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Development of a Multiplexed Urine Assay for Prostate Cancer Diagnosis

¹ Veridex LLC, a Johnson & Johnson company, Warren, NJ; ² Arkansas Urology, Little Rock, AR; ³ Mayo Validation Support Services, Rochester, MN; ⁴ Pacific Rim Pathology Medical Corporation, San Diego, CA; ⁵ Medical University of Innsbruck, Department of Urology, Innsbruck, Austria; ⁶ Medical University of Innsbruck, Department of Pathology, Innsbruck, Austria; ⁷ Medical University of Graz, Department of Urology, Graz, Austria; ⁸ Medical University of Graz, Department of Pathology, Graz, Austria; ⁹ Oridis-Biomed GmbH, Graz, Austria.

^aAddress correspondence to this author at: Veridex LLC, a Johnson & Johnson company, 33 Technology Drive, Warren, NJ 07059. Fax 908-791-2430; e-mail amazumde{at}vrxus.jnj.com.

Background: Several studies have demonstrated the value of DNA methylation in urine-based assays for prostate cancer diagnosis. However, a multicenter validation with a clinical prototype has not been published.

Methods: We developed a multiplexed, quantitative methylation-specific polymerase chain reaction (MSP) assay consisting of 3 methylation markers, GSTP1, RARB, and APC, and an endogenous control, ACTB, in a closed-tube, homogeneous assay format. We tested this format with urine samples collected after digital rectal examination from 234 patients with prostate-specific antigen (PSA) concentrations 2.5 µg/L in 2 independent patient cohorts from 9 clinical sites.

Results: In the first cohort of 121 patients, we demonstrated 55% sensitivity and 80% specificity, with area under the curve (AUC) 0.69. In the second independent cohort of 113 patients, we found a comparable sensitivity of 53% and specificity of 76% (AUC 0.65). In the first cohort, as well as in a combined cohort, the MSP assay in conjunction with total PSA, digital rectal examination status, and age improved the AUC without MSP, although the difference was not statistically significant. Importantly, the GSTP1 cycle threshold value demonstrated a good correlation (R = 0.84) with the number of cores found to contain prostate cancer or premalignant lesions on biopsy. Moreover, samples that exhibited methylation for either GSTP1 or RARB typically contained higher tumor volumes at prostatectomy than those samples that did not exhibit methylation.

Conclusions: These data confirm and extend previously reported studies and demonstrate the performance of a clinical prototype assay that should aid urologists in identifying men who should undergo biopsy.