A trial of active surveillance and apalutamide for prostate cancer (TAPS01)

Cancer type:

Prostate cancer

Status:

Results

Phase:

Pilot

This trial looked at a short course of apalutamide for early stage prostate cancer. It was for men whose cancer was contained within the prostate gland but there was a risk it may grow. They were being monitored (active surveillance).

The trial was open for people to join between 2018 and 2019. The researchers published the results in 2022.

More about this trial

Prostate cancer sometimes grows very slowly and doesn’t get big enough to cause any symptoms. So some men don’t need treatment straight away. They have regular checks, including blood tests and scans of the prostate instead. This is called active surveillance. If there are signs that the cancer is growing, they may then have treatment.

When this trial was done, there was no treatment option available to try and slow down or stop the cancer growing during active surveillance.

In this trial, the researchers looked at giving short term treatment to men during active surveillance. They used a drug called apalutamide.

Apalutamide is an anti androgen treatment. It blocks the effect of testosterone on prostate cells, so is sometimes called an anti hormone therapy. You may also hear it called hormone therapy.

Researchers wanted to find out if apalutamide could slow down the growth of prostate cancer in men having active surveillance. And whether this could reduce the need for major (radical) treatment to cure their cancer in the future. Radical treatment can have serious long term side effects.

First the trial team wanted to run a small feasibility trial, to see if it was worth running a larger trial.

The main aims of this trial were to find out:

whether a 3 month course of apalutamide could reduce the size of the cancer within the prostate
how long this effect lasted
whether it was worth running a larger trial

Summary of results

The trial team found that a 3 month course of apalutamide did reduce the size of the cancer. And, more importantly, that this effect lasted for at least 18 months after finishing treatment. They suggest a larger trial is done.

Trial design
This trial was for men who had early stage prostate cancer and had decided not to have treatment straight away. They were having regular checks to see if their cancer had changed. This would help the doctors decide whether they needed treatment or not. It is called active surveillance.

The research team asked men if they’d like to join the trial, and about 4 out of 10 men (40%) said they would. Of the 11 men who agreed to join, 9 completed the treatment as part of the trial.

They all took apalutamide tablets once a day for 3 months. They had an MRI scan before and after treatment to see if there had been any change in the size of their prostate cancer.

They also completed questionnaires. This was to see how the treatment had affected their quality of life.

Results
The research team used MRI scans to measure the size (volume) of the prostate cancer. They measured it in centimetres cubed (cm³).

They compared the size:

before treatment
at the end of treatment
12 months after treatment
18 months after treatment

The results showed that the cancer had got smaller in everyone who took part. The scans after treatment showed that, on average, the cancer was less than half the size it was before treatment. This is a reduction of more than 50%.

They also looked at the scans 12 and 18 months after treatment. They found that 18 months after treatment, the average size of the cancer was still 20% smaller than it was before treatment.

Side effects and quality of life
The people taking part answered questions before and after treatment about:

their general health and quality of life
any prostate cancer symptoms they were having
any side effects of treatment

The results showed that their general quality of life went down slightly while having treatment. But this started to improve within 6 weeks of finishing treatment.

The results before and after treatment were similar for many of the specific symptoms. But tiredness, constipation and diarrhoea got a bit worse for some people while they were having treatment. But they all improved once people stopped treatment.

Some people had an improvement in urinary symptoms. These symptoms include needing to wee more often or more urgently.

Everyone taking part had at least one side effect of treatment. But nearly all were mild or didn’t last long. Some people had side effects such as a rash that were more severe. But it started to get better within 6 weeks of finishing treatment.

As with other anti androgen treatments used to treat prostate cancer, some people had erection problems (erectile dysfunction). This also started to improve about 6 weeks after treatment

Conclusion
The trial team concluded that apalutamide reduced the size of the cancer for at least 18 months. And that the side effects didn’t last too long. They hope this will mean that fewer men on active surveillance will need radical treatment for their cancer.

The team are now planning to look at this in a larger phase 3 trial called TAPS02. They will compare apalutamide to not having any treatment, to see how well it works. They will look at what treatment people need, and when. This will be for men with early stage prostate cancer, but with a risk that the cancer will grow.

More detailed information
There is more information about this research in the reference below.

Please note, this article is not in plain English. It has been written for health care professionals and researchers.

A Feasibility Study of the Therapeutic Response and Durability of Short-term Androgen-targeted Therapy in Early Prostate Cancer Managed with Surveillance: The Therapeutics in Active Prostate Surveillance (TAPS01) Study
T Barrett and others
European Urology Open Science (2022). Volume 38, pages 17-24

Where this information comes from
We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item ) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.