Several reports have shown that pharmacological inhibition of HSP90 activity restores trastuzumab sensitivity in preclinical models of HER2+ breast cancer (reviewed in [27]); however, clinical trials with HSP90 inhibitors have met with little success so far [28] due to several reasons, including off-target effects and poor solubility [16,28]. This evidence concerns the gene HSP90AA1 and breast carcinoma.