Validation of a two-gene mRNA urine test for detection of high-grade prostate cancer in German men.

96 Background: There is an unmet need for non-invasive methods that can accurately identify patients at increased risk for clinically significant prostate cancer (PCa). SelectMDx is a urine-based molecular test that has been clinically validated for the detection of high-grade PCa. We evaluated SelectMDx clinical performance in a cohort of German men undergoing initial prostate biopsy. Methods: The study population consisted of 443 men sequentially enrolled men who underwent initial prostate biopsy between July 2009 and December 2014 due to suspected PCa. Post-DRE urine was collected from all subjects prior to biopsy, and samples stored at -70C. Urinary HOXC6 and DLX-1 mRNAs were quantified by PCR in May 2018, and RNA results combined with clinical risk factors to determine the likelihood that biopsy would identify ISUP grade group (GG) ≥ 2 (Gleason Score ≥ 7) PCa. We assessed SelectMDx performance for detection of GG ≥ 2 PCa, compared to the PCPT Risk Calculator Version 2.0 (PCPTRC, http://myprostatecancerrisk.com , accessed Oct 7, 2018). Results: For the 443 subjects enrolled, average age was 66 years (median 66, interquartile range 61 to 71), and average serum PSA level 8.8 ng/mL (6.4, 4.8 to 9.7). Cancer was detected in 243/443 (55%) men biopsied (43% GG1, 36% GG2, 9% GG3 and 12% GG4-5). The prevalence of GG2-5 PCa in this population was 31.4% (139/443). For detection of GG2 or higher PCa versus GG1 or no PCa at biopsy, SelectMDx AUC was 0.82 (95% C.I. 0.78-0.86) and the PCPTRC yielded AUC 0.75 (0.70-0.80), P < 0.001. SelectMDx sensitivity was 94% (89-98%), specificity 46% (40-52%), positive predictive value 45% (42-47%) and negative predictive value (NPV) 95% (90-97%). If the initial biopsy had been performed based on SelectMDx results alone, 46% of potentially unnecessary biopsies and 34% of all biopsies would have been avoided, while 5.8% of men with biopsy-detectable high-grade PCa (seven GG2, one GG3) may have had their diagnosis delayed. Conclusions: In this first validation study of SelectMDx in German men, the test’s clinical performance was comparable to the published EU validation study, showing a high NPV for detection of GG2 or higher PCa. These results provide further evidence for the clinical validity of SelectMDx.