Abiraterone acetate: Interim Phase III data

Interim data from the double-blind, international Phase III COU-AA-301 trial in 1,195 patients with CRPC previously treated with 1 or 2 chemotherapy regimens, at least 1 of which contained Taxotere docetaxel, showed that 1,000 mg once-daily abiraterone plus 5 mg twice-daily predinose/prednisolone significantly improved OS by 36% vs. placebo plus prednisone/prednisolone (14.8 vs. 10.9 months). Abiraterone met the secondary endpoints of significantly improving time to PSA progression (10.2 vs. 6.6 months, p<0.0001) and rPFS vs. placebo (5.6 vs. 3.6 months, p<0.0001). Additionally, a significantly greater proportion of patients treated with abiraterone achieved a total PSA response vs. placebo (38% vs. 10%, p<0.0001). Abiraterone also significantly reduced the risk of death by 35% vs. placebo (p<0.0001).

The most frequent adverse events were fluid retention and hypokalemia. Liver function abnormalities (10.4% vs. 8.1%) and cardiac disorders (12.5% vs. 9.4%) occurred more frequently in the abiraterone arm vs. placebo arm. Data were presented at the European Society for Medical Oncology meeting in Milan. Last month, Johnson & Johnson unblinded the COU-AA-301 trial at the recommendation of an independent DMC after a pre-specified interim analysis showed that abiraterone met the primary endpoint of significantly improving OS vs. placebo, and had an acceptable safety profile (see BioCentury, Sept. 13). The partners have an SPA from FDA for the trial. ...