prostate cancer 101 cell 616
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Prostate Cancer 101 Cell 616. Joshi Alumkal, MD Assistant Professor of Medicine May 6, 2009. Outline. Background on prostate and prostate cancer Androgens and AR Epidemiology Progression model Molecular events Prevention Prostate cancer screening and diagnosis Treatment - PowerPoint PPT PresentationTRANSCRIPT
Prostate Cancer 101Cell 616
Joshi Alumkal, MDAssistant Professor of Medicine
May 6, 2009
Outline• Background on prostate and prostate cancer
– Androgens and AR– Epidemiology– Progression model– Molecular events
• Prevention• Prostate cancer screening and diagnosis• Treatment
– Localized prostate cancer• Prognostication
– Metastatic prostate cancer• Disease states model
– Pre/post hormonal therapy• Is AR still a target after castration?
– Moving beyond hormones to target AR and prostate cancer
Background
Rectal surface
Prostate
Urinary bladder
Rectum
Schematic depiction of the cell types within a human prostatic duct
Abate-Shen C., Shen M. M. Genes Dev. 2000;14:2410-2434
Androgen Receptor -
Androgen Receptor +
Prostate: An androgen-responsive organ
• Prostate develops after puberty due to production of testosterone and more active metabolite dihydrotestosterone, which activate AR, the androgen receptor– AR is a transcription factor which binds to consensus sequences and turns on
target genes such as PSA
• Prostate contributes to fertility by producing enzymes which aid in fertilization of egg
• Testosterone depletion can prevent prostate formation and cancer– Eunuchs do not develop prostates and hence do not get prostate
cancer• Testosterone administration has not been found to cause prostate
cancer in epidemiological studies or animals models– May raise one’s PSA level though and prompt a diagnostic work-up
Active HSP90
HDAC6
AR
Alpha-tubulin
HDAC6
ERG, PSA, and other AR target genes
AR
Ac
Ac
Prostate Cancer Public Health Impact/Demographics
• Prostate cancer is the most common cancer in men– 187,000 new cases estimated for 2008– 50,000 recurrences despite early detection and
treatment• Prostate cancer is also the second most lethal cancer
– 27,050 deaths estimated for 2008• Previously rare in men <50• 1/5 men will be diagnosed in their lifetime
Race and prostate cancer
• African-Americans are at increased risk of prostate cancer development and have more aggressive disease– Even when one accounts for screening and
treatment– Unknown why
• Extremely rare in Asian populations…– Until they move to the U.S.
Diet and Prostate Cancer
• High consumption of broccoli is associated with lower prostate cancer risk– Kristal, Kolonel, Giavanucci– Why?
• High consumption of red meat particularly charred red meat is associated with increased risk– PhIP adducts
• Asians who move to US are at increased risk– Diet?
Viruses and prostate cancer
•Men with mutations in an anti-viral gene called RNase L more likely to have this virus’ cDNA present in their cancer tissue•No causal link demonstrated yet
Nelson, et al NEJM 2003
Different roads to gene silencing
Herman and Baylin NEJM 2003
•DNA methylation•Histone methylation
Genetic + + - Epigenetic - + + = heritable control of gene
expression in the absence of DNA sequence changes
Increase in EZH2
Increase in LSD1
Increase in Sonic hedgehogsignaling
Increase in ERG
Nelson, et al NEJM 2003
ERG and Prostate Cancer• Recent information
suggests that ERG is commonly up-regulated in prostate cancer
• This gene is expressed because it is linked to TMPRSS2, which AR turns on
• ERG over-expression leads to enhanced invasion and increases one risk of cancer recurrence
• The VCaP prostate cancer cell line harbors this translocation
Science 2005
Transgenic ERG mice develop PIN (prostate cancer precursor lesions)
Klezovitch , et al PNAS 2008
Benign PIN
NEJM 2008
Prevention
•Inhibits 5-alpha-reductase enzyme which converts testosterone to more active dihydrotestosterone agonist of AR protein
-Leads to loss of AR function•Similar results presented last week at AUA meeting for related drugdutasteride
Cumulative Incidence of Prostate Cancer Diagnosed in a Biopsy Performed for Cause or after an Interim Procedure
Need to treat 16 men to prevent 1 cancer
Screening/Diagnosis
Prostate cancer screening• PSA is very sensitive and easy to do
– Widely adopted in 1989– Led to surge in new diagnoses
• However,– Many men will be diagnosed with non-life-threatening
cancers with which (rather than of which) they might have died
– Evidence for improvement in survival with treatment is modest NNT=20
• Bill-Axelson, et al NEJM 2005– May be leading to lead-time bias– No high quality RCT has shown a survival benefit
Critical appraisal of screening tests
• Does it do more harm than good?• Specific ?s to ask:
– Is there an RCT that early diagnosis leads to improved survival and/or QOL?
