Aggressive breast cancer protein discovered

Researchers have identified a protein which may help trigger the spread of some types of aggressive breast cancer, opening up the possibility of new treatments.

The study, by researchers from Barts Cancer Institute, Queen Mary, University of London, was funded by the Breast Cancer Campaign and the Medical Research Council. Researchers examined samples of breast cancer tissue from two cohorts of women with breast cancer and studied the expression of a protein called integrin αvβ6, which has been shown to interact with HER2 to stimulate cancer growth.

The researchers found that women who had a higher expression of integrin αvβ6 in their breast cancer tissue had poorer five-year survival rates, particularly when they were also HER2 positive.

Up to a third of breast cancers are HER2-positive cancers. These are particularly aggressive cases of breast cancer where growth is driven by a protein called human epidermal growth factor receptor 2 (HER2). 

Seventy percent of people with HER2-positive breast cancers develop resistance to Herceptin, the main drug treatment for these cancers, leaving them with no treatment options. Herceptin works by binding to the protein receptors and blocking them so HER2 cannot stimulate the growth of the breast cancer cells.

The researchers then studied mice that had been grafted with breast cancer tissue. A potential new treatment called 264RAD was found to block integrin αvβ6 in the mice.

This treatment, given in combination with Herceptin, stopped cancer growth, even in breast cancer tissues resistant to Herceptin.

The discovery that integrin αvβ6 may play a role in mediating the growth and progression of these cancers could open up new treatment possibilities for people with HER2-positive cancers.

Clinical trials of 264RAD in women with this particularly high-risk type of breast cancer are now required.