Biomarkers in Anatomic Pathology
Adding Value in Diagnostics
Jennifer Hunt, MD, MEd, FCAP
Biomarkers in Anatomic Pathology:
Adding Value in Diagnostics
Jennifer L. Hunt, M.D., M.Ed.
Section Head, Surgical Pathology
Director, Head and Neck and Endocrine Pathology
Director, Molecular Anatomic Pathology Unit
Auguste Nélaton (1807 – 1873)
“The microscope is not, for the biologist or physician,
an instrument which he can indifferently make use of;
its employment is absolutely necessary. Accustomed
to judge from exterior characters alone, pathologists
should not be astonished that many results obtained
by them are shown to be inexact or incomplete by the
microscope. Far from believing that the fault comes
from the new information added by the microscope, it
is the history of diseases which must be taken up
again and revised, starting from the new and much
more precise notions of the tissue furnished by
microscopy.”
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Zaccharias Janssen (15901608): First Microscope
Anton van
Leeuwenhoek (16321723): Bacteria
1600
Robert Hooke
(1635-1703)
Father of
Microscopy
1700
Rudolph Virchow
(1821-1902):
Father of
Microscopic
Pathology
1800
1900
Carl Rokitansky (18041878): Father of
Autopsy Pathology
Peyton Rous (1910): Oncogenes
(Nobel Prize 1966)
Ernst Ruska & Max Knott (1931):
Electron Microscope (Nobel Prize,
1986)
Kary Mullis (1983):
Polymerase Chain
Reaction (Nobel
Prize, 1993)
Frederick Sanger (1975):
Sequencing (Nobel Prize, 1980)
1950
1960
Watson & Crick
(1953): DNA
(Nobel Prize,
1962)
1970
1980
Alfred Knudson
(1971): Tumor
suppressor
genes (Lasker
Award, 1998)
1990
2000
Sternberger
(1978): Immunocytochemistry
Gross Exam (1500-1800)
Microscopic Analysis
(1800-1930)
Electron Microscopy
(1930-1980)
IHC (1980-2000)
DNA
(2000)
Micro
Agenda: Biomarkers in AP
• The Past: Diagnosis
• The Present: Prognosis
• The Future: Therapeutics
1800
Diagnostic
Assay Era
1960
Prognostic
Assay Era
2000
Therapeutic
Assay Era
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Biomarkers: Definition
• “A specific physical trait or measurable
biologically produced change in the body
connected with a disease or health
condition”
• Any marker of biological status
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Biomarkers: Examples
Biomarker
Hemoccult
Dukes Stage
Serum CEA
Microsatellite
instability
KRAS
Assay
Digital exam
Histology
Blood test
PCR
What it detects
Occult blood
Risk stratification
Recurrent disease
Hereditary cases
Sequencing
Therapeutic response
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Drivers of Biomarker Testing
• Understanding pathogenesis
• Better diagnosis
• Better prognostic information
• Better understanding of therapeutic
response
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Biomarkers in Pathology
• The Past: Diagnosis
• The Recent Past: Simple Prognosis
• The Present
– Advanced Prognosis
– Understanding Biology
• The Future: Therapeutics
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Colon Cancer Diagnostics
• 1700’s: Gross diagnosis
• 1800’s: Microscopic diagnosis
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1. Abdominal mass with
cachexia and bowel
symptoms
2. Abdominal mass and
histologic identification of
tumor
3. Gradual bowel symptoms,
cachexia, stricture
symptoms, and histologic
identification of tumor
Einhorn M, 1900
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Gross Exam (1500-1800)
Microscopic Analysis
(1800-1930)
Electron Microscopy
(1930-1980)
IHC (1980-2000)
DNA
(2000)
Micro
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Biomarkers in Pathology
• The Past: Diagnosis
• The Recent Past: Simple Prognosis
• The Present
– Advanced Prognosis
– Understanding Biology
• The Future: Therapeutics
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Colon Cancer Anatomic Prognosis
• 1932: Dukes Staging System (rectal)
• 1953: Astler-Coller modification of Dukes
• 1965: AJCC Staging System
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Colon Cancer Biology & Prognosis
• 1990-1993: Genetics of familial
adenomatous polyposis (FAP)
– 1991: APC locus identified
– 1993: APC gene cloned
• 1993: Genetics of hereditary nonpolyposis colorectal carcinoma (HNPCC)
– Microsatellite instability identified
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Genetic of Colon Cancer
Tumor
Suppressor
Gene (85%)
15%
5%
Microsatellite
unstable
cases (15%)
HNPCC
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Genetics of Colon Cancer
Tumor
suppressor
gene (APC)
Microsatellite Negative
instability
ImmunoN/A
stains
BRAF
N/A
mutation
hMLH1
N/A
methylation
DNA
mismatch:
hereditary
Positive
DNA
mismatch:
sporadic
Positive
hMSH2 (-)
hMLH1 (-)
Wild-type
Mutant (40%)
Negative
Positive
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Gross Exam (1500-1800)
Microscopic Analysis
(1800-1930)
Electron Microscopy
(1930-1980)
IHC (1980-2000)
DNA
(2000)
Micro
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Biomarkers in Pathology
• The Past: Diagnosis
• The Recent Past: Simple Prognosis
• The Present
– Advanced Prognosis
– Understanding Biology
• The Future: Therapeutics
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Approved Targeted Therapies
Drug
Target of
drug
Trade
