Elena Critselis

Developing proteomic biomarkers for bladder cancer: towards clinical application

Clinical use of proteomic biomarkers has the potential to substantially improve the outcomes of patients with bladder cancer. An unmet clinical need evidently exists for noninvasive biomarkers, which might enable improvements in both the diagnosis and prognosis of patients with bladder cancer, as well as improved monitoring of patients for the presence of recurrence. Urine is considered the optimal noninvasive source of proteomic biomarkers in patients with bladder cancer. Currently, a number of single-protein biomarkers have been detected in urine and tissue using a variety of proteomic techniques, each having specific conceptual considerations and technical implications. Promising preclinical data are available for several of these proteins; however, the combination of single urinary proteins into multimarker panels might better encompass the molecular heterogeneity of bladder cancer within this patient population, and prove more effective in clinical use.

Utility of the CKD273 peptide classifier in predicting chronic kidney disease progression

BACKGROUND Chronic kidney disease (CKD) is a growing public health concern, afflicting approximately one-tenth of adults in developed countries. However, the clinical need for an accurate test, such as a biomarker and/or peptide classifier, for predicting CKD progression and related adverse outcomes remains unaddressed. Recently, a proteomics approach based on capillary electrophoresis-mass spectrometry was employed to develop a urinary peptide-based high-dimensional classifier, namely CKD273, for predicting CKD progression. OBJECTIVES The study aims to critically appraise the evidence level of the CKD273 classifiers utility in predicting CKD progression, according to the Oxford Evidence-Based Medicine (EBM) and Strength of Recommendation Taxonomy (SORT) guidelines. METHODS Eligible studies were identified by a literature search of MEDLINE and Web of Science Expanded Core Collection databases. Limitations were set to prospective cohort studies evaluating the classifiers accuracy in predicting CKD progression. Data extraction was undertaken according to a predefined protocol by two independent reviewers. The EBM and SORT guidelines were applied to appraise the CKD273 classifiers utility for predicting CKD progression. RESULTS The query search results rendered four prospective cohort studies. The classifier performed independently of age, gender and the type of urine storage containers used. The classifier predicted the development of micro- or macroalbuminuria and rapid decline (i.e. >-5% annual decrease) in the estimated glomerular filtration rate. One study assessed the association of the classifier with end-stage renal disease and death but did not take confounding factors into account. The CKD273 classifier attained high evidence levels according to the EBM (score range 1b), supporting its utility for predicting CKD progression. However, lower scores were attained when the studies were scored according the SORT guidelines (score ranges 1-4). CONCLUSIONS Initial promising evidence supports the CKD273 classifiers utility in predicting CKD progression. The classifiers applicability should be corroborated with additional evidence arising from inception cohort studies assessing patient-oriented outcomes, which demonstrate its added value beyond currently available clinical risk predictors, as well as its cost-effectiveness in clinical practice.

Epidemiologic Design and Analysis for Proteomic Studies: A Primer on -Omic Technologies

Proteome analysis is increasingly being used in investigations elucidating the molecular basis of disease, identifying diagnostic and prognostic markers, and ultimately improving patient care. We appraised the current status of proteomic investigations using human samples, including the state of the art in proteomic technologies, from sample preparation to data evaluation approaches, as well as key epidemiologic, statistical, and translational issues. We systematically reviewed the most highly cited clinical proteomic studies published between January 2009 and March 2014 that included a minimum of 100 samples, as well as strategies that have been successfully implemented to enhance the translational relevance of proteomic investigations. Limited comparability between studies and lack of specification of biomarker context of use are frequently observed. Nevertheless, there are initial examples of successful biomarker discovery in cross-sectional studies followed by validation in high-risk longitudinal cohorts. Translational potential is currently hindered, as limitations in proteomic investigations are not accounted for. Interdisciplinary communication between proteomics experts, basic researchers, epidemiologists, and clinicians, an orchestrated assimilation of required resources, and a more systematic translational outlook for accumulation of evidence may augment the public health impact of proteomic investigations.

Development and validation of urine-based peptide biomarker panels for detecting bladder cancer in a multi-center study

Purpose: Urothelial bladder cancer presents high recurrence rates, mandating continuous monitoring via invasive cystoscopy. The development of noninvasive tests for disease diagnosis and surveillance remains an unmet clinical need. In this study, validation of two urine-based biomarker panels for detecting primary and recurrent urothelial bladder cancer was conducted. Experimental Design: Two studies (total n = 1,357) were performed for detecting primary (n = 721) and relapsed urothelial bladder cancer (n = 636). Cystoscopy was applied for detecting urothelial bladder cancer, while patients negative for recurrence had follow-up for at least one year to exclude presence of an undetected tumor at the time of sampling. Capillary electrophoresis coupled to mass spectrometry (CE-MS) was employed for the identification of urinary peptide biomarkers. The candidate urine–based peptide biomarker panels were derived from nested cross-sectional studies in primary (n = 451) and recurrent (n = 425) urothelial bladder cancer. Results: Two biomarker panels were developed on the basis of 116 and 106 peptide biomarkers using support vector machine algorithms. Validation of the urine-based biomarker panels in independent validation sets, resulted in AUC values of 0.87 and 0.75 for detecting primary (n = 270) and recurrent urothelial bladder cancer (n = 211), respectively. At the optimal threshold, the classifier for detecting primary urothelial bladder cancer exhibited 91% sensitivity and 68% specificity, while the classifier for recurrence demonstrated 87% sensitivity and 51% specificity. Particularly for patients undergoing surveillance, improved performance was achieved when combining the urine-based panel with cytology (AUC = 0.87). Conclusions: The developed urine-based peptide biomarker panel for detecting primary urothelial bladder cancer exhibits good performance. Combination of the urine-based panel and cytology resulted in improved performance for detecting disease recurrence. Clin Cancer Res; 22(16); 4077–86. ©2016 AACR.

