Childhood brain tumors: current management, biological insights, and future directions

IL1RAP regulated by PRPRD promotes gliomas progression via inducing neuronal synapse development and neuron differentiation in vitro

BACKGROUND

Glioma is a common fatal brain tumor that affects the central nervous system of the brain and spinal cord.

METHODS

This is an original research. The morphology of M059 J cells and U373 cells were detected by microscope, cell neurite outgrowth was observed by immunofluorescence, and the expression of PRPRD and its downstream genes in HMC3 cells, M059 J cells and U373 cells were evaluated and compared with flow cytometry, immunofluorescence and Western blotting assay.

RESULTS

Here we show that the expression of FBP17 on the surface of glioma cells M059 J and U373 cells is more than normal cells. Overexpression of protein tyrosine phosphatase receptor-δ (PTPRD) in M059 J and U373 cells resulted in a significant increase in the S phase of the cells, while the G2 phase of the cells decreased significantly after interference with PTPRD. And PTPRD protein is mainly distributed in HMC3 cells, M059 J and U373 cytoplasm. Moreover, overexpression of PTPRD resulted in a significant increase in the expression of interleukin 1 receptor accessory protein (IL1RAP), PPFIA1 and SLITRK2, and these genes were significantly suppressed after interference with PTPRD.

CONCLUSION

This study shows that PRPRD can be used as a potential biomarker for glioma treatment. These results indicate that the PRPRD protein affects the development of neuronal synapses and neuronal differentiation by regulating IL1RAP, thereby promoting the progression of gliomas, indicating that PRPRD can be used as a potential biomarker for the treatment of gliomas.

Pediatric cancer mortality and survival in the United States, 2001-2016

BACKGROUND

Although pediatric cancer mortality and survival have improved in the United States over the past 40 years, differences exist by age, race/ethnicity, cancer site, and economic status. To assess progress, this study examined recent mortality and survival data for individuals younger than 20 years.

METHODS

Age-adjusted death rates were calculated with the National Vital Statistics System for 2002-2016. Annual percent changes (APCs) and average annual percent changes (AAPCs) were calculated with joinpoint regression. Five-year relative survival was calculated on the basis of National Program of Cancer Registries data for 2001-2015. Death rates and survival were estimated overall and by sex, 5-year age group, race/ethnicity, cancer type, and county-based economic markers.

RESULTS

Death rates decreased during 2002-2016 (AAPC, -1.5), with steeper declines during 2002-2009 (APC, -2.6), and then plateaued (APC, -0.4). Leukemia and brain cancer were the most common causes of death from pediatric cancer, and brain cancer surpassed leukemia in 2011. Death rates decreased for leukemia and lymphoma but were unchanged for brain, bone, and soft-tissue cancers. From 2001-2007 to 2008-2015, survival improved from 82.0% to 85.1%. Survival was highest in both periods among females, those aged 15 to 19 years, non-Hispanic Whites, and those in counties in the top 25% by economic status. Survival improved for leukemias, lymphomas, and brain cancers but plateaued for bone and soft-tissue cancers.

CONCLUSIONS

Although overall death rates have decreased and survival has increased, differences persist by sex, age, race/ethnicity, cancer type, and economic status. Improvements in pediatric cancer outcomes may depend on improving therapies, access to care, and supportive and long-term care.

Targeting Sphingosine Kinase by ABC294640 against Diffuse Intrinsic Pontine Glioma (DIPG)

As a highly aggressive pediatric brainstem tumor, diffuse intrinsic pontine glioma (DIPG) accounts for 10% to 20% of childhood brain tumors. The survival rate for DIPG remains very low, with a median survival time as less than one year even under radiotherapy, the current standard treatment. Moreover, over than 250 clinical trials have failed when trying to improve the survival compared to radiotherapy. The sphingolipid metabolism and related signaling pathways have been found closely related to cancer cell survival; however, the sphingolipid metabolism targeted therapies have never been investigated in DIPG. In the current study, the anti-DIPG activity of ABC294640, the only first-in-class orally available Sphingosine kinase (SphK) inhibitor was explored. Treatment with ABC294640 significantly repressed DIPG cell growth by inducing intracellular pro-apoptotic ceramides production and cell apoptosis. We also profiled ABC294640-induced changes in gene expression within DIPG cells and identified many new genes tightly controlled by sphingolipid metabolism, such as IFITM1 and KAL1. These genes are required for DIPG cell survival and display clinical relevance in DIPG patients' samples. Together, our findings in this study indicate that targeting sphingolipid metabolism may represent a promising strategy to improve DIPG treatment.

