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Vickers AJ, Lilja H. Eight Misconceptions about Prostate-Specific Antigen. Clin Chem 2024; 70:13-16. [PMID: 38175588 DOI: 10.1093/clinchem/hvad138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 07/03/2023] [Indexed: 01/05/2024]
Affiliation(s)
- Andrew J Vickers
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, United States
| | - Hans Lilja
- Departments of Pathology and Laboratory Medicine, Surgery, and Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, United States
- Department of Translational Medicine, Lund University, Malmö, Sweden
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2
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Carlsson SV, Murata K, Danila DC, Lilja H. PSA: role in screening and monitoring patients with prostate cancer. Cancer Biomark 2022. [DOI: 10.1016/b978-0-12-824302-2.00001-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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3
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Khan MFL, Soikkeli M, Routila E, Krannila S, Terävä J, Taimen P, Boström PJ, Pettersson K. Clinical Utility of Mutant Antibody-Based Assays for Determination of Internally Cleaved and Intact Forms of Free Prostate-Specific Antigen. J Appl Lab Med 2019; 3:1014-1021. [PMID: 31639692 DOI: 10.1373/jalm.2018.027797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 12/07/2018] [Indexed: 11/06/2022]
Abstract
BACKGROUND Subforms of prostate-specific antigen (PSA) have been a subject of intensive research, and use of multikallikrein immunoassays can add clinical value to the early detection of prostate cancer, overcoming known limitations of PSA. In this study, we evaluated mutant 4D4 (L3-2) antibody-assisted assay constructs against reference wild-type (wt)-4D4-based assays for determination of intact PSA (iPSA) and nicked PSA (nPSA) in plasma samples. METHODS Perioperative plasma samples obtained from 105 men who underwent biopsy (73 cancer, 32 noncancer) were analyzed with sandwich immunoassays for total PSA (tPSA), free PSA (fPSA), iPSA (3 constructs), and measured nPSA (2 constructs). Calculated nPSA (CN) was obtained from total fPSA - iPSA. RESULTS Mutant-assisted iPSA assays measured lower concentrations than the reference in both patient groups. CN separated the 2 groups with the iPSA using the mutant for capture (I-MC) performing the best (P = 0.008). In prostate volume group > median, only measured nPSA provided significant discrimination [area under the curve (AUC), 0.71; P = 0.016] but equally using mutant and wt antibodies. In the whole cohort, all ratios to tPSA performed well (AUC, 0.819-0.870; P ≤ 0.0001) with CN based on I-MC scoring highest (AUC, 0.870). Importantly, in the ≤ median volume group, the I-MC/F and CN(I-MC)/T ratios stand out as the best performing parameters (AUC, 0.825 and 0.861; P = 0.001 and P = 0.0003, respectively). CONCLUSIONS The new assay construct using the mutant 4D4 (L3-2) as a capture provides clear improvement in separating cancer from noncancer in all subgroups analyzed but especially in patients with prostate volume ≤ median.Clinical Trial Registration: ClinicalTrials.gov Identifier NCT01864135.
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Affiliation(s)
- Md Ferdhos L Khan
- Departments of Biochemistry/Biotechnology, University of Turku, Turku, Finland;
| | - Minna Soikkeli
- Departments of Biochemistry/Biotechnology, University of Turku, Turku, Finland
| | - Erica Routila
- Departments of Biochemistry/Biotechnology, University of Turku, Turku, Finland
| | - Sandra Krannila
- Departments of Biochemistry/Biotechnology, University of Turku, Turku, Finland
| | - Joonas Terävä
- Departments of Biochemistry/Biotechnology, University of Turku, Turku, Finland
| | - Pekka Taimen
- Department of Pathology, University of Turku and Turku University Hospital, Turku, Finland
| | - Peter J Boström
- Department of Urology, Turku University Hospital, Turku, Finland
| | - Kim Pettersson
- Departments of Biochemistry/Biotechnology, University of Turku, Turku, Finland
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Higgins CE, Neybold P, Holdridge MB, Barnes CR, Dong Y, Reeve M, Mathur V, Weisberger J, Linder V. Performance of the 4Kscore Test in Plasma and Serum and Stability of the Component Analytes in Clinical Samples. J Appl Lab Med 2019; 3:185-199. [PMID: 33636931 DOI: 10.1373/jalm.2017.024612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 11/27/2017] [Indexed: 01/04/2023]
Abstract
BACKGROUND The 4Kscore Test determines a personalized risk score for aggressive prostate cancer by combining the blood sample measurements of total prostate-specific antigen (tPSA), free PSA (fPSA), intact PSA (iPSA), and human kallikrein-related peptidase 2 (hK2) with patient clinical information to generate the patient risk's score; thus, accuracy and precision of the 4Kscore depend on the reliability of these measurements. Although tPSA and fPSA are measured on a Food and Drug Administration (FDA)-approved platform, the performance of the iPSA and hK2 assays in the clinical setting has not previously been reported. METHODS Analytical performance was determined for the iPSA and hK2 assays in both serum and EDTA plasma, according to Clinical and Laboratory Standards Institute guidelines. Equivalence of the 4Kscore in both sample matrices was demonstrated in a 353-patient clinical cohort, and the stability of endogenous iPSA and hK2 for at least 3 days was demonstrated in a smaller subset. RESULTS Intralaboratory and interlaboratory precision of the iPSA and hK2 assays in both matrices was comparable with that of FDA-approved tPSA and fPSA assays (<18% for iPSA; <8% for hK2). The picogram per milliliter sensitivity and wide dynamic range of the iPSA and hK2 assays allowed for accurate measurements in the target population. The 4Kscore generated in either matrix up to 3 days after collection is equivalent to that measured within 24 h of collection (Passing-Bablok slope 95% CI: plasma, 0.999-1.034; serum, 0.997-1.040). CONCLUSIONS The robust performance of component assays and reliable stability of the endogenous analytes in clinical samples proven here ensures an accurate 4Kscore Test result.
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Affiliation(s)
| | | | | | | | - Yan Dong
- OPKO Diagnostics, LLC, Woburn, MA
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5
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Different mice inbred strains humoral immune response against human prostate-specific antigen. UKRAINIAN BIOCHEMICAL JOURNAL 2019. [DOI: 10.15407/ubj91.01.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Improved cancer specificity in PSA assay using Aleuria aurantia lectin coated Eu-nanoparticles for detection. Clin Biochem 2017; 50:54-61. [DOI: 10.1016/j.clinbiochem.2016.06.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/17/2016] [Accepted: 06/19/2016] [Indexed: 01/02/2023]
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7
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Stephan C, Jung K, Ralla B. Current biomarkers for diagnosing of prostate cancer. Future Oncol 2015; 11:2743-55. [DOI: 10.2217/fon.15.203] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Prostate cancer (PCa) is mostly detected by prostate-specific antigen (PSA) as one of the most widely used tumor markers. But PSA is limited with its low specificity. The prostate health index (phi) can improve specificity over percent free and total PSA and correlates with aggressive cancer. The urinary PCA3 also shows its utility to detect PCa but its correlation with aggressiveness and the low sensitivity at high values are limitations. While the detection of alterations of the androgen-regulated TMPRSS2 and ETS transcription factor genes in tissue of ˜50% of all PCa patients was one research milestone, the urinary assay should only be used in combination with PCA3. Both US FDA-approved markers phi and PCA3 perform equally.
