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Molecular Heterogeneity in BRAF-Mutant Gliomas: Diagnostic, Prognostic, and Therapeutic Implications. Cancers (Basel) 2023; 15:cancers15041268. [PMID: 36831610 PMCID: PMC9954401 DOI: 10.3390/cancers15041268] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 01/25/2023] [Accepted: 02/04/2023] [Indexed: 02/19/2023] Open
Abstract
Over the last few decades, deciphering the alteration of molecular pathways in brain tumors has led to impressive changes in diagnostic refinement. Among the molecular abnormalities triggering and/or driving gliomas, alterations in the MAPK pathway reign supreme in the pediatric population, as it is encountered in almost all low-grade pediatric gliomas. Activating abnormalities in the MAPK pathway are also present in both pediatric and adult high-grade gliomas. Across those alterations, BRAF p.V600E mutations seem to define homogeneous groups of tumors in terms of prognosis. The recent development of small molecules inhibiting this pathway retains the attention of neurooncologists on BRAF-altered tumors, as conventional therapies showed no significant effect, nor prolonged efficiency on the high-grade or low-grade unresectable forms. Nevertheless, tumoral heterogeneity and especially molecular alteration(s) associated with MAPK-pathway abnormalities are not fully understood with respect to how they might lead to the specific dismal prognosis of those gliomas and/or affect their response to targeted therapies. This review is an attempt to provide comprehensive information regarding molecular alterations related to the aggressiveness modulation in BRAF-mutated gliomas and the current knowledge on how to use those targeted therapies in such situations.
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2
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Di Nunno V, Gatto L, Tosoni A, Bartolini S, Franceschi E. Implications of BRAF V600E mutation in gliomas: Molecular considerations, prognostic value and treatment evolution. Front Oncol 2023; 12:1067252. [PMID: 36686797 PMCID: PMC9846085 DOI: 10.3389/fonc.2022.1067252] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 12/12/2022] [Indexed: 01/06/2023] Open
Abstract
Gliomas are molecularly heterogeneous brain tumors responsible for the most years of life lost by any cancer. High-grade gliomas have a poor prognosis and despite multimodal treatment including surgery, radiotherapy, and chemotherapy, exhibit a high recurrence rate. There is a need for new therapeutic approaches based on precision medicine informed by biomarker assessment and BRAF, a key regulator of MAPK signaling pathway, influencing cell differentiation, proliferation, migration and pro-tumorigenic activity, is emerging as a promising molecular target. V600E, is the most frequent BRAF alteration in gliomas, especially in pediatric low-grade astrocytomas, pleomorphic xanthoastrocytoma, papillary craniopharyngioma, epithelioid glioblastoma and ganglioglioma. The possible application of BRAF-targeted therapy in gliomas is continuously growing and there is preliminary evidence of prolonged disease control obtained by BRAF inhibitors in tumors harboring BRAF V600E mutation. The possibility of introducing targeted therapies into the treatment algorithm represents a paradigm shift for patients with BRAF V600E mutant recurrent high-grade and low-grade glioma and BRAF routine testing should be considered in clinical practice. The focus of this review is to summarize the molecular landscape of BRAF across glioma subtypes and the novel therapeutic strategies for BRAF V600E mutated tumors.
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Affiliation(s)
| | - Lidia Gatto
- Department of Oncology, AUSL Bologna, Bologna, Italy,*Correspondence: Lidia Gatto,
| | - Alicia Tosoni
- Nervous System Medical Oncology Department, IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Stefania Bartolini
- Nervous System Medical Oncology Department, IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Enrico Franceschi
- Nervous System Medical Oncology Department, IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
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3
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Marlow C, Cuoco JA, Hoggarth AR, Stump MS, Apfel LS, Rogers CM. Pediatric diffuse hemispheric glioma H3 G34-mutant with gains of the BRAF locus: An illustrative case. Rare Tumors 2023; 15:20363613231168704. [PMID: 37056711 PMCID: PMC10088409 DOI: 10.1177/20363613231168704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 03/22/2023] [Indexed: 04/15/2023] Open
Abstract
Diffuse hemispheric glioma, H3 G34-mutant, is a recently recognized distinct high-grade glioma with a dismal prognosis. In addition to the H3 G34 missense mutation, numerous genetic events have been identified in these malignant tumors, including ATRX, TP53, and, rarely, BRAF genes. There are only a few reports to date that have identified BRAF mutations in diffuse hemispheric glioma, H3 G34-mutant. Moreover, to our knowledge, gains of the BRAF locus have yet to be described. Here, we present a case of an 11-year-old male with a diffuse hemispheric glioma, H3 G34-mutant, found to have novel gains of the BRAF locus. Furthermore, we emphasize the current genetic landscape of diffuse hemispheric glioma, H3 G34-mutant, and implications of an aberrant BRAF signaling pathway.
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Affiliation(s)
| | - Joshua A Cuoco
- Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
- Section of Neurosurgery, Carilion Clinic, Roanoke, VA, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
- Joshua A Cuoco, Carilion Clinic, Section of Neurosurgery, 2331 Franklin Road, Roanoke 24014, VA, USA.
| | - Austin R Hoggarth
- Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
- Section of Neurosurgery, Carilion Clinic, Roanoke, VA, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Michael S Stump
- Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
- Department of Pathology, Carilion Clinic, Roanoke, VA, USA
| | - Lisa S Apfel
- Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
- Section of Neurosurgery, Carilion Clinic, Roanoke, VA, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Cara M Rogers
- Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
- Section of Neurosurgery, Carilion Clinic, Roanoke, VA, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
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4
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Chludzinski E, Puff C, Weber J, Hewicker-Trautwein M. Case Report: Primary Diffuse Leptomeningeal Oligodendrogliomatosis in a Young Adult Cat. Front Vet Sci 2021; 8:795126. [PMID: 34977226 PMCID: PMC8714914 DOI: 10.3389/fvets.2021.795126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 11/22/2021] [Indexed: 11/14/2022] Open
Abstract
A 2-year-old cat was presented with progressive ataxia. Despite treatment the animal died. Pathomorphological examination revealed a widespread leptomeningeal mass at all levels of the central nervous system accentuated on the cervical spinal cord and the medulla oblongata without presence of a primary intraaxial tumor. The neoplasm was mainly composed of round, uninucleate cells with hyperchromatic nuclei, which were immunopositive for OLIG2, doublecortin, MAP2, synaptophysin, and vimentin, indicating components of both oligodendroglial and neuronal differentiation. Ki-67 immunohistochemistry indicated a high proliferation activity of the neoplasm. Few GFAP positive and Iba-1 positive cells were interpreted as reactive astrocytes and macrophages or microglia, respectively. The tumor was immunonegative for CD3, CD20, PAX5, MUM1, pan-cytokeratin, S100, NSE, p75NTR, NeuN and periaxin. These findings led to the diagnosis of primary diffuse leptomeningeal oligodendrogliomatosis. This is the first reported case of this entity in a young cat, which should be considered as a differential diagnosis for diffuse subarachnoidal round cell infiltrates.