PTPmu-targeted nanoparticles label invasive pediatric and adult glioblastoma

Poor prognosis for glioblastoma (GBM) is a consequence of the aggressive and infiltrative nature of gliomas where individual cells migrate away from the main tumor to distant sites, making complete surgical resection and treatment difficult. In this manuscript, we characterize an invasive pediatric glioma model and determine if nanoparticles linked to a peptide recognizing the GBM tumor biomarker PTPmu can specifically target both the main tumor and invasive cancer cells in adult and pediatric glioma models. Using both iron and lipid-based nanoparticles, we demonstrate by magnetic resonance imaging, optical imaging, histology, and iron quantification that PTPmu-targeted nanoparticles effectively label adult gliomas. Using PTPmu-targeted nanoparticles in a newly characterized orthotopic pediatric SJ-GBM2 model, we demonstrate individual tumor cell labeling both within the solid tumor margins and at invasive and dispersive sites.

Immunotherapy for Medulloblastoma: Current Perspectives

Background

Immune-mediated therapies have transformed the treatment of metastatic melanoma and renal, bladder, and both small and non-small cell lung carcinomas. However, immunotherapy is yet to demonstrate dramatic results in brain tumors like medulloblastoma for a variety of reasons. Recent pre-clinical and early phase human trials provide encouraging results that may overcome the challenges of central nervous system (CNS) tumors, which include the intrinsic immunosuppressive properties of these cancers, a lack of antigen targets, antigenic variability, and the immune-restrictive site of the CNS. These studies highlight the growing potential of immunotherapy to treat patients with medulloblastoma, a disease that is a frequent cause of morbidity and mortality to children and young adults.

Methods

We conducted an inclusive review of the PubMed-indexed literature and studies listed in clinicaltrials.gov using combinations of the keywords medulloblastoma, immunotherapy, CNS tumors, brain tumors, vaccines, oncolytic virus, natural killer, and CAR T to identify trials evaluating immunotherapy in preclinical experiments or in patients with medulloblastoma. Given a limited number of investigations using immunotherapy to treat patients with medulloblastoma, 24 studies were selected for final analysis and manuscript citation.

Results

This review presents results from pre-clinical studies in medulloblastoma cell lines, animal models, and the limited trials involving human patients.

Conclusion

From our review, we suggest that cancer vaccines, oncolytic viral therapy, natural killer cells, and CAR T therapy hold promise against the innate immunosuppressive properties of medulloblastoma in order to prolong survival. There is an unmet need for immunotherapy regimens that target overexpressed antigens in medulloblastoma tumors. We advocate for more combination treatment clinical trials using conventional surgical and radiochemotherapy approaches in the near-term clinical development.

PET imaging of medulloblastoma with an 18F-labeled tryptophan analogue in a transgenic mouse model

In vivo positron emission tomography (PET) imaging is a key modality to evaluate disease status of brain tumors. In recent years, tremendous efforts have been made in developing PET imaging methods for pediatric brain tumors. Carbon-11 labelled tryptophan derivatives are feasible as PET imaging probes in brain tumor patients with activation of the kynurenine pathway, but the short half-life of carbon-11 limits its application. Using a transgenic mouse model for the sonic hedgehog (Shh) subgroup of medulloblastoma, here we evaluated the potential of the newly developed 1-(2-[¹⁸F]fluoroethyl)-L-tryptophan (1-L-[¹⁸F]FETrp) as a PET imaging probe for this common malignant pediatric brain tumor. 1-L-[¹⁸F]FETrp was synthesized on a PETCHEM automatic synthesizer with good chemical and radiochemical purities and enantiomeric excess values. Imaging was performed in tumor-bearing Smo/Smo medulloblastoma mice with constitutive actvation of the Smoothened (Smo) receptor using a PerkinElmer G4 PET-X-Ray scanner. Medulloblastoma showed significant and specific accumulation of 1-L-[¹⁸F]FETrp. 1-L-[¹⁸F]FETrp also showed significantly higher tumor uptake than its D-enantiomer, 1-D-[¹⁸F]FETrp. The uptake of 1-L-[¹⁸F]FETrp in the normal brain tissue was low, suggesting that 1-L-[¹⁸F]FETrp may prove a valuable PET imaging probe for the Shh subgroup of medulloblastoma and possibly other pediatric and adult brain tumors.