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Affiliation(s)
- Carsten Stephan
- Department of Urology, Charité – Universitätsmedizin Berlin, CCM, Charitéplatz 1, D-10117 Berlin, Germany
- Berlin Institute for Urologic Research, Berlin, Germany
| | - Klaus Jung
- Department of Urology, Charité – Universitätsmedizin Berlin, CCM, Charitéplatz 1, D-10117 Berlin, Germany
- Berlin Institute for Urologic Research, Berlin, Germany
| | - Bernhard Ralla
- Department of Urology, Charité – Universitätsmedizin Berlin, CCM, Charitéplatz 1, D-10117 Berlin, Germany
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8
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Phage display aided improvement of a unique prostate-specific antigen (PSA) antibody unreactive with Lys145–Lys146 internally cleaved forms. J Immunol Methods 2015; 422:72-9. [DOI: 10.1016/j.jim.2015.04.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 04/07/2015] [Accepted: 04/07/2015] [Indexed: 11/22/2022]
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Braun K, Sjoberg DD, Vickers AJ, Lilja H, Bjartell AS. A Four-kallikrein Panel Predicts High-grade Cancer on Biopsy: Independent Validation in a Community Cohort. Eur Urol 2015; 69:505-11. [PMID: 25979570 DOI: 10.1016/j.eururo.2015.04.028] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 04/18/2015] [Indexed: 11/17/2022]
Abstract
BACKGROUND A statistical model based on four kallikrein markers (total prostate-specific antigen [tPSA], free PSA [fPSA], intact PSA, and human kallikrein-related peptidase 2) in blood can predict risk of Gleason score ≥7 (high-grade) cancer at prostate biopsy. OBJECTIVE To determine the value of this model in predicting high-grade cancer at biopsy in a community-based setting in which referral criteria included percentage of fPSA to tPSA (%fPSA). DESIGN, SETTING, AND PARTICIPANTS We evaluated the model, with or without adding blood levels of microseminoprotein-β (MSMB) in a cohort of 749 men referred for prostate biopsy due to elevated PSA (≥3 ng/ml), low %fPSA (<20%), or suspicious digital rectal examination at Skåne University Hospital, Malmö, Sweden. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The kallikrein markers, with or without MSMB levels, measured in cryopreserved anticoagulated blood were combined with age in a published statistical model (Prostate Testing for Cancer and Treatment [ProtecT]) to predict high-grade cancer at biopsy. Predictive accuracy was compared with a base model. RESULTS AND LIMITATIONS The %fPSA was low (median: 17; interquartile range: 13-22) in this cohort because this marker was used as a referral criterion. The ProtecT model improved discrimination over age and PSA for high-grade cancer (0.777 vs 0.720; p=0.002). At one illustrative cut point, use of the panel would reduce the number of biopsies by 236 per 1000 and detect 195 of 208 (94%) but delay diagnosis of 13 of 208 high-grade cancers. MSMB levels in blood did not improve the accuracy of the panel (p=0.2). CONCLUSIONS The kallikrein model is predictive of high-grade cancer if criteria for biopsy referral also include %fPSA, and it can reduce unnecessary biopsies without missing an undue number of tumors. PATIENT SUMMARY We evaluated a published model to predict biopsy outcome in men biopsied due to low percentage of free to total prostate-specific antigen. The model helps reduce unnecessary biopsies without missing an undue number of high-grade cancers.
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Affiliation(s)
- Katharina Braun
- Department of Urology, University Hospital Ruhr-University Bochum, Marien Hospital Herne, Herne, Germany
| | - Daniel D Sjoberg
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Andrew J Vickers
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Hans Lilja
- Departments of Laboratory Medicine, Medicine (Genitourinary Oncology), and Surgery (Urology), Memorial Sloan Kettering Cancer Center, New York, NY, USA; Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK; Department of Translational Medicine, Lund University, Malmö, Sweden.
| | - Anders S Bjartell
- Department of Translational Medicine, Lund University, Malmö, Sweden
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Duskova K, Vesely S. Prostate Specific Antigen. Current clinical application and future prospects. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2015; 159:18-26. [DOI: 10.5507/bp.2014.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 08/29/2014] [Indexed: 11/23/2022] Open
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Stephan C, Ralla B, Jung K. Prostate-specific antigen and other serum and urine markers in prostate cancer. Biochim Biophys Acta Rev Cancer 2014; 1846:99-112. [PMID: 24727384 DOI: 10.1016/j.bbcan.2014.04.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 03/24/2014] [Accepted: 04/01/2014] [Indexed: 11/16/2022]
Abstract
Prostate-specific antigen (PSA) is one of the most widely used tumor markers, and strongly correlates with the risk of harboring from prostate cancer (PCa). This risk is visible already several years in advance but PSA has severe limitations for PCa detection with its low specificity and low negative predictive value. There is an urgent need for new biomarkers especially to detect clinically significant and aggressive PCa. From all PSA-based markers, the FDA-approved Prostate Health Index (phi) shows improved specificity over percent free and total PSA. Other serum kallikreins or sarcosine in serum or urine show more diverging data. In urine, the FDA-approved prostate cancer gene 3 (PCA3) has also proven its utility in the detection and management of early PCa. However, some aspects on its correlation with aggressiveness and the low sensitivity at very high values have to be re-examined. The detection of a fusion of the androgen regulated TMPRSS2 gene with the ERG oncogene (from the ETS family), which acts as transcription factor gene, in tissue of ~50% of all PCa patients was one milestone in PCa research. When combining the urinary assays for TMPRSS2:ERG and PCA3, an improved accuracy for PCa detection is visible. PCA3 and phi as the best available PCa biomarkers show an equal performance in direct comparisons.
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Affiliation(s)
- Carsten Stephan
- Department of Urology, Charité - Universitätsmedizin Berlin, Berlin, Germany; Berlin Institute for Urologic Research, Berlin, Germany.
| | - Bernhard Ralla
- Department of Urology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Klaus Jung
- Department of Urology, Charité - Universitätsmedizin Berlin, Berlin, Germany; Berlin Institute for Urologic Research, Berlin, Germany
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Abstract
This article updates advances in prostate cancer screening based on prostate-specific antigen, its derivatives, and human kallikrein markers. Many men are diagnosed with indolent disease not requiring treatment. Although there is evidence of a survival benefit from screening, the numbers needed to screen and treat remain high. There is risk of exposing men to the side effects of treatment for nonthreatening disease. A screening test is needed with sufficiently good performance characteristics to detect disease at an early stage so treatment may be offered with curative intent, while reducing the number of negative or unnecessary biopsies.
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Affiliation(s)
- Richard J Bryant
- Nuffield Department of Surgical Sciences, John Radcliffe Hospital, University of Oxford, Headley Way, Headington, Oxford OX3 9DU, UK
| | - Hans Lilja
- Nuffield Department of Surgical Sciences, John Radcliffe Hospital, University of Oxford, Headley Way, Headington, Oxford OX3 9DU, UK; Department of Laboratory Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue (Mailbox 213), New York, NY 10065, USA; Department of Surgery (Urology), Memorial Sloan-Kettering Cancer Center, 1275 York Avenue (Mailbox 213), New York, NY 10065, USA; Department of Medicine (GU-Oncology), Memorial Sloan-Kettering Cancer Center, 1275 York Avenue (Mailbox 213), New York, NY 10065, USA.
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Thorek DLJ, Evans MJ, Carlsson SV, Ulmert D, Lilja H. Prostate-specific kallikrein-related peptidases and their relation to prostate cancer biology and detection. Established relevance and emerging roles. Thromb Haemost 2013; 110:484-92. [PMID: 23903407 PMCID: PMC4029064 DOI: 10.1160/th13-04-0275] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 07/17/2013] [Indexed: 01/05/2023]
Abstract
Kallikreins are a family of serine proteases with a range of tissue-specific and essential proteolytic functions. Among the best studied are the prostate tissue-specific KLK2 and KLK3 genes and their secreted protease products, human kallikrein 2, hk2, and prostate-specific antigen (PSA). Members of the so-called classic kallikreins, these highly active trypsin-like serine proteases play established roles in human reproduction. Both hK2 and PSA expression is regulated by the androgen receptor which has a fundamental role in prostate tissue development and progression of disease. This feature, combined with the ability to sensitively detect different forms of these proteins in blood and biopsies, result in a crucially important biomarker for the presence and recurrence of cancer. Emerging evidence has begun to suggest a role for these kallikreins in critical vascular events. This review discusses the established and developing biological roles of hK2 and PSA, as well as the historical and advanced use of their detection to accurately and non-invasively detect and guide treatment of prostatic disease.
