Prostate-specific mRNA detection in whole blood as an analytically validated prognostic biomarker for patients with castration-resistant prostate cancer (CRPC).

45 Background: To estimate the association between molecular biomarkers and outcomes, robust assays are needed before qualification in prospective trials. Although tumor specific transcripts detected in blood by PCR have been associated with outcome, an analytically validated PCR platform enabling detection of CTC-associated transcripts in clinical settings remains to be identified. Here we explore detecting a panel of prostate specific transcripts in conjunction with conventional markers in CRPC. Methods: Blood was collected from 97 patients with progressive CRPC in PAXgene tubes (2.5 ml) for total RNA extraction. Five genes expressed in prostate but not in nucleated blood cells were analyzed by primer-specific RT-PCR. Fluidigm Dynamic Array platform was analytically validated for KLK3, KLK2, HOXB13, GHRL2 and FOXA1 assays. Each PCR-reaction was run in 6 replicates, detection thresholds for each gene were chosen by ROC analysis of an independent set of 56 CRPC patients versus 51 healthy volunteers, and r...