“I was keen to go on a clinical trial. I wanted to try new cancer treatments and hopefully help future generations.”
A trial of exemestane with or without everolimus for breast cancer that is oestrogen receptor positive and has spread outside the breast (BOLERO 2)
We know that this is an especially worrying time for people with cancer and their family and friends. We have separate information about coronavirus and cancer. Please read that information alongside this page. We will update that information as guidance changes.
This trial was looking at exemestane and everolimus (Afinitor) for breast cancer that is sensitive to the female hormone oestrogen (oestrogen receptor positive breast cancer). It recruited people with breast cancer that was locally advanced, or had spread to another part of the body (metastatic or secondary breast cancer).
Doctors often use hormone therapy to treat hormone receptor positive breast cancer. Letrozole and anastrozole are 2 hormone therapy drugs they commonly use. But if cancer comes back or continues to grow after having these drugs, doctors are not sure of the best treatment to use. In this trial, everybody had a hormone therapy drug called exemestane. Some people also had a drug called everolimus.
Everolimus (also known as RAD001) is a type of biological therapy. It is a cancer growth blocker. It works by targeting a protein called mTOR and stops some of the signals it sends that make cancer cells divide and grow.
The aim of this trial was to see if everolimus and exemestane together worked better than exemestane alone for hormone receptor positive breast cancer that had come back or continued to grow after treatment with letrozole or anastrozole.
Summary of results
The trial team found that on average, women who took exemestane and everolimus had a longer period of time without any sign of their cancer getting worse than women who had exemestane alone.
The trial recruited 724
The trial was randomised so neither the women taking part nor their doctors could decide which treatment they had. And they didn’t know which treatment they were having either. This is called a
- 485 women had exemestane and everolimus
- 239 had exemestane and a dummy drug (
The trial team followed up the women for an average of 18 months. They found that the average length of time women had without any sign of their cancer getting worse was
- Just under 8 months for women who had exemestane and everolimus
- Just over 3 months for women who had exemestane and placebo
Doctors call this an improvement in progression free survival. The researchers don’t yet know if adding everolimus to exemestane will help women to live longer overall.
We have based this summary on information from the team who ran the trial. The information they sent us has been reviewed by independent specialists (
How to join a clinical trial
Professor Robert Coleman
National Institute for Health Research Cancer Research Network (NCRN)