Molecular diagnostics in
pediatric glial tumors
Joon-Hyung Kim, MSIV
Weill Cornell Medical College
Key molecular alterations in pediatric glial tumors
Tumor type
Molecular phenotype
Association
Oligodendroglioma
1p/19q codeletion
Adults > Peds
Ganglioglioma
BRAF V600E
Peds > Adults
PXA
BRAF V600E
Peds = Adults
Mesenchymal histology
Pilocytic astrocytoma
BRAF-KIAA1549
Tumor location/resectability
(Cerebellar > Non-cerebellar)
DIPG
1q gain, 17p loss
H3F3A, HIST1H3B
mutations (K27M)
Peds > Adults
DIPG > Non-Brainstem pGBM
pGBM
H3F3A mutation
Peds > Adults
GBM > WHO I,II,III gliomas
Peds > Adults
Type of H3F3A mutation
(G34R/V > K27M)
ATRX, DAXX mutation
ATRX mutation
Anaplastic oligodendroglioma in adults (n=64)
Progression Free Survival
Overall Survival
Snuderl et al. Clin Cancer Res 2009.
1p/19q codeletion
1p/19q codeletion
with polysomy
“relative deletion”
No 1p/19q
codeletion
1p and 19q deletions are infrequent
in pediatric oligodendroglioma
Series
N
Age
1p
del
19q
del
1p/19q
del
MGMT
met
IDH1
mut
TP53
mut
Pollack et al., 2003
8
NA
1
2
NA
NA
NA
NA
Raghavan et al. 2003
15
2-9
0
0
0
NA
NA
NA
11
10-18
2
0
3
NA
NA
NA
Kreiger et al., 2005
13
5-18
1
0
0
NA
NA
NA
Suri et al., 2011
7
3-18
0
0
0
5
0
0
Creach et al., 2012
15
1-18
NA
NA
2
NA
NA
NA
Total
69
1-18
4 (7.4%)
2 (3.7%)
5 (8.2%)
5 (71%)
0
0
Tumor type
Molecular phenotype
Association
Oligodendroglioma
1p/19q codeletion
Adults > Peds
Ganglioglioma
BRAF V600E
Peds > Adults
PXA
BRAF V600E
Peds = Adults
Mesenchymal histology
Pilocytic astrocytoma
BRAF-KIAA1549
Tumor location/resectability
(Cerebellar > Non-cerebellar)
DIPG
1q gain, 17p loss
H3F3A, HIST1H3B
mutations (K27M)
Peds > Adults
DIPG > Non-Brainstem pGBM
pGBM
H3F3A mutation
Peds > Adults
GBM > WHO I,II,III gliomas
Peds > Adults
Type of H3F3A mutation
(G34R/V > K27M)
ATRX, DAXX mutation
ATRX mutation
BRAF V600E in Ganglioglioma in Children
MacConaill et al. 2009
Schindler et al. 2011
BRAF V600E in Ganglioglioma and Pleomorphic
Xanthoastrocytoma in Children < 18 years
Pediatric Ganglioglioma
% BRAF V600E
MacConaill et al., 2009
57% (8/14)
Dougherty et al., 2010
50% (9/18)
Schindler et al., 2011
13% (3/24)
Total
36% (20/56)
Pediatric PXA
•
•
Schindler et al., 2011
78% (28/36)
Dias-Santagata et al, 2011
57% (4/7)
Total
74% (32/43)
Initially described in melanoma, colon and papillary thyroid carcinoma
Vemurafenib (“V600E mutated BRAF inhibitor”)
– FDA approved for late-stage or unresectable melanoma (Aug 2011)
Tumor type
Molecular phenotype
Association
Ganglioglioma
BRAF V600E
Peds > Adults
PXA
BRAF V600E
Peds = Adults
Mesenchymal histology
Pilocytic astrocytoma
BRAF-KIAA1549
Tumor location/resectability
(Cerebellar > Non-cerebellar)
Oligodendroglioma
1p/19q codeletion
Adults > Peds
DIPG
1q gain, 17p loss
Peds > Adults
H3F3A, HIST1H3B
mutations (K27M)
DIPG > Non-Brainstem pGBM
H3F3A mutation
Peds > Adults
GBM > WHO I,II,III gliomas
ATRX, DAXX mutation
Peds > Adults
ATRX mutation
Type of H3F3A mutation
(G34R/V > K27M)
pGBM
Unlike in adults, EGFR amplification, PTEN deletion, IDH1 mutations are rarely
observed in pGBM.
