Mark W. Kieran, MD, PhD

Pediatric Subcommittee for ODACBiology of Pediatric Brain Tumors and the

Heterogeneity of the Disease

Children’sHospitalBoston

Dana-FarberCancerInstitute

HarvardMedicalSchool

Objectives

• Review of the biology of pediatric brain tumors– Are adult and pediatric tumors of the CNS different

and will that impact on the applicability of adult studies regarding safety and efficacy

• Development of better endpoints and trial design in pediatric CNS tumors

– improve approval of drugs (standard and biologic) for this population

BackgroundDifferences Between Adult and

Pediatric CNS Tumors

• Site of origin of tumor• Histology of tumor• Presentation (related to site)• Dissemination (related to

histology)

Risk Stratification by Disease Location

• Glial– Brain stem location (pons versus other)– Brain stem versus non-brain stem– Bithalamic LGGs versus bilateral optic radiations– Diencephalic syndrome

• Neural– Posterior fossa– Pineal– Supratentorial– Infratentorial

Risk Stratification by Disease Histology

• Glial– Grade I vs II vs III vs IV astrocytomas

• Sampling errors– Diffuse pontine glioma (independent of histology) versus other HGG– LGG +/- NF1 (COG A9952)– Grade II versus grade III ependymoma– 1p, 19q loss in oligodendroglioma

• Neural– Chang staging for medullo– ATRT– Pineoblastoma versus PNET

• Choroid Plexus and Craniopharyngiomas will require a unique pediatric commitment (virtually absent in adults)

Risk Stratification by Age

• Glial– Grade II LGG Grade III AA in adults but rarely do so in peds

(while pilocytic astrocytomas behave similarly after GTR in both)

– Pediatric LGG often chemo responsive (not clearly the same in adults although not tested)

– Primary (EGFR VIII+ve, p53 wt) and secondary GBM (EGFR wt, p53-ve) in adults versus only primary GBM in peds (and not EGFR mutated or p53 mutant – depending on the series)

– Rarity of oligodendroglioma in peds vs adults– Abundance of ependymomas in peds vs adults

• Neural– Desmoplastic medullo in infants– Outcome in adults versus children

Etiology of Disease and Age Differences

• The result of differences in up-front treatment– Medullo outcome worse in adults, but less therapy given

• The result of differences in the origin and stage of the ‘cancer stem cell’

– Adult HGGs have frequent p53, VIII EGFR mutations, which are rare in peds

• The result of differences in the tumor cell environment of the brain

– Optic pathway gliomas and role of CXCR4

Markers for Pediatric CNS Tumors

• Molecular markers of prognosis could improve:– Diagnosis– Treatment

• Pediatric classification schema integrating:– Histology– Molecular– Neurobiologic– Neuroimaging

Advances in Neuro-Radiology

T1W Gd ADC (Diff) rCBV (Perf)

31

2

4

1

31

2

43

1

2

4

Cho

tCr 2Cho

L

3

L

4

Cho

NAAtCr

MR

Fused

F18 FDGPET

MD MGlio Rhab NC PNET

Distinction Feature Descclass 0 M93119_at INSM1 Insulinoma-associated 1 (symbol provisional)class 0 M30448_s_at Casein kinase II beta subunit mRNAclass 0 S82240_at RhoEclass 0 U44060_at Homeodomain protein (Prox 1) mRNAclass 0 D80004_at KIAA0182 gene, partial cdsclass 0 D76435_at Zic proteinclass 0 X83543_at APXL Apical protein (Xenopus laevis-like)class 0 X62534_s_at HMG2 High-mobility group (nonhistone chromosomal) protein 2class 0 Y10514_s_at CD152 proteinclass 0 M96739_at NSCL-1 mRNA sequenceclass 1 X86693_at High endothelial venuleclass 1 M93426_at PTPRZ Protein tyrosine phosphatase, receptor-type, zeta polypeptideclass 1 U48705_rna1_s_atReceptor tyrosine kinase DDR geneclass 1 X86809_at Major astrocytic phosphoprotein PEA-15class 1 U45955_at Neuronal membrane glycoprotein M6b mRNA, partial cdsclass 1 U53204_at Plectin (PLEC1) mRNAclass 1 X13916_at LDL-receptor related proteinclass 1 D87258_at Cancellous bone osteoblast mRNA for serin protease with IGF-binding motifclass 1 Z31560_s_at SOX2 SRY (sex determining region Y)-box 2class 1 M32886_at SRI Sorcinclass 2 J04164_at RPS3 Ribosomal protein S3class 2 M12125_at Skeletal beta-tropomyosinclass 2 D17400_at PTS 6-pyruvoyltetrahydropterin synthaseclass 2 D29958_at KIAA0116 gene, partial cdsclass 2 D84454_at UDP-galactose translocatorclass 2 D83174_s_at CBP1 Collagen-binding protein 1class 2 D83735_at Adult heart mRNA for neutral calponinclass 2 L38969_at Thrombospondin 3 (THBS3) geneclass 2 U12465_at RPS11 Ribosomal protein S11class 2 U47621_at Nucleolar autoantigen No55 mRNAclass 3 D87463_at KIAA0273 geneclass 3 U90902_at Clone 23612 mRNA sequenceclass 3 D26070_at Type 1 inositol 1,4,5-trisphosphate receptorclass 3 X63578_rna1_atParvalbuminclass 3 Z15108_at PRKCZ Protein kinase C, zetaclass 3 L35592_at Germline mRNA sequenceclass 3 L10338_s_at SCN1B Sodium channel, voltage-gated, type I, beta polypeptideclass 3 L33243_at PKD1 Polycystic kidney disease protein 1class 3 L77864_at Stat-like protein (Fe65) mRNAclass 3 J04469_at Mitochondrial creatine kinase (CKMT) geneclass 4 M80397_s_at POLD1 Polymerase (DNA directed), delta 1, catalytic subunit (125kD)class 4 X14830_at CHRNB1 Cholinergic receptor, nicotinic, beta polypeptide 1 (muscle)class 4 K02882_cds1_s_atIGHD gene (immunoglobulin delta-chain) extracted from Human germline IgD chain gene, C-region, C-delta-1 domainclass 4 HG4178-HT4448_atAf-17class 4 U97018_at Echinoderm microtubule-associated protein homolog HuEMAP mRNAclass 4 X52228_at MUC1 Mucin 1, transmembraneclass 4 L18920_f_at MELANOMA-ASSOCIATED ANTIGEN 2class 4 X55668_at PRTN3 Proteinase 3 (serine proteinase, neutrophil, Wegener granulomatosis autoantigen)class 4 U64805_s_at Brca1-delta11b (Brca1) mRNAclass 4 X98337_s_at Complement factor H-related protein 4

