Abstract: PD65-07
Sources of Funding: Cleveland Diagnostics, Inc.

Introduction

We provide interim evaluation of a multivariate model centered on IsoPSA^TM, a novel structure-focused protein biomarker, to assess potential discrimination of high-grade (Gleason≥7) from benign or low-grade (Gleason=6) patients. In this multicenter prospective trial we provide performance data compared with biopsy reports.

Methods

226 plasma samples were obtained from multiple clinical sites, collected within 30 days prior to prostate biopsy from patients with blood PSA between 2 and 44 ng/ml. IsoPSA^TM was evaluated against 12 core TRUS biopsy results as the gold standard comparator. The prevalence of high-grade patients in the sample cohort was 33.2%. Multivariate logistic regression model included only the IsoPSA^TM test parameter, K, and age.

Results

The model predictions are subdivided into low risk with high NPV, medium risk, and high risk with high PPV. The overall ROC analysis for IsoPSA^TM showed an AUC=0.82. For the low risk cohort, with the previously determined value of the test statistic, KP<15%, we note very high NPV=96%. Conversely, patients with KP>64% are at high risk, with PPV=79%. In comparison, serum PSA ROC analysis showed AUC=0.67, NPV=85%, PPV=36%, at PSA=4.0. Current standard selection practice resulted in 67% negative biopsies. Using IsoPSA^TM KP for patient selection would have resulted in 96% avoided biopsies for the low risk cohort, while improving biopsy yield to 79% at the high risk cohort.

Conclusions

Combining only IsoPSA^TM with patient age allows for clinically actionable stratification of patients into low and high risk cohorts to improve patient selection for biopsy.

Funding

Cleveland Diagnostics, Inc.