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Affiliation(s)
- Daniel L J Thorek
- Hans Lilja, MD, PhD, Memorial Sloan-Kettering Cancer Center, 1275 York Ave Box 213, New York, NY 10065, USA, Tel.: +1 212 639 6982, Fax: +1 646 422 2379, E-mail:
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Carlsson SV, Peltola MT, Sjoberg D, Schröder FH, Hugosson J, Pettersson K, Scardino PT, Vickers AJ, Lilja H, Roobol MJ. Can one blood draw replace transrectal ultrasonography-estimated prostate volume to predict prostate cancer risk? BJU Int 2013; 112:602-9. [PMID: 23448270 DOI: 10.1111/j.1464-410x.2012.11690.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To explore whether a panel of kallikrein markers in blood: total, free and intact prostate-specific antigen (PSA) and kallikrein-related peptidase 2, could be used as a non-invasive alternative for predicting prostate cancer on biopsy in a screening setting. SUBJECTS AND METHODS The study cohort comprised previously unscreened men who underwent sextant biopsy owing to elevated PSA (≥3 ng/mL) in two different centres of the European Randomized Study of Screening for Prostate Cancer, Rotterdam (n = 2914) and Göteborg (n = 740). A statistical model, based on kallikrein markers, was compared with one based on established clinical factors for the prediction of biopsy outcome. RESULTS The clinical tests were found to be no better than blood markers, with an area under the curve in favour of the blood measurements of 0.766 vs. 0.763 in Rotterdam and 0.809 vs. 0.774 in Göteborg. Adding digital rectal examination (DRE) or DRE plus transrectal ultrasonography (TRUS) volume to the markers improved discrimination, although the increases were small. Results were similar for predicting high-grade cancer. There was a strong correlation between the blood measurements and TRUS-estimated prostate volume (Spearman's correlation 0.60 in Rotterdam and 0.57 in Göteborg). CONCLUSIONS In previously unscreened men, each with indication for biopsy, a statistical model based on kallikrein levels was similar to a clinical model in predicting prostate cancer in a screening setting, outside the day-to-day clinical practice. Whether a clinical approach can be replaced by laboratory analyses or used in combination with decision models (nomograms) is a clinical judgment that may vary from clinician to clinician depending on how they weigh the different advantages and disadvantages (harms, costs, time, invasiveness) of both approaches.
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Affiliation(s)
- Sigrid V Carlsson
- Department of Surgery (Urology Service), Memorial Sloan-Kettering Cancer Center, New York, USA; Department of Urology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg
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Peltola MT, Niemelä P, Alanen K, Nurmi M, Lilja H, Pettersson K. Immunoassay for the discrimination of free prostate-specific antigen (fPSA) forms with internal cleavages at Lys(₁₄₅) or Lys(₁₄₆) from fPSA without internal cleavages at Lys(₁₄₅) or Lys(₁₄₆). J Immunol Methods 2011; 369:74-80. [PMID: 21554885 DOI: 10.1016/j.jim.2011.04.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 04/12/2011] [Accepted: 04/19/2011] [Indexed: 11/26/2022]
Abstract
Total levels of circulating prostate-specific antigen (tPSA) are strongly associated with prostate cancer (PCa) risk and outcome but benign prostate disease is the most frequent cause of a moderately elevated PSA level. Free PSA (fPSA) forms are independently associated with PCa risk and contribute modest diagnostic enhancements above and beyond tPSA alone. We developed an immunoassay for fPSA subfractions containing internal cleavages at Lys(145) or Lys(146) (fPSA-N). The assay was based on blocking intact single-chain fPSA (fPSA-I) with antibody 4D4 which does not detect PSA containing internal cleavages at Lys(145) or Lys(146). We also measured fPSA-N in blood from healthy volunteers and in anti-coagulated plasma from 76 men with or without evidence of PCa at biopsy. The analytical and functional detection limits of this assay were 0.016 ng/mL and 0.10 ng/mL, respectively. The median recovery of male fPSA-N from female plasma was 95.0%. All 12 female samples (average age 28 years) had fPSA-N concentrations at or below the analytical detection limit. The median fPSA-N concentration (0.050 ng/mL) in 9 healthy male volunteers (age<40 years) was below the functional detection limit, 0.420 ng/mL in 27 patients with benign prostate conditions and 0.239 ng/mL in 49 patients with PCa. Deming regression analysis of the patient samples showed that the measured fPSA-N concentrations were generally 23% lower than the previously calculated (fPSA minus fPSA-I) concentrations, likely due to differences in the antibody combinations used. In conclusion, we have developed a sensitive, specific and direct immunoassay for fPSA-N which can be used to study the clinical relevance of this PSA isoform.
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Affiliation(s)
- Mari T Peltola
- Department of Biotechnology, University of Turku, Tykistökatu 6 A 6th floor, FIN-20520 Turku, Finland.
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Peltola MT, Niemelä P, Väisänen V, Viitanen T, Alanen K, Nurmi M, Pettersson K. Intact and Internally Cleaved Free Prostate-Specific Antigen in Patients With Prostate Cancer With Different Pathologic Stages and Grades. Urology 2011; 77:1009.e1-8. [DOI: 10.1016/j.urology.2010.11.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 10/26/2010] [Accepted: 11/04/2010] [Indexed: 10/18/2022]
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Bangma CH, van Schaik RH, Blijenberg BG, Roobol MJ, Lilja H, Stenman UH. On the use of prostate-specific antigen for screening of prostate cancer in European Randomised Study for Screening of Prostate Cancer. Eur J Cancer 2010; 46:3109-19. [DOI: 10.1016/j.ejca.2010.09.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Revised: 09/16/2010] [Accepted: 09/17/2010] [Indexed: 10/18/2022]
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Christensson A, Bruun L, Björk T, Cronin AM, Vickers AJ, Savage CJ, Lilja H. Intra-individual short-term variability of prostate-specific antigen and other kallikrein markers in a serial collection of blood from men under evaluation for prostate cancer. BJU Int 2010; 107:1769-74. [PMID: 20955263 DOI: 10.1111/j.1464-410x.2010.09761.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
STUDY TYPE Diagnostic (exploratory cohort). LEVEL OF EVIDENCE 2b. OBJECTIVE To assess variation of total prostate-specific antigen (tPSA), free PSA (fPSA), percent fPSA, human glandular kallikrein 2 (hK2) and intact PSA measured three times within 2 weeks. Knowledge of the variation in an individual's PSA level is important for clinical decision-making. PATIENTS AND METHODS Study participants were 149 patients referred for prostate biopsy, of which 97 had benign disease and 52 had prostate cancer. Three blood samples were drawn with a median of 4 h between first and second samples and 12 days between first and third samples. Variability was described by absolute differences, ratios and intra-individual coefficients of variation. Total PSA, fPSA, hK2 and intact PSA were measured in anticoagulated blood plasma. RESULTS At baseline, the median tPSA was 6.8 (interquartile range, 4.5-9.6) ng/mL. The intra-individual variation was low for all biomarkers, and lowest for tPSA. For 80% of participants, the ratio between first and second time points for tPSA was in the range 0.91-1.09 and the ratio for percent fPSA was in the range 0.89-1.15. Total coefficients of variation between time 1 and 2 for tPSA, fPSA, percent fPSA, hK2 and intact PSA were 4.0%, 6.6%, 6.0%, 9.2% and 9.5%, respectively. The measurements taken several days apart varied more than those taken on the same day, although the variation between both time points was not large. CONCLUSIONS The intra-individual variation for all the kallikrein-like markers studied was relatively small, especially for samples drawn the same day. Few cases are reclassified between the time points. This indicates the high short-term biological and technical reproducibility of the tests in clinical use.
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Affiliation(s)
- Anders Christensson
- Division of Nephrology, Department of Clinical Sciences, Lund University, University Hospital, Malmö, Sweden.
