Tumor Metabolism Research Articles

Bibliometric and visual analysis of human microbiome—breast cancer interactions: current insights and future directions

The composition of the gut microbiome differs from that of healthy individuals and is closely linked to the progression and development of breast cancer. Recent studies have increasingly examined the relationship between microbial communities and breast cancer. This study analyzed the research landscape of microbiome and breast cancer, focusing on 736 qualified publications from the Web of Science Core Collection (WoSCC). Publications in this field are on the rise, with the United States leading in contributions, followed by China and Italy. Despite this strong output, the centrality value of China in this field is comparatively low at ninth, highlighting a gap between the quantity of research and its global impact. This pattern is repetitively observed in institutional contributions, with a predominance of Western institutes among the top contributors, underscoring a potential research quality gap in China. Keyword analysis reveals that research hotspots are focused on the effect of microbiome on breast cancer pathogenesis and tumor metabolism, with risk factors and metabolic pathways being the most interesting areas. Publications point to a shift toward anti-tumor therapies and personalized medicine, with clusters such as “anti-tumor” and “potential regulatory agent” gaining prominence. Additionally, intratumor bacteria studies have emerged as a new area of significant interest, reflecting a new direction in research. The University of Helsinki and Adlercreutz H are influential institutions and researchers in this field. Current trends in microbiome and breast cancer research indicate a significant shift toward therapeutic applications and personalized medicine. Strengthening international collaborations and focusing on research quality is crucial for advancing microbiome and breast cancer research.

FRK exerts oncogenic effects by targeting NQO2 via exosomal miR-9-3p to regulate mitochondrial function.

The role of Fyn-related kinase (FRK) in promoting tumor progression and metabolism in non-small cell lung cancer (NSCLC) has been demonstrated in our earlier study, and here we further explored whether exosome could serve as a key player in the relevant regulatory mechanism. Exosomes were isolated from the culture medium of FRK-knockout (KO) cells and co-cultured with NSCLC cells, showing negative effects on cell proliferation, metastasis, metabolism, and mitochondrial function. Exosomal miR-9-3p was selected as an intermediate messenger through microRNA (miRNA) sequencing. The miR-9-3p inhibitor and exosome inhibitor GW4869 were then applied in the co-culture system to verify the contribution of exosomal miR-9-3p to cell malignant phenotype and mitochondrial function. Moreover, NQO2, a potential target of exosomal miR-9-3p, was also suggested to be involved in the regulation of mitochondrial functional status. In brief, this study revealed a novel molecular mechanism by which FRK promotes the malignant progression of NSCLC by targeting NQO2 via exosomal miR-9-3p to strengthen mitochondrial function.

Ursolic Acid Inhibits Glycolysis of Ovarian Cancer via KLF5/PI3K/AKT Signaling Pathway.

Glycolysis is one of the key metabolic reprogramming characteristics of ovarian cancer. Ursolic Acid (UA), as a natural compound, exerts a beneficial regulatory effect on tumor metabolism. In this study, we have confirmed through RNA-seq analysis and a series of in vitro and in vivo functional experiments that UA significantly inhibits ovarian cancer cell proliferation, promotes tumor apoptosis, and reduces glycolysis levels. Additionally, it demonstrates synergistic therapeutic effects with cisplatin in both in vitro and in vivo experiments. Furthermore, at the molecular level, we found that UA inhibits glycolysis in ovarian cancer by binding to the transcription factor KLF5 and blocking the transcriptional expression of the downstream PI3K/AKT signaling pathway, thereby exerting its therapeutic effect. In conclusion, our research indicates that UA can inhibit the proliferation, apoptosis, and glycolysis levels of ovarian cancer cells through the KLF5/PI3K/AKT signaling axis. Our findings offer a new perspective on the therapeutic application of the natural compound UA in ovarian cancer and support its potential development as a candidate for chemotherapy.