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Affiliation(s)
- Elisa Chludzinski
- Department of Pathology, University of Veterinary Medicine, Hannover, Germany
| | - Christina Puff
- Department of Pathology, University of Veterinary Medicine, Hannover, Germany
| | - Jürgen Weber
- Tierärztliche Praxis für Kleintiere Dr. med. vet. Jürgen Weber, Oer-Erkenschwick, Germany
| | - Marion Hewicker-Trautwein
- Department of Pathology, University of Veterinary Medicine, Hannover, Germany
- *Correspondence: Marion Hewicker-Trautwein
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5
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Kong BY, Sim HW, Nowak AK, Yip S, Barnes EH, Day BW, Buckland ME, Verhaak R, Johns T, Robinson C, Thomas MA, Giardina T, Lwin Z, Scott AM, Parkinson J, Jeffree R, Lourenco RDA, Hovey EJ, Cher LM, Kichendasse G, Khasraw M, Hall M, Tu E, Amanuel B, Koh ES, Gan HK. LUMOS - Low and Intermediate Grade Glioma Umbrella Study of Molecular Guided TherapieS at relapse: Protocol for a pilot study. BMJ Open 2021; 11:e054075. [PMID: 37185327 PMCID: PMC8719186 DOI: 10.1136/bmjopen-2021-054075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Introduction Grades 2 and 3 gliomas (G2/3 gliomas), when combined, are the second largest group of malignant brain tumours in adults. The outcomes for G2/3 gliomas at progression approach the dismal outcomes for glioblastoma (GBM), yet there is a paucity of trials for Australian patients with relapsed G2/3 gliomas compared with patients with GBM. LUMOS will be a pilot umbrella study for patients with relapsed G2/3 gliomas that aims to match patients to targeted therapies based on molecular screening with contemporaneous tumour tissue. Participants in whom no actionable or no druggable mutation is found, or in whom the matching drug is not available, will form a comparator arm and receive standard of care chemotherapy. The objective of the LUMOS trial is to assess the feasibility of this approach in a multicentre study across five sites in Australia, with a view to establishing a national molecular screening platform for patient treatment guided by the mutational analysis of contemporaneous tissue biopsies Methods and analysis This study will be a multicentre pilot study enrolling patients with recurrent grade 2/3 gliomas that have previously been treated with radiotherapy and chemotherapy at diagnosis or at first relapse. Contemporaneous tumour tissue at the time of first relapse, defined as tissue obtained within 6 months of relapse and without subsequent intervening therapy, will be obtained from patients. Molecular screening will be performed by targeted next-generation sequencing at the reference laboratory (PathWest, Perth, Australia). RNA and DNA will be extracted from representative formalin-fixed paraffin embedded tissue scrolls or microdissected from sections on glass slides tissue sections following a review of the histology by pathologists. Extracted nucleic acid will be quantified by Qubit Fluorometric Quantitation (Thermo Fisher Scientific). Library preparation and targeted capture will be performed using the TruSight Tumor 170 (TST170) kit and samples sequenced on NextSeq 550 (Illumina) using NextSeq V.2.5 hi output reagents, according to the manufacturer’s instructions. Data analysis will be performed using the Illumina BaseSpace TST170 app v1.02 and a custom tertiary pipeline, implemented within the Clinical Genomics Workspace software platform from PierianDx (also refer to section 3.2). Primary outcomes for the study will be the number of patients enrolled and the number of patients who complete molecular screening. Secondary outcomes will include the proportion of screened patients enrolled; proportion of patients who complete molecular screening; the turn-around time of molecular screening; and the value of a brain tumour specific multi-disciplinary tumour board, called the molecular tumour advisory panel as measured by the proportion of patients in whom the treatment recommendation was refined compared with the recommendations from the automated bioinformatics platform of the reference laboratory testing. Ethics and dissemination The study was approved by the lead Human Research Ethics Committee of the Sydney Local Health District: Protocol No. X19-0383. The study will be conducted in accordance with the principles of the Declaration of Helsinki 2013, guidelines for Good Clinical Practice and the National Health and Medical Research Council National Statement on Ethical Conduct in Human Research (2007, updated 2018 and as amended periodically). Results will be disseminated using a range of media channels including newsletters, social media, scientific conferences and peer-reviewed publications. Trial registration number ACTRN12620000087954; Pre-results.
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Affiliation(s)
- Benjamin Y Kong
- NHMRC Clinical Trials Centre, Camperdown, New South Wales, Australia
- Department of Medical Oncology, Royal North Shore Hospital, St Leonards, New South Wales, Australia
| | - Hao-Wen Sim
- NHMRC Clinical Trials Centre, Camperdown, New South Wales, Australia
- Department of Medical Oncology, Chris O'Brien Lifehouse, Camperdown, New South Wales, Australia
- Kinghorn Cancer Centre, St Vincent's Hospital Sydney, Darlinghurst, New South Wales, Australia
- St Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales, Australia
| | - Anna K Nowak
- Department of Medical Oncology, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
- Medical School, The University of Western Australia, Perth, Western Australia, Australia
| | - Sonia Yip
- NHMRC Clinical Trials Centre, Camperdown, New South Wales, Australia
| | | | - Bryan W Day
- School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
- Sid Faithfull Brain Cancer Laboratory, Cell and Molecular Biology Department, QIMR Berghofer, Herston, Queensland, Australia
| | - Michael E Buckland
- Department of Neuropathology, Brain and Mind Centre, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia
| | - Roel Verhaak
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut, USA
| | - Terrance Johns
- Oncogenic Signalling Laboratory, Telethon Kids Institute, Nedlands, Western Australia, Australia
| | - Cleo Robinson
- Department of Anatomical Pathology, PathWest Laboratory Medicine, Nedlands, Western Australia, Australia
| | - Marc A Thomas
- Department of Anatomical Pathology, PathWest Laboratory Medicine, Nedlands, Western Australia, Australia
| | - Tindaro Giardina
- Department of Anatomical Pathology, PathWest Laboratory Medicine, Nedlands, Western Australia, Australia
| | - Zarnie Lwin
- Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia
- Cancer Care Services, Royal Brisbane and Women's Hospital, Herston, Queensland, Australia
| | - Andrew M Scott
- Department of Molecular Imaging and Therapy, Austin Health, Heidelberg, Victoria, Australia
- Olivia Newton-John Cancer Research Institute, Heidelberg, Victoria, Australia
- Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
- School of Cancer Medicine, La Trobe University, Melbourne, Victoria, Australia
| | - Jonathon Parkinson
- Department of Neurosurgery, Royal North Shore Hospital, St Leonards, New South Wales, Australia
| | - Rosalind Jeffree
- Department of Neurosurgery, Royal Brisbane and Women's Hospital, Herston, Queensland, Australia
- University of Queensland School of Medicine, Herston, Queensland, Australia
| | - Richard de Abreu Lourenco
- Centre for Health Economics Research and Evaluation, University of Technology, Ultimo, New South Wales, Australia
| | - Elizabeth J Hovey
- Department of Medical Oncology, Nelune Comprehensive Cancer Centre, Prince of Wales Hospital, Randwick, New South Wales, Australia
- Faculty of Medicine, University of New South Wales, Randwick, New South Wales, Australia
| | - Lawrence M Cher
- Department of Neurology, Austin Health, Heidelberg, Victoria, Australia
| | - Ganessan Kichendasse
- Department of Clinical Pharmacology, College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
- Department of Medical Oncology, Flinders Centre for Innovation in Cancer, Bedford Park, South Australia, Australia
| | - Mustafa Khasraw
- Preston Robert Tisch Brain Tumor Center at Duke, Department of Neurosurgery, Duke University Medical Center, Durham, North Carolina, USA
| | - Merryn Hall
- NHMRC Clinical Trials Centre, Camperdown, New South Wales, Australia
| | - Emily Tu
- NHMRC Clinical Trials Centre, Camperdown, New South Wales, Australia
| | - Benhur Amanuel
- Department of Anatomical Pathology, PathWest Laboratory Medicine, Nedlands, Western Australia, Australia
| | - Eng-Siew Koh
- Faculty of Medicine, University of New South Wales, Randwick, New South Wales, Australia
- Department of Radiation Oncology, Liverpool Cancer Therapy Centre, Liverpool, New South Wales, Australia
- Collaboration for Cancer Outcomes, Research and Evaluation, Ingham Institute for Applied Medical Research, Liverpool, New South Wales, Australia
| | - Hui K Gan
- Olivia Newton-John Cancer Research Institute, Heidelberg, Victoria, Australia
- Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
- School of Cancer Medicine, La Trobe University, Melbourne, Victoria, Australia
- Department of Medical Oncology, Olivia Newton-John Cancer Centre at Austin Health, Heidelberg, Victoria, Australia
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Srinivasa K, Cross KA, Dahiya S. BRAF Alteration in Central and Peripheral Nervous System Tumors. Front Oncol 2020; 10:574974. [PMID: 33042847 PMCID: PMC7523461 DOI: 10.3389/fonc.2020.574974] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/20/2020] [Indexed: 12/12/2022] Open
Abstract
BRAF (alternately referred to as v-raf murine sarcoma viral oncogene homolog B1) is a proto-oncogene involved in the mitogen-activated protein kinase (MAPK) pathway. BRAF alterations are most commonly missense mutations or aberrant fusions. These mutations are observed in numerous primary central nervous system tumors as well as metastases. This review discusses the prevalence of BRAF alteration within select notable CNS tumors, and their prognostic associations. Included are some novel entities such as diffuse leptomeningeal glioneuronal tumor (DLGNT), polymorphous low grade neuroepithelial tumor of the young (PLNTY), and multinodular and vacuolating neuronal tumor (MVNT). Knowledge of this gene’s integrity in CNS and PNS tumors can have profound diagnostic and therapeutic implications. Also reviewed are the current state of targeted therapy against aberrant BRAF as it pertains mostly to the CNS and to a lesser extent in PNS, and certain diagnostic aspects.