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Djavan B, Eckersberger E, Finkelstein J, Sadri H, Taneja SS, Lepor H. Prostate-specific Antigen Testing and Prostate Cancer Screening. Prim Care 2010; 37:441-59, vii. [DOI: 10.1016/j.pop.2010.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Vickers A, Cronin A, Roobol M, Savage C, Peltola M, Pettersson K, Scardino PT, Schröder F, Lilja H. Reducing unnecessary biopsy during prostate cancer screening using a four-kallikrein panel: an independent replication. J Clin Oncol 2010; 28:2493-8. [PMID: 20421547 DOI: 10.1200/jco.2009.24.1968] [Citation(s) in RCA: 169] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
PURPOSE We previously reported that a panel of four kallikrein forms in blood-total, free, and intact prostate-specific antigen (PSA) and kallikrein-related peptidase 2 (hK2)-can reduce unnecessary biopsy in previously unscreened men with elevated total PSA. We aimed to replicate our findings in a large, independent, representative, population-based cohort. PATIENTS AND METHODS The study cohort included 2,914 previously unscreened men undergoing biopsy as a result of elevated PSA (> or = 3 ng/mL) in the European Randomized Study of Screening for Prostate Cancer, Rotterdam, with 807 prostate cancers (28%) detected. The cohort was randomly divided 1:3 into a training and validation set. Levels of kallikrein markers were compared with biopsy outcome. RESULTS Addition of free PSA, intact PSA, and hK2 to a model containing total PSA and age improved the area under the curve from 0.64 to 0.76 and 0.70 to 0.78 for models without and with digital rectal examination results, respectively (P < .001 for both). Application of the panel to 1,000 men with elevated PSA would reduce the number of biopsies by 513 and miss 54 of 177 low-grade cancers and 12 of 100 high-grade cancers. Findings were robust to sensitivity analysis. CONCLUSION We have replicated our previously published finding that a panel of four kallikreins can predict the result of biopsy for prostate cancer in men with elevated PSA. Use of this panel would dramatically reduce biopsy rates. A small number of men with cancer would be advised against immediate biopsy, but these men would have predominately low-stage, low-grade disease.
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Affiliation(s)
- Andrew Vickers
- Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
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Kokko T, Liljenbäck T, Peltola MT, Kokko L, Soukka T. Homogeneous Dual-Parameter Assay for Prostate-Specific Antigen Based on Fluorescence Resonance Energy Transfer. Anal Chem 2008; 80:9763-8. [DOI: 10.1021/ac801875a] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tiina Kokko
- Department of Biotechnology, University of Turku, Turku, Finland
| | - Tuomo Liljenbäck
- Department of Biotechnology, University of Turku, Turku, Finland
| | - Mari T. Peltola
- Department of Biotechnology, University of Turku, Turku, Finland
| | - Leena Kokko
- Department of Biotechnology, University of Turku, Turku, Finland
| | - Tero Soukka
- Department of Biotechnology, University of Turku, Turku, Finland
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Vickers AJ, Cronin AM, Aus G, Pihl CG, Becker C, Pettersson K, Scardino PT, Hugosson J, Lilja H. A panel of kallikrein markers can reduce unnecessary biopsy for prostate cancer: data from the European Randomized Study of Prostate Cancer Screening in Göteborg, Sweden. BMC Med 2008; 6:19. [PMID: 18611265 PMCID: PMC2474851 DOI: 10.1186/1741-7015-6-19] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 07/08/2008] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Prostate-specific antigen (PSA) is widely used to detect prostate cancer. The low positive predictive value of elevated PSA results in large numbers of unnecessary prostate biopsies. We set out to determine whether a multivariable model including four kallikrein forms (total, free, and intact PSA, and human kallikrein 2 (hK2)) could predict prostate biopsy outcome in previously unscreened men with elevated total PSA. METHODS The study cohort comprised 740 men in Göteborg, Sweden, undergoing biopsy during the first round of the European Randomized study of Screening for Prostate Cancer. We calculated the area-under-the-curve (AUC) for predicting prostate cancer at biopsy. AUCs for a model including age and PSA (the 'laboratory' model) and age, PSA and digital rectal exam (the 'clinical' model) were compared with those for models that also included additional kallikreins. RESULTS Addition of free and intact PSA and hK2 improved AUC from 0.68 to 0.83 and from 0.72 to 0.84, for the laboratory and clinical models respectively. Using a 20% risk of prostate cancer as the threshold for biopsy would have reduced the number of biopsies by 424 (57%) and missed only 31 out of 152 low-grade and 3 out of 40 high-grade cancers. CONCLUSION Multiple kallikrein forms measured in blood can predict the result of biopsy in previously unscreened men with elevated PSA. A multivariable model can determine which men should be advised to undergo biopsy and which might be advised to continue screening, but defer biopsy until there was stronger evidence of malignancy.
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Affiliation(s)
- Andrew J Vickers
- Memorial Sloan-Kettering Cancer Center, Department of Epidemiology and Biostatistics, East 63rd Street, New York, NY 10021, USA.
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Stephan C, Jung K, Lein M, Diamandis EP. PSA and other tissue kallikreins for prostate cancer detection. Eur J Cancer 2007; 43:1918-26. [PMID: 17689069 DOI: 10.1016/j.ejca.2007.06.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Accepted: 06/20/2007] [Indexed: 11/26/2022]
Abstract
Prostate cancer is the most common neoplasia of middle-aged men. Prostate specific antigen (PSA) is the first FDA-approved tumour marker for early detection of cancer and it is now in widespread clinical use. The discovery of different PSA molecular forms in serum (free PSA, PSA complexed with various protease inhibitors) in the early 1990s renewed clinical research to enhance the specificity of PSA. Also, the use of a homologous prostate-localised antigen, human glandular kallikrein 2 (KLK2) may further reduce the number of unnecessary prostate biopsies. More recently, promising data is emerging regarding molecular forms of free PSA (proPSA, BPSA, 'intact' PSA) and other members of the expanded human kallikrein family. These new findings may add substantial clinical information for early detection of prostate cancer.
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Affiliation(s)
- Carsten Stephan
- Department of Urology, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Väisänen V, Peltola MT, Lilja H, Nurmi M, Pettersson K. Intact free prostate-specific antigen and free and total human glandular kallikrein 2. Elimination of assay interference by enzymatic digestion of antibodies to F(ab')2 fragments. Anal Chem 2007; 78:7809-15. [PMID: 17105175 DOI: 10.1021/ac061201+] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Various blood constituents can interfere with immunoassays, usually by binding the Fc portion of antibodies. Our previously developed assays for intact free prostate-specific antigen (PSA), free human kallikrein 2 (hK2), and total hK2 frequently yielded falsely high results despite including an excess of scavenger antibodies. We investigated whether this interference could be eliminated by replacing monoclonal capture or tracer antibodies with F(ab')2 or recombinant Fab fragments. Female heparin plasma samples (n = 1092), which should have negligible PSA and hK2, and male samples (n = 957) were analyzed to identify samples manifesting interference, which then were used to optimize protocols for the immunoassays. We compared original assays (monoclonal antibodies) versus optimized assays (F(ab')2 fragments: denatured mouse IgG added as scavenger) using another set of EDTA plasma (n = 113), heparin plasma (n = 160), and serum samples (n = 171). With the original assays, the frequency of falsely elevated hK2 and intact free PSA was 15 and 13%, respectively. The optimized assays eliminated 70-85% of these falsely elevated results and importantly reduced the magnitude in the remainder. F(ab')2 fragmentation was the most important factor in reducing interference. The optimized intact free PSA, free hK2, and total hK2 assays manifested high accuracy close to the lower limit of detection.
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Affiliation(s)
- Ville Väisänen
- Department of Biotechnology, University of Turku, Turku, Finland.
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Abstract
Screening for prostate cancer is currently based on the assessment of blood prostate specific antigen (PSA). Although PSA was shown to be an adequate tool in prostate cancer screening, beginning from 4.0 ng/mL, its specificity is less significant. In men with a PSA between 4.0 and 10 ng/mL its predictive value is low. Therefore, there is a need for new instruments likely to improve the specificity of blood PSA levels between 4.0 and 10 ng/mL and the screening for prostate cancer in subjects with low PSA. Recent data are reviewed.
