Clinical Validation of IsoPSA™, a Single Parameter, Structure Based Assay for Improved Detection of High Grade Prostate Cancer.

PURPOSE: Current prostate specific antigen markers to detect prostate cancer are limited by low specificity for high grade disease. IsoPSA™ is a blood based, structure focused assay which predicts risk by partitioning the isoforms of prostate specific antigen that are linked to cancer in an aqueous 2-phase reagent system. We validated the clinical performance of this assay for identifying high grade disease in a new contemporary biopsy cohort. MATERIALS AND METHODS: We performed a multicenter prospective validation in 271 men scheduled for prostate biopsy at a total of 7 academic and community centers who were enrolled between May 2017 and March 2018. Blood samples were obtained for assay prior to biopsy. The discrimination power of the assay to detect high grade prostate cancer (Gleason 7 or greater) was evaluated by ROC analysis and compared to prior results. Clinical performance was further improved by comparison with multiparametric magnetic resonance imaging-ultrasound vs transrectal ultrasound guided biopsies. RESULTS: The assay AUC was 0.784 for high grade vs low grade cancer/benign histology, which was superior to the AUCs of total prostate specific antigen and percent free prostate specific antigen. If 1,000 patients were biopsied, the assay would have reduced the number of unnecessary biopsies from 705 to 402 (43%) with only 22 missed high grade cancers, of which 7 would have been Gleason sum 4 + 3 or higher. Subset analysis of multiparametric magnetic resonance imaging guided biopsy produced a substantial improvement of the AUC to 0.831. CONCLUSIONS: Validation of the structure based IsoPSA assay demonstrated statistical concordance with previously reported results and verified its superior performance vs concentration based prostate specific antigen and the free-to-total prostate specific antigen ratio. The assay improvement in detecting high grade prostate cancer using multiparametric magnetic resonance imaging-ultrasound guided biopsy may help define a new diagnostic paradigm.

IsoPSA Performance Characteristics are Unaffected by 5-Alpha Reductase Inhibitors or Alpha-Blockers: Results From the IsoPSA Validation Study.

OBJECTIVE: To. determine the impact of 5-α reductase inhibitors or α-blockers on IsoPSA performance for the detection of actionable prostate cancer. MATERIALS AND METHODS: This is a secondary analysis of data from an institutional review board approved, prospective, multicenter(8-sites) study evaluating IsoPSA in men ≥ 50 years of age with a total PSA ≥ 4 ng/mL with planned prostate biopsy who met previously described inclusion and exclusion criteria. Analytic groups included (i)all subjects, (ii-iii)+/- 5-ARI use, (iv-v)+/- α-blocker use. The performance characteristics of IsoPSA in these groups were assessed by ROC curve, sensitivity, and specificity (SP) analysis. RESULTS: A total of 1385 men were recruited with 888 men included in final analysis. Actionable prostate cancer, defined as GG2+, was identified in a total of 316 patients with 40 and 217 patients reporting 5-ARI and α-blocker use respectively. Sensitivity to detect both prostate cancer and actionable cancer was similar between patient subsets (P >.05). SP was similar between patients regardless of 5-ARI(P >.05). Increased SP was noted in patients on α-blockers(GG1+: No-α-blocker: 0.360 vs α-blocker: 0.529, P <.05; GG2+: No-α-blocker: 0.40 vs α-blocker: 0.61, P <.05). ROC analysis demonstrates that IsoPSA performance is unaffected by 5-ARI or α-blocker use for prostate cancer and actionable cancer (GG2+) detection. CONCLUSION: The performance of IsoPSA for detecting any prostate cancer and clinically actionable prostate cancer is unaffected by commonly used medications (5-ARI and α-blockers) for symptoms of benign prostatic hyperplasia.

Clinical validation of IsoPSA, a single parameter, structure-focused assay for improved detection of prostate cancer: A prospective, multicenter study.

