Clinical utility study of confirms mdx for prostate cancer in a community urology practice.

Abstract

94 Background: There is an unmet need for methods to better identify patients most likely to benefit from repeat prostate biopsy after an initial negative biopsy. ConfirmMDx is a molecular test clinically validated for detection of prostate cancer (PCa) in tissue from PCa-negative biopsies. In this clinical utility study, we evaluated the impact of ConfirmMDx on the management of patients being considered for repeat prostate biopsy in a community urology practice. Methods: The study population consisted of 605 men with a prior PCa-negative prostate biopsy, who were counseled on the need to undergo repeat biopsy at a large community urology practice due to persistent elevated risk of PCa. All tissue cores from each PCa-negative patient were tested with the ConfirmMDx methylation-specific PCR test, and positive or negative ConfirmMDx results based on the presence or absence of GSTP1, APC or RASSF1 methylation in the biopsy tissue. ConfirmMDx results were provided to the physician for use in repeat biopsy decision-making. Medical record review was conducted at a minimum of nine months after ConfirmMDx results were reported. Results: Of the 605 subjects enrolled, 308 (51%) had a negative ConfirmMDx test result and 297 (49%) were positive. For the entire study population, average age was 64 (median 64, interquartile range 59 to 69), average serum PSA level 6.8 ng/mL (5.7, 4.3 to 8.1). The median follow-up for both Confirm positives and negatives was 10 months post-testing. Repeat biopsy rates for ConfirmMDx positive and negative men were 32.3% (96/297) and 5.8% (15/308), respectively (P < 0.001). For patients who received a biopsy during the follow-up period, the time between ConfirmMDx and repeat biopsy was shorter for ConfirmMDx positive men versus ConfirmMDx negatives (median 4 vs. 8 months, P = 0.007). Conclusions: In this utility study, ConfirmMDx had a significant impact on repeat prostate biopsy decision-making in a U.S. community urology setting. Repeat biopsy rates in ConfirmMDx positive men were six-fold higher than in ConfirmMDx negatives. These results reflect the clinical utility of ConfirmMDx for biopsy decision-making in real world clinical practice.