Cancer Chemoprevention

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Cancer Chemoprevention Biomarkers

• JianYu Rao, M.D.
• Prof. Of Pathology/Epidemiology
• UCLA

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CANCER PREVENTION

• PRIMARY
• STOP THE EXPOSURE
• SECONDARY
• INTERVENTION
• TERTIARY
• TREATMENT

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CANCER INTERVENTION Treating premalignant
lesions

• Surgical/procedure
• Castration / Oophorectomy
• Polypectomy
• Colposcopy
• Non-surgical (CHEMOPREVENTION)
• Nutritional/chemical
• Immuno (BCG)
• Vaccine
• Molecular targeted
• Behavioral
• Smoking cessation

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S Lippman, Cancer Res. 2009 Jul 169(13)5269-84
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A Most Successful Cancer Control Story in 20th
Century
Colposcopy CONE/LEEP
Pap Test
Detect Early Lesions
Treat Early Lesions
Decreased incidence/ mortality of cervical CA
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CHEMOPREVENTION

• Administrating specific amounts of a particular
  natural or synthetic chemical in an attempt to
  identify agents that will prevent, halt or
  reverse the process of carcinogenesis
• The basic assumption is that treating early
  stages of malignant process will halt the
  progression of malignancy
• The key is to define early lesions, and treat the
  malignant field

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Additional Molecular Event
Exposure to Carcinogen
Precancerous Intraepithelial Lesions, (PIN,
CIN, PaIN..)
Cancer
Birth
CHEMOPREVENTION
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Multiyear progression from initiation and early
precancerous lesions to invasive disease in major
cancer target organs
Kelloff et al. 2000 (Fig. 1)
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THEORIES SUPPORT FOR CHEMOPREVENTION

• EPIDEMIOLOGICAL EVIDENCE
• OVER 50 CANCERS HAVE NO KNOWN RISK FACTORS
• NUMEROUS EVIDENCE TO DEMONSTRATE THE INVERSE
  RELATIONSHIPS OF SOME NUTRIENT FACTORS WITH
  CANCER RISKS

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THEORIES SUPPORT FOR CHEMOPREVENTION (Cont.)

• EXPERIMENTAL EVIDENCE
• ALTHOUGH CARCINOGENESIS IS REGARDED AS
  NONREVERSIBLE PROCESS, STUDIES SHOWED THIS IS
  ONLY TRUE AT LATE STAGE. IN FACT, A LARGE
  PORTION OF THE LONG LATENCY PERIOD OF
  CARCINOGENIC PROCESS IS REVERSIBLE.
• IN VITRO CULTURE AND IN VIVO ANIMAL STUDIES
  IDENTIFIED NUMEROUS AGENTS THAT CAN REVERSE, OR
  HALT THE CARCINOGENESIS PROCESS, PARTICULARLY AT
  THE EARLY STAGE.

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THEORIES SUPPORT FOR CHEMOPREVENTION (Cont.)

• CLINICALLY
• ADVANCES IN CERTAIN TYPES OF CANCER TREATMENT
  HAVE LIMITED SUCCESS IN REDUCING THE OVERALL
  INCIDENCE, OR EVEN MORTALITY OF CANCER.

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ChemopreventionSome Terminologies

• INDIVIDUAL RISK AND STRATIFICATION
• INTERMEDIATE END POINT MARKER (SURROGATE END
  POINT MARKER)
• FIELD CANCERIZATION
• MULTI-PATH OF CARCINOGENESIS

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RISK STRATIFICATION

• Identification of AT-RISK subjects who are also
  SUSCEPTIBLE to treatment

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INTERMEDIATE END POINT MARKER (SURROGATE END
POINT MARKER)

• These are prevention biomarkers which are
  specifically related to early stages of
  carcinogenesis.
• These markers are used to identify individuals
  risk for developing cancer and to monitor the
  effectiveness of intervention methods.

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FIELD CANCERIZATION

• The whole field of tissue of a particular organ
  is exposed to the carcinogenic insult and is at
  increased risk for developing cancer.
• Although only a few foci eventually develop
  malignancy, the other areas are not necessary
  entirely normal.
• Most common epithelia cancers are developed
  through this mechanism. Examples of such cancers
  are Head and neck ca, bladder ca, breast ca,
  lung ca, GI ca, etc.

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MULTI-PATH OF CARCINOGENESIS

• The current model of carcinogenesis is that
  cancer develops through multiple events which are
  not necessary through linear steps, but rather
  through overlapping networks.

