ONC201: a new treatment option being tested clinically for recurrent glioblastoma

Chaetocin-mediated SUV39H1 inhibition targets stemness and oncogenic networks of diffuse midline gliomas and synergizes with ONC201

BACKGROUND

Diffuse intrinsic pontine gliomas (DIPG/DMG) are devastating pediatric brain tumors with extraordinarily limited treatment options and uniformly fatal prognosis. Histone H3K27M mutation is a common recurrent alteration in DIPG and disrupts epigenetic regulation. We hypothesize that genome-wide H3K27M-induced epigenetic dysregulation makes tumors vulnerable to epigenetic targeting.

METHODS

We performed a screen of compounds targeting epigenetic enzymes to identify potential inhibitors for the growth of patient-derived DIPG cells. We further carried out transcriptomic and genomic landscape profiling including RNA-seq and CUT&RUN-seq as well as shRNA-mediated knockdown to assess the effects of chaetocin and SUV39H1, a target of chaetocin, on DIPG growth.

RESULTS

High-throughput small-molecule screening identified an epigenetic compound chaetocin as a potent blocker of DIPG cell growth. Chaetocin treatment selectively decreased proliferation and increased apoptosis of DIPG cells and significantly extended survival in DIPG xenograft models, while restoring H3K27me3 levels. Moreover, the loss of H3K9 methyltransferase SUV39H1 inhibited DIPG cell growth. Transcriptomic and epigenomic profiling indicated that SUV39H1 loss or inhibition led to the downregulation of stemness and oncogenic networks including growth factor receptor signaling and stemness-related programs; however, D2 dopamine receptor (DRD2) signaling adaptively underwent compensatory upregulation conferring resistance. Consistently, a combination of chaetocin treatment with a DRD2 antagonist ONC201 synergistically increased the antitumor efficacy.

CONCLUSIONS

Our studies reveal a therapeutic vulnerability of DIPG cells through targeting the SUV39H1-H3K9me3 pathway and compensatory signaling loops for treating this devastating disease. Combining SUV39H1-targeting chaetocin with other agents such as ONC201 may offer a new strategy for effective DIPG treatment.

Gemcitabine elaidate and ONC201 combination therapy for inhibiting pancreatic cancer in a KRAS mutated syngeneic mouse model

Approximately 90% of pancreatic cancer (PC) contain KRAS mutations. Mutated KRAS activates the downstream oncogenic PI3K/AKT and MEK signaling pathways and induces drug resistance. However, targeting both pathways with different drugs can also lead to excessive toxicity. ONC201 is a dual PI3K/AKT and MEK pathway inhibitor with an excellent safety profile that targets death receptor 5 (DR5) to induce apoptosis. Gemcitabine (GEM) is a first-line chemotherapy in PC, but it is metabolically unstable and can be stabilized by a prodrug approach. In this study, phospho-Akt, phospho-mTOR, and phospho-ERK protein expressions were evaluated in patient PDAC-tissues (n = 10). We used lipid-gemcitabine (L_GEM) conjugate, which is more stable and enters the cells by passive diffusion. Further, we evaluated the efficacy of L_GEM and ONC201 in PC cells and "KrasLSL-G12D; p53LoxP; Pdx1-CreER (KPC) triple mutant xenograft tumor-bearing mice. PDAC patient tissues showed significantly higher levels of p-AKT (Ser473), p-ERK (T202/T204), and p-mTOR compared to surrounding non-cancerous tissues. ONC201 in combination with L_GEM, showed a superior inhibitory effect on the growth of MIA PaCa-2 cells. In our in-vivo study, we found that ONC201 and L_GEM combination prevented neoplastic proliferation via AKT/ERK blockade to overcome chemoresistance and increased T-cell tumor surveillance. Simultaneous inhibition of the PI3K/AKT and MEK pathways with ONC201 is an attractive approach to potentiate the effect of GEM. Our findings provide insight into rational-directed precision chemo and immunotherapy therapy in PDAC.

Harmaline to Human Mitochondrial Caseinolytic Serine Protease Activation for Pediatric Diffuse Intrinsic Pontine Glioma Treatment

Diffuse intrinsic pontine glioma (DIPG), affecting children aged 4-7 years, is a rare, aggressive tumor that originates in the pons and then spreads to nearby tissue. DIPG is the leading cause of death for pediatric brain tumors due to its infiltrative nature and inoperability. Radiotherapy has only a palliative effect on stabilizing symptoms. In silico and preclinical studies identified ONC201 as a cytotoxic agent against some human cancer cell lines, including DIPG ones. A single-crystal X-ray analysis of the complex of the human mitochondrial caseinolytic serine protease type C (hClpP) and ONC201 (PDB ID: 6DL7) allowed hClpP to be identified as its main target. The hyperactivation of hClpP causes damage to mitochondrial oxidative phosphorylation and cell death. In some DIPG patients receiving ONC201, an acquired resistance was observed. In this context, a wide program was initiated to discover original scaffolds for new hClpP activators to treat ONC201-non-responding patients. Harmaline, a small molecule belonging to the chemical class of β-carboline, was identified through Fingerprints for Ligands and Proteins (FLAP), a structure-based virtual screening approach. Molecular dynamics simulations and a deep in vitro investigation showed interesting information on the interaction and activation of hClpP by harmaline.