– Are the early diagnosed patients willing partners in the treatment?
– How do benefits/harms compare in screened/unscreened?
– Do the frequency and severity of the target disorder warrant the degree of effort and expenditure?
Number of Diagnoses of All Prostate Cancers (Panel A) and Number of Prostate-Cancer Deaths (Panel B)
•What might explain a negative result in this randomized study of screening?50% of the control arm underwent screening
Schroder F et al. N Engl J Med 2009;10.1056/NEJMoa0810084
Cumulative Risk of Death from Prostate CancerMedian F/U= 9 years
Neverseen a curve likethis
Take homes for screening• Does it do more harm than good?
– Personal matter• Specific ?s to ask:
– Is there an RCT that early diagnosis leads to improved survival and/or QOL?• Yes improved DSS in ERSPC; NNT=48 ; No improved DSS in PLCO• F/U short
– Are the early diagnosed patients willing partners in the treatment?• Yes
– How do benefits/harms compare in screened/unscreened?• Unscreened do not have up-front and persistent harms of screening/treatment liked
screened do• Screened have a marginal reduced risk of death in ERSPC• ? effect on QOL r/e development of symptomatic metastases
– Do the frequency and severity of the target disorder warrant the degree of effort and expenditure?
• Very personal decision• Presently, we do not have a screening test for aggressive prostate cancers
Diagnosis
Prostate gland
Rectum
Definitions
Grade = How well differentiated a tumor isHow closely tumor histologically resembles non-tumor/ normal cells of that organLow-grade = Close resemblanceHigh- grade = Little resemblance
Assign a number to the primary/ predominant pattern.
Assign a 2nd number to the secondary pattern.
The sum of the numbers is the Gleason grade/score.
Gleason grading prostate cancer
Donald G. Gleason (VAMC) 1977
Higher grade,worse prognosis
grade 10 (5+5)
Gleason grading of prostate cancer
Donald G. Gleason (VAMC) 1977
grade 7 (3+4)
Grade (= how closely prostate cancer cells resemble normal prostate glands microscopically)
Pattern 3Gleason grade 3+3=6
Pattern 4Gleason grade 4+4=8
Pattern 5Gleason grade 5+5=10
True, et al PNAS 2006
T . N . M
Incidental (TUR/PSA)
Localized
Locally-advanced
Metastatic
T1A, T1B, T1C
T2A, T2B , T2C
T3A, T3B , T3C
and T4
N(0) vs N(+)M(0) vs M(+)
Stage = Where the tumor is at time of diagnosis
Localized = Tumor is confined to the organ of origin
Regional spread = Tumor has invaded adjacent organs
Metastatic = Discontiguous spread of tumor to other tissues
Take home points
• All men have prostate cancer• The histology (grade) of a prostate cancer is a
basis for selecting the type of treatment• Molecular determinants of grade are specific
biomarkers and targets for therapy
Prostate cancer treatment
Treatment for localized prostate cancer
– Institutional bias determines which modality is given
– Radical prostatectomy– External beam radiation– Equal cure rates for early disease
• No randomized, head-head data comparing these approaches
– Brachytherapy• Most well-studied in low risk tumors
– Androgen-deprivation therapy • Patients who are not candidates for surgery or radiation
– Observation • Patients with very limited life expectancy due to co-
morbid conditions• Patients with very favorable-appearing tumors
Treatment Outcomes in Prostate Cancer
• Overall survival (OS)
• Relapse-free survival (RFS)– PSA blood test is used to monitor relapse– No elevation in PSA or overt disease
recurrence
Radical prostatectomy
• Involves removal of the prostate, adjacent seminal vesicles, and regional lymph nodes
• Can be performed as an open procedure or laparoscopically +/- robotic assistance– No head to data comparing the approaches
• Allows for determination of the pathological extent of disease– Prognostic– May be therapeutic
• Lymph node removal
Radical Prostatectomy Side Effects
