Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
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 – 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 Urinary bladder Prostate Rectal surface Rectum Schematic depiction of the cell types within a human prostatic duct Androgen Receptor - Androgen Receptor + Abate-Shen C., Shen M. M. Genes Dev. 2000;14:2410-2434 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 AR Active HSP90 HDAC6 Ac HDAC6 Ac Alpha-tubulin AR ERG, PSA, and other AR target genes 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 Genetic Epigenetic + - + + + = heritable control of gene expression in the absence of DNA sequence changes •DNA methylation •Histone methylation Herman and Baylin NEJM 2003 Increase in ERG Increase in EZH2 Increase in LSD1 Increase in Sonic hedgehog signaling Nelson, et al NEJM 2003 ERG and Prostate Cancer • Recent information suggests that ERG is commonly upregulated 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) Benign PIN Klezovitch , et al PNAS 2008 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 drug dutasteride 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 Percent of men Prevalance of cancer (at autopsy) Wayne State Univ: Dr. Wael Sakr 80 70 60 50 40 30 20 10 0 All m 20-29 30-29 40-49 50-59 60-69 70-79 Age (by decade) 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 Cumulative Risk of Death from Prostate Cancer Median F/U= 9 years Never seen a curve like this Schroder F et al. N Engl J Med 2009;10.1056/NEJMoa0810084 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 is How closely tumor histologically resembles non-tumor/ normal cells of that organ Low-grade = Close resemblance High- grade = Little resemblance Gleason grading prostate cancer 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. Donald G. Gleason (VAMC) 1977 Gleason grading of prostate cancer Higher grade, worse prognosis grade 7 (3+4) grade 10 (5+5) Donald G. Gleason (VAMC) 1977 Grade (= how closely prostate cancer cells resemble normal prostate glands microscopically) Pattern 3 Gleason grade 3+3=6 Pattern 4 Pattern 5 Gleason grade 4+4=8 Gleason grade 5+5=10 True, et al PNAS 2006 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 T.N.M Incidental (TUR/PSA) T1A, T1B, T1C Localized T2A, T2B , T2C Locally-advanced T3A, T3B , T3C and T4 Metastatic N(0) vs N(+) M(0) vs M(+) 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 comorbid 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 Low risk Int risk High risk clinical stage PSA Gleason score T1c-T2a T2b >T3 <10 10-20 >20 6 7 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) Prognosis = Likelihood of the disease recurring after x years • Serum [PSA] • Stage • Grade Kattan nomograms • Useful tool to examine outcome for similar patients to one’s own using wither preoperative or post-operative data • Developed from a retrospective database that was externally validated • Kattan Multivariable Analysis of the Risk of Biochemical Recurrence N=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 interval Alumkal, et al 2008 Disease States Model of Prostate Cancer Metastatic Hormone-naive Localized PSA Relapse Hormone-naive Metastatic Castrate Metastatic Castrate Docetaxel-resistant PSA Relapse Castrate Death Metastatic Disease Epidural space Lung Liver Bone Lymph nodes 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 Alkaline phosphatase Prostatic acid phosphatase AR and Androgens in Prostate Cancer Mutated AR AR AR Testosterone(T)/ Dihydrotestosterone (DHT) Lower but not absent T/DHT ARE Pre-castrate PSA ARE PSA Castrate-resistant (no longer called “androgen independent”) 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 Death of some cancer cells X “Water down” the gas further Growth and spread despite low levels of testosterone (fuel) 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 Tran, et al Science 2009 • Abiraterone acetate – Reduces adrenal steroidogenesis 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 SIGNALING HATs HDACs AC N- Histone proteins Chromatin remodeling K -C Non-histone proteins (HSP90, Tubulin) Stability (AR, Her2Neu, Bcr-Abl, etc) Gene expression 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 Acetyl AR Active HSP90 Decreased de-acetylation of HSP90 and alpha-tubulin Inactive or reduced X levels of HDAC6 Hyperacetylated, inactive HSP90 HDAC6 X HDAC6 Alpha-tubulin Inactive or reduced levels of HDAC6 X X AR X X HDAC6 Protein instability and proteasomal degradation of AR and HDAC6 Hyperacetylated alpha-tubulin- ? role AR ERG and other AR target genes ERG and other AR target genes 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. ERG X? Benign SFN PIN (Prostate cancer precursor) Klezovitch PNAS 2008 Current Directions with Sulforaphane • Further explore the effect of sulforaphane on prostate cancer cells • 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 Specific gene regulation requires the assembly and coordinate action of demethylases with distinct substrate specificities Non-castrate: ON PSA AR JHDM2A LSD1 JMJD2C Other chromatin modification factors?? Castrate State: REDUCED (NOT OFF) PSA AR LSD1 JMJD2C Metzger, et al Nature 2005 Yamane, et al Cell 2006 Wissman, et al Nature Cell Bio 2007 Other chromatin modification factors?? LSD1 • LSD1 (Lysine specific demethylase 1) Turns off genes – 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 Turns on genes • Which LSD1 gene targets mediate this?? Wysocka, et al 2005 Treatment with a LSD1 small molecule inhibitor reduces PSA 1c Treatment Reduces PSA 8.00 7.00 EXPRESSION 6.00 5.00 4.00 3.00 2.00 ChIP PCR of PSA gene 1.00 0.00 Mock in Presence of Testosterone 1c in Presence of Testosterone Mock in Absence of Testosterone SAMPLE QRTPCR of PSA gene 1c in Absence of Testosterone Check human prostate cancer samples to determine genes whose expression is directly/inversely correlated with LSD1 by expression arrays Vehicle siNTC LSD1 inhibitor siLSD1 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 from Yu, et al 2007 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