No abstract

e22038 Background: PSA tests have low specificity, which frequently results in unnecessary biopsy and typically limits screening to patients with PSA values >4.0 ng/mL. The investigational ProCaM assay detects CpG island methylation within the promoter regions of three markers (GSTP1, RARß2, and APC) that are indicative of the presence of prostate cancer. The objective of this research study was to assess assay testing reproducibility and lot-to-lot variability. Methods: Assay reproducibility: 8 operators from 4 external clinical laboratories tested a panel comprised of a negative panel member (NM2C5 cells) for the internal control (ß-Actin), a high positive and low positive panel members (LNCaP cells) for all 3 markers and ß-Actin. Variability of assay results based on marker cycle threshold (Ct) values was determined. Lot variability: 3 unique lots of the ProCaM Test Kit were evaluated on DNA extracted from 169 post-DRE urine samples to show reproducibility across kit lots. Urine samples were collected from consenting subjects that were scheduled for prostate biopsy and tested by 3 operators at the same facility. Results: Assay reproducibility: The informative rate was 98% (766 valid results of 782 total tests). The overall intersite %CV and SD values for Cts were = 9.2% and 1.49%, respectively. The percent agreement with qualitative (positive/negative) outcome for High, Low, and Negative panel members was = 98% for GSTP1, RARß2, APC, and ß-Actin. Lot variability: Of the 169 biopsy results a histology positivity rate of 39% (66/169) was shown. Urine sample results for these samples showed that the areas under the curve for the 3 unique ProCaM Test Kit lots were equivalent (0.72, 0.74, 0.75, p > 0.263). Using the result categories of negative and positive with identical cutoffs for GSTP1, RARß2, APC for samples with >5 ssDNA copies 98% concordance was observed for all 3 lots evaluated. Conclusions: The investigational assay produces a qualitative result without the requirement for normalization or sample dilution and requires only one reaction per patient sample. Current results demonstrate that the assay has a high informative test rate and that results are reproducible across sites, operators runs, and kit lots. [Table: see text]