Abiraterone, combined with standard therapy, helps men with metastatic prostate cancer to live longer
17 May 2022
Adding the drug abiraterone to standard hormone therapy improves the survival of men with prostate cancer that has spread to other parts of the body. This result from the STAMPEDE trial was published, open access, in the International Journal of Cancer journal yesterday.
These findings from the “abiraterone comparison” are a long-term follow-up study from STAMPEDE. It assessed the effects of adding abiraterone to standard hormone therapy to treat metastatic prostate cancer. In these patients, their cancer has already spread beyond the prostate.
Abiraterone (also known as abiraterone acetate, or Zytiga) is a type of hormone therapy that works in a different way than the standard hormone therapy. Currently, abiraterone is only offered to men with “high-risk” metastatic prostate cancer (men with a larger number of metastases), or to men whose cancer has stopped responding to the standard hormone therapy.
To evaluate if adding abiraterone improves the survival of patients with metastatic prostate cancer, 1,003 patients with metastatic prostate cancer were randomly assigned between two groups to receive either:
- standard hormone therapy alone
- abiraterone (and prednisolone, a steroid to manage abiraterone side effects) plus standard hormone therapy
The study took place in the UK and Switzerland and included men with metastatic disease whose prostate cancer was newly-diagnosed or had returned after being treated previously with only radiotherapy or surgery. Consenting participants were followed-up for at least five years after they were assigned randomly to one of the two treatment groups.
The “abiraterone comparison” found that at five years after randomisation, the proportion of men alive was 60% in the abiraterone group, compared with 41% in the standard hormone therapy alone. Therefore, adding abiraterone improved the survival of men with metastatic disease by approximately one in five at five years.
When men were classified according to the extent of their metastatic disease (indicating their risk of worse outcomes as lower or higher), the effect of adding abiraterone was comparable in each group. These results suggest that all patients would potentially benefit from adding abiraterone to the standard hormonal therapy, irrespectively of their metastatic risk group. Currently, abiraterone only has a license in higher-risk metastatic prostate cancer.
Adding abiraterone also improved other outcomes, including failure-free survival, which indicates the proportion of men whose disease hasn’t got worse. At five years after randomisation, this was 45% in the abiraterone group, compared with 13% if they received standard hormone therapy alone.
Both groups reported similar side-effects.
Meta-analyses are studies that combine data from similar clinical trials. Looking at the findings of STAMPEDE with recent, long-term findings from Janssen’s LATITUDE trial, further confirmed the benefits of using abiraterone in all men with newly-diagnosed metastatic prostate cancer disease, irrespective of their risk group.
These results are clearly favourable for the addition of abiraterone and unlikely to change with any further follow-up.
The study was funded by Cancer Research UK (CRUK), the Medical Research Council (MRC), and the Swiss Group for Cancer Clinical Research (SAKK), with further support from industry collaborators including Janssen, Astellas, Prostate Cancer UK, Clovis Oncology, Novartis, Pfizer, and Sanofi-Aventis.
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