Precision medicine in pediatric oncology

Molecular Alterations in Pediatric Solid Tumors

Pediatric tumors can be divided into hematologic malignancies, central nervous system tumors, and extracranial solid tumors of bone, soft tissue, or other organ systems. Molecular alterations that impact diagnosis, prognosis, treatment, and familial cancer risk have been described in many pediatric solid tumors. In addition to providing a concise summary of clinically relevant molecular alterations in extracranial pediatric solid tumors, this review discusses conventional and next-generation sequencing-based molecular techniques, relevant tumor predisposition syndromes, and the increasing integration of molecular data into the practice of diagnostic pathology for children with solid tumors.

Adjuvant Wilms' tumour 1-specific dendritic cell immunotherapy complementing conventional therapy for paediatric patients with high-grade glioma and diffuse intrinsic pontine glioma: protocol of a monocentric phase I/II clinical trial in Belgium

INTRODUCTION

Diffuse intrinsic pontine glioma (DIPG) and paediatric high-grade glioma (pHGG) are aggressive glial tumours, for which conventional treatment modalities fall short. Dendritic cell (DC)-based immunotherapy is being investigated as a promising and safe adjuvant therapy. The Wilms' tumour protein (WT1) is a potent target for this type of antigen-specific immunotherapy and is overexpressed in DIPG and pHGG. Based on this, we designed a non-randomised phase I/II trial, assessing the feasibility and safety of WT1 mRNA-loaded DC (WT1/DC) immunotherapy in combination with conventional treatment in pHGG and DIPG.

METHODS AND ANALYSIS

10 paediatric patients with newly diagnosed or pretreated HGG or DIPG were treated according to the trial protocol. The trial protocol consists of leukapheresis of mononuclear cells, the manufacturing of autologous WT1/DC vaccines and the combination of WT1/DC-vaccine immunotherapy with conventional antiglioma treatment. In newly diagnosed patients, this comprises chemoradiation (oral temozolomide 90 mg/m2 daily+radiotherapy 54 Gy in 1.8 Gy fractions) followed by three induction WT1/DC vaccines (8-10×106 cells/vaccine) given on a weekly basis and a chemoimmunotherapy booster phase consisting of six 28-day cycles of oral temozolomide (150-200 mg/m2 on days 1-5) and a WT1/DC vaccine on day 21. In pretreated patients, the induction and booster phase are combined with best possible antiglioma treatment at hand. Primary objectives are to assess the feasibility of the production of mRNA-electroporated WT1/DC vaccines in this patient population and to assess the safety and feasibility of combining conventional antiglioma treatment with the proposed immunotherapy. Secondary objectives are to investigate in vivo immunogenicity of WT1/DC vaccination and to assess disease-specific and general quality of life.

ETHICS AND DISSEMINATION

The ethics committee of the Antwerp University Hospital and the University of Antwerp granted ethics approval. Results of the clinical trial will be shared through publication in a peer-reviewed journal and presentations at conferences.

TRIAL REGISTRATION NUMBER

NCT04911621.

Family Recall of and Response to Germline Pathologic Variants Found on Paired Tumor-Germline Sequencing in Pediatric Oncology

PURPOSE

Paired tumor-germline sequencing can identify somatic variants for targeted therapy and germline pathogenic variants (GPVs) causative of hereditary cancer/tumor predisposition syndromes. It is unknown how patients/families in pediatric oncology use information about an identified GPV. We assessed recall of germline results and actions taken on the basis of findings.

METHODS

We completed phone surveys with patients (and/or their parent) with GPVs identified via a single academic medical center's paired tumor-germline sequencing study. Seven hundred forty pediatric (aged 0-25 years) oncology patients were enrolled in this sequencing study between May 2012 and August 2021. Ninety-six participants (13.0%) had at least one GPV identified and were therefore eligible for this survey. The parent/guardian (for patients younger than 18 years or deceased patients) or patients themselves (if 18 years or older) were contacted. Survey topics included germline result recall, experience with genetic counseling, changes to patient's cancer treatment/screening, sharing of results with family members, and lifestyle changes.

