EXPERT LECTURE
FUTURE BIOMARKERS IN PROSTATE CANCER
Reviewers
Alexandre de la Taille, Inserm U955Eq07, Créteil, France
Jack Schalken, Radboud University Nijmegen Medical Center,
The Netherlands
PROSTATE CANCER:
WHY ARE NEW BIOMARKERS NEEDED?
Current biomarker system.
Ideal characteristics of a biomarker for prostate cancer
PSA
Produced only by tumour tissue

Non-invasive – easy to manage

As inexpensive as possible to encourage widespread use

Ability to detect prostate cancer at an early stage

Ability to differentiate aggressive tumours leading to death only

High specificity

High sensitivity/low false-positive rate

PSA: Prostate-specific antigen.
PSA screening has not
conclusively
reduced prostate
cancer mortality
Reliable biomarkers
needed to
differentiate between
indolent and
aggressive cancers
PROSTATE CANCER:
WHAT NEW BIOMARKERS ARE AVAILABLE?
Comparison of validated biomarker systems.
Ideal characteristics of a biomarker for prostate cancer
PSA
PCA3
CTCs
TMPRSS2–ERG
Produced only by tumour tissue


?

Non-invasive – easy to manage




As inexpensive as possible to encourage widespread use



?
Ability to detect prostate cancer at an early stage


?
?
Ability to differentiate aggressive tumours leading to death only




High specificity




High sensitivity/low false-positive rate


?

