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

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Please note - this trial is no longer recruiting patients. We hope to add results when they are available.

Cancer type:

Breast cancer




Phase 3

This study is for people with breast cancer that has grown into surrounding tissue (is locally advanced) or has spread elsewhere in the body. 

It is open to men and postmenopausal Open a glossary item women whose breast cancer cells have:

  • receptors for oestrogen or progesterone (is hormone receptor positive)
  • low or no amounts of HER2 (this is called HER2 Open a glossary item negative breast cancer)

More about this trial

Hormone therapy is one of the usual treatments for breast cancer that is hormone receptor positive. You might have a type of hormone therapy called an aromatase inhibitor such as anastrazole, letrozole or exemestane. But sometimes this can stop working and the cancer can come back or get worse. Researchers are looking for ways to improve treatment for this group of people. In this study, they are looking at a new drug called alpelisib.

Alpelisib is a cancer growth blocker. It works by blocking the actions of proteins called PI3K (a PI3K inhibitor). This can stop signals that cancer cells use to divide and grow.

Researchers think that having alpelisib with a usual hormone therapy called fulvestrant will help control the cancer for longer. But they want to find out more.

The aims of this study are to:

  • find out how well alpelisib and fulvestrant works compared to fulvestrant alone
  • find out what happens to alpelisib and fulvestrant in the body
  • learn more about the side effects

Who can enter

The following bullet points list the entry conditions for this study. Talk to your doctor or the study team if you are unsure about any of these. They will be able to advise you. 

You might be able to join this study if you have breast cancer and one of the following applies.

You have had:

  • hormone therapy before or after surgery and your cancer has come back but you haven’t had treatment for cancer spread to another part of the body 
  • hormone therapy after surgery, your cancer came back after a year and then got worse after treatment with 1 type of hormone therapy for secondary breast cancer Open a glossary item
  • treatment with 1 type of hormone therapy for newly diagnosed secondary breast cancer and your cancer has come back

As well as one of the above, you might be able to join this study if all of the following apply. 

  • Your cancer has grown into the surrounding tissues and can’t be removed with an operation, or has spread to another part of the body
  • Your cancer is hormone receptor positive  - there are a large number of oestrogen or progesterone hormone receptors 
  • Your cancer has few, or no receptors for HER2 (it is HER2 negative)
  • Your cancer has come back during or after having a type of hormone therapy drug called an aromatase inhibitor such as letrozole, anastrazole or exemestane
  • There is a tissue sample of your cancer available for the study team to do some tests to find out if you have changes to the PIK3CA gene or not 
  • You have 1 area of cancer that can be seen on a scan or the cancer has caused holes in the bone (lytic bone lesions) and you have at least 1 lesion 
  • Women taking part have been though the menopause
  • You have satisfactory blood test results
  • You are well enough to carry out all your normal activities, apart from heavy physical work (performance status 0 or 1)
  • Men taking part are willing to use reliable contraception for up to 8 months if there is any chance their partner could become pregnant
  • You are at least 18 years old

You cannot join this study if any of these apply. You

  • Have a type of breast cancer called inflammatory breast cancer 
  • Have cancer that has spread to the brain or spinal cord unless you have had treatment that finished at least 28 days ago, it is stable and you aren’t taking steroids or drugs to control seizures
  • Have cancer that has spread to organs, for example to the liver and is causing symptoms and your doctor doesn’t think you are suitable to have hormone therapy
  • Have had fulvestrant, alpelisib or drugs that target proteins called PI3K, mTOR or AKT
  • Have had chemotherapy unless it was before or after surgery
  • Have had radiotherapy in the last 4 weeks (in the last 2 weeks if it was radiotherapy for symptoms given only to a small area of your body)
  • Are having any other cancer treatment
  • Have had an experimental treatment as part of a clinical trial in the last month
  • Haven’t recovered from side effects of previous anti cancer treatments (apart from hair loss) unless they are mild
  • Have had surgery in the last 2 weeks and haven’t recovered from the side effects
  • Have had any other cancer in the last 3 years apart from early cancer of the cervix or non melanoma skin cancer that was successfully treated
  • Have problems with your heart, such as a heart attack in the last year, high blood pressure that is not well controlled, angina that is not well controlled, an abnormal rhythm of your heart, congestive heart failure that is causing symptoms, a very slow heart rate or the left side of the heart isn’t working well,
  • Have long term liver damage and your liver isn’t working well
  • Have diabetes that isn’t well controlled with medication
  • Are taking a drug that can’t be stopped within 14 days of starting treatment in this study and is herbal or is known to increase the risk of an abnormal heart rhythm or of developing a condition called torsade de pointes
  • Have a problem with your digestive system that might affect how you absorb the drug
  • Have a inflammation of the lung tissue (called pneumonitis)
  • Have had steroids in the last 7 days apart from inhalers, cream or steroids to replace hormones in the body
  • Are known to have HIV
  • Have active hepatitis B or hepatitis C
  • Have any other serious medical condition or mental health problem that the study team think could you taking part

