LIMITATIONS IN THE USE OF SERUM PROSTATE SPECIFIC ANTIGEN LEVELS TO MONITOR PATIENTS AFTER TREATMENT FOR PROSTATE CANCER

The impact of the apparent diffusion coefficient for the early prediction of the treatment response after definitive radiotherapy in prostate cancer patients

PURPOSE

We assessed early changes in apparent diffusion coefficient (ADC) and serum prostate specific antigen (PSA) values after definitive radiotherapy (RT) without androgen deprivation treatment in low- and intermediate-risk prostate cancer (PC) patients.

MATERIALS AND METHODS

The clinical data and ADC parameters of 229 PC patients were retrospectively evaluated. Pre-treatment and post-treatment serum PSA and primary tumor ADC values were calculated. Post-treatment DW-MRI was performed median 4.1 months after completion of definitive RT. The prognostic factors predicting freedom from biochemical failure (FFBF) and progression-free survival (PFS) were analyzed using univariable and multivariable analyses.

RESULTS

With a median follow-up time of 80.8 months, the 5-year FFBF and PFS rates were 95.9% and 89.3%, respectively. Eleven patients (4.8%) had PSA relapse, with a median of 34.4 months after the completion of RT. A statistically significant difference in post-treatment ADC values was noted between patients with and without recurrence (0.94 ± 0.07 vs. 1.10 ± 0.20 × 10^-3 mm²/sec; p < 0.001). Patients with a Gleason score (GS) of 6 and low-risk disease had significantly higher post-treatment tumor ADC and PSA levels than patients with a GS of 7 and intermediate-risk disease. The 5-year FFBF rate in patients with tumor ADC ≤ 0.96 × 10^-3 mm²/sec was significantly lower than patients with tumor ADC > 0.96 × 10^-3 mm²/sec (85.5% vs. 100; p < 0.001). In the multivariable analysis, a lower ADC value, GS 4 + 3 and intermediate-risk disease were independent predictors of worse FFBF. In the multivariate analysis, a lower post-treatment ADC value and a GS of 4+3 were significant prognostic factors for a lower PFS.

CONCLUSION

These findings suggest that the post-treatment tumor ADC value could be used for early treatment response evaluation after definitive RT in PC patients.

Novel omics technology driving translational research in precision oncology

In this review, we summarize the current challenges faced by cancer researchers and motivate the use of novel genomics solutions. We follow this up with a comprehensive overview of three recent genomics technologies: liquid biopsy, single-cell RNA sequencing and spatial transcriptomics. We discuss a few representative protocols/assays for each technology along with their strengths, weaknesses, optimal use-cases, and their current stage of clinical deployment by summarizing trial data. We focus on how these technologies help us develop a better understanding of cancer as a rapidly evolving heterogeneous genetic disease that modulates its immediate microenvironment leading to systemic macro-level changes in the patient body. We summarize the review with a flowchart that integrates these three technologies in the existing workflows of clinicians and researchers toward robust detection, accurate diagnosis, and precision oncology.

Serum Proteomics on the Basis of Discovery of Predictive Biomarkers of Response to Androgen Deprivation Therapy in Advanced Prostate Cancer

BACKGROUND

We investigated the serum proteome of hormone-sensitive prostate cancer patients to determine candidate biomarkers associated with androgen deprivation therapy (ADT) efficacy.

PATIENTS AND METHODS

Serum proteomes generated using isobaric mass tags for relative and absolute quantitation were analyzed using reverse-phase liquid chromatography coupled to tandem mass spectrometry. The advanced hormone-sensitive prostate cancer cohorts studied were: (1) untreated "paired" pre-ADT and 4-month post-ADT hormone-sensitive patients (n = 15); (2) "early ADT failure" patients (n = 10) in whom ADT treatment failed within a short period of time; and (3) "late ADT failure" patients (n = 10) in whom ADT treatment failed after a prolonged response time. Differential abundance was assessed, and ingenuity pathway analysis (IPA) was used to identify interaction networks in selected candidates from these comparisons.

RESULTS

Between "post-ADT" and combined "early" and "late" ADT failure groups 149 differentially detected candidates were observed, and between "early" and "late" ADT failure groups 98 candidates were observed; 47 candidates were common in both comparisons. IPA network enrichment analysis of the 47 candidates identified 3 interaction networks (P < .01) including 17-β-estradiol, nuclear factor kappa-light-chain enhancer of activated B cells complex, and P38 mitogen-activated protein kinases as pathways with potential markers of response to ADT.

CONCLUSION

A global proteomic analysis identified pathways with markers of ADT response, which will need validation in independent data sets.

Methods for the evaluation of biomarkers in patients with kidney and liver diseases: multicentre research programme including ELUCIDATE RCT

Background

Protein biomarkers with associations with the activity and outcomes of diseases are being identified by modern proteomic technologies. They may be simple, accessible, cheap and safe tests that can inform diagnosis, prognosis, treatment selection, monitoring of disease activity and therapy and may substitute for complex, invasive and expensive tests. However, their potential is not yet being realised.

