In 2012, the drug abiraterone (Zytiga) was first made available on the NHS to treat men with advanced prostate cancer that has stopped responding to standard hormone treatment.
Now, a strong case is being made for the drug to be made available to even more men with prostate cancer.
According to results from the Cancer Research UK-funded STAMPEDE clinical trial, offering abiraterone plus prednisolone in combination with standard therapy to men with prostate cancer earlier, before the disease becomes resistant to standard hormone therapy, can help boost survival.
That’s the take home message from new findings presented at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago in the US.
The results of the trial, also published recently in the New England Journal of Medicine, show that giving this combination to men whose prostate cancer has spread, or has a high risk of doing so, extends their lives.
Experts have said the results could be practice-changing. So what would this mean for men with prostate cancer?
What did the trial look at?
The STAMPEDE trial is many different trials in one. It’s looking at new combinations of treatments for prostate cancer patients to see which, if any, can improve survival.
Results from some parts of the trial have already been reported. And other parts are still open and available for patients to join.
The part of the trial presented today focused on abiraterone, a drug our research played a leading role in discovering and developing. It works by blocking a molecule inside cells, which stops the body from producing the hormone testosterone. This is important for prostate cancer as testosterone can fuel the growth of tumour cells.
The STAMPEDE team wanted to see if combining abiraterone plus the steroid prednisolone with standard hormone therapy – which blocks or lowers the amount of testosterone in the body – reduced the chances of the disease coming back, or improved survival.
Combining the two could therefore be a double whammy – it would stop cancer cells using testosterone as a fuel to grow, and prevent the production of more testosterone.
It’s one of the biggest improvements in overall survival I’ve seen
– Professor Nick James
Approximately 1,900 men with prostate cancer who were at a high risk of their disease spreading, or who have prostate cancer that has already spread, took part in the trial and were followed for just over 3 years.
Just under half were treated with standard hormone therapy. The others were treated with standard hormone therapy plus abiraterone and prednisolone.
“We know androgen deprivation therapy works well for a lot of men with prostate cancer. But we wanted to see if we could improve things further,” says Professor Nick James, chief investigator of the STAMPEDE trial based at the University of Birmingham.
“That’s why we looked at combining abiraterone with hormone therapy – to see if this drug could give even more men with prostate cancer even more time with their family.”
When comparing the 2 groups, the researchers looked for 2 key results:
- Was there any difference between the groups in terms their disease coming back after treatment?
- Was there a difference between the 2 groups in terms of how many men survived after treatment?
What they found was something James describes as ‘the most powerful results’ he’s seen from a prostate cancer clinical trial.
Men who received the combination of abiraterone plus prednisolone and hormone therapy were far less likely to see their disease spread or get worse compared to those who received only hormone therapy.
But that doesn’t necessarily mean that these men were likely to live longer.
That’s why James and his team also looked at whether the combination improved survival. And it did.
They found that there were fewer deaths in the group who received the combined treatment (184 vs 262). And those men who received the combination were far more likely to be alive 3 years after treatment than those receiving hormone therapy only.
“It’s one of the biggest improvements in overall survival I’ve seen in any clinical trial for adult cancers,” says James. “To be part of something like this is a once in a career feeling.”
He’s also keen to point out that not only does this new combination improve survival and reduce the chances of a man’s cancer coming back, it also does so with fewer side effects.
I really hope these results can change clinical practice
– Professor Nick James
“As well as improving survival this drug combination also reduced severe bone complications, a major problem for prostate cancer patients, by more than 50%,” he says.
Excitingly, this trial shows that combining abiraterone and standard hormone therapy lowers the risk of death in men whose prostate cancer has already spread at the time of diagnosis.
The combined treatment also more than doubled the time before patients’ disease worsened, again signalling promise for offering abiraterone earlier in these men.
The potential impact
The purpose of clinical trials is to test new drugs and combinations of drugs to see if they’re better than existing treatments.
In the case of this part of the STAMPEDE trial, it’s certainly done the latter.
And for James, it’s something he hopes will change how men with prostate cancer are treated.
“For me, these results mean abiraterone combined with androgen deprivation therapy should be the new standard of care for men with early stage prostate cancer,” he says.
“I really hope these results can change clinical practice and that this drug can now be used to treat more men with prostate cancer, not just those with advanced disease.”
Fizazi, K. et al. (2017) Abiraterone plus Prednisone in Metastatic Castration-Sensitive Prostate Cancer. The New England Journal of Medicine. DOI: 10.1056/NEJMoa1704174
James, N.D. et al. (2017) Abiraterone for Prostate Cancer Not Previously Treated with Hormone Therapy. The New England Journal of Medicine. DOI: 10.1056/NEJMoa1702900