Giving the drug abiraterone alongside standard hormone therapy improves the survival of men with high-risk or advanced prostate cancer, according to results from the STAMPEDE trial, published in the New England Journal of Medicine on 3 June 2017.
In the “abiraterone comparison” in STAMPEDE, 957 men who were randomised to receive standard of care (hormone therapy with or without radiotherapy) were compared to 960 men who were randomised to receive abiraterone plus prednisolone plus standard of care (hormone therapy with or without radiotherapy). Men in the abiraterone group had four abiraterone tablets and one prednisolone tablet a day.
Abiraterone (also known as abiraterone acetate, or Zytiga) is a type of hormone therapy that works in a different way to standard hormone therapy. Abiraterone is currently licensed to treat prostate cancer that has spread and has stopped responding to standard hormone therapy. STAMPEDE tested using it earlier, when men were starting standard hormone therapy.
The data were presented the same day at the American Society of Clinical Oncology (ASCO) conference in Chicago, USA.
All the men taking part in the abiraterone comparison of STAMPEDE:
- had high risk prostate cancer, or prostate cancer that has already spread to the nodes or other parts of the body;
- were starting long-term hormone therapy for the first time;
- were fit enough to have chemotherapy.
After an average of around 3.5 years of follow-up, 262 deaths had occurred in the standard therapy group and 184 in the abiraterone group. The proportion of men alive three years after joining the trial was 83% in the abiraterone group compared with 76% in the standard therapy group.
Abiraterone also lowered the relative chance of treatment failure (measured by worsening scans or symptoms or elevated PSA level) by 71% compared to standard therapy. The effects were consistent across the different subgroups of men joining the trial.
Overall, side effects were similar between the two groups. Severe side effects were more common in the abiraterone group, occurring in 47% of patients compared to 33% of patients in the standard therapy group. The main side effects occurring more frequently with abiraterone were cardiovascular problems such as hypertension; there were also more liver problems.
STAMPEDE abiraterone results: summary from MRC Clinical Trials Unit at UCL on Vimeo.
“Abiraterone not only prolonged life, but also lowered the relative chance of relapse and reduced the relative chance of serious bone complications” said STAMPEDE Chief Investigator Nicholas James, Professor of Clinical Oncology at Queen Elizabeth Hospital in Birmingham. “Based on the magnitude of benefit, we believe that the upfront care for patients newly diagnosed with advanced prostate cancer should change. However, before this can happen, there will need to be an extension to the licence for the drug and funding approval from the NHS and NICE. This is likely to take many months and perhaps even longer.”
STAMPEDE is the largest prostate cancer treatment trial ever, with more than 9,000 men taking part. The trial, which continues to recruit new men, has an innovative multi-stage, multi-arm design, which was developed and run by the MRC Clinical Trials Unit at UCL. The multi-arm multi-stage or “MAMS” design, which was developed by the MRC CTU at UCL, allows several treatments to be assessed against a single control arm, and for new treatments to be added to the trial as it progresses.
Mahesh Parmar, Director of the MRC Clinical Trials Unit at UCL, said, “This innovative design allows us to achieve answers to questions decades before the more traditional sequential 2-arm trial approach to testing new treatments.”
Matthew Sydes, senior statistician for STAMPEDE at MRC Clinical Trials Unit at UCL, said, “This is the second major result from STAMPEDE showing that a new treatment improves survival for men with prostate cancer. The trial shows how patients, doctors and researchers can work together to develop and implement new methods of doing trials which can more rapidly identify such treatments.”
The STAMPEDE trial is taking place at more than 100 hospitals across the UK and in Switzerland. It is run by the MRC Clinical Trials Unit at UCL. The STAMPEDE trial is funded by Cancer Research UK, the Medical Research Council, Astellas, Clovis Oncology, Janssen, Novartis, Pfizer and Sanofi-Aventis.