the incidence of extracranial metastasis and treatment paradigms.

RESULTS

Here we report three cases of extracranial non-CNS spread of ETMR and conduct a systematic review of ETMR to improve our understanding of ETMR metastases and treatment paradigms. In our systematic review (n = 204), median overall survival was less than 1 year with 44.1% children surviving over 1 year. Previously, only five cases of extracranial metastasis of ETMR have been reported.

CONCLUSIONS

Our case series (n = 3) and review demonstrate that these tumors may behave like soft tissue sarcomas and may be susceptible to tumor seeding through surgical manipulation or by CSF (ventriculoperitoneal shunt). Surgery for tumor recurrence may offer an improved local disease control, but preventative measures such as meticulous surgical resection may be necessary to reduce intraoperative contamination.