Evaluation of a new, rapid, qualitative, one-step PSA Test for prostate cancer screening: the PSA RapidScreen test

The "Bloodless" Blood Test: Intradermal Prick Nanoelectronics for the Blood Extraction-Free Multiplex Detection of Protein Biomarkers

Protein biomarkers' detection is of utmost importance for preventive medicine and early detection of illnesses. Today, their detection relies entirely on clinical tests consisting of painful, invasive extraction of large volumes of venous blood; time-consuming postextraction sample manipulation procedures; and mostly label-based complex detection approaches. Here, we report on a point-of-care (POC) diagnosis paradigm based on the application of intradermal finger prick-based electronic nanosensors arrays for protein biomarkers' direct detection and quantification down to the sub-pM range, without the need for blood extraction and sample manipulation steps. The nanobioelectronic array performs biomarker sensing by a rapid intradermal prick-based sampling of proteins biomarkers directly from the capillary blood pool accumulating at the site of the microneedle puncture, requiring only 2 min and less than one microliter of a blood sample for a complete analysis. A 1 mm long microneedle element was optimal in allowing for pain-free dermal sampling with a 100% success rate of reaching and rupturing dermis capillaries. Current common micromachining processes and top-down fabrication techniques allow the nanobioelectronic sensor arrays to provide accurate and reliable clinical diagnostic results using multiple sensing elements in each microneedle and all-in-one direct and label-free multiplex biomarkers detection. Preliminary successful clinical studies performed on human volunteers demonstrated the ability of our intradermal, in-skin, blood extraction-free detection platform to accurately detect protein biomarkers as a plausible POC detection for future replacement of today's invasive clinical blood tests. This approach can be readily extended in the future to detect other clinically relevant circulating biomarkers, such as miRNAs, free-DNAs, exosomes, and small metabolites.

Activity-Based Diagnostics: Recent Advances in the Development of Probes for Use with Diverse Detection Modalities

Abnormal enzyme expression and activity is a hallmark of many diseases. Activity-based diagnostics are a class of chemical probes that aim to leverage this dysregulated metabolic signature to produce a detectable signal specific to diseased tissue. In this Review, we highlight recent methodologies employed in activity-based diagnostics that provide exquisite signal sensitivity and specificity in complex biological systems for multiple disease states. We divide these examples based upon their unique signal readout modalities and highlight those that have advanced into clinical trials.

Evaluation of a rapid one-step PSA test for primary prostate cancer screening

BACKGROUND

To enhance the convenience and reduce the cost of prostate cancer (PC) screening, a one-step prostate-specific antigen (PSA) test was evaluated in a large population. The PSA SPOT test kit enables rapid detection of human PSA in serum or plasma at or above a cutoff level of 4 ng/mL to aid in the diagnosis of PC.

METHODS

PC screening using the PSA SPOT test was offered to male participants in educational public lectures that we conducted in various cities. Test results were reported to participants at the end of the lectures. Blood samples from 1429 men were evaluated. Two independent observers interpreted the tests at 15 and 30 min. The remaining serum samples were subsequently tested using a conventional quantitative assay.

RESULTS

The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the test were 79.9, 93.0, 65.4, 96.6, and 91.2%, respectively. The sensitivity and specificity of the test changed with variations in the reading time. Quantitative assessment of the intensity of the band was correlated with the PSA value.

CONCLUSIONS

PSA testing using this kit can be easily performed. The low cost and speed of the test make it a useful and convenient tool for primary PC screening.

Claros System: A Rapid Microfluidics-Based Point-of-Care System for Quantitative Prostate Specific Antigen Analysis from Finger-Stick Blood

INTRODUCTION

Determination of circulating prostate specific antigen (PSA) is commonly used in the diagnosis and treatment monitoring of prostate cancer [1]. Presently, PSA testing is performed in centralized laboratories, which is associated with prolonged time between venipuncture and the PSA value being available. In this prospective study, we present a new and rapid test system for the quantitative determination of PSA levels from finger-stick blood.

METHODS

The Claros1^® analyzer is a rapid microfluidics-based point-of-care system for quantitative PSA analysis from 10-µl finger-stick blood that requires only 10 min for testing. Total PSA concentrations by the Claros system in 100 consecutive asymptomatic men (median age 57 years, range 44-81 years) were compared with two commercially available, commonly used PSA assays (Abbott and Elecsys by Roche) performed by a reference laboratory.

RESULTS

Eighty-six percent of finger-stick blood-borne probes from 100 men were evaluable for PSA testing by the Claros1^® analyzer system. In 13/14 cases the expiry date of the microfluid cassettes of the Claros system was exceeded and one blood puncture was performed inadequately. The correlations between the Claros results and OPKO-Abbott and OPKO-Roche assay results were high, with R² values of 0.982 and 0.985, respectively. The R² value for the Roche-Abbott correlation was 0.991 with a slope value of 1.160. Prostate cancer was diagnosed in seven cases, with a median PSA of 1.8 ng/ml in the Claros group compared to 1.75 ng/ml and 2.1 ng/ml in the Abbott and Roche groups, respectively.

