A trial looking at a new drug called inavolisib for breast cancer that has spread (WO41554)

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

Cancer type:

Breast cancer
Secondary cancers




Phase 3

This trial is looking at adding inavolisib to palbociclib and fulvestrant for breast cancer. 

It is open to people whose: 

  • cancer has stopped responding to treatment
  • cancer cells have a change (mutation Open a glossary item) in a gene called PIK3CA

More about this trial

You might have palbociclib to treat breast cancer that has spread to the surrounding tissue or elsewhere in the body. Breast cancer that has spread to another part of the body is secondary breast cancer

Palbociclib is used to treat breast cancer that is oestrogen receptor positive Open a glossary item and HER2 negative Open a glossary item.

You usually have this in combination with a hormone therapy drug such as fulvestrant

In some breast cancers, the PIK3CA gene has changed. This gene change affects a protein called P13K which is involved in cell growth.

Inavolisib (GDC-0077) is a new drug that blocks the activity of the PI3K protein. Research shows that blocking this protein can stop the growth of cancer. 

Researchers think that adding inavolisib to palbociclib and fulvestrant can improve treatment. But they aren’t sure, so want to find out more.

In this trial some people have palbociclib, fulvestrant and inavolisib. And some have a palbociclib, fulvestrant and a dummy drug (placebo Open a glossary item).

The main aims of the trial are to:

  • find out if adding inavolisib to palbociclib and fulvestrant slows cancer growth
  • learn more about the side effects

Who can enter

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

Who can take part

You may be able to join this trial if all of the following apply. You:

  • have adenocarcinoma Open a glossary item of the breast that has spread into surrounding tissues or elsewhere in the body. And you can’t have surgery or radiotherapy with the aim to cure.
  • have cancer that is oestrogen receptor positive Open a glossary item and, or progesterone receptor positive 
  • have cancer that is HER2 negative Open a glossary item
  • have breast cancer that has a change (mutation Open a glossary item) in the PIK3CA gene
  • have a sample of tissue (biopsy Open a glossary item) available or you are willing to give a new one
  • have cancer that got worse while having hormone therapy Open a glossary item or within 12 months of having an aromatase inhibitor Open a glossary item or tamoxifen Open a glossary item
  • have been through the menopause Open a glossary item if you are female or you are having a type of hormone therapy Open a glossary item called a luteinising hormone releasing hormone (LHRH). For example you are having goserelin or leuprolide or you may be asked to start this before you have trial treatment.
  • have cancer that the doctor can see and measure on a scan 
  • have satisfactory blood test results
  •  are willing to use reliable contraception during treatment and for a period afterwards if there is any chance you or your partner could become pregnant
  • are well enough to carry out all your normal activities, but might not be able to do heavy physical work (performance status of 0 or 1
  • are at least 18 years old

Who can’t take part

Cancer related
You cannot join this trial if any of these apply.

You have had previous treatment for breast cancer that included:

  • chemotherapy, radiotherapy or any other cancer treatment within 2 weeks of joining the trial
  • fulvestrant or a similar drug, unless you had this for a short time for early breast cancer 
  • treatment with certain types of targeted drugs called cancer growth blockers or drugs that work in a similar way. Your doctor will know this. 
  • treatment for breast cancer that reaches the whole body (systemic treatment Open a glossary item)

As well as the above, none of the following can apply. You:

  • have a rare type of breast cancer called metaplastic breast cancer
  • are suitable to have chemotherapy to treat your cancer 
  • have cancer that has spread to the brain or spinal cord unless it isn’t causing symptoms, has been treated and is stable. Or you have cancer that has spread to the tissues that surround the brain.
  • have had an experimental drug within 4 weeks of joining the trial 
  • have had any other cancer in the last 5 years. This is apart from CIS Open a glossary item of the cervix, non melanoma skin cancer Open a glossary item or early womb cancer.

Medical conditions
You cannot join this trial if any of these apply. You: 

