The trial team found that buparlisib and fulvestrant worked better than fulvestrant on its own. But the side effects of buparlisib were quite severe so many women stopped treatment early.
Results
The researchers published the results in July 2017.
This was a phase 3 trial. 1,147 women took part. Their average age was 62. The women were put into 1 of the following groups at random, and:
- 576 had buparlisib and fulvestrant
- 571 had a dummy drug (placebo
) and fulvestrant
Neither they nor their doctor could choose which group they were in. Nor did they know which group they were in. We call this a double blind trial.
Everyone had treatment for as long as it was working and the side effects weren’t too bad.
The researchers looked at how long before the cancer started to grow again. This is called progression free survival. On average, this was:
- 6.9 months in women who had buparlisib and fulvestrant
- 5 months in women who had the dummy drug and fulvestrant
The researchers checked tissue samples from previous biopsies the women had. They also looked at blood samples for tumour cells that had broken away from the breast cancer and were circulating in the blood (circulating tumour cells).
They wanted to see who had changes to the PI3K gene in their breast cancer cells. They found:
- 372 women had a change to PI3K gene (had a mutation)
- 479 women didn’t have a change to the PI3K gene (didn’t have a mutation)
- in 296 women it wasn’t possible to tell
The researchers knew the PI3K status of 851 women. They looked at how long before the cancer started to grow again. This was on average:
- 6.8 months in women who had buparlisib and fulvestrant
- 4.5 months in women who had the dummy drug and fulvestrant
372 women had a PI3K gene change in their breast cancer cells. The average length of time before their cancer started to grow again was:
- 6.8 months in women who had buparlisib and fulvestrant
- 4 months in women who had the dummy drug and fulvestrant
Although the numbers look different for the above 2 groups, the difference wasn’t significant when tested mathematically.
Side effects
The most common serious side effects of buparlisib included:
- changes to blood tests that show how the liver is working
- high blood sugar levels
- skin rash
- mood disorders such as depression
People who had buparlisib also had more problems with:
- loss of appetite
- feeling or being sick
- diarrhoea
- sore mouth
Many women stopped treatment early. In most cases this was because of side effects. So, some didn’t have treatment, mainly buparlisib, for very long.
The results for how long women lived for overall aren’t available yet. This is because researchers are still following up some women who took part. The researchers hope to have this information towards the end of 2019.
Conclusion
The researchers concluded that fulvestrant and buparlisib improved the length of time before the cancer started to grow again compared with fulvestrant alone. But the side effects of buparlisib were quite bad. So, they don’t plan to do more trials using this combination of treatment.
The trial team say that other drugs like buparlisib (other PI3K inhibitors), that are more selective could work better. But they need to do more trials.
This trial has increased knowledge about what works and what doesn’t for advanced breast cancer.
We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed ) 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.
