Prospective clinical study of a prostate cancer (PCa) rule-out blood test for PSA gray zone patients using a sensitive circulating tumor cell assay.

143Background: The diagnostic confirmation of prostate cancer in patients with a PSA in the gray zone (4–10 ng/ml) is controversial, often leading to unnecessary biopsies. The sensitivity of the PSA test at a 4 ng/mL cut-off can be as low as 21%. We introduce a new test for prostate cancer detection in PSA gray zone patients, with the potential to decrease the number of unnecessary prostate biopsies. Methods: A single-center, multi-year, IRB-approved, prospective, blinded clinical study was conducted in 200 high-risk subjects. 4 mL of blood was drawn and processed for CTC analysis using the CellMax biomimetic platform (CMx). The CMx CTC test uses a proprietary microfluidic biochip that accurately captures and enumerates CTCs with antibodies to EpCAM, CK18 and PSMA. All patients underwent routine screening including PSA and digital rectal exam (DRE). Gray zone and those diagnosed as ‘diseased’ based on PSA & DRE also underwent a biopsy. Multivariate generalized linear models incorporating CMx test results ...