ZFTA-RELA+ ependymomas are malignant brain tumours defined by fusions formed between the putative chromatin remodeller ZFTA and the NF-κB mediator RELA1. Here we show that ZFTA-RELA+ cells produce itaconate, a key macrophage-associated immunomodulatory metabolite2. Itaconate is generated by cis-aconitate decarboxylase 1 (ACOD1; also known as IRG1). However, the production of itaconate by tumour cells and its tumour-intrinsic role are not well established. ACOD1 is upregulated in a ZFTA-RELA-dependent manner. Functionally, itaconate enables a feed-forward system that is crucial for the maintenance of pathogenic ZFTA-RELA levels. Itaconate epigenetically activates ZFTA-RELA transcription by enriching for activating H3K4me3 via inhibition of the H3K4 demethylase KDM5. ZFTA-RELA+ tumours enhance glutamine metabolism to supply carbons for itaconate synthesis. Antagonism of ACOD1 or glutamine metabolism reduces pathogenic ZFTA-RELA levels and is potently therapeutic in multiple in vivo models. Mechanistically, ZFTA-RELA epigenetically suppresses PTEN expression to upregulate PI3K-mTOR signalling, a known driver of glutaminolysis. Finally, suppression of ACOD1 or a combination of glutamine antagonism with PI3K-mTOR inhibition abrogates spinal metastasis. Our data demonstrate that ZFTA-RELA+ ependymomas subvert a macrophage-like itaconate metabolic pathway to maintain expression of the ZFTA-RELA driver, which implicates itaconate as a candidate oncometabolite. Taken together, our results position itaconate upregulation as a previously unappreciated driver of ZFTA-RELA+ ependymomas. Our work has implications for future drug development to reduce pathogenic ZFTA-RELA expression for this brain tumour, and will advance our understanding of oncometabolites as a new class of therapeutic dependencies in cancers.

Chordomas are rare cancers that arise along the axial skeleton. Alterations in metabolism are a hallmark of cancer, and we sought to identify metabolic vulnerabilities in chordoma. We discovered that the tricarboxylic acid (TCA)-related enzyme isocitrate dehydrogenase-1 (IDH1) was expressed highly in bulk and single-cell patient-derived chordomas and was associated with worse survival outcomes. IDH1 catalyzes the conversion of isocitrate and nicotinamide adenine dinucleotide phosphate (NADP+) to alpha-ketoglutarate (⍺-KG) and NADPH. This critical reaction influences TCA cycle metabolism, regulates epigenetic pathways, and affects redox balance. Both IDH1 knockdown and treatment with an inhibitor targeting IDH1 were toxic to chordoma cells. An integrated analysis of the transcriptomic, chromatin, and metabolomic responses on IDH1 inhibition converged on deregulated glutathione metabolism. IDH1 inhibition was associated with increased expression and enrichment of activating H3K27ac at NRF2 (nuclear factor erythroid 2-related factor 2) signature genes including those in the glutathione biosynthetic pathway. This was accompanied by reduction of both NADPH/NADP+ and reduced/oxidized glutathione (GSH/GSSG) ratios. Importantly, IDH1 inhibitor-driven toxicity was rescued via media supplementation with the antioxidant N-acetylcysteine, suggesting that IDH1 inhibition in chordomas creates a redox-dependent metabolic vulnerability. Finally, IDH1 inhibitor treatment reduced tumor growth in two independent chordoma mouse xenograft models. Our findings suggest a potential therapeutic avenue for further exploration in chordoma.

Abstract We sought to delineate, and target integrated metabolic and epigenetic pathways in cMYC-driven Group-3 medulloblastoma (MB). In a comprehensive screen, we identified upregulation of wild type isocitrate dehydrogenase 1 (IDH1) in Group-3 MB. Surprisingly, genetic and pharmacologic targeting of IDH1 reduced cMYC expression levels and was therapeutic in three independent (patient-derived D283, p = 0.0004; D341, p = 0.0008 and syngeneic murine Group-3 MB p = 0.0005) Group-3 MB animal models in vivo, but not in non-group 3 ONS76 animals (p = 0.1771). Mechanistically, IDH1 inhibition epigenetically suppressed cMYC expression by increasing repressive methylation marks at the cMYC locus. Additionally, we noted that IDH1 inhibition triggered a novel copper-dependent form of cell death termed cuproptosis. This mechanism was via cMYC-dependent downregulation of dihydrolipoyl transacetylase (DLAT), the E2-subunit of pyruvate dehydrogenase complex (PDC). Forced in vivo increase in tumor cellular copper levels by treating with Elesclomol, a blood-brain-barrier penetrant copper ionophore reduced tumor burden and increased overall survival in three independent (patient-derived D283, p = 0.0009; D341, p = 0.0188 and syngeneic murine Group-3 MB p = 0.0002) Group-3 MB animal models in vivo, but not in non-group 3 ONS76 animals (p = 0.1307). Our work establishes an integrated metabolic/epigenetic pathway driven by wild type IDH1 which serves as a gatekeeper to regulate cMYC expression and downstream copper metabolism in Group-3 MB. This novel pathway can be therapeutically leveraged using the blood-brain-barrier penetrant copper ionophore elesclomol that is currently in clinical trials for adult cancers.