CTC: Circulating tumour cell; PCA3: Prostate cancer antigen 3; TMPRSS: Transmembrane protease, serine.
PCA3
PCA3 mRNA is highly overexpressed
in prostate cancer cells1
Measured in urine after DRE using nucleic
acid amplification
Non-invasive urine-based test
Promising test for prostate cancer detection
REDUCE trial2,3
Yet to be widely adopted in clinical practice
Biospy-negative at 2 years
– PCA3 significantly predicted outcome at 4 years (p < 0.001)
Outperformed PSA
Improved diagnostic accuracy in combination with PSA and other clinical variables
May detect more aggressive and undiagnosed cancers
DRE: Digital rectal examination; mRNA: Messenger ribonucleic acid; PCA3: Prostate cancer antigen 3; PSA: Prostate-specific antigen;
REDUCE: Reduction by dutasteride of prostate cancer events.
1. de Kok JB, Verhaegh GW, Roelofs RW et al. Cancer Res. 62, 2695–2698 (2002).
2. Rittmaster RS, Aubin SM, Reid J et al. ASCO GU, CA, USA, 5–7 March 2010.
3. Groskopf J, Aubin SM, Reid J et al. ASCO GU, CA, USA, 5–7 March 2010.
PCA3:
USE AS DIAGNOSTIC TOOL
Studies evaluating urinary PCA3 levels as a diagnostic tool.
Author (year)
Specificity
(%)
PCA3 test
Patients
(n)
Area under ROC
(95% CI)
Sensitivity
(%)
Marks et al. (2007)1
72
APTIMA
226
0.68 (0.60–0.76)
58
Groskopf et al. (2006)2
79
APTIMA
143
0.75 (0.57–0.92)
69
Fradet et al. (2004)3
89
uPM3™
443
0.86 (0.82–0.89)
66
Tinzl et al. (2004)4
76
uPM3
201
0.87 (0.81–0.92)
82
TRF-based RT-PCR
108
0.72 (0.58–0.85)
Hessels et al. (2003)5
van Gils et al. (2007)6
66
Fluorescence based
534
0.66 (0.61–0.71)
65
Deras et al. (2008)7
74
?
570
0.69
54
Haese et al. (2008)8
72
PROGENSA
463
0.66
47
de la Taille et al. (2009, 74
2010)9,10
PROGENSA
237
0.787
69
CI: Confidence interval; PCA3: Prostate cancer antigen 3; ROC: Receiver operating curve; RT-PCR: Reverse transcriptase polymerase chain reaction;
TRF: Time-resolved fluorescence.
Adapted with permission from: Wright JL, Lsanhe PH. Rev. Urol. 9, 207–213 (2007).
1. Marks LS, Fradet Y, Deras IL et al. Urology 69, 532–535 (2007); 2. Groskopf J, Aubin SM, Reid J et al. ASCO GU, CA, USA, 5–7 March 2010;
3. Fradet Y, Saad F, Aprikian A. Urology 64, 311–315 (2004); 4. Tinzl M, Marberger M, Horvath S, Chypre C. Eur. Urol. 46, 182–186 (2004);
5. Hessels D, Klein Gunnewiek JM, van Oort I et al. Eur. Urol. 44, 8–15 (2003); 6. van Gils MP, Hessels D, van Hooij O et al. Clin. Cancer Res.
13, 939–943 (2007); 7. Deras IL, Aubin SM, Blase A et al. J. Urol. 179, 1587–1592 (2008); 8. Haese A, de la Taille A, van Poppel H et al. Eur. Urol.
54, 1081–1088 (2008); 9. de la Taille A, Irani J, Graefen M et al. EAU, Barcelona, Spain, 16–20 April 2010; 10. de la Taille A, Irani J, de Reijke T,
Graefen M, Kil P, Haese A. Eur. Urol. (Suppl. 8), 193 (2009) (Abstract 292).
PCA3:
USE AS A PROGNOSTIC MARKER
PCA3 score among men scheduled for repeat biopsy.
PCA3 score in:
Patients (n)
Median
Mean
±95% CI
All men with positive repeat biopsy
128
33.7
63.8
47.7–79.8
T1c
81
26.8
56.0
34.5–77.5
T2
30
61.7
88.4
56.9–119.9
Gleason score <7
70
28.1
62.1
35.6–88.6
Gleason score ≥7
52
45.3
68.6
50.8–86.5
Indolent prostate cancer‡
15
21.4
24.5
14.9–34.0
Significant prostate cancer
72
42.1
75.9
50.3–101.5
p-value
0.005
0.0401
0.0059
High-grade PIN = higher mean PCA3 score
Patient numbers in subcategories do not always add up to the total number of patients because of missing data. PCA3 score was calculated by multiplying
the ratio of PCA3 mRNA to PSA mRNA by 1000.
†Wilcox rank sum test.
‡Defined as clinical stage T1c, PSA density <0.15 ng/ml, Gleason score in biopsy ≤6 and positive cores ≤33%.
CI: Confidence interval; PCA3: Prostate cancer antigen 3; PIN: Prostatic intraepithelial neoplasia.
Reprinted from Haese A, de la Taille A, van Poppel H et al. Eur. Urol. 54, 1081–1088 (2008), with permission from Elsevier.
PCA3:
POTENTIAL CLINICAL UTILITY
May detect early prostate cancer more accurately than serum PSA
Preliminary evidence suggests correlation between PCA3 and clinical severity