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Affiliation(s)
- Komal Srinivasa
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, United States
| | - Kevin A Cross
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, MO, United States
| | - Sonika Dahiya
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, United States
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7
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Oncogenic BRAF Alterations and Their Role in Brain Tumors. Cancers (Basel) 2019; 11:cancers11060794. [PMID: 31181803 PMCID: PMC6627484 DOI: 10.3390/cancers11060794] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 06/05/2019] [Accepted: 06/06/2019] [Indexed: 12/26/2022] Open
Abstract
Alterations of the v-raf murine sarcoma viral oncogene homolog B (BRAF) have been extensively studied in several tumor entities and are known to drive cell growth in several tumor entities. Effective targeted therapies with mutation-specific small molecule inhibitors have been developed and established for metastasized malignant melanoma. The BRAF V600E mutation and KIAA1549-BRAF fusion are alterations found in several brain tumors and show a distinct prognostic impact in some entities. Besides the diagnostic significance for the classification of central nervous system tumors, these alterations present possible therapy targets that may be exploitable for oncological treatments, as it has been established for malignant melanomas. In this review the different central nervous system tumors harboring BRAF alterations are presented and the diagnostic significance, prognostic role, and therapeutic potential are discussed.
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8
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Risk assessment in paediatric glioma—Time to move on from the binary classification. Crit Rev Oncol Hematol 2017; 111:52-59. [DOI: 10.1016/j.critrevonc.2017.01.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 11/28/2016] [Accepted: 01/18/2017] [Indexed: 11/24/2022] Open
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9
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Pathak P, Kumar A, Jha P, Purkait S, Faruq M, Suri A, Suri V, Sharma MC, Sarkar C. Genetic alterations related to BRAF-FGFR genes and dysregulated MAPK/ERK/mTOR signaling in adult pilocytic astrocytoma. Brain Pathol 2017; 27:580-589. [PMID: 27608415 DOI: 10.1111/bpa.12444] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 09/05/2016] [Indexed: 01/05/2023] Open
Abstract
Pilocytic astrocytomas occur rarely in adults and show aggressive tumor behavior. However, their underlying molecular-genetic events are largely uncharacterized. Hence, 59 adult pilocytic astrocytoma (APA) cases of classical histology were studied (MIB-1 LI: 1%-5%). Analysis of BRAF alterations using qRT-PCR, confirmed KIAA1549-BRAF fusion in 11 (19%) and BRAF-gain in 2 (3.4%) cases. BRAF-V600E mutation was noted in 1 (1.7%) case by sequencing. FGFR1-mutation and FGFR-TKD duplication were seen in 7/59 (11.9%) and 3/59 (5%) cases, respectively. Overall 36% of APAs harbored BRAF and/or FGFR genetic alterations. Notably, FGFR related genetic alterations were enriched in tumors of supratentorial region (8/25, 32%) as compared with other locations (P = 0.01). The difference in age of cases with FGFR1-mutation (Mean age ± SD: 37.2 ± 15 years) vs. KIAA1549-BRAF fusion (Mean age ± SD: 25.1 ± 4.1 years) was statistically significant (P = 0.03). Combined BRAF and FGFR alterations were identified in 3 (5%) cases. Notably, the cases with more than one genetic alteration were in higher age group (Mean age ± SD: 50 ± 12 years) as compared with cases with single genetic alteration (Mean age ± SD: 29 ± 10; P = 0.003). Immunopositivity of p-MAPK/p-MEK1 was found in all the cases examined. The pS6-immunoreactivity, a marker of mTOR activation was observed in 34/39 (87%) cases. Interestingly, cases with BRAF and/or FGFR related alteration showed significantly lower pS6-immunostatining (3/12; 25%) as compared with those with wild-type BRAF and/or FGFR (16/27; 59%) (P = 0.04). Further, analysis of seven IDH wild-type adult diffuse astrocytomas (DA) showed FGFR related genetic alterations in 43% cases. These and previous results suggest that APAs are genetically similar to IDH wild-type adult DAs. APAs harbor infrequent BRAF alterations but more frequent FGFR alterations as compared with pediatric cases. KIAA1549-BRAF fusion inversely correlates with increasing age whereas FGFR1-mutation associates with older age. Activation of MAPK/ERK/mTOR signaling appears to be an important oncogenic event in APAs and may be underlying event of aggressive tumor behavior. The findings provided a rationale for potential therapeutic advantage of targeting MAPK/ERK/mTOR pathway in APAs.
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Affiliation(s)
- Pankaj Pathak
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Anupam Kumar
- Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India
| | - Prerana Jha
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Suvendu Purkait
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Mohammed Faruq
- Genomics and Molecular Medicine, Council of Scientific and Industrial Research - Institute of Genomics and Integrative Biology (CSIR- IGIB), New Delhi, India
| | - Ashish Suri
- Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India
| | - Vaishali Suri
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Mehar C Sharma
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Chitra Sarkar
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
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Filbin MG, Suvà ML. Gliomas Genomics and Epigenomics: Arriving at the Start and Knowing It for the First Time. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2016; 11:497-521. [DOI: 10.1146/annurev-pathol-012615-044208] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Mariella G. Filbin
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114;
- Center for Cancer Research, Massachusetts General Hospital, Boston, Massachusetts 02114;
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142
- Cancer and Blood Disorders Center, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, Massachusetts 02215
| | - Mario L. Suvà
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114;
- Center for Cancer Research, Massachusetts General Hospital, Boston, Massachusetts 02114;
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142
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11
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Dodgshun AJ, SantaCruz N, Hwang J, Ramkissoon SH, Malkin H, Bergthold G, Manley P, Chi S, MacGregor D, Goumnerova L, Sullivan M, Ligon K, Beroukhim R, Herrington B, Kieran MW, Hansford JR, Bandopadhayay P. Disseminated glioneuronal tumors occurring in childhood: treatment outcomes and BRAF alterations including V600E mutation. J Neurooncol 2016; 128:293-302. [PMID: 26994902 DOI: 10.1007/s11060-016-2109-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 03/10/2016] [Indexed: 12/21/2022]
Abstract
Disseminated glioneuronal tumors of childhood are rare. We present a retrospective IRB-approved review of the clinical course and frequency of BRAF mutations in disseminated glioneuronal tumors at two institutions. Defining features of our cohort include diffuse leptomeningeal-spread, often with a discrete spinal cord nodule and oligodendroglioma-like histologic features. Patients were identified through a pathology database search of all cases with disseminated low-grade neoplasms with an oligodendroglioma-like component. De-identified clinical information was collected by chart review and all imaging was reviewed. We retrieved the results of targeted genomic analyses for alterations in BRAF. Ten patients (aged 2-14 years) were identified from the Dana-Farber/Boston Children's Hospital and the Royal Children's Hospital, Melbourne pathology databases. Nine patients received chemotherapy. Eight patients are alive, although three have had episodes of progressive disease. We identified genomic alterations affecting the MAPK pathway in six patients. One patient had a germline RAF1 mutation and a clinical diagnosis of cardio-facio-cutaneous syndrome. BRAF duplications were identified in four and BRAF V600E mutation was identified in one. These data support the presence of targetable genomic alterations in this disease.