Mutagenic processes and clonal selection contribute to the development of therapy-associated secondary neoplasms, a known complication of cancer treatment. The association between tamoxifen therapy and secondary uterine cancers is uncommon but well established; however, the genetic mechanisms underlying tamoxifen-driven tumorigenesis remain unclear. We find that oncogenic PIK3CA mutations, common in spontaneously arising estrogen-associated de novo uterine cancer, are significantly less frequent in tamoxifen-associated tumors. In vivo, tamoxifen-induced estrogen receptor stimulation activates phosphoinositide 3-kinase (PI3K) signaling in normal mouse uterine tissue, potentially eliminating the selective benefit of PI3K-activating mutations in tamoxifen-associated uterine cancer. Together, we present a unique pathway of therapy-associated carcinogenesis in which tamoxifen-induced activation of the PI3K pathway acts as a non-genetic driver event, contributing to the multistep model of uterine carcinogenesis. While this PI3K mechanism is specific to tamoxifen-associated uterine cancer, the concept of treatment-induced signaling events may have broader applicability to other routes of tumorigenesis.

GSEA of genes associated with positive or negative correlation with radiographic response to ONC201 treatment.

The interplay between metabolomics and epigenetics is a key glioma driver. Both tumor-intrinsic and microenvironmental metabolic cues can shape chromatin. Epigenetic methylation and demethylation are metabolically regulated by S -adenosyl methionine (SAM) (via methionine metabolism) and the TCA-cycle–related metabolite α-ketoglutarate (α-KG), respectively. Additionally, glycolysis and the TCA cycle modulate histone acetylation and lactylation. Gliomas in both adults and children hijack these pathways. Adult isocitrate dehydrogenase (IDH)-wild-type tumors enhance glycolysis via epidermal growth factor receptor to alter chromatin. IDH-mutant gliomas generate D-2-hydroxyglutarate (D-2HG), which inhibits α-KG demethylases to create epigenetic hypermethylation. Pediatric gliomas, including gliomas with lysine-to-methionine mutations at residue 27 of histone H3 and posterior fossa group A ependymomas, can also rewire metabolism to regulate chromatin. These pathways can be targeted for therapeutic development. Inhibiting IDH mutations with vorasidenib lowers D-2HG and is beneficial to patients. Other drugs like ONC201 and metformin can metabolically suppress oncogenic chromatin states in pediatric gliomas. This dynamic cross talk between metabolism and epigenetics not only underpins tumor biology but also presents opportunities for innovative therapeutic strategies.

GSEA analysis of genes with significantly lower chromatin accessibility at promoters and enhancers and reduced gene expression in DIPG007 cells treated with ONC201 versus vehicle.

VST-transformed gene expression values for all samples and protein-coding genes.

MYC-driven group-3 medulloblastomas (MBs) are malignant pediatric brain cancers without cures. To define actionable metabolic dependencies, we identify upregulation of dihydrolipoyl transacetylase (DLAT), the E2-subunit of pyruvate dehydrogenase complex (PDC) in a subset of group-3 MB with poor prognosis. DLAT is induced by c-MYC and targeting DLAT lowers TCA cycle metabolism and glutathione synthesis. We also note upregulation of isocitrate dehydrogenase 1 (IDH1) gene expression in group-3 MB patient tumors and suppression of IDH1 epigenetically reduces c-MYC and downstream DLAT levels in multiple c-MYC amplified cancers. DLAT is a central regulator of cuproptosis (copper-dependent cell death) induced by the copper ionophore elesclomol. DLAT expression in group-3 MB cells correlates with increased sensitivity to cuproptosis. Elesclomol is brain-penetrant and suppresses tumor growth in vivo in multiple group-3 MB animal models. Our data uncover an IDH1/c-MYC dependent vulnerability that regulates DLAT levels and can be targeted to kill group-3 MB by cuproptosis.