CONCLUSION

The Claros1^® PSA assay combines the advantages of rapid, accurate detection with a low required sample volume, allowing the analysis to be performed using finger-stick blood. Provided that further analysis proves the reproducibility of the test, it may help to reduce the number of office visits, thus decreasing costs to the health care system.

Current Trends in Ligand Binding Real-Time Measurement Technologies

Numerous advances in ligand binding assay (LBA) real-time measurement technologies have been made within the last several years, ranging from the development of novel platforms to drive technology expansion to the adaptation of existing platforms to optimize performance and throughput. In this review, we have chosen to focus on technologies that provide increased value to two distinct segments of the LBA community. First, experimentally, by measuring real-time binding events, these technologies provide data that can be used to interrogate receptor/ligand binding interactions. While overall the platforms are not new, they have made significant advances in throughput, multiplexing, and/or sensitivity. Second, clinically, these point-of-care (POC) technologies provide instantaneous information which facilitates rapid treatment decisions.

Assessment of a new point-of-care system for detection of prostate specific antigen

Background

Measurement of the prostate specific antigen (PSA) remains an important tool in prostate cancer (PC) diagnosis. Due to limited availability of laboratory devices in an outpatient setting, compact and easy-to-handle point-of-care (POC) systems are desirable. Recently, a chip for PSA measurement on the concile® Ω100 POC reader platform was introduced. To investigate the clinical applicability, we evaluated the system in a consecutive cohort of patients undergoing PSA measurement in our outpatient clinic.

Methods

Between 07/2014 and 01/2015, PSA was analyzed in a total of 198 patients by the POC reader system and in parallel by an Immulite 2000® and Centaur® standard laboratory system, respectively. By standard (Immulite®) measurement, 67 (34,2 %) had PSA > 4 ng/ml and 131 (65,8 %) had PSA ≤ 4 ng/ml. Results were correlated by linear regression analyses for all patients and within PSA subgroups. For patients with available prostate histology after PSA measurement (n = 68), receiver-operating characteristic curves were created and area under the curve (AUC), sensitivity and specificity for the prediction of PC at best cut-off value were calculated.

Results

The coefficients of determination (r²) for the POC device compared to laboratory testing were 0.72 (Immulite®) and 0.63 (Centaur®), respectively (both p < 0.0001). In the PSA range of ≤4 ng/ml, the observed correlations were 0.75 and 0.70, respectively. For the POC test system, AUC for detection of PC was calculated with 0.745 while the standard laboratory tests showed 0.778 (Immulite®) and 0.771 (Centaur®). At best cut-off of 3.64 ng/ml, PSA analysis by the POC system showed a sensitivity of 85.7 % and a specificity of 66.7 %.

Conclusions

The POC system obtained good concordance to elaborate laboratory measurement. In a screening scenario, the system provides quick and reliable PSA measurement, especially in the PSA range up to 4 ng/ml.

Evaluation of a rapid quantitative determination method of PSA concentration with gold immunochromatographic strips

BACKGROUND

Prostate cancer remains the most common cancer in men. Qualitative or semi-quantitative immunochromatographic measurements of prostate specific antigen (PSA) have been shown to be simple, noninvasive and feasible. The aim of this study was to evaluate an optimized gold immunochromatographic strip device for the detection of PSA, in which the results can be analysed using a Chromogenic Rapid Test Reader to quantitatively assess the test results.

METHODS

This reader measures the reflectance of the signal line via a charge-coupled device camera. For quantitative analysis, PSA concentration was computed via a calibration equation. Capillary blood samples from 305 men were evaluated, and two independent observers interpreted the test results after 12 min. Blood samples were also collected and tested with a conventional quantitative assay.

RESULTS

Sensitivity, specificity, positive and negative predictive values, and accuracy of the PSA rapid quantitative test system were 100, 96.6, 89.5, 100, and 97.4 %, respectively. Reproducibility of the test was 99.2, and interobserver variation was 8 % with a false positive rate of 3.4 %. The correlation coefficient between the ordinary quantitative assay and the rapid quantitative test was 0.960.

CONCLUSIONS

The PSA rapid quantitative test system provided results quickly and was easy to use, so that tests using this system can be easily performed at outpatient clinics or elsewhere. This system may also be useful for initial cancer screening and for point-of-care testing, because results can be obtained within 12 min and at a cost lower than that of conventional quantitative assays.