ONC201/TIC10 plus TLY012 anti-cancer effects via apoptosis inhibitor downregulation, stimulation of integrated stress response and death receptor DR5 in gastric adenocarcinoma

Gastric adenocarcinoma typically presents with advanced stage when inoperable. Chemotherapy options include non-targeted and toxic agents, leading to poor 5-year patient survival outcomes. Small molecule ONC201/TIC10 (TRAIL-Inducing Compound #10) induces cancer cell death via ClpP-dependent activation of the integrated stress response (ISR) and up-regulation of the TRAIL pathway. We previously found in breast cancer, pancreatic cancer and endometrial cancer that ONC201 primes tumor cells for TRAIL-mediated cell death through ISR-dependent upregulation of ATF4, CHOP and TRAIL death receptor DR5. We investigated the ability of ONC201 to induce apoptosis in gastric adenocarcinoma cells in combination with recombinant human TRAIL (rhTRAIL) or PEGylated trimeric TRAIL (TLY012). AGS (caspase 8-, KRAS-, PIK3CA-mutant, HER2-amplified), SNU-1 (KRAS-, MLH1-mutant, microsatellite unstable), SNU-5 (p53-mutant) and SNU-16 (p53-mutant) gastric adenocarcinoma cells were treated with ONC201 and TRAIL both in cell culture and in vivo. Gastric cancer cells showed synergy following dual therapy with ONC201 and rhTRAIL/TLY012 (combination indices < 0.6 at doses that were non-toxic towards normal fibroblasts). Synergy was observed with increased cells in the sub-G1 phase of the cell cycle with dual ONC201 plus TRAIL therapy. Increased PARP, caspase 8 and caspase 3 cleavage after ONC201 plus TRAIL further documented apoptosis. Increased cell surface expression of DR5 with ONC201 therapy was observed by flow cytometry, and immunoblotting revealed ONC201 upregulation of the ISR, ATF4, and CHOP. We observed downregulation of anti-apoptotic cIAP-1 and XIAP in all cells except AGS, and cFLIP in all cells except SNU-16. We tested the regimen in an organoid model of human gastric cancer, and in murine sub-cutaneous xenografts using AGS and SNU-1 cells. Our results suggest that ONC201 in combination with TRAIL may be an effective and non-toxic option for the treatment of gastric adenocarcinoma by inducing apoptosis via activation of the ISR, increased cell surface expression of DR5 and down-regulation of inhibitors of apoptosis. Our results demonstrate in vivo anti-tumor effects of ONC201 plus TLY012 against gastric cancer that could be further investigated in clinical trials.

Molecular Mechanisms Involved in the Chemical Instability of ONC201 and Methods to Counter Its Degradation in Solution

Glioblastoma is one of the most common and aggressive forms of brain tumor, a rare disease for which there is a great need for innovative therapies. ONC201, a new drug substance, has been used in a compassionate treatment program where the choice of dosage form and regimen have yet to be justified. The prior knowledge needed to anticipate ONC201 stability problems has recently been partially addressed, by (i) showing that ONC201 is sensitive to light and oxidation and (ii) identifying the molecular structures of the main degradation products formed. The aim of the work presented here was to improve our understanding of the degradation pathways of ONC201 using data from ab initio calculations and experimental work to supplement the structural information we already published. The C-H bonds located αto the amine of the tetrahydropyridine group and those located alpha to the imine function of the dihydroimidazole group exhibit the lowest bond dissociation energies (BDEs) within the ONC201 molecule. Moreover, these values drop well below 90 kcal.mol-1 when ONC201 is in an excited state (S1; T1). The structures of the photoproducts we had previously identified are consistent with these data, showing that they would have resulted from radical processes following the abstraction of alpha hydrogens. Concerning ONC201's sensitivity to oxidation, the structures of the oxidation products matched the critical points revealed through mapped electrostatic potential (MEP) and average local ionization energy (ALIE). The data obtained from ab initio calculations and experimental work showed that the reactivity of ONC201 to light and oxidation conditions is highly dependent on pH. While an acidic environment (pH < 6) contributes to making ONC201 quantitatively more stable in solution in the face of oxidation and photo-oxidation, it nevertheless seems that certain chemical groups in the molecule are more exposed to nucleophilic attacks, which explains the variation observed in the profile of degradation products formed in the presence of certain antioxidants tested. This information is crucial to better understand the stability results in the presence of antioxidant agents and to determine the right conditions for them to act.