RESULTS

Fifty-three surveys (response rate, 55.2%) were completed between October 2021 and June 2022. Thirty-seven (69.8%) respondents correctly recalled the identified GPV. Discussing results with a genetic counselor (P = .0001), having a GPV related to the cancer/tumor diagnosis (P = .002), and non-Hispanic White race/ethnicity (P = .02) were associated with accurate recall. Twenty-five respondents (47.2%) reported a change in the child's cancer treatment and/or screening recommendations, 17 respondents (32.1%) made a lifestyle change on the basis of the results, and 44 respondents (83.0%) shared results with at least one family member.

CONCLUSION

While most respondents remembered that a GPV was identified in the patient, some did not recall having a GPV found, and others recalled germline findings incorrectly. Future work may determine patient/family preferences for timing/method of result return to optimize patient recall and use of germline results.

The Health Care Utilization and Medical Costs in Long-Term Follow-Up of Children Diagnosed With Leukemia, Solid Tumor, or Brain Tumor: Population-Based Study Using the National Health Insurance Claims Data

BACKGROUND

Childhood cancer survivors are at a high risk of medical consequences of their disease and treatment. There is growing information about the long-term health issues of childhood cancer survivors; however, there are very few studies describing the health care utilization and costs for this unique population. Understanding their utilization of health care services and costs will provide the basis for developing strategies to better serve these individuals and potentially reduce the cost.

OBJECTIVE

This study aims to determine the utilization of health services and costs for long-term survivors of childhood cancer in Taiwan.

METHODS

This is a nationwide, population-based, retrospective case-control study. We analyzed the claims data of the National Health Insurance that covers 99% of the Taiwanese population of 25.68 million. A total of 33,105 children had survived for at least 5 years after the first appearance of a diagnostic code of cancer or a benign brain tumor before the age of 18 years from 2000 to 2010 with follow-up to 2015. An age- and gender-matched control group of 64,754 individuals with no cancer was randomly selected for comparison. Utilization was compared between the cancer and no cancer groups by χ2 test. The annual medical expense was compared by the Mann-Whitney U test and Kruskal-Wallis rank-sum test.

RESULTS

At a median follow-up of 7 years, childhood cancer survivors utilized a significantly higher proportion of medical center, regional hospital, inpatient, and emergency services in contrast to no cancer individuals: 57.92% (19,174/33,105) versus 44.51% (28,825/64,754), 90.66% (30,014/33,105) versus 85.70% (55,493/64,754), 27.19% (9000/33,105) versus 20.31% (13,152/64,754), and 65.26% (21,604/33,105) versus 59.36% (38,441/64,754), respectively (all P<.001). The annual total expense (median, interquartile range) of childhood cancer survivors was significantly higher than that of the comparison group (US $285.56, US $161.78-US $535.80 per year vs US $203.90, US $118.98-US $347.55 per year; P<.001). Survivors with female gender, diagnosis before the age of 3 years, and diagnosis of brain cancer or a benign brain tumor had significantly higher annual outpatient expenses (all P<.001). Moreover, the analysis of outpatient medication costs showed that hormonal and neurological medications comprised the 2 largest costs in brain cancer and benign brain tumor survivors.

CONCLUSIONS

Survivors of childhood cancer and a benign brain tumor had higher utilization of advanced health resources and higher costs of care. The design of the initial treatment plan minimizing long-term consequences, early intervention strategies, and survivorship programs have the potential to mitigate costs of late effects due to childhood cancer and its treatment.

Correlation of Transcriptomics and FDG-PET SUVmax Indicates Reciprocal Expression of Stemness-Related Transcription Factor and Neuropeptide Signaling Pathways in Glucose Metabolism of Ewing Sarcoma

BACKGROUND

In Ewing sarcoma (EwS), long-term treatment effects and poor survival rates for relapsed or metastatic cases require individualization of therapy and the discovery of new treatment methods. Tumor glucose metabolic activity varies significantly between patients, and FDG-PET signals have been proposed as prognostic factors. However, the biological basis for the generally elevated but variable glucose metabolism in EwS is not well understood.

METHODS

We retrospectively included 19 EwS samples (17 patients). Affymetrix gene expression was correlated with maximal standardized uptake value (SUVmax) using machine learning, linear regression modelling, and gene set enrichment analyses for functional annotation.

