Histopathology and Molecular Diagnostics of Gliomas

Transcription

1 Histopathology and Molecular Diagnostics of Gliomas Laboratory Medicine Seminar Series Bridget Herschap, M.D. February 27, 2012

2 Objectives Overview of Malignant Gliomas Histopathology of Malignant Gliomas Molecular and Chromosomal AbnormaliHes of Malignant Gliomas Future of Molecular DiagnosHcs of Gliomas

3 Malignant Gliomas AstrocyHc tumors Diffuse astrocytoma Low grade astrocytoma AnaplasHc astrocytoma Glioblastoma MulHforme Oligodendrogliomas Low grade oligodendroglioma AnaplasHc oligodendroglioma Oligoastrocytomas Low grade oligoastrocytoma

4 Astrocytic Tumors

5 Diffuse Astrocytoma Incidence and LocaHon Accounts for roughly 40% of primary intracranial neoplasms Annual incidence rate of roughly 4 per 100,000 person- years Most arise in the cerebral hemispheres with a subcorhcal epicenter, but they may be seen anywhere along the neural axis, including the brain stem, cerebellum, and spinal cord

6 Diffuse Astrocytoma Gender and Age DistribuHon Slight male preponderance (M/F raho of 3 : 2) Can occur at any age, although the incidence increases with advancing age Older pahents are more likely to have higher- grade gliomas, especially glioblastoma Clinical Features ManifestaHons dependent on locahon of tumor Rapid onset and progression suggest high grade (III or IV), whereas a protracted history is more consistent with low grade (II)

7 Diffuse Astrocytoma Gross Findings Borders are ill defined, and there are oyen foci of tumor involvement that are grossly invisible, parhcularly in gliomatosis cerebri Tumor epicenter most common in white ma[er or deep gray ma[er (e.g., thalamus or basal ganglia) Blurring of corhcomedullary and other gray- white junchons Mass effect with a midline shiy, blunhng of sulci, compression of ventricles, or any combinahon of these effects A variegated appearance with foci of necrosis and hemorrhage suggests glioblastoma Foci of radiahon necrosis may appear grossly similar to glioblastoma

8 Diffuse Astrocytoma Microscopic Features Hypercellularity with intermingling of neoplashc and non- neoplashc elements (i.e., infiltrahve) HyperchromaHc oval to spindled nuclei with irregular contours Mild to moderate nuclear atypia Either no discernible cytoplasm ( naked nuclei ) or eosinophilic cytoplasmic processes Secondary structures of Scherer are less common than in oligodendrogliomas, but occasionally prominent MitoHc figures/increased proliferahon present in grades III and IV Endothelial hyperplasia or necrosis (or both) present in glioblastoma (grade IV)

9 Diffuse Astrocytoma Immunohistochemical Features GFAP: usually posihve, but somehmes difficult to dishnguish brain from tumor immunoreachvity S- 100 protein: posihve; less specific, but more sensihve than GFAP for glial lineage CytokeraHns: negahve, but may get false- posihve result with AE1/ AE3 cocktail Epithelial membrane anhgen (EMA): negahve HMB- 45, melan A, leukocyte common anhgen (LCA): negahve Neurofilament highlights entrapped axons, consistent with an infiltrahve growth pa[ern p53 protein posihve in more than half MIB- 1 (Ki- 67) labeling index roughly proporhonal to grade

10

11

12 Diffuse Astrocytoma Prognosis and Treatment PaHent age: powerful predictor, with survival inversely proporhonal to pahent age Histologic grade: survival averages 5 to 10 years for grade II, 2 to 3 years for grade III, and 1 year for grade IV Histologic cell type PreoperaHve performance status Extent of resechon Radiotherapy oyen used to treat subtotally resected and higher- grade gliomas Chemotherapy oyen used in high- grade (III or IV)

13 Oligodendrogliomas

14 Oligodendrogliomas Incidence and LocaHon Accounts for 10% to 25% of diffuse gliomas Annual incidence rate of roughly 0.6 per 100,000 person- years Most arise in the cerebral hemispheres More than half occur in the frontal lobes Gender and Age DistribuHon Slight male preponderance (M/F raho of 3 : 2) Can occur at any age, although peak at 40 to 45 years Rare in children