Pediatric Central Nervous System Tumor Overview and Emerging Treatment Considerations

Pediatric central nervous system (CNS) tumors are the most common solid tumor in children, with the majority being glial in origin. These tumors are classified by the World Health Organization (WHO) as either being low grade (WHO grade 1 and 2) or high grade (WHO grade 3 and 4). Our knowledge of the molecular landscape of pediatric brain tumors has advanced over the last decade, which has led to newer categorizations along with an expansion of therapeutic targets and options. In this review, we will give an overview of common CNS tumors seen in children along with a focus on treatment options and future considerations.

Wnt Signaling in Brain Tumors: A Challenging Therapeutic Target

The involvement of Wnt signaling in normal tissue homeostasis and disease has been widely demonstrated over the last 20 years. In particular, dysregulation of Wnt pathway components has been suggested as a relevant hallmark of several neoplastic malignancies, playing a role in cancer onset, progression, and response to treatments. In this review, we summarize the current knowledge on the instructions provided by Wnt signaling during organogenesis and, particularly, brain development. Moreover, we recapitulate the most relevant mechanisms through which aberrant Wnt pathway activation may impact on brain tumorigenesis and brain tumor aggressiveness, with a particular focus on the mutual interdependency existing between Wnt signaling components and the brain tumor microenvironment. Finally, the latest anti-cancer therapeutic approaches employing the specific targeting of Wnt signaling are extensively reviewed and discussed. In conclusion, here we provide evidence that Wnt signaling, due to its pleiotropic involvement in several brain tumor features, may represent a relevant target in this context, although additional efforts will be needed to: (i) demonstrate the real clinical impact of Wnt inhibition in these tumors; (ii) overcome some still unsolved concerns about the potential systemic effects of such approaches; (iii) achieve efficient brain penetration.

Multi-omics analyses reveal ClpP activators disrupt essential mitochondrial pathways in triple-negative breast cancer

ClpP activators ONC201 and related small molecules (TR compounds, Madera Therapeutics), have demonstrated significant anti-cancer potential in vitro and in vivo studies, including clinical trials for refractory solid tumors. Though progress has been made in identifying specific phenotypic outcomes following ClpP activation, the exact mechanism by which ClpP activation leads to broad anti-cancer activity has yet to be fully elucidated. In this study, we utilized a multi-omics approach to identify the ClpP-dependent proteomic, transcriptomic, and metabolomic changes resulting from ONC201 or the TR compound TR-57 in triple-negative breast cancer cells. Applying mass spectrometry-based methods of proteomics and metabolomics, we identified ∼8,000 proteins and 588 metabolites, respectively. From proteomics data, 113 (ONC201) and 191 (TR-57) proteins significantly increased and 572 (ONC201) and 686 (TR-57) proteins significantly decreased in this study. Gene ontological (GO) analysis revealed strong similarities between proteins up- or downregulated by ONC201 or TR-57 treatment. Notably, this included the downregulation of many mitochondrial processes and proteins, including mitochondrial translation and mitochondrial matrix proteins. We performed a large-scale transcriptomic analysis of WT SUM159 cells, identifying ∼7,700 transcripts (746 and 1,100 significantly increasing, 795 and 1,013 significantly decreasing in ONC201 and TR-57 treated cells, respectively). Less than 21% of these genes were affected by these compounds in ClpP null cells. GO analysis of these data demonstrated additional similarity of response to ONC201 and TR-57, including a decrease in transcripts related to the mitochondrial inner membrane and matrix, cell cycle, and nucleus, and increases in other nuclear transcripts and transcripts related to metal-ion binding. Comparison of response between both compounds demonstrated a highly similar response in all -omics datasets. Analysis of metabolites also revealed significant similarities between ONC201 and TR-57 with increases in α-ketoglutarate and 2-hydroxyglutaric acid and decreased ureidosuccinic acid, L-ascorbic acid, L-serine, and cytidine observed following ClpP activation in TNBC cells. Further analysis identified multiple pathways that were specifically impacted by ClpP activation, including ATF4 activation, heme biosynthesis, and the citrulline/urea cycle. In summary the results of our studies demonstrate that ONC201 and TR-57 induce highly similar and broad effects against multiple mitochondrial processes required for cell proliferation.