`
H3F3A mutations are exclusive
to high grade tumors and occur
in the pediatric setting.
H3F3A, ATRX, and DAXX
mutations distinguish pediatric
from adult GBM.
Schwartzentruber et al., 2012
Tumor type
Molecular phenotype
Association
Ganglioglioma
BRAF V600E
Peds > Adults
PXA
BRAF V600E
Peds = Adults
Mesenchymal histology
Pilocytic astrocytoma
BRAF-KIAA1549
Tumor location/resectability
(Cerebellar > Non-cerebellar)
Oligodendroglioma
1p/19q codeletion
Adults > Peds
DIPG
1q gain, 17p loss
Peds > Adults
H3F3A, HIST1H3B
mutations (K27M)
DIPG > Non-Brainstem pGBM
H3F3A mutation
Peds > Adults
GBM > WHO I,II,III gliomas
ATRX, DAXX mutation
Peds > Adults
ATRX mutation
Type of H3F3A mutation
(G34R/V > K27M)
pGBM
H3F3A is located on chromosome 1q, a region of large-scale chromosomal gain in DIPG.
Adults
Peds
Epigenome
MGMT promoter methylation in
adult GBM (associated with
pseudoprogression s/p TMZ/RT and
improved survival)
H3.3-ATRX-DAXX chromatin remodeling
pathway in pGBM
Chromosome
1p/19q codeletion in adult OGD
1q gain, 17p loss in DIPG
Gene
Adult AA with EGFR amplification
behaves like GBM
EGFR amp, PTEN del are rare in pGBM/DIPG
PDGFRA amp in DIPG
Nucleotide
Protein
IDH1 mutation (R132H) in
secondary GBM and LGG in adults
BRAF mutation (V600E) in ganglioglioma and PXA
BRAF-KIAA1549 in cerebellar PA
PARP-1 overexpression in DIPG
Tumor-derived Exosomes
Electron microscopy of
exosomes derived from U87
cells
• Exosomes are small membrane
vesicles (30-100 nm) derived from
luminal membranes of
multivesicular bodies and released
constitutively by fusion with cell
membrane
• Released from tumor cells,
exosomes mediate local and
systemic cell communication
through horizontal transfer of
information, such as mRNA,
miRNA, proteins, DNA
Research questions:
1. Can exosomes in peripheral blood of glioma patients serve
as biomarkers of tumor progression?
2. Can exosomes in patient plasma reliably predict parent
tumor mutational status in brain?
-IDH1 R132H mutation
-BRAF V600E mutation
DNA is present in tumor cell derived exosomes.
ExoDNA exists predominantly as methylated, single stranded DNA
gDNA exoDNA
DNase - +
- +
10kb
3kb
gDNA
S1 nuclease +
-
exoDNA-1 exoDNA-2
+
+
10kb
3kb
1kb
1kb
Anti-5’metCytosine
Anti-DNA
exoDNA
gDNA
Courtesy of Haiying Zhang and David Lyden
Acknowledgements
Neurosurgery
• Jeffrey Greenfield, MD, PhD
• Michael Kaplitt, MD, PhD
• Philip Stieg, MD, PhD
Pediatrics
• David Lyden, MD, PhD
Neurosurgery
• Philip Gutin, MD
Pathology
• Jason Huse, MD, PhD
Neuroradiology
• Andrei Holodny, MD