HER2 Imaging Study to Identify HER2 Positive Metastatic Breast Cancer Patient Unlikely to Benefit From T-DM1

The main objective of the trial is to prospectively evaluate the ability of a zirconium 89 labelled trastuzumab PET, to predict, before initiation of the treatment, treatment failure to a new targeted drug: T-DM1. At the same time, the early FDG-PET/CT, performed after 1 course of T-DM1, will also evaluated for its ability to predict non response to TDM1.