Recruitment to the "abiraterone comparison" of STAMPEDE was completed on 17 January 2014, after the recruitment target was reached. This is a major milestone for the trial because the "abiraterone comparison" was the first of the new comparisons to be incorporated into this ongoing multi-arm multi-stage trial. Most trials have only two arms and do not change. STAMPEDE started with six arms, and has efficiently drawn in further comparisons over time.
Rates of accrual to STAMPEDE were remarkable throughout 2013 with an average of around 150 patients per month. The recruitment target for the "abiraterone comparison" of 1800 men with hormone-naïve prostate cancer was reached in 26 months instead of the predicted 36 months.
The "abiraterone comparison" compares men randomised over the same period of time to either the control group (Arm A: standard care with androgen deprivation therapy with or without radiotherapy) or the abiraterone group (Arm G: standard care plus abiraterone and prednisone).
Recruitment to the abiraterone group started five years after the trial originally opened, but has been completed only 10 months after completion of recruitment to the original research arms. The original research arms assessed adding one or two of zoledronic acid, docetaxel or celecoxib to standard care.
The primary outcome measure for all comparisons is overall survival. Follow-up activity continues for all trial patients. The results of the different comparisons within STAMPEDE are eagerly awaited.
Recruitment to the trial continues to the "M1/RT comparison" which looks at radiotherapy-to-the-prostate in men whose disease has already spread elsewhere. This was the second new comparison, initiated in January 2013. A third new comparison, the "enzalutamide + abiraterone comparison", should start recruitment in March with the initiation of Arm J. More information will follow.
More than 5,000 patients from across the UK and Switzerland have joined STAMPEDE, demonstrating the feasibility and benefits of conducting new comparisons within an ongoing trial.
The STAMPEDE team would like to thank all of the site staff and patients involved in the trial.