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Affiliation(s)
- Andrew J Dodgshun
- Children's Cancer Centre, Royal Children's Hospital, 50 Flemington Road, Parkville, Melbourne, VIC, 3052, Australia.
- Department of Paediatrics, University of Melbourne, Melbourne, VIC, 3052, Australia.
| | - Nadine SantaCruz
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, 450 Longwood Ave, Boston, 02115, USA
- Harvard Medical School, Boston, MA, USA
| | - Jaeho Hwang
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, 450 Longwood Ave, Boston, 02115, USA
- Harvard Medical School, Boston, MA, USA
| | - Shakti H Ramkissoon
- Department of Medical Oncology, Dana-Faber Cancer Institute, Boston, 02115, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
- Department of Pathology, Boston Children's Hospital, Boston, MA, USA
| | - Hayley Malkin
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, 450 Longwood Ave, Boston, 02115, USA
- Harvard Medical School, Boston, MA, USA
| | - Guillaume Bergthold
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, 450 Longwood Ave, Boston, 02115, USA
- Harvard Medical School, Boston, MA, USA
| | - Peter Manley
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, 450 Longwood Ave, Boston, 02115, USA
- Harvard Medical School, Boston, MA, USA
| | - Susan Chi
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, 450 Longwood Ave, Boston, 02115, USA
- Harvard Medical School, Boston, MA, USA
| | - Duncan MacGregor
- Department of Pathology, Royal Children's Hospital, Melbourne, VIC, 3052, Australia
| | - Liliana Goumnerova
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, 450 Longwood Ave, Boston, 02115, USA
- Harvard Medical School, Boston, MA, USA
- Department of Neurosurgery, Boston Children's Hospital, Boston, MA, USA
- Department of Neurosurgery, Harvard Medical School, Boston, MA, USA
| | - Michael Sullivan
- Children's Cancer Centre, Royal Children's Hospital, 50 Flemington Road, Parkville, Melbourne, VIC, 3052, Australia
- Murdoch Children's Research Institute, Melbourne, VIC, 3052, Australia
| | - Keith Ligon
- Department of Medical Oncology, Dana-Faber Cancer Institute, Boston, 02115, USA
- Broad Institute of MIT and Harvard, Cambridge, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
- Department of Pathology, Boston Children's Hospital, Boston, MA, USA
- Department of Pathology, Harvard Medical School, Boston, MA, USA
| | - Rameen Beroukhim
- Harvard Medical School, Boston, MA, USA
- Department of Medical Oncology, Dana-Faber Cancer Institute, Boston, 02115, USA
- Broad Institute of MIT and Harvard, Cambridge, USA
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Betty Herrington
- Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS, USA
| | - Mark W Kieran
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, 450 Longwood Ave, Boston, 02115, USA
- Harvard Medical School, Boston, MA, USA
| | - Jordan R Hansford
- Children's Cancer Centre, Royal Children's Hospital, 50 Flemington Road, Parkville, Melbourne, VIC, 3052, Australia
- Murdoch Children's Research Institute, Melbourne, VIC, 3052, Australia
| | - Pratiti Bandopadhayay
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, 450 Longwood Ave, Boston, 02115, USA.
- Harvard Medical School, Boston, MA, USA.
- Broad Institute of MIT and Harvard, Cambridge, USA.
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.
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12
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Suzuki Y, Takahashi-Fujigasaki J, Akasaki Y, Matsushima S, Mori R, Karagiozov K, Joki T, Ikeuchi S, Ikegami M, Manome Y, Murayama Y. BRAF V600E-mutated diffuse glioma in an adult patient: a case report and review. Brain Tumor Pathol 2015; 33:40-9. [PMID: 26445861 DOI: 10.1007/s10014-015-0234-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 09/24/2015] [Indexed: 11/30/2022]
Abstract
Recent advances in genomic technology and genome-wide analysis have identified key molecular alterations that are relevant to the diagnosis and prognosis of brain tumors. Molecular information such as mutations in isocitrate dehydrogenase (IDH) genes or 1p/19q co-deletion status will be more actively incorporated into the histological classification of diffuse gliomas. BRAF V600E mutations are found frequently in circumscribed low-grade gliomas such as pleomorphic xanthoastrocytoma (PXA) and extra-cerebellar pilocytic astrocytoma, or epithelioid glioblastomas (E-GBM), a rare variant of GBM. This mutation is relatively rare in other types of diffuse gliomas, especially in adult onset cases. Here, we present an adult onset case of IDH wild-type/BRAF V600E-mutated diffuse glioma, evolving from grade III to grade IV. The tumor displayed atypical exophytic growth and had unusual histological features not fully compatible with, but indicative of PXA and E-GBM. We discuss differential diagnosis of the tumor, and review previously described diffuse gliomas with the BRAF V600E mutation.
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Affiliation(s)
- Yuta Suzuki
- Department of Neurosurgery, The Jikei University School of Medicine, Tokyo, Japan
| | - Junko Takahashi-Fujigasaki
- Department of Neuropathology, Brain Bank for Aging Research, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan.
| | - Yasuharu Akasaki
- Department of Neurosurgery, The Jikei University School of Medicine, Tokyo, Japan
| | - Satoshi Matsushima
- Department of Radiology, The Jikei University School of Medicine, Tokyo, Japan
| | - Ryosuke Mori
- Department of Neurosurgery, The Jikei University School of Medicine, Tokyo, Japan
| | - Kostadin Karagiozov
- Department of Neurosurgery, The Jikei University School of Medicine, Tokyo, Japan
| | - Tatsuhiro Joki
- Department of Neurosurgery, The Jikei University School of Medicine, Tokyo, Japan
| | - Satoshi Ikeuchi
- Department of Neurosurgery, The Jikei University School of Medicine, Tokyo, Japan
| | - Masahiro Ikegami
- Department of Pathology, The Jikei University School of Medicine, Tokyo, Japan
| | - Yoshinobu Manome
- Division of Molecular Cell Biology, Core Research Facilities for Basic Science, The Jikei University School of Medicine, Tokyo, Japan
| | - Yuichi Murayama
- Department of Neurosurgery, The Jikei University School of Medicine, Tokyo, Japan
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13
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Analysis of IDH1-R132 mutation, BRAF V600 mutation and KIAA1549-BRAF fusion transcript status in central nervous system tumors supports pediatric tumor classification. J Cancer Res Clin Oncol 2015; 142:89-100. [PMID: 26115961 DOI: 10.1007/s00432-015-2006-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 06/15/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Gliomas are the leading cause of cancer-related morbidity in children and comprise a clinical, histological and molecular heterogenous group of CNS tumors. Appropriate treatment of these tumors relies on correct classification into tumor types and malignancy grades. METHODS We examined 170 (0-18 years) pediatric and 131 (19-35 years) young adult brain tumors including pilocytic astrocytomas (PAs), pilomyxoid astrocytomas (PMAs), diffuse astrocytomas (DAs), gangliogliomas, dysembryoplastic neuroepithelial tumors (DNTs) and pleomorphic xanthoastrocytomas (PXAs) for IDH1 and BRAF mutation/BRAF fusion gene status. The obtained data were compared to results in 464 (<35 years) adult brain tumors. In 32 tumors with an oligodendroglial or mixed glioma differentiation, additionally the LOH1p/19q status was determined. RESULTS By combining immunohistochemistry and molecular methods, IDH1/2 mutations were observed in 6 pediatric, 35 young adult and 43 adult tumors of the astrocytic/oligodendroglial lineage. BRAF V600E mutations (20 pediatric, 7 young adults and 2 adults) were found mostly in gangliogliomas, PXAs, few astrocytomas and few DNTs. Except for one DA case, BRAF fusions (35 pediatric, 8 young adults and 2 adults) were restricted to PA and PMA and associated with age and infratentorial location. All mutations were mutually exclusive and always present in the primary tumor. Two-thirds of all pediatric samples harbored one of the three examined mutations. CONCLUSION Combination of IDH1-R132, BRAF V600 and KIAA1549-BRAF fusion analysis is therefore a useful tool to increase diagnostic accuracy in pediatric gliomas.