MYC-driven Group-3 medulloblastomas (MB) are deadly and malignant pediatric brain cancers and we sought to define actionable metabolic dependencies in these tumors. To identify uniquely upregulated genes in Group-3 MB, we performed transcriptomic analysis on two previously published medulloblastoma RNA-seq datasets. To elucidate the relationship between c-MYC/IDH1/DLAT and assess impact on tumor metabolism, we performed metabolic and transcriptional profiling of Group-3 MB cell lines that were either untreated or were subjected to shRNA-mediated knockdown of DLAT or treatment with IDH1 inhibitor. We also treated Group-3 MB cell lines containing varying levels of DLAT expression with copper ionophore elesclomol and assessed its ability to induce toxicity. Finally, we established in vivo models of Group-3 MB via orthotopic implantation to assess the effect of DLAT knockdown, IDH1 inhibition, and cuproptosis induction on tumor growth and survival outcomes. We identified upregulation of dihydrolipoyl transacetylase (DLAT), the E2-subunit of pyruvate dehydrogenase complex (PDC) in a subset of Group-3 MB. DLAT was induced by c-MYC and targeting DLAT lowered TCA-cycle metabolism and glutathione synthesis in Group-3 MB cells. We also noted upregulation of isocitrate dehydrogenase 1 (IDH1) in Group-3 MB. Remarkably, genetic and pharmacologic suppression of IDH1 epigenetically reduced c-MYC and downstream DLAT levels. DLAT is a central regulator of cuproptosis, a copper-dependent cell death mechanism induced by the copper ionophore elesclomol. DLAT expression in Group-3 MB cells correlated with increased sensitivity to cuproptosis. Elesclomol was CNS-penetrant and suppressed tumor growth in vivo in Group-3 MB animal models. Our data uncover an IDH1/c-MYC dependent vulnerability that regulates DLAT levels and can be targeted to kill Group-3 MB by cuproptosis.

Protocol for NCT03416530, ONC201-014: ONC201 in Newly Diagnosed Diffuse Intrinsic Pontine Glioma and Recurrent/Refractory Pediatric H3K27M Gliomas.

Upregulated and downregulated metabolites in DIPG007 cells treated with ONC201 versus vehicle.

Upregulated and downregulated genes in DIPG007 cells treated with ONC201 versus vehicle.

Radiographic response versus gene expression Spearman's correlation coefficient for all protein-coding genes.

GSEA analysis of genes with significantly increased H3K27me3 in ONC201-treated versus untreated patients.

Protocol for NCT03134131, ONC201-018: Expanded Access to ONC201 for Patients with H3K27M-mutant and/or Midline High Grade Gliomas.

Globally decreased histone 3, lysine 27 tri-methylation (H3K27me3) is a hallmark of H3K27-altered diffuse midline gliomas (DMGs) and group-A posterior fossa ependymomas (PFAs). H3K27-altered DMGs are largely characterized by lysine-to-methionine mutations in histone 3 at position 27 (H3K27M). Most PFAs overexpress EZH inhibitory protein (EZHIP), which possesses a region of similarity to the mutant H3K27M. Both H3K27M and EZHIP inhibit the function of the polycomb repressive complex 2 (PRC2) responsible for H3K27me3 deposition. These tumors often arise in neighboring regions of the brainstem and posterior fossa. In rare cases PFAs harbor H3K27M mutations, and DMGs overexpress EZHIP. These findings together raise the possibility that certain cell populations in the developing hindbrain/posterior fossa are especially sensitive to modulation of H3K27me3 states. We identified shared molecular features by comparing genomic, bulk transcriptomic, chromatin-based profiles, and single-cell RNA-sequencing (scRNA-seq) data from the two tumor classes. Our approach demonstrated that 1q gain, a key biomarker in PFAs, is prognostic in H3.1K27M, but not H3.3K27M gliomas. Conversely, Activin A Receptor Type 1 (ACVR1), which is associated with mutations in H3.1K27M gliomas, is overexpressed in a subset of PFAs with poor outcome. Despite diffuse H3K27me3 reduction, previous work shows that both tumors maintain genomic H3K27me3 deposition at select sites. We demonstrate heterogeneity in shared patterns of residual H3K27me3 for both tumors that largely segregated with inferred anatomic tumor origins and progenitor populations of tumor cells. In contrast, analysis of genes linked to H3K27 acetylation (H3K27ac)-marked enhancers showed higher expression in astrocytic-like tumor cells. Finally, common H3K27me3-marked genes mapped closely to expression patterns in the human developing hindbrain. Overall, our data demonstrate developmentally relevant molecular similarities between PFAs and H3K27M DMGs and support the overall hypothesis that deregulated mechanisms of hindbrain development are central to the biology of both tumors.

Results of pathway impact analysis after performing integrated RNA-seq and metabolomics analysis using MetaboAnalyst.