Publications by authors named "Pedro Lowenstein"

A critical challenge in glioma treatment is detecting tumour infiltration during surgery to achieve safe maximal resection. Unfortunately, safely resectable residual tumour is found in the majority of patients with glioma after surgery, causing early recurrence and decreased survival. Here we present FastGlioma, a visual foundation model for fast (<10 s) and accurate detection of glioma infiltration in fresh, unprocessed surgical tissue.

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Oncostreams are self-organized structures formed by spindle-like, elongated, self-propelled cells recently described in glioblastomas and especially in gliosarcomas. Cells within these structures either move as large clusters in one main direction, flocks, or as linear, intermingling collections of cells advancing in opposite directions, streams. Round, passive cells are also observed, either inside or segregated from the oncostreams.

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Article Synopsis
  • mRNA vaccines, initially developed for cancer control, have emerged as crucial tools in fighting infectious diseases, particularly during the COVID-19 pandemic.
  • The review explores advancements in mRNA vaccine technology, including personalized vaccines showing promise against tough cancers like pancreatic cancer and melanoma, and considers their potential against difficult tumors like glioblastoma.
  • A comprehensive roadmap is presented for using mRNA vaccines to enhance cancer immunotherapy, with a focus on glioblastoma treatments through innovative combinations of RNA science and immunotherapies.
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Brain tumors in children and adults differ greatly in patient outcomes and responses to radiotherapy and chemotherapy. Moreover, the prevalence of recurrent mutations in histones and chromatin regulatory proteins in pediatric and young adult gliomas suggests that the chromatin landscape is rewired to support oncogenic programs. These early somatic mutations dysregulate widespread genomic loci by altering the distribution of histone post-translational modifications (PTMs) and, in consequence, causing changes in chromatin accessibility and in the histone code, leading to gene transcriptional changes.

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The majority of primary brain tumors are gliomas, among which glioblastoma multiforme (GBM) is the most common malignant brain tumor in adults. GBM has a median survival of 18-24 months, and despite extensive research it remains incurable, thus novel therapies are urgently needed. The current standard of care is a combination of surgery, radiation, and chemotherapy, but still remains ineffective due to the invasive nature and high recurrence of gliomas.

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Histone deacetylases (HDACs) have a wide range of targets and can rewire both the chromatin and lipidome of cancer cells. In this study, we show that valproic acid (VPA), a brain penetrant anti-seizure medication and histone deacetylase inhibitor, inhibits the growth of IDH1 mutant tumors in vivo and in vitro, with at least some selectivity over IDH1 wild-type tumors. Surprisingly, genes upregulated by VPA showed no enhanced chromatin accessibility at the promoter, but there was a correlation between VPA-downregulated genes and diminished promoter chromatin accessibility.

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Article Synopsis
  • Mutant isocitrate dehydrogenase 1 (mIDH1) creates excess 2-hydroxyglutarate (2HG), leading to changes in gene expression and making mIDH1 gliomas more resilient to DNA damage and radiation.* -
  • Research found mIDH1 glioma cells showed reduced mitochondrial metabolism and increased autophagy, which became their main energy source, indicating they rely heavily on autophagy for survival.* -
  • Blocking autophagy weakened the growth of mIDH1 glioma cells and, when combined with radiation, enhanced treatment effectiveness, suggesting targeting autophagy could improve therapies for mIDH1 glioma patients.*
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Glioblastoma (GBM) remains a challenge in Neuro-oncology, with a poor prognosis showing only a 5% survival rate beyond two years. This is primarily due to its aggressiveness and intra-tumoral heterogeneity, which limits complete surgical resection and reduces the efficacy of existing treatments. The existence of oncostreams-neuropathological structures comprising aligned spindle-like cells from both tumor and non-tumor origins- is discovered earlier.

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Article Synopsis
  • - Recent clinical trials for H3K27-altered diffuse midline gliomas (DMGs) are showing promising results, indicating potential advancements in treatment.
  • - The text identifies three key challenges: improving experimental models to include immune and brain-specific factors, fostering collaboration between researchers, clinicians, and the industry, and optimizing clinical processes like biopsy and drug delivery.
  • - Emphasizes that extensive collaboration is crucial for enhancing our understanding of DMGs, as well as improving diagnostics and therapies for these tumors.
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  • This study focuses on a clinical trial exploring the use of adenoviral vectors to enhance immune responses in patients with high-grade gliomas, which are aggressive brain tumors with poor treatment outcomes.
  • The trial involved administering two specific vectors (HSV1-TK and Flt3L) into the tumor site of treatment-naive adults, using a dose-finding approach to evaluate safety and potential effectiveness.
  • Conducted at the University of Michigan, the study aimed to assess how these vectors could stimulate anti-tumor immunity and improve patient prognosis after standard treatment protocols.
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Gliomas are the most prevalent and devastating primary malignant brain tumors in adults. Despite substantial advances in understanding glioma biology, there have been no regulatory drug approvals in the US since bevacizumab in 2009 and tumor treating fields in 2011. Recent phase III clinical trials have failed to meet their prespecified therapeutic primary endpoints, highlighting the need for novel therapies.