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Affiliation(s)
- C Seitz
- Dept. of Urology, Medical University of Vienna, 18-20, Xähringer-Gürte, 1090 Vienna, Austria
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Leinonen J, Niemelä P, Lövgren J, Bocchi L, Pettersson K, Nevanlinna H, Stenman UH. Characterization of monoclonal antibodies against prostate specific antigen produced by genetic immunization. J Immunol Methods 2006; 289:157-67. [PMID: 15251421 DOI: 10.1016/j.jim.2004.04.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2003] [Revised: 03/24/2004] [Accepted: 04/15/2004] [Indexed: 01/07/2023]
Abstract
Prostate specific antigen (PSA) is the most important marker for prostate cancer. Antibodies against minor variants of PSA may be useful in the development of novel diagnostic tests for prostate cancer, but it has been difficult to produce such antibodies by protein immunization. In this study, we have compared the characteristics of monoclonal antibodies (MAbs) obtained by genetic immunization with those obtained by protein immunization. The whole coding region of PSA-cDNA was cloned in a mammalian expression vector pCDNA-3. Six mice were immunized four times by intra-muscular (i.m.) injection of the PSA-pCDNA3 plasmid. The MAbs produced were characterized with respect to subclass, epitope specificity, binding to various molecular forms of PSA and affinity. After intra-muscular injection of DNA, anti-PSA antibodies were detected in the serum of all mice, but the antibody titers were markedly lower than after protein immunization. After fusion of the spleen cells from the mice, five hybridomas producing MAbs to PSA were obtained. The MAbs were of IgG1 and IgG2a isotype and they all recognized equally different forms of free PSA, namely enzymatically active, nicked and proPSA. Epitope mapping showed that these MAbs reacted with the same antigenic regions as those obtained by protein immunization. Thus, genetic immunization leads to production of anti PSA MAbs with similar characteristics to those obtained by immunizing with PSA protein. As applied in the present study, it is less efficient than protein immunization, but it is a useful technique when the antigen is not available in the quantities needed for immunization.
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Affiliation(s)
- Jari Leinonen
- Department of Clinical Chemistry in Biomedicum, Helsinki University Central Hospital, Finland.
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Väisänen V, Pettersson K, Alanen K, Viitanen T, Nurmi M. Free and total human glandular kallikrein 2 in patients with prostate cancer. Urology 2006; 68:219-25. [PMID: 16844459 DOI: 10.1016/j.urology.2006.01.075] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 12/27/2005] [Accepted: 01/30/2006] [Indexed: 11/18/2022]
Abstract
OBJECTIVES The use of prostate-specific antigen (PSA, hK3) results in the overdiagnosis and overtreatment of prostate cancer. Markers are needed that could identify aggressive, fast-growing tumors and help decide which patients would benefit most from aggressive treatment. Human glandular kallikrein 2 (hK2) could be such a marker. The aim of this study was to test how PSA and hK2 could predict the pathologic stage and grade in a set of patients with clinically organ-confined disease. METHODS Heparin plasma was collected from 188 patients who had undergone radical prostatectomy at the Turku University Central Hospital. Total and free PSA, as well as total and free hK2, were measured and the results compared with the pathologic TNM stage, tumor World Health Organization grade, and Gleason score. RESULTS Free and total hK2 performed similarly to PSA in their ability to separate groups of patients with different stages or grades. Concentrations of both kallikreins were significantly different in patients with World Health Organization grade 1 cancer compared with grade 2. Neither marker could separate patients with different Gleason scores. Although PSA concentrations increased most between patients with Stage pT2b and those with pT3a, the increase in hK2 was most pronounced between those with Stage pT3a and those with pT3b. CONCLUSIONS Although hK2 could not predict the cancer stage or grade better than PSA, changes in the hK2 and PSA concentrations occurred at different points in cancer progression. hK2 may have a role in the prognosis of prostate cancer, but additional studies with longer follow-up are required to determine whether hK2 can help when selecting treatment options.
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Affiliation(s)
- Ville Väisänen
- Department of Biotechnology, University of Turku, Turku, Finland.
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Wu P, Koistinen H, Finne P, Zhang W, Zhu L, Leinonen J, Stenman U. Advances in Prostate‐Specific Antigen Testing. Adv Clin Chem 2006; 41:231-261. [DOI: 10.1016/s0065-2423(05)41007-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Naya Y, Fritsche HA, Bhadkamkar VA, Mikolajczyk SD, Rittenhouse HG, Babaian RJ. Evaluation of precursor prostate-specific antigen isoform ratios in the detection of prostate cancer. Urol Oncol 2005; 23:16-21. [PMID: 15885578 DOI: 10.1016/j.urolonc.2004.07.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Accepted: 07/06/2004] [Indexed: 01/03/2023]
Abstract
OBJECTIVE Disease-associated isoforms of the prostate-specific antigen (PSA) have recently been identified. We evaluated the efficacy of using precursor isoforms of PSA (pPSA) and their ratios for the detection of prostate cancer. METHODS Serum concentrations of [-2], [-4], and [-7]pPSA, BPSA, and free PSA (fPSA) were retrospectively measured in 43 selected men. Of the 43 men, 15 had clinical T2 prostate cancer with ultrasound-estimated prostate volumes (PVs) of >50 cm(3), 13 had clinical T2 prostate cancer with (PVs) <25 cm(3), and 15 were prostate cancer-free with PV >50 cm(3). We calculated sum pPSA ([-2]+[-4]+[-7]pPSA). We also compared the ratios of: free/total PSA, [-2]pPSA/fPSA, [-2]pPSA/BPSA, [-2]pPSA/(fPSA-BPSA), [-2]pPSA/(fPSA-sum pPSA), and [-2]pPSA/{fPSA-(sum pPSA+BPSA)} among these three groups. RESULTS The median [-2]pPSA/(fPSA-sum pPSA) ratio was significantly higher in men with prostate cancer with or without large PV compared with men with large PV without prostate cancer. Values for median [-2]pPSA/free PSA ratio were higher in men with prostate cancer with or without large PV compared with men with large PV, and without prostate cancer, but the differences were not statistically significant. CONCLUSIONS In this preliminary study, [-2]pPSA/(fPSA-sum pPSA) ratio was not associated with prostate gland volume but was associated with prostate cancer. This ratio may be useful in the detection of prostate cancer, particularly in men with larger glands.
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Affiliation(s)
- Yoshio Naya
- Department of Urology, The University of Texas M.D. Anderson Cancer Center, Houston, 77030, USA
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32
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Steuber T, Niemela P, Haese A, Pettersson K, Erbersdobler A, Felix Chun KH, Graefen M, Kattan MW, Huland H, Lilja H. Association of free-prostate specific antigen subfractions and human glandular kallikrein 2 with volume of benign and malignant prostatic tissue. Prostate 2005; 63:13-8. [PMID: 15378521 DOI: 10.1002/pros.20156] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND We investigated the association of different subfractions of prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2), such as total PSA (tPSA), complexed PSA (cPSA), free PSA (fPSA), "single-chain Intact fPSA" (fPSA-I), "multi-chain nicked fPSA" (fPSA-N), and total hK2 with volumes of total prostate gland, transition zone (tz), and prostate cancer (PCa) tissue in patients with benign and malignant prostatic disease. METHODS Serum samples were collected from men with negative biopsy (n=164) and PCa (n=252). Total and fPSA were measured using a commercially immunoassay. We measured hK2 and fPSA-I by previously reported in-house research assays specific for hK2 and single-chain, non-cleaved fPSA, respectively. Levels of fPSA-N (=fPSA-fPSA-I) and cPSA (=tPSA-fPSA) were calculated. Total prostate and tz volume were measured using transrectal ultrasound (TRUS); PCa volume was calculated using a computer assisted volumetric program. Association with tz and cancer volumes (CaVols) was performed by linear regression analysis. RESULTS All PSA subfractions and hK2 were associated with tz volume in multivariable linear regression analysis. Only hK2, fPSA, and fPSA-N were significantly associated with CaVol in multivariable analysis, fPSA-I seemed to be cancer related. CONCLUSIONS The multi-chain fPSA-N subfractions of fPSA may be a valuable predictor of both benign prostate hyperplasia (BPH) and CaVol that is likely to be more useful in predicting tz volumes than CaVols. fPSA-I may provide information on cancer without being influenced by the presence of BPH.