Design and methods

The study consisted of three workstreams to create a framework for research: workstream 1, methodology – to define current practice and explore methodology innovations for biomarkers for monitoring disease; workstream 2, clinical translation – to create a framework of research practice, high-quality samples and related clinical data to evaluate the validity and clinical utility of protein biomarkers; and workstream 3, the ELF to Uncover Cirrhosis as an Indication for Diagnosis and Action for Treatable Event (ELUCIDATE) randomised controlled trial (RCT) – an exemplar RCT of an established test, the ADVIA Centaur® Enhanced Liver Fibrosis (ELF) test (Siemens Healthcare Diagnostics Ltd, Camberley, UK) [consisting of a panel of three markers – (1) serum hyaluronic acid, (2) amino-terminal propeptide of type III procollagen and (3) tissue inhibitor of metalloproteinase 1], for liver cirrhosis to determine its impact on diagnostic timing and the management of cirrhosis and the process of care and improving outcomes.

Results

The methodology workstream evaluated the quality of recommendations for using prostate-specific antigen to monitor patients, systematically reviewed RCTs of monitoring strategies and reviewed the monitoring biomarker literature and how monitoring can have an impact on outcomes. Simulation studies were conducted to evaluate monitoring and improve the merits of health care. The monitoring biomarker literature is modest and robust conclusions are infrequent. We recommend improvements in research practice. Patients strongly endorsed the need for robust and conclusive research in this area. The clinical translation workstream focused on analytical and clinical validity. Cohorts were established for renal cell carcinoma (RCC) and renal transplantation (RT), with samples and patient data from multiple centres, as a rapid-access resource to evaluate the validity of biomarkers. Candidate biomarkers for RCC and RT were identified from the literature and their quality was evaluated and selected biomarkers were prioritised. The duration of follow-up was a limitation but biomarkers were identified that may be taken forward for clinical utility. In the third workstream, the ELUCIDATE trial registered 1303 patients and randomised 878 patients out of a target of 1000. The trial started late and recruited slowly initially but ultimately recruited with good statistical power to answer the key questions. ELF monitoring altered the patient process of care and may show benefits from the early introduction of interventions with further follow-up. The ELUCIDATE trial was an ‘exemplar’ trial that has demonstrated the challenges of evaluating biomarker strategies in ‘end-to-end’ RCTs and will inform future study designs.

Conclusions

The limitations in the programme were principally that, during the collection and curation of the cohorts of patients with RCC and RT, the pace of discovery of new biomarkers in commercial and non-commercial research was slower than anticipated and so conclusive evaluations using the cohorts are few; however, access to the cohorts will be sustained for future new biomarkers. The ELUCIDATE trial was slow to start and recruit to, with a late surge of recruitment, and so final conclusions about the impact of the ELF test on long-term outcomes await further follow-up. The findings from the three workstreams were used to synthesise a strategy and framework for future biomarker evaluations incorporating innovations in study design, health economics and health informatics.

Trial registration

Current Controlled Trials ISRCTN74815110, UKCRN ID 9954 and UKCRN ID 11930.

Funding

This project was funded by the NIHR Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 6, No. 3. See the NIHR Journals Library website for further project information.

Diffusion-weighted magnetic resonance imaging in patients with prostate cancer treated with radiotherapy

AIMS

To evaluate the utility of a multiparametric 3T magnetic resonance imaging (MRI) study using diffusion-weighted images (DWI) for the assessment of prostate cancer before and after radiotherapy (RT).

METHODS

A total of 34 patients, who received a histologic diagnosis of prostate adenocarcinoma, underwent MRI examination before and after local RT for the assessment of response to treatment. Apparent diffusion coefficient (ADC) values were calculated and compared.

RESULTS

Before RT, DWI shows pathologic restriction of signal, while after RT pathologic restriction of signal was reduced or disappeared. The ADC values were significantly increased after therapy (p&lt;0.05).

CONCLUSIONS

The use of DWI with ADC measurements may be an imaging biomarker in the assessment of prostate cancer.

Multiparametric MRI for recurrent prostate cancer post radical prostatectomy and postradiation therapy

The clinical suspicion of local recurrence of prostate cancer (PCa) after radical prostatectomy (RP) and after radiation therapy (RT) is based on the onset of biochemical failure. The aim of this paper was to review the current role of multiparametric-MRI (mp-MRI) in the detection of locoregional recurrence. A systematic literature search using the Medline and Cochrane Library databases was performed from January 1995 up to November 2013. Bibliographies of retrieved and review articles were also examined. Only those articles reporting complete data with clinical relevance for the present review were selected. This review article is divided into two major parts: the first one considers the role of mp-MRI in the detection of PCa local recurrence after RP; the second part provides an insight about the impact of mp-MRI in the depiction of locoregional recurrence after RT (interstitial or external beam). Published data indicate an emerging role for mp-MRI in the detection and localization of locally recurrent PCa both after RP and RT which represents an information of paramount importance to perform focal salvage treatments.