name
Tumor
Gefitinib
Erlotinib
Cetuximab
Panitumumab
EGFR
Iressa
Tarceva
Erbitux
Vectibix
Lung
Colon
Trastuzimab
Her2/neu
Herceptin
Breast
Bevacizumab
VEGF
Avastin
Colon
Imatinib
mesylate
Tyrosine
kinase
Gleevec
GIST, CML
Bortezomib
Proteasome
Velcade
Multiple myeloma,
Mantle cell lymphoma
Rituximab
CD20
Rituxan
B cell lymphoma
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Success of Targeted Therapy
Response
Cost
Side Effects
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Cost Per Month
• Gleevec: $3,000
• Herceptin: $2,800
• Rituxan: $12,000
• Iressa: $1,800
75% of$2,700
personal bankruptcy is caused by
• Tarceva:
a catastrophic illness
• Erbitux: $9,600
Himmelstein DU. 24(1),2005
• Vectibix: $8,000
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Future: Biomarkers for Therapeutics
• Selection for therapeutics
– Companion diagnostics
• Monitoring of therapeutic response
– Minimal residual disease testing
• Predicting resistance to therapeutics
– Markers of tumor resistance
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Courtesy of Dr. S. Dacic
EGFR
Extracellular Domain
Transmembrane Domain
TRANSMEMBRANE
Cytoplasmic Domain
PROLIFERATION
APOPTOSIS
ANGIOGENESIS
Epidermal Growth Factor Receptor
• Altered in many tumors
– Protein Expression
– Gene copy number
– Gene sequence
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Epidermal Growth Factor Receptor
• Blockade of EGFR pathway
– Monoclonal antibody
– Small molecule inhibitors of tyrosine kinase
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Monoclonal Ab
(Erbitux)
Small molecule
inhibitors
(Iressa, Tarceva)
Colon Cancer Therapeutics
• 2004: EGFR Pathway in colon cancer
– Erbitux approved by FDA for colon cancer treatment
– EGFR antibody approved by FDA
• 2008: Predictors of resistance
– KRAS mutations insensitivity to Erbitux
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Erbitux Timeline
June, 2008
December, 2001
March, 2009
Early 2005
October, 2007
February, 2004
FDA Approval
• Erbitux
• EGFR PharmDx
FDA negative
report
Literature against
EGFR IHC testing
Completion
of CA225006
ASCO data:
KRAS
Mutation
Anticipated
Completion
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CA225014
Challenges for Pathology
• Biomarker selection
• Testing
– Assay development
– Validation
– Interpretation
Pathologist Training
• Operational impediments
– Patents
– Cost and reimbursement
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Who Validates New Assays?
• Laboratory technical staff
• Anatomic pathologists
• Molecular pathologists
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Predicted Labor Shortage by 2020
350,000
340,000
Number of people
300,000
250,000
Pharmacists
Nurses
Physicians
Med Techs
200,000
150,000
150,000
100,000
50,000
85,000 72,000
0
2020 shortage
Estimated Labor
Shortage by 2020
Auerbach, D. Health Affairs. 26(1), 2007:178
AAMC Study on Physician Shortage, August 2007
Castleberry BM, Lab Med 30, 1999: 174
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Molecular Genetic Pathology Fellowships
80
Programs
Positions
Actual #
Absolute Number
70
60
50
40
39
30
30
20
18
10
8
0
Microbiology
Neuropath
Pediatrics
Source http://www.acgme.org/adspublic/
Accessed March 22, 2008
Molecular
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Who Signs Out Results?
• Send-out laboratories
• Anatomic pathologists
• Molecular pathologists
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AMP Test Directory
• Microsatellite instability: 11 laboratories
• EGFR: 5 laboratories
• K-RAS: 4 laboratories
http://www.amptestdirectory.org/
Accessed 6/2/2008
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Training of Pathologists
Data courtesy of CAP
June, 2008
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Hybrid capture for HPV (1995)
Quantitative PCR (1992)
PCR (1983)
IHC (1978)
Sequencing (1975)
Number of MGP Applicants
70
Absolute Number
60
50
End of
Grandfather
Period
40
30
# Examinees
# Passed
20
10
0
2002
2003
2005
2007
Source: https://www.abpath.org
Accessed 3/23/2008
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Challenges for Pathology
• Biomarker selection
• Testing
– Assay development
– Validation
– Interpretation
• Operational impediments
– Patents
– Cost and reimbursement
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Gross Analysis
Microscopic Analysis
Electron Microscopy
Immunohistochemistry
DNA
Micro
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Auguste Nelaton (1807 – 1873)
(Modified for 2008)
“Biomarker
“The microscope
testing is not, for the biologist or physician,
an instrument which (s)he
he can indifferently make use
of; its employment is absolutely necessary.
the microscopic
appearance,
Accustomed to judge from exterior
characters
alone,
pathologists should not be astonished that many
results obtained by them are shown to be inexact or
incomplete by the microscope.
biomarkers. Far from believing that
the fault comes from the new information added by
biomarkers, it is the history of diseases which
the microscope,
must be taken up again and revised, starting from the
new and much more precise notions of the tissue
furnished by microscopy.”
biomarkers.”
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