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14
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Brandner S, von Deimling A. Diagnostic, prognostic and predictive relevance of molecular markers in gliomas. Neuropathol Appl Neurobiol 2015; 41:694-720. [PMID: 25944653 DOI: 10.1111/nan.12246] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 04/15/2015] [Indexed: 12/18/2022]
Abstract
The advances of genome-wide 'discovery platforms' and the increasing affordability of the analysis of significant sample sizes have led to the identification of novel mutations in brain tumours that became diagnostically and prognostically relevant. The development of mutation-specific antibodies has facilitated the introduction of these convenient biomarkers into most neuropathology laboratories and has changed our approach to brain tumour diagnostics. However, tissue diagnosis will remain an essential first step for the correct stratification for subsequent molecular tests, and the combined interpretation of the molecular and tissue diagnosis ideally remains with the neuropathologist. This overview will help our understanding of the pathobiology of common intrinsic brain tumours in adults and help guiding which molecular tests can supplement and refine the tissue diagnosis of the most common adult intrinsic brain tumours. This article will discuss the relevance of 1p/19q codeletions, IDH1/2 mutations, BRAF V600E and BRAF fusion mutations, more recently discovered mutations in ATRX, H3F3A, TERT, CIC and FUBP1, for diagnosis, prognostication and predictive testing. In a tumour-specific topic, the role of mitogen-activated protein kinase pathway mutations in the pathogenesis of pilocytic astrocytomas will be covered.
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Affiliation(s)
- Sebastian Brandner
- Division of Neuropathology, The National Hospital for Neurology and Neurosurgery, University College London NHS Foundation Trust, London, UK.,Department of Neurodegeneration, UCL Institute of Neurology, London, UK
| | - Andreas von Deimling
- Department of Neuropathology, University of Heidelberg, Heidelberg, Germany.,Clinical Cooperation Unit Neuropathology, German Cancer Research Center, DKFZ and DKTK, Heidelberg, Germany
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15
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Antonelli M, Badiali M, Moi L, Buttarelli FR, Baldi C, Massimino M, Sanson M, Giangaspero F. KIAA1549:BRAF fusion gene in pediatric brain tumors of various histogenesis. Pediatr Blood Cancer 2015; 62:724-7. [PMID: 25382612 DOI: 10.1002/pbc.25272] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 08/18/2014] [Indexed: 02/01/2023]
Abstract
The KIAA1549:BRAF fusion gene is considered a driver genetic event in pilocytic astrocytoma. We investigated a series of 69 pediatric brain neoplasms of diverse histogenesis and grade using the RT-PCR and sequencing. We detected the KIAA1549:BRAF fusion gene in five of 34 non-PA tumors (14.7%), that is, one glioblastoma, one anaplastic astrocytoma, one anaplastic pleomorphic xanthoastrocytoma, 1 ependymoma, and 1 Atypical Teratoid Rhabdoid Tumor. Our study showed that the K-B, although uncommon, it can be detected in non-PA tumors of various histogenesis and grading.
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Affiliation(s)
- Manila Antonelli
- Department of Radiological, Oncological and Anatomo-Pathological Sciences, Sapienza University, Rome, Italy
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16
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Rodriguez FJ, Schniederjan MJ, Nicolaides T, Tihan T, Burger PC, Perry A. High rate of concurrent BRAF-KIAA1549 gene fusion and 1p deletion in disseminated oligodendroglioma-like leptomeningeal neoplasms (DOLN). Acta Neuropathol 2015; 129:609-610. [PMID: 25720745 DOI: 10.1007/s00401-015-1400-9] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 02/16/2015] [Accepted: 02/17/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Fausto J Rodriguez
- Division of Neuropathology, Department of Pathology, Johns Hopkins Hospital, Johns Hopkins University, Sheikh Zayed Tower, Room M2101, 1800 Orleans Street, Baltimore, MD 21231, USA
| | - Matthew J Schniederjan
- Department of Pathology and Laboratory Administration, Children's Healthcare of Atlanta, 1001 Johnson Ferry Rd NE, Atlanta, GA 30342, USA; Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Room G170, 1364 Clifton Rd NE, Atlanta, GA 30322, USA
| | - Theo Nicolaides
- Department of Pediatrics, University of California San Francisco School of Medicine, 550 16th Street, San Francisco, CA 94143, USA
| | - Tarik Tihan
- Division of Neuropathology, Department of Pathology, University of California San Francisco School of Medicine, 505 Parnassus Avenue, San Francisco, CA 94143, USA
| | - Peter C Burger
- Division of Neuropathology, Department of Pathology, Johns Hopkins Hospital, Johns Hopkins University, Sheikh Zayed Tower, Room M2101, 1800 Orleans Street, Baltimore, MD 21231, USA
| | - Arie Perry
- Division of Neuropathology, Department of Pathology, University of California San Francisco School of Medicine, 505 Parnassus Avenue, San Francisco, CA 94143, USA
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Oncogenic KIAA1549-BRAF fusion with activation of the MAPK/ERK pathway in pediatric oligodendrogliomas. Cancer Genet 2015; 208:91-5. [PMID: 25794445 DOI: 10.1016/j.cancergen.2015.01.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/18/2015] [Accepted: 01/20/2015] [Indexed: 01/01/2023]
Abstract
Pediatric oligodendrogliomas (pODGs) are rare central nervous system tumors, and comparatively little is known about their molecular pathogenesis. Co-deletion of 1p/19q; and IDH1, CIC, and FUBP1 mutations, which are molecular signatures of adult oligodendrogliomas, are extremely rare in pODGs. In this report, two pODGs, one each of grade II and grade III, were evaluated using clinical, radiological, histopathologic, and follow-up methods. IDH1, TP53, CIC, H3F3A, and BRAF-V600 E mutations were analyzed by Sanger sequencing and immunohistochemical methods, and 1p/19q co-deletion was analyzed by fluorescence in situ hybridization. PDGFRA amplification, BRAF gain, intragenic duplication of FGFR-TKD, and KIAA1549-BRAF fusion (validated by Sanger sequencing) were analyzed by real-time reverse transcription PCR. Notably, both cases showed the oncogenic KIAA1549_Ex15-BRAF_Ex9 fusion transcript. Further, immunohistochemical analysis showed activation of the MAPK/ERK pathway in both of these cases. However, neither 1p/19q co-deletion; IDH1, TP53, CIC, H3F3A, nor BRAF-V600 E mutation; PDGFRA amplification; BRAF gain; nor duplication of FGFR-TKD was identified. Overall, this study highlights that pODGs can harbor the KIAA1549-BRAF fusion with aberrant MAPK/ERK signaling, and there exists an option of targeting these pathways in such patients. These results indicate that pODGs with the KIAA1549-BRAF fusion may represent a subset of this rare tumor that shares molecular and genetic features of pilocytic astrocytomas. These findings will increase our understanding of pODGs and may have clinical implications.
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Abstract
Oligodendroglial tumors are relatively rare, comprising approximately 5% of all glial neoplasms. Oligodendroglial tumor patients have a better prognosis than those with astrocytic neoplasms, and patients with tumors that contain 1p/19q co-deletions or IDH-1 mutations appear to be particularly sensitive to treatment. In the past decade, scientists have made significant progress in the unraveling the molecular events that relate to the pathogenesis of these neoplasms. There is considerable excitement resulting from the recent reports from two large phase III randomized trials (European Organization for Research and Treatment of Cancer [EORTC] 26951 and Radiation Therapy Oncology Group [RTOG] 9402), which disclosed that patients with newly diagnosed 1p/19q co-deleted anaplastic oligodendroglial tumors have a 7+year increase in median overall survival following chemoradiation, as compared to radiation alone. This has stimulated a renewed interest in the development of new therapeutic strategies for treatment and potential cure of oligodendroglial tumors, based on an improved scientific understanding of the molecular events involved in the pathogenesis of these neoplasms. The goal of this document is to summarize the key translational developments and recent clinical therapeutic trial data, with a correlative perspective on current and future directions.
