Clinical significance of AR amplification from CF DNA among Japanese castration-resistant prostate cancer patients.

314Background: We study the prognostic ability of androgen receptor amplification (AR amp) from cf DNA in Japanese castration-resistant prostate cancer (CRPC) patients. Methods: Multiple sets of serums were obtained from 38 castration-resistant prostate cancer patient at Chiba University hospital. Serum cfDNA was purified using a cobas cfDNA Sample Preparation Kit. AR copy number was measured using the QX100 Droplet Digital PCR System. Factors associated with progression-free survival (PFS) and Overall Survival (OS) were statistically studied. Results: The number of patients received Enzalutamide (Enza)/Abiraterone (Abi)/Docetaxel (Doc) were 33/25/11. Regarding PFS, the presence of AR amplification, Bone Scan Index (BSI), PSA was significant factors on univariate analysis. On multivariate analysis, AR amplification was an independent prognostic factor (HR. 8.9, p=0.003). Regarding OS, PSA and AR amp was significant factors. On multivariate analysis, AR amp (HR 4.2, p=0.028) was an independent prognostic f...