A trial of alpelisib and fulvestrant for breast cancer that has come back or continued to grow after hormone therapy (SOLAR-1)

Cancer type:

Breast cancer

Status:

Results

Phase:

Phase 3

This trial compared alpelisib and fulvestrant with fulvestrant alone, for people with breast cancer that had grown into surrounding tissue or had spread.  It was for men and for postmenopausal women whose cancer:

  • had oestrogen receptors, progesterone receptors, or both
  • didn’t have the protein HER2

The trial was open for people to join between 2015 and 2017, and the team first published results in 2019.

More about this trial

Doctors often treat breast cancer that has oestrogen or progesterone receptors (is hormone receptor positive) with hormone therapy. But sometimes the treatment stops working and the cancer starts to grow again.

The researchers wanted to find out if a targeted treatment called alpelisib would be useful for people in this situation. It is a type of cancer growth blocker

Alpelisib blocks the actions of proteins called PI3Ks. These proteins send signals telling cells to divide and grow. A gene called PIK3CA controls the amount of P13K protein in the cells.  

Some people have a change (mutation) in the PIK3CA gene. So P13K proteins are less well controlled. This means the cells can divide and grow in an uncontrolled way.

Researchers hoped that alpelisib would help block P13K proteins in people with a PIK3CA gene mutation.

They hoped that having alpelisib with a hormone therapy called fulvestrant would help control the cancer for longer. 

The main aims of this trial were to find out:

  • how well alpelisib and fulvestrant works compared to fulvestrant alone
  • more about the side effects

Summary of results

The research team found that fulvestrant and alpelisib helped stop breast cancer growing. They also found it caused more side effects than fulvestrant alone.

Trial design
This trial was for men and for women who had been through the menopause Open a glossary item. They had already had hormone therapy, but their breast cancer had spread. They all had cancer which had oestrogen or progesterone hormone receptors (or both) but didn’t have the protein HER2.

The people taking part were put into 1 of 2 treatment groups at random. They either had:

The trial was done to see how well treatment worked for people who had a change (mutation) in a gene called the PIK3CA gene. But people who didn’t have a change in this gene could also take part in a separate group.

Results
In total 572 people took part in this trial, including 1 man and 571 women:

  • 341 had a change in the PIK3CA gene
  • 231 didn’t have a change in the PIK3CA gene

People in each of these groups were then put into a treatment group at random:

  • 169 people with a gene change had fulvestrant and alpelisib
  • 172 people with a gene change had fulvestrant and placebo
  • 115 people without a gene change had fulvestrant and alpelisib
  • 116 people without a gene change had fulvestrant and placebo
     

The research team looked at how long it was until people’s cancer started to grow. 

For people who had a gene change, it was:

  • 11 months for those who had fulvestrant and alpelisib
  • 5.7 months for those who had fulvestrant and placebo

 


And for people who didn’t have a gene change, it was:

  • 7.4 months for those who had fulvestrant and alpelisib
  • 5.6 months for those who had fulvestrant and placebo

In 2020, the research team looked at how long people in both groups lived. This is called overall survival. They found it was:

  • 3 years and 3 months for those who had fulvestrant and alpelisib
  • 2 years and 7 months for those who had fulvestrant and placebo

The results of the two groups look quite different. But the difference isn’t big enough for the research team to say for sure that it’s because of the different treatments. It could be due to chance.

Side effects
Most people who took part had at least 1 side effect. But many were mild or got better. Some people did have more serious side effects:

  • more than 3 out of 10 people (35%) who had fulvestrant and alpelisib
  • less than 2 out of 10 people (17%) who had the fulvestrant and placebo

The most common of the more serious side effects for people who had alpelisib were:

  • an increase in blood sugar level (hyperglycaemia)
  • rash
  • diarrhoea

We have more information about the side effects of fulvestrant in our Cancer drugs section.

Conclusion
The research team concluded that fulvestrant and alpelisib helped stop breast cancer growing for longer than fulvestrant alone. This was for people whose cancer had already spread after hormone therapy, and who had a change in the PIK3CA gene. They also found it caused more side effects.

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.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Professor Samreen Ahmed

Supported by

Novartis

Freephone 0808 800 4040

Last review date

CRUK internal database number:

14061

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Caroline took part in a clinical trial for breast cancer

“I had treatment last year and I want to give something back.”

Last reviewed:

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