Pediatric diffuse midline glioma: Understanding the mechanisms and assessing the next generation of personalized therapeutics

Diffuse midline glioma (DMG) is a pediatric cancer that originates in the midline structures of the brain. Prognosis of DMG patients remains poor due to the infiltrative nature of these tumors and the protection they receive from systemically delivered therapeutics via an intact blood-brain barrier (BBB), making treatment difficult. While the cell of origin remains disputed, it is believed to reside in the ventral pons. Recent research has pointed toward epigenetic dysregulation inducing an OPC-like transcriptomic signature in DMG cells. This epigenetic dysregulation is typically caused by a mutation (K27M) in one of two histone genes-H3F3A or HIST1H3B -and can lead to a differentiation block that increases these cells oncogenic potential. Standard treatment with radiation is not sufficient at overcoming the aggressivity of this cancer and only confers a survival benefit of a few months, and thus, discovery of new therapeutics is of utmost importance. In this review, we discuss the cell of origin of DMGs, as well as the underlying molecular mechanisms that contribute to their aggressivity and resistance to treatment. Additionally, we outline the current standard of care for DMG patients and the potential future therapeutics for this cancer that are currently being tested in preclinical and clinical trials.

Current approaches in enhancing TRAIL therapies in glioblastoma

Glioblastoma (GBM) is the most prevalent, aggressive, primary brain cancer in adults and continues to pose major medical challenges due in part to its high rate of recurrence. Extensive research is underway to discover new therapies that target GBM cells and prevent the inevitable recurrence in patients. The pro-apoptotic protein tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has attracted attention as an ideal anticancer agent due to its ability to selectively kill cancer cells with minimal toxicity in normal cells. Although initial clinical evaluations of TRAIL therapies in several cancers were promising, later stages of clinical trial results indicated that TRAIL and TRAIL-based therapies failed to demonstrate robust efficacies due to poor pharmacokinetics, resulting in insufficient concentrations of TRAIL at the therapeutic site. However, recent studies have developed novel ways to prolong TRAIL bioavailability at the tumor site and efficiently deliver TRAIL and TRAIL-based therapies using cellular and nanoparticle vehicles as drug loading cargos. Additionally, novel techniques have been developed to address monotherapy resistance, including modulating biomarkers associated with TRAIL resistance in GBM cells. This review highlights the promising work to overcome the challenges of TRAIL-based therapies with the aim to facilitate improved TRAIL efficacy against GBM.

Diagnostic and therapeutic potential of protease inhibition

Proteases are enzymes that hydrolyze peptide bonds in proteins and peptides; thus, they control virtually all biological processes. Our understanding of protease function has advanced considerably from nonselective digestive enzymes to highly specialized molecular scissors that orchestrate complex signaling networks through a limited proteolysis. The catalytic activity of proteases is tightly regulated at several levels, ranging from gene expression through trafficking and maturation to posttranslational modifications. However, when this delicate balance is disturbed, many diseases develop, including cancer, inflammatory disorders, diabetes, and neurodegenerative diseases. This new understanding of the role of proteases in pathologic physiology indicates that these enzymes represent excellent molecular targets for the development of therapeutic inhibitors, as well as for the design of chemical probes to visualize their redundant activity. Recently, numerous platform technologies have been developed to identify and optimize protease substrates and inhibitors, which were further used as lead structures for the development of chemical probes and therapeutic drugs. Due to this considerable success, the clinical potential of proteases in therapeutics and diagnostics is rapidly growing and is still not completely explored. Therefore, small molecules that can selectively target aberrant protease activity are emerging in diseases cells. In this review, we describe modern trends in the design of protease drugs as well as small molecule activity-based probes to visualize selected proteases in clinical settings.

Anticancer efficacy of endo- and exogenous potent ligands acting at dopaminergic receptor-expressing cancer cells

Cancer is one of the most common and dreaded diseases affecting the vastness of society. Unfortunately, still some people die especially when cancer is not diagnosed and thus caught early enough. On the other hand, using available chemo- or radiotherapy may result in serious side effects. Therefore, cancer-specific medications seem to be the most desired and safe therapy. Knowing that some cancers are characterized by overexpression of specific receptors on the cell surface, target-mediated drugs could serve as a unique and effective form of therapy. In line with this, recently dopaminergic receptors were presented important in cancer therapy as several dopaminergic ligands revealed their efficacy in tumor growth reduction as well as in apoptosis mediation. Unfortunately, the indication of whether DA receptor agonists or antagonists are the best choices in cancer treatment is quite difficult, since both of them may exert either pro- or anticancer effects. In this review, we analyze the therapeutic efficacy of compounds, both of exogenous and endogenous origin, targeting dopaminergic receptor-expressing cancers.