• Incontinence
• Impotence– Common post-op but improves with time
• Contrasts with XRT which is less frequent immediately post-treatment but increases with time
– More common in older patients and those with erectile dysfunction pre-op
External Beam Radiation
• Patients are divided into risk groups based upon historical outcomes with XRT
clinical stage PSA Gleason
score
Low risk T1c-T2a <10 6Int risk T2b 10-20 7High risk >T3 >20 8-10
-- D’Amico (1998) JAMA 280:969
External Beam Radiation
• Low risk patients– XRT alone
• Intermediate risk patients– Neoadjuvant Hormonal Therapy->XRT +
Concomitant Hormonal therapy• LHRH-agonist + an anti-androgen
• High risk patients– Neoadjuvant Hormonal Therapy-> XRT +
Concomitant Hormonal Therapy->Adjuvant for a total of 3 years
• LHRH-agonist + an anti-androgen• Bolla, et al ASCO 2007
External Beam Radiation Side Effects
• Acute– Irritative symptoms (rectum and bladder)
• during treatment and afterwards
• Chronic– Impotence
• Lower frequency post-treatment than surgery but increases over time
• More responsive to PDE inhibitors than post-surgical impotence
– Irritative symptoms (rectum and bladder)– Risk of secondary malignancies
Brachytherapy (radioactive seed implantation)
• Reserved for patients with Gleason scores <7 with clinical stage < T2b (tumors on only 1 side of the prostate) and PSA <10
• Follow-up data less mature• Side effects
– Acute– Irritative symptoms (urinary)
– Urinary retention
– Chronic– Impotence
– Irritative symptoms (rectal and urinary)
– Fistulas
– Bleeding
Prognostic pathologic parameters(classic)
• Serum [PSA]• Stage• Grade
Prognosis = Likelihood of the disease recurring after x years
Kattan nomograms
• Useful tool to examine outcome for similar patients to one’s own using wither pre-operative or post-operative data
• Developed from a retrospective database that was externally validated
• Kattan
Multivariable Analysis of the Risk of Biochemical RecurrenceN=151
Covariate Odds ratio 95% CI* P value
Preoperative PSA 1.00 0.91 – 1.09 0.99
Postoperative Gleason score 3.77 1.87 – 7.62 0.0002
Extra capsular penetration 4.92 1.31 – 18.52 0.02
Lymph node involvement 7.26 0.92 – 57.59 0.06
Seminal vesicle involvement 13.41 1.76 – 101.84 0.01
Surgical margin involvement 7.73 1.90 – 31.46 0.004
CDKN2A methylation 0.43 0.10 – 1.90 0.27
GSTP1 methylation 0.30 0.07 – 1.24 0.10
ASC methylation 2.08 0.57 – 7.60 0.27
CDH13 methylation 5.51 1.34 – 22.67 0.02
RUNX3 methylation 0.60 0.16 – 2.28 0.45
MGMT methylation 0.33 0.07 – 1.63 0.17
* Preoperative PSA and postoperative Gleason score were treated as continuous variables
#CI: Confidence intervalAlumkal, et al 2008
Disease States Model of Prostate Cancer
LocalizedPSA RelapseHormone-naive
MetastaticHormone-naive
PSA RelapseCastrate
MetastaticCastrate Metastatic
CastrateDocetaxel-resistant
Death
Lung
BoneLiver
Epidural space
Lymphnodes
Metastatic Disease
What is happening in the tumor in a metastasis
• We do not fully know• Clinical trials at OHSU
– Bone biopsy prior to starting therapy to examine tumors with microarrays
– Stratify to specific treatment based upon genes– Correlate with response/resistance to treatment– Allow for better identification of genes responsible for
sensitivity/resistance to treatments
Treating metastases• Goals are relief of symptoms and prolongation
of survival– Pain-control is crucial– Using most effective and least toxic treatments up-front– Sequencing treatments
Prostatic acid phosphatase
Alkaline phosphatase
Testosterone(T)/Dihydrotestosterone(DHT)
ARE PSA ARE PSA
AR AR
AR and Androgens in Prostate Cancer
Pre-castrate Castrate-resistant (no longer called “androgen independent”)
Mutated AR
Lower but not absent T/DHT
Hormonal therapy is our most effective treatment