Cryo-EM structure of PML RBCC dimer reveals CC-mediated octopus-like nuclear body assembly mechanism

Promyelocytic leukemia protein (PML) nuclear bodies (NBs) are essential in regulating tumor suppression, antiviral response, inflammation, metabolism, aging, and other important life processes. The re-assembly of PML NBs might lead to an ~100% cure of acute promyelocytic leukemia. However, until now, the molecular mechanism underpinning PML NB biogenesis remains elusive due to the lack of structural information. In this study, we present the cryo-electron microscopy (cryo-EM) structure of the PML dimer at an overall resolution of 5.3 Å, encompassing the RING, B-box1/2 and part of the coiled-coil (RBCC) domains. The integrated approach, combining crosslinking and mass spectrometry (XL-MS) and functional analyses, enabled us to observe a unique folding event within the RBCC domains. The RING and B-box1/2 domains fold around the α3 helix, and the α6 helix serves as a pivotal interface for PML dimerization. More importantly, further characterizations of the cryo-EM structure in conjugation with AlphaFold2 prediction, XL-MS, and NB formation assays, help unveil an unprecedented octopus-like mechanism in NB assembly, wherein each CC helix of a PML dimer (PML dimer A) interacts with a CC helix from a neighboring PML dimer (PML dimer B) in an anti-parallel configuration, ultimately leading to the formation of a 2 µm membrane-less subcellular organelle.

Exosomal circular RNAs in tumor microenvironment: An emphasis on signaling pathways and clinical opportunities.

Exosomes can regulate the malignant progression of tumors by carrying a variety of genetic information and transmitting it to target cells. Recent studies indicate that exosomal circular RNAs (circRNAs) regulate multiple biological processes in carcinogenesis, such as tumor growth, metastasis, epithelial-mesenchymal transition, drug resistance, autophagy, metabolism, angiogenesis, and immune escape. In the tumor microenvironment (TME), exosomal circRNAs can be transferred among tumor cells, endothelial cells, cancer-associated fibroblasts, immune cells, and microbiota, affecting tumor initiation and progression. Due to the high stability and widespread presence of exosomal circRNAs, they hold promise as biomarkers for tumor diagnosis and prognosis prediction in blood and urine. In addition, designing nanoparticles targeting exosomal circRNAs and utilizing exosomal circRNAs derived from immune cells or stem cells provide new strategies for cancer therapy. In this review, we examined the crucial role of exosomal circRNAs in regulating tumor-related signaling pathways and summarized the transmission of exosomal circRNAs between various types of cells and their impact on the TME. Finally, our review highlights the potential of exosomal circRNAs as diagnostic and prognostic prediction biomarkers, as well as suggesting new strategies for clinical therapy.

Research advances in branched-chain amino acid metabolism in tumors.

The metabolic reprogramming of amino acids is an important component of tumor metabolism. Branched-chain amino acids (BCAAs) perform important functions in tumor progression. They are the important amino donor and are involved in the synthesis of various non-essential amino acids, nucleotides, and polyamines to satisfy the increased demand for nitrogen sources. This review summarizes the studies related to abnormalities in BCAA metabolism during tumorigenesis and the potential therapeutic targets. The expression of BCAA transporters was significantly upregulated in tumor cells, which increases BCAA uptake. High expression of the BCAA transaminases is prevalent in various tumors, however, the dehydrogenation step of BCAA catabolism is inhibited in tumors. This review shows that BCAA metabolic reprogramming is an important tumor metabolic feature, and metabolic genes of BCAAs play a crucial role in tumor metabolism, representing a good auxiliary target for early clinical diagnosis and treatment. In addition, BCAAs are indispensable for maintaining immune system function, and dietary supplementation with BCAAs can enhance the activity of immune cells. Therefore, BCAA supplementation in tumor patients may affect the interaction between the immune system and tumors.

Inhibition of Mitochondrial Bioenergetics and Hypoxia to Radiosensitize Diffuse Intrinsic Pontine Glioma.