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CHEMOPREVENTION IN DIFFERENT RISK CATEGORIES
Risk category
Parameter
General Population High Risk
Agent toxicity Trivial to none Slight Selectio
n method Public Health Clinical Other
consideration Use dietary supplements Need
biomarkers may be applicable
From lee W. Wattenberg, P.S.E.B.M., 1997
216133-141.
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Phase I Trial

• Objectives
• To determine the interventions short-term (lt1
  yr.) dose-toxicity relationship
• To determine the interventions human
  pharmacokinetics
• Design
• Single arm, nonrandomized
• Multiple dose levels
• Less than 1 yr. duration
• Accrual 25-100

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Phase II Trial

• Objectives
• To determine the interventions side effects
• To determine optimal recruitment methods of the
  target population
• To determine retention of study participants to
  the study intervention and procedures
• To determine optimal methods for the conducting
  of a phase III trial
• To determine the effect of the intervention on
  biomarkers of carcinogenesis (phase II b)
• Design
• Randomized, double-blind, placebo-controlled
• Multiple dose levels or agents
• One to five years in duration
• Accrual 100s-1000s

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Phase III Trial

• Objectives
• To determine the effect of the intervention on
  the cancer incidence (total and specific cancer
  type)
• To determine the effect of the intervention on
  death rate and disease incidence
• To determine the long-term side effects of the
  intervention
• To determine the nature history of specific
  biomarkers of carcinogenesis (placebo group) and
  the effect of the intervention agent (treatment
  group) on these markers.
• Design
• Randomized, double-blind, placebo-controlled
• Multiple dose levels or agents, alone or in
  combination
• Five to ten years in duration
• Accrual 1000s-10,000s

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UNIQUE FEATURES OF CHEMOPREVENTION

• Participants are usually healthy or at least
  cancer free
• The degree and incidence of side effects that are
  acceptable are low
• The end point is disease prevention, not disease
  response
• The incidence of the study end point is low

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CATEGORIES OF CHEMOPREVENTIVE AGENTS

• BLOCKING CARCINOGEN METABOLISM AND EXPOSURE
• INCREASE TISSUE RESISTANCE/DIFFERENTIAITON
• TARGETING ONCOGENIC PATHWAYS

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CATEGORIES OF CHEMOPREVENTIVE AGENTS

• BLOCKING AGENTS
• Prevent metabolic activation of carcinogens or
  tumor promoters
• Enhance detoxification
• Glutathione-S-transferase
• Trap reactive carcinogenic species
• Glutathione, N-Acetylcysteine
• Vaccines HBV, HPV

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CATEGORIES OF CHEMOPREVENTIVE AGENTS (Cont.)

• INCREASING TISSUE RESISTANCE
• Induce tissue maturation/differentiation
• Pregnancy or hormonal induced maturation of
  terminal ducts of breast - decrease breast cancer
• Retinoids, DMFO, etc
• Decrease target tissue function
• Castration - reduce risk of prostate ca
• Decrease cell proliferation
• Low fat diet decrease epithelial proliferation
  rate in intestinal tract - reduce colon cancer
  risk

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CATEGORIES OF CHEMOPREVENTIVE AGENTS (Cont.)

• PATHWAY SPECIFIC AGENTS
• Cox-2 inhibitors
• Anti-angiogenesis
• Anti-EGFR
• Hormone antagonists
• Augmenting tumor suppressor functions
• Inhibiting oncogenic activities (e.g., Ras)

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BRIDGING THE GAP BETWEEN CANCER TREATMENT AND
PREVENTION (William WN, et al, Nat Rev Drug
Discov. 2009 Mar8(3)213-25.)
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CHEMOPREVENTION TO HUMANS - UPDATE

• BREAST CANCER
• Selective Estrogen Receptor Modulator (SERM)/STAR
  Trial
• Animal model well established
• PROSTATE CANCER
• SCID model established
• Hormonal modulation may have potential
• PCPT Trial Finasteride (5-a-reductase, 5mg/day)
• 2-arm trial, 18,882 subjects, 7 yrs
• PCP18.4 vs 24.8 in treated vs ctrl group
• Selenium/Vit E Trial - negative

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STAR TRIAL

• STAR The Study of Tamoxifen (20 mg/day) and
  Raloxifene (60 mg/day) for breast cancer
  prevention
• A Phase III trial involving over 50 centers and
  19,747 high risk women age 35 or above
• Both drugs reduced the risk of developing
  invasive breast cancer by about 50 percent.
• In addition, women who took raloxifene daily had
  36 percent fewer uterine cancers and 29 percent
  fewer blood clots than the women who took
  tamoxifen.