15 Oligodendrogliomas Gross Findings Borders are ill- defined and there are oyen foci of tumor involvement that are grossly invisible Tumor epicenter most commonly in the cortex or corhcomedullary junchon Blurring of corhcomedullary and other gray- white junchons A variegated appearance with foci of necrosis and hemorrhage suggests anaplasia

16 Oligodendrogliomas Microscopic Features Hypercellularity with intermingling of neoplashc and non- neoplashc elements, but may have solid- appearing foci as well Uniformly round to oval nuclei with bland chromahn and, oyen, small nucleoli Clear perinuclear halos impart a fried- egg appearance Minigemistocytes maintain the nuclear features, but contain small rounded bellies of eosinophilic cytoplasm Mucin- rich microcyshc spaces common MicrocalcificaHons common and may be extensive in some Rich branching capillary network resembling chicken wire Secondary structures and tumor clusters or hypercellular nodules common AnaplasHc (grade III) examples have frequent mitoses, endothelial hyperplasia, or both, oyen with increased pleomorphism and epithelioid cytology

17 Immunohistochemical Features GFAP: usually negahve in classic cells, but strongly posihve in two cell types minigemistocytes (rounded eccentric cytoplasmic belly) and gliofibrillary oligodendrocytes (thin rim of perinuclear staining, with or without a thin cytoplasmic tail) S- 100 protein: posihve CytokeraHns: negahve, but may get false- posihve result with an AE1/AE3 cocktail EMA: negahve HMB- 45, melan A, LCA: negahve Neurofilament highlights entrapped axons, consistent with an infiltrahve growth pa[ern p53 protein usually negahve MIB- 1 labeling index typically elevated in anaplashc examples

18

19

20 Oligodendrogliomas Prognosis and Treatment PaHent age: powerful predictor, with survival inversely proporhonal to pahent age Grade: survival averages 10 to 15 years for grade II and 3 to 5 years for grade III Histologic cell type PreoperaHve performance status Extent of resechon Radiotherapy oyen used to treat pahents with subtotal resechon, anaplasia, or older age (e.g., >40 years) Chemotherapy oyen used in oligodendroglial tumors, parhcularly those with chromosome 1p and 19q delehons

21 Oligoastrocytomas

22 Oligoastrocytomas Incidence and LocaHon Accounts for 5% to 15% of diffuse gliomas Annual incidence rate of roughly 0.4 per 100,000 person- years Most arise in the cerebral hemispheres Gender and Age DistribuHon Slight male preponderance (M/F raho of 3 : 2) Can occur at any age, although peak at 40 to 45 years Rare in children

23 Oligoastrocytomas Gross Findings Borders are ill- defined, and there are oyen foci of tumor involvement that are grossly invisible Generally indishnguishable from other forms of diffuse gliomas Blurring of corhcomedullary and other gray- white junchons A variegated appearance with foci of necrosis and hemorrhage suggests anaplasia

24 Oligoastrocytomas Microscopic Features Hypercellularity with intermingling of neoplashc and non- neoplashc elements, but may have solid- appearing foci as well Same features as pure astrocytomas and oligodendrogliomas, but both present Intermixed variant more common than the biphasic variant, and some nuclei may have features intermediate between those of astrocytoma and oligodendroglioma AnaplasHc (grade III) examples have frequent mitoses or endothelial hyperplasia, or both, oyen with increased pleomorphism Glioblastoma with an oligodendroglial component (grade IV) addihonally shows foci of tumor necrosis

25

26 Oligoastrocytomas Prognosis and Treatment PaHent age: powerful predictor, with survival inversely proporhonal to pahent age Grade: survival averages 5 to 10 years for grade II and 2 to 4 years for grade III Histologic cell type: mixed oligoastrocytomas have a prognosis intermediate between that of pure oligodendrogliomas and astrocytomas PreoperaHve performance status Extent of resechon Radiotherapy oyen used to treat pahents with subtotal resechon, anaplasia, or older age (e.g., >40 years) Chemotherapy oyen used as in pure oligodendrogliomas, parhcularly those with chromosome 1p and 19q delehons

27 Oligoastrocytomas Most cases are either genehcally similar to pure astrocytomas or pure oligodendrogliomas throughout the tumor regardless of regional differences in histology (i.e., monoclonal). CodeleHon of one 1p and one 19q arm in roughly 20% of intermixed and 50% of biphasic examples; yet to be determined is whether the same prognoshc implicahons generally apply as they do with pure oligodendrogliomas