RESULTS

Expression of five genes correlated (MYBL2, ELOVL2, NETO2) or anticorrelated (FAXDC2, PLSCR4) significantly with SUVmax (adjusted p-value ≤ 0.05). Additionally, we identified 23 genes with large SUVmax effect size, which were significantly enriched for "neuropeptide Y receptor activity (GO:0004983)" (adjusted p-value = 0.0007). The expression of the members of this signaling pathway (NPY, NPY1R, NPY5R) anticorrelated with SUVmax. In contrast, three transcription factors associated with maintaining stemness displayed enrichment of their target genes with higher SUVmax: RNF2, E2F family, and TCF3.

CONCLUSION

Our large-scale analysis examined comprehensively the correlations between transcriptomics and tumor glucose utilization. Based on our findings, we hypothesize that stemness may be associated with increased glucose uptake, whereas neuroectodermal differentiation may anticorrelate with glucose uptake.

Implementation of paediatric precision oncology into clinical practice: The Individualized Therapies for Children with cancer program ‘iTHER’

iTHER is a Dutch prospective national precision oncology program aiming to define tumour molecular profiles in children and adolescents with primary very high-risk, relapsed, or refractory paediatric tumours. Between April 2017 and April 2021, 302 samples from 253 patients were included. Comprehensive molecular profiling including low-coverage whole genome sequencing (lcWGS), whole exome sequencing (WES), RNA sequencing (RNA-seq), Affymetrix, and/or 850k methylation profiling was successfully performed for 226 samples with at least 20% tumour content. Germline pathogenic variants were identified in 16% of patients (35/219), of which 22 variants were judged causative for a cancer predisposition syndrome. At least one somatic alteration was detected in 204 (90.3%), and 185 (81.9%) were considered druggable, with clinical priority very high (6.1%), high (21.3%), moderate (26.0%), intermediate (36.1%), and borderline (10.5%) priority. iTHER led to revision or refinement of diagnosis in 8 patients (3.5%). Temporal heterogeneity was observed in paired samples of 15 patients, indicating the value of sequential analyses.

Of 137 patients with follow-up beyond twelve months, 21 molecularly matched treatments were applied in 19 patients (13.9%), with clinical benefit in few. Most relevant barriers to not applying targeted therapies included poor performance status, as well as limited access to drugs within clinical trial.

iTHER demonstrates the feasibility of comprehensive molecular profiling across all ages, tumour types and stages in paediatric cancers, informing of diagnostic, prognostic, and targetable alterations as well as reportable germline variants. Therefore, WES and RNA-seq is nowadays standard clinical care at the Princess Máxima Center for all children with cancer, including patients at primary diagnosis. Improved access to innovative treatments within biology-driven combination trials is required to ultimately improve survival.

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Implementing comprehensive molecular profiling into standard of care is feasible.

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Temporal heterogeneity is observed, indicating the value of sequential analyses.

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Molecularly matched treatments are applied in a minority of patients despite clinical benefit.

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Poor performance status & limited access to drugs within trial hamper targeted treatment.

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The multidisciplinary tumour board is crucial in translating findings into clinical decision making.

Precision Medicine Highlights Dysregulation of the CDK4/6 Cell Cycle Regulatory Pathway in Pediatric, Adolescents and Young Adult Sarcomas

Simple Summary

This review provides an overview of clinical features and current therapies in children, adolescents, and young adults (AYA) with sarcoma. It highlights the basic and clinical findings on the cyclin-dependent kinases 4 and 6 (CDK4/6) cell cycle regulatory pathway in the context of the precision medicine-based molecular profiles of the three most common types of pediatric and AYA sarcomas—osteosarcoma (OS), rhabdomyosarcoma (RMS), and Ewing sarcoma (EWS).

Abstract

Despite improved therapeutic and clinical outcomes for patients with localized diseases, outcomes for pediatric and AYA sarcoma patients with high-grade or aggressive disease are still relatively poor. With advancements in next generation sequencing (NGS), precision medicine now provides a strategy to improve outcomes in patients with aggressive disease by identifying biomarkers of therapeutic sensitivity or resistance. The integration of NGS into clinical decision making not only increases the accuracy of diagnosis and prognosis, but also has the potential to identify effective and less toxic therapies for pediatric and AYA sarcomas. Genome and transcriptome profiling have detected dysregulation of the CDK4/6 cell cycle regulatory pathway in subpopulations of pediatric and AYA OS, RMS, and EWS. In these patients, the inhibition of CDK4/6 represents a promising precision medicine-guided therapy. There is a critical need, however, to identify novel and promising combination therapies to fight the development of resistance to CDK4/6 inhibition. In this review, we offer rationale and perspective on the promise and challenges of this therapeutic approach.

