 A gene called PIK3CA has an important relationship with AKT. In tumours where this gene has been altered, or said to have mutated, the response to AZD5363 may be better. PIK3CA mutations are found commonly in breast cancers, and we will test for the presence of these mutations in both blood and tumour tissue samples that we ask you to provide. This study will also look at the relationship between tumours with PIK3CA mutations and the effect of the treatment. 