HGG-16. Pediatric-type diffuse high-grade glioma of methylation-based RTK2A and RTK2B subclasses present distinct radiological and histomolecular features [Abstract]

BACKGROUND Diffuse pediatric-type high-grade gliomas (pedHGG), H3-wildtype and IDH-wildtype, encompass three main methylome-based subclasses: pedHGG-MYCN, -RTK1A/B/C, and -RTK2A/B. Since their first description in 2017, tumors of pedHGG-RTK2A/B have not been further characterized and their clinical significance is unknown. METHODS A not yet published cases series on pedHGG with a gliomatosis cerebri (GC) growth pattern showed an increased incidence of pedHGG-RTK2A/B (n=18/40). We assembled a cohort of 14 additional methylation-based pedHGG-RTK2A/B tumors and pooled them with the GC tumors providing centrally reviewed radiological, histological, and molecular characterization. RESULTS Our cohort of 32 pedHGG-RTK2A/B tumors consisted of 25 RTK2A (78%) and seven RTK2B (22%) cases. The median age was 11.6 years (4-17) with an overall survival of 15.9 months (interquartile range 12.1-25.8). Of the additional unselected cases with available imaging (10 of 14), seven showed a GC phenotype at diagnosis or follow-up. In addition, pedHGG-RTK2B tumors exhibited bithalamic involvement (6/7, 86%). Histopathology confirmed a diffuse glial neoplasm in all cases with prominent angiocentric features in both subclasses. Most tumors (24/29, 83%) diffusely expressed EGFR, notably with a focal perivascular enhancement. Cells of pedHGG-RTK2A lacked Olig2 expression, whereas 43% (3/7) of pedHGG-RTK2B expressed Olig2. Loss of ATRX expression occurred in four pedHGG-RTK2B samples (57%). In sequencing analyses (RTK2A: n=18, RTK2B: n=5), EGFR alterations (n=15/23, 65%; predominantly point mutations) were commonly found in both subclasses. Mutations in BCOR (n=14/18, 78%), SETD2 (n=7/18, 39%), and TERT promoter (n=6/18, 33%) occurred exclusively in pedHGG-RTK2A tumors, while pedHGG-RTK2B tumors were enriched for TP53 mutations (4/5, 80%). CONCLUSIONS In conclusion, genotype-phenotype correlations in a multicenter series of pedHGG-RTK2A/B tumors revealed a highly diffuse-infiltrating tumor frequently exhibiting a GC phenotype. The two subclasses share particular histomolecular features (EGFR alterations, angiocentric pattern), whereas they differ in specific characteristics (pedHGG-RTK2A: Olig2 negativity, BCOR and SETD2 mutations; pedHGG-RTK2B: ATRX and TP53 alterations)

Treatment-Related Survival Patterns in Diffuse Intrinsic Pontine Glioma (DIPG) Using a Historical Cohort: A Report from the European Society for Pediatric Oncology DIPG/DMG Registry

Background:Our aim is to investigate the association of treatment with survival in patients with diffuse intrinsic pontine glioma (DIPG), by examining six historical treatment paths.Methods:We retrospectively analyzed data from 409 patients with radiologically centrally reviewed DIPG, sourced from the GPOH HIT-HGG trial database and the SIOPE DIPG/DMG Registry. Survival outcomes were estimated using the Kaplan Meier method and univariable and multivariable Cox proportional hazard models were estimated to study treatment effect.Results:Median overall survival (OS) from diagnosis was 11.2 months (95% CI, 10.5-11.9). Patients who by choice received no frontline treatment had an OS of 3.0 months (95% CI, 2.0-4.0), while those treated with radiation therapy (RT) alone had a median OS of 10.4 months (95% CI, 9.1-11.8). Those receiving RT combined with chemotherapy had the longest median OS of 11.7 months (95% CI, 10.8-12.6). Median survival after first progression (PPS) was 4.1 months (95% CI, 3.5-4.7). Patients who relapsed and did not receive treatment had a PPS of 2.2 months (95% CI, 1.8-2.6), while those treated with chemotherapy alone had a PPS of 4.4 months (95% CI, 3.7-5.0), and those who underwent reirradiation, with or without chemotherapy, had the longest survival after relapse of 6.6 months (95% CI, 5.3-8.0). Treatment differences remained significant in multivariable analysis adjusted for age and symptom duration, in both the diagnosis and relapse setting.Conclusions:This study shows increased survival outcomes associated with radio- and chemotherapy treatment or a combination thereof, at diagnosis and relapse, in a historical DIPG cohort