Cost-effectiveness of screening type 2 diabetes patients for chronic kidney disease progression with the CKD273 urinary peptide classifier as compared to urinary albumin excretion

Background In type 2 diabetes mellitus (T2DM) patients, chronic kidney disease (CKD) progression may occur without detectable changes in urinary albumin excretion (UAE) rate. A new urinary peptide classifier (CKD273) has exhibited greater ability to detect CKD progression, however, its cost-effectiveness remains unknown. This study evaluated the cost-effectiveness of screening for CKD progression with the CKD273 classifier, as compared to UAE, in diabetic patients. Methods A decision-analytic Markov model was developed to estimate costs and health outcomes [including overall survival and quality-adjusted life years (QALYs)] from a health system perspective for adopting a new annual screening strategy based on the CKD273 classifier as compared to annual UAE-based screening in a hypothetical cohort of T2DM patients. High-risk patients were defined as T2DM patients with at least one concomitant risk factor (i.e. patients with background genetic risk for developing the disease, obesity, hypertension and/or smoking history) for developing diabetic nephropathy secondary to cardiovascular disease (CVD)-related complications. Low-risk T2DM patients, were defined as those not having any of the aforementioned concomitant risk factors. Results Over the projected course of a patients lifetime, in all T2DM patients annual screening with the CKD273 classifier was more costly, but also more effective, than annual screening with UAE. The incremental costs incurred with screening based on the CKD273 classifier were €3,053 per patient, while patients gained 0.13 QALYs. Hence, in all patients, annual screening with the CKD273 classifier was cost effective [incremental cost-effectiveness ratio (ICER) €23,903/QALY gained], notably below current government thresholds for funding such health care interventions. For patients at high risk of developing diabetic nephropathy secondary to CVD-related complications, screening based on the CKD273 classifier was cost-saving (i.e. dominant, being both more effective and less expensive than UAE-based screening). Finally, in low-risk patients, CKD273 classifier-based screening was not cost effective (ICER €73,140/QALY) given current government willingness-to-pay thresholds. Conclusions In diabetic patients, annual CKD273 classifier-based screening is more costly but also more effective in QALYs gained as compared to UAE. From a health provider perspective, the observed benefits are greatest when such screening is implemented in patients at high risk for diabetes-associated renal or cardiovascular diseases (CVDs).

Chloride Intracellular Channel 4 Overexpression in the Proximal Tubules of Kidneys from the Spontaneously Hypertensive Rat: Insight from Proteomic Analysis

Background: Hypertensive nephropathy, a leading cause of declining kidney function, is a multifactorial process not well understood. In order to elucidate biological processes and identify novel macromolecular components crucially involved in the process of kidney damage, the application of system biology approaches, like proteomics, is required. Methods: Proteomic studies were performed using the renal parenchyma of spontaneously hypertensive rats (SHR) and their normotensive Wistar Kyoto controls. Animals were sacrificed at early time intervals (6, 13, and 20 weeks after birth), the renal tissue extract was subjected to two-dimensional gel electrophoresis, differential expressed proteins were identified, and altered pathways were evaluated. One specific protein, chloride intracellular channel 4 (CLIC4), not implicated so far in the development of hypertension and nephrosclerosis, was further studied by Western blotting, immunohistochemistry and immunofluorescence. Results: Proteomic analysis identified several pathways/processes and organelles (mitochondria) as being affected from the early stages of hypertension. CLIC4 was overexpressed in SHR at all 3 time intervals examined. This finding was confirmed by Western blotting and by immunohistochemistry and immunofluorescence; these morphological techniques demonstrated that CLIC4 was almost exclusively localized at the apical surface of the proximal tubular epithelial cells. Conclusions: Our studies provide evidence that major changes occur in the renal parenchyma from early stages of the development of hypertension. The overexpression of CLIC4 suggests that alterations in the proximal tubular compartment during hypertension should be further examined and that CLIC4 may be a useful early marker of renal tubular alterations due to elevated blood pressure.

Epidemiology, Energy Balance and Prostate Cancer Incidence and Mortality

Energy balance is defined as the equilibrium between energy consumed and expended. A substantial number of prospective epidemiological studies have been conducted to investigate the association of obesity and physical activity with risk of prostate cancer. The aim of this chapter is to provide an overall review and critical appraisal of the literature on these two purported risk factors and prostate cancer incidence overall, incidence of advanced and non-advanced disease, and prostate cancer mortality. Markers of general and central obesity have been associated with an increased risk of advanced and fatal disease, and a decreased risk of localized prostate cancer, but hints of bias were identified in this literature. The literature evidence is sparse and inconsistent for other adiposity indices and physical activity. Future prospective studies and large consortia with valid and direct assessment of the time-varying nature of body fatness and physical activity and with a focus on lethal prostate cancer are needed to draw firmer conclusions.