Glioblastoma: Current Status, Emerging Targets, and Recent Advances

Glioblastoma (GBM) is a highly malignant brain tumor characterized by a heterogeneous population of genetically unstable and highly infiltrative cells that are resistant to chemotherapy. Although substantial efforts have been invested in the field of anti-GBM drug discovery in the past decade, success has primarily been confined to the preclinical level, and clinical studies have often been hampered due to efficacy-, selectivity-, or physicochemical property-related issues. Thus, expansion of the list of molecular targets coupled with a pragmatic design of new small-molecule inhibitors with central nervous system (CNS)-penetrating ability is required to steer the wheels of anti-GBM drug discovery endeavors. This Perspective presents various aspects of drug discovery (challenges in GBM drug discovery and delivery, therapeutic targets, and agents under clinical investigation). The comprehensively covered sections include the recent medicinal chemistry campaigns embarked upon to validate the potential of numerous enzymes/proteins/receptors as therapeutic targets in GBM.

Diffuse Intrinsic Pontine Glioma (DIPG): Breakthrough and Clinical Perspective

Diffuse intrinsic pontine glioma (DIPG) mainly affects children with a median age of 6-7 years old. It accounts for 10% of all pediatric tumors. Unfortunately, DIPG has a poor prognosis, and the median survival is generally less than 16-24 months independently from the treatment received. Up to now, children with DIPG are treated with focal radiotherapy alone or in combination with antitumor agents. In the last decade, ONC201 known as dopamine receptor antagonist was uncovered, by a high throughput screening of public libraries of compounds, to be endowed with cytotoxic activity against several cancer cell lines. Efforts were made to identify the real ONC201 target, responsible for its antiproliferative effect. The hypothesized targets were the Tumor necrosis factor-Related Apoptosis-Inducing Ligand stimulation (TRAIL), two oncogenic kinases (ERK/AKT system) that target the same tumor-suppressor gene (FOXO3a), dopamine receptors (DRD2 and DRD3 subtypes) and finally the mitochondrial Caseynolitic Protease P (ClpP). ONC201 structure-activity relationship is extensively discussed in this review, together with other two classes of compounds, namely ADEPs and D9, already known for their antibiotic activity but noteworthy to be discussed and studied as potential "leads" for the development of new drugs to be used in the treatment of DIPG. In this review, a detailed and critical description of ONC201, ADEPs, and D9 pro-apoptotic activity is made, with particular attention to the specific interactions established with its targets that also are intimately described. Pubmed published patents and clinical trial reports of the last ten years were used as the bibliographic source.

Microarray analysis reveals ONC201 mediated differential mechanisms of CHOP gene regulation in metastatic and nonmetastatic colorectal cancer cells

The imipramine ONC201 has antiproliferative effects in several cancer cell types and activates integrated stress response pathway associated with the induction of Damage Inducible Transcript 3 (DDIT3, also known as C/EBP homologous protein or CHOP). We investigated the signaling pathways through which ONC201/CHOP crosstalk is regulated in ONC201-treated nonmetastatic and metastatic cancer cell lines (Dukes' type B colorectal adenocarcinoma nonmetastatic SW480 and metastatic LS-174T cells, respectively). Cell proliferation and apoptosis were evaluated by MTT assays and flow cytometry, gene expression was assessed by Affymetrix microarray, signaling pathway perturbations were assessed in silico, and key regulatory proteins were validated by Western blotting. Unlike LS-174T cells, SW480 cells were resistant to ONC201 treatment; Gene Ontology analysis of differentially expressed genes showed that cellular responsiveness to ONC201 treatment also differed substantially. In both ONC201-treated cell lines, CHOP expression was upregulated; however, its upstream regulatory mechanisms were perturbed. Although, PERK, ATF6 and IRE1 ER-stress pathways upregulated CHOP in both cell types, the Bak/Bax pathway regulated CHOP only LS-174T cells. Additionally, CHOP RNA splicing profiles varied between cell lines; these were further modified by ONC201 treatment. In conclusion, we delineated the signaling mechanisms by which CHOP expression is regulated in ONC201-treated non-metastatic and metastatic colorectal cell lines. The observed differences could be related to cellular plasticity and metabolic reprogramming, nevertheless, detailed mechanistic studies are required for further validations.