Metabolic atrophy and 3-T 1H-magnetic resonance spectroscopy correlation after radiation therapy for prostate cancer

OBJECTIVE

To correlate 3-T magnetic resonance spectroscopic imaging (MRSI) with prostate-specific antigen (PSA) levels in patients with prostate cancer treated with external beam radiation therapy to assess the potential advantages of MRSI.

MATERIALS AND METHODS

A total of 50 patients (age range 65-83 years) underwent PSA and MRSI surveillance before and at 3, 6, 12, 18 and 24 months after radiotherapy.

RESULTS

Of the 50 patients examined, 13 patients completely responded to therapy showing metabolic atrophy (MA), defined as a choline-plus-creatine/citrate (CC/C) ratio <0.2, at 3 months; in this group none had biochemical relapse (PSA nadir + 2 ng/mL) by the end of the follow-up. Of the 50 patients, 35 showed a partial response to therapy (CC/C ratio between 0.2 and 0.8) at 3 and 6 months and, of these 35 patients, 30 reached MA at 12 months, while five developed a recurrence (CC/C ratio >0.8). Three of those patients with recurrence had a biochemical relapse at 18 months and the other two at 24 months. Two of the 50 patients did not respond to the treatment, showing persistent disease from the 3rd month (CC/C ratio >0.8); one patient had biochemical relapse at 6 and the other at 12 months.

CONCLUSIONS

MRSI was shown to have a greater potential than PSA level in monitoring patients after radiotherapy, because it anticipates PSA nadir, and biochemical relapse in particular.

Prostate-specific antigen kinetics under androgen deprivation therapy and prostate cancer prognosis

OBJECTIVES

To compare the difference in characteristics of post-treatment prostate-specific antigen (PSA) kinetics among respective patients and their influence on disease prognosis.

METHODS

A cohort of totally 332 eligible patients with histologically confirmed and hormonally naïve prostate cancer, identified from the patients' database of Huashan Hospital, all received combined androgen deprivation therapy including bilateral orchiectomy or luteinizing hormone-releasing hormone antagonists with the oral administration of flutamide 250 mg t.i.d. All patients had their serum PSA level tested at least every 3 months in the first 2 years and at least once a half year from the third year on. PSA nadir, time to PSA nadir (TTPN), PSA normalization (<4 ng/ml), undetectable PSA level (<0.2 ng/ml), biochemical failure, overall survival and cancer-specific survival were analyzed.

RESULTS

PSA normalization, TTPN, and reaching the undetectable PSA level perhaps were the independent risk factors for predicting the three types of prognosis. Probably the best cut-off of PSA nadir was 0.2 ng/ml (sensitivity 65.7%, specificity 80.6%) and the best cut-off of TTPN was 10 months (sensitivity 71.6%, specificity 63.9%).

CONCLUSIONS

These results implied that a lower level of PSA nadir and longer TTPN can predict a better disease prognosis.

Multiparametric prostate MR imaging with T2-weighted, diffusion-weighted, and dynamic contrast-enhanced sequences: are all pulse sequences necessary to detect locally recurrent prostate cancer after radiation therapy?

PURPOSE

To compare diagnostic accuracy of T2-weighted magnetic resonance (MR) imaging with that of multiparametric (MP) MR imaging combining T2-weighted imaging with diffusion-weighted (DW) MR imaging, dynamic contrast material-enhanced (DCE) MR imaging, or both in the detection of locally recurrent prostate cancer (PCa) after radiation therapy (RT).

MATERIALS AND METHODS

This retrospective HIPAA-compliant study was approved by the institutional review board; informed consent was waived. Fifty-three men (median age, 70 years) suspected of having post-RT recurrence of PCa underwent MP MR imaging, including DW and DCE sequences, within 6 months after biopsy. Two readers independently evaluated the likelihood of PCa with a five-point scale for T2-weighted imaging alone, T2-weighted imaging with DW imaging, T2-weighted imaging with DCE imaging, and T2-weighted imaging with DW and DCE imaging, with at least a 4-week interval between evaluations. Areas under the receiver operating characteristic curve (AUC) were calculated. Interreader agreement was assessed, and quantitative parameters (apparent diffusion coefficient [ADC], volume transfer constant [K(trans)], and rate constant [k(ep)]) were assessed at sextant- and patient-based levels with generalized estimating equations and the Wilcoxon rank sum test, respectively.

