Urine Exosome RNA Predicts High-Grade Prostate Cancer at Initial Biopsy - Beyond the Abstract

Prostate cancer (PC) remains the most commonly diagnosed cancer in men and the second cause of cancer-related death in the United States. PSA and the digital rectal exam remain the most widely used methods for early detection; however, neither are reliable to discriminate Grade Group 2 and higher PC (high-grade PC, HGPC) from benign pathology or more indolent Grade Group 1 cancers. This continues to result in a high proportion of men who are subjected to procedures such as surgery, radiation, and annual prostate biopsies as part of an active surveillance program.

Approximately 7 years ago in collaboration with the Prostate Cancer Foundation, we embarked on an investigative approach to develop a non-invasive, DRE-independent urine test (i.e. the ExoDx Prostate test, or “EPI”) predicting the likelihood of clinically significant PCa (GG2 or higher) from benign and or GG1 in men presenting for their initial biopsy with an equivocal PSA of 2-10 mg/mL. The EPI test is a liquid biopsy that quantifies three RNA targets in urine exosomes. Importantly, the performance of the test is independent of all clinical variables which allow for the urologist to introduce other parameters including obesity, underlying genetics, and race. This feature also differentiates the EPI test from other assays predicting HGPC including 4K (Opko Diagnostics, Florida) and Select MDX (MDX Health, Irvine, CA). Our primary objective was to refine and personalize the biopsy decision process, stratifying patients into lower or higher risk for HGPC in a population where PSA and other clinical variables are nondiscriminatory.

As reported in the current abstract from Prostate Cancer and Prostatic Diseases publication, the EPI test has been extensively validated in three independent prospective studies representing over 1212 men from greater than 23 community practices and 4 academic medical centers in the United States. As reported in the current pooled meta-analysis, (Margolis et al, Prostate Cancer Prostatic Dis, 2021), the EPI test remained consistently robust and more effective than PSA, and various online risk calculators such as the Prostate Cancer Prevention Trial (PCPT) and the European Randomized Study of Screening for Prostate Cancer (ERSPC) in guiding the prostate needle biopsy decision process. The results further support that increasing the EPI score (above 20) increases the probability for finding HGPC with a 50% probability at an EPI score greater than 50.

Written by: Michael J. Donovan PhD, MD, University of Miami, Miami, Florida

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