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Background: Diffuse midline glioma, characterised by H3K27 alteration (DMG), is the predominant high-grade glioma in children. It commonly originates in the brainstem, yet effective treatments for these patients remain elusive., Methods: To identify novel therapies for DMG, we conducted high-throughput drug screens (HTS) using biologically active, clinically approved compounds against DMG neurospheres. Multiple primary DMG cultures were utilised in conjunction with in vitro cytotoxicity and clonogenic assays to validate the efficacy of top compounds. Molecularly diverse patient-derived and transgenic DMG orthotopic models were employed to assess therapeutic efficacy alongside pharmacokinetic and immunohistochemical analyses. Mechanistic studies, including RNA sequencing, western blotting, and flow cytometry, were conducted to elucidate the antitumour efficacy of the most promising compound, fenretinide, in DMG cells., Results: Through HTS, six compounds were identified and validated for their potent cytotoxic activity. However, most of these compounds failed to improve survival in an orthotopic Diffuse Midline Glioma (DMG) model due to limited blood-brain barrier (BBB) penetration. In contrast, fenretinide exhibited effective BBB penetration, significantly enhancing the survival of tumour-bearing animals. Mechanistic studies revealed that fenretinide increased reactive oxygen species (ROS) generation and induced apoptosis by inhibiting PDGFRα. RNA-sequencing further elucidated that fenretinide upregulates the Unfolded Protein Response (UPR) and endoplasmic reticulum (ER) stress pathways while downregulating neurogenesis. The in vivo antitumour efficacy of two fenretinide formulations was demonstrated in PDGFRα-amplified and transgenic DMG models., Conclusion: This comprehensive study has identified new DMG therapeutic vulnerabilities and highlights fenretinide as a brain-penetrant, anti-DMG agent., (© The Author(s) 2025. Published by Oxford University Press on behalf of the Society for Neuro-Oncology.)

Background: Diffuse intrinsic pontine gliomas (DIPGs) pose a significant challenge as a highly aggressive and currently incurable form of pediatric brain cancer, necessitating the development of novel therapeutic strategies. Omacetaxine, an FDA-approved protein synthesis inhibitor for treating certain hematological malignancies, was investigated for its potential antitumor effects against preclinical DIPG models., Methods: We employed primary DIPG cultures to study omacetaxine's cytotoxicity and its impact on colony formation. Annexin V staining and flow cytometry assessed apoptosis. Wound healing assays evaluated migration, while western blotting determined inhibition of oncogenic proteins. We tested omacetaxine's therapeutic efficacy in an orthotopic DIPG model and assessed brain penetration using mass spectrometry., Results: We found a pronounced cytotoxic activity of omacetaxine against DIPG neurospheres, with low IC 50 values of approximately 20 nM. Omacetaxine exerted its anti-proliferative effect by inhibiting protein synthesis and the induction of apoptotic pathways, evidenced by significant elevated levels of cleaved caspase 3 and cleaved PARP, both key markers of apoptosis. Omacetaxine effectively targeted oncogenic players such as PDGFRα and PI3K without additional effects on the mTOR signaling pathway. Furthermore, our study revealed the inhibitory effects of omacetaxine on cell migration, and a significant reduction in integrin/FAK signaling, which plays a crucial role in tumor progression and metastasis., Conclusions: Despite these promising in vitro effects, omacetaxine's efficacy in an orthotopic DIPG model was limited due to inadequate penetration across the blood-brain barrier. As such, further research and advancements are crucial to improve the drug's brain penetration, thus enhancing its overall therapeutic potential., Competing Interests: D.S.Z. reports consulting/advisory board fees from Bayer, Astra Zeneca, Accendatech, Novartis, Day One, FivePhusion, Amgen, Alexion, and Norgine and research support from Accendatech., (© The Author(s) 2024. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)

