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