Biomarkers of prolonged time to treatment failure in metastatic castration-resistant prostate cancer patients treated with abiraterone or enzalutamide: A real life patients-based nomogram and web app

202 Background: Survival outcomes for metastatic castration resistant prostate cancer (mCRPC) patients (pts) have greatly improved following the approval of Docetaxel and abiraterone(Abi)/enzalutamide(Ez). However, it is not clear who is likely to benefit more from these therapies in real life clinical practice. Methods: A retrospective cohort study was performed with mCRPC pts treated with Abi/Ez in pre-Docetaxel setting. Primary endpoint: to identify predictive biomarkers of long time to treatment failure (TTF), develop a nomogram and convert it into a web app. Secondary endpoint: to correlate biomarkers with overall survival (OS). Kaplan Meier survival estimates and Cox Regression models were used for time-to-event analyses. Statistical analysis was made with R software. All statistical tests were two-sided and statistical significance was fixed at 0.05. Results: From May2012 to October2017, 117 pts were assessed, 81 received Abi and 36 Ez. Median follow-up of 21 months (mo), estimated median TTF was 12.8mo (95%CI 9.98-15.7) for the total population. Predictive biomarkers for TTF included in the first nomogram model were time from start of androgen deprivation therapy (tADT) to start of Abi/Ez, pain at baseline, Gleason score, baseline testosterone and lower PSA nadir in castration sensitive prostate cancer (CSPC). The second nomogram model included pain and Gleason plus neutrophil counts, tADT to CRPC and baseline PSA at CRPC. C-index: 0.726 and 0.731 respectively, providing a reliable prediction of long-term benefit with Abi/Ez in this setting. All these characteristics were significantly associated with OS. Conclusions: The two nomogram achieved a good internal validation and can work as a tool to the decision-making process of the best strategy to first-line therapy in mCRPC pts.[Table: see text]