biomarkers in anatomic pathology adding value in diagnostics jennifer hunt, md, med, fcap

Biomarkers in Anatomic PathologyAdding 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 PathologyDirector, Head and Neck and Endocrine PathologyDirector, Molecular Anatomic Pathology Unit

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“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.”

Auguste Nélaton (1807 – 1873)

1600 1700 1800 1900

Zaccharias Janssen (1590-1608): First Microscope

Anton van Leeuwenhoek (1632-1723): Bacteria

Rudolph Virchow (1821-1902): Father of Microscopic Pathology

Carl Rokitansky (1804-1878): Father of Autopsy Pathology

Robert Hooke (1635-1703) Father of Microscopy

1950 1960 1970 1980 1990 2000

Kary Mullis (1983): Polymerase Chain Reaction (Nobel Prize, 1993)

Watson & Crick (1953): DNA (Nobel Prize, 1962)

Alfred Knudson (1971): Tumor suppressor genes (Lasker Award, 1998)

Sternberger (1978): Immuno-cytochemistry

Ernst Ruska & Max Knott (1931): Electron Microscope (Nobel Prize, 1986)

Peyton Rous (1910): Oncogenes (Nobel Prize 1966)

Frederick Sanger (1975): Sequencing (Nobel Prize, 1980)

Gross Exam (1500-1800)

Microscopic Analysis (1800-1930)

Electron Microscopy (1930-1980)

IHC (1980-2000)

DNA (2000)

MicroRNA

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1800DiagnosticAssay Era

Agenda: Biomarkers in AP

•The Past: Diagnosis

•The Present: Prognosis

•The Future: Therapeutics

1960PrognosticAssay Era

2000TherapeuticAssay 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 Assay What it detects

Hemoccult Digital exam Occult blood

Dukes Stage Histology Risk stratification

Serum CEA Blood test Recurrent disease

Microsatellite instability

PCR Hereditary cases

KRAS 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)

MicroRNA

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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 non-polyposis colorectal carcinoma (HNPCC)–Microsatellite instability identified

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Genetic of Colon Cancer

15%

Tumor SuppressorGene (85%)

HNPCC5%

Microsatellite unstable cases (15%)

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Genetics of Colon Cancer

Tumor suppressor gene (APC)

DNA mismatch: hereditary

DNA mismatch: sporadic

Microsatellite instability

Negative Positive Positive

Immuno-stains

N/A hMSH2 (-) hMLH1 (-)

BRAF mutation

N/A Wild-type Mutant (40%)

hMLH1 methylation

N/A Negative Positive

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Gross Exam (1500-1800)

Microscopic Analysis (1800-1930)

Electron Microscopy (1930-1980)

IHC (1980-2000)

DNA (2000)

MicroRNA

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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 CostSide Effects

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Cost Per Month

•Gleevec: $3,000

•Herceptin: $2,800

•Rituxan: $12,000

• Iressa: $1,800

•Tarceva: $2,700

•Erbitux: $9,600

•Vectibix: $8,000

75% of personal bankruptcy is caused by a catastrophic illness

Himmelstein DU. 24(1),2005

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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

TRANSMEMBRANECELL

MEMBRANE

ANGIOGENESISPROLIFERATION APOPTOSIS

Extracellular Domain

Cytoplasmic Domain

Transmembrane Domain

EGFRCourtesy of Dr. S. Dacic

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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

Monoclonal Ab(Erbitux)

Small moleculeinhibitors

(Iressa, Tarceva)

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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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October, 2007

Completion of CA225006

Erbitux Timeline

March, 2009

Anticipated Completion

of CA225014

Early 2005

Literature againstEGFR IHC testing

February, 2004

FDA Approval• Erbitux• EGFR PharmDx

December, 2001

FDA negative report

June, 2008

ASCO data: KRAS

Mutation

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Challenges for Pathology

•Biomarker selection

•Testing–Assay development

–Validation

– Interpretation

•Operational impediments–Patents

–Cost and reimbursement

Pathologist Training

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Who Validates New Assays?

•Laboratory technical staff

•Anatomic pathologists

•Molecular pathologists

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Predicted Labor Shortage by 2020

150,000

340,000

85,000 72,000

0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

2020 shortage

Pharmacists

Nurses

Physicians

Med Techs

Nu

mb

er o

f p

eop

le

Estimated Labor Shortage by 2020 Auerbach, D. Health Affairs. 26(1), 2007:178AAMC Study on Physician Shortage, August 2007Castleberry BM, Lab Med 30, 1999: 174

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Molecular Genetic Pathology Fellowships

Source http://www.acgme.org/adspublic/Accessed March 22, 2008

Ab

solu

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ber

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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 CAPJune, 2008

PCR (1983)

IHC (1978)

Sequencing (1975)

Hybrid capture for HPV (1995)

Quantitative PCR (1992)

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Number of MGP Applicants

0

10

20

30

40

50

60

70

2002 2003 2005 2007

# Examinees

# Passed

Source: https://www.abpath.orgAccessed 3/23/2008

End of Grand-fatherPeriod

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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

Immunohisto-chemistry

DNA

MicroRNA

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“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.”

Auguste Nelaton (1807 – 1873)(Modified for 2008)

“Biomarker testing

biomarkers.

the microscopic appearance,

(s)he

biomarkers,

biomarkers.”

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