Randomised phase II window study of short-term preoperative treatment with the PI3K inhibitor GDC-0941 plus Anastrozole versus Anastrozole alone in patients with ER-positive primary breast cancer

In women with ER-positive breast cancer about to undergo surgery, does two week's pretreatment with a new drug (the PI3K inhibitor GDC-0941, given in combination with the estrogen-blocker anastrozole) increase the benefits of anastrozole in slowing down tumour cell growth, as measured by laboratory measurements on tumour cells?