  • can’t swallow tablets or have injections into a muscle
  • have a condition that means your digestive system Open a glossary item can’t absorb tablets
  • have type 2 diabetes Open a glossary item that needs treatment, or you have type 1 diabetes
  • have areas of fluid on the lung, in the heart or around the tummy that need regular draining 
  • have a problem with your eyes that would affect you taking part in the trial. You have an eye examination to check this.    
  • have oxygen at home everyday  
  • have an active lung condition that needs treatment including inflammation of the lung (pneumonitis Open a glossary item)
  • have had a heart attack, stroke or mini stroke in the last 6 months or a significant heart problem Open a glossary item. The trial team check if you have a heart condition before you join the trial.
  • have a problem with your liver Open a glossary item
  • have an inflammatory condition of the bowel such as Crohn’s disease or ulcerative colitis
  • take long term steroids unless it is a low dose
  • take medication that blocks an enzyme called CYP3A4 
  • have HIV, active hepatitis or a severe infection that needs treatment 
  • have had radiotherapy to a quarter of your bone marrow, a stem cell transplant Open a glossary itembone marrow transplant Open a glossary item or organ transplant Open a glossary item
  • have low levels of calcium and need to take bisphosphonates Open a glossary item or denosumab to prevent bone problems
  • have side effects from past treatments that aren’t getting better apart from hair loss, hot flashes or mild to moderate tingling in your hands or feet
  • have had major surgery, a recent traumatic injury or you plan to have surgery 
  • have any other medical condition or mental health problem that your doctor or the trial team think could affect you taking part

You cannot join this trial if any of these apply. You:

  • are allergic to any of the treatments in the trial or anything they contain
  • are pregnant or breastfeeding or intend to become pregnant 

Trial design

This phase 3 trial is taking place worldwide. The team need 400 people to take part including 30 from the UK. 

It is a randomised trial. There are 2 treatment groups. You are put into a group by a computer. 

You have 1 of the following:

  • palbociclib, fulvestrant and inavolisib
  • palbociclib, fulvestrant and a dummy drug 

Neither you nor your doctor can choose which group you are in. Nor will you know which group you are in. This is called a double blind trial. During the trial your doctor can find out which treatment you are having if necessary. 

Fulvestrant is an injection you have into a muscle. You have 2 injections each time. In the first month of treatment you have the injections twice. After that you have them once a month. 

Palbociclib is a tablet. You take them every day for 3 weeks. You then have a week of not taking it. Each 4 week period is called a cycle of treatment Open a glossary item.

Inavolisib or the dummy drug is a tablet you take every day.

You have treatment for up to 5 years, as long as it is working and the side effects aren’t too bad. 

Quality of life
The trial team ask you to fill out a questionnaire:

  • before you start treatment
  • at set times during treatment

The questionnaire asks about side effects and how you’ve been feeling. This is called a quality of life study.

Samples for research
You give some extra blood samples during treatment. You give them at specific times and the trial team will give you more information about this. 

They plan to use the samples to:

  • see how well the treatment is working 
  • look at genes Open a glossary item to understand more about breast cancer
  • look for substances called biomarkers Open a glossary item to help work out why treatment might work for some people and not for others

The team might also ask you to give 2 extra tissue samples. You don’t have to agree to this if you don’t want to. You can still take part in the trial. 

The trial team might ask to take photographs of your skin and mouth. The team plan to use these to understand more about how treatments affect the body. You don’t have to agree to this if you don’t want to. You can still take part in the trial. 

Hospital visits

You see the doctor and have tests before you can take part. These include:

You need to give a sample of tissue if there isn’t a suitable sample available. 

Each hospital visit takes between 1 and 5 hours. You may have some overnight stays. The trial team can let you know when these take place. 

You see the trial doctor for a check up:

  • once a week for a month and then 
  • once a month after that

You have a CT scan, MRI scan or PET-CT scan

  • every 8 weeks for 2 years and then
  • every 3 months until your cancer gets worse 

When you finish treatment you see the doctor 1 month later for a check up. 

Follow up
The team follow you up every 3 months when you finish treatment. You might see them at a routine hospital appointment, or they may call you to see how you are getting on. 

Side effects

The trial team monitor you during treatment and afterwards. Contact your advice line or tell your doctor or nurse if any side effects are bad or not getting better. 
Only a few people have had the combination of inavolisib, palbociclib and fulvestrant. The most common side effects we know about so far include:

Symptoms of high blood sugar include feeling thirsty, passing urine more often and blurry vision. This side effect can be severe in some cases. You may need to take a medication called metformin to control this. Your doctor explains what to watch for and closely monitors you during the first few weeks of trial treatment to make sure your blood sugar levels are well controlled.

Your doctor might recommend a home testing device to monitor your blood sugar levels. They will provide instructions for how and when to make these measurements. And when to contact the clinic with these results.

You should avoid having herbal supplements such as St John’s wort. And food or drink that affect an enzyme called CYP such as grapefruit or Seville oranges. These can affect how the body absorbs inavolisib.

The trial doctor will talk to you about all the possible side effects of treatment. You’ll have a chance to ask any questions you may have.

We have more information about the side effects of:

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 Nicholas Turner

Supported by


If you have questions about the trial please contact our cancer information nurses

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.

Last reviewed:

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