RESULTS

At biopsy, recurrence was present in 35 (66%) of 53 patients. In detection of recurrent PCa, T2-weighted imaging with DW imaging yielded higher AUCs (reader 1, 0.79-0.86; reader 2, 0.75-0.81) than T2-weighted imaging alone (reader 1, 0.63-0.67; reader 2, 0.46-0.49 [P ≤ .014 for all]). DCE sequences did not contribute significant incremental value to T2-weighted imaging with DW imaging (reader 1, P > .99; reader 2, P = .35). Interreader agreement was higher for combinations of MP MR imaging than for T2-weighted imaging alone (κ = 0.34-0.63 vs κ = 0.17-0.20). Medians of quantitative parameters differed significantly (P < .0001 to P = .0233) between benign tissue and PCa (ADC, 1.64 × 10(-3) mm(2)/sec vs 1.13 × 10(-3) mm(2)/sec; K(trans), 0.16 min(-1) vs 0.33 min(-1); k(ep), 0.36 min(-1) vs 0.62 min(-1)).

CONCLUSION

MP MR imaging has greater accuracy in the detection of recurrent PCa after RT than T2-weighted imaging alone, with no additional benefit if DCE is added to T2-weighted imaging and DW imaging.

Biomarker-based targeting of the androgen-androgen receptor axis in advanced prostate cancer

Recent therapeutic advances for managing advanced prostate cancer include the successful targeting of the androgen-AR axis with several new drugs in castrate resistant prostate cancer including abiraterone acetate and enzalutamide (MDV3100). This translational progress from “bench to bed-side” has resulted in an enlarging repertoire of novel and traditional drug choices now available for use in advanced prostate cancer therapeutics, which has had a positive clinical impact in prolonging longevity and quality of life of advanced prostate cancer patients. In order to further the clinical utility of these drugs, development of predictive biomarkers guiding individual therapeutic choices remains an ongoing challenge. This paper will summarize the potential in developing predictive biomarkers based on the pathophysiology of the androgen-AR axis in tumor tissue from patients with advanced prostate cancer as well as inherited variation in the patient's genome. Specific examples of rational clinical trial designs incorporating potential predictive biomarkers from these pathways will illustrate several aspects of pharmacogenetic and pharmacogenomic predictive biomarker development in advanced prostate cancer therapeutics.

The basis for monitoring strategies in clinical guidelines: a case study of prostate-specific antigen for monitoring in prostate cancer

BACKGROUND

The volume of published literature on the evaluation and use of tests for monitoring purposes is sparse. Our aim was to determine the extent to which recommendations for monitoring prostate-specific antigen to detect recurrent prostate cancer consider key factors that should inform rule-based strategies for monitoring.

METHODS

We reviewed the recommendations made in clinical guidelines for the repeated measurement of prostate-specific antigen in men who have received primary treatment for localized prostate cancer. We assessed the guidelines using the Appraisal of Guidelines for Research and Evaluation Framework.

RESULTS

We identified guidelines and statements of best practice from nine organizations. We saw considerable inconsistency in recommendations for testing for prostate-specific antigen as a form of monitoring. Recommendations on when to test appeared to be almost exclusively determined using standard follow-up schedules rather than any scientific basis. Recommendations on when to take action were primarily based on consensus statements or retrospective case series. Eight of the nine guidelines acknowledged the potential presence of measurement variability, but they did not attempt to account for the effect of such variability on the interpretation of the results of tests for prostate-specific antigen. Many recommendations were made with few or no supporting references; however, a variety of papers were cited across guidelines. Of 48 papers cited, 29.1% (14/48) were reviews; the remaining 70.8% (34/48) of papers cited were primary studies.

INTERPRETATION

A systematic approach to the development of monitoring schedules using prostate-specific antigen in guidelines for prostate cancer is lacking, due to inadequacies in the available evidence and its use.

Serum efficacy biomarkers for oncology

Considerable interest has emerged in serum biomarkers that can be used to evaluate early effects of cancer therapeutics. Such efficacy biomarkers are expected to become valuable both for routine clinical care and for anticancer drug development. Here, we review the literature on serum efficacy biomarkers. We discuss how data using such markers can be interpreted, particularly with regard to the issue of specificity of different markers. An important question is whether biomarker response evaluation is expected to be congruent with evaluation by traditional anatomical methods. We argue that they may not be - biomarkers are expected to provide information with regard to induction of tumor cell death that will not necessarily reflect clinical outcome.

Assessment of response to radiotherapy for prostate cancer: value of diffusion-weighted MRI at 3 T

OBJECTIVE

The objective of our study was to investigate the changes of apparent diffusion coefficient (ADC) values in prostate cancers before and after radiotherapy at 3 T using a phased-array coil.

MATERIALS AND METHODS

Forty-nine patients with biopsy-proven prostate cancer who received radiotherapy underwent diffusion-weighted imaging (DWI) at 3 T and were included in the study. Biopsies in all patients were performed before the initial MRI examination (range, 15-35 days before MRI; mean, 23.4 days). All 49 patients underwent DWI (b values = 0 and 1,000 s/mm(2)) before and 1-5 months after the completion of radiotherapy. The changes in ADC values were measured for cancers and benign tissues before and after therapy. Additionally, the changes in serum prostate-specific antigen (PSA) levels were evaluated before and after therapy.