BACKGROUND: IsoPSA is a blood-based test that assesses prostate cancer (CaP) risk by partitioning and detecting cancer-specific structural isoforms of prostate specific antigen (PSA) with an aqueous 2- phase system. OBJECTIVE: To validate the diagnostic performance of IsoPSA for High-Grade CaP and Any CaP risk on biopsy in men age ≥ 50 with total PSA ≥ 4 ng/ml. DESIGN, SETTING, AND PARTICIPANTS: Prospective, multicenter study of 888 men scheduled for prostate biopsy at 8 academic and community sites between August 2015 and August 2020. INTERVENTION: IsoPSA test. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Receiver operating characteristic and likelihood ratio analysis used to validate diagnostic performance for previously established IsoPSA Index cutoffs for High-Grade CaP (Gleason Score ≥ 7) and Any CaP (Gleason Score ≥ 6), compare IsoPSA to total PSA and % free PSA, and evaluate subgroups (total PSA 4-10 ng/ml, total PSA > 10 ng/ml, biopsy naïve, prior negative biopsy). RESULTS AND LIMITATIONS: The disease prevalence was 35.6% (High-Grade CaP) and 58.9% (Any CaP). The area under the receiver operating characteristic curve was 0.783 (High-Grade CaP) and 0.770 (Any CaP). IsoPSA outperformed total PSA and % free PSA on area under the receiver operating characteristic curve, specificity, positive and negative predictive value at similar sensitivity. Using selected IsoPSA Index cutoffs, an estimated 46% (High-Grade CaP) and 42% (Any CaP) of biopsies could be avoided in low-risk patients. IsoPSA displayed statistically informative likelihood ratio-based predictive characteristics. IsoPSA maintained accuracy in clinically relevant subgroups. CONCLUSIONS: IsoPSA diagnostic performance and predictive value is validated for High-Grade CaP and Any CaP in men age ≥ 50 with total PSA ≥ 4 ng/ml undergoing diagnostic biopsy. IsoPSA outperforms total and % free PSA in discriminating the risk of prostate cancer on biopsy. PATIENT SUMMARY: IsoPSA has the potential to reduce unnecessary biopsies and improve the risk-benefit ratio for CaP early detection.

IsoPSA® Reduces Provider Recommendations for Biopsy and Magnetic Resonance Imaging in Men with Total Prostate Specific Antigen ≥4 ng/ml: A Real-World Observational Clinical Utility Study.

INTRODUCTION: We assessed the impact of the IsoPSA® test for prostate cancer risk assessment on provider patient management decisions in a real-world clinical setting. METHODS: A total of 38 providers, including advanced practice providers, fellowship trained oncologists and general urologists in the Cleveland Clinic health system including both community-based practices and academic locations, enrolled 900 men being evaluated for prostate cancer; 734 met inclusion criteria (age ≥50 years, total serum prostate specific antigen [PSA] ≥4 and <100 ng/ml and no history of prostate cancer) and IsoPSA indication for use. A standard template was used to document biopsy recommendation prior to and after receiving IsoPSA results. The primary outcome was the number of biopsy and magnetic resonance imaging recommendation changes occurring after IsoPSA testing. RESULTS: IsoPSA testing resulted in a 55% (284 vs 638) net reduction in recommendations for prostate biopsy for men with total PSA ≥4 ng/ml. Additionally, a 9% reduction in recommendations for magnetic resonance imaging was observed. There was strong concordance between IsoPSA results and provider recommendations for prostate biopsy, with 87% of patients with an IsoPSA index above the threshold recommended for biopsy and 92% of patients with an IsoPSA index below the threshold not recommended for biopsy. CONCLUSIONS: In a real-world clinical setting, providers from diverse training backgrounds and practice settings readily adopted IsoPSA with substantial reductions in the rate of recommended prostate biopsies in patients with elevated PSA values (≥4 ng/ml). There was a high concordance between recommendation for or against prostate biopsy and the IsoPSA result.

Exploratory analysis of kinetic solubility measurements of a small molecule library.

