ERBB2 and breast cancer: The phase III BOLERO-1 trial evaluated the addition of the mTOR inhibitor everolimus to trastuzumab plus paclitaxel as a first-line treatment, and the phase III BOLERO-3 trial evaluated the addition of everolimus to trastuzumab plus vinorelbine for trastuzumab-resistant patients with HER2+ BC [66,72].