RESULTS

A total of 57 cancers (peripheral zone, n = 45; transition zone, n = 12) were found in 46 patients. For the tumors, the mean ADC value after therapy (1.61 x 10(-3) mm(2)/s) was increased compared with the mean ADC value before therapy (1.0 x 10(-3) mm(2)/s) (p < 0.001). After radiotherapy, the mean ADC values of benign peripheral zones and of benign transition zones were statistically significantly decreased compared with those before radiotherapy (p < 0.05). Before treatment, a significant difference of ADC values between the tumors and benign tissues was found (p < 0.001), whereas there was no significant difference of ADC values between them after treatment (p > 0.1). The median PSA level after therapy (0.49 ng/mL) was decreased compared with the median PSA level before therapy (20.0 ng/mL).

CONCLUSION

With the use of a 3-T MR scanner, our preliminary results suggest that ADC values may be useful as an imaging biomarker for monitoring therapeutic response of prostate cancer to radiotherapy.

New developments in the medical management of prostate cancer

Prostate cancer is a substantial public health burden and a leading cause of cancer-related morbidity and mortality in the United States despite the observation that annual prostate cancer-specific mortality rates have been declining during the previous decade. Although the reasons for this positive development are unclear, a combination of factors may have contributed. This update will review ongoing developments and summarize therapeutic advances in prostate cancer treatment on the basis of the current understanding of prostate cancer biology. Literature for this review was selected in 2009 by searching PubMed for the following keywords: prostatic neoplasms, castration, androgen receptor, hormonal, and chemotherapy. Emphasis is placed on published clinical studies in advanced prostate cancer therapeutics in the past 5 to 10 years. Also included in the review are novel hormonal agents targeting the androgen receptor currently in development for the treatment of advanced prostate cancer.

Why are pretreatment prostate-specific antigen levels and biochemical recurrence poor predictors of prostate cancer survival?

BACKGROUND

The value of pretreatment (initial) prostate-specific antigen (iPSA) and biochemical recurrence (BR) as prognostic factors for survival remains unclear. The authors sought to determine why using randomized trial data with 7-year minimum follow-up.

METHODS

In the Trans-Tasman Radiation Oncology Group 96.01 trial, 802 men with T2b, T2c, T3, or T4 N0 prostate cancer (PC) were randomized to radiotherapy alone or with 3 or 6 months neoadjuvant androgen deprivation between 1996 and 2000. Cox modeling was used to identify outcome predictors at follow-up landmark points.

RESULTS

Higher iPSA was found to be a potent predictor of BR-free survival (P < .01) but was not prognostic for prostate cancer-specific survival (PCSS) from randomization. Patients experiencing BR had unfavorable initial prognostic factors compared with patients who did not. After BR, these factors were not prognostic for PC death in models adjusted for time to BR (TTBR). In these models, TTBR predicted PCSS more satisfactorily than the occurrence of BR itself. Survival probability 5 years after BR exceeded 90% for men with TTBR >/=4 years; however, it dropped to 44% +/- 6% for men with TTBR <1 year. After BR, rapid PSA doubling time (DT), low iPSA, and short TTBR were identified as the most important predictors of inferior PCSS.

CONCLUSIONS

When BR occurs, prognostic factors for survival change. Low iPSA, short TTBR, and rapid PSA DT take over at this point, providing reasons why iPSA and occurrence of BR alone predict PCSS unsatisfactorily.

The decision-related psychosocial concerns of men with localised prostate cancer: targets for intervention and research

PURPOSE

To describe decision-related psychosocial issues relevant for men with clinically localised prostate cancer.

METHODS

Searches were conducted across three electronic databases to search the health and psychological literature for articles examining decision-related psychosocial issues for men with localised prostate cancer and their partners. Medline, PsycINFO and CINAHL databases were examined for the period from 1990 to December 2007.

RESULTS

Most men with localised prostate cancer want active involvement in decision-making. Difficulty in making the decision is common and decision-related distress may persist over time. Cancer-specific psychological distress (such as fear of recurrence but not overall anxiety) appears to be related to changes in PSA levels; and this distress influences treatment pathways. Decision support interventions are acceptable to men, improve knowledge and might reduce decision and cancer-related distress. However, the quality of intervention studies to date is low.

CONCLUSION

Clinicians should seek to involve men and their partners in treatment decision making concurrent with decision and psychological support. There is a need for high quality randomised control trials to identify the optimal approach to decision support for men with clinically localised prostate cancer.

