Evaluation of an Epigenetic Assay for Predicting Repeat Prostate Biopsy Outcome in African American Men

Abstract OBJECTIVES To evaluate an epigenetic assay performed on tissue from negative prostate biopsies in a group of African American (AA) men undergoing repeat biopsy, and to compare accuracy for predicting repeat biopsy outcome to prior studies conducted in predominantly Caucasian populations. METHODS The study population consisted of 211 AA men from seven urology centers across the U.S., all of whom were undergoing 12-core trans-rectal ultrasound guided repeat biopsy within 30 months from a negative index biopsy. All biopsy cores from the negative index biopsy were profiled for the epigenetic biomarkers GSTP1, APC and RASSF1 using ConfirmMDx for Prostate Cancer. RESULTS Upon repeat biopsy, 130/211 (62%) subjects had no prostate cancer (PCa) detected and 81/211 (38%) were diagnosed with PCa. Of the subjects with PCa, 54/81 (67%) were diagnosed with Gleason Score (GS) ≤ 6 PCa and 27/81 (33%) with GS ≥7 disease. For detection of PCa at repeat biopsy, ConfirmMDx sensitivity was 74.1% and specificity 60.0%, equivalent to prior studies (P=0.235 and 0.697, respectively). For detection of GS ≥ 7 PCa, sensitivity was 78% and specificity 53%. The negative predictive values for detection of all PCa and GS ≥ 7 PCa were 78.8% and 94.2%, respectively. CONCLUSIONS In this group of AA men, we successfully validated an epigenetic assay to assess the need for repeat biopsy. Results were consistent with previous studies from predominantly Caucasian populations. Therefore, the ConfirmMDx assay is a useful tool for risk stratification of AA men who had an initial negative biopsy.