Diffuse Intrinsic Pontine Gliomas (DIPG) and other H3K27M-mutated diffuse midline gliomas (DMGs) are brain tumors that primarily affect children. Radiotherapy is the standard of care but only provides temporary symptomatic relief due to radioresistance. While hypoxia is a major driver of radioresistance in other tumors, there is no definitive evidence that DIPGs are hypoxic. DIPGs often contain histone mutations, which alter tumor metabolism and are also associated with radioresistance. Our objective was to identify the metabolic profiles of DIPG cells, detect hypoxia signatures, and uncover metabolism-linked mechanisms of radioresistance to improve tumor radiosensitivity. Using DIPG models combined with clinical datasets, we examined mitochondrial metabolism and signatures of hypoxia. We explored DIPG reliance on mitochondrial metabolism using extracellular flux assays and targeted metabolomics. In vitro and in vivo models were used to explore the mechanisms of targeting mitochondrial bioenergetics and hypoxia for radiosensitization. Treatment-induced transcriptomics and metabolomics were also investigated. Comprehensive analyses of DIPG cells show signatures of enhanced oxidative phosphorylation (OXPHOS). We also identified increased expression of specific OXPHOS related genes and signatures of hypoxia gene expression in datasets obtained from DIPG patients. We found the presence of hypoxia in orthotopic mouse models bearing DIPG tumors. These findings enabled us to develop a proof-of-concept treatment strategy to enhance radiosensitivity of DIPGs in vitro and in animal models. DIPG cells rely on mitochondrial metabolism for growth, and targeting mitochondria disrupts bioenergetics, alleviates hypoxia, and enhances radiosensitivity. These findings warrant further exploration of OXPHOS inhibition as a radiosensitizing strategy for DIPG treatment.

Protein kinase A and local signaling in cancer.

Protein kinase A (PKA) is a basophilic kinase implicated in the modulation of many cell-signaling and physiological processes. PKA also contributes to cancer-relevant events such as growth factor action, cell cycle control, cell migration and tumor metabolism. Germline and somatic mutations in PKA, gene amplifications, and chromosome rearrangements that encode kinase fusions, are linked to a growing number of malignant neoplasms. Mislocalization of PKA by exclusion from A-Kinase Anchoring Protein (AKAP) signaling islands further underlies cancer progression. This article highlights the influence of AKAP signaling and local kinase action in selected hallmarks of cancer. We also feature the utility of kinase inhibitor drugs as frontline and future anti-cancer therapies.

Responsive plasmonic hybrid nanorods enables metabolism reprogramming via cuproptosis-photothermal combined cancer therapy

Abnormal tumor metabolism leads to tumor growth, metastasis, and recurrence, reprogramming tumor metabolism and activating potent anti-tumor immune response have been demonstrated to have good therapeutic effects on tumor elimination. Copper-based nanomaterials involved in cuproptosis show great prospects in these two aspects, but their efficiency is restricted by Cu homeostasis and the toxicity of the chelator. Here, the pH-responsive AuNRs@Cu2O core-shell plasmonic hybrid nanorods (ACNRs) have been successfully fabricated to realize microenvironment-controlled release at the tumor site for the combined therapy of cuproptosis and photothermal treatment. The AuNRs core exhibited excellent NIR-II photothermal property, which boost the intracellular concentration of copper to trigger severe cuproptosis and induce immunogenic cell death of tumor cells. In vivo studies demonstrated the ACNR exhibited efficient tumor therapy for primary, metastatic, and recurrent tumors. ACNRs-induced cuproptosis and PTT were capable of reprogramming energy metabolism, leading to a decreased production of lactic acid. This potential of metabolic reprogramming assisted in reshaping the immunosuppressive tumor microenvironment to facilitate the infiltration of immune cells and boost the immune responses triggered by PTT. The therapeutic mechanism was further verified by metabolomics analysis, which indicated that ACNRs + PTT treatment led to the inhibition of the Pentose Phosphate Pathway and Glycolysis pathways in tumor cells. The suppression of glycolytic reduced ATP synthesis, thereby hindering energy-dependent copper efflux, which in turn promoted cuproptosis. Taken together, this study offers promising insights for cuproptosis-based cancer treatment and sheds new light on nanomedicine-mediated metabolic modulation for future tumor therapy.

Uncovering the protective role of lipid droplet accumulation against acid-induced oxidative stress and cell death in osteosarcoma

Extracellular acidosis stemming from altered tumor metabolism promotes cancer progression by enabling tumor cell adaptation to the hostile microenvironment. In osteosarcoma, we have previously shown that acidosis increases tumor cell survival alongside substantial lipid droplet accumulation. In this study, we explored the role of lipid droplet formation in mitigating cellular stress induced by extracellular acidosis in osteosarcoma cells, thereby enhancing tumor survival during progression. Specifically, we examined how lipid droplets shield against reactive oxygen species induced by extracellular acidosis. We demonstrated that lipid droplet biogenesis is critical for acid-exposed tumor cell survival, as it starts shortly after acid exposure (24 h) and inversely correlates with ROS levels (DCFH-DA assay), lipid peroxidation (Bodipy assay), and the antioxidant response, as also revealed by NRF2 transcript. Additionally, extracellular metabolites, such as lactate, and interaction with mesenchymal stromal cells within the tumor microenvironment intensify lipid droplet build-up in osteosarcoma cells. Critically, upon targeting two key proteins implicated in LD formation - PLIN2 and DGAT1 - cell viability significantly declined while ROS production escalated. In summary, our findings underscore the vital reliance of acid-exposed tumor cells on lipid droplet formation to scavenge oxidative stress. We conclude that the rewiring of lipid metabolism driven by microenvironmental cues is of paramount importance for the survival of metabolically altered osteosarcoma cells in acidic condition. Overall, we suggest that targeting key members of lipid droplet biogenesis may eradicate more aggressive and resistant tumor cells, uncovering potential new treatment strategies for osteosarcoma.