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Affiliation(s)
- Kurt A Jaeckle
- Departments of Neurology and Oncology, Mayo Clinic Florida, Jacksonville, FL.
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19
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Theeler BJ, Ellezam B, Sadighi ZS, Mehta V, Tran MD, Adesina AM, Bruner JM, Puduvalli VK. Adult pilocytic astrocytomas: clinical features and molecular analysis. Neuro Oncol 2014; 16:841-7. [PMID: 24470550 PMCID: PMC4022218 DOI: 10.1093/neuonc/not246] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 11/19/2013] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Adult pilocytic astrocytomas (PAs) are rare and have an aggressive clinical course compared with pediatric patients. Constitutive Ras/RAF/MAPK signaling appears to be an important oncogenic event in sporadic PA. We evaluated clinical data and molecular profiles of adult PAs at our institution. METHODS We identified 127 adult PAs in our institutional database. Cases with available tissue were tested for BRAF-KIAA1549 fusion/duplication (B-K fusion) by fluorescence in situ hybridization and submitted for mutation profiling using the Sequenom mutation profiling panel. Subgroup analyses were performed based on clinical and molecular data. RESULTS The majority of adult PAs are supratentorial. Twenty-two percent of cases had an initial pathologic diagnosis discordant with the diagnosis made at our institution. Recurrence was seen in 42% of cases, and 13% of patients died during follow-up. Adjuvant radiotherapy following surgical resection was associated with a statistically significant decrease in progression-free survival (P = .004). B-K fusion was identified in 20% (9 of 45) of patients but was not associated with outcome. No BRAF V600E mutations (0 of 40 tested) were found. CONCLUSION This was the largest single institution series of adult PA. A significant proportion of adult PAs follow an aggressive clinical course. Our results support a period of observation following biopsy or surgical resection. B-K fusion in adult PA does not influence outcome, and BRAF V600E mutation appears to be a very rare event. Further study of tumor biology and optimal treatment is needed, given a more aggressive clinical behavior.
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Affiliation(s)
| | | | - Zsila S. Sadighi
- Department of Neurology and John P. Murtha Cancer Center, Walter Reed National Military Medical Center, Bethesda, Maryland (B.J.T.); Department of Pathology; CHU Sainte-Justine, Universite de Montreal, Montréal Quebec, Canada (B.E.); Pediatric Medicine, St. Jude Children's Research Hospital, Memphis, Tennessee (Z.S.S.); Department of Pathology, Texas Children's Hospital and Baylor College of Medicine, Houston, Texas (V.M., M.D.T., A.M.A.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (J.M.B.); Department of Neurosurgery, The Ohio State University Arthur G. James Cancer Hospital, Columbus, Ohio (V.K.P.)
| | - Vidya Mehta
- Department of Neurology and John P. Murtha Cancer Center, Walter Reed National Military Medical Center, Bethesda, Maryland (B.J.T.); Department of Pathology; CHU Sainte-Justine, Universite de Montreal, Montréal Quebec, Canada (B.E.); Pediatric Medicine, St. Jude Children's Research Hospital, Memphis, Tennessee (Z.S.S.); Department of Pathology, Texas Children's Hospital and Baylor College of Medicine, Houston, Texas (V.M., M.D.T., A.M.A.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (J.M.B.); Department of Neurosurgery, The Ohio State University Arthur G. James Cancer Hospital, Columbus, Ohio (V.K.P.)
| | - M. Diep Tran
- Department of Neurology and John P. Murtha Cancer Center, Walter Reed National Military Medical Center, Bethesda, Maryland (B.J.T.); Department of Pathology; CHU Sainte-Justine, Universite de Montreal, Montréal Quebec, Canada (B.E.); Pediatric Medicine, St. Jude Children's Research Hospital, Memphis, Tennessee (Z.S.S.); Department of Pathology, Texas Children's Hospital and Baylor College of Medicine, Houston, Texas (V.M., M.D.T., A.M.A.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (J.M.B.); Department of Neurosurgery, The Ohio State University Arthur G. James Cancer Hospital, Columbus, Ohio (V.K.P.)
| | - Adekunle M. Adesina
- Department of Neurology and John P. Murtha Cancer Center, Walter Reed National Military Medical Center, Bethesda, Maryland (B.J.T.); Department of Pathology; CHU Sainte-Justine, Universite de Montreal, Montréal Quebec, Canada (B.E.); Pediatric Medicine, St. Jude Children's Research Hospital, Memphis, Tennessee (Z.S.S.); Department of Pathology, Texas Children's Hospital and Baylor College of Medicine, Houston, Texas (V.M., M.D.T., A.M.A.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (J.M.B.); Department of Neurosurgery, The Ohio State University Arthur G. James Cancer Hospital, Columbus, Ohio (V.K.P.)
| | - Janet M. Bruner
- Department of Neurology and John P. Murtha Cancer Center, Walter Reed National Military Medical Center, Bethesda, Maryland (B.J.T.); Department of Pathology; CHU Sainte-Justine, Universite de Montreal, Montréal Quebec, Canada (B.E.); Pediatric Medicine, St. Jude Children's Research Hospital, Memphis, Tennessee (Z.S.S.); Department of Pathology, Texas Children's Hospital and Baylor College of Medicine, Houston, Texas (V.M., M.D.T., A.M.A.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (J.M.B.); Department of Neurosurgery, The Ohio State University Arthur G. James Cancer Hospital, Columbus, Ohio (V.K.P.)
| | - Vinay K. Puduvalli
- Department of Neurology and John P. Murtha Cancer Center, Walter Reed National Military Medical Center, Bethesda, Maryland (B.J.T.); Department of Pathology; CHU Sainte-Justine, Universite de Montreal, Montréal Quebec, Canada (B.E.); Pediatric Medicine, St. Jude Children's Research Hospital, Memphis, Tennessee (Z.S.S.); Department of Pathology, Texas Children's Hospital and Baylor College of Medicine, Houston, Texas (V.M., M.D.T., A.M.A.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (J.M.B.); Department of Neurosurgery, The Ohio State University Arthur G. James Cancer Hospital, Columbus, Ohio (V.K.P.)
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Ahmed R, Oborski MJ, Hwang M, Lieberman FS, Mountz JM. Malignant gliomas: current perspectives in diagnosis, treatment, and early response assessment using advanced quantitative imaging methods. Cancer Manag Res 2014; 6:149-70. [PMID: 24711712 PMCID: PMC3969256 DOI: 10.2147/cmar.s54726] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Malignant gliomas consist of glioblastomas, anaplastic astrocytomas, anaplastic oligodendrogliomas and anaplastic oligoastrocytomas, and some less common tumors such as anaplastic ependymomas and anaplastic gangliogliomas. Malignant gliomas have high morbidity and mortality. Even with optimal treatment, median survival is only 12–15 months for glioblastomas and 2–5 years for anaplastic gliomas. However, recent advances in imaging and quantitative analysis of image data have led to earlier diagnosis of tumors and tumor response to therapy, providing oncologists with a greater time window for therapy management. In addition, improved understanding of tumor biology, genetics, and resistance mechanisms has enhanced surgical techniques, chemotherapy methods, and radiotherapy administration. After proper diagnosis and institution of appropriate therapy, there is now a vital need for quantitative methods that can sensitively detect malignant glioma response to therapy at early follow-up times, when changes in management of nonresponders can have its greatest effect. Currently, response is largely evaluated by measuring magnetic resonance contrast and size change, but this approach does not take into account the key biologic steps that precede tumor size reduction. Molecular imaging is ideally suited to measuring early response by quantifying cellular metabolism, proliferation, and apoptosis, activities altered early in treatment. We expect that successful integration of quantitative imaging biomarker assessment into the early phase of clinical trials could provide a novel approach for testing new therapies, and importantly, for facilitating patient management, sparing patients from weeks or months of toxicity and ineffective treatment. This review will present an overview of epidemiology, molecular pathogenesis and current advances in diagnoses, and management of malignant gliomas.
