Source: ctu.mrc.ac.uk, home page of MRC Clinical Trials Unit at UCL
Aviation House, 125 Kingsway, London, WC2B 6NH, United Kingdom
Prostate cancer accounts for around one fifth of all cancers among men. In the UK there are around 25,000 new cases of prostate cancer each year, and around 10,000 deaths.
Most men are given hormone therapy if their prostate cancer has spread (metastasised), or if the cancer is very likely to spread. This usually stops the tumour from growing for a while. But in most cases over time the tumour will start to grow again.
The aim of this trial is to try to prevent the tumour re-growth by adding other treatment(s) to the hormone therapy. The trial is currently using enzalutamide and abiraterone in combination with hormone therapy or, for newly diagnosed metastatic patients only, radiotherapy in combination with hormone therapy. Celecoxib, zoledronic acid, docetaxel and abiraterone alone have previously been tested.
Adding chemotherapy to hormone therapy improves survival of men with prostate cancer, according to results from the STAMPEDE trial presented at the American Society of Clinical Oncology Annual Meeting on 31 May 2015.
The presentation reported results from 2,962 men who were assigned to four of STAMPEDE’s nine treatment arms:
* Standard treatment arm (at least three years of hormone therapy, with
or without radiotherapy)
* Standard treatment plus docetaxel (a chemotherapy drug) for six 3
* Standard treatment plus zoledronic acid (a drug used to treat bone
cancers) for two years
* Standard treatment plus both docetaxel and zoledronic acid.
These men were followed up for an average of 3.5 years. Six in 10 of these men had cancer that had distant spread beyond their prostate when joining the trial, and the rest had high-risk, locally advanced prostate cancer. The average age of men in the trial was 65.
Men in the group allocated the standard treatment plus docetaxel lived on average for 10 months longer than men who had the standard treatment alone. Docetaxel seemed to be particularly good for men whose disease had spread to other parts of their body, increasing average survival by 22 months.
Men in the group allocated the standard treatment plus zoledronic acid did not live longer than men who had the standard treatment alone.
Men in the group allocated the standard treatment plus docetaxel plus zoledronic acid as well as the standard treatment lived longer on average than those who had the standard treatment alone.
However, adding zoledronic acid to docetaxel did not seem to add any benefits beyond just docetaxel and the standard treatment.
While docetaxel was associated with some additional side effects compared to the standard treatment alone, as expected, the side effects were manageable.
STAMPEDE (Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy) is the largest randomized clinical trial of treatment for men with prostate cancer ever conducted, with nearly 7,000 patients enrolled since 2005. The trial, which continues to recruit new men, has an innovative multi-arm, multi-stage design.
The multi-arm multi-stage or “MAMS” design, which was developed by MRC CTU, allows several treatments to be assessed against a single control arm. Recruitment can be stopped early to treatments that are not sufficiently promising after interim analyses. New treatments that become available after the trial has started can also be added.
Matt Sydes said, “We have shown in STAMPEDE that we can put this innovative design into practice.”
These results will be published in full in a peer-reviewed journal later this year. Sites will continue to follow-up these men to look at longer-term outcomes. The STAMPEDE trial is also looking at a number of other approaches to treating men with prostate cancer.
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