Comparative Molecular Life History of Spontaneous Canine and Human Gliomas

Sporadic gliomas in companion dogs provide a window on the interaction between tumorigenic mechanisms and host environment. We compared the molecular profiles of canine gliomas with those of human pediatric and adult gliomas to characterize evolutionarily conserved mammalian mutational processes in gliomagenesis. Employing whole-genome, exome, transcriptome, and methylation sequencing of 83 canine gliomas, we found alterations shared between canine and human gliomas such as the receptor tyrosine kinases, TP53 and cell-cycle pathways, and IDH1 R132. Canine gliomas showed high similarity with human pediatric gliomas per robust aneuploidy, mutational rates, relative timing of mutations, and DNA-methylation patterns. Our cross-species comparative genomic analysis provides unique insights into glioma etiology and the chronology of glioma-causing somatic alterations.

Clinical trials for diffuse intrinsic pontine glioma: the current state of affairs

PURPOSE

Diffuse intrinsic pontine glioma (DIPG) is a lethal high-grade pediatric brainstem tumor without a cure. Despite numerous clinical trials over the last decades, the prognosis has remained poor. The aim of this update was to report on the status and outcomes of all clinical trials for DIPG performed to better understand the landscape of research efforts for this diagnosis to date.

METHODS

The ClinicalTrials.gov database was reviewed in May 2019 for all possible interventional clinical trials that included DIPG as a diagnosis of primary investigation. These were then screened against selection criteria to identify pertinent clinical trials.

RESULTS

Ninety-five clinical trials satisfied all inclusion criteria, with 55 (58%) trials specific to the DIPG diagnosis only. In terms of the most prevalent design features, 42 (44%) were phase I trials, with median expected start and completion years in 2011 (range, 1994-2020) and 2018 (range, 2005-2047), respectively. Median target number of patients to enroll was 38 (range, 1-1500), and the most common primary outcome was safety and toxicity (56%). There were 69 (73%) trials originating from the USA, with 49 (52%) of them being single institutional. Only 10 (11%) trials have reported results to date.

CONCLUSIONS

To date, 95 clinical trials investigating DIPG with specific emphasis have been registered on ClinicalTrials.gov. There were only a small number of trials that had study results available, and they uniformly reported non-significant improvement to prognosis. Given the rarity and lethality of DIPG, which limits the accumulation of large cohorts, our results mandate the need for more robust, systematic clinical trial design to minimize redundancies and maximize yield in the future.

Overview of Current Drug Delivery Methods Across the Blood-Brain Barrier for the Treatment of Primary Brain Tumors

Existing drug delivery methods have not led to a significant increase in survival for patients with malignant primary brain tumors. While the combination of conventional therapies consisting of surgery, radiotherapy, and chemotherapy has improved survival for some types of brain tumors (e.g., WNT medulloblastoma), other types of brain tumors (e.g., glioblastoma and diffuse midline glioma) still have a poor prognosis. The reason for the differences in response can be largely attributed to the blood-brain barrier (BBB), a specialized structure at the microvasculature level that regulates the transport of molecules across the blood vessels into the brain parenchyma. This structure hampers the delivery of most chemotherapeutic agents for the treatment of primary brain tumors. Several drug delivery methods such as nanoparticles, convection enhanced delivery, focused ultrasound, intranasal delivery, and intra-arterial delivery have been developed to overcome the BBB in primary brain tumors. However, prognosis of most primary brain tumors still remains poor. The heterogeneity of the BBB in primary brain tumors and the distinct vasculature of tumors make it difficult to design a drug delivery method that targets the entire tumor. Drug delivery methods that combine strategies such as focused ultrasound and nanoparticles might be a more successful approach. However, more research is needed to optimize and develop new drug delivery techniques to improve survival of patients with primary brain tumors.

BRAF V600E Detection in Liquid Biopsies from Pediatric Central Nervous System Tumors

Pediatric Central Nervous System (CNS) tumors are the most fatal cancer diseases in childhood. Due to their localization and infiltrative nature, some tumor resections or biopsies are not feasible. In those cases, the use of minimally invasive methods as diagnostic, molecular marker detection, prognostic or monitoring therapies are emerging. The analysis of liquid biopsies which contain genetic information from the tumor has been much more widely explored in adults than in children. We compare the detection of BRAF V600E targetable mutation by digital-PCR from cell-free-DNA and EV-derived DNA (ctDNA) in serum, plasma and cerebrospinal fluid (CSF) isolated from a cohort of 29 CNS pediatric patients. Here we demonstrate that ctDNA isolated from serum and plasma could be successfully analyzed to obtain tumor genetic information which could be used to guide critical treatment decisions.

