Real-world experience of abiraterone acetate plus prednisone in chemotherapy-naive patients with metastatic castration-resistant prostate cancer: long-term results of the prospective ABItude study.

background: limited real-world data exist on the effectiveness and safety of abiraterone acetate plus prednisone (abiraterone hereafter) in the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) naive to chemotherapy. most of the few available studies had a retrospective design and included a small number of patients. in the interim analysis of the abitude study, abiraterone showed good clinical effectiveness and safety profile in the chemotherapy-naive setting over a median follow-up of 18 months. patients and methods: we evaluated clinical and patient-reported outcomes (PROs) of chemotherapy-naive mCRPC patients treated with abiraterone as for clinical practice in the Italian, observational, prospective, multicentric abitude study. mCRPC patients were enrolled at abiraterone start (february 2016-June 2017) and followed up for 3 years; clinical endpoints and PROs, including quality of life (QoL) and pain, were prospectively collected. kaplan-meier curves were estimated. results: of the 481 patients enrolled, 454 were assessable for final study analyses. at abiraterone start, the median age was 77 years, with 58.6% elderly patients and 69% having at least one comorbidity (57.5% cardiovascular diseases). visceral metastases were present in 8.4% of patients. over a median follow-up of 24.8 months, median progression-free survival (any progression reported by the investigators), time to abiraterone discontinuation, and overall survival were, respectively, 17.3 months [95% confidence interval (CI) 14.1-19.4 months], 16.0 months (95% CI 13.1-18.2 months), and 37.3 months (95% CI 36.5 months-not estimable); 64.2% of patients achieved ≥50% reduction in prostate-specific antigen. QoL assessed by functional assessment of cancer therapy-prostate, the European quality of Life 5 dimensions 3 level, and european quality of life visual analog scale remained stable during treatment. median time to pain progression according to brief pain inventory data was 31.1 months (95% CI 24.8 months-not estimable). sixty-two patients (13.1%) had at least one adverse drug reaction (ADR) and 8 (1.7%) one serious ADR. conclusion: with longer follow-up, abiraterone therapy remains safe, well tolerated, and active in a large unselected population.