AUY922 With Lapatinib and Letrozole for ER+ HER2+ Advanced Breast Cancer

The dose and schedule of AUY922 is the MTD dose identified in the phase I, given as 1 hour infusion weekly. The Phase II component will have a 2 stage design single arm design. (Section 9.0). Overall response rate (ORR) is the primary endpoint. Estimated N=40 (12 in first stage) .A total of 39 response-evaluable participants is required. In the first stage, 12 response-evaluable participants will be accrued; if there are 3 or fewer CR+PRs, the study will stop for futility. There is a 55% probability of stopping early if, in fact, the ORR is 28%. If there are 4 or more CR+PRs, the study will proceed to the second stage and an additional 27 response-evaluable participants will be accrued. We will accrue 1 additional patient (then the needed 39 to account for attrition)