TMOD-07. HUMAN DIFFUSE MIDLINE GLIOMA AVATARS AS A PLATFORM TO SEARCH FOR NOVEL THERAPEUTIC TARGETS

Abstract Diffuse midline glioma is the leading cause of brain tumor death among the pediatric population. Drugs that show notable promise in preclinical models inevitably fail to demonstrate efficacy in clinical trials, likely due to the inadequacy of preclinical models. We have recently proposed glioblastoma models derived from human induced pluripotent stem cells (hiPSCs) genetically engineered with different combinations of glioblastoma-associated genetic alterations as a platform to search for therapeutic targets. These glioblastoma avatars authentically recapitulated the different pathobiology of glioblastoma subtypes, depending on what genetic alterations to be introduced. To investigate the biology and to develop novel therapeutics for diffuse midline glioma with H3K27M mutation, we have established a novel model by introducing H3.3 K27M mutation together with one of the most common concurrent genetic alterations, TP53 R248Q mutation, into hiPSCs through CRISPR/Cas9 genome engineering. Orthotopic engraftment of the neural progenitor cells derived from these edited hiPSCs formed diffusely invasive brainstem tumors with histological features of the diffuse midline glioma. These tumor avatars presented a global reduction in H3K27me3 accompanied by the expression of H3K27M. Transcriptome analyses of these models revealed that these avatars with H3K27M cluster apart from the pediatric glioma samples without this particular mutation, and that they present signatures of oligodendroglial progenitor differentiation as discovered in patient samples with this mutation. Using these models faithfully recapitulating histology and pathobiology of the patient tumors, we have performed drug screening and confirmed that their sensitivity to known drugs, including an EZH2 inhibitor and histone deacetylase inhibitors. On these faithful human avatars of diffuse midline glioma with H3K27M, we have applied bioinformatics algorithms of drug sensitivity prediction aiming at developing novel therapeutics for this devastating pediatric glioma.

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DIPG-68. ALPHA-THALASSEMIA X-LINKED MENTAL RETARDATION PROTEIN (ATRX) LOSS-OF-FUNCTION IN A MOUSE MODEL OF DIFFUSE INTRINSIC PONTINE GLIOMA

Neuro-Oncology ◽

10.1093/neuonc/noaa222.111 ◽

2020 ◽

Vol 22 (Supplement_3) ◽

pp. iii300-iii300

Author(s):

Chen Shen ◽

David Picketts ◽

Oren Becher

Keyword(s):

Mouse Model ◽

Pediatric Brain Tumor ◽

High Grade Glioma ◽

Genetic Alterations ◽

Genetically Engineered ◽

Tumor Incidence ◽

Loss Of Function ◽

Nestin Expression ◽

Genetically Engineered Mouse Model ◽

Clinical Cases

Abstract Diffuse Intrinsic Potine Glioma (DIPG) is a rare pediatric brain tumor for which no cure or efficacious therapies exist. Previous discoveries have revealed that, DIPG harbors distinct genetic alterations, when compared with adult high-grade glioma (HGG) or even with non-DIPG pediatric HGGs. ATRX alteration is found in 9% of clinical cases of DIPG, and significantly overlaps with H3.3K27M mutation and p53 loss, the two most common genetic changes in DIPG, found in 80% and 77% clinical cases, respectively. Here we developed genetically engineered mouse model of brainstem glioma using the RCAS-Tv-a system by targeting PDGF-B overexpression, p53 loss, H3.3K27M mutation and ATRX loss-of function to Nestin-expression brainstem progenitor cells of the neonatal mouse. Specifically, we used Nestin-Tv-a; p53 floxed; ATRX heterozygous female and Nestin-Tv-a; p53 floxed; ATRX floxed male breeders, generated offsprings with ATRX loss of function (n=18), ATRX heterozygous females (n=6), and ATRX WT (n=10). Median survial of the three groups are 65 days, 88 days and 51 days, respectively. Also, ATRX null mice is lower in tumor incidence (44.4%), compared with ATRX WT (80%). We evaluated the pathological features of DIPG with or without ATRX alteration, RNA-seq is performed to identify differentially expressed genes between ATRX WT and loss-of-function. In conclution, this study generated the first genetically modified mouse model studying ATRX loss-of-function in DIPG, and suggested that ATRX loss-of-function in DIPG may slow down tumorigenesis and decrease tumor incidence.