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Affiliation(s)
- Rafay Ahmed
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Matthew J Oborski
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Misun Hwang
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Frank S Lieberman
- Department of Neurology and Department of Medicine, Division of Hematology/Oncology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - James M Mountz
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
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22
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Genome-wide DNA copy number analysis of desmoplastic infantile astrocytomas and desmoplastic infantile gangliogliomas. J Neuropathol Exp Neurol 2013; 72:807-15. [PMID: 23965740 DOI: 10.1097/nen.0b013e3182a033a0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Little is known about the molecular features of desmoplastic infantile ganglioglioma (DIG) and desmoplastic infantile astrocytoma (DIA). We performed a genome-wide DNA copy number analysis in combination with a multiplex ligation-dependent probe amplification-based analysis of copy number changes of candidate genes in 4 DIAs and 10 DIGs. Molecular inversion probe (MIP) assay showed that large chromosomal alterations were rare among DIG and DIA. Focal recurrent genomic losses were observed in chromosome regions such as 5q13.3, 21q22.11, and 10q21.3 in both DIA and DIG. Principal component analysis did not show any significant differences between the molecular profiles of DIG and DIA, and a hierarchical cluster analysis did not clearly separate the 2 tumor groups according to their molecular profiles. In 6 cases, gain of genomic material at 7q31 (corresponding to MET gene) was found in multiplex ligation-dependent probe amplification (MLPA) analysis. Furthermore, two cases showed gain at 4q12, and a single case showed BRAF mutation. In agreement with previous analyses, this study demonstrates the absence of consistent recurrent chromosomal alterations in DIA and DIG and overall rarity of the BRAF mutation in these tumors. Notably, these results suggest that DIA and DIG represent a histologic spectrum of the same tumor rather than 2 separate entities.
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23
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Reis GF, Bloomer MM, Perry A, Phillips JJ, Grenert JP, Karnezis AN, Tihan T. Pilocytic astrocytomas of the optic nerve and their relation to pilocytic astrocytomas elsewhere in the central nervous system. Mod Pathol 2013; 26:1279-87. [PMID: 23702730 DOI: 10.1038/modpathol.2013.79] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/24/2013] [Accepted: 02/27/2013] [Indexed: 12/13/2022]
Abstract
Pilocytic astrocytoma is a low-grade glioma that affects mostly children and young adults and can occur anywhere in the central nervous system. Pilocytic astrocytoma of the optic nerve is an equally indolent subtype that is occasionally associated with neurofibromatosis type 1. In earlier studies, this subtype was considered within the larger category of 'optic pathway glioma,' which included infiltrating astrocytomas and other hypothalamic tumors. However, there have been suggestions that gliomas in the optic nerve, and especially pilocytic astrocytoma of the optic nerve, are biologically different from tumors within the hypothalamus and other parts of the optic tract. Furthermore, the recent discovery of BRAF duplication and fusion with the KIAA1549 gene is reported to be more typical for posterior fossa tumors, and the rate of this aberration is not well known in pilocytic astrocytoma of the optic nerve. To determine the distinction of pilocytic astrocytoma of the optic nerve from pilocytic astrocytoma of the posterior fossa and to investigate the prevalence of BRAF aberrations, we reviewed the clinicopathological and molecular features of all such patients in our institution. Our study demonstrates that BRAF duplication is more frequent in posterior fossa tumors compared with pilocytic astrocytoma of the optic nerve (P=0.011). However, the rates of phospho-MAPK1 and CDKN2A expression were high in both pilocytic astrocytoma of the optic nerve and posterior fossa pilocytic astrocytoma, suggesting that the MAPK pathway is active in these tumors. Our study supports the notion that BRAF duplication is more typical of posterior fossa pilocytic astrocytoma and that molecular alterations other than KIAA1549 fusion may underlie MAPK pathway activation in pilocytic astrocytoma of the optic nerve.
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Affiliation(s)
- Gerald F Reis
- Neuropathology Unit, Department of Anatomic Pathology, UCSF School of Medicine, San Francisco, CA, USA
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The differential diagnosis of pilocytic astrocytoma with atypical features and malignant glioma: an analysis of 16 cases with emphasis on distinguishing molecular features. J Neurooncol 2013; 115:477-86. [PMID: 24057326 DOI: 10.1007/s11060-013-1249-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 09/05/2013] [Indexed: 10/26/2022]
Abstract
Rare pilocytic astrocytomas (PA) have atypical histologic and clinicoradiologic features that raise the differential diagnosis of glioblastoma. Whether ancillary studies can supplement histopathologic examination in placing these cases accurately on the spectrum of WHO Grade I PA to higher-grade glioma is not always clear, partly because these cases are not common. Here, ten PAs with atypical clinicoradiologic and histologic features and six pediatric glioblastoma multiforme (pGBMs) were analyzed for BRAF V600E, IDH1, IDH2, and TP53 mutations. Ki-67, p53, and p16 protein expression were also examined by immunohistochemistry. BRAF-KIAA1549 fusion status was assessed in the PA subgroup. The rate of BRAF-KIAA1549 fusion was high in these PAs (5/7 tumors) including four extracerebellar examples. A single BRAF V600E mutation was identified in the fusion-negative extracerebellar PA of a very young child who succumbed to the disease. TP53 mutations were present only in malignant gliomas, including three pGBMs and one case designated as PA with anaplastic features (with consultation opinion of pGBM). IDH1 and IDH2 were wild type in all cases, consistent with earlier findings that IDH mutations are not typical in high-grade gliomas of patients ≤14 years of age. Immunohistochemical studies showed substantial overlap in Ki-67 labeling indices, an imperfect correlation between p53 labeling and TP53 mutation status, and complete p16 loss in only two pGBMs but in no PAs. These results suggest that (a) BRAF-KIAA1549 fusion may be common in PAs with atypical clinicoradiologic and histologic features, including those at extracerebellar sites, (b) BRAF V600E mutation is uncommon in extracerebellar PAs, and (c) TP53 mutation analysis remains a valuable tool in identifying childhood gliomas that will likely behave in a malignant fashion.
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Gessi M, Pietsch T. The diagnostic role and clinical relevance of determination of BRAF status in brain tumors. Per Med 2013; 10:405-412. [PMID: 29783415 DOI: 10.2217/pme.13.27] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BRAF protein is a serine/threonine kinase that serves as an immediate downstream effector of the MAPK signaling cascade, a signal transduction pathway that modulates cell proliferation and survival. BRAF alterations leading to MAPK pathway activation have been identified in gliomas and glioneuronal tumors of the CNS. Whereas BRAF mutations have been found in a wide spectrum of CNS tumors, BRAF fusions have been almost exclusively found in pilocytic astrocytomas. BRAF fusion identification provides an additional help in the differential diagnosis of supratentorial gliomas. Although the prognostic significance of BRAF alterations in different CNS tumors is still under investigation, the evidence of BRAF-dependent MAPK-pathway activation in gliomas has moreover drawn attention to the potential use of MEK1/2 and RAF inhibitors in clinical neuro-oncology. Given the promising results of the therapeutic management of several cancer types, clinical studies investigating the suitability of such inhibitors for the therapy of gliomas are ongoing.
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Affiliation(s)
- Marco Gessi
- Institute of Neuropathology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, D-53105, Bonn, Germany.
| | - Torsten Pietsch
- Institute of Neuropathology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, D-53105, Bonn, Germany
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Olar A, Aldape KD. Biomarkers classification and therapeutic decision-making for malignant gliomas. Curr Treat Options Oncol 2013; 13:417-36. [PMID: 22956341 DOI: 10.1007/s11864-012-0210-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OPINION STATEMENT Diffuse gliomas are the most common primary brain tumors, with glioblastoma (GBM) encompassing more than 50 % of all cases. Despite aggressive therapy, patients nearly always succumb to their disease and the survival for patients with GBM is approximately 1 year. During past years, numerous scientific contributions have reshaped the field of neuro-oncology and neuropathology. A series of molecular discoveries have shed light on new pathogenic mechanisms, as well as new prognostic and predictive biomarkers with clinical relevance. The current World Health Organization (WHO) classification system is solely based on morphologic criteria; however, there is accumulated evidence that tumors with similar histology have distinct molecular signatures with a clinically significant impact on treatment response and survival. Molecular markers and signatures could be incorporated into the glioma classification and grading system to mirror the clinical outcomes. Additionally, molecular markers could lead to a redefinition of currently controversial entities, such as mixed oligoastrocytomas. Newly discovered molecular alterations also have the potential to become targets for future drug development. Despite tremendous progress in the past decade, therapeutic progress for diffuse gliomas has been slow. A further understanding of glioma biology, in concert with well-designed clinical trials, is necessary to identify more putative molecular biomarkers and unravel the mysteries in the pathogenic mechanisms that trigger this menacing disease.