• LHRH-agonists– Over stimulate hypothalamus -> decreased LHRH-> decreased LH-> decreased testosterone– Initially, these treatments increase testosterone– 80-90% PSA response rate– Most patients also have objective RRs– Median duration response 18-24 months
• Anti-androgens– Compete with testosterone, DHT for binding to AR– 30-40% PSA response rate– Median duration response 6-12 months– Anti-androgen withdrawal response
• 25% of men progressing on an anti-androgen will have a PSA response and palliation of systems for 4-6 months when anti-androgen is D/C’d
• Felt to be due to AR mutations, which cause these drugs to act as agonists• Ketoconazole
– Inhibits both gonadal and adrenal steroidogenesis– 20% RR– Median duration response 6-8 months
LHRH agonists,DES
Orchiectomy
Targeting the Androgen Receptor (AR) Protein
• AR is the engine of prostate cancer– Activated by testosterone, the fuel of prostate cancer– PSA is a gene which goes up when the engine is on– ERG is a gene which can promote prostate cancer
development and invasion, which goes up when the engine is on
• The wheels of prostate cancer
• Hormonal treatments inhibit prostate cancer mainly by reducing levels of testosterone (fuel)
• Prostate cancer cells can eventually grow despite low levels of testosterone (fuel)
• We then try to dilute out the remaining fuel with “water,” drugs called anti-androgens
Hormonal Treatments
Growth and spreaddespite low levels of testosterone (fuel)
X
Death of some cancer cells
“Water down” the gas further
Chemotherapy
Supportive Care
• Bone health– Adequate calcium and Vit D to prevent osteoporosis
from hormonal treatments– Bisphosphonates
• Inhibit osteoclast function• When given to men who have castrate-resistant metastatic
cancers, this helps prevent fractures
• Pain control– XRT– Analgesics
Is AR still a target when hormonal therapy fails: “androgen
independence” versus “castration resistance”?
Nature Medicine 2004
Cancer Research 2007
New therapies targeting AR after castration resistance appear active • MDV3100
• Abiraterone acetate– Reduces adrenal steroidogenesis
Tran, et al Science 2009
Looking beyond hormonal therapy to target AR and prostate cancer:
our approach
Diet, sulforaphane, and prostate cancer
• There is strong epidemiological evidence for an inverse risk of prostate cancer development and high intake of cruciferous vegetables, namely broccoli• Cohen, et al 2000, Kolonel, et al 2000, Giovannucci, et al 2003
• Nonetheless, many people do not consume these foods frequently• Sulforaphane
– Broccoli constituent – Prevents/delays tumor formation in murine models of colon cancer, other
tumors– Fahey, et al 1997, Chung, et al 2000, Shen, et al 2007
– Causes cancer cell death or tumor regression in vitro and in prostate cancer xenografts
– Mechanisms?• Induction of Phase 2 detoxification enzymes, apoptosis, cell cycle arrest
• Zhang 2004• Histone deacetylase inhibition
• Myzak, et al 2004
N - K - C
AC
HATs HDACs
SIGNALING
Histone proteins Non-histone proteins (HSP90, Tubulin)
Chromatin remodeling
Gene expression
Stability (AR, Her2Neu, Bcr-Abl, etc)
slide courtesy of David Qian
Centrality of AR in prostate cancer• Expressed in nearly all human prostate cancers• Key target for prevention and therapy
– Finasteride, LHRH-agonists, anti-androgens, lyase inhibitors, etc• Resistance to these therapies is common
– AR mutations– Intratumoral androgens persist despite effective serum castration (Mostaghel,
et al 2007)– Depletion of AR protein is a way to overcome these modes of resistance
• Certain pharmacological HDAC inhibitors lower AR protein levels through HDAC6 inhibition and loss of HSP90 function
• Bali, et al 2005, Scroggins, et al 2007
• Hypothesis– We hypothesized that sulforaphane treatment would lead to hyperacetylation
of HSP90 and that this would destabilize AR protein and attenuate AR signaling.
• i.e. We hypothesized we could take out the engine block!