Using extracellular biomarkers for monitoring efficacy of therapeutics in cancer patients: an update

Rapidly detectable and easily accessible markers of tumor cell death are needed for evaluating early therapeutic efficacy for immunotherapy and chemotherapy so that patients and their physicians can decide whether to remain with a given therapeutic strategy. Currently, image-based tests such as computed tomography scans and magnetic resonance imaging are used to visualize the response of a patient's tumor, but often these evaluations are not conducted for weeks to months after treatment begins. While serum levels of secreted proteins such as carcinoembryonic antigen and prostate specific antigen are commonly monitored to gauge tumor status during therapy and between image evaluations, the levels of these proteins do not always correlate well with the actual tumor response. In laboratory studies, it has been shown that tumor cells undergoing apoptosis can release cellular components into cell culture media such as cytochrome c, nucleosomes, cleaved cytokeratin-18 and E-cadherin. Studies of patient sera have found that these and other macromolecules can be found in circulation during cancer therapy, providing a potential source of material for monitoring treatment efficacy. In the future, analysis of biofluids from severe combined immunodeficiency mice bearing patient tumor specimens treated with a targeted therapy such as Apo2L/tumor necrosis factor-related apoptosis-inducing ligand will be useful in the preclinical identification of therapy response markers. In this review, the current status of the identification of serum markers of tumor cell apoptosis is provided, as well as a discussion of critical research questions that must be addressed and the considerations necessary when identifying a marker that reflects true clinical outcome.

Challenges of cancer biomarker profiling

OBJECTIVES

New biomarkers are being developed to identify individuals at risk for cancer, detect disease earlier, determine prognosis, detect recurrence, predict response to particular agents, and monitor response to treatment. This article attempts to address some of the challenges facing the research and medical communities in the delivery of new biomarkers for individualized medicine.

METHODS

A variety of issues and barriers can affect the transfer of clinical tests from research to clinical practice. Differences in sample collection, handling or storage, and profiling techniques may influence the protein profile obtained by any method.

RESULTS

Standard procedures and quality check schemes are necessary because there is a lack of definition to guarantee reproducibility of new procedures. From technical and economic viewpoints, the assay has to be sufficiently robust to be completed in community-based hospitals. Although traditionally cancer patients were treated with drugs of low toxicity or of high tolerance regardless of their efficacy in a given patient if the benefits of that drug are proven in both experimental and clinical conditions, recent advances have provided opportunities to adapt "tailored" treatment modalities. The evolving trend is the usage of patterns of markers instead of a single marker. Further challenges in biomarker development are in finding the relevant markers that have the right degree of specificity and sensitivity and a reliable test to measure the outcome.

CONCLUSIONS

Discovery, testing, and validation of clinically appropriate and commercially useful tumor markers should permit individualization of therapy.

Cytokeratin-18 is a useful serum biomarker for early determination of response of breast carcinomas to chemotherapy

PURPOSE

With a widening arsenal of cancer therapies available, it is important to develop therapy-specific predictive markers and methods to rapidly assess treatment efficacy. We here evaluated the use of cytokeratin-18 (CK18) as a serum biomarker for monitoring chemotherapy-induced cell death in breast cancer.

EXPERIMENTAL DESIGN

Different molecular forms of CK18 (caspase cleaved and total) were assessed by specific ELISA assays. Drug-induced release of CK18 was examined from breast carcinoma cells and tissue. CK18 protein composition was examined in serum. CK18 levels were determined in serum from 61 breast cancer patients during docetaxel or cyclophosphamide/epirubicin/5-fluorouracil (CEF) therapy.

RESULTS

Caspase-cleaved CK18 molecules were released from monolayer cultures and tumor organ cultures to the extracellular compartment. CK18 was present in complexes with other cytokeratins in serum. Such CK18 protein complexes are remarkably stable, leading to favorable performance of CK18 biomarker assays for clinical investigations. Docetaxel induced increased levels of caspase-cleaved CK18 in serum from breast cancer patients, indicating apoptosis. CEF therapy led to increases predominantly in uncleaved CK18, indicating induction of necrotic cell death in many tumors. The increase in total CK18 at 24 h of the first treatment cycle correlated to the clinical response to CEF therapy (P < 0.0001).

CONCLUSIONS

Induction of necrotic cell death may explain the clinical efficacy of anthracycline-based therapy for breast carcinomas with defective apoptosis pathways. We suggest that CK18 biomarkers are useful for early prediction of the response to CEF therapy in breast cancer and may be useful biomarkers for clinical trials.

SePaCS--a web-based application for classification of seroreactivity profiles

Immunogenic antigen sets possess high potential for minimally invasive disease detection and monitoring. For various diseases, including cancer, appropriate antigen sets have already been detected in blood sera of patients. Typically, a large number of sera from diseased and unaffected persons is screened for the antigens of interest. Sophisticated statistical learning approaches are trained on the resulting data set to classify sera as either tumor or normal sera. We developed a web-based application, called ‘Seroreactivity Profile Classification Service’ (SePaCS) that enables clinical groups to carry out analyzes of training sets and predictions of unclassified seroreactivity profiles with minimal effort. SePaCS provides a broad range of classification methods: four versions of a Naïve Bayes Classifier, Support Vector Machines with a radial basis function kernel, Linear Discriminant Analysis, and Diagonal Discriminant Analysis. The computed results are summarized in a PDF file. We demonstrate the functionality of SePaCS exemplarily for meningioma, a generally benign intracranial tumor. As a second example, we evaluated SePaCS on glioma, a malignant brain tumor. SePaCS is freely available at http://www.bioinf.uni-sb.de/sepacs.

