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A trial of ipilimumab for prostate cancer that has stopped responding to hormone therapy (CA184095)
This trial looked at a drug called ipilimumab for prostate cancer that was no longer responding to hormone therapy.
It was for men who only had mild symptoms, or no symptoms at all. And who hadn’t had chemotherapy.
More about this trial
If prostate cancer stops responding to hormone therapy, you might have chemotherapy. But if you don’t have any bad symptoms, your doctor might suggest you don’t start any other treatment. Instead, they can keep a close eye on you, and you have regular tests to monitor your cancer.
Researchers thought ipilimumab might help men in this situation, but they wanted to find out more about how well it worked, and how safe it was.
Ipilimumab is a type of targeted cancer drug (biological therapy) called a monoclonal antibody (MAB). Monoclonal antibodies target cancer cells by looking for particular proteins on the cells’ surface. Ipilimumab targets a protein called CTLA4. Ipilimumab stops CTLA4 from shutting down part of the immune system. So it may help the immune system to destroy cancer cells.
The aims of the trial were to:
- see if having ipilimumab helped men with prostate cancer live longer
- learn more about the side effects
Summary of results
The trial team found that treatment with ipilimumab didn’t help men with prostate cancer to live longer. But it did affect the length of time it took before some men’s cancer got worse. And the researchers found that the level of prostate specific antigen (
This was an international phase 3 trial. 602 people took part.
It was a randomised trial. Everyone was put into 1 of the following treatment groups by computer:
- a dummy drug (
Almost twice as many men were put into the ipilimumab group than the dummy drug group.
Neither they nor their doctor could choose which group they were in. And neither they nor their doctor knew which treatment they were having. This was a double blind trial.
The research team looked at the number of men that took part in each group:
- 399 men had ipilimumab
- 199 men had a dummy drug
4 men didn’t start their treatment after they were put into a group.
The study team looked at how well the treatment worked. To do this they looked at the average length of time people lived without any signs of their cancer getting worse. This is called progression free survival. They found it was:
- just under 6 months (5.6 months) for men in the ipilimumab group
- almost 4 months (3.8 months) for men in the dummy drug group
The researchers used men’s PSA level as a way of measuring if ipilimumab was working. If the PSA level went down by more than half from the starting level, the researchers thought the cancer was responding to ipilimumab.
The trial team found that the PSA level had gone down by more than half in around:
- 92 men in the ipilimumab group
- 16 men in the dummy drug group
They also looked at the amount of time people lived. This is called overall survival. They found it was:
- just under 29 months in the ipilimumab group
- almost 30 months in the dummy drug group
The trial team looked at the side effects men had. There were more side effects in the ipilimumab group than the dummy drug group. The most common side effects for the ipilimumab group were:
- a rash
- very itchy skin
Diarrhoea was the only severe side effect that more than 1 in 10 men (10%) in the ipilimumab group had.
The trial team concluded that ipilimumab does not help men with prostate cancer that has stopped responding to hormone treatment to live longer. But it did affect the length of time it took before some men’s cancer got worse. And it helped lower some men’s PSA level.
The researchers are not sure why ipilimumab:
- did not affect the length of time it took before all the men’s cancer got worse
- gave some men a longer time before their cancer got worse, but didn’t help them live longer
The team think more research should be done to see if it would be possible to predict who would benefit from ipilimumab before treatment starts. They also want to look at different targeted cancer drugs for men with prostate cancer that’s stopped responding to hormone treatment.
We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (
How to join a clinical trial
Dr Robert Jones
Experimental Cancer Medicine Centre (ECMC)