Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy

STAMPEDE (also known as MRC PR08) is a multi-arm multi-stage (MAMS) randomised controlled trial recruiting in the UK and Switzerland. It aims to evaluate multiple therapeutic strategies in the management of high-risk locally advanced and metastatic hormone-naïve prostate cancer. Each novel treatment strategy is compared against a single, contemporaneous control arm. When the trial originally opened in 2005 there were 6 research arms enabling 5 randomised comparisons. Each comparison is evaluated in stages with pre-planned interim analyses after which recruitment may be halted should the experimental treatment fail to reach a "hurdle" of activity. Patient data from all arms and all stages are, however, included in the final analyses of the primary outcome measure, even if the investigational arm did not proceed to the final stage. Providing sufficient activity is demonstrated, recruitment continues to the final stage and then an assessment of efficacy is determined based on the primary outcome of overall survival. Patient data from all arms and all stages are included in the final analyses of the primary outcome measure, even if the investigational arm did not proceed to the final stage. The original comparisons which have all now been reported, evaluated a bisphosphonate (zoledronic acid), a cytotoxic chemotherapeutic agent (docetaxel) and a cyclooxygenase (Cox 2) inhibitor (celecoxib), as single agents or combinations. Since the start of the trial, a number of new research arms have been added to STAMPEDE over time to evaluate: abiraterone, a steroid synthesis inhibitor; prostate radiotherapy for patients with newly diagnosed metastatic disease; enzalutamide, an inhibitor of androgen receptor signalling, given with abiraterone; and metformin, an anti-diabetic medication and transdermal oestradiol, to be given as an alternative form of ADT. Objectives: Primary To compare the safety and efficacy of novel therapeutic strategies against the current standard-of-care for men with high-risk locally advanced or metastatic prostate cancer starting long-term ADT for the first time. Outline: This is a randomised, controlled, multi-centre MAMS trial platform. Patients are current randomised to 1 of 3 arms: control group (arm A), metformin treatment group (arm K) and transdermal oestradiol (Arm L). The other arms are all closed to recruitment with results known for all the original comparisons and awaited for others added since the trial commenced. Patient population: STAMPEDE recruits both men with high-risk locally advanced prostate cancer and men with metastatic prostate cancer, all of whom must be starting long-term ADT for the first time. Patients who received previous radical treatment and are now relapsing with high-risk features are also eligible. Follow-up: All patients are follow-up life long Sub-studies: There are several translational sub-studies ongoing as part of STAMPEDE. Participation is optional. These currently include several translational sub-studies involving sample collection: saliva collection for germline DNA analysis, sequential circulating tumour DNA analysis and FFPE tumour block retrieval for DNA and RNA analysis. Other sub-studies include a QOL sub-study and an imaging sub-study.