Platelets harbor prostate cancer biomarkers and the ability to predict therapeutic response in castration-resistant patients.

e583Background: Novel therapies for castration resistant prostate cancer (CRPC) have been introduced in the clinic with possibilities for individualized treatment plans. Best practice of those expensive drugs requires predictive biomarker monitoring. This study used circulating biomarker analysis to follow cancer-derived transcripts implicated in therapy resistance. Methods: The isolated platelet population of blood samples and QRT-PCR were used to identify selected biomarker transcripts in patients with CRPC prior chemo- or androgen synthesis directed therapies. The association between biomarker status in platelets (positive vs. negative) and therapy response, progression-free survival (PFS) and overall survival (OS) was examined. Results: Fifty patients received either docetaxel (n = 24) or abiraterone (n = 26) therapy, with therapy response rates of 54% and 48%, respectively. Transcripts for the PC-associated biomarkers kallikrein-related peptidase-3 (KLK3), androgen receptor splice-variant 7 (ARV7), f...