Abstract A011: Assessing pro-tumorigenicity of the aging microenvironment in a murine ovarian cancer model

Abstract Over 70% of high-grade serous ovarian cancer (HGSOC) patients are diagnosed after age 55 and the average patient who succumbs to HGSOC is 70 years old. Despite this, the majority of ovarian cancer studies, and cancer studies generally, utilize young mice that are more representative of human children. This approach overlooks age as a variable, despite its status as a top risk factor for cancer. Our preliminary studies reveal tumor burden and disease severity is significantly higher in aged mice compared to young animals. We have developed an epithelial cell line derived from C57BL/6 oviducts and used CRISPR-Cas9 genome editing to establish tumorigenic lines for syngeneic studies. One line harbors Trp53, Pten, and Brca2 deletions, is tumorigenic, and can be serially passaged in vitro. When injected intraperitoneally (IP) into 8-week and 56-week-old mice, equating to approximately 10- and 45-year-old humans respectively, a stark increase in tumor mass was evident in aged mice. Furthermore, the aged mice succumbed to disease at a faster rate after inoculation than the young group, where all mice succumbed to disease within 1-month of IP injection compared to some young mice surviving up to 3 months after injection. These findings, combined with epidemiologic data, suggest a metastatic driver in the aged microenvironment that facilitates worsened ovarian cancer progression. We are investigating two factors that change with age, (1) a suppressed immune system and (2) age-related changes to adipose tissue, as possible mechanisms driving this difference. Histologic analysis of tumors from each cohort showed decreased cleaved caspase-3 in aged tumors, indicating a reduction in tumor cell killing in older animals. Characterization of the pre-cancerous, tumor-naive microenvironment via flow cytometry and cytokine array have revealed that aged mice microenvironment is highly inflamed and features changes in immune populations and inflammatory states. Meanwhile, total RNA-sequencing of tumors harvested from aged and young mice showed minimal changes, but DEGs point to possible roles of fat transport and metabolism in these aged tumors, indicated by upregulated CD36 and lipoprotein lipase. Follow-up ex vivo experiments had demonstrated increased adhesion and proliferation of the previously described murine cancer cells to fat pads when cultured in vitro. When assessing tumor-naive fat depots, aged adipose tissue is comprised of significantly larger adipocytes and the omentum, a common secondary site of ovarian cancer and fatty organ, was found to have increased phospholipid content in older animals. Both findings point to a change in metabolic function in aged mice. Our preliminary findings indicate an important role of the aged microenvironment in driving enhanced diseases progression in older individuals and identifying the mechanisms behind this phenotype are critical; an improved understanding of how age affects HGSOC progression could enable the development of treatment strategies to prevent cancer cells from establishing in the peritoneum. Citation Format: Katherine A. Cummins, Ronny Drapkin. Assessing pro-tumorigenicity of the aging microenvironment in a murine ovarian cancer model [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A011.

Exploring the impact of mitochondrial-targeting anthelmintic agents with GLUT1 inhibitor BAY-876 on breast cancer cell metabolism