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Affiliation(s)
- Adriana Olar
- Department of Pathology and Genomic Medicine, The Methodist Hospital, 6565 Fannin St, M227, Houston, TX 77030, USA.
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Abstract
Tumours of the spinal cord, although rare, are associated with high morbidity. Surgical resection remains the primary treatment for patients with this disease, and offers the best chance for cure. Such surgical procedures, however, carry substantial risks such as worsening of neurological deficit, paralysis and death. New therapeutic avenues for spinal cord tumours are needed, but genetic studies of the molecular mechanisms governing tumourigenesis in the spinal cord are limited by the scarcity of high-quality human tumour samples. Many spinal cord tumours have intracranial counterparts that have been extensively studied, but emerging data show that the tumours are genetically and biologically distinct. The differences between brain and spine tumours make extrapolation of data from one to the other difficult. In this Review, we describe the demographics, genetics and current treatment approaches for the most commonly encountered spinal cord tumours--namely, ependymomas, astrocytomas, haemangioblastomas and meningiomas. We highlight advances in understanding of the biological basis of these lesions, and explain how the latest progress in genetics and beyond are being translated to improve patient care.
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Phillips JJ, Aranda D, Ellison DW, Judkins AR, Croul SE, Brat DJ, Ligon KL, Horbinski C, Venneti S, Zadeh G, Santi M, Zhou S, Appin CL, Sioletic S, Sullivan LM, Martinez-Lage M, Robinson AE, Yong WH, Cloughesy T, Lai A, Phillips HS, Marshall R, Mueller S, Haas-Kogan DA, Molinaro AM, Perry A. PDGFRA amplification is common in pediatric and adult high-grade astrocytomas and identifies a poor prognostic group in IDH1 mutant glioblastoma. Brain Pathol 2013; 23:565-73. [PMID: 23438035 DOI: 10.1111/bpa.12043] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 02/11/2013] [Indexed: 11/29/2022] Open
Abstract
High-grade astrocytomas (HGAs), corresponding to World Health Organization grades III (anaplastic astrocytoma) and IV (glioblastoma; GBM), are biologically aggressive, and their molecular classification is increasingly relevant to clinical management. PDGFRA amplification is common in HGAs, although its prognostic significance remains unclear. Using fluorescence in situ hybridization (FISH), the most sensitive technique for detecting PDGFRA copy number gains, we determined PDGFRA amplification status in 123 pediatric and 263 adult HGAs. A range of PDGFRA FISH patterns were identified and cases were scored as non-amplified (normal and polysomy) or amplified (low-level and high-level). PDGFRA amplification was frequent in pediatric (29.3%) and adult (20.9%) tumors. Amplification was not prognostic in pediatric HGAs. In adult tumors diagnosed initially as GBM, the presence of combined PDGFRA amplification and isocitrate dehydrogenase 1 (IDH1)(R132H) mutation was a significant independent prognostic factor (P = 0.01). In HGAs, PDGFRA amplification is common and can manifest as high-level and focal or low-level amplifications. Our data indicate that the latter is more prevalent than previously reported with copy number averaging techniques. To our knowledge, this is the largest survey of PDGFRA status in adult and pediatric HGAs and suggests PDGFRA amplification increases with grade and is associated with a less favorable prognosis in IDH1 mutant de novo GBMs.
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Affiliation(s)
- Joanna J Phillips
- Department of Pathology, University of California San Francisco, San Francisco, CA, USA.
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Reactive retinal astrocytic tumors (so-called vasoproliferative tumors): histopathologic, immunohistochemical, and genetic studies of four cases. Am J Ophthalmol 2013; 155:593-608.e1. [PMID: 23219067 DOI: 10.1016/j.ajo.2012.09.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 08/30/2012] [Accepted: 09/04/2012] [Indexed: 11/23/2022]
Abstract
PURPOSE To evaluate the cellular nature of and diagnostic terminology used in connection with acquired retinal "vasoproliferative tumors." DESIGN Retrospective clinicopathologic study. METHODS Clinical records and microscopic slides of 4 enucleated globes were reviewed. Special stains and immunohistochemical probes for CD31, CD34, p53, glial fibrillary acidic protein (GFAP), CD163, and Ki67 (cell replication) were employed; ultrastructural and fluorescence in situ hybridization (FISH) analyses were performed. RESULTS Tumors were located inferotemporally in middle-aged patients. They were uniformly composed of compacted elongated, GFAP-positive spindle cells (due to intermediate filaments identified ultrastructurally) with a Ki67 index of less than 1%. Rosenthal fibers and eosinophilic granular bodies were observed. Hyalinized periodic acid-Schiff-positive vessels were widely separated. CD31 and CD34 revealed a sparse microvasculature. Tumor-associated exudate spread predominantly subretinally. The retinal pigment epithelium had undergone extensive placoid fibrous metaplasia with focal ossification. P53 upregulation, BRAF-KIAA gene rearrangement, and IDH1R132H mutation typically associated with low-grade astrocytic neoplasms were absent. CONCLUSIONS Retinal "vasoproliferative" tumors have been mischaracterized, because they actually display a paucity of microvessels. Proliferating fibrous astrocytes with a very low proliferation index predominate, without immunohistochemical or genetic evidence favoring a neoplasm. Subretinal exudate appeared capable of provoking widespread fibrous metaplasia of the pigment epithelium that was mainly responsible for secondary retinal damage. The term "reactive retinal astrocytic tumor" is proposed as more appropriate for this entity. In carefully selected progressive lesions, consideration should be given to earlier surgical intervention before extensive subretinal exudate accumulates and pigment epithelial proliferation with fibrous metaplasia ensues.
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Abstract
Glioblastomas with a proneural expression signature are characterized by frequent IDH1 mutations (i.e. genetic hallmarks of secondary glioblastomas) and PDGFRA (platelet-derived growth factor receptor-α) amplification. Mutations in IDH1/2 are frequent and early genetic events in diffuse astrocytomas (World Health Organization grade II), precursor to secondary glioblastomas, but little is known about the role and timing of PDGFRA amplification in these tumors. We assessed PDGFRA gain in 342 low-grade diffuse gliomas by quantitative polymerase chain reaction. Gain in PDGFRA was detected in 27 (16.3%) of 166 diffuse astrocytomas, significantly more frequent than in oligodendrogliomas (3 [2.6%] of 115, p < 0.0001). Analyses using previously published data from our laboratory showed an inverse correlation between PDGFRA gain and IDH1/2 mutations (p = 0.018) or 1p/19q loss (p < 0.0001). The vast majority of diffuse astrocytomas showed IDH1/2 mutations and/or PDGFRA gain (154 [93%] of 166). Mean survival of diffuse astrocytoma patients with PDGFRA gain was 8.8 ± 1.6 years, similar to that with IDH1/2 mutations (7.8 ± 0.5 years) or TP53 mutations (7.6 ± 0.6 years) but significantly longer than those with MET gain (4.4 ± 0.7 years). Dual-color fluorescence in situ hybridization in 6 diffuse astrocytomas with PDGFRA/MET co-gain identified by quantitative polymerase chain reaction revealed that PDGFRA and MET were typically amplified in different tumor cell populations. Tumor cells with coamplification were also focally observed, suggesting intratumoral heterogeneity, even in diffuse astrocytomas.
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