Childhood medulloblastoma-a single institution's historical perspective on survival and functional morbidity

PURPOSE

To compare results from a third (1995-2010) cohort of children with medulloblastoma with two previous series (J Neurosurg 86:13-21, 1997; Arch Dis Child 54:200-203, 1979) to analyse the effects of management changes aimed at improving both overall and event-free survivals (OS and EFS) and functional outcomes.

METHODS

Review of neuro-oncology and imaging databases and previously published results.

RESULTS

There was no statistically significant improvement in the 5-year OS for 104 children diagnosed 1995-2010, 61.5% (95% CI, 52.9, 71.6), compared with 50% of the 80 children presenting 1980-1990 (J Neurosurg 86:13-21, 1997) (difference 11.5%; 95% CI, 2.8, 25.4). Five-year OS for 96 children suitable for risk-stratification was overall 66% (95% CI, 57.9, 75.8); standard risk 77.8% (95% CI, 67.4, 89.7); high risk < 3 years 50.0% (95% CI, 32.3, 77.5); high risk ≥ 3 years 54.5% (95% CI, 37.2, 79.9); 5-year EFS were standard risk 68.5% (95% CI, 57.2, 82.1); high risk < 3 years 40.0% (95% CI, 23.4, 68.4); and high risk ≥ 3 years 36.4% (95% CI, 20.9, 63.2); overall 55.2% (95% CI, 46.1, 66.1). Of 62/63 ≥ 5-year survivor, 9 died later from tumour relapse and 4 from second malignancy. Functional outcomes of 62 of the 63 ≥ 5-year survivors: 67.7% had educational issues requiring remedial input; 18% restricted mobility indoors and outdoors; 59.7% hearing impairment (42% prescribed aids).

CONCLUSIONS

1. Comparison of this single-institution series with its predecessor found that revised chemotherapy and RT protocols and greater accuracy of risk stratification did not result in statistically significant improvements in either survival or treatment-related functional disability. 2. Extended (> 5-year) follow-up is essential if 20% of late deaths from relapse and second malignancies are not to be overlooked.

PATZ1 Is Overexpressed in Pediatric Glial Tumors and Correlates with Worse Event-Free Survival in High-grade Gliomas

Glial tumors are the leading cause of cancer-related death and morbidity in children. Their diagnosis, mainly based on clinical and histopathological factors, is particularly challenging because of their high molecular heterogeneity. Thus, tumors with identical histotypes could result in variable biological behaviors and prognoses. The PATZ1 gene has been recently shown to be expressed in adult gliomas, including glioblastomas, where it correlates with the proneural subtype and with a better prognosis. Here, we analyzed the expression of PATZ1 in pediatric gliomas, first at mRNA level in a public database, and then at protein level, by immunohistochemistry, in a cohort of 52 glial brain tumors from young patients aged from 6 months to 16 years. As for adult tumors, we show that PATZ1 is enriched in glial tumors compared to the normal brain, where it correlates positively and negatively with a proneural and mesenchymal signature, respectively. Moreover, we show that PATZ1 is expressed at variable levels in our cohort of tumors. Higher expression was detected in high-grade than low-grade gliomas, suggesting a correlation with the malignancy. Among high-grade gliomas, higher levels of PATZ1 have consistently been found to correlate with worse event-free survival. Therefore, our study may imply new diagnostic opportunities for pediatric gliomas.

CAR T cells for brain tumors: Lessons learned and road ahead

Malignant brain tumors, including glioblastoma, represent some of the most difficult to treat of solid tumors. Nevertheless, recent progress in immunotherapy, across a broad range of tumor types, provides hope that immunological approaches will have the potential to improve outcomes for patients with brain tumors. Chimeric antigen receptors (CAR) T cells, a promising immunotherapeutic modality, utilizes the tumor targeting specificity of any antibody or receptor ligand to redirect the cytolytic potency of T cells. The remarkable clinical response rates of CD19-targeted CAR T cells and early clinical experiences in glioblastoma demonstrating safety and evidence for disease modifying activity support the potential of further advancements ultimately providing clinical benefit for patients. The brain, however, is an immune specialized organ presenting unique and specific challenges to immune-based therapies. Remaining barriers to be overcome for achieving effective CAR T cell therapy in the central nervous system (CNS) include tumor antigenic heterogeneity, an immune-suppressive microenvironment, unique properties of the CNS that limit T cell entry, and risks of immune-based toxicities in this highly sensitive organ. This review will summarize preclinical and clinical data for CAR T cell immunotherapy in glioblastoma and other malignant brain tumors, including present obstacles to advancement.