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LGG-28. NOVEL BRAF INTRAGENIC DELETION IN A GLIOMA: A CASE REPORT OF A PEDIATRIC PATIENT

Neuro-Oncology ◽

10.1093/neuonc/noaa222.410 ◽

2020 ◽

Vol 22 (Supplement_3) ◽

pp. iii371-iii372

Author(s):

Valerie Cruz Flores ◽

Maxine Sutcliffe ◽

Thomas Geller ◽

Ignacio Gonzalez Gomez ◽

Stephanie Smith ◽

...

Keyword(s):

Pediatric Patient ◽

Pilocytic Astrocytoma ◽

Pediatric Population ◽

Binding Pocket ◽

Genetic Alterations ◽

Low Grade ◽

Braf Gene ◽

Intragenic Deletion ◽

Whole Genome Microarray ◽

Intragenic Deletions

Abstract BACKGROUND Numerous variant BRAF genetic alterations have been associated with malignancies. BRAF activating fusions/mutations are frequently present in low grade gliomas. BRAF intragenic deletions have been reported in melanoma, but have not previously been reported in gliomas. OBJECTIVE To report a BRAF intragenic deletion in a pediatric patient with recurrent low-grade glioma. RESULTS A 3-year-old female underwent a complete resection of a posterior fossa pilocytic astrocytoma. She had recurrences at age 4, and then at age 9; pathology was consistent with pilocytic astrocytoma. Microarray analysis on sample from the first recurrence showed one region of loss encompassing 86 Kbp within the BRAF gene. The deletion breakpoints are within intron 1 and 9, resulting in loss of exons 2 through 9, inclusive. This has been previously described melanoma, but appears to be a novel finding in glioma. It is hypothesized that, since the loss retains the kinase and ATP binding pocket domains but deletes the N-terminal conserved region 1 and 2 (CR1, CR2) of the BRAF gene, it is likely functionally similar to the loss and activation resulting from the more usually described KIAA1549 and BRAF gene fusion. CONCLUSION This is the first BRAF intragenic deletion involving exons 2–9 reported in a glioma. Although 86kbp is small using whole genome microarray technology, it is large using sequencing strategies, and a targeted sequencing approach to investigate the BRAF gene would not readily identify this deletion. It is speculated that the deletion may be under ascertained in the pediatric population.

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Genetically engineered birds; pre-CRISPR and CRISPR era

Biology of Reproduction ◽

10.1093/biolre/ioab196 ◽

2021 ◽

Author(s):

Nima Dehdilani ◽

Sara Yousefi Taemeh ◽

Lena Goshayeshi ◽

Hesam Dehghani

Keyword(s):

Genome Engineering ◽

Genetically Engineered ◽

Biopharmaceutical Industry ◽

Avian Genome ◽

Genome Manipulation ◽

Broad Overview

Abstract Generating biopharmaceuticals in genetically engineered bioreactors continues to reign supreme. Hence, genetically engineered birds have attracted considerable attention from the biopharmaceutical industry. Fairly recent genome engineering methods have made genome manipulation an easy and affordable task. In this review, we first provide a broad overview of the approaches and main impediments ahead of generating efficient and reliable genetically engineered birds, and various factors that affect the fate of a transgene. This section provides an essential background for the rest of the review, in which we discuss and compare different genome manipulation methods in the pre-CRISPR and CRISPR era in the field of avian genome engineering.

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Preclinical Models Provide Scientific Justification and Translational Relevance for Moving Novel Therapeutics into Clinical Trials for Pediatric Cancer

Cancer Research ◽

10.1158/0008-5472.can-15-1308 ◽

2015 ◽

Vol 75 (24) ◽

pp. 5176-5186 ◽

Cited By ~ 9

Author(s):

David M. Langenau ◽

Alejandro Sweet-Cordero ◽

Robert J. Wechsler-Reya ◽

Michael A. Dyer

Keyword(s):

Clinical Trials ◽

Pediatric Cancer ◽

Preclinical Models ◽

Novel Therapeutics ◽

Scientific Justification

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Mutational profiles of ovarian cancer in Chinese patients revealed potential therapeutic targets and prognostic markers.

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.15_suppl.e17525 ◽

2021 ◽

Vol 39 (15_suppl) ◽

pp. e17525-e17525

Author(s):

Weiwei Feng ◽

Tianjiao Lyu ◽

Hua Liu ◽

Yahui Jiang ◽

Lifei Shen ◽

...