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SELECT TRIAL (Lippman, et al, JAMA, 2009)

• SELECT Selenium and Vitamin E Cancer Prevention
  Trial
• A Phase III trial involving over 400 sites and
  35533 men, age gt50 (for AA) or gt55 (others)
• 4 groups (selenium, vitamin E, selenium vitamin
  E, and placebo) in a double-blind fashion between
  August 22, 2001, and June 24, 2004
• No significant differences (all Pgt.15) in
  prostate cancer end points

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CHEMOPREVENTION TO HUMANS - UPDATE (CONT.)

• GASTRIC AND ESOPHAGEAL CANCER
• A combination of beta carotene, vitamin E, and
  selenium may be effective in early stage lesions,
  but not late severe dysplastic lesions.
• LUNG CANCER
• Beta-carotene or alpha-tocopherol showed reverse
  effect in lung cancer risk in heavy smokers in
  Finland
• Ongoing trials with COX-2 inhibitor in former
  smokers here at UCLA

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CHEMOPREVENTION TO HUMANS - UPDATE (CONT.)

• COLON CANCER
• Sulindac, a nonsteroidal anti-inflammatory
  compound hold great promise. Others, such as
  Oltiparz, selenium, and antioxidants vit. E/A,
  etc, may also be effective. Large trials are not
  available.
• HEAD AND NECK CANCER
• Retinoids showed promising results in both animal
  models and human studies.

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SUMMARY (CHEMOPREVENTION)

• Chemoprevention is an important approach for
  cancer control
• The goal is to treat premalignant lesions
• Successful stories include cervix, breast,
  prostate, head and neck
• Less successful stories include lung, colon, etc
• No magic single bullet, but new molecular
  targets show greater promise than traditional
  nutritional regimens

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BIOMARKERS OF CANCER

• CLINICAL SETTINGS (TUMOR MARKERS)
• EPIDEMIOLOGICAL AND PREVENTIVE SETTINGS
  (INTERMEDIATE END POINT OR SURROGATE END POINT
  MARKERS).

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CURRENT CLINICALLY USED TUMOR MARKERS

• PSA - Prostate Adenocarcinoma
• Alpha FP - Hepatoma seminoma
• HCG - Choriocarcinoma
• CEA - Colon cancer
• CA19.9 Pancreatic cancer
• CA125 Ovarian cancer
• Problem Low sensitivity/specificity

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BIOMARKERS

• Genetic susceptibility markers
• Markers of exposure
• Markers of biological effects
• Tumor markers

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Additional Molecular Event
Exposure to Carcinogen
Precancerous Intraepithelial Lesions, (PIN,
CIN, PaIN..)e
Cancer
Birth
Surrogate End Point Markers
Markers for Exposure
Markers of Effect
Tumor Markers
Genetic Suscep. Marker
CHEMOPREVENTION
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HOW TUMOR MARKERS ARE USED CLINICALLY

• Early detection and diagnosis
• Predict the biological potential of cancer
  (prognostication)
• Determine who will be likely benefited from the
  therapy (phamacocogenetic / pharmacogenomic)
• Monitor the effectiveness of therapy

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CRITERIA FOR SELECTING BIOMARKER

• FITS EXPECTED BIOLOGICAL MECHANISM
• BIOMARKER AND ASSAY PROVIDE ACCEPTABLE
  SENSITIVITY, SPECIFICITY, AND ACCURACY
• BIOMARKER IS EASILY MEASURED
• BIOMARKER MODULATION CORRELATES TO THE END POINT
• Disease incidence (for detection marker)
• Disease progression (for prognostic marker)
• Response to therapy (for therapeutic marker)

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ASSAY VALIDITY

• SENSITIVITY
• of assay-positive cases in case group
• SPECIFICITY
• of assay-negative cases in control group
• PPV (Positive Predictive Value)
• of true assay-positive cases out of all
  assay-positive cases
• NPV (Negative Predictive Value)
• of true assay-negative cases out of all
  assay-negative cases

These numbers can be totally meaningless always
know what kind of design used (case-control vs
cohort) and what is the gold standard
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OTHER ASSAY ISSUES

• BIOMARKER CAN BE OBTAINED BY NON-INVASIVE
  TECHNIQUES
• ASSAY IS NOT TECHNICALLY DIFFICULT
• MULTIPLE MARKERS CAN BE EVALUATED SIMULTANEOUSLY
  IN LIMITED SAMPLE VOLUMES
• COST

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CATEGORIES OF MARKERS

• HISTOLOGICAL AND MORPHOMETRIC MARKERS
• PROLIFERATION, DIFFERENTIATION AND INVASION
  MARKERS
• PATHWAYS SPECIFIC MARKERS
• MARKERS OF GENETIC AND EPIGENETIC INSTABILITY

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Issues in Using Biomarker

• The observed change may not correlate with end
  point (cancer incidence, response to therapy,
  etc).
• Can not measure the quality of life.
• Adverse effect may not be observed in short term
  biomarker studies.