– May have clinical utility in identifying low-grade/low-volume tumours
Identification of exact PCA3 threshold for prostate cancer detection
More accurate interpretation of results
Increased probability of detecting prostate cancer at repeat biopsy
Prevents repeat negative biopsies
PCA3: Prostate cancer antigen 3; PSA: Prostate-specific antigen.
TMPRSS2–ERG
Non-invasive urine test
First identified gene rearrangement in prostate cancer
ETS-related gene fusions:1,2
– ~50% of prostate cancer patients
– Of these, >90% are TMPRSS2–ERG
– TMPRSS2–ERG is usually absent from benign prostatic tissue
Correlation between TMPRSS2–ERG and prostate cancer prognosis is conflicting3
Chromosome 21
Gene fusion
Occurs in 50%
of cases
TMPRSS2
ERG (oncogene)
Deletion
TMPRSS: Transmembrane protease, serine.
1. Tomlins SA, Rhodes DR, Perner S et al. Science 310, 644–648 (2005).
2. Laxman B, Tomlins SA, Mehra R et al. Neoplasia 8, 885–888 (2006).
3. Tomlins SA, Bjartell A, Chinnaiyan AM et al. Eur. Urol. 56(2), 275–286 (2009).
Fusion gene
TMPRSS2:ERG
TMPRSS2–ERG:
CORRELATION WITH PROSTATE CANCER PROGNOSIS
Studies investigating TMPRSS2–ERG in prostate cancer.
Author (year)
Key result
More aggressive phenotype and poor prognosis
Demichelis et al. (2007)1
Association between:
TMPRSS2–ERG and
Prostate-specific mortality (cumulative incidence ratio: 2.7; p < 0.01)
Good prognosis
Petrovics et al. (2005)2
Winnes et al. (2007)3
Association between:
TMPRSS2–ERG and
Increased disease-free survival, lower Gleason score and no metastases
Superior to PSA
Aubin et al. (2010)4
TMPRSS2–ERG superior to PSA for predicting cancer biopsy outcome
Improved diagnostic accuracy in a model
Day et al. (2010)5
Improved diagnostic accuracy for TMPRSS2–ERG with additional
markers/risk factors vs TMPRSS2–ERG alone
PSA: Prostate-specific antigen; TMPRSS: Transmembrane protease, serine.
1. Demichelis F, Fall K, Perner S et al. Oncogene 26, 4596–4599 (2007); 2. Petrovics G, Liu A, Shaheduzzaman S et al. Oncogene 24, 3847–3852 (2005);
3. Winnes M, Lissbrant E, Damber JE, Stenman G. Oncol. Rep. 17(5), 1033–1036 (2007); 4. Aubin SM, Tomlins SA, Sakamoto K et al. ASCO GU, CA,
USA, 5–7 March 2010; 5. Day JR, Amberson JB, Cochran JS et al. ASCO GU, CA, USA, 5–7 March 2010.
TMPRSS2–ERG:
POTENTIAL CLINICAL UTILITY
Potential biomarker for:
– Diagnosing prostate cancer
– Stratifying risk of prostate cancer patients
Specificity rate of ETS fusions:
– >90% in PSA-screened cohorts
Under assessment as a surrogate end point1
Common gene fusions may alter chemo- and radio-sensitivity of prostate cancer cells2
Association between gene fusions and cancer aggressiveness needs clarification
PSA: Prostate-specific antigen; TMPRSS: Transmembrane protease, serine.
1. ClinicalTrial.gov http://clinicaltrials.gov/ct2/show/NCT01020448?term=Decapeptyl+advanced+prostate+cancer&rank=2.
2. Swanson TA, Marples B, Grills IS et al. ASCO GU, CA, USA, 5–7 March 2010.
CTCs:
THE METASTATIC CASCADE
A. Progression
B
C
A
B. Intravasation
C. CTC dissemination
D
D. Extravasation
E. Colonisation
E
CTC: Circulating tumour cell; EMT: Epithelial–mesenchymal transition.
1. Pantel K, Brakenhoff RH, Brandt B. Nat. Rev. Cancer 8(5), 329–340 (2008).
Frequency of CTCs in blood
depends on the type of
solid tumour1
CTCs:
DETECTION AND TESTS
Tests
Non-invasive blood sampling
Commercially available CellSearch system (Veridex®, Warren, NJ, USA):1,2
– Only CTC technique for metastatic breast, colorectal and prostate cancers
Detection methods3,4
Affinity purification
Molecular analysis (RT-PCR)
Flow-based cell-sorting methods
– Immunofluorescent labelling
– Immunomagnetic labelling
Assessment of telomerase activity
CTC: Circulating tumour cell; RT-PCR: Reverse transcriptase polymerase chain reaction.
1. de Bono JS, Scher HI, Montgomery RB et al. Clin. Cancer Res. 14(1), 6302–6309 (2008).
2. Massard C, Chauchereau A, Fizazi K. Ann. Oncol. 20, 197–199 (2009).