Identification of pyrazolopyridazinones as PDEδ inhibitors

The prenyl-binding protein PDEδ is crucial for the plasma membrane localization of prenylated Ras. Recently, we have reported that the small-molecule Deltarasin binds to the prenyl-binding pocket of PDEδ, and impairs Ras enrichment at the plasma membrane, thereby affecting the proliferation of KRas-dependent human pancreatic ductal adenocarcinoma cell lines. Here, using structure-based compound design, we have now identified pyrazolopyridazinones as a novel, unrelated chemotype that binds to the prenyl-binding pocket of PDEδ with high affinity, thereby displacing prenylated Ras proteins in cells. Our results show that the new PDEδ inhibitor, named Deltazinone 1, is highly selective, exhibits less unspecific cytotoxicity than the previously reported Deltarasin and demonstrates a high correlation with the phenotypic effect of PDEδ knockdown in a set of human pancreatic cancer cell lines

How I treat recurrent pediatric high-grade glioma (pHGG): a Europe-wide survey study

Abstract Purpose As there is no standard of care treatment for recurrent/progressing pediatric high-grade gliomas (pHGG), we aimed to gain an overview of different treatment strategies. Methods In a web-based questionnaire, members of the SIOPE-BTG and the GPOH were surveyed on therapeutic options in four case scenarios (children/adolescents with recurrent/progressing HGG). Results 139 clinicians with experience in pediatric neuro-oncology from 22 European countries participated in the survey. Most respondents preferred further oncological treatment in three out of four cases and chose palliative care in one case with marked symptoms. Depending on the case, 8–92% would initiate a re-resection (preferably hemispheric pHGG), combined with molecular diagnostics. Throughout all case scenarios, 55–77% recommended (re-)irradiation, preferably local radiotherapy > 20 Gy. Most respondents would participate in clinical trials and use targeted therapy (79–99%), depending on molecular genetic findings ( BRAF alterations: BRAF/MEK inhibitor, 64–88%; EGFR overexpression: anti-EGFR treatment, 46%; CDKN2A deletion: CDK inhibitor, 18%; S MARCB1 deletion: EZH2 inhibitor, 12%). 31–72% would administer chemotherapy (CCNU, 17%; PCV, 8%; temozolomide, 19%; oral etoposide/trofosfamide, 8%), and 20–69% proposed immunotherapy (checkpoint inhibitors, 30%; tumor vaccines, 16%). Depending on the individual case, respondents would also include bevacizumab (6–18%), HDAC inhibitors (4–15%), tumor-treating fields (1–26%), and intraventricular chemotherapy (4–24%). Conclusion In each case, experts would combine conventional multimodal treatment concepts, including re-irradiation, with targeted therapy based on molecular genetic findings. International cooperative trials combining a (chemo-)therapy backbone with targeted therapy approaches for defined subgroups may help to gain valid clinical data and improve treatment in pediatric patients with recurrent/progressing HGG.Styrian Childhood Cancer FoundationMedical University of Graz 50110001010

Combined treatment with CBP and BET inhibitors reverses inadvertent activation of detrimental super enhancer programs in DIPG cells