Tumor Specific Gene Expression Profiles

Pomeroy et al., Nature 2002

Advances in Neuropathology

Maldi-TOF profile

SELDI-TOF Angiogenesis Proteomic Profile

VEGF-A Expression (#4)

pVEGFR2 Expression (#4)

A. Solid tumor H&EB. EGFR +ve area (40X)C. EGFR -ve area (10X)

D. Infiltrative tumor H&EE. EGFR +ve cells (10X)F. EGFR +ve cells (40X)

The dense tumor with strong +ve EGFR staining (B), dense tumorwith -ve EGFR staining (C) and the infiltrative cerebellum with occasional +ve EGFR cells (E&F) are all derived from the same patient

EGFR Expression in Pediatric Diffuse Pontine Glioma

EGFR Molecular Targeting in BSG

• In spite of significant staining within tumor cells, unclear that this molecular target inhibition alters disease activity.– Problem with target– Problem with heterogeneity of target– Problem with activity of drug

• Wrong dose• Wrong schedule

Targeted Molecular Agents: Malignant Glioma

From Reardon ASCO: 2005

EGFR• Gefitinib (ZD1839, Iressa)• Erlotinib (OSI-774, Tarceva)• Lapatinib (GW-572016)• AEE788• ZD6474

Farnesyltransferase• Tipifarnib (R115777, Zarnestra)• Lonafarnib (Sch66336, Sarasar)

Histone Deacetylase• Depsipeptide• Suberoylanilide hydroxamic acid (SAHA)

Integrins• Cilengitide (EMD 121974)• M200

mTOR• Temsirolimis (CCI 779)• Everolimus (RAD 001)• Rapamycin (Sirolimus)• AP23573

VEGF/VEGFR• Avastin (Bevacizumab)• Sorafenib (Bay 43-9006)• Semaxanib (SU5416)• PTK787• SU011248• AEE788• AZD2171• ZD6474• AMG 706• GW786034• CEP-7055

PDGF• Gleevec (imatinib mesylate)• PTK787• SU101• SUO11248•GW786034• MLN518

PKC• Tamoxifen

PKC 2• Enzastaurin (LY317615)

Proteosome• Bortezomib (Velcade)

RAF kinase• Sorafenib (Bay 43-9006)

TGF-/TGF- Receptor• SB-431542• AP12009

RR

K K

PI3K RasGTP

PLC

Raf

MEK1,2

MAPK/Erk1,2

AktPKC

mTOR

FKHR, GSK-3, Bad

PDKPTEN

HIF 1VEGF

Angiogenesis ProliferationTranscription

cytosol

cytoplasmic membrane

Protein-synthesis

Cell cycle regulationCell survival

extracellular compartment

VEGF, EGFR, PDGFR, IGFR1

intracellular compartment

Ligands/growth factors

From Reardon ASCO: 2005

RR

K K

PI3K RasGTP

PLC

Raf

MEK1,2

MAPK/Erk1,2

AktPKC

mTOR

FKHR, GSK-3, Bad

PDKPTEN

VEGF

Angiogenesis ProliferationTranscription

cytoplasmic membrane

Protein-synthesis

Cell cycle regulationCell survival

extracellular compartment

EGFR, PDGFR, IGFR1intracellular compartment

Ligands/growth factors

Toxin-conjugatesMR-I; TP-38

TarcevaGefitinibAEE788Gleevec

FTIs: Tipifarnib, Lonafarnib

RapamycinRAD001AP23573CCI 779

PTK787AEE788Avastin

Sorafenib

From Reardon ASCO: 2005

Tracer uptake was assessed by μSPECT in v3 integrin positive (U87) and negative (Hela) tumors, with only the v3 positive tumor showing uptake. In the same animal, tracer uptake was blocked by pre-injection of an unlabeled v3-

directed agent (EMD121974, Merck KGaA).

Validation of receptor-specific tracer uptake in xenografts

3-D reconstruction of intracranial μSPECT data

Intracranial Glioma MR and SPECT Co-registration

Excellent spatial resolution of multiple tiny intracranial

tumors

For perspective- the whole mouse brain is about the size of a dime, &each tumor is the same diameter as one of the letters in the word ‘Liberty’

What makes μSPECT special?

Summary

• There are significant differences in adult and pediatric brain tumors– Sometimes related to location– Sometimes related to histology/cell of origin– Sometimes related to age

• There are increasing numbers of molecular inhibitors– Specific agents against specific targets often do not

result in specific activity• Molecular markers of activity