Gibbs, et al PNAS in revision
Taking out the whole engine block (and the wheels) rather than just the
fuel
Gibbs, et al PNAS in revision
Gibbs, et al PNAS in revision
Sulforaphane
Decreased de-acetylationof HSP90 and alpha-tubulin
Protein instability and proteasomal degradation of AR and HDAC6
Hyperacetylated, inactive HSP90Active HSP90
HDAC6
Inactive or reducedlevels of HDAC6XAR
XXAR
Hyperacetylated alpha-tubulin- ? role
Alpha-tubulin
Acetyl
HDAC6
X
Inactive or reduced levels of HDAC6
ERG and other AR target genesERG and other AR target genes
AR
X XHDAC6
Gibbs, et al PNAS in revision
What we know/don’t know• ERG over-expression leads to PIN precursor lesions in
transgenic mice and cellular invasiveness • 35% of human PIN lesions express ERG• Most prostate cancers express ERG• Diets high in broccoli are associated with a reduced risk
of prostate cancer– Sulforaphane, in broccoli, shuts down AR and ERG (and other AR
target genes like PSA) expression• Will this prevent prostate cancer precursor lesions through this
mechanism?• Will this lower PSA levels and have anti-cancer properties in men with
recurrent prostate cancer?
To determine whether SFN supplementation in a murine PIN model of prostate cancer leads to disruption of AR and ERG expression and
reduced incidence of PIN formation.
Klezovitch PNAS 2008
Benign PIN (Prostate cancer precursor)
ERG
SFN
X?
Current Directions with Sulforaphane
• Feeding ERG transgenic mice sulforaphane to see if we can prevent prostate cancer
• Clinical trial with sulforaphane in men whose cancers recur despite aggressive treatments like surgery or radiation
• Further explore the effect of sulforaphane on prostate cancer cells
Specific gene regulation requires the assembly and coordinate action of demethylases with distinct substrate specificities
PSA
LSD1
JHDM2A
JMJD2C
AR
Other chromatin modification factors??
Non-castrate:
PSA
Other chromatin modification factors??
Castrate State:
ON
REDUCED (NOT OFF)
Metzger, et al Nature 2005Yamane, et al Cell 2006Wissman, et al Nature Cell Bio 2007
LSD1
JMJD2C
AR
LSD1• LSD1 (Lysine specific demethylase
1) – A monoamine oxidase– Silences genes with HDACs, which are
commonly up-regulated in prostate cancer
• Shi, et al 2004– Found to complex with AR protein and
turn on AR target genes• Metzger, et al 2005• Yamane, et al 2006
– Higher LSD1 levels or low levels of the histone mark it removes are associated with prostate cancer recurrence
• Kahl, et al 2006• Seligson, et al 2006
– Inhibition or knock-down of LSD1 leads to reduced cell growth
• Which LSD1 gene targets mediate this??
Turns off genes
Turns on genes
Wysocka, et al 2005
1c Treatment Reduces PSA
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
Mock in Presence ofTestosterone
1c in Presence ofTestosterone
Mock in Absence ofTestosterone
1c in Absence ofTestosterone
SAMPLE
EX
PR
ES
SIO
N
Treatment with a LSD1 small molecule inhibitor reduces PSA
ChIP PCR of PSA gene
QRTPCR of PSA gene
Check human prostate cancer samples to determine genes whose
expression is directly/inversely correlated
with LSD1 by expression arrays
Expression arrays after siLSD1 and pharmacological inhibitor treatment
in vitro-293 common genes increase-51 common genes decrease
Check LSD1 ChIP-Chip datasets for genes with LSD1 enrichment
Putative direct, functional LSD1 targets-Assess LSD1 occupancy, control of expression-Assess gene role in transformation
Modified fromYu, et al 2007
Vehicle LSD1 inhibitorsiNTC siLSD1
Summary• Prostate cancer is common, detectable, sometimes lethal• Targeting AR may prevent cancer
– Diet?• Screening can ID cancers
– Need better methods to screen for aggressive cancers
• Variety of treatment options for localized disease– Path features and molecular basis for these features may aid in
prognostication
• AR is a key target for treatment in all phases of the disease (even after castration resistance)
• Translational, molecular studies hold promise for improving patient outcomes
Acknowledgements• Alumkal lab
– Angela Gibbs– Jacob Schwartzman– Dylan Zodrow– Lina Gao, PhD– Looking for another good post-doc!
• Fred Hutchinson– Larry True
• Johns Hopkins– James Herman– Robert Casero
• Wayne State– Pat Wooster