ONC201 induces the unfolded protein response (UPR) in high- and low-grade ovarian carcinoma cell lines and leads to cell death regardless of platinum sensitivity

Objectives

Treatment of both platinum resistant high grade (HG) and low‐grade (LG) ovarian cancer (OVCA) poses significant challenges as neither respond well to conventional chemotherapy leading to morbidity and mortality. Identification of novel agents that can overcome chemoresistance is therefore critical. Previously, we have demonstrated that OVCA has basal upregulated unfolded protein response (UPR) and that targeting cellular processes leading to further and persistent upregulation of UPR leads to cell death. ONC201 is an orally bioavailable Dopamine Receptor D2 inhibitor demonstrating anticancer activity and was found to induce UPR. Given its unique properties, we hypothesized that ONC201 would overcome platinum resistance in OVCA.

Methods

Cisplatin sensitive and resistant HG OVCA and two primary LG OVCA cell lines were studied. Cell viability was determined using MTT assay. Cell migration was studied using wound healing assay. Apoptosis and mitochondrial membrane potential were investigated using flow cytometry. Analysis of pathway inhibition was performed by Western Blot. mRNA expression of UPR related genes were measured by qPCR. In vivo studies were completed utilizing axillary xenograft models. Co‐testing with conventional chemotherapy was performed to study synergy.

Results

ONC201 significantly inhibited cell viability and migration in a dose dependent manner with IC50’s from 1‐20 µM for both cisplatin sensitive and resistant HG and LG‐OVCA cell lines. ONC201 lead to upregulation of the pro‐apoptotic arm of the UPR, specifically ATF‐4/CHOP/ATF3 and increased the intrinsic apoptosispathway. The compensatory, pro‐survival PI3K/AKT/mTOR pathway was downregulated. In vivo, weekly dosing of single agent ONC201 decreased xenograft tumor size by ~50% compared to vehicle. ONC201 also demonstrated significant synergy with paclitaxel in a highly platinum resistant OVCA cell‐line (OV433).

Conclusions

Our findings demonstrate that ONC201 can effectively overcome chemoresistance in OVCA cells by blocking pro‐survival pathways and inducing the apoptotic arm of the UPR. This is a promising, orallybioavailable therapeutic agent to consider in clinical trials for patients with both HG and LG OVCA.

Overcoming TRAIL Resistance for Glioblastoma Treatment

The tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) shows a promising therapeutic potential in cancer treatment as it exclusively causes apoptosis in a broad spectrum of cancer cells through triggering the extrinsic apoptosis pathway via binding to cognate death receptors, with negligible toxicity in normal cells. However, most cancers, including glioblastoma multiforme (GBM), display TRAIL resistance, hindering its application in clinical practice. Recent studies have unraveled novel mechanisms in regulating TRAIL-induced apoptosis in GBM and sought effective combinatorial modalities to sensitize GBM to TRAIL treatment, establishing pre-clinical foundations and the reasonable expectation that the TRAIL/TRAIL death receptor axis could be harnessed to treat GBM. In this review, we will revisit the status quo of the mechanisms of TRAIL resistance and emerging strategies for sensitizing GBM to TRAIL-induced apoptosis and also discuss opportunities of TRAIL-based combinatorial therapies in future clinical use for GBM treatment.

A Systematic Review of Glioblastoma-Targeted Therapies in Phases II, III, IV Clinical Trials

Glioblastoma (GBM), the most frequent and aggressive glial tumor, is currently treated as first line by the Stupp protocol, which combines, after surgery, radiotherapy and chemotherapy. For recurrent GBM, in absence of standard treatment or available clinical trials, various protocols including cytotoxic drugs and/or bevacizumab are currently applied. Despite these heavy treatments, the mean overall survival of patients is under 18 months. Many clinical studies are underway. Based on clinicaltrials.org and conducted up to 1 April 2020, this review lists, not only main, but all targeted therapies in phases II-IV of 257 clinical trials on adults with newly diagnosed or recurrent GBMs for the last twenty years. It does not involve targeted immunotherapies and therapies targeting tumor cell metabolism, that are well documented in other reviews. Without surprise, the most frequently reported drugs are those targeting (i) EGFR (40 clinical trials), and more generally tyrosine kinase receptors (85 clinical trials) and (ii) VEGF/VEGFR (75 clinical trials of which 53 involving bevacizumab). But many other targets and drugs are of interest. They are all listed and thoroughly described, on an one-on-one basis, in four sections related to targeting (i) GBM stem cells and stem cell pathways, (ii) the growth autonomy and migration, (iii) the cell cycle and the escape to cell death, (iv) and angiogenesis.