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Affiliation(s)
- Thomas Steuber
- Department of Urology, University of Hamburg Eppendorf, Hamburg, Germany.
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Huhtinen P, Soukka T, Lövgren T, Härmä H. Immunoassay of total prostate-specific antigen using europium(III) nanoparticle labels and streptavidin-biotin technology. J Immunol Methods 2005; 294:111-22. [PMID: 15604021 DOI: 10.1016/j.jim.2004.09.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Revised: 07/16/2004] [Accepted: 09/03/2004] [Indexed: 11/24/2022]
Abstract
Nanoparticle labels conjugated with biomolecules are used in a variety of different assay applications. We investigated the possibility of using europium(III)-labeled 68-nm nanoparticles coated with monoclonal antibodies or streptavidin (SA) to detect prostate-specific antigen (PSA) in serum. The selection of a suitable antibody pair and interference caused by the combination of nanoparticle label and structurally complex analyte were of special interest. A set of antibodies recognizing different epitope areas of PSA was mapped to find the optimal antibody pair for the immunometric nanoparticle-based assay. Different assay configurations were tested to obtain a good correlation with a conventional method based on biotinylated detection antibodies and europium(III) chelate-labeled streptavidin. Monoclonal capture antibody 5E4 was covalently coated on a microtitration well surface; biotinylated 5H6 monoclonal antibody (Mab) was used for detection, and europium(III)-labeled streptavidin-coated nanoparticles were utilized for signal generation. Total PSA concentrations were determined from a panel of male serum samples to test the developed assay. The correlation of the nanoparticle-based and reference assays was good; y=0.9844x-0.1252, R2=0.98, n=27; and the lowest limit of detection of the assay (LLD=0.83 ng/l) was 35-fold lower than for the reference method. The assay application presented here, where a structurally complex analyte is detected, combines the exceptionally high affinity of streptavidin-biotin technology and the high specific activity of long lifetime fluorescence nanoparticle labels. The general characteristics of this combination should permit the development of various immunoassay applications featuring high sensitivity, rapidity, and low consumption of reagents.
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Affiliation(s)
- Petri Huhtinen
- Department of Biotechnology, University of Turku, Tykistökatu 6, FIN-20520 Turku, Finland.
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Väisänen V, Eriksson S, Ivaska KK, Lilja H, Nurmi M, Pettersson K. Development of sensitive immunoassays for free and total human glandular kallikrein 2. Clin Chem 2004; 50:1607-17. [PMID: 15247158 DOI: 10.1373/clinchem.2004.035253] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Free and total human kallikrein 2 (hK2) might improve the discrimination between prostate cancer and benign prostatic hyperplasia. Concentrations of hK2 are 100-fold lower than concentrations of prostate-specific antigen (PSA); therefore, an hK2 assay must have a low detection limit and good specificity. METHODS PSA- and hK2-specific monoclonal antibodies were used in solid-phase, two-site immunofluorometric assays to detect free and total hK2. The total hK2 assay used PSA-specific antibodies to block nonspecific signal. The capture antibody of the free hK2 assay did not cross-react with PSA. To determine the hK2 concentrations in the male bloodstream, total hK2 was measured in a control group consisting of 426 noncharacterized serum samples. Free and total hK2 were measured in plasma from 103 patients with confirmed prostate cancer. RESULTS All 426 males in the control group had a total hK2 concentration above the detection limit of 0.0008 microg/L. The median total hK2 concentration was 0.022 microg/L (range, 0.0015-0.37 microg/L). hK2 concentrations were 0.1-58% of total PSA (median, 3.6%). hK2 concentrations were similar in men 41-50 and 51-60 years of age. The ratio of hK2 to PSA steadily decreased from 5-30% at PSA <1 microg/L to 1-2% at higher PSA concentrations. In 103 patients with prostate cancer, the median hK2 concentration in plasma was 0.079 microg/L (range, 0.0015-16.2 microg/L). The median free hK2 concentration was 0.070 (range, 0.005-12.2) microg/L. The proportion of free to total hK2 varied from 17% to 131% (mean, 85%). CONCLUSIONS The wide variation in the free-to-total hK2 ratio suggests that hK2 in blood plasma is not consistently in the free, noncomplexed form in patients with prostate cancer. The new assay is sufficiently sensitive to be used to study the diagnostic accuracies of free and total hK2 for prostate cancer.
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Affiliation(s)
- Ville Väisänen
- University of Turku, Department of Biotechnology, Finland.
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Mikolajczyk SD, Song Y, Wong JR, Matson RS, Rittenhouse HG. Are multiple markers the future of prostate cancer diagnostics? Clin Biochem 2004; 37:519-28. [PMID: 15234233 DOI: 10.1016/j.clinbiochem.2004.05.016] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2004] [Indexed: 01/18/2023]
Abstract
Prostate specific antigen (PSA) is the most successful and widely employed cancer serum marker in use today. There is growing evidence that the introduction of wide PSA screening and earlier detection can result in decreased cancer mortality associated with a decline in metastatic disease. PSA circulates in a number of distinct forms. Measurement of these in addition to total PSA significantly increases diagnostic utility. Diagnostic utility is likely to be further increased by adding kallikreins, cytokines, growth factors, receptors and cellular adhesion factors to the biomarker panel. The need for multiple markers reflects the multidimensional nature of prostate disease which ranges from metastatic cancer to indolent cancer to benign hyperplasia and inflammation, all of which require distinct treatments and medical interventions.
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Haese A, Graefen M, Huland H, Lilja H. Prostate-specific antigen and related isoforms in the diagnosis and management of prostate cancer. Curr Urol Rep 2004; 5:231-40. [PMID: 15161573 DOI: 10.1007/s11934-004-0042-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Despite its unparalleled merits for prostate cancer detection and staging, prostate-specific antigen (PSA) is not a marker for prostate cancer only, but also is expressed in benign conditions. For early detection, limitations of PSA are obvious. Its widespread use has led to an extensive amount of expensive and often unnecessary diagnostic procedures associated with significant morbidity. Total PSA derivatives may enhance the accuracy of prostate cancer diagnosis. The ratio of free-to-total PSA improves specificity while maintaining a high sensitivity for prostate cancer detection for men with a total PSA of 2.5 to 10 ng/mL. Human glandular kallikrein also has the potential to be a valuable tool in combination with total and free PSA for early diagnosis of prostate cancer. Complex PSA seems to be a reliable tool to improve specificity at high sensitivity levels in men with suspected prostate cancer (mainly in PSA levels below 4 ng/mL). Newly discovered isoforms of free PSA also may impact early detection of prostate cancer with encouraging preliminary results that warrant further clinical investigation.
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Affiliation(s)
- Alexander Haese
- Department of Urology, University Clinic Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
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Bangma CH, Wildhagen MF, Yurdakul G, Schröder FH, Blijenberg BG. The value of (−7, −5)pro-prostate-specific antigen and human kallikrein-2 as serum markers for grading prostate cancer. BJU Int 2004; 93:720-4. [PMID: 15049979 DOI: 10.1111/j.1464-410x.2003.04733.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To assess the value of the precursor form (-7,5pro) of prostate-specific antigen (PSA) and human kallikrein-2 (hK2) for detecting and grading prostate cancer, as better serum markers with improved specificity are needed in men with lower ranges of total (t)PSA. PATIENTS AND METHODS tPSA, free PSA (fPSA), the precursor (-7,5)proPSA and hK2 were measured in a subset of participants of the European Randomised Study of Screening of Prostate Cancer. In a pilot study, sera from 143 men biopsied but with no prostate cancer, 142 with BPH, and 146 with prostate cancer were analysed to determine the relative value of serum markers for differentiating between the groups. Then, in 141 men with prostate cancer who had a radical prostatectomy, these serum markers were related to the pathological grading to analyse their value as prognostic variables. RESULTS Levels of (-7,5)proPSA, hK2 and fPSA could be used to distinguish between BPH and cancer, but proPSA and hK2, alone or combined, did not improve the specificity of fPSA for discriminating BPH and cancer. There was also no correlation between these serum markers and pathological tumour grade. CONCLUSION The clinical effect of using (-7,5)proPSA or hK2 for detecting and grading prostate cancer remains limited.