Keyword(s):

Ovarian Cancer ◽

Homologous Recombination ◽

Prognostic Markers ◽

Therapeutic Targets ◽

Genetic Alterations ◽

Copy Number Variations ◽

Chinese Patients ◽

Disease Stage ◽

Platinum Sensitivity ◽

Platinum Resistant

e17525 Background: Ovarian cancer (OC) is a common and lethal gynecologic malignancy. The prognosis of OC is variable among different patients treated with standard of care therapies. Herein, we described mutational profiles of OC to identify underlying therapeutic targets and prognostic markers. Methods: The study was performed in 38 Chinese patients with high-grade serous ovarian cancer (HGSC), the most common subtype of OC. Most patients (86.8%) had advanced disease (stage III-IV). Tissue samples were subjected to capture-based targeted sequencing using a panel consisting of 520 cancer related genes. Mutational profiles including gene mutations and copy number variations (CNVs) were evaluated in each patient. Homologous recombination deficiency (HRD) status was also assessed. Analysis of mutational profile with platinum-sensitivity, progression-free survival (PFS) and platinum-free interval (PFI) were performed. Results: Genetic alterations were mainly identified in TP53 (97%), BRCA1 (24%), RB1 (21%), FGF23 (21%), CCND2 (18%), RECQL4 (18%) and NF1 (16%). CNVs were comprehensively distributed in 242 genes with 76% (29/38) of patients harboring at least one CNV. In addition to BRCA1, genetic alterations were also presented in other homologous recombination repair (HRR) genes including CDK12 (5%), BRCA2 (3%), ATM (3%), BRIP1 (3%), CHEK1 (3%) and FANCI (3%). There were 22 of 38 (58%) patients with genetic alterations of the HRR pathway. In the study, 28 patients were platinum-sensitive (74%) and 10 were platinum-resistant (26%). Platinum-sensitivity was significantly associated with BRCA1/2 mutations (p < 0.01). In platinum-resistant patients, 7 of 10 patients harbored genetic alterations of actionable therapeutic targets such as PIK3CA, TSC1 and HER2 alterations. The prognosis analysis indicated that BRCA1/2 mutations were significantly associated with improved PFI (p < 0.05) and marginally associated with improved PFS (p = 0.05). Although no association was observed between HRD status and patient prognosis, subgroup analysis in patients with R0 resection found positive HRD showing significant association with better PFI (p < 0.05) and marginal association with better PFS (p = 0.06). Further analysis of HRD classified by NF1 revealed different PFS and PFI among patients harboring positive HRD, negative HRD with NF1 mutations and negative HRD with wild type NF1 (p < 0.05). The study also observed association of LRP1B mutations and RAD52 amplification with worse PFS (p < 0.05). Conclusions: In OC patients, genetic mutations were frequently occurred in both HRR and non HRR genes. CNVs were widely presented in many genes and patients. The mutational profiling also identified a number of potential therapeutic targets and prognostic markers at molecular level which could contribute to personalized treatment and management of OC.

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Neurotrophic Receptor Tyrosine Kinase 2 (NTRK2) Alterations in Low-Grade Gliomas: Report of a Novel Gene Fusion Partner in a Pilocytic Astrocytoma and Review of the Literature

Case Reports in Pathology ◽

10.1155/2020/5903863 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7

Author(s):

Siobhan S. Pattwell ◽

Eric Q. Konnick ◽

Yajuan J. Liu ◽

Rebecca A. Yoda ◽

Laligam N. Sekhar ◽

...

Keyword(s):

Pilocytic Astrocytoma ◽

Gene Fusion ◽

Pediatric Population ◽

Neurofibromatosis Type ◽

Genetic Alterations ◽

Neurotrophin Receptor ◽

Low Grade ◽

Fusion Partner ◽

Tyrosine Kinase 2 ◽

Cns Neoplasms

Pilocytic astrocytoma is a low-grade glial neoplasm of the central nervous system (CNS) that tends to occur in the pediatric population and less commonly presents in adults. Hereditary pilocytic astrocytoma is often associated with germline genetic alterations in the tumor suppressor NF1, the gene responsible for the syndrome neurofibromatosis type 1. Sporadic pilocytic astrocytoma frequently harbors somatic alterations in BRAF, with rare pilocytic astrocytomas containing alterations in FGFR1 and NTRK2. NTRK2 encodes for the protein tropomyosin receptor kinase B (TrkB), which is a neurotrophin receptor with high affinity for Brain-Derived Neurotrophic Factor (BDNF), and plays a role in several physiological functions of neurons, including cell survival and differentiation. In this report, we describe a novel PML-NTRK2 gene fusion occurring in an adult sporadic pilocytic astrocytoma and review the biology and implications of specific NTRK2 mutations occurring in CNS neoplasms.