Vaccination therapy in prostate cancer

Radical prostatectomy and radiation therapy provide excellent localized prostate cancer (PC) control. Although the majority of prostate carcinoma is nowadays diagnosed at early stages with favourable risk features, in patients up to 30-40% it recurs within 10 years. Furthermore, the lack of effective therapies, once prostate carcinoma becomes refractory to androgen deprivation, mandates the development of alternative therapeutic options. There is a growing interest in harnessing the potency and specificity of anti-tumour immunity through the generation of fully competent dendritic cells and tumour reactive effector lymphocytes. Several strategies to treat or prevent the development of metastatic PC have been explored in clinical trials and are summarized in this review, considering also the feasibility and safety of these approaches. In some cases clinical responses were achieved showing that vaccine-primed T cells induced anti-tumour activity in vivo. The present findings and perspectives of the immunologic interventions in PC patients will be discussed.

A minimally invasive multiple marker approach allows highly efficient detection of meningioma tumors

Background

The development of effective frameworks that permit an accurate diagnosis of tumors, especially in their early stages, remains a grand challenge in the field of bioinformatics. Our approach uses statistical learning techniques applied to multiple antigen tumor antigen markers utilizing the immune system as a very sensitive marker of molecular pathological processes. For validation purposes we choose the intracranial meningioma tumors as model system since they occur very frequently, are mostly benign, and are genetically stable.

Results

A total of 183 blood samples from 93 meningioma patients (WHO stages I-III) and 90 healthy controls were screened for seroreactivity with a set of 57 meningioma-associated antigens. We tested several established statistical learning methods on the resulting reactivity patterns using 10-fold cross validation. The best performance was achieved by Naïve Bayes Classifiers. With this classification method, our framework, called Minimally Invasive Multiple Marker (MIMM) approach, yielded a specificity of 96.2%, a sensitivity of 84.5%, and an accuracy of 90.3%, the respective area under the ROC curve was 0.957. Detailed analysis revealed that prediction performs particularly well on low-grade (WHO I) tumors, consistent with our goal of early stage tumor detection. For these tumors the best classification result with a specificity of 97.5%, a sensitivity of 91.3%, an accuracy of 95.6%, and an area under the ROC curve of 0.971 was achieved using a set of 12 antigen markers only. This antigen set was detected by a subset selection method based on Mutual Information. Remarkably, our study proves that the inclusion of non-specific antigens, detected not only in tumor but also in normal sera, increases the performance significantly, since non-specific antigens contribute additional diagnostic information.

Conclusion

Our approach offers the possibility to screen members of risk groups as a matter of routine such that tumors hopefully can be diagnosed immediately after their genesis. The early detection will finally result in a higher cure- and lower morbidity-rate.

Docetaxel induces apoptosis in hormone refractory prostate carcinomas during multiple treatment cycles

Caspase-cleaved proteins are released from disintegrated apoptotic cells and can be detected in the circulation. We here addressed whether caspase-cleaved cytokeratin 18 (CK18-Asp396) can be used as a serum biomarker for assessment of the clinical efficiency of chemotherapy in hormone-refractory prostate cancer (HRPC). A total of 82 patients with HRPC were evaluated during 751 treatment cycles, either with estramustine (EMP)/vinorelbine or with EMP/docetaxel. The levels of CK18-Asp396 and of total CK18 were measured in patient serum before and during therapy by ELISA. Docetaxel induced significant increases in serum CK18-Asp396 (P<0.0001) and total CK18 (P<0.0002), suggesting induction of apoptosis. Similarly, vinorelbine induced increases in both CK18-Asp396 and CK18 (P<0.001 and 0.011). In contrast, EMP induced increases in total serum CK18 (P<0.0001), but not in CK18-Asp396 (P=0.13). The amplitudes of docetaxel-induced increases were associated with baseline prostate-specific antigen (PSA) and CK18 serum levels in these patients, consistent with tumoral origin of caspase-cleaved fragments. Docetaxel induced significant increases in CK18-Asp396 during second-, third- and fourth-line therapy and induced increased levels of CK18-Asp396 during treatment cycles 1–8. In contrast, vinorelbine induced significant increases only during cycles 1–3. In a subgroup of 32 patients that received EMP/vinorelbine in second line followed by EMP/docetaxel in third line, docetaxel induced stronger increases than vinorelbine (P=0.008). These results show that the CK18-Asp396 serum marker can be used to assess tumour apoptosis in vivo and suggest that the clinical efficiency of docetaxel in HRPC is due to induction of apoptosis during multiple treatment cycles.