BackgroundCancer cells alter their metabolic phenotypes with nutritional change. Single agent approaches targeting mitochondrial metabolism in cancer have failed due to either dose limiting off target toxicities, or lack of significant efficacy in vivo. To mitigate these clinical challenges, we investigated the potential utility of repurposing FDA approved mitochondrial targeting anthelmintic agents, niclosamide, IMD-0354 and pyrvinium pamoate, to be combined with GLUT1 inhibitor BAY-876 to enhance the inhibitory capacity of the major metabolic phenotypes exhibited by tumors.MethodsTo test this, we used breast cancer cell lines MDA-MB-231 and 4T1 which exhibit differing basal metabolic rates of glycolysis and mitochondrial respiration, respectively. Metabolic characterization was carried out using Seahorse XFe96 Bioanalyzer and statistical analysis was carried out via ANOVA.ResultsHere, we found that specific responses to mitochondrial and glycolysis targeting agents elicit responses that correlate with tested cell lines basal metabolic rates and fuel preference, highlighting the potential to cater metabolism targeting treatment regimens based on specific tumor nutrient handling. Inhibition of GLUT1 with BAY-876 potently inhibited glycolysis in both MDA-MB-231 and 4T1 cells, and niclosamide and pyrvinium pamoate perturbed mitochondrial respiration that resulted in potent compensatory glycolysis in the cell lines tested.ConclusionIn this regard, combination of BAY-876 with both mitochondrial targeting agents resulted in inhibition of compensatory glycolysis and subsequent metabolic crisis. These studies highlight targeting tumor metabolism as a combination treatment regimen that can be tailored by basal and compensatory metabolic phenotypes.

Oncogenic cholesterol rewires lipid metabolism in hepatocellular carcinoma via the CSNK2A1-IGF2R Ser2484 axis

IntroductionAlcohol consumption and hepatitis B virus (HBV) infection are common risk factors for hepatocellular carcinoma (HCC). However, few studies have focused on elucidating the mechanisms of HCC with combined alcohol and HBV etiology. ObjectivesWe aimed to investigate the molecular features of alcohol and HBV on HCC and to seek out potential therapeutic strategies. MethodsTwo independent cohorts of HCC patients (n = 539 and n = 140) were included to investigate HCC with synergetic alcohol and HBV (AB-HCC) background. Patient-derived cell lines, organoids, and xenografts were used to validate the metabolic fragile. High-throughput drug screening (1181 FDA-approved anticancer drugs) was leveraged to explore the potential therapeutic agents. ResultsHere, we delineated AB-HCC as a distinctive metabolic subtype, hallmarked by oncogenic cholesterol, through the integration of clinical cohorts, proteomics, phosphoproteomics, and spatial transcriptome. Mechanistically, our findings revealed that cholesterol directly binds to CSNK2A1 (Casein Kinase 2 Alpha 1), augmenting its kinase activity and leading to phosphorylation of IGF2R (Insulin-Like Growth Factor 2 Receptor) at Ser2484. This cascade rewires lipid-driven mitochondrial oxidative phosphorylation, spawns reactive oxygen species measured by malondialdehyde assay, and perpetuates a positive feedback loop for cholesterol biosynthesis, ultimately culminating in tumorigenesis. Initial transcriptional activation of CSNK2A1 is driven by upregulation of RAD21 in AB-HCC. Our cholesterol profiling exposes AB-HCC’s compensatory mechanism of AB-HCC, which capitalizes on both uptake and biosynthesis of cholesterol to confer survival edge. Moreover, high-throughput drug screening coupled with in vivo validation has uncovered the susceptibilities of AB-HCC, which can be effectively addressed by a combination of dietary cholesterol restriction and oral administration of Fostamatinib. The CSNK2A1-mediated cholesterol biosynthesis pathway has been implicated in various cancers characterized by cholesterol metabolism. ConclusionThese findings not only pinpoint the oncogenic metabolite cholesterol as a hidden culprit in AB-HCC subtype, but also enlighten a novel combination strategy to rejuvenate tumor metabolism.

Programmable Nanomodulators for Precision Therapy, Engineering Tumor Metabolism to Enhance Therapeutic Efficacy.

Tumor metabolism is crucial in the continuous advancement and complex growth of cancer. The emerging field of nanotechnology has made significant strides in enhancing the understanding of the complex metabolic intricacies inherent to tumors, offering potential avenues for their strategic manipulation to achieve therapeutic goals. This comprehensive review delves into the interplay between tumor metabolism and various facets of cancer, encompassing its origins, progression, and the formidable challenges posed by metastasis. Simultaneously, it underscores the classification of programmable nanomodulators and their transformative impact on enhancing cancer treatment, particularly when integrated with modalities such as chemotherapy, radiotherapy, and immunotherapy. This review also encapsulates the mechanisms by which nanomodulators modulate tumor metabolism, including the delivery of metabolic inhibitors, regulation of oxidative stress, pH value modulation, nanoenzyme catalysis, nutrient deprivation, and RNA interference technology, among others. Additionally, the review delves into the prospects and challenges of nanomodulators in clinical applications. Finally, the innovative concept of using nanomodulators to reprogram metabolic pathways is introduced, aiming to transform cancer cells back into normal cells. This review underscores the profound impact that tailored nanomodulators can have on tumor metabolic, charting a path toward pioneering precision therapies for cancer.