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Affiliation(s)
- C H Bangma
- Department of Urology, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, the Netherlands.
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Djavan B, Fong YK, Remzi M, Fakhari M, Marberger M. New Serum and Urinary Markers for Prostate Cancer Detection in the New Millennium. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.eursup.2004.02.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Wu P, Stenman UH, Pakkala M, Närvänen A, Leinonen J. Separation of enzymatically active and inactive prostate-specific antigen (PSA) by peptide affinity chromatography. Prostate 2004; 58:345-53. [PMID: 14968435 DOI: 10.1002/pros.10337] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Prostate-specific antigen (PSA) is a serine protease with highly prostate-specific expression and an important marker for prostate cancer. We have previously identified novel PSA-binding peptides that enhance the enzymatic activity of PSA when produced as fusion proteins. METHOD PSA-binding peptides and derivatives with a spacer were chemically synthesized and used to prepare an affinity column, which was used to fractionate PSA in seminal plasma, serum, and LNCap cell culture medium. RESULTS Approximately 67% of seminal plasma PSA bound to the peptide affinity column and was eluted under mild conditions. Eluted PSA was intact and enzymatically active while the unbound fraction mainly contained various nicked forms. ProPSA from LNCap cells bound to the peptide column only after activation by trypsin. CONCLUSIONS PSA-binding peptides can be used to separate enzymatically active and inactive forms of PSA. Thus the peptides are potentially useful as ligands for development of methods for specific detection of active free PSA.
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Affiliation(s)
- Ping Wu
- Department of Clinical Chemistry, Helsinki University Central Hospital, Helsinki, Finland
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Abstract
The PSA revolution that has occurred over the previous 2 decades has positively impacted the detection and treatment of men with prostate cancer. Although methods to improve specificity have shown promise (eg, PSAD, age-specific PSA, and PSA velocity), meaningful interpretation has yet to be uniformly accepted within clinical practice. The identification of other molecular forms of PSA within serum has led to a new era in PSA markers. Initial application employing %fPSA has provided improved discrimination between benign and malignant prostatic disease; however, questions remain regarding the ultimate threshold value. The discovery of various free forms of PSA--such as proPSA, BPSA, and iPSA--also have introduced the potential for improved specificity in detection. Although early results are encouraging, further evaluation is anticipated. The development of improved methods to detect and measure cPSA has demonstrated provocative results, and exhibits the potential to replace PSA as a standard diagnostic test in cancer screening.
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Affiliation(s)
- Matthew B Gretzer
- The James Buchanan Brady Urological Institute, Johns Hopkins Hospital, 600 N. Wolfe St./Marburg 1A, Baltimore, MD 21287, USA.
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41
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Haese A, Vaisanen V, Finlay JA, Pettersson K, Rittenhouse HG, Partin AW, Bruzek DJ, Sokoll LJ, Lilja H, Chan DW. Standardization of two immunoassays for human glandular kallikrein 2. Clin Chem 2003; 49:601-10. [PMID: 12651813 DOI: 10.1373/49.4.601] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Measurement of human kallikrein 2 (hK2) has improved early detection and staging of prostate cancer. However, reported concentrations of hK2 among currently used assays have not been standardized in any way. We compared two hK2 assays and five different recombinant hK2 variants (rhK2) and suggest a common calibrator as an important step and putative reference substance in hK2 assay standardization. METHODS We measured 146 sera by two hK2 assays, using assay-specific calibrators to assess the difference between the two assays. Serial dilutions of five rhK2 preparations were measured repeatedly, with one preparation assigned as calibrator and the others as unknowns to define which variant provided the closest match between the two assays. This rhK2 variant was used to recalibrate both assays. We measured hK2 concentrations in the same 146 patients to evaluate the change in the difference. RESULTS Use of assay-specific calibrators for comparison of the two assays yielded a Deming regression equation of: y = 0.789 (95% confidence interval, 0.674-0.922)x + 0.014 (0.004-0.025) micro g/L; R(2) = 0.667. Analysis of five rhK2 variants revealed that the enterokinase (ek)-rhK2 form provided the best match between both assays. Using the ek-rhK2 as a common calibrator, we observed a change in the slope of the regression curve to: y = 1.106 (0.872-1.340)x + 0.006 (-0.002 to 0.016) micro g/L; R(2) = 0.648, suggesting an increase in the mean estimate of agreement between the two assays. CONCLUSION Calibration with a common calibrator substantially increased agreement between the assays. The ek-rhK2 variant provided the best performance of all tested rhK2 variants and should undergo mass spectrometry and amino acid analysis for exact mass determination and value assignment to evaluate its potential as a reference material for immunoassays for hK2.
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Affiliation(s)
- Alexander Haese
- Department of Urology, The James Buchanan Brady Urological Institute, The Johns Hopkins University Medical Institutions, Baltimore, MD 21287, USA.
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Steuber T, Nurmikko P, Haese A, Pettersson K, Graefen M, Hammerer P, Huland H, Lilja H. Discrimination of benign from malignant prostatic disease by selective measurements of single chain, intact free prostate specific antigen. J Urol 2002; 168:1917-22. [PMID: 12394676 DOI: 10.1016/s0022-5347(05)64263-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE Free prostate specific antigen (PSA) in serum consists of heterogeneous molecular subforms. Recently we developed an immunoassay for selective measurement of a subfraction of free PSA called intact PSA, which has been shown to be closely associated with prostate cancer. We assessed the ability of serum intact PSA to discriminate between benign and malignant prostatic disease. MATERIALS AND METHODS In serum of 178 men with benign disease and 255 men with prostate cancer we measured total PSA and free PSA using a commercially available immunoassay. Intact PSA levels were analyzed by a newly developed assay specific for noncleaved, that is single chain forms of free PSA. Internally cleaved "nicked" PSA was calculated by subtracting intact from free PSA. We also calculated ratios of intact PSA-to-free PSA (intact-to-free PSA) and nicked PSA-to-total PSA (nicked-to-total PSA). We compared means, medians and ranges of all analytes and ratios in patients with and without cancer for the entire total PSA range and in a subset with total PSA ranging from 2 to 10 ng./ml. Furthermore, various combinations of PSA forms were tested for their predictive ability. For statistical comparison we used the Mann-Whitney U test and ROC analysis. RESULTS The ratio intact-to-free PSA was significantly higher in cancer (median 48.5%) compared to noncancer cases (median 41.8%, p <0.0001). Conversely, the ratio nicked-to-total PSA was significantly higher in men without compared to those with prostate cancer (median 11.0% and 6.0%, respectively, p <0.0001). Highest discriminative ability was observed for a combination of intact, total and free PSA (log [intact, free, total], AUC = 0.773) followed by nicked-to-total PSA (AUC 0.755). In the subgroup of patients with total PSA levels from 2 to 10 ng./ml. only the AUC of log intact, free, total (AUC 0.706, p = 0.0017) and nicked-to-total PSA (AUC 0.704,p = 0.0019) were significantly larger compared to the AUC of total PSA (AUC 0.602). CONCLUSIONS By contrast to measuring crude free PSA concentration, selective determination of specific free PSA subforms, intact PSA and nicked PSA proved to be useful to discriminate men with benign from malignant prostatic disease. These markers may serve to generate specific serum profiles of PSA for improved specificity and early detection of prostate cancer. To translate the encouraging statistical advantage shown in this study into a clinically applicable tool warrants further investigation.
