Transcript THEORIES SUPPORT FOR CHEMOPREVENTION

Cancer Chemoprevention &
Biomarkers
JianYu Rao, M.D.
Prof. Of Pathology/Epidemiology
UCLA
CANCER PREVENTION
• PRIMARY
• STOP THE EXPOSURE
• SECONDARY
• INTERVENTION
• TERTIARY
• TREATMENT
CANCER INTERVENTION –
Treating premalignant lesions
• Surgical/procedure
• Castration / Oophorectomy
• Polypectomy
• Colposcopy
• Non-surgical (CHEMOPREVENTION)
– Nutritional/chemical
– Immuno (BCG)
– Vaccine
– Molecular targeted
• Behavioral
– Smoking cessation
S Lippman, Cancer Res. 2009 Jul 1;69(13):5269-84
A Most Successful Cancer Control
Story in 20th Century
Pap Test
Colposcopy
+ CONE/LEEP
Detect Early Lesions
Treat Early Lesions
Decreased incidence/
mortality of cervical CA
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
Exposure to Carcinogen
Birth
Precancerous
Intraepithelial
Lesions,
(PIN, CIN, PaIN..)
Additional
Molecular Event
CHEMOPREVENTION
Cancer
Multiyear progression from initiation and early
precancerous lesions to invasive disease in major
cancer target organs
Kelloff et al. 2000 (Fig. 1)
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
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.
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.
Chemoprevention:
Some Terminologies
• INDIVIDUAL RISK AND
STRATIFICATION
• INTERMEDIATE END POINT MARKER
(SURROGATE END POINT MARKER)
• FIELD CANCERIZATION
• MULTI-PATH OF CARCINOGENESIS
RISK STRATIFICATION
• Identification of AT-RISK subjects who are also SUSCEPTIBLE
to treatment:
LEGEND:
Not at risk to develop disease
At risk of developing disease, biology A, responsive to agent X
At risk of developing disease, biology B, NOT responsive to agent X
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
individual’s risk for developing cancer
and to monitor the effectiveness of
intervention methods.
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.
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.
CHEMOPREVENTION IN DIFFERENT
RISK CATEGORIES
Risk category
Parameter
General Population
High Risk
Agent toxicity
Trivial to none
Slight
Selection method
Public Health
Clinical
Other consideration
Use dietary supplements
may be applicable
Need biomarkers
From lee W. Wattenberg, P.S.E.B.M., 1997 216:133-141.
Phase I Trial
Objectives:
• To determine the intervention’s short-term (<1
yr.) dose-toxicity relationship
• To determine the intervention’s human
pharmacokinetics
Design:
•
•
•
•
Single arm, nonrandomized
Multiple dose levels
Less than 1 yr. duration
Accrual 25-100
Phase II Trial
Objectives:
• To determine the intervention’s 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
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
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
CATEGORIES OF
CHEMOPREVENTIVE AGENTS
• BLOCKING CARCINOGEN
METABOLISM AND EXPOSURE
• INCREASE TISSUE
RESISTANCE/DIFFERENTIAITON
• TARGETING ONCOGENIC PATHWAYS
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
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
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)
BRIDGING THE GAP BETWEEN CANCER TREATMENT AND PREVENTION
(William WN, et al, Nat Rev Drug Discov. 2009 Mar;8(3):213-25.)
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
• PCP=18.4% vs 24.8% in treated vs ctrl group
• Selenium/Vit E Trial - negative
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.
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 >50 (for AA) or >55 (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 P>.15) in prostate
cancer end points
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
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.
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
BIOMARKERS OF CANCER
• CLINICAL SETTINGS (TUMOR
MARKERS)
• EPIDEMIOLOGICAL AND PREVENTIVE
SETTINGS (INTERMEDIATE END POINT
OR SURROGATE END POINT
MARKERS).
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
BIOMARKERS
•
•
•
•
Genetic susceptibility markers
Markers of exposure
Markers of biological effects
Tumor markers
Exposure to Carcinogen
Birth
Precancerous
Intraepithelial
Lesions,
(PIN, CIN, PaIN..)e
Additional
Molecular Event
Cancer
Surrogate End Point Markers
Genetic Suscep.
Marker
Markers for
Exposure
Markers of
Effect
CHEMOPREVENTION
Tumor
Markers
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
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)
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 assaypositive cases
• NPV (Negative Predictive Value)
– % of “true” assay-negative cases out of all assaynegative cases
These numbers can be totally meaningless – always know what kind of
design used (case-control vs cohort) and what is the gold standard
OTHER ASSAY ISSUES
• BIOMARKER CAN BE OBTAINED BY NONINVASIVE TECHNIQUES
• ASSAY IS NOT TECHNICALLY DIFFICULT
• MULTIPLE MARKERS CAN BE EVALUATED
SIMULTANEOUSLY IN LIMITED SAMPLE
VOLUMES
• COST
CATEGORIES OF MARKERS
• HISTOLOGICAL AND MORPHOMETRIC
MARKERS
• PROLIFERATION, DIFFERENTIATION
AND INVASION MARKERS
• PATHWAYS SPECIFIC MARKERS
• MARKERS OF GENETIC AND
EPIGENETIC INSTABILITY
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.
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
An example of our 9000 gene mouse-arrays using
differential expression analysis with Cy3 and Cy5
fluorescent dyes.
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
A, GTE (20g/ml)
3.5 4.5 5.1 5.5
6.0
7.0
8.4
pI
9.5 3.5 4.5 5.1 5.5
6.0
7.0
9.53.5 4.5 5.1 5.5
8.4
6.0
7.0
8.4
9.5
MW (kDa)
217
116
98
8
55
2
5
11
37
9
7
10
17
16
6
30
12
9
8
1
1
5
11
13
2
7
10
6
18
16
12
14
15
B, GTE (40g/ml)
3.5 4.5 5.1 5.5
6.0
7.0
8.4
18
14
3
20
13
17
3
15
4
4
pI
9.5 3.5 4.5 5.1 5.5
6.0
7.0
8.4
9.53.5 4.5 5.1 5.5
6.0
7.0
8.4
9.5
MW (kDa)
217
116
98
55
5
1
10
11
12
14
30
1
5
13
17
37
20
19
11
10
18
16
12
14
15
20
15
4
Time:
48 hr
GTE:
-
16
24 hr
48 hr
+
+
17 13
18
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.
Bladder Array
Gelsolin
HE
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
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 targetnegative patients
BIOMARKER STUDY DSEIGN
a. Untargeted Design:
Treatment
Register
Randomize
Control
b. Untargeted Design:
Treatment
Register
Test
Biomarker
Biomarker Randomize
+
Control
BIOMARKER STUDY DSEIGN
Biomarker by Treatment Interaction Design:
Treatment
Biomarker Randomize
+
Control
Register
Test
Stratify
Biomarker
Treatment
Biomarker Randomize
Control
BIOMARKER STUDY DSEIGN
Biomarker Based Strategy Design:
Biomarker
+
Treatment A
Test
Biomarker
Biomarker
-
Treatment B
Register Randomize
No Biomarker
Evaluation
Treatment B
BIOMARKER STUDY DSEIGN
Modified Biomarker Based Strategy Design:
Biomarker
+
Treatment A
Test
Biomarker
Biomarker
-
Treatment B
Register Randomize
Treatment A
No Biomarker Randomize
Evaluation
Treatment B
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
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
Thank You!!!