Abiraterone acetate, an androgen biosynthesis inhibitor, improves overall survival in patients with metastatic castration-resistant prostate cancer after chemotherapy.
Researchers have evaluated this drug in patients who had not received previous chemotherapy.
In a double-blind study, investigators have randomly assigned 1088 patients to receive Abiraterone acetate ( 1000 mg ) plus Prednisone ( 5 mg twice daily ) or placebo plus Prednisone.
The coprimary end points were radiographic progression-free survival and overall survival.
The study was unblinded after a planned interim analysis that was performed after 43% of the expected deaths had occurred.
The median radiographic progression-free survival was 16.5 months with Abiraterone - Prednisone and 8.3 months with Prednisone alone ( hazard ratio for Abiraterone - Prednisone versus Prednisone alone, HR=0.53; P less than 0.001 ).
Over a median follow-up period of 22.2 months, overall survival was improved with Abiraterone - Prednisone ( median not reached, vs 27.2 months for Prednisone alone; HR=0.75; P=0.01 ) but did not cross the efficacy boundary.
Abiraterone - Prednisone showed superiority over Prednisone alone with respect to time to initiation of cytotoxic chemotherapy, opiate use for cancer-related pain, prostate-specific antigen progression, and decline in performance status.
Grade 3 or 4 mineralocorticoid-related adverse events and abnormalities on liver-function testing were more common with Abiraterone - Prednisone.
In conclusion, Abiraterone has improved radiographic progression-free survival, has showed a trend toward improved overall survival, and significantly has delayed clinical decline and initiation of chemotherapy in patients with metastatic castration-resistant prostate cancer. ( Xagena )
Ryan CJ et al, N Engl J Med 2013; 368:138-148