Advocating for the surgical needs of children with cancer

Outcomes have improved significantly over the last 60 years for children with cancer. However, one consequence of improved survival is that many patients are now living with the long-term consequences of therapy. Pediatric surgeons can impact both the oncologic outcomes and morbidities of therapy. Therefore, it is incumbent upon us to be considerate, informed, and introspective about what we do as surgeons.

Metachronous, non-pineal, trilateral retinoblastoma in a patient with a seemingly reduced-expressivity RB1 germline deletion

The clinical course of trilateral retinoblastoma can be unpredictable, and expressivity of germline RB1 variants may vary during development. We describe an unexpected fatal case of trilateral retinoblastoma with an intracranial tumor in an unusual location and discuss genetic copy number analyses as a useful diagnostic tool with therapeutic potential.

The Current Landscape of Targeted Clinical Trials in Non-WNT/Non-SHH Medulloblastoma

Simple Summary

Medulloblastoma is a form of malignant brain tumor that arises predominantly in infants and young children and can be divided into different groups based on molecular markers. The group of non-WNT/non-SHH medulloblastoma includes a spectrum of heterogeneous subgroups that differ in their biological characteristics, genetic underpinnings, and clinical course of disease. Non-WNT/non-SHH medulloblastoma is currently treated with surgery, chemotherapy, and radiotherapy; however, new drugs are needed to treat patients who are not yet curable and to reduce treatment-related toxicity and side effects. We here review which new treatment options for non-WNT/non-SHH medulloblastoma are currently clinically tested. Furthermore, we illustrate the challenges that have to be overcome to reach a new therapeutic standard for non-WNT/non-SHH medulloblastoma, for instance the current lack of good preclinical models, and the necessity to conduct trials in a comparably small patient collective.

Abstract

Medulloblastoma is an embryonal pediatric brain tumor and can be divided into at least four molecularly defined groups. The category non-WNT/non-SHH medulloblastoma summarizes medulloblastoma groups 3 and 4 and is characterized by considerable genetic and clinical heterogeneity. New therapeutic strategies are needed to increase survival rates and to reduce treatment-related toxicity. We performed a noncomprehensive targeted review of the current clinical trial landscape and literature to summarize innovative treatment options for non-WNT/non-SHH medulloblastoma. A multitude of new drugs is currently evaluated in trials for which non-WNT/non-SHH patients are eligible, for instance immunotherapy, kinase inhibitors, and drugs targeting the epigenome. However, the majority of these trials is not restricted to medulloblastoma and lacks molecular classification. Whereas many new molecular targets have been identified in the last decade, which are currently tested in clinical trials, several challenges remain on the way to reach a new therapeutic strategy for non-WNT/non-SHH medulloblastoma. These include the severe lack of faithful preclinical models and predictive biomarkers, the question on how to stratify patients for clinical trials, and the relative lack of studies that recruit large, homogeneous patient collectives. Innovative trial designs and international collaboration will be a key to eventually overcome these obstacles.

Clinical Utility of Precision Medicine in Pediatric Oncology: A Systematic Review

PURPOSE

Precision medicine uses advanced molecular techniques to guide the use of targeted therapeutic drugs and is an emerging paradigm in pediatric oncology. Clinical evidence related to the efficacy of many novel targeted drugs, however, is currently very limited given the rarity of pediatric cancer and the lack of published evidence for the use of these drugs in children. This systematic review aimed to evaluate the existing evidence for the feasibility and clinical efficacy of precision medicine in pediatric oncology.

METHODS

A systematic review was conducted using the PubMed, Medline, and Embase databases. Clinical trials and observational studies, which used molecular assays such as whole-exome sequencing to identify molecular targets that guided the allocation of targeted cancer drugs and reported clinical outcomes, were included in this review.

RESULTS

Twenty-one clinical trials and observational studies were identified, collectively enrolling 1,408 pediatric patients across nine countries. Therapeutic targets were found in 647 patients (46.0%); however, only 175 of these patients (27.0%) received a targeted drug. Objective responses were recorded for 73 (41.7%) of these 175 patients, only 5.2% of the total sample. Inconsistent outcome reporting and limited comparison with conventional treatment hindered evaluation of the clinical utility of precision medicine.