Metabolic and inflammatory reprogramming of macrophages by ONC201 translates in a pro-inflammatory environment even in presence of glioblastoma cells

Tumor-associated macrophages facilitate tumor progression and resistance to therapy. Their capacity for metabolic and inflammatory reprogramming represents an attractive therapeutic target. ONC201/TIC10 is an anticancer molecule that antagonizes the dopamine receptor D2 and affects mitochondria integrity in tumor cells. We examined whether ONC201 induces a metabolic and pro-inflammatory switch in primary human monocyte-derived macrophages that reactivates their antitumor activities, thus enhancing the onco-toxicity of ONC201. Contrary to glioblastoma cells, macrophages exhibited a low ratio of dopamine receptors D2/D5 gene expression and were resistant to ONC201 cytotoxicity. Macrophages responded to ONC201 with a severe loss of mitochondria integrity, a switch to glycolytic ATP production, alterations in glutamate transport, and a shift towards a pro-inflammatory profile. Treatment of macrophages-glioblastoma cells co-cultures with ONC201 induced similar alterations in glutamatergic and inflammatory gene expression profiles of macrophages. It induced as well metabolic changes and a pro-inflammatory switch of the co-culture milieu. However, these changes did not translate into increased onco-toxicity. This study provides the first evidence that ONC201 affects macrophage immunometabolism and leads to a pro-inflammatory tumor environment. This speaks in favor of implementing ONC201 in combinatorial therapies and warrants further investigation of the mechanisms of action of ONC201 in macrophages and other immune cells.

Pediatric high-grade glioma: moving toward subtype-specific multimodal therapy

Pediatric high-grade gliomas (pHGG) comprise a deadly, heterogenous category of pediatric gliomas with a clear need for more effective treatment options. Advances in high-throughput molecular techniques have enhanced molecular understanding of these tumors, but outcomes are still poor, and treatments beyond resection and radiation have not yet been clearly established as standard of care. In this review, we first discuss the history of treatment approaches to pHGG to this point. We then review four distinct categories of pHGG, including histone 3-mutant, IDH-mutant, histone 3/IDH-wildtype, and radiation-induced pHGG. We discuss the molecular understanding of each subgroup and targeted treatment options in development. Finally, we look at the development and current status of two novel approaches to pHGG as a whole: localized convection-enhanced chemotherapy delivery and immunotherapy, including checkpoint inhibitors, vaccine therapy, and CAR-T cells. Through this review, we demonstrate the potential for rational, molecularly driven, subtype-specific therapy to be used with other novel approaches in combinations that could meaningfully improve the prognosis in pHGG.

Histone Mutations and Bone Cancers

Primary bone tumors are rare cancers that cause significant morbidity and mortality. The recent identification of recurrent mutations in histone genes H3F3A and H3F3B within specific bone cancers, namely, chondroblastomas and giant cell tumors of bone (GCTB), has provided insights into the cellular and molecular origins of these neoplasms and enhanced understanding of how histone variants control chromatin function. Somatic mutations in H3F3A and H3F3B produce oncohistones, H3.3G34W and H3.3K36M, in more than nine of ten GCTB and chondroblastomas, respectively. Incorporation of the mutant histones into nucleosomes inhibits histone methyltransferases NSD2 and SETD2 to alter the chromatin landscape and change gene expression patterns that control cell proliferation, survival, and differentiation, as well as DNA repair and chromosome stability. The discovery of these histone mutations has facilitated more accurate diagnoses of these diseases and stratification of malignant tumors from benign tumors so that appropriate care can be delivered. The broad-scale epigenomic and transcriptomic changes that arise from incorporation of mutant histones into chromatin provide opportunities to develop new and disease-specific therapies. In this chapter, we review how mutant histones inhibit SETD2 and NSD2 function in bone tumors and discuss how this information could lead to better treatments for these cancers.

Dopamine Receptors in Cancer: Are They Valid Therapeutic Targets?

The dopamine receptors (DRs) family includes 5 members with differences in signal transduction and ligand affinity. Abnormal DRs expression has been correlated multiple tumors with their clinical outcome. Thus, it has been proposed that DRs-targeting drugs-developed for other diseases as schizophrenia or Parkinson's disease-could be helpful in managing neoplastic diseases. In this review, we discuss the role of DRs and the effects of DRs-targeting in tumor progression and cancer cell biology using multiple high-prevalence neoplasms as examples. The evidence shows that DRs are valid therapeutic targets for certain receptor/disease combinations, but the data are inconclusive or contradictory for others. In either case, further studies are required to define the precise role of DRs in tumor progression and propose better therapeutic strategies for their targeting.

The role of MiRNA-21 in gliomas: Hope for a novel therapeutic intervention?