TMET-20. A METABOLIC BIOMARKER IN GLIOBLASTOMA: A PROMISING APPLICATION OF CO-POLARIZED [1-13C]PYRUVATE AND [1-13C]DEHYDROASCORBATE

Abstract BACKGROUND Noninvasive biomarkers for treatment response in glioblastoma are needed to improve patient outcomes. Our understanding of redox biology in treatment resistance is rapidly evolving, and interrogation of tumor metabolism represents an ideal opportunity to meet this need. In this study, the utility of co-hyperpolarized [1-13C]pyruvate and [1-13C]dehydroascorbate (HP PA/DHA) to simultaneously evaluate brain tumor metabolism and oxidative stress in orthotopically implanted mice is investigated. METHODS To characterize HP PA/DHA, mice were treated with 0-4mM diethyl maleate and 1D slab dynamic acquisitions were performed over the mouse brain. As an initial evaluation of the utility of HP DHA/PA in brain tumors, athymic nude mice (n=8) underwent orthotopic U87 glioblastoma implantation. After treatment with 8Gy in one fraction, mice were injected with HP DHA/PA dissolved in D2O. T2-weighted and 13C Chemical Shift Imaging sequences were obtained on a 3T MRI using a quadrature double-tuned 1H/13C volume coil. RESULTS HP DHA/PA detected differential lactate and vitamin C generation over the mouse brain. Treatment with diethyl maleate, which depletes the cofactor glutathione, diminished fractional vitamin C generation (0.1 vs 0.03, p=0.0009). Elevation in tumor lactate generation was seen in untreated (125.1±17.6µM, p=0.005) and radiated mice (149.4±32.6µM, p=0.01). Treatment with radiation generated higher vitamin C concentrations in tumors relative to contralateral brain (46.8±4.8µM, p=0.002). Radiated tumors were distinguished by higher ratio of lactate to vitamin C compared to untreated tumor controls (3.7 vs 2.5, p=0.07), and the same relationship was preserved between treated and untreated non-tumor brain. CONCLUSION The ratio of vitamin C/lactate detects the metabolic effects of radiation in brain tumors, inspiring its’ potential as a biomarker for treatment response. To further characterize these findings, examination of survival and modulation of radiosensitivity are ongoing.

NIMG-80. IMPACT OF KETOGENIC DIET ON MOLECULAR METABOLIC IMAGING WITH [18F]FDG AND [18F]DASA-23 POSITRON EMISSION TOMOGRAPHY IN A PATIENT WITH GLIOBLASTOMA

Abstract The standard-of-care for neuroimaging in patients with glioblastoma is contrast-enhanced MRI, which does not provide tumor metabolism information. Although [18F]FDG PET is used to image tumor metabolism in many solid organ cancers, it has limited benefit in atients with brain tumors due to the high level of glucose uptake in normal brain cells. [18F]DASA-23 is a novel PET radiotracer that assesses the levels of pyruvate kinase M2 (PKM2), a protein highly expressed in cancer cells, which undergo aberrant glycolysis. Despite [18F]DASA-23 having a higher tumor-to-background ratio (TBR) of standardized uptake values (SUVs) in the brain compared to [18F]FDG, both may be susceptible to altered carbohydrate metabolism in the setting of a ketogenic diet (KD). We report the case of a patient with glioblastoma on a KD, whose [18F]FDG and [18F]DASA-23 PET brain scans were limited in identifying disease progression (PD). Background was defined as the white matter contralateral to the tumor, at the level of the centrum semiovale, for TBR of SUVmax. A 39-year-old man was diagnosed with right temporal glioblastoma after previous diagnoses of grade 2 gliofibrillary oligodendroglioma (age 20) and grade 3 anaplastic oligodendroglioma (age 22). He began a KD after the glioblastoma diagnosis. 21 months later, TBR on [18F]DASA-23 PET was 1.38. One month later, surveillance brain MRI showed PD. Ten days later, TBR on [18F]FDG PET was 1.03. The patient died 15 months later. Despite MRI-based PD, the TBR of each radiotracer was not markedly elevated, although the [18F]DASA-23 TBR 1-month pre-PD was 34% greater than the [18F]FDG PET TBR 10-days post-PD. This may suggest a limitation of metabolic imaging by PET in the setting of a KD, and provide an opportunity to develop novel PET radiotracers that are not susceptible to the patient’s diet.

