Prostate cancer: Study identifies earlier clinical trial endpoint that can be used to indicate effectiveness of new treatments
Scientists say they have validated a “surrogate endpoint” – a reliable statistical shortcut in a clinical trial – that could accelerate testing of new adjuvant therapies aimed at reducing deaths from prostate cancer in patients who were treated for localized disease, but are at risk of relapse. Reporting in the Journal of Clinical Oncology, an international team of researchers, led by Christopher Sweeney, MBBS, of Dana-Farber Cancer Institute, found that measuring metastasis-free survival (MFS) – the length of time before the cancer spread beyond the prostate gland – was a strong predictor of patients’ overall survival (OS), which is the yardstick commonly used in evaluating an adjuvant therapy. The analysis found that OS requires a longer follow-up period to measure than does MFS, and that using MFS as an endpoint could enable more clinical trials to be carried out in a shorter period of time.
Sweeney is the corresponding author representing the Intermediate Clinical Endpoints of Cancer of the Prostate (ICECaP) Working Group, which carried out the study. The ICECaP Working Group comprises more than 50 investigators including statisticians, medical oncologists, urologists, radiation oncologists, and health economists from several dozen institutions around the globe.
Adjuvant therapies are drugs given following initial treatment of prostate cancer with radiation or surgery. They are aimed at ridding the body of cancer cells that survived initial treatment, and may save lives from prostate cancer.
Prostate cancer is a slow growing disease; therefore, it typically takes 10 to 12 years to evaluate an experimental adjuvant therapy for localized prostate cancer in clinical trials that use OS as the endpoint. With a number of new adjuvant drugs undergoing evaluation for this patient group, Sweeney said researchers in the field are seeking ways to get answers quicker and make effective drugs available sooner.
The patients in question are men whose cancer was confined to the prostate gland and were treated with radiation or surgery, but are considered to be at medium or high risk of relapse because of the aggressiveness of other pathological features of their tumor. Adjuvant drugs currently being evaluated include alpharadin, enzalutamide, abiterone, docetaxel, cabazitaxel, and sipuleucel-T vaccine.