Abstract 3158: Prostate cancer derived biomarkers within platelets have the ability to predict therapeutic response in castration resistant patients

Background: 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. In this article a novel platform for circulating biomarker analysis has been used to follow cancer-derived transcripts implicated in therapy resistance. Method: The platelet population of blood samples and QRT-PCR were used to identify selected biomarkers in CRPC patient's prior chemo- or androgen synthesis (AS)-directed therapies. The association between biomarker statuses (positive vs. negative) and therapy response, progression-free survival (PFS) and overall survival (OS) was examined. Results: 40 patients received either docetaxel (n = 17) or AS-directed (n = 23) therapy, with a therapy response rate of 29% respectively 48%. The cancer-associated biomarkers were present within the platelet fraction. Analyzing these biomarkers in the chemotherapy group were associated with a short OS (p = 0.025). In the AS-directed group, the biomarkers were associated with shorter PFS (p = 0.015), and with an increased risk of therapy failure (HR: 5,5; p = 0,023), as well as short OS (p = 0.012). Conclusions: Analyzing circulating biomarkers in the platelet population enables us to predict who will benefit from AS-directed therapy with high accuracy, and platelet based analysis of cancer derived biomarkers may be used in treatment stratification of patients scheduled for AS-directed therapies. Citation Format: Lee-Ann Tjon-Kon-Fat, Marie Lundholm, Thomas Wurdinger, Camilla Thellenberg-Karlsson, Anders Widmark, Pernilla Wikström, Jonas Nilsson. Prostate cancer derived biomarkers within platelets have the ability to predict therapeutic response in castration resistant patients. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3158.