Diffuse intrinsic pontine glioma (DIPG) is an aggressive and incurable childhood brain tumor for which new treatments are needed. CBL0137 is an anti-cancer compound developed from quinacrine that targets facilitates chromatin transcription (FACT), a chromatin remodeling complex involved in transcription, replication, and DNA repair. We show that CBL0137 displays profound cytotoxic activity against a panel of patient-derived DIPG cultures by restoring tumor suppressor TP53 and Rb activity. Moreover, in an orthotopic model of DIPG, treatment with CBL0137 significantly extends animal survival. The FACT subunit SPT16 is found to directly interact with H3.3K27M, and treatment with CBL0137 restores both histone H3 acetylation and trimethylation. Combined treatment of CBL0137 with the histone deacetylase inhibitor panobinostat leads to inhibition of the Rb/E2F1 pathway and induction of apoptosis. The combination of CBL0137 and panobinostat significantly prolongs the survival of mice bearing DIPG orthografts, suggesting a potential treatment strategy for DIPG., Competing Interests: Declaration of interests K.G. and A.V.G. are co-inventors on patents describing CBL0137. The remaining authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: There are limited data to predict which novel childhood cancer therapies are likely to be successful. To help rectify this, we sought to identify the factors that impact the success of phase II clinical trials for pediatric malignancies., Materials and Methods: We examined the impact of 24 preclinical and trial design variables for their influence on 132 phase II pediatric oncology clinical trials. Success was determined by an objective assessment of patient response, with data analyzed using Fisher's exact test, Pearson's chi-square test, and logistic regression models., Results: Trials that evaluated patients with a single histological cancer type were more successful than those that assessed multiple different cancer types (68% vs. 47%, 27%, and 17% for 1, 2-3, 4-7, and 8+; p  < .005). Trials on liquid or extracranial solid tumors were more successful than central nervous system or combined trials (70%, 60%, 38%, and 24%; p  < .005), and trials of combination therapies were more successful than single agents (71% vs. 28%; p  < .005). Trials that added therapies to standard treatment backbones were more successful than trials testing novel therapies alone or those that incorporated novel agents ( p  < .005), and trials initiated based on the results of adult studies were less likely to succeed ( p  < .05). For 61% of trials (80/132), we were unable to locate any relevant preclinical findings to support the trial. When preclinical studies were carried out (52/132), there was no evidence that the conduct of any preclinical experiments made the trial more likely to succeed ( p  < .005)., Conclusion: Phase II pediatric oncology clinical trials that examine a single cancer type and use combination therapies have the highest possibility of clinical success. Trials building upon a standard treatment regimen were also more successful. The conduct of preclinical experiments did not improve clinical success, emphasizing the need for a better understanding of the translational relevance of current preclinical testing paradigms., Implications for Practice: To improve the clinical outcomes of phase II childhood cancer trials, this study identified factors impacting clinical success. These results have the potential to impact not only the design of future clinical trials but also the assessment of preclinical studies moving forward. This work found that trials on one histological cancer type and trials testing combination therapies had the highest possibility of success. Incorporation of novel therapies into standard treatment backbones led to higher success rates than testing novel therapies alone. This study found that most trials had no preclinical evidence to support initiation, and even when preclinical studies were available, they did not result in improved success., Competing Interests: Disclosures of potential conflicts of interest may be found at the end of this article., (© AlphaMed Press 2019.)

Purpose: Diffuse intrinsic pontine glioma is the most aggressive form of high grade glioma in children with no effective therapies. There have been no improvements in survival in part due poor understanding of underlying biology, and lack of representative in vitro and in vivo models. Recently, it has been found feasible to use both biopsy and autopsy tumors to generate cultures and xenograft models., Methods: To further model development, we evaluated the collective international experience from 8 collaborating centers to develop DIPG pre-clinical models from patient-derived autopsies and biopsies. Univariate and multivariate analysis was performed to determine key factors associated with the success of in vitro and in vivo PDX development., Results: In vitro cultures were successfully established from 57% of samples (84.2% of biopsies and 38.2% of autopsies). Samples transferred in DMEM media were more likely to establish successful culture than those transported in Hibernate A. In vitro cultures were more successful from biopsies (84.2%) compared with autopsies (38.2%) and as monolayer on laminin-coated plates than as neurospheres. Primary cultures successfully established from autopsy samples were more likely to engraft in animal models than cultures established from biopsies (86.7% vs. 47.4%). Collectively, tumor engraftment was more successful when DIPG samples were directly implanted in mice (68%), rather than after culturing (40.7%)., Conclusion: This multi-center study provides valuable information on the success rate of establishing patient-derived pre-clinical models of DIPG. The results can lead to further optimization of DIPG model development and ultimately assist in the investigation of new therapies for this aggressive pediatric brain tumor.

Pediatric high grade gliomas (HGG) are primary brain malignancies that result in significant morbidity and mortality. One of the challenges in their treatment is inter- and intra-tumoral heterogeneity. Precision medicine approaches have the potential to enhance diagnostic, prognostic and/or therapeutic information. In this case study we describe the molecular characterization of a pediatric HGG and the use of an integrated approach based on genomic, in vitro and in vivo testing to identify actionable targets and treatment options. Molecular analysis based on WGS performed on initial and recurrent tumor biopsies revealed mutations in TP53, TSC1 and CIC genes, focal amplification of MYCN, and copy number gains in SMO and c-MET. Transcriptomic analysis identified increased expression of MYCN, and genes involved in sonic hedgehog signaling proteins (SHH, SMO, GLI1, GLI2) and receptor tyrosine kinase pathways (PLK, AURKA, c-MET). HTS revealed no cytotoxic efficacy of SHH pathway inhibitors while sensitivity was observed to the mTOR inhibitor temsirolimus, the ALK inhibitor ceritinib, and the PLK1 inhibitor BI2536. Based on the integrated approach, temsirolimus, ceritinib, BI2536 and standard therapy temozolomide were selected for further in vivo evaluation. Using the PDX animal model (median survival 28 days) we showed significant in vivo activity for mTOR inhibition by temsirolimus and BI2536 (median survival 109 and 115.5 days respectively) while ceritinib and temozolomide had only a moderate effect (43 and 75.5 days median survival respectively). This case study demonstrates that an integrated approach based on genomic, in vitro and in vivo drug efficacy testing in a PDX model may be useful to guide the management of high risk pediatric brain tumor in a clinically meaningful timeframe.