A low-cost, high-performance system for fluorescence lateral flow assays

We demonstrate a fluorescence lateral flow system that has excellent sensitivity and wide dynamic range. The illumination system utilizes an LED, plastic lenses and plastic and colored glass filters for the excitation and emission light. Images are collected on an iPhone 4. Several fluorescent dyes with long Stokes shifts were evaluated for their signal and nonspecific binding in lateral flow. A wide range of values for the ratio of signal to nonspecific binding was found, from 50 for R-phycoerythrin (R-PE) to 0.15 for Brilliant Violet 605. The long Stokes shift of R-PE allowed the use of inexpensive plastic filters rather than costly interference filters to block the LED light. Fluorescence detection with R-PE and absorbance detection with colloidal gold were directly compared in lateral flow using biotinylated bovine serum albumen (BSA) as the analyte. Fluorescence provided linear data over a range of 0.4–4,000 ng/mL with a 1,000-fold signal change while colloidal gold provided non-linear data over a range of 16–4,000 ng/mL with a 10-fold signal change. A comparison using human chorionic gonadotropin (hCG) as the analyte showed a similar advantage in the fluorescent system. We believe our inexpensive yet high-performance platform will be useful for providing quantitative and sensitive detection in a point-of-care setting.

Evaluation of a modified lateral flow immunoassay for detection of high-sensitivity cardiac troponin I and myoglobin

We prospectively evaluated the use of lateral flow immunoassay (LFIA) test modified with nanoparticles for combined detection of high-sensitivity cardiac troponin I (hs-cTnI) and myoglobin with the aim of excluding acute myocardial infarction (AMI). Specimens from 173 patients with symptoms suggestive of AMI were collected to measure hs-cTnI and myoglobin using an electrochemiluminescence immunoassay (ECLI) and the LFIA test modified with nanoparticles, and a comparison was performed between the modified method and a commercial LFIA test for detection of the two proteins. The accuracy of the modified LFIA test was also evaluated. Consistent agreement was observed in the quantitative comparison of 173 clinical samples using the modified LFIA and ECLI, and the modified method was more sensitive than the commercial LFIA test. The accuracy of the modified LFIA was <12% for both hs-cTnI and myoglobin. Thus, the new approach has great potential to improve LFIAs test, demonstrating its usefulness for simple screening applications and for sensitivity and quantitative immunoassays for diagnosis ofAMI.

Do "rapid" PSA assays reduce anxiety and stress of prostate cancer patients undergoing regular review? A prospective evaluation

OBJECTIVES

Waiting for prostate-specific antigen (PSA) results may create anxiety for patients. Recently developed "rapid" PSA assays have become available, which achieve laboratory sensitivity and specificity. The manufacturers claim these assays will help to reduce anxiety associated with PSA testing. The aim of this study was to test the hypothesis that rapid received PSA results reduce patient anxiety.

METHODS

One hundred eighty-eight (n = 188) patients participated in a prospective randomized study. After obtaining informed consent, 67 patients were assigned to receive PSA results within 15 minutes of the blood sample being drawn, facilitating a discussion with the physician while in-clinic. One hundred twenty-one (n = 121) patients were assigned to receive their results within 1 to 4 days by telephone. Patients completed a baseline questionnaire about PSA testing and a follow-up questionnaire after they had received their PSA result by either method.

RESULTS

There were no significant differences in patient demographics between the "rapid" and "delayed" PSA test groups. Baseline measurements of stress and anxiety were low and not significantly different between the groups. Receiving a rapid PSA result did not significantly reduce stress and anxiety compared with a delayed result. However, 89% of patients receiving a rapid result would elect to have this method again.

CONCLUSIONS

The rapid PSA test did not prove to alleviate stress or anxiety associated with receiving results. However, the cohort assigned to the rapid PSA test would prefer to have their results rapidly to facilitate discussion regarding their future management.

Development of a lateral flow assay for rapid detection of bovine antibody to Anaplasma marginale

A rapid lateral flow assay for detection of bovine antibody to Anaplasma marginale was developed. The assay used a recombinant peptide of major surface protein 5 as the antigen and a monoclonal antibody specific for bovine IgG(1) conjugated with colloidal gold beads for detection. Serum and anticoagulated blood samples were obtained from cattle in an area where anaplasmosis was endemic. The samples were selected based on positive identification of the organism in blood smears. The unclotted blood samples were used for PCR determination of the presence of A. marginale while the sera were tested by a commercial competitive enzyme immunoassay (CELISA) and by the lateral flow assay (LFA). Similar samples, collected at a Canadian sales barn, were tested by the CELISA and LFA and 10% were tested by PCR for the presence of A. marginale nucleic acid. In addition, stored serum samples from a second endemic area were tested by CELISA and LFA. Of the 114 smear positive samples, all were positive by CELISA and LFA. All samples were also positive by PCR. Samples from Canadian sources (n=524) were negative in the CELISA but 11 sera gave false positive reactions in the LFA. All samples tested were PCR negative. Of 113 samples from herds with anaplasmosis, 53 were positive in the CELISA and 50 were LFA positive.