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High Throughput Techniques

• Array technology (-omics)
• DNA chips
• cDNA array format
• in situ synthesized oligonucleotide format
  (Affymetrix)
• Proteomics
• Tissue arrays
• These are powerful tools and high throughput
  methods to fish-out biomarker targets, but they
  are not the answers themselves
• Individual targets/patterns identified need to be
  validated

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Proteomics

• Examine protein level expression in a high
  throughput manner
• Used to identify protein markers/patterns
  associated with disease/function
• Different formats
• SELDI-TOF (laser desorption ionization
  time-of-flight) the protein-chip arrays, the
  mass analyzer, and the data-analysis software
• 2D Page coupled with MALDI-TOF (matrix-assisted
  laser desorption ionization time-of-flight)
• Antibody based formats

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A, GTE (20?g/ml)
pI
9
MW (kDa)
8
8
9
2
2
1
1
5
5
11
10
11
13
13
10
7
17
6
7
6
17
18
16
16
18
12
12
14
14
3
3
15
15
4
4
B, GTE (40?g/ml)
pI
20
19
MW (kDa)
1
1
5
10
5
11
11
13
17
17
13
10
18
12
18
16
16
12
14
14
15
15
4
Time
48 hr
48 hr
24 hr
-


GTE
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Tissue Array

• Provide a new high-throughput tool for the study
  of gene dosage and protein expression patterns in
  a large number of individual tissues for rapid
  and comprehensive molecular profiling of cancer
  and other diseases, without exhausting limited
  tissue resources.
• A typical example of a tissue array application
  is in searching for oncogenes amplifications in
  vast tumor tissue panels. Large-scale studies
  involving tumors encompassing differing stages
  and grades of disease are necessary to more
  efficiently validate putative markers and
  ultimately correlate genotypes with phenotypes.
• Also applicable to any medical research
  discipline in which paraffin-embedded tissues are
  utilized, including structural, developmental,
  and metabolic studies.

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Bladder Array
Gelsolin
HE
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Lessons learned from SELDI-TOF

• Initial study on patient serum from cancer
  patients (ovarian, prostate, etc) versus cancer
  showed very promising results (nearly 100
  sensitivity/specificity to separate cancer from
  normal)
• Used case-control design
• Only 2 group-comparison (cancer vs. normal)
• No validation
• However, recent validation studies were rather
  disappointing

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Biomarker-Directed Targeted Design

• Increase the efficiency of the trial, but
  depends on
• The performance of the biomarker test
  (sensitivity/specificity)
• Size of the treatment effect for target-negative
  patients

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BIOMARKER STUDY DSEIGN
a. Untargeted Design
Treatment
Register
Randomize
Control
b. Untargeted Design
Treatment
Biomarker
Test Biomarker
Randomize
Register
Control
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BIOMARKER STUDY DSEIGN
Biomarker by Treatment Interaction Design
Treatment
Biomarker
Randomize
Control
Test Biomarker
Stratify
Register
Treatment
Biomarker -
Randomize
Control
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BIOMARKER STUDY DSEIGN
Biomarker Based Strategy Design
Biomarker
Treatment A
Test Biomarker
Biomarker -
Treatment B
Register
Randomize
No Biomarker Evaluation
Treatment B
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BIOMARKER STUDY DSEIGN
Modified Biomarker Based Strategy Design
Biomarker
Treatment A
Test Biomarker
Biomarker -
Treatment B
Register
Randomize
Treatment A
No Biomarker Evaluation
Randomize
Treatment B
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GENETIC SUSCEPTIBILITY MARKERS

• Genome Wide Association (GWA) studies help to
  identified genetic markers for cancer
• Prostate Chromosome 8q24 (Gudundsson, et al,
  Nature genetics/Yeager, et al, Nature Genetics,
  2007)
• Lung Chromosome 15q25 (nicotinic acetylcholine
  receptor subunits) (Huang, et al, Nature
  2008/Amos, et al, Nature Genetics,
  2008/Thorgerisson, et al, Nature genetic, 2008)
• Genes identified in these locus may also be the
  targets for chemopreventive drug development

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SUMMARY

• No magic single marker, or a pattern of marker,
  that will address all issues about cancer
• Know exactly what the marker is used for, and the
  criteria/gold standard for marker may be
  different
• Early detection - precancer lesion
• Diagnosis - cancer
• Therapeutic selection/monitoring - response
• Prognostic indication - progression
• -omics is a useful commodity to find marker.
  However, more simplified method should be used to
  detect marker clinically

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Thank You!!!