Adding abiraterone to hormone therapy at the start of treatment for prostate cancer improves survival by 37 per cent, according to the results of one of the largest ever clinical trials for prostate cancer presented at the 2017 ASCO Annual Meeting in Chicago and published in the New England Journal of Medicine.
The results from the Cancer Research UK-funded STAMPEDE1 trial could change the standard of care for men with prostate cancer, making abiraterone a first-line treatment alongside hormone therapy.
This part of the STAMPEDE trial recruited around 1,900 patients.2 Half the men were treated with hormone therapy while the other half received hormone therapy and abiraterone. In men who were given abiraterone there was a 70 per cent reduction in disease progression.3
The drug is usually given to men with advanced prostate cancer that has spread and has stopped responding to standard hormone therapy, but this study shows the added benefit to patients who are about to start long-term hormone therapy.
Professor Nicholas James, chief investigator of the Cancer Research UK-funded STAMPEDE trial from the University of Birmingham, said: "These are the most powerful results I've seen from a prostate cancer trial - it's a once in a career feeling. This is one of the biggest reductions in death I've seen in any clinical trial for adult cancers.
"Abiraterone is already used to treat some men whose disease has spread but our results show many more could benefit. In addition to the improvements in survival and time without relapse, the drug reduced the rates of severe bone complications, a major problem in prostate cancer, by more than a half. I really hope these results can change clinical practice."
Alfred Samuels, 59, was diagnosed with advanced prostate cancer in January 2012 and joined the STAMPEDE trial two months later. He lives in Harrow with his partner and five children.
Alfred said: "It felt like my world fell apart overnight. The doctors explained that surgery wasn't an option for me because the cancer had spread beyond my prostate.
"But my clinician suggested that the STAMPEDE trial might be a good option. As part of the trial, I started taking abiraterone four times a day and had a hormone injection every eight weeks.
"During the first six months, tests showed that the treatment was working. I'm still on the trial, which I find reassuring and, fortunately, my cancer is being managed well."
Prostate cancer cells usually depend on testosterone to grow. Standard hormone therapy blocks the action of male sex hormones, halting the disease. Abiraterone goes further and shuts down the production of the hormones that fuel prostate cancer's growth.
Each year around 46,500 men are diagnosed with prostate cancer in the UK, and around 11,000 men die from the disease.
Sir Harpal Kumar, Cancer Research UK's chief executive, said: "These results could transform the treatment of prostate cancer. Abiraterone can clearly help many more prostate cancer patients than was first thought.
"The STAMPEDE trial is changing the face of prostate cancer because the flexibility of the trial design means that we can investigate a number of different treatment options rapidly and in parallel, enabling scientists to get results much more quickly than they usually would.
"Cancer Research UK scientists first discovered abiraterone and subsequently played a key role in its development, including funding the first clinical trials. This study adds to the importance of the drug."
The STAMPEDE trial is coordinated by the MRC Clinical Trials Unit at UCL and funded by Cancer Research UK. Previous results from the trial have already changed clinical practice - data released last year has led to docetaxel chemotherapy now being part of the standard of care for many men with prostate cancer. More data will come out in subsequent years, because of the innovative design of the trial.
Professor James added: "We are so incredibly thankful to the patients and clinical staff who have agreed to take part in this study. With their generosity, scientists can carry out research that will help save lives."
ASCO Abstract LBA5003: Adding abiraterone for men with high-risk prostate cancer (PCa) starting long-term androgen deprivation therapy (ADT): Survival results from STAMPEDE (NCT00268476).
Article: Abiraterone for Prostate Cancer Not Previously Treated with Hormone Therapy, Nicholas D. James, Ph.D., et al., New England Journal of Medicine, doi: 10.1056/NEJMoa1702900, published 3 June 2017.