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Affiliation(s)
- Thomas Steuber
- Department of Urology, University of Hamburg Eppendorf, Germany
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Discrimination of Benign From Malignant Prostatic Disease by Selective Measurements of Single Chain, Intact Free Prostate Specific Antigen. J Urol 2002. [DOI: 10.1097/00005392-200211000-00006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Mikolajczyk SD, Marks LS, Partin AW, Rittenhouse HG. Free prostate-specific antigen in serum is becoming more complex. Urology 2002; 59:797-802. [PMID: 12031356 DOI: 10.1016/s0090-4295(01)01605-3] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Becker C, Noldus J, Diamandis E, Lilja H. The role of molecular forms of prostate-specific antigen (PSA or hK3) and of human glandular kallikrein 2 (hK2) in the diagnosis and monitoring of prostate cancer and in extra-prostatic disease. Crit Rev Clin Lab Sci 2001; 38:357-99. [PMID: 11720279 DOI: 10.1080/20014091084236] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Prostate-specific antigen (PSA or hK3) is a glandular kallikrein with abundant expression in the prostate that is widely used to detect and monitor prostate cancer (PCa), although the serum level is frequently elevated also in benign and inflammatory prostatic diseases. PSA testing is useful for early detection of localized PCa and for the detection of disease recurrence after treatment. However, PSA has failed to accurately estimate cancer volume and preoperative staging. There is no PSA level in serum that definitively distinguishes men with benign conditions from those with prostate cancer, although PCa is rare in men with PSA levels in serum < 2.0 ng/ml. This prompted searches for enhancing parameters to combine with PSA testing, such as PSA density, PSA velocity, and age-specific reference ranges. Due to the protease structure, PSA occurs in different molecular forms in serum and their concentrations vary according to the type of prostatic disease. Human glandular kallikrein 2 (hK2) is very similar to PSA, but expressed at higher levels in prostate adenocarcinoma than in normal prostate epithelium. Blood testing for hK2 combined with different PSA forms improves discrimination of men with benign prostatic disease from those with prostate cancer. Many data have also been reported on the extra-prostatic expression of both PSA and hK2, and it is now believed that they may both have functions in tissues outside the prostate.
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Affiliation(s)
- C Becker
- Dept. of Clinical Chemistry, Lund University, Malmö University Hospital, Malmö, Sweden.
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Nurmikko P, Pettersson K, Piironen T, Hugosson J, Lilja H. Discrimination of Prostate Cancer from Benign Disease by Plasma Measurement of Intact, Free Prostate-specific Antigen Lacking an Internal Cleavage Site at Lys145-Lys146. Clin Chem 2001. [DOI: 10.1093/clinchem/47.8.1415] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractBackground: The proportion of free prostate-specific antigen (PSA) is higher in the sera of patients with benign prostatic hyperplasia compared with patients with prostate cancer (PCa). We developed an immunoassay that measures intact, free PSA forms (fPSA-I), but does not detect free PSA that has been internally cleaved at Lys145-Lys146 (fPSA-N), and investigated whether this form could discriminate patients with PCa from those without PCa.Methods: The assay for fPSA-I uses a novel monoclonal antibody (MAb) that does not detect PSA that has been internally cleaved at Lys145-Lys146. A MAb specific for free PSA was used as a capture antibody, and purified recombinant proPSA was used as a calibrator. The concentrations of fPSA-I, free PSA (PSA-F), and total PSA (PSA-T) were analyzed in EDTA-plasma samples (n = 276) from patients who participated in a screening program for PCa (PSA-T, 0.83–76.3 μg/L).Results: The detection limit of the fPSA-I assay was 0.035 μg/L. Both the measured concentrations of fPSA-I and the concentrations of fPSA-N (calculated as PSA-F − fPSA-I) provided statistically significant discrimination of the two clinical groups. By contrast, PSA-F did not discriminate between these groups. Each of the ratios fPSA-I/PSA-F, fPSA-N/PSA-T, and PSA-F/PSA-T separated cancer samples from noncancer samples in a statistically significant manner (P <0.0001). The ratio fPSA-I/PSA-F was significantly higher in cancer (median, 59%) compared with noncancer samples (47%).Conclusions: The ratio fPSA-I/PSA-F is significantly higher in cancer compared with noncancer. The percentages of both fPSA-N/PSA-T and fPSA-I/PSA-F may provide interesting diagnostic enhancements alone or in combination with other markers and require further studies.
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Affiliation(s)
- Pauliina Nurmikko
- Department of Biotechnology, University of Turku, Tykistökatu 6A 6th floor, FIN-20520 Turku, Finland
| | - Kim Pettersson
- Department of Biotechnology, University of Turku, Tykistökatu 6A 6th floor, FIN-20520 Turku, Finland
| | - Timo Piironen
- The Finsen Laboratory, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Jonas Hugosson
- Department of Urology, Sahlgrenska University Hospital, 5-41345 Göteborg, Sweden
| | - Hans Lilja
- Department of Clinical Chemistry, Lund University, University Hospital, S-20502 Malmö, Sweden
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Björk T, Schalken J, Wittjes W, Ljungberg B, Lilja H. Similar rates of exponential decrease in serum concentrations of free prostate-specific antigen (PSA), PSA complexed to alpha-1-antichymotrypsin, and human glandular kallikrein 2 (hK2) in prostate cancer patients treated with GnRH-analogues. Prostate 2001; 47:14-20. [PMID: 11304725 DOI: 10.1002/pros.1042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Our recently reported finding of rapid bi-exponential elimination of free prostate-specific antigen (PSA) after radical retropubic prostatectomy in patients with moderately elevated PSA levels, which contrasted a very slow, linear elimination of PSA complexed to alpha-1-antichymotrypsin (ACT), prompted us to study whether these elimination rates were applicable for patients selected for castration treatment with very high pretreatment concentrations of PSA in serum. In addition, serum concentrations of hK2, the activator of proPSA, were measured. METHODS Pretreatment serum was obtained from 21 previously untreated prostate cancer patients due for hormonal treatment with a GnRH-analog. Samples were also collected during treatment up to a minimum of 24 weeks at 2-week intervals and analyzed with immunofluorometric assays for free PSA (PSA-F), PSA complexed to alpha-1-antichymotrypsin (PSA-ACT), total PSA (PSA-T), and human kallikrein 2 (hK2). For pharmaco-kinetic analysis the serum concentrations of hK2 and PSA forms for each patient were plotted against time both before and after logarithmic transformation and the half-lives were calculated as ln2/k. RESULTS Median pretreatment serum concentrations were 322 ng/ml (range, 1.9-2210) for PSA-T, 27.8 ng/ml (range, 1.14-259) for PSA-F, and 207 ng/ml (range, 0.8-2080) for PSA-ACT. All patients had castrate levels of serum testosterone (< 2.5 nmol/l) in less than 21 days after initiation of GnRH-analog treatment. It was possible to evaluate data from 19/21 patients which showed an exponential decrease of all PSA concentrations in serum, with mean half-lives of 12.9 days (range, 7.3-30) for PSA-T, 15.5 days (range, 7.7-37.5) for PSA-F, and 12.3 days (range, 6.6-30) for PSA-ACT. Median pretreatment percent free PSA (PSA-F/PSA-T) was 12% compared to 18% at nadir. The median pretreatment level of hK2 was 3.5 ng/ml (range, 0.29-30.3). There was an exponential decrease in hK2 concentrations in serum after initiation of hormonal treatment with a mean half-life of 18.7 days (range, 7.5-37.5). CONCLUSIONS For the majority of patients with hormonally treated prostate cancer the serum concentrations of PSA-T, PSA-F, PSA-ACT, and hK2 decreased slowly in parallel and mono-exponentially after initiation of treatment. Mean half-lives were between 12 and 19 days.
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Affiliation(s)
- T Björk
- Department of Urology, Malmö and Lund University Hospitals, Lund University, Malmö, Sweden.
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