Trial design

This is an international phase 3 study. The study team need about 560 people to take part including 8 from the UK.

The study is randomised. You are put into 1 of 2 treatment groups by computer. Neither you nor your doctor will be able to decide which group you are in. And neither of you will you know which group you are in either. This is called a double blind study.

  • one group have fulvestrant and alpelisib
  • the other group have fulvestrant and a dummy drug (placebo Open a glossary item)

Diagram showing SOLAR-1 trial design

You have fulvestrant as 2 injections, one into each buttock. You have the injections:

  • twice a month in the first month
  • then once a month 

Alpelisib and the dummy drug are tablets. You take the tablets once every day. 

You have treatment for as long as it is helping you and the side effects aren’t too bad. 

Tissue samples
The researchers need to check to see if your cancer has the PIK3CA gene change (mutation) or not. If they do not have this information you might need to give a tissue sample (biopsy Open a glossary item) of your cancer before you start treatment. About 220 people with non mutated cancer gene will take part and 340 people with the mutated cancer gene. If it isn’t possible to identify if you have a mutated breast cancer gene or not, you won’t be able to take part in the study. 

Researchers will also ask your permission to look for biomarkers Open a glossary item in your tissue sample. You can tell the researchers if you don’t want them to use your sample for this research. You can still take part in the study. 

Blood samples
You have some extra blood tests as part of this study. The researchers want to find out what happens to alpelisib in the body. 

They will also ask your permission to look for substances in your blood called biomarkers. The researchers are looking to see why treatments work better for some people than others. You don’t have to agree to have this blood test for research if you don’t want to. You can still take part in the study.

Quality of life
Everybody taking part will be asked to fill out 3 questionnaire before starting treatment, at set times during the study and after finishing treatment. The questionnaire will ask about any side effects you have had and about how you have been feeling. This is called a quality of life study.

Hospital visits

You’ll see the doctors and have some tests before you start treatment. The tests include:

  • CT or MRI scan
  • a physical examination
  • blood tests and urine tests
  • heart trace (ECG Open a glossary item)
  • heart scan (echocardiogram Open a glossary item) or MUGA scan Open a glossary item
  • bone scan

You go to hospital to have fulvestrant. You probably won’t need to stay overnight.

You see the doctor 2 to 3 times in the first 2 months and then once a month.
During each visit you have a physical examination, blood tests, and a heart trace. 

You have a CT scan and a MRI scan every: 

  • 8 weeks for 18 months
  • 12 weeks after that

This continues as long as your cancer stays the same and does not get worse. If your cancer gets worse, you stop treatment. Your doctor will talk to you about other treatment options. 

When you stop treatment you see the study team:

  • within 2 weeks
  • after 1 month for a check up

After that you see them every 3 months at a routine hospital appointment or they might phone you to see how you are getting on 

If you stopped treatment early due to side effects, you see the study team and have a scan every: 

  • 8 weeks for 18 months
  • 12 weeks 

until your cancer gets worse.

Side effects

As alpelisib is a new drug, there may be some side effects we don’t know about yet. The study team will monitor you during the time you have treatment and you will be given a phone number to call them if you are worried about anything.

The most common side effects of alpelisib are:

We have information about fulvestrant.

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


Freephone 0808 800 4040

Last review date

CRUK internal database number:


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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