EXTH-42. GLIOMA-DERIVED CD200 PROMOTES TUMOR GROWTH AND SUPPRESSES NK CELL AND CD8 T CELL ANTI-GLIOMA ACTIVITY

Abstract Immune-checkpoint inhibitors, such as anti-PD1 and anti-CTLA4, have emerged as promising therapeutic options for several malignancies yet show little efficacy against malignant brain cancers. CD200 is a newly recognized immune-checkpoint which is expressed by a marid of cell types, modulating immune homeostasis through multiple receptors. There is currently limited information regarding CD200 effects in brain tumors. Furthermore, while it is well accepted that CD200 binding to its inhibitory receptor induces a pro-tumorigenic environment through its ability to suppress immune responses, there are increasing evidence that CD200 could also have anti-tumor characteristics. Here we evaluated the role of tumor-derived CD200 on anti-glioma immunity. We demonstrate that CD200 is expressed across glioma types, is shed from tumor cells, and increases over time in serum of patients undergoing immunotherapy. Transcriptomic analysis of CD200 knockout (KO) glioma models reveals that glioma-derived CD200 significantly modifies the glioma tumor microenvironment (TME), not only through immune regulation but also through immune-independent pathways, such as tumor metabolism. Furthermore, we show that CD200 KO gliomas have reduced proliferation and are rejected by their hosts. Downstream analysis revealed that rejection of CD200 KO gliomas relied on a functional adoptive immune system, while decreased proliferation was linked to reduced CXCL10 production by the CD200 KO gliomas. Additionally, we demonstrate that glioma-mediated CD200 strongly suppresses anti-glioma NK cell function within the tumor microenvironment (TME), while secreted CD200 inhibits the priming of antigen-specific CD8 T cells in the lymphatic. Notably, NK cells were essential for the initial rejection of CD200 KO gliomas, while CD8 T cells played a critical role in establishing durable anti-tumor responses. Our work provides new mechanistic insights on glioma-derived CD200-mediated immunosuppression and an untapped potential for targeting CD200 by immunotherapies for malignant gliomas.

BIOM-25. MOLECULAR PROFILING PREDICTS EARLY AND LATE PROGRESSION IN GLIOBLASTOMA

Abstract Patients with glioblastoma experience a wide variation in response to standard treatment, with nearly 30% experiencing tumour progression during treatment, and nearly 6% surviving more than 5 years. To date, there are few non-invasive clinical biomarkers to predict response to first – line treatment. Chemical exchange saturation transfer (CEST) MRI may have the potential to fill this gap. CEST MRI is sensitive to treatment-induced changes and changes in tumor metabolism. Our team has obtained CEST data for patients before, during and after the end of standard chemoradiation treatment, and found that CEST provides markers of early response and can identify early, standard and late progressors before treatment initiation. In this study, we aimed to establish molecular profiles of early, standard and late progressors with IDH wild-type glioblastoma. Patients (n=180) with primary, IDH wild-type glioblastoma were imaged with CEST-MRI at multiple time points throughout standard chemoradiation treatment. DNA and RNA were co-extracted from matched normal and tumour pairs and processed for whole genome sequencing, enzymatic methyl-seq and gene expression analysis using Nanostring. Clinical variables such as age, extent of resection, sex, ECOG status and MGMT promoter methylated were also collected. A survival analysis was conducted using the Kaplan-Meier method with log-rank tests. Univariate and multi-variate hazard ratios for clinical variables were calculated by fitting Cox Proportional Hazards Models. Early progressors reported a median progression-free survival (PFS) of 142 days compared to 832 days in late progressors (p<0.0001). Early progressors also harbored distinct and statistically significant differences in gene expression and genomic alterations, namely in DNA damage repair, glucose transport and arginine metabolism pathways. A gene signature was prognostic of PFS and overall survival. Collectively, this data has the potential to serve as a radiogenomic biomarker to assess treatment response before or within early phases of treatment and allow for individual tailoring of the treatment plan.