Gliomas are the most common primary brain tumors in adults. They are generally very resistant to treatment and are therefore associated with negative outcomes. MicroRNAs (miRNAs) are small, non-coding RNA molecules that affect many cellular processes by regulating gene expression and, post-transcriptionally, the translation of mRNAs. MiRNA-21 has been consistently shown to be upregulated in glioma and research has shown that it is involved in a wide variety of biological pathways, promoting tumor cell survival and invasiveness. Furthermore, it has been implicated in resistance to treatment, both against chemotherapy and radiotherapy. In this review, we gathered the existent data on miRNA-21 and gliomas, in terms of its expression levels, association with grade and prognosis, the pathways it involves and its targets in glioma, and finally how it leads to treatment resistance. Furthermore, we discuss how this knowledge could be applied in clinical practice in the years to come. To our knowledge, this is the first review to assess in extent and depth the role of miRNA-21 in gliomas.

Genomic profiling of newly diagnosed glioblastoma patients and its potential for clinical utility - a prospective, translational study

Glioblastoma (GBM) is an incurable brain tumor for which new treatment strategies are urgently needed. Next-generation sequencing of GBM has most often been performed retrospectively and on archival tissue from both diagnostic and relapse surgeries with limited knowledge of clinical information, including treatment given. We sought to investigate the genomic composition prospectively in treatment-naïve patients, searched for possible targetable aberrations, and investigated for prognostic and/or predictive factors. A total of 108 newly diagnosed GBM patients were included. Clinical information, progression-free survival, and overall survival (OS) were noted. Tissues were analyzed by whole-exome sequencing, single nucleotide polymorphism (SNP) and transcriptome arrays, and RNA sequencing; assessed for mutations, fusions, tumor mutational burden (TMB), and chromosomal instability (CI); and classified into GBM subgroups. Each genomic report was discussed at a multidisciplinary tumor board meeting to evaluate for matching trials. From 111 consecutive patients, 97.3% accepted inclusion in this study. Eighty-six (77%) were treated with radiation therapy/temozolomide (TMZ) and adjuvant TMZ. One NTRK2 and three FGFR3-TACC3 fusions were identified. Copy number alterations in GRB2 and SMYD4 were significantly correlated with worse median OS together with known clinical variables like age, performance status, steroid dose, and O6-methyl-guanine-DNA-methyl-transferase status. Patients with CI-median or TMB-high had significantly worse median OS compared to CI-low/high or TMB-low/median. In conclusion, performing genomic profiling at diagnosis enables evaluation of genomic-driven therapy at the first progression. Furthermore, TMB-high or CI-median patients had worse median OS, which can support the possibility of offering experimental treatment already at the first line for this group.

Role of Mitochondria-Cytoskeleton Interactions in the Regulation of Mitochondrial Structure and Function in Cancer Stem Cells

Despite the promise of cancer medicine, major challenges currently confronting the treatment of cancer patients include chemoresistance and recurrence. The existence of subpopulations of cancer cells, known as cancer stem cells (CSCs), contributes to the failure of cancer therapies and is associated with poor clinical outcomes. Of note, one of the recently characterized features of CSCs is augmented mitochondrial function. The cytoskeleton network is essential in regulating mitochondrial morphology and rearrangement, which are inextricably linked to its functions, such as oxidative phosphorylation (OXPHOS). The interaction between the cytoskeleton and mitochondria can enable CSCs to adapt to challenging conditions, such as a lack of energy sources, and to maintain their stemness. Cytoskeleton-mediated mitochondrial trafficking and relocating to the high energy requirement region are crucial steps in epithelial-to-mesenchymal transition (EMT). In addition, the cytoskeleton itself interplays with and blocks the voltage-dependent anion channel (VDAC) to directly regulate bioenergetics. In this review, we describe the regulation of cellular bioenergetics in CSCs, focusing on the cytoskeleton-mediated dynamic control of mitochondrial structure and function.

Flaming and fanning: The Spectrum of inflammatory influences in myelodysplastic syndromes

The myelodysplastic syndromes (MDS) represent neoplasms derived from the expansion of mutated clonal hematopoietic cells which often demonstrate aberrant differentiation potential with resultant cytopenias and a propensity to evolve into acute myelogenous leukemia. While multiple mutations have been identified which may serve as drivers of the MDS clone, there is accumulating evidence that MDS clones and subclones are subject to modulation by the marrow microenvironment and its inflammatory milieu. There is also a strong link between autoimmune disorders and MDS. In this review, we examine the role of inflammatory cytokines, toll like receptors, pyroptosis, stromal cells, and cellular inflammatory mediators in MDS initiation, propagation, and progression. These contributions in a background of mutational, epigenetic, and aging changes in the marrow are also reviewed. Such inflammatory mediators may be subject to therapeutic agents which will enhance suppression of the MDS clone with potential to improve therapeutic outcomes in this disease which is usually incurable in aged patients not eligible for stem cell transplantation.