CONCLUSION

Precision medicine can feasibly identify molecular targets in a clinical setting. However, the inaccessibility of targeted drugs is a significant barrier, restricting the exploration of its therapeutic potential in pediatric oncology. Future clinical trials should endeavor to link the molecular testing results with access to targeted drugs and standardize outcome reporting to advance understanding of the benefits of this novel paradigm in improving patient outcomes.

Cancer Stem Cells and their Management in Cancer Therapy

BACKGROUND

In the last decade, the proposed Cancer Stem Cell (CSC) hypothesis has steadily changed the way cancer treatment is approached. CSCs may be the source of the heterogeneous non-tumorigenic cell population included in a neoplasm. Intratumor and intertumoral heterogeneity is a well-known phenomenon that massively entangles the diagnosis and treatment of cancer. The literature seems to suggest that heterogeneity develops progressively within tumor-initiating stem cells. CSCs harbor genetic and/or epigenetic alterations that allow them to differentiate into multiple tumor cell types sequentially.

OBJECTIVE

The CSC hypothesis, cellular therapy, and the most recent patents on CSCs were reviewed.

METHODS

PubMed, Scopus, and Google Scholar were screened for this information. Also, an analysis of the most recent data targeting CSCs in pediatric cancer developed at two Canadian institutions is provided. The genes involved with the activation of CSCs and the drugs used to antagonize them are also highlighted.

RESULTS

It is underlined that (1) CSCs possess stem cell-like properties, including the ability for self-renewal; (2) CSCs can start carcinogenesis and are responsible for tumor recurrence after treatment; (3) Although some limitations have been raised, which may oppose the CSC hypothesis, cancer progression and metastasis have been recognized to be caused by CSCs.

CONCLUSION

The significant roles of cell therapy may include an auto-transplant with high-dose treatment, an improvement of the immune function, creation of chimeric antigen receptor T cells, and the recruitment of NK cell-based immunotherapy.

The Landscape of Pediatric Precision Oncology: Program Design, Actionable Alterations, and Clinical Trial Development

Over the last years, various precision medicine programs have been developed for pediatric patients with high-risk, relapsed, or refractory malignancies, selecting patients for targeted treatment through comprehensive molecular profiling. In this review, we describe characteristics of these initiatives, demonstrating the feasibility and potential of molecular-driven precision medicine. Actionable events are identified in a significant subset of patients, although comparing results is complicated due to the lack of a standardized definition of actionable alterations and the different molecular profiling strategies used. The first biomarker-driven trials for childhood cancer have been initiated, but until now the effect of precision medicine on clinical outcome has only been reported for a small number of patients, demonstrating clinical benefit in some. Future perspectives include the incorporation of novel approaches such as liquid biopsies and immune monitoring as well as innovative collaborative trial design including combination strategies, and the development of agents specifically targeting aberrations in childhood malignancies.

Molecular Alterations in Pediatric Solid Tumors

Pediatric tumors can be divided into hematologic malignancies, central nervous system tumors, and extracranial solid tumors of bone, soft tissue, or other organ systems. Molecular alterations that impact diagnosis, prognosis, treatment, and familial cancer risk have been described in many pediatric solid tumors. In addition to providing a concise summary of clinically relevant molecular alterations in extracranial pediatric solid tumors, this review discusses conventional and next-generation sequencing-based molecular techniques, relevant tumor predisposition syndromes, and the increasing integration of molecular data into the practice of diagnostic pathology for children with solid tumors.

Precision medicine in pediatric solid cancers

Despite huge advances in the diagnosis and treatment of pediatric cancers over the past several decades, it remains one of the leading causes of death during childhood in developed countries. The development of new targeted treatments for these diseases has been hampered by two major factors. First, the extremely heterogeneous nature of the types of tumors encountered in this age group, and their fundamental differences from common adult carcinomas, has made it hard to truly get a handle on the complexities of the underlying biology driving tumor growth. Second, a reluctance of the pharmaceutical industry to develop products or trials for this population due to the relatively small size of the 'market', and a too-easy mechanism of obtaining waivers for pediatric development of adult oncology drugs based on disease type rather than mechanism of action, led to significant difficulties in getting access to new drugs. Thankfully, the field has now started to change, both scientifically and from a regulatory perspective, in order to address some of these challenges. In this review, we will examine some of the recent insights into molecular features which make pediatric tumors so unique and how these might represent therapeutic targets; highlight ongoing international initiatives for providing comprehensive, personalized genomic profiling of childhood tumors in a clinically-relevant timeframe, and look briefly at where the field of pediatric precision oncology may be heading in future.

