The secondary end points of the study included the median time to initiation of chemotherapy and initiation of opiate therapy for prostate cancer pain.  The study revealed a 39% decrease in the risk of cytotoxic chemotherapy initiation—a median of 26.5 months compared to 16.8 months for the control group.  Additionally, there was a 29% decrease in the risk of opiate use for cancer pain to a median time of 23.7 months for the control arm; the median time for the AA group not reached.

Grade 3/4 adverse events were more common in the AA group, but despite longer exposure to the agent, the safety profile remained favorable (Table 1).  Hypertension occurred in 4.2% of the AA group versus 3.1% of the placebo group; hypokalemia occurred in 2.6% versus 1.9%, respectively.  Liver enzymes were also higher in the AA group (ALT increased 5.5%; AST increased 3.1%) compared with the placebo group (ALT increased 0.7%; AST increased 0.9%).

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Table 1. Grade 3/4 Adverse Events Reported in COU-AA-3021

Grade 3/4 Adverse Events

Abiraterone acetate plus prednisone group


Placebo plus prednisone group


Hypertension 4.2% 3.1%
 Hypokalemia  2.6%  1.9%
Increase in ALT 5.5%  0.7%
Increase in AST 3.1% 0.9% 

“The COU-AA-302 study has confirmed that targeting the androgen signaling pathway remains a meaningful intervention for patients with metastatic castration-resistant prostate cancer.  Patients with metastatic castration-resistant prostate cancer without prior chemotherapy who are in need of treatment now have options beyond standard chemotherapy,” said Dr. Rathkopf regarding the study outcomes in an interview with

Dr. Crawford also indicated, “This study (COU-AA-302) is a very important study because it is a game-changer and suggests moving this agent up prior to chemotherapy.”

Results from the more recent analyses and earlier interim analyses from COU-AA-302 were the basis for the December 2012 U.S. Food and Drug Administration (FDA) approval of an expanded indication for AA in combination with prednisone for treating men with metastatic prostate cancer.