The safety and efficacy of abiraterone in chemotherapy-naïve patients (n=1,088) was established in a randomised, placebo-controlled phase III study (COU-AA-302) using the co-primary endpoints of radiographic progression-free survival (PFS) and overall survival. Patients were either using an LHRH analogue or had previously undergone orchidectomy.
Progression-free survival doubled
The study was unblinded when 43% of the expected deaths had occurred following a preplanned interim analysis. The median radiographic PFS was doubled in patients receiving abiraterone compared with placebo: 16.5 months vs 8.3 months (HR 0.53, 95% CI 0.45–0.62, p<0.001). Abiraterone also improved overall survival but did not cross the efficacy boundary.
Serious mineralocorticoid-related adverse events and liver-function abnormalities were more common in the abiraterone arm.
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