A trial of exemestane with or without everolimus for breast cancer that is oestrogen receptor positive and has spread outside the breast (BOLERO 2)

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.