Treatment with abiraterone acetate, an androgen biosynthesis inhibitor, may benefit patients with progressive metastatic castration-resistant prostate cancer who have not yet undergone chemotherapy, report researchers.
Adding abiraterone to low-dose prednisone significantly prolonged radiographic progression-free survival among such patients compared with the addition of placebo.
The time patients had until they needed to be treated with opiate-based painkillers or chemotherapy was also extended in the abiraterone-prednisone versus prednisone only group.
"Despite the various therapies available for men with metastatic castration-resistant prostate cancer, a need remains for effective nontoxic agents that can improve and maintain the quality and duration of life while preventing the morbidity associated with disease progression," say Charles Ryan (UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, USA) and colleagues.
Although an overall improvement in survival has been seen among patients who take abiraterone acetate after they have undergone chemotherapy, this study is the first to evaluate its efficacy in patients who have not yet received chemotherapy.
As reported in The New England Journal of Medicine, the randomized trial including 1088 patients showed that among those who received abiraterone acetate 1000 mg plus prednisone 5 mg twice-daily, the median radiographic progression-free survival was 16.5 months compared with 8.3 months among those who received placebo plus prednisone.
Over a median follow-up period of 22.2 months, a greater proportion of deaths occurred among individuals on prednisone alone than among those who had abiraterone added, at 186 (35%) of 542 individuals versus 147 (27%) of 546, respectively. There was also a significant 25% decrease in the risk for death in the abiraterone-prednisone group compared with the prednisone alone group.
Furthermore, abiraterone plus prednisone showed superiority over prednisone alone in terms of time to initiation of chemotherapy, time to the use of opiate analgesics for cancer-related pain, time to prostate-specific antigen progression, and decline in performance status (as assessed by the Eastern Cooperative Oncology Group performance scale).
Liver function abnormalities and cardiac toxic effects were more common in the abiraterone-prednisone patients than in the prednisone only group. However, there was no significant between-group difference in the proportion of individuals discontinuing therapy due to adverse events, at 19% in the abiraterone-prednisone group and 12% in the prednisone alone group.
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