Reflex PCA3 mRNA Testing: Validation of Post-Biopsy Urine Sample and Correlation with Prostate Biopsy Findings in ~2000 Patients. 1 1 1 1 1 2 3 1 Jeffrey G. Brown *, John R. Fulmer , Javier Romano , John Pownell , Wayne Rigler , Amery Wirtshafter , Mark Sarno , Scott B. Shappell 1 2 3 Avero Diagnostics, Irving, TX; Urology Center of Florida, Miami, FL; Vision Biotechnology Consulting, Encinitas, CA BACKGROUND PSA · Serum test widely used for detecting prostate cancer · Lacks adequate specificity, resulting in large numbers of negative prostate biopsies (bxs) · Men with elevated PSA and one or more negative bxs represent a management dilemma PCA3 · Urine-based molecular test that measures PCA3 and PSA mRNA in whole urine · Validated for urine specimens collected after “attentive DRE” · Improved specificity compared to PSA when correlated to subsequent bx results · May be useful in facilitating repeat bx decisions in men with elevated PSA and negative initial bx · Such test use with post-DRE collection requires return visit to urologist (following negative prostate bx) FIGURES RESULTS • Mean/median age: 66/66 (range 39-91) (n=1909) • Mean/median PSA : 6.7/5.1 ng/ml (n=1794) PSA <2.50 ng/ml (n=148 (8.3 %)) PSA 2.50 – 10.00 ng/ml (n=1404 (78.3 %)) PSA > 10.00 ng/ml (n=242 (13.5 %)) • Mean/median number of cores (concurrent biopsy) 12/12 • PCA3 test informative in 1887 (98.8%) • Correlation between PSA and post-bx void PCA3 score was significant, but only minimal - (Pearson 0.0785; Spearman Rho 0.0919). Mean/median PCA3 scores • Bx was benign in 970 (50.8%), CaP in 726 (38%), HGPIN in 124 (6.5%), atypical in 89 (4.7%) - “Negative” includes benign, HGPIN, and Atypical unless otherwise stated) 66.7 58.9 49.8 44.5 26.9 14.8 Figure One: Comparison of PCA3 and PSA ROC’s (n=1724 available pairs) PCA3 AUC = 0.700 (0.676-0.724) p<0.0001 PSA AUC = 0.564 (0.536-0.591) p<0.0001 AUC Difference = 0.136 (0.101-0.171) p<0.0001 Figure Two: Biopsy CaP by PCA3 score range COMMENTS: • Optimal PCA3 score cutoff was 21.7, with 65% sensitivity and 65% specificity OBJECTIVES • CaP risk increased with progressively higher PCA3 score ranges (Figure Two) · Collection of urine at the time of TRUS-guided bx represents a novel approach for performing PCA3 testing. · PCA3 is then performed as a “reflex” test for patients with a negative biopsy. • Performance of PCA3 test was similar for men with no prior bx compared to men with at least one prior non-positive bx (Figure Three) · The objectives of this study were: · To validate the use of post-bx urine for PCA3 testing · To correlate post-bx void PCA3 scores with concurrent biopsy results and compare to performance of PSA. MATERIALS & METHODS · 2015 men (July 2008 to July 2010) had urine collected immediately following TRUS-guided prostate bx. · Excluded from the study were: · Men with history of CaP (n=73) · Men with bxs of < 6 cores (n=3) or ≥ 24 cores (n=4) · Men with PSA ≥ 50 ng/ml (n=28) (100 % with CaP on bx) · Final n=1909 men with prostate bx and post-bx voided urine specimen · PCA3 and PSA mRNA were quantitated with a laboratory developed test using transcription-mediated amplification (Gen-Probe, Inc.). 3 · A PCA3 score (PCA3/PSA mRNA x 10) ≥ 35 was considered positive Figure Three: PCA3 ROC in Men Without and With Prior Bx: Overlap indicates no significant difference (AUC 0.716; n=633/1058, no previous bx; AUC 0.702, n=425/1058, prior non-positive bx) • Univariate OR is significant for all PSAs, PSA 2.5-10.0, and PSA > 10.0 (not significant for smaller number of men in PSA <2.5 category (95% CIs overlap 1.0)). • In multivariate logistic regression including PSA, PCA3 is significant either as a continuous marker or as a categorical marker with cutpoint at 35. • PCA3 AUC is significantly greater than PSA AUC (p<0.0001) for all PSAs, PSA 2.5-10.0, and PSA > 10.0 (for PSA <2.5 ng/ml, analysis yields marginal diagnostic value; 95% CI of AUC overlaps 0.500 but p=0.0354). (See Figure One.) CONCLUSIONS The performance of the PCA3 test for predicting CaP on concurrent bx was essentially the same (similar or higher AUC) as noted in multicenter trials using post-DRE urine. • Post-bx urine is a valid sample for PCA3 testing and presents an efficient way to apply reflex PCA3 testing. • Patients with a negative bx and negative reflex PCA3 test may be followed more conservatively. • Men with a negative bx and an elevated PCA3 score on reflex PCA3 test may be at increased risk for subsequent CaP detection on bx, impacting follow-up. • With this testing approach, for men with a positive bx the PCA3 score is available for potential use in prognostication. • Future expanded repeat bx data incorporating multi-variable risk predictors should allow for optimization of PCA3 testing for improved repeat bx decisions.