Abstract: PNFLBA-15
Sources of Funding: Private

Introduction

Overdetection and overtreatment of indolent prostate cancer (PCa) remains a significant health issue requiring noninvasive assays to guide the prostate biopsy decision process. We previously demonstrated that a non-DRE urine exosome gene expression assay (ExoDx Prostate (IntelliScore) (EPI) discriminates GS 7 PCa from GS 6 and benign disease, potentially reducing the number of unnecessary biopsies. We initiated a novel prospective, phase-adaptive two cohort trial design: Group 1 (G1), men scheduled for a biopsy and Group 2 (G2), men for which the decision to biopsy is uncertain. The G1 consensus results including EPI cut-point recommendation will be applied to G2 patients with clinical utility, ease of adoption, patient response and health economic data collected. Here we report interim results from G1 with initial cut-point comparison to the original validation trial._x000D_ _x000D_

Methods

The trial was activated on Sept. 2016 at 9 sites (8 community practice, 1 academic), geographically distributed across the U.S. We plan to enlist up to 20 sites by April 2017. Enrollment is limited to initial biopsy patients only, >/=50 years with PSA 2-10 ng/mL. The EPI test is performed at Exosome Diagnostics’ CLIA laboratory in Cambridge, MA; G1 results are collected for consensus review and G2 recommendation.

Results

The average biopsy rate across all sites is 1-2 / week. Demographics of the 96 (of targeted) 500 G1 patients enrolled thus far are comparable to the validation study (mean age 64 years, mean PSA 5.78; 75% white, 17% African American, 23% positive family history of PCa, 81% non-suspicious DRE). Of note, we have observed a higher positive biopsy rate of 59% (vs. 47% in validation study); 22% ISUP 1 (GS 3+3) and 37% >/=ISUP 2. The EPI test validated (15.6) vs. adjusted (20) cut-points both result in NPV 90, with sensitivity of 94% and 92%, respectively. The number of avoided biopsies is greater (30%) with the adjusted cut-point of 20 vs. the original validated cut-point (21%); while missing only 1>/=ISUP 3 case. The original validated cut-point would have avoided biopsies in 30% of men with GS6 or benign disease while the adjusted cut-point would have avoided 43% of biopsies in this population.

Conclusions

Interim results from a prospective adaptive trial of the EPI test demonstrate consistent performance as identified in the original validation study. The adjusted cut-point continues to provide added benefit without risk of missing significant disease.

Funding

Private