Advanced PCa agent approved for pre-chemo use

The FDA has approved a broader indication for the advanced prostate cancer treatment abiraterone acetate (ZYTIGA).

Until now, abiraterone with prednisone has only been approved to treat men with metastatic castration-resistant prostate cancer who have received prior chemotherapy containing docetaxel (Taxtoere). With this approval, abiraterone, in combination with prednisone, may now be used prior to chemotherapy.

Abiraterone also received a positive opinion for an expanded indication from the European Medicines Agency’s Committee for Medicinal Products for Human Use and is under review by other health authorities worldwide.

"This expanded indication for ZYTIGA helps fill a critical medical need, providing physicians an important tool for treating men with metastatic castration-resistant prostate cancer who have not received chemotherapy," said Charles J. Ryan, MD, of the University of California, San Francisco, lead investigator of the pivotal phase III study on which the new approval is based.

The phase III randomized, double-blind, placebo-controlled international clinical study, which was published online in the New England Journal of Medicine (Dec. 10, 2012), evaluated abiraterone plus prednisone compared to placebo plus prednisone in 1,088 men with metastatic castration-resistant prostate cancer who had failed androgen deprivation therapy and had not received cytotoxic chemotherapy.

Results from a pre-specified analysis examining radiographic progression-free survival (rPFS) demonstrated a statistically significant improvement in rPFS in the abiraterone plus prednisone arm compared to the placebo plus prednisone (control) arm. The median rPFS in the control arm was 8.28 months but had not yet been reached in the abiraterone arm because progression events were occurring more slowly in the abiraterone arm compared to the control arm (p<.0001).

Additionally, in a separate pre-specified interim analysis, overall survival was longer for the abiraterone arm compared to the control arm with a hazard ratio of 0.792: median overall survival was 35.3 months in the abiraterone arm versus 30.1 months in the control arm (95% CI: 0.655-0.956). The p-value was .0151, which did not meet the pre-specified value for statistical significance.

Dr. Ryan and several of his co-authors have received grants, payment for lectures including service on speaker’s bureaus; honoraria; support for travel to meetings for the study or other purposes; fees for participation in review activities such as data monitoring boards, statistical analysis, end point committees, etc.; and/or are employees of Janssen.