Abstract Diffuse intrinsic pontine gliomas (DIPG) are the most aggressive brain tumors in children with 5-year survival rates of only 2%. About 85% of all DIPG are characterized by a lysine-to-methionine substitution in histone 3, which leads to global H3K27 hypomethylation accompanied by H3K27 hyperacetylation. Hyperacetylation in DIPG favors the action of the Bromodomain and Extra-Terminal (BET) protein BRD4, and leads to the reprogramming of the enhancer landscape contributing to the activation of DIPG super enhancer-driven oncogenes. The activity of the acetyltransferase CREB-binding protein (CBP) is enhanced by BRD4 and associated with acetylation of nucleosomes at super enhancers (SE). In addition, CBP contributes to transcriptional activation through its function as a scaffold and protein bridge. Monotherapy with either a CBP (ICG-001) or BET inhibitor (JQ1) led to the reduction of tumor-related characteristics. Interestingly, combined treatment induced strong cytotoxic effects in H3.3K27M-mutated DIPG cell lines. RNA sequencing and chromatin immunoprecipitation revealed that these effects were caused by the inactivation of DIPG SE-controlled tumor-related genes. However, single treatment with ICG-001 or JQ1, respectively, led to activation of a subgroup of detrimental super enhancers. Combinatorial treatment reversed the inadvertent activation of these super enhancers and rescued the effect of ICG-001 and JQ1 single treatment on enhancer-driven oncogenes in H3K27M-mutated DIPG, but not in H3 wild-type pedHGG cells. In conclusion, combinatorial treatment with CBP and BET inhibitors is highly efficient in H3K27M-mutant DIPG due to reversal of inadvertent activation of detrimental SE programs in comparison with monotherapy.Open-Access-Publikationsfonds 202

Boswellic acid formulations are not suitable for treatment of pediatric high-grade glioma due to tumor promoting potential

Background and aim: Pediatric high-grade gliomas (pedHGG) comprise a very poor prognosis. Thus, parents of affected children are increasingly resorting to complementary and alternative medicine (CAM), among those Boswellia extracts. However, nothing is known about the therapeutic effectiveness of their active substances, Boswellic acids (BA) in pedHGG. Thus, we aimed to investigate if the three main Boswellic acids (BA) present in Boswellia plants, alpha-boswellic acid (α-BA), beta-boswellic acid (β-BA) and 3-acetyl-11-keto-beta-boswellic acid (AKBA) hold any promising potential for treatment of affected pedHGG patients. Experimental procedure: Histone 3 (H3)-wildtype and H3.3K27M-mutant pedHGG cell lines were treated with BA, either alone or in combination with radio-chemotherapy with temozolomide. Cell viability, stemness properties, apoptosis, in ovo tumor growth and the transcriptome was investigated upon BA treatment. Results and conclusion: Interestingly, α-BA and β-BA treatment promoted certain tumor properties in both pedHGG cells. AKBA treatment reduced cell viability and colony growth accompanied by induction of slight anti-inflammatory effects especially in H3.3K27M-mutant pedHGG cells. However, no effects on apoptosis and in ovo tumor growth were found. In conclusion, besides positive anti-tumor effects of AKBA, tumor promoting effects were observed upon treatment with α-BA and β-BA. Thus, only pure AKBA formulations may be used to exploit any potential positive effects in pedHGG patients. In conclusion, the use of commercially available supplements with a mixture of different BA cannot be recommended due to detrimental effects of certain BA whereas pure AKBA formulations might hold some potential as therapeutic supplement for treatment of pedHGG patients

Dual Inhibition of GSK3β and CDK5 Protects the Cytoskeleton of Neurons from Neuroinflammatory-Mediated Degeneration In Vitro and In Vivo

