A trial looking at GDC0941 and anastrozole for oestrogen positive breast cancer (OPPORTUNE)

This trial is looking at a drug called GDC0941 and a hormone therapy called anastrozole for breast cancer that is positive for oestrogen hormone receptors (ER positive). This trial is open to women whose periods have stopped permanently (they are post menopausal).

Doctors usually treat ER positive breast cancer in post menopausal women with surgery, followed by a hormone treatment called anastrozole. Sometimes they give anastrozole before surgery to shrink the cancer.

GDC0941 is a type of biological therapy. It is a cancer growth blocker. It stops signals that cancer cells use to divide and grow. We know from laboratory studies that it may help to stop cancer cells from dividing and growing.

The researchers think the combination of GDC0941 and anastrozole may work well for women with ER positive breast cancer. In this trial, before your surgery you have either anastrozole only or GDC0941 and anastrozole.

The aims of this trial are to find out

• How well the combination of GDC0941 and anastrozole works for women with ER positive breast cancer

• How safe this combination is

• What the side effects are