A trial looking at everolimus on its own or with exemestane and comparing it with capecitabine for advanced breast cancer (BOLERO 6)

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

Cancer type:

Breast cancer




Phase 2

This trial is comparing the chemotherapy drug capecitabine with a drug called everolimus on its own and everolimus alongside the hormone therapy drug exemestane.

It is for women who have been through the menopause and who have breast cancer that

  • Has grown into tissue surrounding the breast or spread to another part of the body
  • Has receptors for the hormone oestrogen (hormone receptor positive)
  • Does not have receptors for a protein called HER2 (HER2 negative)
  • Has come back or got worse despite having the hormone therapy drugs letrozole or anastrozole

Doctors may treat locally advanced or secondary breast cancer with hormone therapy.  Letrozole and anastrozole are 2 drugs they can use.

But sometimes breast cancer comes back or gets worse despite having this type of treatment. If this happens, you may have another hormone therapy drug called exemestane or a chemotherapy drug called capecitabine. You may also have a drug called everolimus with exemestane.

Everolimus (also called Afinitor) stops a protein called mTOR from working properly. Cells usually divide and grow in an orderly way. But in cancer cells, proteins such as mTOR can behave abnormally and the cells grow out of control. If mTOR is blocked, this may stop or slow the growth of the cancer.

The aim of the trial is to compare the following 3 treatments to see which is better for post menopausal women with hormone receptor positive breast cancer that has come back or got worse despite having letrozole or anastrozole.

  • Everolimus on its own
  • Everolimus and exemestane
  • Capecitabine

Who can enter

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

  • You have breast cancer that has grown into tissue surrounding the breast or spread to another part of your body
  • Your cancer has receptors for the hormone oestrogen (hormone receptor positive) and has got worse despite having the hormone therapy drugs letrozole or anastrozole
  • You can’t have surgery or radiotherapy to try to cure your cancer
  • You have been through the menopause
  • You have recovered from side effects of other cancer treatment unless they are very mild (apart from hair loss)
  • You have at least one area of cancer that can be measured on a scan and is at least 5mm across
  • You have satisfactory blood test results
  • You are well enough to be up and about for at least half the day (performance status 0, 1 or 2)
  • You are at least 18 years old

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

  • Have cancer that has spread to your brain or spinal cord (your central nervous system)
  • Have cancer with a lot of receptors for a protein called HER2 (HER2 positive cancer)
  • Have areas of cancer blocking the lymph vessels in both lungs (lymphangitic carcinomatosis)
  • Have had more than 1 type of chemotherapy for breast cancer that has spread
  • Have had capecitabine or a similar drug in the last 6 months (your doctor can tell you this)
  • Have already had exemestane, everolimus, or a similar drug (your doctor can tell you this)
  • Have had radiotherapy in the last 4 weeks (or in the last 2 weeks if it was just to treat pain caused by cancer spread to the bone)
  • Have had any other cancer in the last 5 years apart from carcinoma in situ of the cervix, non melanoma skin cancer or very early stage melanoma that was successfully treated
  • Are known to be very sensitive to drugs that block mTOR or similar proteins, or to 5FU or capecitabine (or anything it contains)
  • Have low levels of a body substance called DPD or any other similar inherited condition (your doctor can advise you about this)
  • Are currently having hormone replacement therapy (HRT) unless you stop it before starting the trial treatment
  • Are taking steroids or other drugs that damp down your immune system (steroid eye drops, inhalers or injections into just one part of your body are allowed)
  • Take drugs to thin your blood, such as warfarin
  • Take other medication that can affect body substances called cytochrome P enzymes for 7 days or more at any time during the 2 weeks before starting the trial treatment
  • Have taken an anti viral drug called sorivudine (or a related drug) in the last 4 weeks
  • Have problems with blood clotting
  • Are known to be HIV positive
  • Have any other medical condition that could affect your taking part (the trial doctors can advise you about this)

Trial design

This is a phase 2 trial. The trial team need 300 women to take part in different countries around the world. It is a randomised trial. The women taking part are put into treatment groups by a computer. Neither you nor your doctor will be able to decide which group you are in.  You will have one of the following treatments

BOLERO 6 trial diagram

As long as you don’t have bad side effects, you can carry on having the trial treatment for as long as it helps you.

The trial team will ask you to fill out 2 questionnaires before you start treatment, every 6 weeks during treatment and when you finish treatment. The questionnaires will ask about side effects and how you’ve been feeling.  This is called a quality of life study.

After 3, 6 and 12 weeks of treatment, they will also ask you fill out a questionnaire asking how satisfied you are with the trial treatment.

Hospital visits

You see the trial team and have some tests before you start treatment. The tests include

  • Physical examination
  • Heart trace (ECG)
  • Heart scan (echocardiogram or MUGA scan)
  • Blood tests
  • CT scan or MRI scan
  • Bone scan or X-rays of your bones (if you haven't had this done recently)

If an area of cancer is visible on your skin, your doctor may take a photograph of this area. It will not be possible to identify you from the photograph.

You may also have tests to see how well your lungs are working (lung function tests).

You see the trial team once every 3 weeks for the first 6 weeks and then once every 6 weeks for the rest of the time you have the trial treatment. You have a physical examination and blood tests each time. The hospital visits last for 2 to 3 hours.

You have a CT or MRI scan every 6 weeks during treatment. You may need to have more bone scans and X-rays. And if your cancer is visible on your skin, the trial team may take more photographs when you have your scans.

When you finish treatment, you see the trial team again within 2 weeks. You have more blood tests, a CT or MRI scan and a bone scan.

The trial team will check how you are a month after you stop treatment. They may ask you to go to hospital for this. Or they may contact you by phone.  A member of the trial team will then phone you every 3 months to see how you are and whether you've started any other treatment.

Side effects

The most common side effects of everolimus include

The side effects of capecitabine include

  • A drop in blood cells causing an increased risk of infection, bleeding problems, tiredness and breathlessness
  • Tummy (abdominal) pain
  • Diarrhoea or constipation
  • Indigestion
  • Feeling or being sick
  • Sore mouth
  • Changes to your skin and nails including redness and peeling on the palms of your hands or soles of your feet (hand-foot syndrome)
  • High amounts of bilirubin in your blood
  • Loss of appetite
  • Tiredness (fatigue)
  • High temperature
  • Dizziness and headaches
  • Eye problems

The most common side effects of exemestane include

  • Joint pain
  • Dizziness
  • Tiredness
  • Tummy ache, sickness or indigestion
  • Hot flushes
  • Muscle pain
  • Sweating

We have more information about

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

Dr Stephen Chan

Supported by


Questions about cancer? Contact our information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:

Oracle 12152

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

Harriet wanted to try new treatments

A picture of Harriet

“I was keen to go on a clinical trial. I wanted to try new cancer treatments and hopefully help future generations.”

Last reviewed:

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