HealthDay News — The FDA has expanded the indication for abiraterone acetate (Zytiga, Janssen Biotech) to include treating late-stage castration-resistant prostate cancer before the administration of chemotherapy.
The drug, designed to decrease production of testosterone, was first approved in November 2011 for use in patients whose prostate cancer progressed after treatment with docetaxel.
Abiraterone works by decreasing a protein involved in testosterone production, P450 17A1, that helps curb cancer cell growth.
The expanded indication comes after results from a phase III clinical trial involving 1,088 men with advanced, castration-resistant prostate cancer who hadn’t received chemotherapy, showed improved progression-free survival with abiraterone acetate vs. placebo. Results from the safety and efficacy trial were published in in the New England Journal of Medicine.
The median radiographic progression-free survival was 16.5 months with the abiraterone-prednisone combination and 8.3 months with prednisone-placebo (hazard ratio for abiraterone-prednisone vs. prednisone-placebo=0.53, 95% CI: 0.45-0.62, P<0.001), Charles Ryan, MD, of the University of California San Francisco, and colleagues reported.
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; hazard ratio, 0.75; 95% CI: 0.61-0.93; P=0.01), but did not cross the efficacy boundary.
“Abiraterone improved radiographic progression-free survival, showed a trend toward improved overall survival, and significantly delayed clinical decline and initiation of chemotherapy in patients with metastatic castration-resistant prostate cancer,” the researchers wrote.
The most common adverse reactions included fatigue, swollen joints, hot flushes, diarrhea, vomiting, cough, and high blood pressure.