3. Tannock IF, de Wit R, Berry WR et al. TAX 327 Investigators. N. Engl. J. Med. 351(15), 1502–1512 (2004).
4. Fizazi K, Morat L, Chauveinc L et al. Ann. Oncol. 18(3), 518–521 (2007).
CTCs:
CellSearch SYSTEM METHODOLOGY
CellSearch is a non-invasive blood sampling test for CTCs that uses Immunofluorescent
labeling to isolate and count cells
CTC
Leukocyte
EpCAM
Anti-EpCAM
Ferrofluid
Anti-CD45-APC
CD45
Nucleus
DAPI
Nucleus
DAPI
CK
Anti-CK-PE
Anti-CD45-APC: Anti-CD45-allophycocyan; Anti-CK-PE: Anti-cytokeratin 8/18/19-phycoerythrin; CK: Cytokeratin; CTC: Circulating tumour cell;
DAPI: 4,2-diamidino-2-phenylindole, dihydrochloride; EpCAM: Epithelial cell adhesion molecule.
Redrawn with permission from http://veridex.com/pdf/MKG1982PanCancerGTWshortPresentationFINAL.pdf
CTCs IN PROSTATE CANCER
Studies investigating the CellSearch system in prostate cancer.
Author (year)
Key result
Monitoring bone metastases
Thalgott et al. (2010)1
Highest frequencies of CTCs in patients with bone metastases
Use in monitoring chemotherapy in CRPC patients with bone metastases
Predicts overall survival
de Bono et al. (2008)2
Unfavorable pre- and on-treatment CTCs (≥5 CTC/7.5 ml) predicted poor overall
survival
Similar to PSA
Thalgott et al. (2010)1
Early chemotherapy-induced reduction in CTC counts (68%) similar to PSA (59%)
Superior to PSA
De Bono et al. (2008)2
Post-treatment CTC count superior to PSA at predicting overall survival
Minimal correlation between CTC and PSA
Scher et al. (2010)3
ClinicalTrials.gov4
Little correlation between PSA and CTC in progressive CRPC treated with
MDV3100; under further investigation
CRPC: Castration-resistant prostate cancer; CTC: Circulating tumour cell; PSA: Prostate-specific antigen.
1. Thalgott MK, Nawroth R, Andergassen U et al. ASCO GU, CA, USA, 5–7 March 2010.
2. de Bono JS, Scher HI, Montgomery RB et al. Clin. Cancer Res. 14(1), 6302–6309 (2008).
3. Scher HI, Anand A, Beer TM et al. ASCO GU, CA, USA, 5–7 March 2010.
4. ClinicalTrials.gov www.clinicaltrials.gov.
CTCs:
POTENTIAL CLINICAL UTILITY
Enumeration of CTCs is effective for predicting prognosis (overall survival)
CTCs are also associated with the potential of detecting molecular abnormalities1
The use of CTC enumeration as a surrogate marker needs to be validated by large
Phase III trials
CTC: Circulating tumour cell.
1. Massard C, Chauchereau A, Fizazi K. Ann. Oncol. 20, 197–199 (2009).
FUTURE BIOMARKERS
Potential biomarkers under investigation for prostate cancer.
Abbreviation
Name
uPA system and UPAR†
Urokinase plasminogen activation system and urokinase-type
plasminogen activator receptor
TGF-b1†
Transforming growth factor-b1
IL-6†
Interleukin-6
PSP†
Prostate secretory protein
PSMA†
Prostate-specific membrane antigen
GSTP1 methylation‡
Glutathione S-transferase P1 methylation
hK2 (or KLK2)†
Human glandular kallikrein (or kallikrein-2 )
cPSA†
Complexed prostate-specific antigen
Pro-PSA†
Prostate-specific antigen precursor
IGF-1, IGFBP-2 and -3†
Insulin-like growth factor-1 and insulin-like growth factor binding
protein-2 and -3
PCA-specific autoantibodies†
Prostate cancer antigen-specific autoantibodies
AMACR§
a-methylacyl-CoA racemase
†Serum; ‡Urine; §Serum?/urine.
CONCLUSION
PSA is the main prostate cancer biomarker, but it has limitations and poor specificity
New biomarkers:
– Offer improved sensitivity and specificity
– Useful surrogate marker in clinical trials (CTCs for CRPC)
– Improved prognostic value vs PSA (CTCs for CRPC)
– Facilitate diagnosis (PCA3), cancer risk stratification (PCA3 and gene fusion),
and prediction of invasion and metastases
– Predict disease recurrence
– Monitor treatment efficacy (CTCs for CRPC)
– Provide a more reliable tool to assess new therapeutic approaches
(e.g., chemoprevention and gene therapy)
New biomarkers may soon replace or complement PSA
A biomarker panel may be needed
Significant advances in patient management are possible
CRPC: Castration-resistant prostate cancer; CTC: Circulating tumour cell; PSA: Prostate-specific antigen.