Introduction: Several small studies have reviewed the efficacy of abiraterone acetate plus prednisolone (AAP) in clinical practice outside a trial setting. We report the largest cohort study of clinical outcomes in metastatic castrate-resistant prostate cancer (mCRPC) patients treated with AAP in a multicenter multiracial clinical setting.
Methods:A retrospective analysis on mCRPC patients treated at four tertiary hospitals in Singapore from 2012 to 2017 was conducted. Disease characteristics, treatment outcomes, and adverse events were retrieved from electronic medical records. Primary clinical end-point was overall survival (OS). A subset analysis of patients with various variables and OS curves were generated using the Kaplan-Meier method and compared using the log-rank test.
Results:Out of 200 patients with mCRPC treated with AAP, 163 (81.5%) patients were chemonaïve (CN) and 37 (18.5%) patients were postchemotherapy (PC), with the median age of 68 (34-87) and 65 (52-80) years, respectively. Median OS was 20.0 (95% CI, 18.3-22.9) and 10.5 months (95% CI, 1.1-40.5) for CN and PC cohorts, respectively. A subset analysis of 108 patients showed a significantly longer OS in patients who had prior ADT for more than 12 months in CN patients (P < 0.001). Incidences of G3/G4 events were around 6.6%; most common side effect being hypertension with an incidence of 2.4%.
Conclusions: Treatment of CN and PC patients with AAP was associated with a comparable OSand progression-free survival to the reported series. Patients who were responsive to prior ADT of 12 months or more were associated with an improved OS. K E Y W O R D S abiraterone acetate, efficacy, metastatic castrate resistant prostate cancer, overall survival 1 INTRODUCTION Androgen deprivation therapy (ADT) is the mainstay of treatment for metastatic prostate cancer. 1 Since 2012, novel anti-androgens like abiraterone acetate plus prednisone/prednisolone (AAP) or enzalutamide have been available in Singapore as a treatment option in the metastatic castrate-resistant prostate cancer (mCRPC) either prior to or after docetaxel. AA, is a prodrug of abiraterone, a specific inhibitor of CYP17 enzyme leading to persistent androgen biosynthesis inhibition. 1 Updated analysis of the COU-AA-302 and COU-AA-301 studies where AAP was randomized against placebo and prednisone in the chemotherapy naïve (CN) and postchemotherapy (PC) setting showed a significant improvement in median overall survival (mOS) of 34.7 versus 30.3 months (hazard ratio [HR] = 0.81; 95% Asia-Pac J Clin Oncol. 2020;16:75-79. c