ACE2/Angiotensin-(1-7)/Mas Receptor Axis in Human Cancer: Potential Role for Pediatric Tumors

BACKGROUND

Pediatric tumors remain the highest cause of death in developed countries. Research on novel therapeutic strategies with lesser side effects is of utmost importance. In this scenario, the role of Renin-Angiotensin System (RAS) axes, the classical one formed by angiotensinconverting enzyme (ACE), Angiotensin II and AT1 receptor and the alternative axis composed by ACE2, Angiotensin-(1-7) and Mas receptor, have been investigated in cancer.

OBJECTIVE

This review aimed to summarize the pathophysiological role of RAS in cancer, evidence for anti-tumor effects of ACE2/Angiotensin-(1-7)/Mas receptor axis and future therapeutic perspectives for pediatric cancer.

METHODS

Pubmed, Scopus and Scielo were searched in regard to RAS molecules in human cancer and pediatric patients. The search terms were "RAS", "ACE", "Angiotensin-(1-7)", "ACE2", "Angiotensin II", "AT1 receptor", "Mas receptor", "Pediatric", "Cancer".

RESULTS

Experimental studies have shown that Angiotensin-(1-7) inhibits the growth of tumor cells and reduces local inflammation and angiogenesis in several types of cancer. Clinical trials with Angiotensin-( 1-7) or TXA127, a pharmaceutical grade formulation of the naturally occurring peptide, have reported promising findings, but not enough to recommend medical use in human cancer. In regard to pediatric cancer, only three articles that marginally investigated RAS components were found and none of them evaluated molecules of the alternative RAS axis.

CONCLUSION

Despite the potential applicability of Angiotensin-(1-7) in pediatric tumors, the role of this molecule was never tested. Further clinical trials are necessary, also including pediatric patients, to confirm safety and efficiency and to define therapeutic targets.

An institutional audit of the use of novel drugs in pediatric oncology

BACKGROUND

Significant challenges persist in treating children with rare, relapsed, or refractory malignancies. Novel molecularly targeted drugs promise improved outcomes for these children with reduced toxicity. However, there is often limited evidence to substantiate their clinical efficacy and guide their use. This raises issues for clinical decision-making, ethical concerns surrounding equity of access to these often-expensive agents, and the management of families' expectations for cure. This audit evaluated the off-label use of novel drugs and associated clinical outcomes in order to guide the development of future clinical and ethical guidelines.

AIM

To evaluate the patterns in the off-label use of novel drugs for treating childhood cancer and the associated clinical outcomes to guide prospective studies and inform ethical and clinical governance protocols for the use of these agents.

METHODS

A retrospective audit was performed for all patients who received novel drugs off-label as treatment for their malignancy at an Australian pediatric oncology center between 2010 and 2019.

RESULTS

One hundred patients with 32 unique diagnoses received 133 novel drugs across 124 regimens. Eighty-four patients received these drugs at the second line of treatment or greater. Novel drug median cost was $15 521 AUD (Range: $6.53 AUD to $258 339 AUD) and was primarily funded by the hospital (N = 60/133, 45.1%) or compassionate access from pharmaceutical companies (N = 52/133, 39.1%). Decision-making related to novel drugs was inconsistently documented. Ninety-one of 124 treatment regimens commenced between 2010 and 2019 resulted in objective responses (73.4%), but only 35 were still ongoing upon review in June 2020 (38.5%). Median response duration was 12.6 months (Range: 0-93.2 months).

CONCLUSIONS

While novel drugs were largely unable to definitively cure patients, most achieved objective responses. Prospective trials and more rigorous documentation are needed to fully inform the future use of these agents given the heterogeneity of their applications.