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Pediatric high-grade gliomas (pHGGs) are diffuse and highly aggressive CNS tumors which remain incurable, with a 5-year overall survival of less than 20%. Within glioma, mutations in the genes encoding the histones H3.1 and H3.

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Collective behavior spans several orders of magnitude of biological organization, from cell colonies to flocks of birds. We used time-resolved tracking of individual glioblastoma cells to investigate collective motion in an ex vivo model of glioblastoma. At the population level, glioblastoma cells display weakly polarized motion in the (directional) velocities of single cells.

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Collective cell behavior contributes to all stages of cancer progression. Understanding how collective behavior emerges through cell-cell interactions and decision-making will advance our understanding of cancer biology and provide new therapeutic approaches. Here, we summarize an interdisciplinary discussion on multicellular behavior in cancer, draw lessons from other scientific disciplines, and identify future directions.

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Molecular classification has transformed the management of brain tumors by enabling more accurate prognostication and personalized treatment. However, timely molecular diagnostic testing for patients with brain tumors is limited, complicating surgical and adjuvant treatment and obstructing clinical trial enrollment. In this study, we developed DeepGlioma, a rapid (<90 seconds), artificial-intelligence-based diagnostic screening system to streamline the molecular diagnosis of diffuse gliomas.

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Development of spatial-integrative pre-clinical models is needed for glioblastoma, which are heterogenous tumors with poor prognosis. Here, we present an optimized protocol to generate three-dimensional ex vivo explant slice glioma model from orthotopic tumors, genetically engineered mouse models, and fresh patient-derived specimens. We describe a step-by-step workflow for tissue acquisition, dissection, and sectioning of 300-μm tumor slices maintaining cell viability.

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Purpose: Mutant isocitrate dehydrogenase 1 (mIDH1) alters the epigenetic regulation of chromatin, leading to a hypermethylation phenotype in adult glioma. This work focuses on identifying gene targets epigenetically dysregulated by mIDH1 to confer therapeutic resistance to ionizing radiation (IR).

Experimental Design: We evaluated changes in the transcriptome and epigenome in a radioresistant mIDH1 patient-derived glioma cell culture (GCC) following treatment with an mIDH1-specific inhibitor, AGI-5198.

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Epigenetic remodeling is a molecular hallmark of gliomas, and it has been identified as a key mediator of glioma progression. Epigenetic dysregulation contributes to gliomagenesis, tumor progression, and responses to immunotherapies, as well as determining clinical features. This epigenetic remodeling includes changes in histone modifications, chromatin structure, and DNA methylation, all of which are driven by mutations in genes such as histone 3 genes (H3C1 and H3F3A), isocitrate dehydrogenase 1/2 (IDH1/2), α-thalassemia/mental retardation, X-linked (ATRX), and additional chromatin remodelers.

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Introduction: High-grade gliomas (HGG) are the most common malignant primary brain tumors in adults, with a median survival of ~18 months. The standard of care (SOC) is maximal safe surgical resection, and radiation therapy with concurrent and adjuvant temozolomide. This protocol remains unchanged since 2005, even though HGG median survival has marginally improved.

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Glioblastoma (GBM), an aggressive high-grade glial tumor, is resistant to therapy and has a poor prognosis due to its universal recurrence rate. GBM cells interact with the non-cellular components in the tumor microenvironment (TME), facilitating their rapid growth, evolution, and invasion into the normal brain. Herein we discuss the complexity of the interactions between the cellular and non-cellular components of the TME and advances in the field as a whole.

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Glioma stem cells (GSC) exhibit plasticity in response to environmental and therapeutic stress leading to tumor recurrence, but the underlying mechanisms remain largely unknown. Here, we employ single-cell and whole transcriptomic analyses to uncover that radiation induces a dynamic shift in functional states of glioma cells allowing for acquisition of vascular endothelial-like and pericyte-like cell phenotypes. These vascular-like cells provide trophic support to promote proliferation of tumor cells, and their selective depletion results in reduced tumor growth post-treatment in vivo.

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The preclinical and clinical development of novel immunotherapies for the treatment of central nervous system (CNS) tumors is advancing at a rapid pace. High-grade gliomas (HGG) are aggressive tumors with poor prognoses in both adult and pediatric patients, and innovative and effective therapies are greatly needed. The use of cytotoxic chemotherapies has marginally improved survival in some HGG patient populations.

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