Prostate-specific antigen (PSA) alone is not an appropriate surrogate marker of long-term therapeutic benefit in prostate cancer trials

The prostate-specific antigen (PSA) is the most studied marker of prostate cancer. It is used for screening and as indicator of disease evolution for individual patients. PSA being a prognostic factor is however not sufficient to justify using PSA-derived endpoints as surrogate for definitive survival endpoint in phase III trials. First, we clarify the terminology and requirements for a marker to be a valid surrogate endpoint. We then review the published literature pertaining to the validation of PSA endpoints as surrogate in all disease stages. We discuss the limitations of these studies and conclude that so far, PSA is not a validated surrogate endpoint in any of the disease settings and treatment conditions considered. We give some recommendations for the planning of trials that would use PSA endpoints (in hormone refractory disease) and for the early stop of (endocrine treatment) trials on the basis of intermediate results based on PSA.

Survival of men with clinically localized prostate cancer treated with prostatectomy, brachytherapy, or no definitive treatment

BACKGROUND

The optimal treatment for men with early stage prostate cancer remains undefined. Survival of such patients after surgery, brachytherapy, or no definitive therapy was investigated specifically to determine the impact of age at diagnosis.

METHODS

In all, 60,290 men diagnosed with organ-confined, low and moderate grade prostate cancer between 1988 and 2002 were retrospectively identified from centers participating in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program. Prostate cancer-specific mortality (PCSM) and any-cause mortality (ACM) were determined. Outcomes for patients treated by brachytherapy, surgery, or receiving no definitive treatment were compared using the Wilcoxon test, stratified by T-stage and grade, and using multivariate analysis.

RESULTS

The median follow-up time was 46 months (range, 0-189 months). For men under age 60 at diagnosis, PCSM at 10 years was 1.3%, 0.5%, and 3.7% for surgery, brachytherapy, and no definitive therapy, respectively. For men age 60 and older the PCSM was 3.8%, 5.3%, and 8.4%, respectively. On univariate and multivariate analysis, surgery and brachytherapy resulted in statistically equivalent PCSM and ACM, and both had a significantly lower PCSM and ACM versus no definitive therapy.

CONCLUSIONS

A better survival was observed in men treated with a definitive therapy. The magnitude of the benefit on PCSM or ACM was similar for both definitive therapies irrespective of age.

Pomegranate fruit juice for chemoprevention and chemotherapy of prostate cancer

Prostate cancer is the most common invasive malignancy and the second leading cause of cancer-related deaths among U.S. males, with a similar trend in many Western countries. One approach to control this malignancy is its prevention through the use of agents present in diet consumed by humans. Pomegranate from the tree Punica granatum possesses strong antioxidant and antiinflammatory properties. We recently showed that pomegranate fruit extract (PFE) possesses remarkable antitumor-promoting effects in mouse skin. In this study, employing human prostate cancer cells, we evaluated the antiproliferative and proapoptotic properties of PFE. PFE (10-100 microg/ml; 48 h) treatment of highly aggressive human prostate cancer PC3 cells resulted in a dose-dependent inhibition of cell growth/cell viability and induction of apoptosis. Immunoblot analysis revealed that PFE treatment of PC3 cells resulted in (i) induction of Bax and Bak (proapoptotic); (ii) down-regulation of Bcl-X(L) and Bcl-2 (antiapoptotic); (iii) induction of WAF1/p21 and KIP1/p27; (iv) a decrease in cyclins D1, D2, and E; and (v) a decrease in cyclin-dependent kinase (cdk) 2, cdk4, and cdk6 expression. These data establish the involvement of the cyclin kinase inhibitor-cyclin-cdk network during the antiproliferative effects of PFE. Oral administration of PFE (0.1% and 0.2%, wt/vol) to athymic nude mice implanted with androgen-sensitive CWR22Rnu1 cells resulted in a significant inhibition in tumor growth concomitant with a significant decrease in serum prostate-specific antigen levels. We suggest that pomegranate juice may have cancer-chemopreventive as well as cancer-chemotherapeutic effects against prostate cancer in humans.

A rational approach to androgen therapy for hypogonadal men with prostate cancer

With earlier detection and improved survival from early stage prostate cancer, it is likely that the numbers of men presenting with hypogonadal symptoms following curative surgery for their cancer will increase. Although testosterone supplementation is effective in improving symptoms of hypogonadism, traditionally such therapy has been contraindicated in patients who have had prostate cancer. This paper reviews the evidence that testosterone therapy can be safely given to selected men with hypogonadism who have had prostate cancer but currently have no evidence of disease by clinical and prostate-specific antigen (PSA) criteria. Such patients should be treated cautiously and followed closely.