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Dissimilar Appearances Are Deceptive–Common microRNAs and Therapeutic Strategies in Liver Cancer and Melanoma

Cells ◽

10.3390/cells9010114 ◽

2020 ◽

Vol 9 (1) ◽

pp. 114

Author(s):

Lisa Linck-Paulus ◽

Claus Hellerbrand ◽

Anja K. Bosserhoff ◽

Peter Dietrich

Keyword(s):

Cancer Progression ◽

Molecular Mechanisms ◽

Current Knowledge ◽

Therapeutic Targets ◽

Genetic Alterations ◽

Therapeutic Strategies ◽

The Future ◽

Associated Proteins ◽

Cancer Types ◽

Novel Therapeutic Strategies

In this review, we summarize the current knowledge on miRNAs as therapeutic targets in two cancer types that were frequently described to be driven by miRNAs—melanoma and hepatocellular carcinoma (HCC). By focusing on common microRNAs and associated pathways in these—at first sight—dissimilar cancer types, we aim at revealing similar molecular mechanisms that are evolved in microRNA-biology to drive cancer progression. Thereby, we also want to outlay potential novel therapeutic strategies. After providing a brief introduction to general miRNA biology and basic information about HCC and melanoma, this review depicts prominent examples of potent oncomiRs and tumor-suppressor miRNAs, which have been proven to drive diverse cancer types including melanoma and HCC. To develop and apply miRNA-based therapeutics for cancer treatment in the future, it is essential to understand how miRNA dysregulation evolves during malignant transformation. Therefore, we highlight important aspects such as genetic alterations, miRNA editing and transcriptional regulation based on concrete examples. Furthermore, we expand our illustration by focusing on miRNA-associated proteins as well as other regulators of miRNAs which could also provide therapeutic targets. Finally, design and delivery strategies of miRNA-associated therapeutic agents as well as potential drawbacks are discussed to address the question of how miRNAs might contribute to cancer therapy in the future.

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Fine-tuning patient-derived xenograft models for precision medicine approaches in leukemia

Journal of Investigative Medicine ◽

10.1136/jim-2016-000076 ◽

2016 ◽

Vol 64 (3) ◽

pp. 740-744 ◽

Cited By ~ 8

Author(s):

Olivia L Francis ◽

Terry-Ann M Milford ◽

Cornelia Beldiman ◽

Kimberly J Payne

Keyword(s):

Precision Medicine ◽

Lymphoblastic Leukemia ◽

Genetic Alterations ◽

Fine Tuning ◽

Leukemia Cells ◽

Human Leukemia ◽

Preclinical Models ◽

Species Activity ◽

Pdx Models

Many leukemias are characterized by well-known mutations that drive oncogenesis. Mice engineered with these mutations provide a foundation for understanding leukemogenesis and identifying therapies. However, data from whole genome studies provide evidence that malignancies are characterized by multiple genetic alterations that vary between patients, as well as inherited genetic variation that can also contribute to oncogenesis. Improved outcomes will require precision medicine approaches–targeted therapies tailored to malignancies in each patient. Preclinical models that reflect the range of mutations and the genetic background present in patient populations are required to develop and test the combinations of therapies that will be used to provide precision medicine therapeutic strategies. Patient-derived xenografts (PDX) produced by transplanting leukemia cells from patients into immune deficient mice provide preclinical models where disease mechanisms and therapeutic efficacy can be studied in vivo in context of the genetic variability present in patient tumors. PDX models are possible because many elements in the bone marrow microenvironment show cross-species activity between mice and humans. However, several cytokines likely to impact leukemia cells are species-specific with limited activity on transplanted human leukemia cells. In this review we discuss the importance of PDX models for developing precision medicine approaches to leukemia treatment. We illustrate how PDX models can be optimized to overcome a lack of cross-species cytokine activity by reviewing a recent strategy developed for use with a high-risk form of B-cell acute lymphoblastic leukemia (B-ALL) that is characterized by overexpression of CRLF2, a receptor component for the cytokine, TSLP.

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