What Animal Cancers teach us about Human Biology

Cancers in animals present a large, underutilized reservoir of biomedical information with critical implication for human oncology and medicine in general. Discussing two distinct areas of tumour biology in non-human hosts, we highlight the importance of these findings for our current understanding of cancer, before proposing a coordinated strategy to harvest biomedical information from non-human resources and translate it into a clinical setting. First, infectious cancers that can be transmitted as allografts between individual hosts, have been identified in four distinct, unrelated groups, dogs, Tasmanian devils, Syrian hamsters and, surprisingly, marine bivalves. These malignancies might hold the key to improving our understanding of the interaction between tumour cell and immune system and, thus, allow us to devise novel treatment strategies that enhance anti-cancer immunosurveillance, as well as suggesting more effective organ and stem cell transplantation strategies. The existence of these malignancies also highlights the need for increased scrutiny when considering the existence of infectious cancers in humans. Second, it has long been understood that no linear relationship exists between the number of cells within an organism and the cancer incidence rate. To resolve what is known as Peto's Paradox, additional anticancer strategies within different species have to be postulated. These naturally occurring idiosyncrasies to avoid carcinogenesis represent novel potential therapeutic strategies.

Sarcoma treatment in the era of molecular medicine

Sarcomas are heterogeneous and clinically challenging soft tissue and bone cancers. Although constituting only 1% of all human malignancies, sarcomas represent the second most common type of solid tumors in children and adolescents and comprise an important group of secondary malignancies. More than 100 histological subtypes have been characterized to date, and many more are being discovered due to molecular profiling. Owing to their mostly aggressive biological behavior, relative rarity, and occurrence at virtually every anatomical site, many sarcoma subtypes are in particular difficult-to-treat categories. Current multimodal treatment concepts combine surgery, polychemotherapy (with/without local hyperthermia), irradiation, immunotherapy, and/or targeted therapeutics. Recent scientific advancements have enabled a more precise molecular characterization of sarcoma subtypes and revealed novel therapeutic targets and prognostic/predictive biomarkers. This review aims at providing a comprehensive overview of the latest advances in the molecular biology of sarcomas and their effects on clinical oncology; it is meant for a broad readership ranging from novices to experts in the field of sarcoma.

Compare and contrast: pediatric cancer versus adult malignancies

Cancer is a leading cause of death in both adults and children, but in terms of absolute numbers, pediatric cancer is a relatively rare disease. The rarity of pediatric cancer is consistent with our current understanding of how adult malignancies form, emphasizing the view of cancer as a genetic disease caused by the accumulation and selection of unrepaired mutations over time. However, considering those children who develop cancer merely as stochastically "unlucky" does not fully explain the underlying aetiology, which is distinct from that observed in adults. Here, we discuss the differences in cancer genetics, distribution, and microenvironment between adult and pediatric cancers and argue that pediatric tumours need to be seen as a distinct subset with their own distinct therapeutic challenges. While in adults, the benefit of any treatment should outweigh mostly short-term complications, potential long-term effects have a much stronger impact in children. In addition, clinical trials must cope with low participant numbers when evaluating novel treatment strategies, which need to address the specific requirements of children.

Telomere maintenance mechanisms in cancer: telomerase, ALT or lack thereof

Cancer cells acquire replicative immortality by activating a telomere maintenance mechanism (TMM), either the telomerase or the Alternative Lengthening of Telomeres (ALT) mechanism. ALT is frequently activated in tumors derived from mesenchymal cells, which are more frequent in childhood cancers. Recent studies showed that, occasionally, cancer cells can arise without any TMM activation. Here, we discuss the challenge in assessing which TMM is activated in tumors. We also evaluate the prevalence of ALT mechanism in pediatric cancers and review the associated survival prognosis in different tumor types. Finally, we discuss about possible anti-TMM therapies for new emerging cancer treatments.

Prognostic profiling of the immune cell microenvironment in Ewing´s Sarcoma Family of Tumors