28 Molecular Diagnostics

29 Molecular Diagnostics Combined delehon of chromosome arms 1p and 19q IDH1 and IDH2 mutahons MGMT hypermethylahon EGF receptor aberrahons

30 Combined 1p/19q loss

31 Combined 1p/19q loss GeneHc hallmark of oligodendroglial tumors Strong correlahon between classical oligodendroglial histology Complete chromosomal arm loss Result of unbalanced centromeric translocahon No tumorigenic genes implicated in the 1p and 19q regions

32 Combined 1p/19q loss Frequency Grade II oligodendrogliomas: 80-90% Grade III oligodendrogliomas: 50-70% Oligoastrocytomas: 30-50% AnaplasHc oligoastrocytomas: 20-30% Diffuse astrocyhc gliomas: <10%

33

34 Combined 1p/19q loss Cairncross and colleagues documented that recurrent anaplashc oligodendrogliomas with loss of the short arm of chromosome 1 (1p) were preferenhally chemosensihve when treated with a procarbazine, lomushne, and vincrishne chemotherapy regimen. PaHents whose tumors had co- delehons of 1p and the long arm of chromosome 19 (19q) had substanhally improved survival Hmes.

35 Survival Anaplas(c Oligodendrogliomas Response Rate Response DuraHon 1p loss 1p intact 1p/19q 1p/other p53 mut No p53 mut 100% 100% 33% 18% >31 months 11 months 7 months 5 months Survival >123 months 71 months 71 months 16 months Possible Treatment PCV>?RT PCV + RT PCV +RT RT + new txt Louis DN, Holland EC, Cairncross JG. AJP 2001

36 Combined 1p/19q loss PrognosHc power was independent of the type of adjuvant therapy RetrospecHve data on oligodendroglial tumor pahents not receiving any adjuvant therapy ayer their inihal surgical treatment revealed that 1p/19q loss was not associated with longer progression- free survival 1p/19q loss characterizes a group of gliomas that is more sensihve to genotoxic therapy and, when treated, are associated with significantly longer survival.

37 Combined 1p/19q loss In addihon, different types of 1p losses have been idenhfied that have dishnct prognoshc implicahons. Oligodendroglial tumors carrying parhal terminal or intershhal 1p losses are associated with shorter pahent survival when compared with tumors with combined complete 1p/19q losses However, while 1p/19q loss is associated with more favorable prognosis of pahents receiving adjuvant treatment, it needs to be emphasized that this marker is of limited help for making treatment decisions, such as radiotherapy versus chemotherapy.

38 Method Required Material Read out Advantages/ Disadvantages

39

40 IDH1 and IDH2 mutations

41 IDH1 and IDH2 mutations MutaHons in the gene encoding the human cytosolic NADPH- dependent isocitrate dehydrogenase (IDH1). MutaHons were found in the evoluhonarily conserved residue R132 that is located in the substrate- binding site of IDH1 In a small subset of diffuse gliomas and secondary glioblastomas that lack IDH1 mutahons, the gene of the mitochondrial isoform IDH2 was found to harbor mutahons.

42 IDH1 and IDH2 mutations Possible role in oncogenic acevaeon: IDH1 mutaeons lead to increased formahon of R( )2- hydroxyglutarate, which might be directly oncogenic. Reduced catalyhc ability of IDH might lead to increased levels of the transcriphon factor hypoxia- inducible factor- α, known to facilitate tumor growth.

43 IDH1 and IDH2 mutations Frequency: Primary glioblastomas: 0.05% Secondary glioblastomas 84.6% Diffuse astrocytomas 83.3% AnaplasHc astrocytomas 69.2% Oligodendrogliomas 80.4% AnaplasHc oligodendrogliomas 86.1% Oligoastrocytomas 100%

44 IDH1 and IDH2 mutations An improved outcome for pahents with tumors with IDH1 and IDH2 mutahons. Glioblastomas: median survival 31 months versus 15 months AnaplasHc astrocytomas: median survival 65 months versus 20 months In contrast to the strong prognoshc significance, several studies reported a lack of predichve significance of IDH1 mutahons in gliomas for response to chemotherapy.