Kinetic solubility measurements using prototypical assay buffer conditions are presented for a ∼58,000 member library of small molecules. Analyses of the data based upon physical and calculated properties of each individual molecule were performed and resulting trends were considered in the context of commonly held opinions of how physicochemical properties influence aqueous solubility. We further analyze the data using a decision tree model for solubility prediction and via a multi-dimensional assessment of physicochemical relationships to solubility in the context of specific 'rule-breakers' relative to common dogma. The role of solubility as a determinant of assay outcome is also considered based upon each compound's cross-assay activity score for a collection of publicly available screening results. Further, the role of solubility as a governing factor for colloidal aggregation formation within a specified assay setting is examined and considered as a possible cause of a high cross-assay activity score. The results of this solubility profile should aid chemists during library design and optimization efforts and represent a useful training set for computational solubility prediction.

The Single-parameter, Structure-based IsoPSA Assay Demonstrates Improved Diagnostic Accuracy for Detection of Any Prostate Cancer and High-grade Prostate Cancer Compared to a Concentration-based Assay of Total Prostate-specific Antigen: A Preliminary Report.

BACKGROUND: IsoPSA is a serum-based assay that predicts prostate cancer (PCa) risk by partitioning isoforms of prostate-specific antigen (PSA) with an aqueous two-phase reagent. OBJECTIVES: To determine the diagnostic accuracy of IsoPSA in identifying the presence or absence of PCa and the presence of high-grade disease in a contemporary biopsy cohort. DESIGN, SETTING, AND PARTICIPANTS: Multicenter prospective study of 261 men scheduled for prostate biopsy at five academic and community centers in the USA enrolled between August 2015 and December 2016. INTERVENTION: Performance of the IsoPSA assay. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Discrimination power was evaluated using receiver operating characteristic (ROC) analysis. The outcome of the IsoPSA assay was transformed into risk probability using logistic regression. Decision curve analysis (DCA) was used to compare the net benefit of IsoPSA against other clinical protocols. RESULTS AND LIMITATIONS: The overall prevalence was 53% for any PCa and 34% for high-grade PCa. The area under the ROC curve was 0.79 for any cancer versus none and 0.81 for high-grade PCa versus low-grade PCa/benign histology. In this preliminary study, DCA revealed a superior net benefit of IsoPSA against no biopsy, all biopsy, and the modified Prostate Cancer Prevention Trial Risk Calculator 2.0. At a cutoff selected to recommend biopsy, IsoPSA demonstrated a 48% reduction in false-positive biopsies; at a cutoff selected to identity men at low risk of high-grade disease, there was a 45% reduction in the false-positive rate. CONCLUSION: The structure-based IsoPSA assay outperformed concentration-based PSA measurement, and provided a net benefit against other protocols. Once validated, clinical use of IsoPSA could significantly reduce unnecessary biopsies while identifying patients needing treatment. PATIENT SUMMARY: The IsoPSA assay outperformed prostate-specific antigen in predicting the overall risk of prostate cancer and the risk of clinically significant cancer in a preliminary study. The IsoPSA assay could assist in determining the need for prostate biopsy for patients.

Chemiluminescent nitrogen detection (CLND) to measure kinetic aqueous solubility.

Solubility is the dose-limiting property for in vitro studies, and therefore is a critical physicochemical property to measure in drug discovery. Solubility data can be used to guide lead optimization, troubleshoot erratic bioassay results, and identify potential downstream liabilities such as insufficient solubility for bioassays or oral bioavailability. Typically, early in vitro studies are performed using library compounds prepared as dimethylsulfoxide (DMSO) stock solutions, resulting in in vitro test solutions containing DMSO at low concentration (<5% v/v). Since DMSO can affect the apparent solubility, it is desirable to obtain solubility data under conditions mimicking the in vitro study. Kinetic solubility (from DMSO stock solutions) is often preferred over thermodynamic solubility (from dry powder) in early drug discovery. The protocols in this article describe a general procedure for assessing kinetic aqueous solubility of early drug discovery compounds using a miniaturized shake flask method with chemiluminescent nitrogen detection (CLND).