Summary: Neuroinflammation is a hallmark of neurological disorders and is accompanied by the production of neurotoxic agents such as nitric oxide. We used stem cell-based phenotypic screening and identified small molecules that directly protected neurons from neuroinflammation-induced degeneration. We demonstrate that inhibition of CDK5 is involved in, but not sufficient for, neuroprotection. Instead, additional inhibition of GSK3β is required to enhance the neuroprotective effects of CDK5 inhibition, which was confirmed using short hairpin RNA-mediated knockdown of CDK5 and GSK3β. Quantitative phosphoproteomics and high-content imaging demonstrate that neurite degeneration is mediated by aberrant phosphorylation of multiple microtubule-associated proteins. Finally, we show that our hit compound protects neurons in vivo in zebrafish models of motor neuron degeneration and Alzheimer's disease. Thus, we demonstrate an overlap of CDK5 and GSK3β in mediating the regulation of the neuronal cytoskeleton and that our hit compound LDC8 represents a promising starting point for neuroprotective drugs. : Neuroinflammation is a hallmark of many neurological disorders and can be neurotoxic. Sterneckert and colleagues perform a phenotypic screening campaign identifying compounds protecting motor neurons from inflammation. Compound profiling demonstrates that dual inhibition of CDK5 and GSK3β mediates neuroprotection. Quantitative phosphoproteomics demonstrates that neuroprotection is linked to alterations in microtubule dynamics mediated by phosphorylation of microtubule-associated proteins. Keywords: neurodegeneration, neuroinflammation, stem cell-based phenotypic screening, CDK5, GSK3β, induced pluripotent stem cells, AL

General support of physical exercise programs in pediatric oncology but differences in perception by childhood cancer care professionals at European and North-African/Arab centers

Purpose: To explore the perception of physical exercise programs for pediatric oncology patients among childhood cancer care professionals. We also aimed at comparing such perceptions between cultures. Healthcare professionals’ endorsement may be essential for initiating and promoting such programs. Methods: An anonymous survey was designed and administered voluntarily to childhood cancer care professionals (including pediatric oncologists, nurses, and physiotherapists) in European, North-African and Arab pediatric oncology centers. Results: Five-hundred-and twenty-eight professionals from 14 sites answered the survey. Most respondents considered physical exercise programs as a suitable therapeutic approach for pediatric cancer patients with a potential positive contribution to survival (81%), wellbeing (82%), quality of life (80%), and self-esteem (75%). 91% of respondents would also support the future introduction of physical exercise programs into standard pediatric oncological care. There was a comparatively higher appreciation of physical exercise programs among European centers compared to North-African / Arab centers. Conclusion: We registered a broad acceptance of physical exercise programs among all European and North-African / Arab childhood cancer care professionals. The positive perception was independent of any pre-existing experience with such programs and seems therefore representative. This finding may encourage the further promotion of physical exercise programs in pediatric oncology

Pediatric high-grade gliomas and the WHO CNS Tumor Classification - Perspectives of pediatric neuro-oncologists and neuropathologists in light of recent updates

Background: The WHO Classification of Tumors of the Central Nervous System has undergone major restructuring. Molecularly defined diagnostic criteria were introduced in 2016 (revised 4th edition) and expanded in 2021 (5th edition) to incorporate further essential diagnostic molecular parameters. We investigated potential differences between specialists in perception of these molecularly defined subtypes for pediatric high-grade gliomas (pedHGG). Methods: We designed a 22-question survey studying the impact of the revised 4th edition of the WHO classification on pedHGG. Data were collected and statistically analyzed to examine the spectrum of viewpoints and possible differences between neuro-oncologists and neuropathologists. Results: 465 participants from 53 countries were included; 187 pediatric neuro-oncologists (40%), 160 neuropathologists (34%), and 118 additional experts (26%). Neuro-oncologists reported issues with the introduction of molecularly defined tumor types, as well as the abolishment or renaming of established tumor entities, while neuropathologists did not to the same extent. Both groups indicated less relevant or insufficient diagnostic definitions were available in 2016. Reported issues were classified and assessed in the 2021 WHO classification and a substantial improvement was perceived. However, issues of high clinical relevance remain to be addressed, including the definition of clinical phenotypes for diffuse intrinsic pontine glioma and gliomatosis cerebri. Conclusions: Within the WHO classification of pediatric brain tumors, such as pedHGG, rapid changes in molecular characterization have been introduced. This study highlights the ongoing need for cross talk between pathologist and oncologist to advance the classification of pedHGG subtypes and ensure biological relevance and clinical impact