Ewing´s Sarcoma Family of Tumors (ESFT) are clinically aggressive bone and soft tissue tumors in children and young adults. Analysis of the immune tumor microenvironment (TME) provides insight into tumor evolution and novel treatment options. So far, the scarcity of immune cells in ESFT has hindered a comprehensive analysis of rare subtypes. We determined the relative fraction of 22 immune cell types using 197 microarray gene expression datasets of primary ESFT tumor samples by using CIBERSORT, a deconvolution algorithm enumerating infiltrating leucocytes in bulk tumor tissue. The most abundant cells were macrophages (mean 43% of total tumor-infiltrating leukocytes, TILs), predominantly immunosuppressive M2 type macrophages, followed by T cells (mean 23% of TILs). Increased neutrophils, albeit at low number, were associated with a poor overall survival (OS) (p = .038) and increased M2 macrophages predicted a shorter event-free survival (EFS) (p = .033). High frequency of T cells and activated NK cells correlated with prolonged OS (p = .044 and p = .007, respectively). A small patient population (9/32) with combined low infiltrating M2 macrophages, low neutrophils, and high total T cells was identified with favorable outcome. This finding was confirmed in a validation cohort of patients with follow up (11/38). When comparing the immune TME with expression of known stemness genes, hypoxia-inducible factor 1 α (HIF1α) correlated with high abundance of macrophages and neutrophils and decreased T cell levels. The immune TME in ESFTs shows a distinct composition including rare immune cell subsets that in part may be due to expression of HIF1α.

Is health status impaired in childhood cancer survivors? A systematic review and meta-analysis

BACKGROUND

An increase in survival rates of childhood cancer is associated with long-term health issues in survivors.

METHODS

We conducted a systematic review and meta-analysis comparing health status-related endpoints in childhood cancer survivors (CCS) versus controls.

RESULTS

Eighty-six studies (n = 98,480 participants, 62% CCS) were included in the review. Of these, 73 studies (n = 96,550, 63% CCS) could be meta-analyzed. CCS showed a lower left ventricular ejection and fractional shortening (SMD=-0.59 and -0.55, respectively, both p < 0.01 [n=1,824 and 1,880]), a lower HDL-cholesterol concentration (SMD=-0.48, p<0.001, n=1,378) and a higher waist-to-hip ratio (SMD=0.61, p < 0.01, n=229) than their healthy peers. No significant differences were found for the remaining endpoints.

CONCLUSIONS

CCS is associated with a lower left ventricular function and HDL-cholesterol level, and a higher waist-to-hip ratio than healthy controls. These findings support the need to closely monitor the cardiometabolic health status of CCS and to implement preventive lifestyle interventions for this population.

Improving the Brain Delivery of Chemotherapeutic Drugs in Childhood Brain Tumors

The central nervous system (CNS) may be considered as a sanctuary site, protected from systemic chemotherapy by the meninges, the cerebrospinal fluid (CSF) and the blood-brain barrier (BBB). Consequently, parenchymal and CSF exposure of most antineoplastic agents following intravenous (IV) administration is lower than systemic exposure. In this review, we describe the different strategies developed to improve delivery of antineoplastic agents into the brain in primary and metastatic CNS tumors. We observed that several methods, such as BBB disruption (BBBD), intra-arterial (IA) and intracavitary chemotherapy, are not routinely used because of their invasiveness and potentially serious adverse effects. Conversely, intrathecal (IT) chemotherapy has been safely and widely practiced in the treatment of pediatric primary and metastatic tumors, replacing the neurotoxic cranial irradiation for the treatment of childhood lymphoma and acute lymphoblastic leukemia (ALL). IT chemotherapy may be achieved through lumbar puncture (LP) or across the Ommaya intraventricular reservoir, which are both described in this review. Additionally, we overviewed pharmacokinetics and toxic aspects of the main IT antineoplastic drugs employed for primary or metastatic childhood CNS tumors (such as methotrexate, cytosine arabinoside, hydrocortisone), with a concise focus on new and less used IT antineoplastic agents.

The genomic landscape of pediatric cancers: Implications for diagnosis and treatment

The past decade has witnessed a major increase in our understanding of the genetic underpinnings of childhood cancer. Genomic sequencing studies have highlighted key differences between pediatric and adult cancers. Whereas many adult cancers are characterized by a high number of somatic mutations, pediatric cancers typically have few somatic mutations but a higher prevalence of germline alterations in cancer predisposition genes. Also noteworthy is the remarkable heterogeneity in the types of genetic alterations that likely drive the growth of pediatric cancers, including copy number alterations, gene fusions, enhancer hijacking events, and chromoplexy. Because most studies have genetically profiled pediatric cancers only at diagnosis, the mechanisms underlying tumor progression, therapy resistance, and metastasis remain poorly understood. We discuss evidence that points to a need for more integrative approaches aimed at identifying driver events in pediatric cancers at both diagnosis and relapse. We also provide an overview of key aspects of germline predisposition for cancer in this age group.