Adding abiraterone to standard prostate treatment improves survival by 40%, studies find

The hormone blocking drug abiraterone extended life in men with prostate cancer when used first line at the start of standard treatment, two studies have found.

Abiraterone is usually used in men whose prostate cancer has spread and has stopped responding to standard hormone therapy. But the two studies, published in the New England Journal of Medicine,12 suggest that it could benefit all men at the start of treatment, whether they have metastatic prostate cancer or prostate cancer that has not spread.

In the first study,1 part of the Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy (STAMPEDE) trial, investigators funded by Cancer Research UK randomly assigned 1900 men to hormone therapy (957 men) or to hormone therapy and abiraterone (960 men). Nearly all of the men (95%) had newly diagnosed prostate cancer, and around half had metastatic disease.

Over the median follow-up of 40 months 184 deaths were recorded in the combination treatment group (19%), compared with 262 in the hormone-only treatment group (27%), suggesting a 37% improvement in survival in the abiraterone group (hazard ratio 0.63 (95% confidence interval 0.52 to 0.76)).

Prostate cancer in the men treated with abiraterone was also 70% less likely to progress than in the men given standard treatment. The study found 248 (26%) treatment failure events (change in prostate specific antigen, spread to lymph nodes or other metastasis, or death from prostate cancer) in the men given abiraterone, compared with 535 (56%) in the standard treatment group (0.29 (0.25 to 0.34)).

Nicholas James, chief trial investigator, from the University of Birmingham, said, “These are the most powerful results I’ve seen from a prostate cancer trial—it’s a once-in-a-career feeling. This is one of the biggest reductions in death I’ve seen in any clinical trial for adult cancers.

“Abiraterone is already used to treat some men whose disease has spread, but our results show many more could benefit. In addition to the improvements in survival and time without relapse, the drug reduced the rates of severe bone complications, a major problem in prostate cancer, by more than a half. I really hope these results can change clinical practice.”

Harpal Kumar, Cancer Research UK’s chief executive, said that the results “could transform the treatment of prostate cancer.”

In the second study,2 1199 men with newly diagnosed metastatic prostate cancer were randomly assigned to receive hormone therapy or hormone therapy plus abiraterone. The study similarly found that, after 35 months, men treated with abiraterone were 42% less likely to have died (hazard ratio for death 0.62 (0.51 to 0.76)) and 53% less likely to have experienced disease progression or death than men treated with standard therapy (0.47 (0.39 to 0.55)).

The findings of this study, which was funded by Janssen, led to the trial being un-blinded to allow the men who had been getting standard treatment to receive abiraterone.

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