45 IDH1 and IDH2 mutations Low grade, infiltrahng gliomas might prove diagnoshcally challenging. The presence of mutant IDH1 and IDH2 has potenhal to help idenhfy infiltrahng glial tumors.

46 IDH1 and IDH2 mutations Method Required Material Read out Advantages/ Disadvantages

47 IDH1 and IDH2 mutations

48 MGMT hypermethylation

49 MGMT hypermethylation MethylaHon of the MGMT gene promoter leads to down regulahon of MGMT expression. Currently, glioblastoma are treated with the orally administered alkylahng drug temozolomide. methylates the O6 posihon of the nucleohde guanine resulhng in cell death Cells typically have an inherent DNA repair mechanism that can counter the effects of temozolomide. The conshtuhvely expressed DNA repair enzyme MGMT will irreversibly transfer a methyl group from the O6 posihon of the modified guanine to a cysteine residue of the MGMT protein. Decreased cytotoxic effects of chemotherapy

50 MGMT hypermethylation Frequency Glioblastomas: approximately 50% Decreased concentrahons of MGMT could make these tumors more suscephble to the effects of temozolomide. In 106 pahents treated with temozolomide (46 with methylated tumors, 60 with unmethylated tumors), 46% of pahents with MGMT methylated tumors were alive at 2 years versus 23% of pahents with tumors with unmethylated MGMT.

51 MGMT hypermethylation The prognoshc informahon of the MGMT methylahon status appears to apply only to primary tumors and not to recurrent tumors. MethylaHon pa[erns of the MGMT promoter might change in the Hme between primary diagnosis and recurrence, and might change more frequently in tumors that inihally show MGMT methylahon.

52 MGMT hypermethylation MGMT promoter methylahon status can be useful in the differenhal diagnosis of true tumor progression versus pseudoprogression seen on imaging. In this case, for a tumor with MGMT promoter methylahon, pseudoprogression might be more likely than true progression and thus therapy with temozolomide is oyen conhnued despite the worse appearance on neuroimaging. Conversely, a worsening appearance on imaging in a pahent whose glioblastoma does not have MGMT promoter methylahon might prompt considerahon to change therapy.

53 MGMT hypermethylation Method Required Material Read out Advantages/ Disadvantages

54

55 EGF Receptor aberrations The future for treatment of glioblastomas?

56 EGF Receptor aberrations The EGFR gene is located on chromosome 7p12. An upregulahon of EGFR- mediated signaling is seen in 60% of glioblastomas with over expression generally driven by EGFR gene amplificahon. In approximately half of glioblastomas that overexpress EGFR there is also expression of mutant forms of EGFR molecules. EGFR variant III (EGFRvIII) ConsHtuHvely achvates the EGFR- phosphoinosihde 3- kinase pathway.

57 EGF Receptor aberrations The presence of EGFR overexpression and EGFR mutahons in glioblastomas raises the possibility that EGFR- targeted drugs could be used to treat pahents who have glioblastomas with these aberrahons a similar situahon to that of non- small- cell lung carcinomas that have achvahng EGFR mutahons and that show remarkable responses to the EGFR inhibitors erlohnib and gefihnib.

58 EGF Receptor aberrations Small cell variant of glioblastomas, not staining strongly for GFAP, could be confused for high- grade oligodendroglial tumors. EGFR gene amplificahon present in 71% of small cell glioblastomas.

59 Future of Molecular Diagnostics

60 Resources Dr. Henry Dr. Fan Parsons DW, Jones S, Zhang X, et al. An integrated genomic analysis of human glioblastoma mulhforme. Science 2008; 321: Hau P, Stupp R, Hegi ME. MGMT methylahon status: the advent of strahfied therapy in glioblastoma? Dis Markers 2007; 23: Jansen M, Yip S, Louis D. Molecular pathology in adult gliomas: diagnoshc, prognoshc, and predichve markers. The Lancet 2010; 9: Nikiforova M, Hamilton R. Molecular DiagnosHcs of Gliomas. Archives of Pathology 2010; 135: Riemenschneider M; Jeuken J; et al. Molecular diagnoshcs of gliomas: state of the art. Acta Neuropathol 2010; 120: Prayson R. Neuropathology: A Volume in the FoundaHons in DiagnosHc Pathology Series. 1 ed.philadelphia, PA: Elseiver; 2005.