NIMG-69. INTERROGATION OF GLIOBLASTOMA FATTY-ACID SYNTHESIS AND METABOLISM WITH DEUTERIUM METABOLIC IMAGING

Abstract Glioblastoma, an invariably lethal brain tumor, undergoes marked metabolic alterations during tumorigenesis and is extraordinarily difficult to treat. Detecting recurrence after treatment and understanding metabolic alterations within the tumor microenvironment are extremely challenging. An exciting and emerging imaging methodology, deuterium metabolic imaging (DMI), detects metabolic adaptations via non-radioactively labeled deuterated substrates. This study developed approaches to image lipid synthesis with deuterium oxide (D2O) and metabolism with D31-palmitate (D31-Pal) in glioblastoma. A fatty-acid phantom was generated for characterization of lipid DMI signal at 12 T. DMI was performed in mice orthotopically implanted with GL261 glioblastoma utilizing either orally administered D31-Pal or D2O and was correlated with pharmacokinetic metabolic measurements from mouse serum. Mice were either orally gavaged with an emulsion of D31-Pal prior to imaging or provided 16% D2O for ad libitum consumption following tumor implantation. Although D2O administration resulted in robust enrichment of lipid signal in GBM, D31-Pal uptake and metabolism were not significantly detected within intracranial tumors. Interestingly, D31-Pal uptake and metabolism were detected in normal tissues, indicating preferential utilization of fatty acids in non-neoplastic tissues. These findings suggest de novo lipogenesis within GBM, rather than uptake of administered long chain fatty acids, is the preferential pathway for cellular lipids. DMI can assist in interrogating GBM fatty-acid synthesis and metabolism, as well as furthering our understanding of lipid distribution within the body by providing a non-invasive scaffold for dynamic interrogation of fatty-acid distribution in an oncologic model. Developing a non-invasive method for characterization of tumor fatty-acid synthesis and metabolism may improve our understanding of tumor metabolism and could dynamically guide selection of patient-tailored metabolic therapies in the future.

IMMU-21. OVEREXPRESSING CAR T-CELL GLUCOSE TRANSPORTER TO ENHANCE ANTI-TUMOR ACTIVITY IN GLIOBLASTOMA

Abstract INTRODUCTION Despite aggressive interventions, Glioblastoma (GBM) remains as a challenge for neuro-oncologists. Standard treatments are often followed by disease recurrence. Adoptive cell therapies have emerged as a viable therapeutic for brain malignancies. CAR-T cell therapy has generated substantial interest because of its efficacy and specificity in treating various cancers. Despite these efficacies, studies reveal limitations of CAR-T therapy due to the altered metabolic environment in GBM. GBM tumors shift towards aerobic glycolysis, regardless of oxygen availability leading to massive glucose consumption. This results in impeding T-cell glycolysis and activation. OBJECTIVE The GBM microenvironment provides local restraints via metabolic competition suppressing antitumor immunity, specifically inhibiting infiltration and tumoricidal functions of host and adoptively transferred tumor-reactive T-cells. In our study, we manipulated the metabolic fitness of the therapeutic T-cells to enhance their tumoricidal activity, by overexpressing glucose transporter GLUT1 and GLUT3. We show that this manipulation can enhance their anti-tumor activity. METHODS The T-cell glucose metabolic pathway was modulated via glucose transporter overexpression. The functionality of metabolically modified T-cells was investigated in murine and human models. RESULTS We demonstrated that tumor cells impose glucose restriction when competing for glucose with T-cells leading to T-cell hypo responsiveness. Overexpression of glucose transporters such as Glut1 and Glut3 increased T-cell glucose utilization and provide survival advantage leading to enhanced T-cell activation in glucose-restricted conditions. The metabolic modifications regulate T-cell efficacy by enhancing intra-tumoral trafficking. We tested this approach in the context of CD70CAR T cell therapy. It was established that glucose transporter overexpression in CD70 CAR T-cells not only improves intracranial tumor invasion but also elicit functional anti-tumor cell response thus improving survival. CONCLUSIONS This study integrates fundamental concepts of tumor and immune metabolism in the design of immunotherapy and confirms that immunometabolism represents a viable target for new cancer therapy to treat brain tumors.